Charles E. Schmidt College of Medicine

Serine/Arginine splicing factor 1 (SRSF1) is an RNA-binding protein (RBP) with multiple functions in RNA biogenesis. SRSF1 plays a prominent role in oncogenesis, immune function, and response to several physiological stimuli. To date, the role of SRSF1 as a regulator of mRNA splicing has been largely considered the main mechanism driving its biological functions and its role in disease. We have now characterized SRSF1’s role in Human Immunodeficiency Virus Type I (HIV-1) transcription. SRSF1 interacts with the 7SK small nuclear ribonucleoprotein (snRNP) to mobilize and activate the positive transcription-elongation factor (P-TEFb), which is then positioned on the HIV-1 promoter to increase the processivity of RNA polymerase II (RNAPolII) and promote the release of the negative regulators of transcription DSIF/NELF. Next, we defined the role of SRSF1 in the transcription of cellular genes utilizing an RNA sequencing (RNASeq) time course approach was used to detect changes in the transcriptome in response to SRSF1 overexpression. RNASeq data analysis revealed a subset of genes that were upregulated in response to SRSF1 overexpression. Nuclear run-on and qPCR assays experimentally validated 28 of these genes.

The structure and transparency of the eye lens are vital for focusing light onto the retina for vision. Lens fiber cells undergo a cellular remodeling program that removes mitochondria (MT), endoplasmic reticulum (ER), and Golgi apparatus (GA) to form mature transparent lens fiber cells. Previous studies established a requirement for the mitochondrial outer membrane protein BNIP3L for the elimination of these non-nuclear organelles in the lens; however, the precise molecular pathways for BNIP3L function remain to be elucidated. BNIP3L contains multiple functional domains whose analysis may illuminate its lens mechanisms including the LIR, BH3, and TM domains. These domains each play an important role in regulation of autophagosome formation and initiation of autophagy. To test each domain’s functionality for BNIP3L-dependent organelle elimination, we designed site-directed mutagenesis studies to delete each domain and test the resulting mutants in initiating the degradation of organelles in ex vivo cultured embryonic chick lenses.

Alzheimer’s disease is a neurodegenerative disease that causes cognitive dysfunction and leads to progressive memory loss and behavioral impairment. About 60% to 80% of dementia cases are attributed to Alzheimer’s disease and currently afflict about 50 million people worldwide. Although it primarily affects people over the age of 65, a person’s risk for developing Alzheimer’s disease earlier can depend on factors such as a family history (genetic inheritance) or experiencing an ischemic stroke event. Current treatments for Alzheimer’s disease include behavioral therapy and drug treatment that can lessen the severity of symptoms but cannot stop progression indefinitely. Sulindac is a non-steroidal anti-inflammatory drug that, by a mechanism independent of its anti-inflammatory properties, has shown to express a preconditioning response to protect from oxidative damage. Granulocyte colony stimulating factor is a hematopoietic glycoprotein that can stimulate the production of granulocytes and stem cells that has proven to provide neuroprotection in models of ischemic stroke via mechanisms including anti-apoptosis and anti-inflammation. In this in vitro study, the potential neuroprotective effects of Sulindac is measured against the effects of oxidative stress when subjected to hypoxia and reperfusion. Regarding un-transfected SHSY-5Y cells, hypoxia was demonstrated to lower cell viability starting at a period of 12 hours. It was found that a low concentration of Sulindac (200 uM) was effective in protecting SHSY-5Y cells against oxidative stress and overall lowering the rate of cell death in the event of hypoxic and reperfusion injury. When SHSY-5Y cells were transfected with Swedish APP mutation, cell viability was also markedly decreased in hypoxic conditions. However when treated with a concentration of 600 uM of Sulindac, cell viability levels were near matched with its normoxic counterparts

Studies suggest that smokers have less than optimal immune responses to natural infections and booster vaccines, which may adversely influence the herd effects of vaccines. We hypothesize that smoking attenuates preexisting memory cells and antibodies specific to childhood immunizations. To test this, we first evaluated several in vitro culture conditions that mimic in vivo immune cell responses within human blood samples. This study concluded that among tested conditions, R848/IL-2 and GMCSF/CD40L/IL-2 optimally supported the differentiation of existing antigen-specific memory B cells into immunoglobulin-secreting plasma cells. Additionally, GM-CSF optimally supported the differentiation of antigen-specific memory T cells into IFN-γ- producing effector cells. Overall, we have established culture conditions that will allow us for the first time to assess the impact of external factors (i.e., smoking, immunosuppressive drugs, etc.) on preexisting, development, and longevity of immune memory specific to childhood, booster, and new vaccines among various populations.

The largest barrier to treatment of HIV-1 infection is the establishment of a viral reservoir constituted mostly by quiescent latently infected CD4+ T cells. This reservoir is formed through two processes: i) the infection of resting CD4+ T cells; both naïve and memory, ii) the infection of activated CD4+ T cells which then become quiescent infected cells. One goal of this project was to understand the gene expression changes occurring in naïve CD4+ T cells following activation and subsequent HIV-1 infection and how this may contribute to the establishment of a latent infection in these cells. Utilizing RNA-Seq and a series of validation assays we have identified several genes which are regulated in opposite directions during activation versus infection which we termed DEOC genes. The DEOC genes include a group of physically- and functionally-associated proteins which are key regulators of T cell activation, the cell cycle, cellular proliferation, and cellular quiescence, suggesting that modulation of these DEOC genes may help transition the infected-activated cell from an activated state to a quiescent/resting state to induce a latent infection.

Unintentional weight loss in older adults often precedes Alzheimer’s disease (AD). Positron emission tomography (PET) scan reveals that AD patients exhibit reduced uptake of fluorodeoxyglucose into brain cells, defined as ‘hypometabolism’. However, cellular mechanisms underlying weight loss and hypometabolism have not received much attention. The primary goal of the study was to test the hypothesis that cells become starved in confrontation with amyloid beta proteins (Aβ), which are increasingly aggregated in the AD brain. Cellular ATP is known as a biomarker indicating for cell starvation. We found that Aβ caused a dose-dependent reduction in ATP of astrocytes. This effect was similar to those of cells being deprived from nutrients (i.e., glucose, pyruvate and glutamine). Together, the data of the present study support the hypothesis that cell starvation is likely associated with weight loss and hypometabolism in AD patients.

Abnormal vasculature in the retina, specifically tortuous blood vessels, are common to many of the most prevalent retinal degenerative diseases currently affecting millions across the world. The mechanisms of their formation and development in the context of retinal degenerative disease, however, are still poorly understood. The rd1 and rd10 mice are relatively well-studied animal models of retinal degenerative disease, however, there lacks a systematic characterization of vascular changes co-related to photoreceptor degeneration in the rd1 and rd10 retina. Here, we utilize advancements in confocal microscopy, immunohistochemistry, and image analysis software in order to systematically characterize vascular changes before and after retinal development in the rd1 and rd10 mice. We show that there are plexus specific changes in the retinal vasculature that parallel photoreceptor degeneration. Such information will be of particular use to future studies investigating the role of vascular changes in retinal degenerative disease therapies.

Cerebrovascular events (stroke) are a significant cause of morbidity and mortality worldwide. Ischemic stroke accounts for ~85% of all strokes and is caused by the blockade of blood flow to a certain area of the brain, resulting in oxygen and nutrient deprivation and ultimately cell death. Cerebral ischemia induces a strong neuroinflammatory response that contributes to tissue damage and is driven by changes in the gene expression profile and phenotype of brain cells including neurons, astrocytes, and microglia. Microglia are the resident immune and phagocytic cells of the central nervous system. They rapidly respond to ischemia by migrating to the site of injury and modulating the inflammatory response there. Although microglia may play a deleterious role in the acute phase of stroke, evidence suggests that they play an important role in the reduction of excitotoxic injury as well as in neurogenesis during the tissue regeneration phase. Granulocyte-colony stimulating factor (G-CSF) is a hematopoietic growth factor that has shown beneficial effects in models of ischemic stroke. G-CSF exerts its neuroprotective effects through different mechanisms including mobilization of haemopoietic stem cells, angiogenesis, neurogenesis, anti-inflammation, and anti-apoptosis. However, its effect on microglia is not well understood yet. The main objective of this project was to evaluate the protective and anti-inflammatory effect of G-CSF gene therapy against glutamate cytotoxicity in the human microglial clone 3 cell line (HMC3). Our results show that although G-CSF gene therapy did not significantly protect HMC3 cells against glutamate induced cell death, it reduced the expression levels of pro-inflammatory proteins NF-κB p65, IL-1β and IL-6, while increasing the phosphorylation of Akt, a regulator of cell survival and proliferation.

Ischemic stroke is defined as a blockage or reduced flow of blood to select areas of brain tissue due to either plaque formation or buildup of blood clots in the small blood vessels. A characteristic of sickle cell anemic patients is the potential for them to experience a similar type of blockage due to the sticky nature of the sickled red blood cells as well as defective oxygen delivery to the brain. Because of this similarity, sickle cell anemia may represent a good animal research model for therapeutic intervention based on stroke models. In recent studies, Granulocyte-Colony Stimulating Factor (GCSF), has been shown to exhibit a robust range of neuroprotective properties against neurological disorders including ischemic stroke through preservation of the endoplasmic reticulum (ER) by modulating various ER stress pathways. Through cognitive deficit analysis in the form of behavioral and locomotor experiments in addition to in situ biomarker analysis by way of western blotting and immunohistochemistry, we found that G-CSF gene therapy exhibited neurogenic and neuroprotective effects in ischemic mouse models and could possibly serve as a good therapy for other diseases that share similar pathology to stroke.

The kynurenine pathway plays a critical role in regulating immunological homeostasis in the brain. Evidence supporting the hypothesis that kynurenine pathway dysfunction may exacerbate progression of neurodegenerative diseases like Parkinson’s is growing. First, we investigate the effects of Interferon-γ, Lipopolysaccharide, and Interleukin-4 on several key kynurenine pathway metabolites using high performance liquid chromatography. We found that Interferon-γ had significant effects on the extracellular concentration of kynurenine metabolites in astrocytes, microglia, and macrophage. GCSF gene therapy is previously demonstrated to exert neuroprotective effects on models of Parkinson’s and Alzheimer’s disease. Seven days after receiving GCSF gene therapy, A53T Parkinson’s mice were found to have increased levels of GCSF and tyrosine hydroxylase positive neurons. A concurrent increase in expression of the kynurenine pathway enzyme kynurenine aminotransferase 2 was observed. GCSF gene therapy may exhibit neuroprotective effects in a Parkinson’s disease mouse model by restoring this key kynurenine pathway enzyme.