INBRE 3 (2015-2020) introduced the Developmental Research Project (DRP) program that allows individual faculty at SC INBRE network institutions to submit competitive proposals for biomedical research. INBRE 4 (2020-2025) will continue this impactful program. Since 2015, 6 Furman faculty have received this award including three (Jason Rawlings, Alison Roark and Adi Dubash) that received three years of individual support (~$225,000 each). Linnea Freeman received this award in 2018 and will complete her third year of funding in the first year of INBRE 4 support. Sri Chandrasekaran received this award in 2019 and will complete her second year of funding in the first year of INBRE 4 support. A brief description of their research is shared below.
Effects of antioxidants and growth conditions on fluconazole resistance in Cryptococcus neoformans by Sri Chandrasekaran (2019,2020)
Cryptococcus neoformans is the leading cause of fungal meningitis in immunocompromised patients. Anti-cryptococcal therapy is unfortunately inadequate due to increased drug resistance. The anti-fungal drug fluconazole (FLU) inhibits fungal growth by affecting ergosterol biosynthesis. FLU also moderately increases Reactive Oxidative Species (ROS). Treatment with select antioxidants, including ascorbic acid (AA), retinoic acid (RA), PDTC, and glutathione (GSH) leads to lowering of ROS and in most cases promotes FLU resistance in C. neoformans. Sensitivity to FLU is also impacted by temperature and nutrient content by mechanisms that remain elusive. We hypothesize that external factors can regulate expression of genes involved in counteracting effects of FLU. The proposed studies will explain the role of antioxidants, temperature, and nutrients in regulating FLU resistance in C. neoformans. We will establish the effects of environmental factors on the C. neoformans transcriptional profile in the presence of FLU and characterize C. neoformans colonies that are resistant to FLU-mediated cell growth inhibition. We will test the impact of antioxidants, temperature and nutrients on the response to FLU by determining total ergosterol content of cells treated at various temperatures and in various media. These studies will contribute towards understanding of mechanisms and factors promoting drug resistance in C. neoformans.
Sex differences in short chain fatty acid production and lipid metabolism: the role of the gut microbiome by Dr. Linnea Freeman (2018, 2019, 2020)
Given the ever-increasing rates of obesity in our country and the numerous health issues associated with high fat diets and/or obesity, it is imperative to further understand high fat diet-related consequences and their mechanisms. For example, obesity is linked to a disruption in the balance between two predominant phyla found in the gut microbiome: increased Firmicutes and decreased Bacteroidetes. The gut microbiome includes a wide variety of microorganisms and their genetic material; many of these microorganisms are in a mutualistic relationship with the host, participating in metabolism. The gut microbiome is ever-changing: influenced by age, environment, diet, and health status. Gut microbiome-derived metabolites, such as short chain fatty acids (SCFAs) are also proposed to affect the neuroinflammatory response due to consumption of a high fat diet. Our preliminary data reveals a correlation between gut microbiome diversity and microglia morphology in a mouse model of obesity. Therefore, we propose SCFA production influences sex differences in microgliosis following consumption of a high fat diet. We further propose that sex differences in lipid metabolism play a role in sex differences in diet-induced obesity. SCFAs affect glucose, lipid, and cholesterol metabolism. Based on these observations, the overarching hypothesis of our current research is: sex differences in lipid metabolism are due to sex differences in gut microbiota. Given our preliminary data that reveals sex differences in weight gain, microgliosis, and gut bacteria genera abundances, we want to further investigate whether gut bacteria influence sex differences in SCFA production and lipid metabolism, which may further link with our findings related to microgliosis.
Desmopolakin Harnesses RHO GTPASE and 39 MAPK Signaling to Coordinate Cell Migration by Dr. Adi Dubash (2017, 2018, 2019)
The desmosome is a highly specialized cell-cell junctional complex responsible for strong mechanical adhesion between cells, a characteristic required for normal tissue structure and resistance to mechanical stress. In addition, a growing body of evidence suggests that desmosomal proteins control many other fundamental biological processes such as cell proliferation, differentiation and migration. Therefore, it is not surprising that expression of protein members of the desmosome complex are altered in many different types of cancer. Loss of desmosome-mediated adhesion has been linked to tumorigenic phenotypes such as increased proliferation and migratory ability. The current proposal will investigate the role played by the desmosomal protein Desmoplakin (DP) in coordinating cell migration. Our preliminary evidence indicates that loss of DP (via siRNA-mediated knockdown) results in an increase in motility of human skin cancer cells. We hypothesize that DP coordinates the migratory properties of cancer cells via regulation of the Rho GTPase and p38 MAPK signaling pathways, both of which have been shown to play important roles in this process. To investigate this, we propose to determine if levels of active Rho GTPases and p38 MAPK are elevated upon loss of DP, and determine if abrogation of these signaling pathways can rescue the elevated motility observed in DP-deficient cells. Analysis of the signaling pathways involved will be achieved by biochemical pulldowns, immunofluorescence, and western blots/quantitative PCR. In addition, we will further investigate the migratory characteristics of control and DP knockdown cells, such as changes in cytoskeletal protrusions, alterations in focal adhesion size and number, and differences in production of extracellular matrix. By identifying the mechanistic signaling links responsible for DP-mediated migration, this work will provide significant insight into the function of desmosomes in this fundamental cellular process. Additionally, this work has the potential to uncover novel therapeutic targets to regulate both normal biological processes requiring cell migration (such as wound healing), as well as abrogation of pathological outcomes (such as cancer metastasis and invasion).
Interspecific Communication Between Anemones and Their Agal Symbionts by Dr. Alison Roark (2016, 2017, 2018)
Cnidarians are evolutionarily ancient animals including jellyfish, anemones, and corals, many of which form symbioses with intracellular, photosynthetic algae in the genus Symbiodinium. The goal of the proposed project is to determine the extent to which and the mechanism by which algal symbionts regulate development and reproduction of their cnidarian hosts. My hypothesis is that algal symbionts produce compounds that directly modulate host performance. Given their evolutionarily ancient origins, simple body plans, well established life histories, and mutualistic interactions with photosymbionts, cnidarians are particularly appropriate models for studying the impacts of interspecific cell signaling processes. In particular, studying the effects of exogenous compounds on reproductive function of anthozoans can provide information about conserved signaling pathways that are relevant to all animals. Phytochemicals such as flavonoids are increasingly recognized as endocrine-active compounds that influence reproductive capacity of animals including humans. My proposed work using the sea anemone Aiptasia pallidathus provides insight into the effects of plant-derived compounds on reproductive performance and the mechanisms underlying these effects in all animals, not just cnidarians.
Mechanisms of Chromatin Decondensation in Lymphocytes by Dr. Jason Rawlings (2015, 2016, 2017)
Control of T cell proliferation is essential to proper immune function; lack of proper control can lead to pathologies such as autoimmunity, immunodeficiency, and cancer. STAT5 is a transcription factor that is absolutely essential for peripheral T cell proliferation. Following T cell receptor (TCR) engagement, activated T cells produce IL-2 which induces proliferation via STAT5. Naïve T cells, for which TCR engagement has not occurred, are refractory to IL-2 stimulation, remaining quiescent during an immune response. This ensures a clonal expansion of antigen specific T cells. Recently, we demonstrated that IL-2 induces STAT5 activation and nuclear localization in naïve T cells; however, STAT5 cannot engage DNA due to the condensed nature of chromatin in these cells. This condensation is not due to global modification of histones as previously thought, but to a higher-order chromatin condensation that is dependent on the activity of the condensin II complex. In this proposal we will determine the signaling pathway(s) downstream of the TCR that are responsible for chromatin decondensation during T cell activation. We will also determine if chromatin condensation is a conserved mechanism to regulate proliferation in other lymphocyte populations. These studies will provide important insight into the epigenetic control of lymphocyte proliferation and function.