Awardees

Human T-cell leukemia virus type-1 (HTLV-1) is an oncogenic human retrovirus affecting over 20 million people worldwide. HTLV-1 infection can cause adult T-cell lymphoma (ATL) and other serious inflammatory diseases. Estimates report that 5-10% of HTLV-1 infected patients will develop a serious condition such as ATL, which has poor 4-year survival and high relapse rates. HTLV-1 has persistent infection rates across the globe and reaches up to 45% prevalence in certain communities. Despite this impact on human health, there are no direct-acting antivirals (DAAs) or vaccines against HTLV-1. HIV-1 and HTLV-1 are from the same viral family and encode for a homodimeric aspartyl protease crucial for cleavage of functional proteins from viral polyproteins. The activity of HIV-1 and HTLV-1 protease is essential to their viral life cycles. The Schiffer laboratory has extensive experience with viral protease crystallography and inhibition, especially with viral proteases for HIV-1, HCV NS3/4A, and SARS-CoV-2 main protease. This expertise uniquely positions me to design, synthesize, and characterize potent, resistance-thwarting protease inhibitors against HTLV-1 protease. Resistance-preventing DAA design is essential because of the selective pressure applied during DAA treatment. An ideal and proven strategy for developing a highly potent and resistance-preventing viral protease inhibitor is to target the active site through rational design using the substrate envelope. The substrate envelope for HTLV-1 protease has not been characterized and we lack a detailed understanding of the protease substrate specificity. I hypothesize that by translating strategies from our design of HIV-1 protease inhibitors, namely characterizing HTLV-1 protease’s substrate specificity, I can design potent and resistance-preventing DAAs for HTLV-1 protease. Aim 1: Characterize the structural basis for HTLV-1 protease substrate specificity. HTLV-1 protease cleaves six substrates by recognizing cleavage sites between individual proteins of the viral polyprotein. I will investigate the molecular basis of this recognition underlying protease specificity by determining cocrystal structures of the protease with bound substrates. The conserved volume inhabited by the substrates will define the substrate envelope and inform inhibitor design for HTLV-1 protease. Aim 2: Rationally design, synthesize, and characterize inhibitors of HTLV-1 protease to optimize potency. HIV-1 and HTLV-1 proteases share an active site amino acid sequence identity of 45% and high structural similarity. Therefore, I will begin inhibitor design by testing a selection of our in-house HIV-1 protease inhibitors, which have already shown low (1 µM) to moderate (30 nM) potency against HTLV-1 protease. I will combine experimental inhibition assays with cocrystal structure analysis to identify lead compounds for inhibitor design. I will leverage substrate specificity of the protease by moving inhibitor design towards compounds that mimic the shape of substrates, leveraging the substrate envelope (Aim 1), and the interactions between protease and substrate. I aim to produce novel, highly potent (sub-nM) inhibitors that will be promising DAAs for further investigation against HTLV-1.

Huntington’s Disease – a devastating neurodegenerative condition – is caused by a defect in the Huntingtin gene, resulting in the production of alternative forms of Huntingtin mRNA and protein. This proposal will use small RNA drugs to reduce alternative forms of Huntingtin in mouse models of Huntington’s disease and determine the effect on disease features and outcomes. Findings from these studies will provide insight into the mechanisms underlying Huntington’s Disease to inform the development of future therapeutics.

Mitochondria are essential for cell health and survival. Understanding the quality control machinery that mitochondria employ to maintain a healthy network is critical for health and disease. Our lab recently showed the role that lipid transfer protein Vps13D plays a critical role in mitochondrial clearance by autophagy (mitophagy) in the Drosophila developing midgut. Vps13D has been implicated in human movement disorders, highlighting the importance of understanding how it controls this process. Importantly, we do not know what proteins Vps13D may be interacting with at the mitochondrial surface to facilitate mitophagy. I performed an RNAi screen against mitochondrial genes that were shown to physically interact with Vps13D in human cells. I discovered that Mtch, the fly homolog of MTCH2, phenocopies both mitochondrial and autophagic defects that Vps13D mutants display, including failure to clear mitochondria, autophagic cargoes like p62, and the autophagy protein Atg8a. I generated a null mutant for Mtch, which displays phenotypes similar to what is observed by Mtch knockdown with RNAi and Vps13D mutants. Importantly, Mtch mutant cells exhibit a robust decrease in Vps13D protein puncta. I plan to use this Mtch mutant to: (1) characterize the function of Mtch in mitophagy, (2) determine the relationship between Mtch and Vps13D in mitophagy, and (3) investigate the relationship between Mtch and known regulators of autophagy and mitophagy. These studies will advance the field by creating a better understanding of mitophagy, and will also provide a novel genetic pathway to study that could lead to targeted therapies to correct mitochondrial disorders.

RNAi-based drugs are emerging as a new class of therapeutic modalities that are transforming pharmaceutical development. The National Institute of Arthritis and Musculoskeletal and Skin Diseases has granted a K99/R00 Pathway to Independence Award to Dr. Qi Tang to support his career transition to an independent principal investigator position at a U.S. academic institution and to fund his research on developing a programmable siRNA-based therapeutic platform for gene silencing in the skin. Dr. Tang will receive integrated scientific and career training during his K99 phase at UMass Chan, and in R00 phase, he will work to establish his independent laboratory with a focus on designing and expanding the utility of siRNA therapeutics for treating inflammatory skin diseases that currently lack sufficient treatments or are undruggable by conventional modalities.

Down syndrome (DS) is caused by trisomy for human chromosome 21 and affects more than five million individuals worldwide. Autism spectrum disorder (ASD) is a common co-occurring condition in persons with DS. Because individuals with DS-ASD often present with deleterious behaviours, such as self-injurious behaviour, aggression, sleep disturbances, and feeding difficulties, identifying effective treatments for the behavioural sequelae of DS-ASD has the potential to improve quality of life for individuals with DS and their caregivers. However, recent research has focused on diagnosing DS-ASD and describing its behavioural profile. The underlying molecular mechanisms that contribute to DS-ASD risk remain unexplored. Other DS-associated phenotypes likely result from dysregulation of the Sonic hedgehog (Shh) signalling pathway, which is a critical developmental pathway. Because Shh signalling is required for the differentiation of serotonergic neurons and because the serotonergic system is implicated in the pathogenesis of ASD, we hypothesized that disruption of Shh could result in behavioural phenotypes relevant to ASD. To address this hypothesis, we will perturb Shh signalling in developing zebrafish and assess serotonergic neuron morphology, overall brain structure, brain activity, and behaviour. How trisomy 21 contributes to misregulation of Shh also merits further study. Based on a previous screen of chromosome 21 genes, we selected HMGN1 as a likely regulator of Shh. We will overexpress HMGN1 and explore its effects on Shh signalling, serotonergic neurons, behaviour, gene expression, and epigenetic modifications. Successful completion of this project will lay the foundation for drug screens relevant to DS-ASD and cognition in larval zebrafish models.

Negative affect and stress experienced during alcohol abstinence can be a major factor contributing to relapse in alcohol use disorder, yet underlying neurobiological mechanisms remain ill-defined. Corticotropin-releasing factor (CRF)-expressing neurons in the bed nuclei of the stria terminalis (BNST) are involved in anxiety and stress responses, and they play a major role in the withdrawal. A subcommissural population of CRF neurons in the BNST (vBNSTCRF) is heavily innervated by hindbrain noradrenergic neurons that co-express prolactin releasing peptide (PrRP). Because these PrRP neurons are sensitive to both stress and interoceptive state, they are likely involved in the development of stress hypersensitivity following withdrawal. However, the role of PrRP neurons in alcohol-related behaviors has not been studied. I hypothesize that signaling of PrRP neurons to vBNST during acute ethanol withdrawal contributes to the development of negative affective behaviors, and that ethanol withdrawal potentiates vBNSTCRF responses to stress and PrRP neuronal activation. In the proposed project, mice will undergo chemogenetic silencing of PrRP+ neurons projecting to vBNST during acute ethanol withdrawal to examine the necessity of the circuit in the development of negative affective behaviors (Aim 1). Then, the influence of ethanol withdrawal on in vivo calcium responses of vBNSTCRF neurons to stress and chemogenetic activation of PrRP+ neurons will be explored using fiber photometry (Aim 2). Finally, monosynaptic tracing and whole brain imaging will be used to define additional brain regions innervating vBNSTCRF neurons that may be modulated concomitantly during ethanol withdrawal (Aim 3). The results of these studies will provide an improved understanding of neurobiological mechanisms impacting affective behavioral changes during ethanol abstinence. This project also provides a strong platform to expand and strengthen the trainee’s expertise in modern behavioral neuroscience approaches, including intersectional viral strategies for chemogenetic manipulation of neural circuits, observation of cell-type specific in vivo calcium signaling, and characterization of monosynaptic inputs to specific cell populations.

Regulation of innate immunological self-tolerance, or the ability of cells to discern “self” from “non-self” has long been studied in the periphery in autoimmune disorders, especially in the context of nucleic acids (NA). Understanding of self-tolerance in the central nervous system (CNS), however, has not been thoroughly investigated despite expression of these NA-sensing TLRs by microglia, the primary phagocyte of the CNS. Published data from our lab highlights that microglia retain untranslated RNA transcripts from engulfed myelin for days after phagocytosis in vitro and in human multiple sclerosis patients. Based on these data, I hypothesized that these retained transcripts could aberrantly activate endosomal TLRs. I, thus, induced primary demyelination in UNC93B1 -/- mice, which lack functional NA-sensing TLRs, and observed that these mice remyelinate more efficiently than wildtype. These data suggest that signaling of NA-sensing TLRs suppresses remyelination during demyelinating disease. Several exciting questions have now arisen, which I will tackle in this proposal: 1) Is myelin phagocytosis causing aberrant endosomal TLR signaling? 2) Are microglia the primary cell type driving this response? 3) Does a specific NA-sensing TLR hinder remyelination? I hypothesize that TLR7 is aberrantly signaling in response to engulfed myelin RNAs in microglia and suppressing remyelination. To address these questions, I have acquired powerful in vivo molecular genetic tools to manipulate UNC93B1 and endosomal TLR function. I will first identify molecular pathways that are changed in microglia in vitro in response to chronic myelin phagocytosis and test whether these molecules are UNC93B1-dependent (Aim 1a). I will then determine if the UNC93B1 dependent effects that I observed on remyelination are microglia-specific (Aim 1b). Lastly, I will identify the endosomal TLR underlying these UNC93B1 effects (Aim 2). I am now in a strong position to molecularly dissect the role of NA sensing TLRs in remyelination during demyelinating disease, which has high long-term therapeutic potential.

B cells are essential immune cells that protect the host from infections via antibody production. This requires B cells to acquire e9ector functions and di9erentiate from naïve into germinal centers, and eventually into antibody-secreting plasma cells. Cell- cell interactions underpinning e9ective B cell response have been extensively studied, yet, less focus has been placed on soluble factors involved in this process, notably, mechanistic insights into lipid production and sensing on B cell immunity is still lacking. To this end, I will characterize the role of the liver X-receptors (LXR), nuclear hormone receptors regulating cholesterol homeostasis, during a B cell response. I aim to understand, with the highest granularity, how B cells integrate intrinsic and extrinsic lipid metabolic cues. Using cutting edge approaches, including conditional and inducible murine knock-out models, dietary interventions, targeted epigenetic profiling, single-cell RNA sequencing (ScRNAseq), and spatial transcriptomic to 1) Investigate LXR requirements for germinal center B cell and plasma cell di9erentiation, proliferation and maintenance in both homeostasis, vaccination and infection, in di9erent tissues; 2) Elucidate the molecular mechanisms of LXR transcriptional activity and regulation in germinal centers and antibody-secreting plasma cells; and 3) Identify the natural LXR ligand(s) that specifically shape B cell responses. My research will help resolve with high granularity how lipid metabolite sensing tunes humoral immunity in steady state and inflammation. Furthermore, it will help better understand B cell immuno-metabolic circuits that are tuned by lipid metabolites and that might be leveraged to design harmacological interventions enhancing antibody-mediated immunity.

While there are many FDA-approved therapies to treat relapsing-remitting multiple Sclerosis (MS), there are far less options for treating neurodegeneration in progressive disease. Intriguingly, similar to other neurodegenerative diseases (e.g. Alzheimer’s disease and frontotemporal dementia), a hallmark feature of progressive disease in MS is the loss of synapses and gray matter atrophy. Our lab recently discovered a striking loss of synapses in the visual thalamus of MS patient tissue and MS-relevant mouse and marmoset models concomitant with visual impairment. This was particularly intriguing since prolonged visual impairment is historically attributed to demyelination of the optic nerve and is a frequent occurrence in MS patients. As complement proteins were previously shown to mediate synapse elimination by phagocytic microglia in neurodegenerative disease and genetic variants in complement proteins have recently been correlated with visual impairment in MS patients, Dr. Schafer’s lab has been exploring this pathway in synapse loss in the visual thalamus in MS. First, Dr. Schafer’s lab showed that complement proteins C1q and C3 were both increased in a mouse and non-human primate model of MS (experimental autoimmune encephalomyelitis, EAE). However, unlike in development, C1q did not localize to synapses in this context. Instead, C3 was highly synaptic in EAE to induce microglia-mediated phagocytosis and elimination of synaptic material. In contrast to C3 at synapses, Dr. Reich and Dr. Schafer identified that C1q was particularly high in microglia surrounding chronic active MS lesions and loss of C1q in microglia in the mouse EAE model attenuated the inflammatory response of microglia. Still, it is unclear how C1q is modulating inflammation, and whether C1q is working upstream of C3 to regulate synapse loss or if synapse loss is occurring through the alternative pathway, independent of C1q. Also, there are many other molecules that regulate complement proteins and it is unclear how many of these complement-related proteins contribute to MS-related disease. Therefore, the overall goal of this proposal is to gain a more comprehensive understanding of how complement proteins are regulated in demyelinating disease.

Opioid overdose deaths and other substance-related mortality remain at an all-time high in the United States, and evidence suggests that mortality will continue to worsen without significant changes to the landscape of opioid use disorder (OUD) treatment. Overdose mortality is the leading cause of death in the first two weeks post-release due to a variety of factors including changes in drug tolerance during incarceration and volatility of the illicit drug supply, leading to a more than 100-fold increased risk of overdose death compared to the nonincarcerated population during this period. Despite advances in addiction health services and clinical addiction medicine, many people with OUD do not have access to healthcare or medications for opioid use disorder (MOUD) treatment, which remain the most effective treatment strategies to reduce OUD- related mortality. Correctional facilities such as jails are a critical healthcare access point for people with OUD who may not receive healthcare in other settings. However, MOUD treatment availability in jails is highly variable across the United States, leaving many people with OUD without access to evidence-based treatment while incarcerated. Implementation of MOUD treatment in jails is critical to improve accessibility of MOUD treatment and reduce OUD-related mortality in this vulnerable population. There is need for further research elucidating strategies that lead to successful and sustained implementation of MOUD in jails and other correctional settings. This proposal uses a mixed-methods approach to analyze implementation of MOUD from multiple perspectives. The proposal utilizes data from the Massachusetts Justice Community Opioid Innovation Network (MassJCOIN) study, a type 1 hybrid effectiveness-implementation study of MA Chapter 208, which established a pilot program to expand all FDA-approved forms of MOUD in MA county jails. Aim 1 will qualitatively assess organizational factors related to MOUD implementation in jails and post-release overdose risk through thematic analysis of interviews with jail staff and people who received MOUD while incarcerated in MA jails. Aim 2 will investigate the association between staff perspectives of MOUD and organizational factors such as staff training and readiness for change. Aim 3 will compare MOUD retention outcomes for people who screened positive for OUD while incarcerated between different types of MOUD treatment using the Public Health Data (PHD) Warehouse database created by the Massachusetts Department of Public Health. The proposed research and training plan will provide rigorous education in addiction health services research, which will be integrated with the robust clinical training of UMass Chan Medical School and supported through a multidisciplinary team of mentors with significant expertise in implementation science and OUD research in criminal-legal settings. This proposal will provide valuable insights into strategies that lead to effective and sustained MOUD treatment in jail settings with the goal of increasing accessibility to evidence-based MOUD treatment and reducing opioid-related mortality for people who experience incarceration.