University Of California At Davis

NIH Research Projects · FY 2026 · 2024-08

PROJECT SUMMARY / ABSTRACT Roughly 90,000 adolescents and young adults (AYAs: 15–39) are diagnosed with cancer in the United States each year. Disparities in cancer mortality exist among AYAs with Ewing sarcoma (EWS) and osteosarcoma (OS), which may be partially due to unequal access to evidenced-based, standardized care (guideline concordant care; GCC). Many AYAs with cancer do not receive GCC, especially those with who are older and with limited resources. My prior research demonstrated 50% of AYAs with OS in California received guideline concordant care and the absence of such care negatively impacted survival. Increasing delivery of guideline concordant care in this patient population could markedly improve survival, especially in traditionally underserved patients (e.g., those with public insurance, other than White race/ethnicity). The barriers to the delivery of guideline concordant care are not clearly identified in AYAs. To fill this critical gap and gain essential training, I will employ an implementation mapping process to develop strategies that increase adoption of evidence-based practices, identify barriers and facilitators to the delivery of guideline concordant care, and develop an implementation blueprint to pilot an intervention to improve delivery of GCC in AYAs with EWS and OS. The specific aims are: 1) Identify barriers and facilitators to delivery of GCC for AYA patients with EWS and OS, 2) Systematically develop a tailored implementation blueprint for delivery of GCC care for AYA patients with EWS and OS, and 3) Evaluate the feasibility and acceptability of a cancer care delivery implementation blueprint to improve delivery of GCC in a pilot trial. The long-term goal of my research program is to improve cancer health equity for AYA patients with cancer. The proposed research and training plan supports my need to: (1) Expand skills in qualitative methods (i.e., thematic analysis); (2) Develop skills in implementation science methods; (3) Gain experience conducting a cancer care delivery pilot trial; and (4) Obtain preliminary data for an R01 proposal for a refined and expanded R01 cancer care delivery trial. This proposal is supported by an outstanding mentorship team and scientific/ content advisory committee, with substantial expertise in cancer care delivery research, qualitative research, implementation science, AYA oncology, and treatment of sarcomas. Formal training will be sought in qualitative methods and implementation science methods, while concurrently building essential skills in leadership. Collectively, this research proposal and career development plan will firmly secure my position as an independent physician-scientist and national leader as an AYA cancer care delivery researcher.

NIH Research Projects · FY 2025 · 2024-08

PROJECT SUMMARY Liver cancer is a major cause of cancer-related deaths within the United States, being the fifth and seventh leading cause of cancer deaths among men and women, respectively. There is a high demand for new and more effective therapeutics for the treatment of liver cancer, especially for the most common hepatocellular carcinoma (HCC), with an improved understanding of vital regulatory factors underlying HCC cell metabolism essential for tumor progression. Genome-derived noncoding microRNAs (miRNAs or miRs) have been revealed as critical elements to control posttranscriptional gene regulation, and restoration of liver-enriched, oncolytic miRNAs (e.g., let-7-5p isoforms, miR-122-5p, and miR-148a-3p) lost or downregulated in HCC cells represents a new therapeutic strategy. However, current miRNA functional and experimental therapeutic studies are limited to the use of miRNA mimics chemo-engineered in vitro and comprised of extensive and various types of artificial modifications, which are totally different from natural miRNA molecules produced in vivo. This is also in sharp contrast to protein research and therapy in which bioengineered or recombinant protein agents produced and folded in vivo, rather than synthetic polypeptides or proteins made in vitro, have been used and found enormous success. To overcome this barrier, the PI has recently developed a novel RNA molecular bioengineering platform technology, based upon specific hybrid tRNA/pre-miRNA molecules identified in the PI’s lab as carriers, to achieve high-yield and large-scale, in vivo fermentation production of true biologic or bioengineered RNA (BioRNA) molecules for basic and translational research. Our following studies have demonstrated that miRNA (e.g., let-7c-5p) is selectively released from BioRNA “prodrug” in human HCC cells to regulate target gene expression (LIN28B) and control cellular processes (tumorsphere formation), and liposome-polyethylenimine (LPP) nanocomplex is superior to in vivo-jetPEI to deliver BioRNA into orthotopic HCC tissues and inhibit tumor growth in mouse models. Our further efforts have led to the identification of proper human tRNAs to couple with human hsa-pre-miRNAs as new carriers to offer humanized BioRNAs to target HCC. In addition, humanized BioRNA/miR-148a-3p is precisely processed to miR-148a-3p in human HCC cells to modulate specific amino acid and glucose transporter expression towards the control of aminolyses and glycolysis. Given these exciting preliminary findings, we hypothesize that novel, HCC-targeted, humanized BioRNAs can be bioengineered and used to dissect HCC nutrient homeostasis and tumor metabolism. To test the hypothesis, we proposed to (i) design, clone, express, and purify a focused group of novel humanized BioRNAs for the inhibition of HCC cell viability (Aim 1), (ii) delineate the mechanistic actions of BioRNAs in the control of HCC cell metabolism (Aim 2), and (iii) establish the effectiveness and safety of candidate BioRNAs in the modulation of HCC tumor metabolism and progression in vivo (Aim 3). Successful completion of this project will offer a set of one-of-a-kind, biologic, HCC-targeted RNA molecules as research tools, establish new roles for miRNAs in the control of HCC cell metabolism, and build a solid foundation for the development of new remedies to improve the treatment of lethal HCC.

NIH Research Projects · FY 2024 · 2024-08

Project Summary/Abstract Autism Spectrum Disorder (ASD) and Attention-Deficit/Hyperactivity Disorder (ADHD) are significant public health concerns in the United States, with substantial economic and societal implications. While these disorders have a notable hereditary component, there is growing recognition of the role environmental factors play in their development. Exposure to endocrine disrupting chemicals (EDCs) during pregnancy, a critical period for neurodevelopment, may have adverse effects on fetal brain development. An expanding body of evidence supports associations between prenatal EDC exposure and behavioral problems related to ASD and ADHD. However, there remains a substantial knowledge gap regarding the molecular mechanisms through which prenatal EDC exposure influences neurodevelopment. Inflammation/immune dysregulation and epigenetic modifications have emerged as potential mediators in this complex pathway. Prenatal EDC exposure could lead to dysregulated inflammatory responses or DNA methylation changes, which are further related to neurodevelopmental disorders such as ASD and ADHD. However, few epidemiological studies have comprehensively addressed these chemical exposures, potential mediators, and neurodevelopmental outcomes in a single investigation. Leveraging the rich dataset available through the Environmental influences on Child Health Outcomes (ECHO) program, the proposed research seeks to evaluate the mediating role of cytokines and DNA methylation in this association, addressing crucial gaps in our understanding of the etiology of ASD and ADHD. To achieve this overarching goal, three specific aims will be pursued: (1) examine whether prenatal EDC levels, as an individual compound or in a mixture, are associated with behavioral problems assess using the Social Responsiveness Scale (SRS) and Child Behavior Checklist (CBCL) during early childhood (n~3000); (2) perform mediation analysis to evaluate cytokines in prenatal maternal blood and cord blood as potential mediators (n~400); and (3) perform mediation analysis using the “Meet-in-the-Middle” approach to evaluate cord blood DNA methylation as a potential mediator (n~400). Throughout the duration of this award, I will engage in multidisciplinary mentored training in immunology, epigenetics, molecular epidemiology, and statistical methodologies of analyzing complex chemical mixtures, cytokine and DNA methylation data, and mediation analysis integrated with mixture approaches. I will interact with trainees and faculty at both UC Davis and the broader ECHO program, having the opportunity to discuss and present my work and to engage with and lead collaborative teams. These training and research activities will prepare me to transition into an independent researcher in environmental epidemiology with a specific focus on molecular mechanisms. Ultimately, this will contribute to advancing our understanding of how prenatal EDC exposure operates through molecular mechanisms to influence child neurodevelopment.

NIH Research Projects · FY 2025 · 2024-08

PROPOSAL SUMMARY Exposure to viral or bacterial infections during pregnancy increases risk for offspring neurodevelopmental disorders, including autism and schizophrenia. Gestational biomarkers indicate that the maternal immune response plays a critical role in altered fetal neurodevelopment. Our ability to mitigate the harmful effects of maternal immune activation (MIA) on offspring neurodevelopment is limited by our incomplete mechanistic understanding of the neurobiological changes associated with prenatal exposure to MIA. While rodent studies have shown similarities between alterations in brain and behavioral development in MIA-exposed offspring and changes observed in human neurodevelopmental disorders, there are limitations in translating these findings to human neuroanatomy and physiology. It is therefore necessary to expand this research to a preclinical model more closely related to humans, such as nonhuman primates (NHPs). My primary mentor’s laboratory (Bauman) has developed the first viral-mimic based rhesus macaque model of MIA exposure in pregnancy. For this K01 Career Development Award, I propose to leverage the entirety of biobehavioral data available for the NHP MIA model to examine the effects of neuroimmune changes on behavioral and brain alterations in MIA-exposed NHPs. My outstanding mentorship team will provide foundational training in immunology (Van de Water) and the use of NHP models (Bauman) to accelerate complex translational biomedical research in neurodevelopmental disorders (Schumann). This award, which represents a critical next step in my development as an independent research scientist, provides an opportunity to make use of my unique skill set in human and NHP cellular and molecular neuroanatomy, while expanding the breadth of my research foci in the unique institutional environment provided by UC Davis and the California National Primate Research Center. Our research will contribute to our understanding of the behavioral and neurobiological changes associated with prenatal exposure to MIA. Specifically, we will apply novel behavioral phenotyping paradigms to evaluate alterations in socioemotional behavior in the MIA-exposed NHP (Aim 1a). We will longitudinally map the development of the amygdala in MIA-exposed NHPs and controls to understand the course of MIA- induced structural brain changes (Aim 1b). Using postmortem tissue collected from subjects at two critical age time points, we will examine neuroimmune proteomic alterations in the amygdala and medial prefrontal cortex (Aim 2a). Using markers for neuroimmune targets identified in Aim 2a, we will map the expression of neuroimmune transcripts in specific cell types in brain tissue sections (Aim 2b). Together, these data build a comprehensive picture of MIA-induced changes in NHP brain circuitry, toward the ultimate goal of identifying pathways of vulnerability and critical periods for novel, targeted interventions and biotherapeutics.

NIH Research Projects · FY 2024 · 2024-08

Project Summary: Zoonotic viral infections are responsible for the majority of emerging and re-emerging infectious diseases in humans. The current strategies for controlling vector-borne virus transmission are insufficient and additional strategies are urgently needed. Our long-term goal is to define and test recombinant antiviral sensor/effector strategies that broadly inhibit known and emerging viruses to control or prevent vector- borne and zoonotic viral diseases. The overall objective of this application is to develop Recombinant Enhanced Antiviral Sensors (REAVRs), which combine virus-sensing domains with effector domains from different antiviral proteins to create proteins with unique and broadly-acting antiviral activities. Our central hypothesis is that combining diverse virus-sensing domains with effector domains from other antiviral proteins will make them more effective and result in increased resistance against diverse viruses. The rationale of this proposed project is that once this strategy of synthesizing modular, broadly antiviral recombinant proteins is established, they can be applied to whole organisms that are important vectors for viral diseases. Based on strong preliminary data, the central hypothesis will be tested by pursuing three specific aims: 1) generate and optimize REAVRs and evaluate their antiviral effects in cultured cells; 2) identify and characterize dsRNA- and virus-induced promoters in mosquito cells and in vivo; and 3) generate REAVR-expressing mosquitoes and test their antiviral effects against arbovirus infections. Under the first aim, we will generate second generation REAVR proteins and test their antiviral activity against a broad panel of viruses in established reporter, RNA integrity, and congenic cell culture- based assays. In the second aim, we will use long-read and short-read RNA-seq strategies to generate a validated, high-resolution analysis of Ae. aegypti transcriptional changes in response to poly(I:C) and virus challenge and define promoters driving these responses. Under the third aim, we will use the CRISPR/Cas9 gene editing system to site-specifically insert the second generation REAVRs into transgenic mosquitoes under control of various inducible promoters, including dsRNA-inducible promoters, and determine their effect on mosquito sensitivity to a panel of arboviruses and virus transmission. The proposed research is significant because the proposed strategy of enhancing the host immune response has great potential for the better control of the transmission of zoonotic viruses and unlike current strategies will inhibit multiple different virus families. This project is innovative because it introduces a novel approach to prevent virus transmission by combining different antiviral sensing and effector domains, which is predicted to yield proteins with antiviral activities against many types of viruses. Moreover, the identification of dsRNA-induced promoters will expand our foundational understanding of arthropod immunology, and increase the repertoire of available mosquito promoters that could be employed in the generation of transgenic mosquitoes. Taken together, this project is introducing an innovative strategy for better control of zoonotic viruses that is expected to have a positive impact on the field.

NIH Research Projects · FY 2025 · 2024-08

Project Summary/Abstract Many studies utilize resting-state functional magnetic resonance imaging (rsfMRI) metrics, such as functional connectivity (FC), to study the neural underpinnings of autism and identify functional brain networks related to autistic behaviors. However, these findings remain inconsistent, with reports of underconnectivity and overconnectivity in multiple resting-state networks. FC measures the temporal correlation between the blood oxygen level dependent (BOLD) signal of distinct brain regions. In fMRI, the BOLD signal indirectly measures neuronal activity by detecting changes in oxygenated blood flow, which occurs through local blood vessel dilation. In addition to neuronal activity, changes in brain vascular function can affect local oxygenated blood flow, and thus the BOLD signal within a region and FC between regions. Characterizing these cerebrovascular effects on FC is critical to understanding neuronal and vascular sources of connectivity in populations with potential cerebrovascular heterogeneity, such autism or early development. In this study, we utilize a novel, non- invasive method to characterize cerebrovascular reactivity (CVR), the vasodilatory capacity of cerebral blood vessels, in autistic and non-autistic children, based solely on rsfMRI BOLD signals (Aim 1). We then use this novel information to investigate the mechanism linking vascular function to FC, using the amplitude of low frequency fluctuations (ALFF), a resting-state measure of local BOLD amplitude that has been associated with both neuronal and vascular physiology (Aim 2). Using data from the Autism Phenome Project (APP), a longitudinal neuroimaging program that specializes in early age scanning (2-12 years old) in autistic and non- autistic children, we will compare age-trajectories of CVR and its effect on FC in autistic and non-autistic children starting from 2 years old. In acquiring and analyzing data from young autistic and non-autistic participants, I will receive unique clinical and neuroimaging training, specifically in autism, to support my career as an independent investigator, developing novel neuroimaging biomarkers to characterize cerebral physiology in autism. Ultimately, providing insight into cerebrovascular differences and enhancing FC interpretations in autism, starting from early age, will help disentangle its heterogeneity to inform meaningful, early interventions.

NIH Research Projects · FY 2024 · 2024-07

PROJECT SUMMARY/ABSTRACT The goal of this proposal is to install an integrated radiosynthesis system for the production of non-commercially available PET radiotracers for preclinical imaging applications at the UC Davis Center for Molecular and Genomic Imaging (CMGI). We propose to incorporate a commercial radiosynthesis unit dedicated to the production of PET radiotracers complete with shielding enclosures allowing the safe and efficient production of the radiotracers. The integrated system will allow for the automated production of PET radiotracers radiolabeled with the positron emitter fluorine-18. It includes all necessary components to support radiotracer production and will allow us to synthesize both established and novel PET radiotracers. As the NIH roadmap calls for an emphasis on translational research and has identified molecular imaging as a priority, UC Davis is proposing to strengthen functional and molecular imaging in animal models for future translation to humans by utilizing the system. The system will be installed at the CMGI, which is a campus-designated and supported core facility providing infrastructure and expertise to conduct in vivo imaging studies in animal models, from rodents to non-human primates and companion animals. CMGI is the only location on our campus that oversees a cyclotron and radiochemistry facilities dedicated to preclinical imaging research. Institutional support provided to the CMGI ensures the successful operation and maintenance of the system for its lifetime. The system will support at least 10 major and minor users who are conducting NIH-funded research in diverse areas such as gene therapy, neurology, oncology, toxicology, metabolic disorders, nanotechnology and biomedical engineering.

NIH Research Projects · FY 2025 · 2024-07

PROJECT SUMMARY Dysregulation of pancreatic islet function is a hallmark of type 2 diabetes mellitus (T2DM) progression. Thus, understanding the exact mechanisms by which islet function can be preserved and regulated is crucial. It is increasingly evident that α-cells play an important role in the potentiation of glucose-stimulated insulin secretion (GSIS), thereby expanding their function beyond that of the traditional counterregulatory role. However, the regulation of intra-islet communication and its role in maintaining normal islet function remains incompletely defined. Endogenous potentiators of β-cell function include glucagon and glucagon-like peptide-1 (GLP-1). While GLP-1 and glucagon both potentiate GSIS by binding to the GLP-1 receptor (GLP-1R) on the β-cell, GLP-1 is 300-fold more potent at promoting GSIS than glucagon. Canonically, glucagon is produced by the α-cell, and GLP-1 is produced by the enteroendocrine L-cells in the gut. However, a growing body of literature reports that under pathophysiological conditions, α-cells can produce and secrete active GLP-1. Our lab has identified the signaling protein 14-3-3-ζ as a key regulator of α-cell endocrine profile. Specifically, we have found that β-cell 14-3-3-ζ ablation and inhibition increases GSIS and activates α-cell active GLP-1 production and secretion in mouse and human islets in vitro. How β-cell 14-3-3-ζ expression is regulated and the role of the α-cell in the impact of β-cell 14-3-3-ζ on islet function is unknown. Therefore, the driving hypothesis of this project is that β-cell 14-3-3-ζ is a crucial regulator of α-cell to β-cell crosstalk. I will pursue our hypothesis in the following aims: Aim 1 will define a new pathway regulating β-cell14-3-3-ζ expression. Specifically, our lab has found that enhanced β-cell GLP-1R signaling decreases 14-3-3-ζ expression in the β-cell. I will study β-cells and mouse and human islets to define the key signaling nodes by which β-cell GLP-1R signaling decreases 14-3-3-ζ expression. Aim 2 will determine the efficacy of targeting 14-3-3-ζ in the β-cell to improve islet function in high fat diet-fed mice. Aim 3 will determine the effect of β-cell 14-3-3-ζ ablation on bidirectional islet cell crosstalk. Through these carefully designed experiments, I aim to shed light on a new crosstalk mechanism between α- cells and β-cells, potentially opening new avenues for understanding and treating T2DM. The training plan will be facilitated by the mentorship of my sponsor, mentorship team and the exceptional facilities and graduate student support at UC Davis. This proposal describes an integrative and comprehensive training plan to support my scientific and professional development and propel me toward my long-term goal of becoming an independent researcher focused on the molecular underpinnings of metabolic disease.

NIH Research Projects · FY 2026 · 2024-07

The Tantillo group applies modern computational chemistry to elucidate and manipulate the mechanisms by which terpenes (natural products derived from isoprene oligomers) and terpenoids (functionalized terpenes) are produced in nature. Techniques employed range from quantum chemistry to automated docking augmented by chemically meaningful constraints. The terpene/terpenoid class of natural products is the largest and most diverse in terms of both structures and biological activities relevant to humans (e.g., anti-cancer, anti-inflammatory, analgesic, anti-convulsive, anti-depressant, neuroprotective, anti-allergic, antibiotic, and others). The overall vision for the research program is to rationally expand the chemical space of terpenes and terpenoids using mechanistic insights obtained from computaional chemistry experiments, thereby providing new input for the testing and development of terpene-like compounds with potential new biological activities. A bottom-up modeling approach will be employed in which specific contributions to catalysis and selectivity are assessed using a series of theoretical experiments designed to reduce complicating factors (i.e., we will characterize inherent reactivity in the absence of an enzyme using quantum chemistry, then model specific enzyme-substrate interactions, then model the effect of active site shape using methods developed in-house that are specific for terpene synthases). Our predictions will be put to the test via synthesis of methyl- edited substrates and characterization of their reactions with terpene synthases we design. In addition to providing access to new terpene synthase enzymes that produce terpene-like molecules with new carbon skeletons and methylation patterns that can be tested for biological activity, this multi-step, multi-scale modeling approach will hopefully transform how computational studies on cyclization/rearrangement-promoting enzymes are generally carried out, in that it avoids the many issues associated with assessing contributions associated with specific effects from simulations that involve entire enzyme-substrate systems alone.

NIH Research Projects · FY 2025 · 2024-07

PROJECT SUMMARY The small freshwater cnidarian Hydra has played a crucial role in several scientific breakthroughs, most notably being the first animal where regeneration was discovered in 1744. Over the years, different Hydra species contributed to fundamental findings, but Hydra vulgaris has become the standard "Hydra model" in modern molecular research. With a chromosome-level genome assembly and tools to test gene function, H. vulgaris is a prime model for developmental and regenerative biology but is also an emerging model in various fields including neuroscience and microbiome research. In contrast, Hydra oligactis, another Hydra species, remains underutilized despite its biologically relevant distinct features. Unlike H. vulgaris, H. oligactis exhibits deficiencies in regenerating its aboral end and undergoes senescence and death upon gamete production. The sharp contrasts between these closely related species offer a unique comparative platform for exploring molecular mechanisms in regeneration and aging. Despite being behind in tools and resources, H. oligactis can be reliably cultured, making it a promising candidate for functional studies. Completion of the proposed aims will bridge the gap between the two species: 1. Build Genomic and Transcriptomic Resources: Develop a chromosome-scale genome assembly with gene regulatory annotations, and a single-cell expression atlas for H. oligactis, paralleling the resources available for H. vulgaris. 2. Implement Transgenesis and siRNA Knockdown: Establish transgenesis in H. oligactis and create transgenic lines that express fluorescent proteins in specific lineages. These lines will enable the optimization of gene knockdown through siRNA electroporation. 3. Develop CRISPR Gene Editing: Utilize the inducible egg production in H. oligactis to troubleshoot CRISPR-Cas9 mediated gene editing. The immediate goal is to tag the endogenous EF1-alpha gene, a strategy that will inform future gene editing attempts in both H. oligactis and H. vulgaris. The completion of these aims will equip H. oligactis with tools and resources comparable to H. vulgaris, enabling functional studies and comparative analyses. This comparative approach holds potential implications for various scientific fields, including developmental and regenerative biology, aging, neuroscience, microbiome research, and biophysics. This project is therefore highly responsive to the FOA (PAR-21-167), which calls for the development and improvement of animal models that are relevant to multiple NIH Institutes.

NIH Research Projects · FY 2025 · 2024-07

Project Summary/Abstract The broad objective of this proposal is to understand the molecular mechanism of homologous recombination (HR) in humans, and to understand how the consequences of defects in recombinational DNA repair result in chromosomal instability that underlie the predisposition to cancers. The proteins involved in a central step of HR, DNA pairing, include RAD51, BRCA2, and the RAD51 paralogs, RAD51B, RAD51C, RAD51D, XRCC2, and XRCC3. Mutations in these proteins are known to predispose individuals to cancer. The objective is to understand the functions of these proteins in genome maintenance via recombinational DNA repair, and how these proteins mediate and potentiate homologous DNA pairing by RAD51. We propose to understand their mechanisms of action through biochemical analyses of reconstituted reactions using purified proteins; characterization of defective mutant proteins identified in the patient population, and by visualizing the individual behavior of these proteins acting on single molecules of DNA. The Specific Aims are to understand the molecular functions of BRCA2 protein and to determine the functions of the RAD51 paralogs in RAD51 filament formation and RAD51-dependent DNA pairing.

NIH Research Projects · FY 2025 · 2024-07

PROJECT SUMMARY/ABSTRACT Language delays are common in autism and ADHD. Prior studies on early language development in infants developing autism or ADHD have examined each condition separately and are largely incompatible with a transdiagnostic framework, limiting our understanding of whether similar or different mechanisms contribute to language delays in these populations. One proposed mechanism of early language learning is absent reference, which is conceptualized as a three-way connection between words, imperceptible physical entities, and mental representations. To better understand the developmental course of absent reference in typically and atypically developing samples, longitudinal studies beginning early in life are needed. Additionally, while social contingency in the infant-toddler period appears to be important for the development of language, it is unknown whether absent reference mediates this association. This F31 proposal will leverage the primary mentor’s longitudinal sample of n=163 infants at elevated and typical familial likelihood for autism and ADHD, with data collected at 6/9, 12, 18, 24, and 36 months of age. At 36 months, clinical best estimate outcomes (e.g., Autism, ADHD Concerns) are determined. Using a novel eye-tracking task which I developed, I will first examine trajectories of absent reference over the first two years of life, including comparisons of absent reference trajectories between typically and atypically developing infants (Aim 1). Then, I will use micro-analytic behavioral coding to capture the degree of temporal coordination (contingency) during infant-caregiver interactions and a standardized measure of receptive and expressive language, probing absent reference as a potential mediator of the association between early social contingency and later language abilities, and exploring the possibility of moderated mediation by outcome group (Aim 2). Strategic training goals and activities have been crafted as part of the F31 proposal to fill important knowledge, skill, and experience gaps in my training through robust mentorship from experts in longitudinal studies using transdiagnostic frameworks (Miller), cognitive and language development (Xu, Thurman), dyadic interactions (Schwichtenberg), and advanced statistical procedures (Iosif). Overall, the proposed training and research plans will facilitate progress towards my long-term goal of securing a tenure-track faculty position that bridges developmental and clinical science and will lead to advancements in the fields of language development, neurodevelopmental conditions, and developmental psychopathology. Results from the proposed study will have implications for efforts aimed at detecting language difficulties earlier and for the development of targeted interventions to support language development.

NIH Research Projects · FY 2024 · 2024-07

Project summary Social anxiety disorder is the most common anxiety disorder in the United States, and ~40% of affected individuals do not respond to existing treatments. A limited knowledge of the neural circuits modulating anxiety impedes innovation for new therapeutic strategies. Recent sequencing data highlight the diversity of neuronal cell types in the brain, but a key challenge is determining how different cell types function in behaviorally relevant contexts. The answer to this question is important because many genetically defined cell types are evolutionarily conserved across humans, primates, and rodents. One way to link cell types to behavior is with activity-dependent tagging. The first methods (TRAP, tetTag) used the expression of immediate early genes to label neurons that are active in specific behavioral contexts. These systems were revolutionary, but the temporal resolution of these methods is limited (hours) while behavior can occur over minutes. The Fast Light and Calcium-Regulated Expression (FLiCRE) system combines light- and calcium-dependent tagging methods to label cells that are activated during a discrete timepoint (~10 min), when a behavior of interest is expressed. We will use the FLiCRE system to tag cells in brain regions that modulate social approach (nucleus accumbens, NAc) and avoidance behaviors (bed nucleus of the stria terminalis, BNST). We will genetically define these cells using single cell RNAseq and then functionally define them using optogenetic manipulations. We will use FLiCRE to tag cells in the BNST of mice exhibiting social avoidance and use single nucleus RNA sequencing (snRNAseq) to genetically define these cells to test the hypothesis that a subset of Oxtr cell types are active in stressful social contexts. Pharmacological activation of oxytocin receptors in the BNST is necessary and sufficient for drive social avoidance. We will then use optogenetics to functionally define these cells. We predict that inhibition of BNST cells tagged during social avoidance will increase social approach. Next, we will use FLiCRE to tag cells in the NAc of mice exhibiting social approach. We will use snRNAseq to test the hypothesis that Oxtr interneurons are active during social approach, because oxytocin receptors in the NAc promote social approach. We will then use optogenetics to inhibit these cells and predict that inhibition will decrease social approach. Our research team is ideally suited to execute these studies. Dr. Trainor's lab delineated oxytocin receptor-dependent pathways of social approach and avoidance. Dr. Kim developed the FLiCRE construct and used it to identify a novel cell type in NAc that drives aversion. Dr. Tollkuhn is a molecular biologist and expert on using single nucleus RNAsequencing in brain. Dr. Wiltgen has successfully performed optogenetic manipulations of neurons labeled via activity-dependent tagging. Our analyses will identify cell types that modulate social approach and avoidance behaviors, which could lead to novel insights into how to selectively target these cells.

NIH Research Projects · FY 2025 · 2024-07

Enter the text here that is the new abstract information for your application. This section must be no longer than 30 lines of text. Pancreatic islet dysfunction is central to type 2 diabetes mellitus (T2DM) pathogenesis and consists of both α-cell and β-cell dysfunction. The regulation of α-cell and β-cell health is determined by a complex network of paracrine regulators that are incompletely defined. To improve the treatment and prevention of T2DM, it is critical to have a complete picture of α-cell and β-cell regulation. We have identified the signaling protein, 14-3-3ζ, as an important regulator of β-cell function and crosstalk between α-cells and β-cells. Specifically, recent work from our lab demonstrates that β-cell 14-3-3ζ inhibition increases glucose-stimulated insulin secretion (GSIS) and activates α-cell active glucagon-like peptide-1 (GLP-1) production and secretion in mouse and human islets. It is increasingly evident that α-cells play an important role in the potentiation of GSIS, thereby expanding their function beyond that of the traditional counterregulatory role. Efforts to understand the role of the α-cell in the regulation of islet function have revealed both transcriptional and functional heterogeneity. Further analysis of this heterogeneity suggests that functionally distinct α-cell subpopulations display alterations in their hormone profile, with some α-cells producing active GLP-1 from the proglucagon precursor. While GLP-1 and glucagon are both able to potentiate GSIS via local actions mediated by GLP-1R and glucagon receptor expressed by β-cells, only glucagon stimulates hepatic glucose production (HGP). In effect then by switching their endocrine output from glucagon to GLP-1, α-cells favor GSIS over the stimulation of HGP. How plasticity in α-cell endocrine profile is regulated and how it impacts overall islet function is unknown. Therefore, we will test the hypothesis that β-cell 14-3-3ζ regulates GSIS by enhancing α-cell to β-cell crosstalk. Aim 1 will determine the role of α-cell GLP-1 in 14-3-3ζ regulation of islet function. To this end, we will assess GSIS in response to β-cell 14-3-3ζ inhibition in islets from wild-type mice and mice with α-cell-specific inability to produce GLP-1. Aim 2 will define the regulation of plasticity in α-cell hormone production by β-cell 14-3-3ζ. To this end, we will define the regulation of GLP-1+ α-cells induced by β-cell 14-3-3ζ ablation and determine the receptor class responsible for activation of α-cell GLP-1 production.

NIH Research Projects · FY 2026 · 2024-07

Project summary Heart failure (HF) with preserved ejection fraction (HFpEF) is a major public health burden currently affecting more than three million Americans and leading to significant morbidity and mortality. HFpEF prevalence is expected to further increase with the aging population and the concomitant diffusion of recognized risk factors such as obesity, diabetes mellitus, and hypertension. HFpEF is a complex multi-organ, systemic syndrome that drastically reduces patients’ quality of life. Importantly, patients’ survival rate after first hospitalization is very limited, as effective treatment options for HFpEF are currently inadequate. Notably, almost all therapies developed for the better characterized HF with reduced ejection fraction (HFrEF) have been shown to be ineffective in HFpEF, implying the existence of different underlying mechanisms of disease yet to be identified. The lack of effective treatment options for HFpEF is now one of the major unmet needs in the medical field and may be due also to the large phenotypic heterogeneity observed in patients. In fact, HFpEF phenotypic diversity represents an obstacle for timely diagnosis of HFpEF and is not entirely captured by most preclinical animal models and clinical trials. Sex differences are thought to contribute to this phenotypic variability. Indeed, HFpEF is more common in women, who experience worse symptoms but have lower risk of mortality than men. Overall, HFpEF phenotypic heterogeneity hampers our understanding of the mechanisms underlying altered excitation- contraction coupling (ECC) and increased propensity for ventricular arrhythmias (i.e., one of the leading causes of death among HFpEF patients). Our overarching hypothesis is that, because of the presence of different HFpEF subphenotypes, an effective therapy may benefit from a subgroup-targeted approach. We have previously demonstrated the power of mechanistic modeling and data-driven precision medicine techniques to classify and discriminate cardiac phenotypes. In this Project, we propose a novel integrative computational/experimental approach aimed at i) identifying the key molecular and cellular functional changes in HFpEF in a preclinical animal model, and ii) concomitantly investigating the impact of HFpEF heterogeneity in disease mechanisms and therapy. Informed by novel functional and transcriptomic data, we will develop a refined modeling platform that allows for new quantitative predictions amenable to experimental testing, as well as translation of experimental findings across species. In synergy with the NHLBI initiatives HeartShare and Accelerating Medicines Partnership, completion of the studies proposed in this Project will provide new mechanistic insights into HFpEF phenotypic diversity in contractile dysfunction and arrhythmogenesis and help targeting new therapeutic strategies to different subpopulations of HFpEF patients.

NIH Research Projects · FY 2025 · 2024-07

PROJECT SUMMARY: Our overarching goal is to develop a transformative integrative clinical, experimental and in silico-based pipeline to create a digital twin technology for patient-specific prediction. Digital twin technology holds the promise of the development and application of virtual models that replicate physiological processes and characteristics of diseases to reveal mechanisms, simulate disease progression, identify potential drug targets and simultaneously predict drug efficacy. While our planned approach is broadly applicable, here we will apply digital twins to the problem of identification of cardiac drug targets and prediction of the efficacy or cardiotoxicity of drugs in individuals. A major strength of our digital twin approach is that it incorporates data from the atomic structure to the cardiac rhythm, allowing the inclusion of individual differences that affect individual protein structure, cellular electrophysiology and electrocardiograms. Digital twins will allow for improved understanding of how variation between individuals modifies disease severity and drug cardiotoxicity risks. Such a technology is possible now due to the maturity of deep-learning based modeling and simulation approaches in conjunction with the increasing availability of ion channel protein structures in physiologically relevant states, and the development of patient-specific induced pluripotent stem cell-derived cardiomyocytes (iPSC-CMs). Combining these developments will allow for the realization of high throughput testing for individuals to determine their disease- and drug-related risks. Indeed, our preliminary data indicate the promise of a new deep learning method to extract in silico representations of individual cellular electrophysiology and Ca2+ handling to digitally replicate the mechanistic cellular fingerprint. We will build a new digital twin framework across multiple system scales by bringing together new methods in atomistic scale simulation with recently developed cellular level models and deep learning networks to discover new protocols to extract needed model parameters from data and for translating from iPSC-CM to adult cardiac myocyte electrophysiology. We will develop and test an experimental and computational digital twin platform applied to problem of personal cardiac disease expression and drug-induced cardiotoxicity via a combined computational-experimental approach that will allow the construction, prediction and validation of patient-specific digital twin cardiac cells. We aim to 1) Develop cardiac ion channel protein digital twins for structure and function prediction, 2) Develop cardiac myocyte digital twins, and 3) Predict the patient-specific cardiac safety pharmacology of individual drugs and combined therapeutics. We are bringing together model simulations at the level of the atom in a totally new way to include genetic mutations spanning benign variants to ones with known arrhythmia risks (from which all other models can be developed by extension) and predict their impact on drug interactions and biological function modulations at different scales. The proposed studies have the potential to conceptually transform the field by generating an integrative, high-throughput framework that predicts individual responses to disease and drugs.

NIH Research Projects · FY 2025 · 2024-07

ABSTRACT Coronavirus Infection Dynamics and Cross-species Transmission in Bats Prevention of future zoonotic disease emergence, including pandemic threats, is only possible with a thorough understanding of infection dynamics in reservoir host populations. The emergence of SARS-CoV, MERS, and SARS-CoV-2 highlight the need to examine bat-borne coronaviruses in their natural environments. Disease dynamics and cross-species transmission events in bat populations are complex and remain poorly understood, despite evidence suggesting that cross-species transmission has shaped coronavirus diversity and evolution and that viruses with broad host ranges may have increased pandemic potential. Understanding the longitudinal infection dynamics and the ecological conditions under which coronavirus cross-species transmission events occur will characterize the processes underlying virus emergence in bats. I hypothesize that coronavirus cross-species transmission dynamics are driven by host ecology and environmental conditions. In Aim 1, I will assess ecological drivers of cross-species transmission of coronaviruses in bats. Using viral surveillance data standardized across 30 countries with over 50,000 individual bats sampled, I will assess the likelihood of coronavirus cross-species transmission using an evolutionary Bayesian phylogenetic approach. Covariates examined will include host-genetic similarity, roost-type, reproductive characteristics, conservation status, and geographical home-range overlap. Cross-species transmission of bat-borne coronaviruses may play an important role in increasing the distribution of viruses and pandemic potential. In Aim 2, I will characterize longitudinal dynamics of coronavirus infections in bats in diverse roost locations. I will lead local fieldwork in California (USA) to characterize seasonality and diversity of coronavirus infections in primarily single-species roosts. In Myanmar, I will collaborate with an international team to examine longitudinal dynamics and additionally assess risk factors for coronavirus positivity. The coronavirus and ecological data generated will help parameterize models to understand the role of cross-species transmission in outbreak thresholds, thereby revealing mechanism underpinning viral emergence. My proposed work has specific relevance towards understanding the dynamics underlying the origins of SARS- CoV-2 and could inform on future pandemic threats. This study will provide actionable insights into public health risks, especially for local communities that are most likely to be first exposed to emerging diseases.

NIH Research Projects · FY 2025 · 2024-07

Project Summary: The UC Davis REsearch to Advance Connected and Community Health Equity (ReACH Equity) Predoctoral Training Program Plan The UC Davis ReACH Equity predoctoral training program responds to NINR’s call to action to address the impacts of societal inequities in health and healthcare by training a new generation of scientists to employ advanced, multidisciplinary, multi-level methods to improve health equity. We will provide a rich training environment for 26 predoctoral trainees to establish the evidence base for improving health equity across the lifespan among historically and presently marginalized communities (HMCs) through research at the systemic/policy, community/services, and family/individual levels. The objectives are to: 1) recruit and retain a diverse group of predoctoral trainees who conduct rigorous, innovative, equity-focused research in prevention science and population health; 2) empower ReACH Equity trainees to make informed decisions about the breadth of research-focused career paths, including academia, public policy, and industry; and 3) educate trainees in multidisciplinary approaches to equity-focused prevention science and population health, including core doctoral competencies (e.g., conceptual knowledge, developing important research questions, community engagement, all facets of study design, implementation, evaluation, and dissemination, and professional development). These objectives are accomplished in a carefully structured program that leverages the expertise of 50 mentors, the majority of whom are underrepresented in science, from 17 individual Departments in three Colleges, the Betty Irene Moore School of Nursing, and the School of Medicine on both our Sacramento and Davis campuses. These mentors’ expertise cuts across the disciplinary spectra (e.g., nursing science, human development, psychology, sociology, nutrition, computer science, public health sciences, health policy), focuses on a wide variety of HMC populations, and addresses inequities from prenatal populations through older adults. We will use the peer-onsite-distance model of mentoring, where trainees will be matched to a primary mentorship team that includes one experienced mentor and one mentor-in-training; this team will serve as their content experts. Each cohort also will have a cohort mentor to facilitate group and peer mentoring. Trainees will engage in didactic and experiential learning that will provide them with the core competencies and in-depth theoretical knowledge required for successful careers in health equity by ensuring that advances in equity-focused prevention science and population health are utilized among HMCs. We will engage in continuous quality improvement through ongoing internal evaluation of processes and outcomes, as well as reviews from an external advisory board and a local community advisory board comprised of patients and families. The disciplinary diversity combined with expertise mentoring individuals from HMCs among our pool of mentors will support trainees to invoke research questions that enable collaboration with a multidisciplinary team of investigators to elucidate the complex interplay of factors that contribute to health inequities, and then to use multiple perspectives and methodologies to identify sustainable solutions.

NIH Research Projects · FY 2025 · 2024-07

PROJECT SUMMARY Few structures in the brain are as prominent, yet poorly understood, as the pulvinar. The pulvinar is both large and complex, having undergone more expansion with primate evolution than any other thalamic nucleus. Based on its reciprocal connections with the full extent of the visual hierarchy, from primary visual cortex through inferotemporal cortex, the pulvinar is strategically positioned to facilitate/mediate the communication of visual signals between cortical areas. These transthalamic pathways operate in parallel to the direct corticocortical pathways. The main goal of this research is to understand the functional organization of the separate direct and transthalamic pathways that cortical areas use to communicate with one another. For this, we use the mouse and monkey visual systems and study the connections between the primary and secondary visual cortical areas (V1 and V2) in each species. We use optogenetic tools to selectively inhibit one or the other pathway from V1 to V2. We study the effects of such inhibition on the animals’ ability to perform various visual tasks as well as on responses to visual stimulation among V2 neurons. A major goal is not only to identify functions for the direct and transthalamic pathways, but also to compare these among such disparate mammalian models as mice and monkeys with the hope of generating insights into the functioning of these cortical processes that are common to mammals. Given the severe financial and quality-of-life consequences that follow from disruption in the ability of cortical areas to communicate properly with each other, such as occurs with many forms of epilepsy, stroke, and illnesses affecting vision and thalamocortical function, it is important that we understand how the thalamus and cortex interact to meet the processing needs of the brain. The proposed study will have a major impact on our understanding of higher order thalamus, cortical communication, and substrates for disease and dysfunction.

NIH Research Projects · FY 2025 · 2024-07

This application is submitted in response to PAR-23-040 with the goal of integrating cutting-edge in vivo imaging technologies and key immunologic assessments to enhance the rigor and reproducibility of translational nonhuman primate models for genetic and regenerative therapies. The proposal meets the objective of PAR-23-040, which is focused on “…developing and implementing broadly applicable technologies, tools, and resources for...enhancing rigor, reproducibility, and translatability of animal research”. We will support translational research by incorporating total-body positron emission tomography (PET) and correlative assessments of the immune system. The investigations proposed will enhance the rhesus monkey model system by creating or improving study protocols that provide a high level of sensitivity and reproducibility for assessments that are important to clinical translation. The Specific Aims are: (1) Use total-body PET imaging to longitudinally monitor gene transfer and biodistribution in preclinical studies of fetal or juvenile rhesus monkeys for clinical translation, and (2) Explore new readouts of immune responses to innovative therapeutics in tissue sites using T-cell tracking in translational nonhuman primate studies. These investigations will address relationships between local T-cell infiltration and circulating immunophenotypes with correlative in vivo imaging, which will enhance models and provide new methods to assess the primate immune system. Monitoring inflammation and immunity in targeted and non-targeted tissues is critically important to ensure safety as new therapeutics transition to the clinic for a range of common and rare diseases. These studies will provide predictive protocols and tools which will inform preclinical and IND- enabling studies for future human applications across age groups.

NIH Research Projects · FY 2025 · 2024-07

Project Summary. Our ability to internally sense body and limb position, referred to as proprioception, is essential for purposeful movement and is known to be impaired in a variety of conditions such as amyotrophic lateral sclerosis, peripheral neuropathy, and aging. Conversely, activation of peripheral proprioceptive pathways promotes recovery from spinal cord injury, highlighting the translational relevance of understanding how proprioception is encoded. Proprioceptors, the sensory neurons that initiate proprioceptive signaling, require Piezo2 to transduce muscle movement into electrical signals for normal motor function. What happens downstream of Piezo2 activation is debated. We will address a fundamental yet unanswered question in the field of sensory-motor neuroscience: how do voltage- gated sodium channels (NaVs) shape proprioceptor function in sensory-motor circuits? Mammalian proprioceptors express three NaVs: NaV1.1, NaV1.6, and NaV1.7. Our lab has published the only functional evidence to date on the contributions of any NaV to mammalian proprioception. Because the genetic access point to proprioceptors is parvalbumin, a protein also expressed in brain and spinal cord neurons, we used a sensory-neuron wide genetic targeting strategy that spares the confounding factors associated with NaV deletion in the central nervous system. We reported that loss of the NaV1.1 isoform results in inconsistent proprioceptor coding of sustained muscle stretch and visible motor behavior deficits. Our new pilot data support the notion that while NaV1.1 is tasked with maintaining reliable proprioceptive transmission, the NaV1.6 isoform is tasked with initiating proprioceptive signaling. The role of NaV1.7 in shaping proprioceptive signaling remains unknown and will be directly investigated for the first time in this proposal. We will leverage inducible conditional knockout mouse models to systematically delete individual Navs after proprioceptor development and investigate how NaV1.1, NaV1.6, and NaV1.7 distinctly contribute to mammalian proprioception. Using a combination of behavior and mechanistic in vitro patch-clamp electrophysiological experiments, we aim to determine how acute disruption of NaV expression post-weaning impacts motor behaviors, and will also identify NaV subtype-specific biophysical features that govern proprioceptor excitability. These studies will be complemented by quantitative immunohistochemistry and super-resolution imaging to identify the cellular localization of each NaV isoform within proprioceptors. We will also use ex vivo muscle-nerve recordings and optogenetics to define how NaVs expressed in proprioceptors individually shape peripheral neurotransmission, which will inform interpretation of our behavioral analyses. Finally, we will determine which NaVs are essential for proprioceptor synaptic transmission in central circuits using two different ex vivo spinal cord electrophysiology preparations. Collectively, this work will advance our fundamental understanding of mammalian proprioception and illuminate the specific and distinct roles of NaVs in sensory-driven motor behavior, which will contribute new insights into neurological conditions in which proprioception is impaired.

NIH Research Projects · FY 2025 · 2024-07

Enter the text here that is the new abstract information for your application. This section must be no longer than 30 lines of text. The primary goal of the UC Davis enhanced Molecular, Cellular, and Developmental Biology (eMCDB) Training Program is to ensure the success of our predoctoral Trainees in graduate school and prepare them for impactful careers in the biomedical workforce by nurturing productive, rigorous, resilient scientists and confident communicators. A secondary goal of the eMCDB Program is to enhance the training and career development of a broad cohort of PhD students at UC Davis by extending our activities beyond our Program. A dynamic and experienced team of 63 Faculty Trainers from 18 academic departments will provide our training. These trainers, carefully selected from the top molecular, cellular, and developmental biologists on campus, offer wide-ranging interdisciplinary training in basic and translational life science research. Each has an active research program, a successful track record of mentoring, and a commitment to fostering safe and supportive training environments. Trainees are selected from the most qualified graduate students across five affiliated Graduate Groups through a comprehensive process. Training is accomplished by integrating Graduate Group coursework and mentored PhD dissertation research in individual laboratories with a coherent set of curricular and training activities developed by this Program to support each Trainee’s growth along five skillsets critical for graduate training and lifelong career progression: scientific rigor, communication, wellness and resilience, mentoring, and career development. The effectiveness of our Program’s activities will be regularly and rigorously evaluated to allow Program leadership to adapt and ensure that Program goals are met. Institutionally, UC Davis has made major commitments to establish a vibrant faculty and cutting-edge infrastructure to support research in molecular, cellular, and developmental biology. The substantial institutional support allocated to this Training Program further reflects our shared goals to deliver outstanding, high-quality graduate training for eMCDB Trainees and our commitment to support the development of the national biomedical research workforce.

NIH Research Projects · FY 2025 · 2024-07

Summary: The overall goal of the proposal is to determine the role of the medial temporal lobe (MTL) in visual perception and working memory. Although it is well established that the MTL is critical for long term episodic memory, recent work has indicated that it also plays a critical role in visual perception and working memory, and that damage or age-related changes to this brain region can disrupt our ability to accurately perceive the visual world around us, particularly when encountering complex scenes such as when driving a car. However, the specific role that the MTL plays in supporting visual perception is just beginning to be fully understood, and there is now a growing debate about when these deficits will be observed, and which underlying brain processes are responsible. Answering these questions will have a transformative effect on our understanding of visual cognition, and advance our knowledge about how various diseases influence the human brain. In addition, they have important translational implications for a variety of populations suffering from damage to different regions within the MTL such as patients with Alzheimer’s Disease, Schizophrenia, depression, and even in healthy aged individuals. The current proposal will address these questions using a unique combination of psychophysical methods, novel eye tracking approaches, studies of patients with focal MTL lesions, and high-resolution brain imaging methods in healthy subjects. Psychophysical methods will be used in ‘same/different’, ‘change-detection’ and ‘flicker’ visual discrimination tasks for scenes and objects in order to separate the processes involved during initial feature sampling and those involved in supporting subsequent change detection, as well as allowing us to track how these processes change as more information is sampled from the environment. The series of studies is designed to directly test the predictions of competing theories, and, when possible, we pit the predictions of these different accounts against one another. We will examine performance in healthy controls and in patients with focal MTL lesions in order to determine whether regions in the MTL such as the hippocampus play a critical role in various perception conditions. Moreover, we will utilize high-resolution functional magnetic resonance imaging to identify the role of hippocampal subfields as well as the broader brain networks involved in perception. Importantly, these methods will be combined with novel analytic approaches to quantifying eye movements to determine how the visual system samples information from the environment (e.g., examining saccadic dispersion, visual resampling, as well as meaning- and salience-sampling), and using novel fixation-related brain imaging methods to identify the neural circuitry that is critical for accurate visual perception.

NIH Research Projects · FY 2025 · 2024-07

Project Summary Human herpesvirus 6A and human herpesvirus 6B, collectively termed HHV-6A/B, are ubiquitous viruses that permanently infect most humans from an early age. Initial HHV-6A/B infection mainly occurs from the contact of infected saliva or nasal mucus with the respiratory tract. However, HHV-6A/B genome can be maintained generation to generation through inheritance, which is mediated by the integration of HHV-6A/B genomes into the telomeres of host cell chromosomes. Inherited chromosomally integrated human herpesvirus 6 (iciHHV-6) is seen in 1-2% of European and US populations and 0.6% of people in Japan. In these human populations, the HHV-6 genome is integrated into the telomere of a single chromosome in every nucleated cell in the body. These integrated viruses reactivate from the integrated chromosome to produce viral progenies. Reactivation of iciHHV- 6 is suggested to be associated with many disease developments that include encephalitis, spontaneous abortions, pre-eclampsia, angina pectoris, and exacerbation of graft-versus-host disease following hematopoietic stem cell transplantation. Accumulating evidence has also suggested the neurovirulence of HHV- 6A/B infection with several important neurological disorders. In particular, evidence indicates that HHV-6B reactivation can cause acute limbic encephalitis in immunocompromised patients, and frequent viral reactivation cycles result in temporal lobe epilepsy. However, a lack of suitable in vitro models to evaluate HHV-6A/B reactivation from the integrated viral genome in neural cells, limits our study designs. This is because, for diseases of the central nervous system, the affected tissue is challenging to access for study in living patients. Such in vitro tissue culture models will examine risks of harboring iciHHV-6 in disease developments and facilitate molecular analysis of iciHHV-6 reactivation/replication from integrated host chromosomes. Like other virology research, establishing an in vitro culture model is vital to identify essential cellular or viral targets for further therapeutic development. Here, we request funding to establish cell models to study iciHHV-6 reactivation. We will generate induced pluripotent stem cells (iPSCs) and differentiate them into neural stem cells. With the established resources, we will examine how and when iciHHV-6 reactivation is triggered. We will test what physiological cell differentiation processes trigger iciHHV-6 reactivation. We will complete the tasks with ongoing international collaboration, and develop essential resources for HHV-6A/B researchers.

NIH Research Projects · FY 2025 · 2024-07

Project Summary The cardiac cycle starts with the production of an action potential (AP) by pacemaking cells in the sino-atrial node (SAN), initiating the propagation of electrical signals that trigger atrial and ventricular contraction. We have discovered that the organization of the SAN microvasculature varies regionally, a variability that serves to match blood supply to local myocyte excitability. These observations have led us to propose a new model for the metabolic control of excitability and cardiac pacemaking activity. In our model, the highly vascularized superior SAN is populated by myocytes capable of undergoing periodic voltage oscillations, some of which do not reach AP threshold. Despite these failures, the many oscillations that do reach threshold can still enable superior SAN myocytes to exhibit a high intrinsic AP firing rate, even if their periodicity is not optimal. By contrast, inferior SAN myocytes are sparsely vascularized and have a low AP firing rate. Importantly, inferior SAN cells produce stochastic subthreshold electrical signals. We propose that, when these subthreshold events coincide with an electrical signal from the more periodic voltage oscillator in the superior SAN, the subthreshold signal events integrate and, at their peaks, increase the probability of the superior SAN crossing the threshold and generating an AP. Accordingly, inferior SAN cells that produce these random electrical signals act through a stochastic resonance mechanism to increase the strength and periodicity of superior SAN activation. A key feature of our proposed conceptual model is that inferior SAN myocytes do not fire APs at high frequencies for prolonged periods of time because they do not generate ATP at the rate necessary to sustain a high level of electrical activity. Consistent with this, we discovered that, contrary to the prevailing view, APs induce rapid fluctuations in ATP levels in SAN myocytes, indicating that electrical activity has an impact on the energetic reserve of myocytes. Thus, a combination of regional variations in vascular supply and ATP dynamics help deterimine superior and inferior SAN excitability. We will test the hypothesis that changes in vascular supply to the node impact myocyte ATP dynamics, excitability and, hence, pacemaking activity during the development of heart failure. A central premise of this project is that vascular supply, pacemaking activity, and ATP dynamics in SAN myocytes are inextricably intertwined. The project will test the physiological and pathological implications of our conceptual model with three specific aims. Specific aim 1 tests the hypothesis that stochastic resonance increases the periodicity of SAN myocytes. Specific aim 2 tests the hypothesis that ATP consumption fluctuates in SAN myocytes in a beat-to-beat fashion and varies regionally. Specific aim 3 tests the hypothesis that changes in vascular supply to the SAN, as well as myocyte ATP dynamics and stochastic resonance, contribute to alterations in pacemaking activity during the development of heart failure. The proposed studies offer an alternative to the predominant entrainment pacemaking paradigm and have the potential to radically transform our understanding of how the excitability of SAN myocytes is regulated in health and disease.