Pharmacology & Toxicology Department Theses and Dissertations
Permanent URI for this collection
About the programs
The advanced degree programs at the Indiana University of Medicine Department of Pharmacology and Toxicology prepare scientists for careers across the spectrum of biomedical research. The Master of Science (M.S.) degree is a thesis research degree that gives a student the intellectual background to understand and participate in ongoing research projects. The Doctor of Philosophy (Ph.D.) degree is offered for the student who wants to pursue an independent career in research. Students with the Ph.D. degree are prepared for an academic career combining research with teaching or for a career in industrial pharmaceutical research. A combined M.D./Ph.D. degree is open to qualified individuals who ultimately seek to direct biomedical research with a clinical emphasis.
For more information visit http://medicine.iu.edu/body.cfm?id=4418&oTopID=4418
Browse
Recent Submissions
Item Understanding the Structure-Function Relationship of Peptidergic Sensory Nerves in the Prostate(2024-12) Xia, Hanyu; Jerde, Travis J.; Fehrenbacher, Jill C.; Yeh, Elizabeth S.; Fishel, Melissa L.; Pierchala, Brian A.The prostate, like many other organs, is densely innervated. However, studies to date have largely focused on sympathetic and parasympathetic nerves with little attention given to the presence or function of sensory nerves in the prostate. Recent studies have suggested that the physiological function of sensory innervation extends beyond the detection of noxious stimuli, as anterograde release of neuropeptides from sensory nerves can affect vascular tone and local immune responses. Still, the broader role of peptidergic sensory innervation of the prostate remains unknown, and the research described herein fills this void in current prostate knowledge. Utilizing state-of-the-art tissue clearing and 3D immunofluorescence imaging, this study provides unprecedented visualizations of prostatic innervation, revealing an extensive network of peptidergic sensory nerves throughout the mouse prostate. Sensory nerves were observed in abundance accompanying vasculature and as independent nerve fibers wrapped around prostatic acini in a net-like fashion. To investigate the functional significance of this newly revealed sensory network, an intersectional genetic approach was employed to ablate peptidergic sensory nerves systemically. We found that Calca haploinsufficiency, the genotype control for the ablation model, diminished proliferating cells as determined by K-i67 positivity in the stromal compartment of the dorsal lobe and trended to decrease proliferation in other lobes. These findings suggest that sensory neurons might have developmental or homeostatic effects within the prostate. This work establishes a new foundation for understanding the complex roles of sensory innervation in normal prostate function and in prostatic diseases. Further studies are warranted to assess the role of sensory neurons and their neuropeptides on prostatic development and on proliferation in the presence of pro-inflammatory stimuli such as bacterial infection or tumor cells, which could lead to innovative approaches in prostate health management.Item Elucidating the Role of the Essential Kinase TgGSK in the Human Parasite Toxoplasma Gondii(2025-02) Krueger, Amanda; Yeh, Elizabeth; Arrizabalaga, Gustavo; Sullivan, William; Nass, Richard; Aoki, ScottToxoplasma gondii is an intracellular parasite that infects nearly a third of the world’s human population. While infection is largely asymptomatic in an immunocompetent host, Toxoplasma infection in immunocompromised or immunosuppressed individuals can lead to toxoplasmosis, which can include brain lesions and lead to death. Similarly, toxoplasmosis can result in birth defects, brain swelling, and blindness of a developing fetus in the case of a congenital infection. With minimal treatments for toxoplasmosis available, it is crucial to study parasite-specific processes that could be potential drug targets for the treatment of toxoplasmosis. Toxoplasma gondii divides through a unique process known as endodyogeny, where two daughter parasites are formed within a mother. In this study, we investigated a novel protein called TgGSK that is crucial for proper parasite division. Experiments reveal that TgGSK changes its localization within the parasite dependent on the stage of division. Knockdown of TgGSK causes abnormal division phenotypes and causes Toxoplasma to be unable to complete its propagation cycle. We determined through microscopy and phosphoproteomics that TgGSK may play its role in parasite division through an interaction with the centrosome, an organelle which is a main feature of cell division in many organisms. Our findings suggest that TgGSK also regulates messenger RNA processing. Finally, our study suggests that TgGSK is regulated and stabilized through acetylation from the GCN5b lysine acetyltransferase complex. Taken together, we have performed an in-depth study of the functional role of the essential protein TgGSK in Toxoplasma gondii. This and future studies have potential to demonstrate that TgGSK is a parasite-specific drug target for the therapeutic treatment of toxoplasmosis.Item Identification of a Hypothalamic Neural System That Can Reduce Body Weight and Adipose Mass in Diet-Induced Obesity(2024-11) Basu, Rashmita; Flak, Jonathan N.; Linnemann, Amelia K.; Witczak, Carol A.; Sheets, Patrick L.; Jerde, Travis J.Dynamic hypothalamic circuits balance energy intake with expenditure to protect individuals from obesity. Lasting negative energy balance, however, triggers a compensatory decrease in energy expenditure, hindering progressive weight loss. While we understand some key players underlying energy balance, the detailed neural underpinnings remain unclear. Here I will delineate the functional efferent circuitry from the ventromedial hypothalamic nucleus (VMN) that facilitates weight loss and prevents rebound weight gain. VMN neurons have long been linked to a role in energy balance. Both vesicular communication by VMN steroidogenic factor 1 (SF1) neurons and pituitary adenylate cyclase activating peptide (PACAP) release from VMN neurons are essential for maintaining body weight and activating VMNSf1 neurons curbs diet-induced obesity without altering food intake. However, the exact pathway of this VMN signal is unclear because the VMN does not directly communicate with preganglionic sympathetic neurons, indicating signal transmission through an efferent node. Of the few brain sites they communicate with, VMNSf1 neurons sends the densest projections to the caudal preoptic area (POA) and the anterior bed nucleus of stria terminalis (BNST). Stimulating VMNPACAP axonal fibers in the caudal POA, but not anterior BNST, induced thermogenesis in brown and beige adipose tissues in both sexes of mice. To identify caudal POA populations in body weight regulation, I activated excitatory (glutamatergic) and inhibitory (GABAergic) caudal POA cells in diet-induced obese male mice and found that both glutamatergic and GABAergic caudal POA neurons can reduce diet-induced obesity through separate means. While there is intra-POA communication, my data supports efferent communication with separate downstream circuits by glutamate and GABA caudal POA cells in ameliorating diet-induced obesity. Because the POA and BNST are extremely complex regions with diverse functions, I then employed deep transfer learning to pinpoint obesity and diabetes risk-associated cell subsets in the POA and BNST. Using single nuclei RNA sequencing on >200,000 nuclei from both sexes of mice, I identified 6 specialized sets of caudal POA and BNST neuronal subtypes that increased in obese and glucose-intolerant mice on a high-fat diet. Targeting these newly identified pathways and neuron subtypes could lead to future obesity and diabetes therapeutics.Item The Impact of Abstinence from Chronic Alcohol Consumption on the Mouse Striatal Proteome: Sex and Subregion-Specific Differences(2024-10) Duffus, Brittnie-lee Marie; Atwood, Brady; Oblak, Adrian; Mao, Yao-Ying; Baucum, AJ; Fischer, KathrynAlcohol misuse is the third leading preventable cause of death in the world. The World Health Organization currently estimates that 1 in 20 deaths are directly alcohol related. One of the ways in which consuming excessive levels of alcohol can both directly and indirectly affect human mortality and morbidity, is through chronic inflammation. Recently, studies have suggested a link between increased alcohol use and the incidence of neuroinflammatory-related diseases. However, the mechanism in which alcohol potentially influences neuroinflammatory processes is still being uncovered. We implemented an unbiased proteomics exploration of alcohol-induced changes in the striatum, with a specific emphasis on proteins related to inflammation. The striatum is a brain region that is critically involved with the progression of alcohol use disorder. Using mass spectrometry following voluntary alcohol self-administration in mice, we show that distinct protein abundances and signaling pathways in different subregions of the striatum are disrupted by chronic exposure to alcohol compared to water drinking control mice. Further, in mice that were allowed to experience abstinence from alcohol compared to mice that were non-abstinent, the overall proteome and signaling pathways showed additional differences, suggesting that the responses evoked by chronic alcohol exposure are dependent on alcohol use history. To our surprise we did not find that chronic alcohol drinking or abstinence altered protein abundance or pathways associated with inflammation, but rather affected proteins and pathways associated with neurodegeneration and metabolic, cellular organization, protein translation, and molecular transport processes. These outcomes suggest that in this drinking model, alcohol-induced neuroinflammation in the striatum is not a primary outcome controlling altered neurobehavioral function, but these changes are rather mediated by altered striatal neuronal structure and cellular health.Item eIF3a Regulates De Novo Fatty Acid Synthesis as an Alternative Mechanism in Cisplatin Response in Non-Small Cell Lung Cancer Cells(2024-08) Gu, Boqing; Jerde, Travis; Lu, Tao; Safa, Ahmad R.; Zhang, Jian-Ting; Wek, Ronald C.eIF3a is known to modulate DNA damage repair and cancer chemotherapy resistance partially via translational regulation of Raptor and its downstream mTOR pathway activity. Fatty acid synthase (FASN) has recently been reported to exert negative feedback on the mTOR signaling pathway, and FASN overexpression is associated with reduced chemotherapy efficiency in multiple cancer types. Here, we show that eIF3a exerts additional regulation on mTOR signaling pathway and chemotherapy resistance in non-small cell lung cancer by inhibiting FASN-mediated de novo lipid synthesis. Through genetic and chemical manipulations, we demonstrate that eIF3a physically interacts with the 5’-UTR of FASN mRNA to prevent FASN protein synthesis. Furthermore, FASN downregulation by eIF3a results in accumulation of malonyl-CoA, a substrate for fatty acid synthesis, which in turn directly inhibits mTOR activity of mTORC1 complex, decreasing NER protein level and cellular sensitivity to cisplatin in an eIF3a-dependent manner in addition to eIF3a-regulated expression of Raptor subunit in mTORC1. Taken together, our findings reveal a direct translational control of FASN-mediated fatty acid metabolism, suggesting a multi-level eIF3a regulatory paradigm on NER protein synthesis and activity during cancer cell response to cisplatin treatment.Item The Role of T Cells in Toxoplasma gondii-Induced Prostatic Hyperplasia(2024-08) Schmidt, Tara D.; Jerde, Travis; Arrizabalaga, Gustavo; Fehrenbacher, Jill; Relich, Ryan; Schmidt, NathanChronic inflammation is the most common histological feature in Benign Prostatic Hyperplasia (BPH), and T cells are a key component of immune infiltrate. Advanced BPH is commonly associated with the formation of nodules, but it remains unclear whether a link exists among T cell infiltration, nodular development, and BPH progression. Using a Toxoplasma gondii (T. gondii) model and human specimens, we characterize the subtypes of T cells present during prostatic hyperplasia and their association with nodular development of the prostate. Using flow cytometry, we found that infecting male mice with T. gondii resulted in an increase of both CD4+ and CD8+ T cells in the prostate that was most prominent at 14 days post-infection. Next, we established the presence of microglandular hyperplasia (MGH) and glandular nodule formation at this timepoint through hematoxylin and eosin (H&E) staining. Immunofluorescence revealed that CD8+ cells were found proximal to forming glandular nodules relative to non-nodular glands. We also found that more CD8+ cells localized to non-nodular glands in nodular BPH tissue versus non-nodular BPH tissue. Finally, we discovered a higher prevalence of CD8+ cells in T. gondii IgG+ patients than in IgG- patients. All T. gondii IgG+ patients exhibited nodular BPH, whereas all but one IgG- patient exhibited non-nodular BPH. This study is the first to identify the subsets of T cells in T. gondii-infected mouse prostates. Additionally, the locality of CD4+ and CD8+ T cells to nodular and non-nodular glands within our mouse model and human BPH prostate tissue has never been analyzed. Translationally, CD8+ T cells may enhance nodular BPH progression, and T. gondii infection may promote this CD8+ T cell-mediated response. Future work will focus on dissecting the molecular pathways induced by secreted factors from these CD8+ T cells that may contribute to epithelial cell proliferation and re-activation of glandular patterning in BPH.Item Pharmacological Depletion of Fibrinogen Suppresses the Growth of Primary Tumors and Metastasis of Pancreatic Ductal Adenocarcinoma (PDAC)(2024-08) Chowdhury, Nayela Nabiha; Fishel, Melissa L.; Yeh, Elizabeth; Pollok, Karen; Manchanda, Naveen; Jerde, Travis J.PDAC is a highly metastatic disease often linked to the dysregulated activation of both coagulation and fibrinolytic systems. Clinically, patients show elevated plasma fibrinogen levels, particularly in those with distant metastasis. The presence of systemic fibrinogen plays a crucial role in shaping the complex tumor microenvironment characteristic of PDAC, evidenced by the excessive deposition of its active substrate, fibrin, in PDAC tumors. To investigate its contribution to disease progression, fibrinogen was significantly depleted from the TME in multiple PDAC patient-derived xenograft (PDX) models, and the impact on tumor growth and metastasis was followed. In an aggressive, metastatic orthotopic Pa03C model, Fib depletion using antisense oligonucleotide (ASO) treatment markedly decreased the size of primary pancreatic tumors and subsequent spontaneous metastasis to the liver. Following implantation of tumor chunks (PDX21) from a patient with high Fib staining, Fib ASO treatment significantly diminished growth of primary tumors. Using a third orthotopic model (PDX33) and lipid nanoparticle (LNP)-encapsulated-siRNA to deplete the fibrinogen--chain, tumor growth was significantly reduced compared to control. This confirms that Fib deposition within the tumor microenvironment (TME) is an important driver of disease progression. Mechanistically, global proteomics revealed a remarkable upregulation of matrisome and extracellular matrix (ECM)-associated proteins, indicating that the reduction in primary orthotopic Pa03C tumors was associated with fibrin-mediated TME remodeling. Loss of fibrin matrices led to enhanced collagen, laminin, fibronectin and emilin1 deposition, and increased recruitment of collagen-producing αSMA+ myofibroblasts. Notably, our data suggests that fibrinogen depletion altered the ECM composition, inducing TME remodeling which led to stiffer tumors that are less metastatic. To further interrogate the role of fibrinogen in mediating metastasis, we employed an experimental metastasis model to study the colonization of tumor cells in the liver in the absence of fibrinogen. In this model, fibrinogen depletion did not impede the colonization of Pa03C cells, suggesting that fibrinogen does not mediate the colonization of tumor cells in the cascade of events for liver metastasis and is likely involved in one of the other steps of metastasis. Collectively, our data showed that pharmacologically reducing systemic fibrinogen levels impeded tumor growth and metastasis by remodeling the TME.Item Characterization of a Novel Hunk Inhibitor in HER2+ Breast Cancer(2024-07) Dilday, Tinslee Y.; Yeh, Elizabeth; Fehrenbacher, Jill; Brustovetsy, Nickolay; Safa, Ahmad; Sankar, UmaHuman Epidermal Growth Factor Receptor 2 (HER2)-targeted agents have proven to be effective, however, the development of resistance to these agents has become an obstacle in treating HER2+ breast cancer. Prior evidence implicates Hormonally Upregulated Neu-associated Kinase (HUNK) as an anti-cancer target for primary and resistant HER2+ breast cancers. An inhibitor Staurosporine (STU) has been identified as a HUNK inhibitor in HER2+ breast cancer. While STU was determined as a promising tool for inhibiting HUNK, it is a broad-spectrum kinase inhibitor and has not moved forward clinically. Therefore, identifying a more selective inhibitor of HUNK could be critical for targeting HUNK in HER2+ breast and understanding mechanisms by which HUNK promotes resistance to HER2-inhibitors. Specifically, HUNK has been implicated in promoting autophagy as a resistance mechanism in HER2+ breast cancer. Previously, we have identified that HUNK binds and phosphorylates an autophagy inhibitory protein, Rubicon, at Serine (S) 92 in 293T cells. This phosphorylation event causes Rubicon to switch to being an autophagy promoter. However, the role that Rubicon S92 plays in HER2+ breast cancer has yet to be examined. In this study, a novel inhibitor of HUNK is characterized alongside Rubicon S92 phosphorylation. This study establishes that HUNK-mediated phosphorylation of Rubicon at S92 promotes tumorigenesis in HER2/neu+ breast cancer. HUNK inhibition prevents S92 Rubicon phosphorylation in HER2/neu+ breast cancer models and inhibits both autophagy and tumorigenesis. This study characterizes a downstream phosphorylation event as a measure of HUNK activity and identifies a novel HUNK inhibitor that has meaningful efficacy toward HER2+ breast cancer.Item Dissecting the Role of Novel O-GlcNAcylation of NF-κB in Pancreatic Cancer(2024-06) Motolani, Aishat Abiola; Lu, Tao; Safa, Ahmad; Dong, Charlie; Pollok, Karen; Corson, TimothyPancreatic ductal adenocarcinoma (PDAC) is one of the most lethal malignancies, with a mere 5-year survival of ~10%. This highlights the urgent need for innovative treatment options for PDAC patients. The nuclear factor κB (NF-κB) is a crucial transcription factor that is constitutively activated in PDAC. It mediates the transcription of oncogenic and inflammatory genes that facilitate multiple PDAC phenotypes. Thus, a better understanding of the mechanistic underpinnings of NF-κB activation holds great promise for PDAC diagnosis and effective therapeutics. Here, we report a novel finding that the p65 subunit of NF-κB is O-GlcNAcylated at serine 550 and 551 upon NF-κB activation. Importantly, the overexpression of either serine-to-alanine (S-A) single mutant (S550A or S551A) or double mutant (S550A/S551A) of p65 in PDAC cells impaired NF-κB nuclear translocation, p65 phosphorylation, and transcriptional activity, independent of IκBα degradation. Moreover, the p65 mutants downregulate a category of NF-κB-target genes, which play a role in perpetuating major cancer hallmarks. We further show that overexpression of the p65 mutants inhibited PDAC cellular proliferation, migration, and anchorage-independent growth compared to WT-p65. We also show that inhibition of NF-κB O-GlcNAcylation may mitigate gemcitabine resistance and enhance its efficacy in PDAC cells. Collectively, our study uncovers a novel aspect of NF-κB regulation, which could aid future therapeutic development by targeting O-GlcNAc transferase (OGT) in pancreatic cancer.Item Elucidating the Influence of Microglia on Retinal Ganglion Cells in a Human Pluripotent Stem Cell Model(2024-06) Harkin, Jade; Meyer, Jason; Sheets, Patrick; Landreth, Gary; Block, Michelle; Sharma, Tasneem; Gomes, CatiaGlaucoma is a complex disease that leads to irreversible blindness, characterized by the loss of retinal ganglion cells (RGCs), which are the cells that transmit visual information from your eye into your brain. Evidence suggests that microglia, the resident immune cells in the central nervous system, may have a detrimental role in the onset and the progression of glaucoma. Microglia become activated in response to damage, pathogens and toxins and are initially thought to be beneficial to RGCs. However, when these cells are activated for excessive periods of time, they are thought to be harmful to RGCs. Thus, we sought to develop novel human pluripotent stem cell (hPSC)-derived microglia, astrocyte and RGC co-cultures to determine how microglia activation modulates RGC phenotypes in a human cellular model. Healthy and LPS-activated microglia were first co-cultured with RGCs for up to 3 weeks and the effects of microglia upon RGCs were assessed. Additionally, healthy and LPS-activated microglia were also co-cultured with astrocytes and RGCs for up to three weeks to assess if LPS-treated microglia can activate astrocytes and the effects this would have on RGCs. Results showed that when co-cultured with RGCs alone for 1 week, microglia activation is initially beneficial to RGCs. However, when co-cultured with RGCs for 3 weeks, microglia activation leads to RGC damage. Consequently, when astrocytes are present, microglia activation is harmful to RGCs in both short-term and long-term co-cultures, suggesting an additional role for microglia modulation of astrocytes, further leading to neurodegeneration. Taken together, our results have allowed for the precise study of how individual cell types are adversely affected in disease-relevant states, how microglia can directly influence RGCs, and how multiple co-cultures of human microglia, astrocytes and RGCs allows for a more sophisticated investigation of cellular interactions in disease states relevant to glaucoma.