Biological and Health Sciences

Nicholas Boulis, MD

Professor, School of Medicine, Neurosurgery

Facial Re-innervation in a Porcine Facial Paralysis Model

Amyotrophic lateral sclerosis (ALS) is a disease that causes the death of cells known as motor neurons. These cells play a critical role in relaying signals from the brain to the muscles. Their death leads to a disease characterized by a progressive paralysis that ends with complete loss of motor function. ALS patients die from respiratory failure once paralysis reaches the muscles that allow them to breathe. Currently, treatment options for this disorder a severely limited. Restoring some lost motor function, particularly to the respiratory muscles, would provide ALS patients with a significant improvement in their quality of life. Previous research has shown that motor neurons can be engineered to become active in response to light. This allows for the cells to be turned on and off by controlling a light source close to them. When implanted into a nerve in a mouse, these motor neurons can extend axons that connect to muscles. When light is applied to these cells, the associated muscles contract. To treat ALS patients, these motor neurons will have to project axons over greater distances and be protected from immune rejection. Therefore, we seek to extend this technology to the pig, which is more similar in size and immunology to ALS patients. We will show that these types of motor neurons can survive within pig nerves and reinnervate their associated muscles. This study will serve as the first step in developing a system that can control the muscles required for breathing.

Michael Dattilo, MD, PhD

Assistant Professor, School of Medicine, Ophthalmology

Physiology of Spontaneous Retinal Venous Pulsations

Measurement of intracranial pressure (ICP) is necessary for the diagnosis and management of certain vision-threatening and life-threatening ocular and neurologic diseases. However, all current methods to assess ICP are invasive and are associated with side effects, such as headaches, cerebrospinal fluid (CSF) leaks, infection, and brainstem herniation. Spontaneous retinal venous pulsations (SRVPs) are present in ~90% of normal people and are affected by the translaminar pressure difference (TLPD), the difference between intraocular pressure (IOP) and ICP. I propose to advance our understanding of the relationship between SRVPs, IOP, and ICP in a clinically relevant animal model of normal physiology and to utilize this relationship to determine if SRVPs can be used to develop algorithms to predict ICP. If SRVPs can be used to predict ICP, I will use the algorithms developed in this grant application as the basis for the development of a portable, hand-held, and accurate non-invasive system to determine ICP.

Christine Dunham, PhD

Associate Professor, School of Medicine, Biochemistry

Mechanism of MazF-mt9 mediated ribosome stalling

The increasing global spread of antibiotic resistance among pathogenic bacteria threatens a post-antibiotic era in human healthcare. Detailed studies of resistance mechanisms and identification of new antimicrobial targets are therefore urgently required. New antimicrobial targets present in pathogenic bacteria are emerging as a potentially powerful approach to tackling increasingly resistant and persistent bacteria. Attractive pathways include those that promote bacterial survival during stress conditions allowing bacteria to either tolerate such environments or for a subset of a given bacterial population to survive (“persister” cells). The recent identification that the bacterial stringent response and, specifically, toxin-antitoxin gene modules promote bacterial antibiotic persistence has placed an urgency on understanding the underlying molecular mechanisms of their action and regulation. This proposal builds on exciting new results by collaborators that demonstrate that the Mycobacterium tuberculosis toxin MazF-mt9 inhibits cell growth by causing ribosome stalling (Barth et al., Nat Comm 2019). All cellular ribosomes stall during protein synthesis and all organisms contain mechanisms to prevent and, as such, rescue stalled ribosomes. The functional consequences of MazF-mt9 mediated ribosome stalling is unknown and this project proposes experiments aimed at collecting essential preliminary data to submit a grant application to a federal agency.

Judith L. Fridovich-Keil, PhD

Professor, School of Medicine, Human Genetics

Gene replacement in a GALT-null rat model of classic galactosemia

Classic galactosemia (CG) is a rare genetic disorder that results from loss of galactose-1-P uridylyltransferase (GALT). People born with CG face dramatically increased risks for long-term complications including cognitive, motor, and other disabilities despite early detection by newborn screening and immediate and lifelong dietary restriction of galactose, which is the current standard of care. The mechanisms underlying long-term complications in CG remain unclear and may differ by tissue; there is currently no known intervention that prevents them. Recently, we reported the development and initial characterization of a GALT-null rat model for CG. Our rats show both appropriate biochemical markers and also cognitive, motor, and other long-term deficits reminiscent of patient outcomes. Here, we propose a pilot study using our rats in a pre-clinical test of gene therapy for CG. Specifically, we propose to conduct a dose-response experiment to determine how much GALT activity must be restored, and in which tissues, to prevent the abnormal accumulation of galactose metabolites thought to underlie complications. We also propose a small longitudinal study to determine whether a single neonatal administration will suffice, or whether booster injections are required. The results of this pilot will establish a foundation for future studies to test whether GALT gene replacement is sufficient to rescue cognitive, motor, and other long-term deficits in GALT-null rats.

Peijian He, PhD

Assistant Professor, School of Medicine, Dept. of Medicine

Crosstalk between Iron Metabolism and Diabetes

Body iron in excess is strong risk factor for diabetes and worsens diabetic complications. Reciprocally, diabetes further promotes systemic iron accumulation. Thus, iron metabolism and diabetes inter-regulate in a vicious cycle. A better understanding the scientific mechanisms of the crosstalk could lead to the development of potential novel treatment modalities for diabetic control. Hyperactivated protein kinase C (PKC) is a key signaling change in diabetes. Our novel preliminary findings suggest PKCα stimulates dietary iron absorption largely through the activation of intestinal ferroportin (Fpn), the only iron exporter. The importance of PKCα in dietary iron absorption is further supported by findings in PKCα-/- mice, which display decreased Fpn expression and increased iron retention in intestinal epithelium as well as diminished systemic iron content. Additional data show that diabetes-induced iron loading exacerbates liver injury and inflammation by increasing ferroptotic cell death of the hepatocytes, a novel mechanism which has not previously been identified in liver injury development. We hypothesize that hyperactive PKCα signaling is a critical for hyperglycemia-induced iron loading and, as a consequence, exacerbated liver injury. We will utilize genetically engineered mouse models, cultured intestinal epithelial cells, and intestinal biopsies of diabetic patients to test our hypothesis. In Specific Aim we will uncover the mechanism by which hyperactive PKCα up-regulates Fpn expression and iron export in the intestine, and in Specific Aim 2 we will identify the mechanism by which excess iron exacerbates liver injury in the context of hyperglycemia.

Marina Sorrentino Hernandes, PhD 

Assistant Professor, School of Medicine, Dept. of Medicine

Poldip2 as a novel regulator of brain endothelial cell permeability and blood brain barrier integrity in cerebral ischemia

Cerebral ischemia, commonly called stroke, is the leading cause of disability in the USA and is frequently accompanied by disruption of the blood-brain barrier (BBB), which forms the interface between the vasculature and the brain. Following cerebral ischemia, the barrier integrity of brain microvascular endothelial cells that surround blood vessels is compromised, leading to a subsequent increase in leakiness of the BBB. This increase in permeability leads to the development of brain edema or swelling, which has been associated with higher mortality and longer hospitalization among stroke survivors. Understanding how endothelial cell barrier function integrity can be maintained is important to be able to develop new drugs to improve stroke outcome. Our research focuses on further understanding the mechanisms involved in endothelial cell permeability and BBB disruption, with a goal towards developing new therapies.

Stroke remains one of the main causes of death and disability worldwide. The current therapy for cerebral ischemia is very limited and the administration of the only FDA approved drug for the treatment of stroke also increases the permeability of the BBB, possibly leading to bleeding in the brain, thus, a detailed understanding of the processes involved in the BBB permeability is critical. Completion of these aims will result in a deeper understanding of how different signaling pathways in brain microvascular endothelial cells contribute to disruption of the BBB in stroke. We hope that by understanding these processes we will be able to efficiently control them by engineering new targeted therapeutics.

Dorothy A. Lerit, PhD

Assistant Professor, School of Medicine, Cell Biology

Regulation of centrosome mRNAs by FMRP

Fragile X Syndrome (FXS) is the most common heritable cause of intellectual disability and autism. FXS arises from mutation of the FMR gene, which encodes an RNA-binding protein, FMRP, that functions as a translational repressor. Given the causal relationship to FXS, numerous studies have cataloged putative RNA substrates of FMRP. However, surprisingly few FMRP targets have been validated through follow-up studies. We recently discovered that Drosophila FMRP is a potent regulator of two conserved, centrosome-associated mRNAs. Centrosomes are microtubule-organizing centers tasked with diverse functions, including regulating cellular proliferation, intracellular transport, and ciliogenesis. How cells regulate centrosome activities to achieve such diversity of function is incompletely understood. Our FMRP data suggest that, at least in Drosophila models, post-transcriptional regulatory programs contribute to centrosome regulation. This proposal aims to extend these studies to mammalian models to test the hypothesis that FMRP mediates aspects of centrosomal mRNA regulation. FMRP target validation remains a prominent knowledge gap hindering our understanding of FXS pathophysiology and functional roles of FMRP. By utilizing creative and complementary approaches to probe RNA-protein interactions, we aim to understand fundamental mechanisms of centrosome regulation while shedding light on unappreciated functions of FMRP.

Bo Liang, PhD

Assistant Professor, School of Medicine, Biochemistry

Novel in vitro mini-nucleocapsid of respiratory syncytial virus

Non-segmented negative-sense (NNS) RNA viruses include many significant human pathogens, such as rabies, Ebola, and respiratory syncytial virus (RSV). Unfortunately, no effective vaccine or antiviral therapy is available to prevent or treat many of those pathogens. Despite the evident importance of RNA synthesis by NNS RNA viruses, an in-depth mechanistic understanding is lacking. A major barrier in the field is the lack of a tractable in vitro system in which purified polymerase acts on its protein-packaged RNA template nucleocapsid (NC). We propose herein to exploit my expertise to utilize RSV as a model system and overcome the critical barrier in the NNS field. The objective of this proposal is to provide a novel solution for mechanistic studies of the RSV RNA synthesis. We have successfully accomplished the first major step, that is to prepare the RNA-free N protein (N0) and reconstitute short N:RNA in vitro. The proposed project is outlined here: 1) We will reconstitute a functional mini-nucleocapsid (mini-NC) in vitro using the RNA polymerization assay. 2) We will use cryo-EM to reveal atomic-level structures of mini-NC and the architecture of polymerase bound to mini-NC that is unique and distinct from all eukaryotic systems. Upon successful completion, these data will provide novel insights on the N protein-packaged RNA template used by RSV and related NNS RNA viral pathogens, and will facilitate the rational design of novel antiviral drugs to treat the devastating diseases that these viruses cause.

Kenneth Myers, PhD

Instructor, School of Medicine, Cell Biology

Mechanisms of mRNA localization and local translation at synapses

Local mRNA translation is essential for axonal pathfinding and synaptic plasticity, both of which underlie the proper wiring and function of neural circuits. Likewise, dysregulated mRNA localization and translation is increasingly appreciated as one of the most common molecular pathologies of neurodevelopmental disorders, such as autism. Local translation provides a mechanism, especially in distal neuronal processes far from the cell body, for a neuron to regulate the proteome in response to local cues on rapid timescales. There are additional advantages, such as the energetically favorable nature of transporting a single mRNA that can produce multiple copies of a protein on-site, as opposed to transporting multiple proteins from the cell body to that site. However, while considerable progress has been made in our understanding of local translation neurons, the mechanisms underlying mRNA localization and anchoring at synapses currently remains unclear. This proposal aims to address this deficit, by studying a recently identified, novel ribonucleoprotein complex involved in the localized translation of mRNAs at synapses. The successful completion of this research will provide new insights into the regulation of the local proteome at synapses, which is critical for our understanding of learning and memory under normal and diseased conditions.

Gonzalo Vazquez Prokopec, PhD

Associate Professor, ECAS, Environmental Sciences

The ecology and transmission of lone star tick-associated emerging arbovirus in Georgia

Background: Ticks are the most important vectors of human and animal disease in the United States. Even though there is an extensive knowledge about tick-borne bacterial diseases (e.g.. Lyme borreliosis), knowledge about factors related to the emergence of tick-borne viral diseases is limited. In recent years, two new arboviruses, Heartland virus and Bourbon virus, were reported in the Midwest and Southern US, causing severe, often fatal human disease. The tick species implicated as primary vector (Amblyomma americanum) represents the most frequent human biting tick in the southern US. The presence of specific antibodies in wildlife demonstrates extensive exposure to the virus in this region.

Objective: We propose a longitudinal field study, sampling ticks during the entire season (May to October), to characterize the ecology and transmission of Heartland virus in nature. The study area was targeted in our preliminary studies as a transmission focus due to the evidence of viral exposure in white-tailed deer, and the proximity to the residence of the only human case of disease reported in GA. Our study has two aims: one focused on extensive field collections to identify the presence of arbovirus and characterizing the enzootic cycle in ticks, and a second aim quantifying the genetic diversity of detected viral isolates compared to isolates from other regions.

Impact: The limited knowledge about the ecological factors involved in the emergence and transmission of Heartland and Bourbon virus limits our ability to detect and respond promptly and adequately to events of human disease, and to estimate the public health burden of these fatal infections.

Daniel Reines, PhD

Professor, School of Medicine, Biochemistry

A test of the biological function of an inducible, ubiquitious cellular organelle: IMP dehydrogenase-based rods and rings

A new cellular organelle called Rods and Rings (RRs) has been described recently that is a micron-long reversible assembly of the enzyme IMP dehydrogenase (IMPDH). All cells examined have RRs which contain IMPDH at its core. The enzyme controls a key step in metabolism and is essential for embryonic development. These RR structures let IMPDH become resistant to feedback inhibition, thereby regulating its activity and allowing it to meet a high demand for GTP, the pathway’s final product and a key cellular building block. Rod and Ring formation is observed when cells proliferate or when IMPDH is inhibited by drugs that result in a lowered GTP pool.

While IMPDH and RRs are well studied, a cellular requirement for the assembly of the enzyme into this organelle has not been proven. This seed-proposal tests the biological significance of RR formation in lymphocytes which depend unusually heavily upon IMPDH for proliferation in response to antigen (like a transplanted organ). Immunosuppressant drug inhibition of IMPDH exploits this lymphocyte Achilles heel, while sparing other cells which make GTP by an alternative pathway. We will genetically engineer lymphocytes to have an IMPDH that cannot assemble into Rods and Rings while the enzyme remains otherwise catalytically intact. We will test activated lymphocytes bearing this ‘designer’ IMPDH for their ability to divide and secrete bioactive products. This will be the first demonstration of the role of RR formation in cell physiology and will enable the launching of a comprehensive project to thoroughly understand this newly recognized organelle.

Jennifer Spangle, PhD

Assistant Professor, School of Medicine, Radiation Oncology

Deciphering the function and impact of Histone H3 lysine conversions as oncohistones

Over 1.7 million individuals will be diagnosed with cancer and 600,000 cancer-associated deaths will occur in the US in 2020. Devoting resources to define mechanisms of oncogenicity and applying this knowledge to the development of therapeutic agents is required to combat cancer.

Among the mutations that cause cancer, many occur in genes that are expressed in all cells, but specific types of cancer occur. For example, Histone H3 is a protein that packages chromosomes into cell nuclei as chromatin to control gene expression. Mutations in Histone H3 are associated with an insidious brain cancer that occurs in children, pediatric glioma. Often these mutations cause a single amino acid change from lysine to another amino acid, which alters the function of the histone protein as well as gene expression. How these changes lead to cancer in specific cell types and alter histone function is unclear.

We have identified novel H3 changes, termed XtoK, in which mutation(s) introduce a new lysine residue in H3 in more than 30 patient tumors including breast cancer. These H3 XtoK mutations can transform cells, which is an early stage in cancer. However, the mechanism(s) by which XtoK histones are oncogenic is unclear. We hypothesize that H3 XtoK changes introduce structural changes that alter DNA packaging and/or expression, and/or create a new target for enzymes that modify chromatin, supporting a potentially druggable target. The proposed studies use a combination of human cells and budding yeast to model these changes and explore how they contribute to cancer.

PI: Amanda I. Gillespie, PhD

Assistant Professor, School of Medicine, Otolaryngology

co-PI: Eva Van Leer, PhD

Associate Professor, Communication Disorders, Georgia State University

GACTSA/URC Award

Optimization of Voice Therapy Adherence with Mobile App Support

The ultimate goal of our research is to determine the best methods to treat patients with voice disorders. Nearly 88 million people in the United States experience voice disorders in their lifetime, which disrupt a person’s ability to communicate, and are socially and professionally devastating. Most voice disorders are treated with weekly voice therapy sessions and extra-clinical home practice. However, like other behavioral interventions (i.e. physical therapy, weight loss), many patients fail to adhere to therapy, leading to high drop-out rates, relapse and suboptimal outcomes.

Both treatment content and the nature of home practice contribute to these problems. Generalization of target voice techniques to everyday conversation is the most difficult aspect of voice therapy, yet receives little to no time in traditional approaches. Patients also often forget to practice, or fail to accurately replicate the target technique during practice.

Our hypothesis is that including conversation training in voice therapy and adding extra-clinical practice support will address these challenges and decrease the significant burden of chronic voice disorders. We will evaluate the effects of an extra-clinical practice support mobile application on practice adherence and patient motivation for voice therapy practice in Conversation Training Therapy (CTT)- a treatment that uses only conversational speech as therapeutic stimuli- compared to no-app practice. We will also study how practice amount and quality influences the efficacy of CTT. 

The proposed crossover trial will generate relevant data for large-scale studies of voice therapy efficacy and adherence, improving outcomes for patients and informing future treatment strategies for chronic voice disorders.