University Of South Carolina At Columbia

NIH Research Projects · FY 2025 · 2019-01

PROJECT SUMMARY Precise wiring of axonal projections into topographic maps facilitates the transfer of information between brain regions and is thus critical for brain function. An important mechanism contributing to topographic map for- mation is pre-target axon sorting, whereby axons become topographically ordered along tracts before they reach their target. In the visual system, for instance, dorsal and ventral retinal axons respectively segregate into the ventral and dorsal branches of the optic tract before reaching the tectum. While pre-target axon sorting has an instructive role in topographic mapping, how it is established during development remains poorly under- stood. Using the unique transparency and accessibility of the zebrafish embryo, we previously showed that axon sorting in the visual system is achieved by a pruning mechanism that eliminates axons that missort along the optic tract. Whereas ventral axons never misroute, some dorsal axons wrongfully navigate along the dorsal branch of the tract but then stop and rapidly degenerate. Our new results further demonstrate that pioneer ven- tral axons instruct the degeneration of the dorsal axons that missort, demonstrating that axonal pruning is initi- ated by signaling among growing axons themselves. The heparan sulfate proteoglycan Glypican-3 (Gpc3) and the adhesion molecule Teneurin-3 (Tenm3) act cooperatively along pioneer ventral axons to induce the degen- eration of missorted dorsal axons. On the other hand, the adhesion G protein-coupled receptor (GPCR) Latro- philin 3.1 (Lphn3.1) signals cell-autonomously along missorted dorsal axons to initiate their pruning. While our studies uncovered a unique trans-axonal signaling for selective axon pruning, several important questions re- main unsolved. First, the mechanism by which Tenm3 and Gpc3 instruct axonal pruning remains unknown. Missorted dorsal axons elongate in the wrong branch for several hours before stopping and degenerating, indi- cating that they become responsive to Tenm3 signaling. Here, we will test the hypothesis that Gpc3 initiates this temporal response by controlling the onset of Tenm3 signaling from ventral axons. We will use a combina- tion of biochemical, genetic and high resolution imaging approaches to test whether Gpc3 interacts with Tenm3 in a heparan sulfate-dependent manner and regulates its trafficking to, or processing at, the plasma membrane of ventral axons. A second question is how Lphn3.1 instructs selective axon pruning. It remains unknown how Lphn3.1 signals and whether its function is specific or shared by other latrophilins. Here, we will test whether other latrophilins can compensate for the loss of Lphn3.1, and identify which features of Lphn3.1 are necessary for its activity. Finally, we will explore which signaling pathways act downstream of Lphn3.1 by testing whether Cyfip2, a cytoplasmic protein required for pruning missorted dorsal axons, mediates Lphn3.1 signaling. Alto- gether, our proposed studies will be the first to determine how trans-axonal signaling between pioneer and fol- lower axons establishes pre-target axon sorting in the visual system. They will fill a major gap in our knowledge of developmental axon pruning and tract formation, two processes essential for precisely wiring neural circuits.

NIH Research Projects · FY 2025 · 2018-09

Since the early 1990s, the field of childhood obesity has known that children gain 3-5 times more weight during their 3-month summer vacation than they do during the entire 9-month school year. Evidence shows that youth from low-income households are especially vulnerable to accelerated BMI gain during the summer. The cohort study we seek to extend in this renewal R01 is What’s UP (Undermining Prevention) with Summer. This is the largest and most diverse study of elementary-age children designed to understand accelerated BMI gain during the summer. In this R01, children are measured on key obesity-related health behaviors (i.e., activity, sleep, screen time, time spent sedentary, and diet) during school year (April/May) and in the summer (July). What’s UP with Summer advances the field of accelerated BMI gain during the summer by 1) measuring the SAME children during school and again during summer over multiple years using a within-person design; 2) measuring height/weight at the beginning and end of each summer over time to examine changes in BMI gain during the school year and compare this to BMI gain during the summer; and 3) leveraging rich time/date stamped 24hr accelerometry data and combining this with daily time diary recordings of where children are, what times they are there, when and what they eat, and who they are with. Accelerated BMI gain is not a phenomenon that occurs only in elementary-age children. Suggestive, yet limited, data suggest that middle and high school- age youth also exhibit accelerated BMI gain during the summer. Unlike elementary-age children, important differences in autonomy and decision making occur during these formative adolescent years. The major gaps in the science are few studies measure key health behaviors during the school and summer in middle and high school youth and limited information exists about the social and setting contextual influences on middle and high school health behaviors over the summer and how they impact changes in BMI. Without information collected as proposed in this renewal application, the ability to design effective public health interventions to address obesity during the summer for adolescents is severely limited. In this R01 we will compare longitudinal changes in BMI z-scores and health behaviors during school and summer and from elementary school to high school, identify individual, peer, family/home, neighborhood, and school/community influences on BMI z-scores and health behaviors during school and summer from elementary school to high school, and qualitatively explore changes in adolescents’ BMI and health behaviors during the summer and school. This project is significant because it will extend a well-established existing cohort to identify the impact of an understudied timeframe (summer) associated with accelerated BMI gain during a developmental period for which no information exists (adolescence). This project is innovative because it will capture information on the same youth during school and summer, follow them over time, and collect contextually rich information to understand and identify modifiable factors to inform the design of behavioral interventions.

NIH Research Projects · FY 2026 · 2018-04

ABSTRACT Food insecurity affected 11% of all US households in 2020, and youth and young adults with type 1 diabetes (T1D) or type 2 diabetes (T2D) experience even higher rates of food insecurity, 18% and 31%, respectively. Moreover, 56% of youth and young adults with T1D and 46% of those with T2D do not achieve optimal glycemic control, with young people from some population groups experiencing much higher rates of poor glycemic control. We propose a continuation of the NIDDK-funded SEARCH Food Security Cohort Study (SFS 1), which collected data on >1,000 youth and young adults with diabetes and documented the role food insecurity plays in influencing glycemic control and related outcomes. SFS 1 data indicate that compared to those who are food secure: (a) young people with T1D and food insecurity have higher HbA1c (+0.34%, p=0.04) and (b) those with T2D and food insecurity have higher odds of diabetic ketoacidosis (3.1, p=0.02) in fully adjusted models. However, food insecurity varies day-to-day and ranges from intermittent to persistent, and SFS 1 did not capture the day-to-day variation, which is needed for intervention planning. Thus, we propose a research strategy of high scientific rigor that will integrate longitudinal quantitative and qualitative methods, including ecological momentary assessment (EMA) and continuous glucose monitoring (CGM), in an intensive, mixed methods study. This proposal (SFS 2) greatly expands our work in SFS 1 toward identifying the temporal causal cascades and actionable and acceptable interventions for eliminating food insecurity. To achieve these goals, we aim to (1) leverage the ongoing SFS 1 study to enroll a cohort of 360 youth and young adults with diabetes (260 T1D, 100 T2D), 72% with a history of food insecurity, for a repeated-measures, longitudinal mixed methods study over 9 months; (2) evaluate differences in real-time glycemic control between participants with varying levels of food insecurity, assessed by average daily time in range (TIR) via CGM over two 14-day time periods spaced 9 months apart; (3) evaluate the within-participant impact of food insecurity on TIR and intermediate paths using EMA methods, including dynamic structural equation models; (4) use longitudinal, qualitative methods to concurrently and deeply characterize the context of participants’ food insecurity experience and coping process, by conducting a concurrent events study of 30 individuals with T1D and 15 with T2D with a history of food insecurity through in-depth, one-on-one, repeated semi-structured interviews over 9 months. This study will integrate intensive data collection of the primary outcome (TIR by CGM) and the primary exposure (daily food insecurity), as well as measures of physical activity, diet, and mood. These quantitative data will be complemented by longitudinal qualitative interviews, which will allow us to triangulate the quantitative data with participants’ lived experiences. The findings will contribute to future interventions and policies that are designed to interrupt the cycle of food insecurity and poor glycemic control and are effective for and acceptable to young people with diabetes.

NIH Research Projects · FY 2025 · 2016-09

PROJECT SUMMARY/ABSTRACT Anxiety is the most common pediatric mental health problem, affecting ~10% of children and adolescents1. Given the substantial prevalence and impact of anxiety, recent interest has focused on characterizing anxiety within high-anxiety-risk clinical subgroups (e.g., neurodevelopmental disorders) to provide critical insight into the specific risk factors, developmental pathways, and consequences of anxiety. Individuals with fragile X syndrome (FXS) constitute one such high-anxiety-risk subgroup, with up to ~80% of adolescents and adults meeting criteria for at least one anxiety disorder16. Work from our initial NIMH-funded R01 demonstrated that anxiety emerges early in childhood in FXS, with 39% of preschoolers diagnosed with at least one anxiety disorder17, and increases in severity across early childhood. The first funding period of this R01 (2016-2023) was highly successful (26 papers to date) in characterizing the emergence, stability, and prevalence of anxiety longitudinally across early childhood (3, 4, and 5-7 years) in children with FXS contrasted to children with idiopathic (i.e., non-syndromic) autism spectrum disorder (nsASD) and neurotypical (NT) children. However, this work has fueled a new set of questions regarding the developmental trajectory of anxiety symptoms and diagnoses from early to middle childhood in FXS which are crucial to identifying the stability and consequences of anxiety in FXS across critical early developmental periods when intervention is known to be most effective. To address these gaps, this competitive renewal application will leverage our existing, rich, multidimensional longitudinal dataset and follow our existing cohort of children with FXS, children with nsASD, and NT children through 8-10 years, as well as recruit a new large cross-sectional cohort of 8-to-10-year-olds. The specific aims are to (1) Determine change in anxiety symptoms and diagnoses from 3-10 years of age in FXS contrasted to children with nsASD and NT children; (2) Document the extent to which potential early risk factors predict change in anxiety symptoms and diagnoses in children with FXS contrasted to children with nsASD and NT children; and (3) Identify (a) rates of anxiety symptoms and diagnoses, (b) functional impairment associated with anxiety, and (c) sex differences in children with FXS contrasted to children with nsASD and NT children during middle childhood. This study is innovative in its inclusion of an IQ-matched nsASD contrast group, which will answer critical questions on syndrome specificity and amplify our impact by generating knowledge on the development, predictors, and consequences of anxiety in children with nsASD and intellectual disability. This work is significant in that it will greatly expand our understanding of anxiety in FXS by providing critical information about the developmental course, predictors, and consequences of childhood anxiety, which will inform the timing and targets of intervention that will improve quality of life for children with FXS and their families.

NIH Research Projects · FY 2026 · 2016-05

PROJECT SUMMARY Iron and thiol redox homeostasis have interdependent roles in cellular metabolism. Iron serves as a cofactor for a wide variety of proteins and enzymes in essential biochemical pathways, but excess iron can be damaging to cells by catalyzing formation of reactive oxygen species that disrupt thiol redox homeostasis. Intracellular thiol- disulfide balance is critical, in turn, for the activity of proteins with functionally important cysteine residues, which includes many Fe-binding proteins. The tripeptide glutathione (GSH) and glutaredoxin (Grx) proteins function together in both thiol redox control and iron homeostasis by facilitating redox reactions and participating in iron- sulfur (Fe-S) cluster biogenesis pathways. Our previous work in the non-pathogenic yeast S. cerevisiae and S. pombe have revealed the molecular mechanisms by which a subclass of Grxs, known as monothiol Grxs, bind and deliver GSH-ligated Fe-S clusters to communicate iron bioavailability to the transcription factors Aft1/Aft2 in S. cerevisiae and Php4 in S. pombe that regulate iron acquisition and utilization pathways. Furthermore, we have used molecular genetics and cell biology approaches coupled with in vivo redox measurements via genetically- encoded fluorescent redox sensors to characterize GSH subcellular trafficking pathways that impact both iron homeostasis and redox regulation in S. cerevisiae. Here we will extend these findings by studying the impact of GSH and Grxs on the Fe-S binding properties and DNA binding affinity of the S. pombe transcription factor Fep1 that represses Fe uptake pathways during iron repletion. Furthermore, we will define the molecular details of iron regulation pathways in pathogenic yeast (Candida glabrata, Candida albicans) that express homologs of monothiol Grxs, Aft1/2, Fep1, and Php4, but for which little mechanistic information is available. In parallel, we will characterize GSH:GSSG flux between subcellular compartments in yeast cells and measure the impact of GSH deficiency, excess, or impaired trafficking on essential metal metabolism. Our innovative approach to accomplish these goals is to combine yeast molecular genetics and cell biology techniques with biochemical, structural, and biophysical methods (UV-visible absorption and CD spectroscopy, EXAFS, X-ray crystallography, Mössbauer, EPR, and single cell ICP-TOF-MS). The in vitro biochemical, structural, and biophysical studies will be used to probe protein-protein, metal-protein, and protein-DNA interactions in iron sensing pathways to uncover the molecular details of iron signaling and to monitor single cell metallomic changes in yeast populations in response to alterations in iron or GSH metabolism. The genetics and cell biology studies test how these molecular interactions and metallome changes influence the in vivo functions and dynamic localization of iron signaling and GSH metabolism factors. Overall, this multidisciplinary research program is designed to tease out the mechanistic details of iron regulation and subcellular thiol redox control at the cellular and molecular level. By studying both pathogenic and non-pathogenic fungi we will compare and contrast different strategies for adapting to redox perturbations and high/low iron environments.

NIH Research Projects · FY 2025 · 2016-04

Summary: Overall section Stroke is the leading cause of adult disability in the United States, making it a major public health concern (1). Approximately a quarter of all chronic stroke survivors present with aphasia, a language disorder caused by damage to the speech and language areas of the brain (3, 4). In a recently published report, Simmons-Mackie (1) estimates that over two million people in North America are currently living with aphasia. Stroke is typically thought to affect older persons; however, the incidence of stroke in younger individuals has been steadily increasing (2). In fact, at least half of all stroke patients in the state of South Carolina are under the age of 60 (2). Aphasia can vary in severity from very profound impairment that renders patients mute and without the ability to understand others’ speech, to milder forms where patients have great difficulty retrieving specific words. In the chronic stage of stroke, aphasia has been identified as the strongest predictor of poor quality of life. Aphasia not only influences the ability to communicate with family and friends, but also drastically decreases education and employment opportunities. Although some degree of spontaneous recovery from aphasia is typical in the first weeks and months following stroke, many patients are left with devastating communication problems and never fully recover. To address the need for studies improving long-term outcomes in aphasia, the Center for the Study of Aphasia Recovery (C-STAR), funded for just under four years at the time of this application, has made great progress towards understanding the mechanisms that promote spontaneous and therapy-induced recovery in aphasia. The overarching goal of the research proposed in this renewal application is to maintain our focus on aphasia therapy. Specifically, during the next funding phase, the focus of C-STAR is to improve access to aphasia therapy, enhance the effect of behavioral aphasia therapy to promote an improved aphasia therapy outcome, and understand overall health and neurolinguistic factors that influence aphasia recovery. To accomplish our research goals, this project will continue to rely on collaboration among five main investigators: Drs. Julius Fridriksson, Argye Hillis, Leonardo Bonilha, Chris Rorden, and Greg Hickok. Projects led by Fridriksson (chronic patients) and Hillis (acute patients) will continue to focus on factors that may promote improved outcome of aphasia therapy. Both projects have proven successful in yielding a vast, unique dataset including measures of brain status and response to aphasia therapy. Relying on this dataset, Bonilha and Rorden’s project will focus on the relationship between brain health and recovery from aphasia, whereas Hickok will utilize the same data to better understand aphasic impairment in relation to aphasia therapy success as well as new neurolinguistic models of speech and language processing.

NIH Research Projects · FY 2025 · 2015-09

SUMMARY This application asks how localized mRNA stability modifies axonal regeneration capacity, focusing on contributions of the RNA binding protein [RBP] KHSRP. The nervous system makes extensive use of post- transcriptional mechanisms to regulate cellular proteomes in response to extracellular stimuli and physiologic environments during development, function, & in response to axonal injury. Since one mRNA can be translated into protein many times over, how long a given mRNA is available for translation impacts the amount of protein generated from that mRNA. Stability of mRNAs is indeed regulated, with interactions with RBPs stabilizing & destabilizing different mRNAs, as well as interactions with microRNAs targeting some targets for degradation. Translation of mRNAs clearly supports axon regeneration, but we have little knowledge for how stability of axonal mRNAs is locally regulated. We have shown that the RBPs HuD (also called ELAVL4) and KHSRP (also called FUBP2, MARTA1, & ZBP2) compete for binding to neuronal mRNAs with AU-rich elements, where HuD interaction stabilizes and KHSRP interaction destabilizes target mRNAs. At the molecular level, this interaction is impacted by an mRNA’s affinity for binding to HuD or KHSRP. Our work over years 01-05 show that loss of KHSRP increases KHSRP target mRNA levels, causes excessive axonal and dendritic growth, impairs memory consolidation in hippocampus & prefrontal cortex, and increases presynaptic activity in prefrontal cortex and hippocampus. KHSRP is expressed into adulthood, and we surprisingly find that axonal KHSRP levels rapidly increase in peripheral nerves after injury. This increase in axonal KHSRP occurs through intra-axonal translation of its encoding mRNA. Our preliminary data indicate that KHSRP knockout mice show accelerated nerve regeneration pointing to axon-intrinsic functions for KHSRP in regeneration. Based on these observations, we hypothesize that axonal KHSRP controls the rates of axon regeneration through regulation of localized mRNA stability. We will test this hypothesis with the following specific aims: 1) Does KHSRP regulate PNS axon regeneration through a neuron intrinsic mechanism? 2) Does increased axonal KHSRP limit axon regeneration by destabilizing axonal mRNAs encoding regeneration-associated proteins? and 3) Does KHSRP’s protein interactome influence its intra-axonal functions? Completion of the studies here will begin to fill this knowledge gap by focusing on RNA-protein interactions initiated in axons that can affect mRNA survival. This will provide the first subcellular analyses of RBP domain-specific RNA regulons and will bring the first systematic assessment for contributions of RNA survival to peripheral nerve regeneration.

NIH Research Projects · FY 2025 · 2015-08

The primary neurotransmitter hallmark of Alzheimer’s Disease (AD) is a loss of acetylcholine, produced by neurons of the basal forebrain cholinergic system (BFCS). Cholinergic cell loss or dysfunction is also a prominent component of Lewy Body Dementia and vascular dementia, respectively. Thus the BFCS contributes to several aspects of cognitive function that are negatively impacted in AD and related dementias, including attention, learning and memory. Regulation of the BFCS by afferent inputs, including those from the hypothalamus, is important for integration of homeostatic and cognitive functions. Because homeostatic and physiological disturbances, such as altered food intake or sleep-wake cycles, often precede and predict cognitive decline in AD, understanding these interactions may lead to novel points of intervention to treat or delay cognitive decline in conditions such as AD. An important source of this afferent regulation is the hypothalamic orexin/hypocretin neuropeptide system, which activates cholinergic neurons in response to stimuli that signal physiological valence. We have previously shown that aging, the strongest risk factor for AD, is associated with reduced orexin expression. Recently, orexin transmission has been shown to play a role in limiting neuroinflammation, suggesting that a diminished orexin system in aging may promote neuroinflammatory processes that further negatively impact cholinergic-dependent signaling and cognition. In this renewal application, we will dissect the mechanisms underlying the association between loss of orexin signaling, neuroinflammation and subsequent cholinergic dysfunction and neurodegeneration in an aged rodent model using virus-mediated gene transfer, neurochemical, pharmacological and cognitive behavioral approaches. We will further test the hypothesis that chronic restoration and maintenance of orexin function beginning in early aging will preserve the integrity of the BFCS by modulating local microglial dynamics. The proposed studies will begin to delineate the mechanisms by which age-related loss of orexin signaling drives cholinergic dysfunction and cognitive decline and suggest the potential for orexin-targeted therapies in preventing or ameliorating AD or related dementias, all of which are characterized by neuroinflammation and cholinergic dysfunction.

NIH Research Projects · FY 2024 · 2014-07

Summary Sex and gender differences in aging and other health outcomes are frequently severely confounded by behavioral and environmental factors, mandating the use of animal models. Epigenetic age estimators provide a powerful tool in determining the epigenetic age alleviating the necessity of monitoring cohorts of animals throughout their lives in captivity or in the wild. The present study, by using outbred deer mice (Peromyscus) will explore how genetic relatedness of parents, history of social interactions, and CDK8/19 inhibition impact epigenetic age. The study relies on preliminary data indicating differences in the rate of epigenetic aging between males and females upon these interventions. Mechanistically, to link genetic relatedness with aging we will focus on the induction of endoplasmic reticulum (ER) stress, that reportedly differs between men and women. For our studies both monogamous and polygamous Peromyscus will be used. Specifically, we will (a). test if ER stress in females is more dependent on overall heterozygosity status than in males. Peromyscus male and female offspring of parents that differ in their genetic relatedness, as well as fibroblasts cultured in vitro, will be evaluated for ER stress and the resulting UPR, by analyzing the levels of a roster of chaperones that reflect ER stress. For our analysis we will utilize animals from all different stocks of Peromyscus as well as F1 hybrids between different stocks and species. (b). we will explore how the biobehavioral environment impacts epigenetic age estimators. We propose to test how pair bonding, disruption and biparental care, impact comparatively epigenetic aging in males and females, both the offspring as well as their parents. (c). we will explore the impact of CDK8/19 inhibition in epigenetic aging. Pharmacological interventions aiming to alleviate aging, besides providing avenues for the development of anti-aging therapies they also point to disparities impacting differentially the different sexes. Preliminary findings in mice indicate that inhibition of cyclin dependent kinases (CDK) 8/19, which regulate signal-induced transcription represents an avenue that may hold significant anti-aging value, preferentially towards females. Here we propose to explore if CDK8/19 inhibition decreases the epigenetic age, and alleviates telomere attrition and mitochondrial abundance of outbred deer mice. The proposed study constitutes a first effort to describe sex-based disparities in epigenetic aging in relation socioenvironmental factors and choices that impact the women’s social environment in the context of pair bonding and parents’ genetic relatedness. A. pharmacological intervention that prevents agent preferably in women will also be evaluated.

NIH Research Projects · FY 2025 · 2001-09

The South Carolina IDeA Networks of Biomedical Research Excellence (SC INBRE) is a state-wide network whose goals are to enhance and strengthen the biomedical research culture and infrastructure at network institutions while increasing access to undergraduate research training opportunities for students across the state, creating a pipeline to build the future biomedical research workforce. During the current funding cycle of SC INBRE IV, over 900 students were trained in biomedical research labs throughout the SC INBRE network. SC INBRE faculty and students produced over 200 publications and gave 760 presentations during this funding cycle while network PUIs acquired over $9 million dollars in extramural funding from a variety of federal and non-federal sources. We will build upon these successes in SC INBRE V. The network’s reach across the state will expand to sixteen institutions, three Comprehensive Research Universities and thirteen Primarily Undergraduate Institutions (PUIs), including two new PUIs, with long-time network members serving as role models for these new institutions. The Administrative Core, in addition to providing fiscal and administrative support, will organize a variety of career and professional development activities for faculty and students, including opportunities to network and develop collaborations with SC INBRE colleagues. Expanding upon our previous bioinformatics focus, in SC INBRE V our new Data Science Core will provide workshops and hands-on training opportunities for faculty and students seeking to analyze big data in multiple types of biomedical research projects. The Developmental Research Project Program, through Research Project and Pilot Project grants, will support early-career faculty seeking to establish and grow their research programs or enable investigators to collect critical data to advance current biomedical projects while enhancing competitiveness for further funding. SC INBRE will continue to promote undergraduate research training at network PUIs through the Student Research Program as well as providing a unique opportunity for students to develop a mentored-research project through the Student-initiated Research Project grant. To further expand its impact on student training, SC INBRE will also provide research opportunities for students attending South Carolina institutions outside of the network, maximizing the impact SC INBRE can have on student training. The proposed alterations and renovations at four PUIs will expand research opportunities at those institutions by increasing biomedical research capacity through additional research space or installation of critical fixed equipment. Through the program proposed, SC INBRE V will continue to have a profound impact on biomedical research at institutions across South Carolina.