The last decade for the Medical College of Georgia has yielded strategic, phenomenal growth in educational, research and clinical initiatives in diseases affecting every family in Georgia and the United States.

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Recent Submissions

  • DEVELOPMENT OF TRANSGENIC ZEBRAFISH MODEL FOR INVESTIGATION OF THE FUNCTION OF MICROGLIA

    Sura, Survasha; Department of Biological Sciences; Department of Biochemical and Molecular Biology; Georgia Cancer Center; Rajpurohit, Surendra K; Augusta University (2019-02-13)
    Zebrafish have emerged as a powerful model organism for elucidating the development and function of microglia. Generation of new transgenic reporter lines and imaging tools strengthen the zebrafish model in microglia study�in-vivo. The aim is to develop a novel compound transgenic line to study the inflammatory process mediated by NF-kB in microglia cells. This novel compound transgenic line will establish a new model for microglia study. To generate the novel compound zebrafish transgenic model for microglia, we are crossbreeding microglia transgenic line zebrafish (Tg(mpeg1:mCherry) with the NF-kB Tg(6xNFkB:EGFP) transgenic progeny. We first generate a heterozygous F1 progeny which will be bred to generate an F2 homozygous progeny. Once the F1 progeny of the Microglia-NfkB transgenic line is developed, they will be crossbred to develop the Homozygous compound transgenic line. Fluorescent Microscopy will be used to screen the larvae generated from the breeding events. By developing the compound transgenic line, we are optimizing microglia isolation and sorting methodology by using the related antibodies as the marker. The NF-kB microglia transgenic line will provide a unique platform for drug screening to address microglial based ailments, thus furthering the understanding and treatment of human disease.
  • SMALL AND DANGEROUS: MICRORNA-21 AND BLINDNESS

    Rajpurohit, Shubhra; Department of Ophthalmology; Thounaojam, Menaka C; Jadeja, Ravirajsinh; Gutsaeva, Diana; Bartoli, Manuela; Augusta University (2019-02-13)
    Retinal neovascularization (RNV) is a potentially blinding condition characterized by the development of small, leaky, abnormal, blood vessels in the retina. This occurs as a consequence of retinal ischemia, which promotes the release of angiogenic factors such as vascular endothelial growth factor (VEGF). MicroRNAs (miRs) are non-coding RNA involved in post-transcriptional regulation of genes resulting in the blockade of their expression. MiRs are key players in a wide range of biological processes such as cell differentiation, neurogenesis, viral infection, immunity, and hypoxia. More specifically, microRNA-21 (miR-21) is upregulated in many pathological conditions including cancer, and cardiovascular disease. Previously, we have shown that microRNA-21 (miR-21) is a downstream effector of the transcription factor Signal Transducer and Activator of Transcription 3 (STAT3) in retinal endothelial microvascular cells. Here, we will identify new therapeutic targets as well as diagnostic tools to prevent retinal neovascularization and, potentially, other ocular diseases. One well-known retinal angiostatic factor is pigmented epithelium-derived factor (PEDF). Increased miR-21 expression in the ischemic retina affects PEDF �gene� expression. Interestingly, miR-21 is known to inhibit the expression of peroxisome proliferator-activated receptor alpha (PPAR?). PPAR? is a transcription factor for PEDF; therefore, increased miR-21 level in the ischemic retina could lead to inhibition of PPR alpha expression and consequent inhibition of PEDF expression.
  • EFFECT OF GABAERGIC NEURONS IN SUSCEPTIBLE VERSUS RESILIENT MALE RATS TO PTSD

    Dixon, Rachel; Mandavilli, Rohan; Department of Phychological Sciences; Department of Biological Sciences; Departmetn of Pharmacology & Toxicology; Bunting, Kristopher M; Alexander, Khadijah; Vazdarjanova, Almira; Augusta University (2019-02-13)
    Post-traumatic stress disorder (PTSD) is a psychological disorder that can occur after a traumatic event. Individuals with PTSD exhibit extreme anxiety and learning and memory difficulties. Once exposed, 12-35% develop PTSD with women twice as likely to be affected than men. Our goal is to discover underlying mechanisms to prevent PTSD, as we investigate the relevance of glutamic acid decarboxylase positive (GAD+) neurons on susceptible (SUS) and resilient (RES) male rats. SUS and RES phenotypes were assessed using the highly advanced RISP protocol to reveal susceptibility to a PTSD-like phenotype. The increase of GAD+ cells in the medial prefrontal cortex (mPFC) informs us that more GABAergic neurons are present, which can cause inappropriate recall. We will be examining if there is a difference in the number of GAD+ cells in the RES versus SUS male rats. To investigate, we used cryosectioned brains from SUS or RES rats. The brains were stained using immunohistochemistry to isolate the GAD+ neurons in the mPFC and were counted. The results of this experiment will be determined and examined at a later date closer to our presentation. We expect to see a SUS male rats to have a higher number of GAD+ neurons.
  • THE MECHANISM OF INVERSE AGONISTS ON HISTAMINE RECEPTORS, HISTAMINE RECEPTOR H1, AND HISTAMINE RECEPTOR H2

    Patel, Shrey P; Department of Phychological Sciences; Department of Pharmacology & Toxicology; Lambert, Nevin; Augusta University (2019-02-13)
    The experiment discusses the role of inverse agonist binding to receptors and how its effect cell signaling. The specific receptors that was focused on in the project was histamine receptor H1 (HRH1) and histamine receptor H2 (HRH2) which are types of G-protein coupled receptors (GPCR). Both receptors are activated when a ligand, specifically a histamine molecule, which binds to the receptor and activates the signaling pathway within the cell. The main protein within the signaling pathway is the G-protein which helps the cascade effect of the signal to other molecules. G-proteins are activated through GTP. An inverse agonist works like an agonist but will have an opposite end effect within the cell. It was originally thought that inverse agonist works the same way as an agonist to recruit a GTP and activate a G-protein for signaling. The experiment being tests tries to explain the opposite that the inverse agonist could activate the protein without GTP and continue to have its effect on the cell. Human embryonic cells were transfected with plasmids that contain sequences for the receptors and the G-protein, which were also tagged with a fluorophore to measure any bioluminescence with interaction of G-protein and the receptor when the ligands binds. From collecting data from the bioluminescence effect, it shows that there is an interaction a receptor and G-protein complex when the inverse agonist is bound.
  • EFFECTS OF VITAMIN D3 DEFICIENCY, VITAMIN D RECEPTOR KNOCKOUT, AND DIABETES ON CORNEAL EPITHELIAL NERVE DENSITY

    Vick, Sarah; Department of Biological Sciences; Department of Cellular Biology and Anatomy; Lu, Xiaowen; Watsky, Mitchell; Augusta University (2019-02-13)
    It is estimated that 41.6% of the US population suffers from vitamin D deficiency, with Blacks (82.1%) and Hispanics (69.2%) at even greater risk�Vitamin D deficiency can be caused by a variety of sources and given the wide range of causes, it is important to understand what measures this population might take to proactively prevent greater harm, or to reverse harm that might have already occurred. This project is designed to test the general hypothesis that Vitamin D deficiency exacerbates preexisting primary corneal pathologies. Previous research has established that the corneal epithelium in diabetic mice heals at a faster rate than the epithelium in diabetic vitamin D receptor (VDR) knockout (KO) mice. It is known that within diabetic mice, the corneal nerve density is decreased. However, it is unknown how VDR KO mice or vitamin D deficient with diabetes will affect corneal nerve density. In order to identify variabilities within the nerves that indicate slow wound healing, the mouse corneas will be collected, stained for confocal microscope observation, and analyzed through image processing to determine nerve density.
  • ADIPOSE HDAC9 DELETION PROTECT AGAINST DIET INDUCED OBESITY IN MICE THROUGH REGULATING ENERGY EXPENDITURE

    Hassan, Nazeera; Zarzour, Abdalrahman; Department of Biological Sciences; Department of Medicine; College of Allied Health Sciences; Kim, Ha Won; Weintraub, Neal; Augusta University (2019-02-13)
    Our group has previously identified histone deacetylase 9 (HDAC9) as a regulator of adipocyte differentiation, and its expression levels were elevated in diet induced obese (DIO) mice.� We also reported that global HDAC9 deletion protected mice against DIO through promoting beige adipogenesis. Here, we hypothesized that adipose HDAC9 correlate with human obesity similar to murine models, and its deletion is sufficient to protect against DIO. To test this hypothesis we crossed HDAC9 floxed mice with adiponectin-cre mice to generate adipose-specific HDAC9 knockout mice (AdipCre-HDAC9), which exhibited 30% less weight gain when fed high fat diet compared to control despite increased food intake, in association with increased energy combustion & O2 consumption, improved insulin sensitivity and glucose tolerance. However, unlike global HDAC9 deletion, this was not associated with increased beige adipogenesis nor increase in brown adipose tissue function. Interestingly, AdipoCre-HDAC9 mice fed normal chow diet didn�t exhibit altered energy expenditure nor weight differences when compared to littermate controls. These finding suggest that adipose HDAC9 regulate energy expenditure in response to high fat diet and can be a promising therapeutic target to combat obesity.
  • MIRNA AND THEIR EFFECTS ON BONE LOSS IN TRAUMATIC BRAIN INJURY PATIENTS

    Patel, Chandani; Patel, Reeya; College of Science and Mathematics; Department of Orthopedic Surgery; Fulzele, Sadanand; Augusta University (2019-02-13)
    MicroRNAs (miRNAs) have been known to play a key role in bone regulation. Some miRNAs have been observed to increase bone formation via osteoblast formation and others seem to be involved in bone resorption via osteoclast formation. In this study, we aim to observe which miRNA of those secreted by cells during a traumatic brain injury (TBI) are involved in bone formation or bone resorption. Our focus miRNAs were: miRNA-151, miRNA-6991, miRNA-27a, miRNA-92, and miRNA-1224. Using mouse bone marrow monocytes (BMCs), we have induced osteoclast formation by feeding media containing macrophage colony stimulating factor (M-CSF) as well as receptor activator of nuclear factor kappa-B ligand (RANK-L). After osteoclastogenesis, it has been observed via tartrate resistant acid phosphatase (TRAP) staining that miRNA-151 and miRNA-6991 have been up-regulated during osteoclast differentiation. Of the ones examined in our study, miRNA-27a, miRNA-92, and miRNA-1224 have shown an increase during osteoblast differentiation. The observations from this study can contribute insight for creating possible therapeutic methods for osteoporosis related diseases.
  • Unconventional Coupling of 5HT7 receptors to Gs heterotrimers

    Adams, Elizabeth; Department of Pharmacology and Toxicology; Lambert, Nevin; Augusta University (2019-02-13)
    GPCRs play a major role in cell signaling through their interactions with heterotrimeric G proteins. In conventional models of GPCR-G protein coupling, agonist binding promotes a conformational change within the receptor, which then associates with G proteins, facilitating the exchange of GDP for GTP. GTP-bound G proteins dissociate from the receptor and exert their effects on downstream signaling molecules. Previous studies suggest that serotonin 5HT7 receptors associate with Gs�heterotrimers prior to agonist binding, and that 5HT7-Gs�complexes dissociate after the G protein is activated. Here we study this unconventional mode of coupling using bioluminescence resonance energy transfer (BRET) between luciferase-tagged 5HT7 receptors and Gs�heterotrimers labeled with Venus. Our results confirm that 5HT7 receptors interact with inactive (GDP-bound) Gs�heterotrimers in the absence of an agonist, and that this interaction is stabilized by the inverse agonist methiothepin. Stimulation with the endogenous agonist serotonin (5HT) decreased BRET between 5HT7 receptors and Gs, indicating that the activation of the receptor leads to 5HT7-Gscomplex dissociation. Interestingly, Gs�activation was not required for complex dissociation. These results are consistent with the hypothesis that 5HT7 receptors couple to Gs�heterotrimers via an unconventional mechanism involving ligand-sensitive complexes of receptors and inactive Gs.
  • The Study of 5ht-1d and 5ht-1f Receptor Interactions with Mini G Proteins via Bret Analysis

    Trang, Amy; Department of Chemistry & Physics; Department of Pharmacology and Toxicology; Spencer, Angela; Lambert, Nevin; Augusta University (2019-02-13)
    G protein-coupled receptors (GPCRs) are receptors involved in signal transduction, a process for converting extracellular signals into internal messages to elicit a cellular response. Signal transduction pathways involve activating various G protein subtypes (Gs, Gi/o, Gq/11�and G12/13) which typically lead to second messenger production. Traditionally, second messenger concentration assays are used to identify GPCR coupling with G protein(s), but they are not efficient in profiling GPCRs since they compare the concentrations from different downstream signals. Instead, novel tools, such as Bioluminescence Resonance Energy Transfer (BRET) and mini G (mG) proteins, can be used to profile GPCRs. BRET is a technique that provides quantitative data when protein-protein interaction occurs and requires the proteins of interest to be fused with either a bioluminescent protein or fluorescent protein. In this study, we used mG proteins representing each G protein subtype to identify 5-hydroxytryptamine (5-HT; serotonin) receptor coupling upon serotonin stimulation. Through BRET assays, we determined that both the 5-HT1D�and 5-HT1F�receptors couple primarily with the mGsiand mGo�classes of mG proteins. This supports previous studies that these receptors couple to Gi/o�proteins and suggests that the use of mG proteins in BRET assays is an effective tool for GPCR profiling.
  • The Identification of Novel Genes in Normosmic Hypogonadotropic Hypogonadism (nHH)

    Smith, Hannah; College of Education; Department of Obstetrics & Gynecology; Layman, Lawrence; Augusta University (2019-02-13)
    Characterized by delayed or absent sexual development, idiopathic hypogonadotropic hypogonadism (IHH) is a disorder that includes the deficient production, secretion, or action of gonadotropin-releasing hormone (GnRH). Producing neurons in the brain, GnRH directly controls sexual development during puberty. Misplacement of the GnRH producing neurons leads to hypogonadotropic hypogonadism, which is divided into two categories: Kallmann syndrome (KS) and normosmic IHH (nHH). While both KS and nIHH, defined as the absence or delay of puberty, low gonadotropins and sex steroids, are similar, KS also includes the absence or impairment of smell. Whole exome sequencing (WES) is used to examine protein-coding regions of the human genome in order to detect genetic variants that could be causative. Sanger sequencing is used to confirm variants identified by WES. Using WES and Sanger sequencing, we were able to identify new genetic variants within the nHH and KS patient populations. In this study, our goal was to identify pathogenic variants in known and novel nHH/KS genes, focusing efforts on rare, loss-of-function variants in: WDR11, GLI2, CTNNA1, ANKHD1, SEMA6A, PRRC2C, EHBP1, and RIF1 genes. This study broadens our understanding of pathogenic variants in known and novel IHH genes that may contribute to the disease phenotype.
  • TWO-SAMPLE TESTS FOR HIGH DIMEMSIONAL MEANS WITH PREPIVOTING and DATA TRANSFORMATION

    Hellebuyck, Rafael Adriel; Department of Biostatistics and Epidemiology (2019-01-08)
    Within the medical field, the demand to store and analyze small sample, large variable data has become ever-abundant. Several two-sample tests for equality of means, including the revered Hotelling’s T2 test, have already been established when the combined sample size of both populations exceeds the dimension of the variables. However, tests such as Hotelling’s T2 become either unusable or output small power when the number of variables is greater than the combined sample size. We propose a test using both prepivoting and Edgeworth expansion that maintains high power in this higher dimensional scenario, known as the “large p small n ” problem. Our test’s finite sample performance is compared with other recently proposed tests designed to also handle the “large p small n ” situation. We apply our test to a microarray gene expression data set and report competitive rates for both power and Type-I error.
  • Immune regulation of tumor cell plasticity: A promising molecular target in breast cancer metastasis

    Korkaya, Hasan; LEE, EUNMI; Department of Biochemistry and Molecular Biology / Cancer Center (2018-11-29)
    It is widely accepted that phenotypic plasticity of malignant cells is required during metastatic cascade. However, the specific mechanism of how the tumor microenvironment regulates tumor cell plasticity in metastasis is under intense investigation. We demonstrate here that monocytic and granulocytic subsets of myeloid-derived suppressor cells (MDSC), hereafter called mMDSCs and gMDSCs, infiltrate in the primary tumor and distant organs with different time kinetics and regulate spatiotemporal tumor plasticity. Using co-culture experiments and mouse transcriptome analyses in syngeneic mouse models, we provide evidence that tumor-infiltrating mMDSCs facilitate dissemination from the primary site by inducing the EMT/CSC phenotype. In contrast, pulmonary gMDSC infiltrates support metastatic growth by reverting the EMT/CSC phenotype and promoting tumor cell proliferation. We also observe that lung-derived gMDSCs isolated from tumor-bearing mice enhance metastatic growth of already disseminated tumor cells. Our ongoing studies reveal that calprotectin (S100A8 and S100A9 heterotetramer) is an important regulator of gMDSCs, which play a critical role in promoting breast cancer metastasis by inducing MET-like CSCs as well as suppressing anti-tumor immunity within the pre-metastatic niche. Furthermore, we develop a novel gMDSC-targeting compound that potentially binds to calprotectin and validate its therapeutic utility in a preclinical breast cancer model. Our goal for this study is to elucidate the molecular co-evolution of tumor and immune cells in cancer development and to identify molecular targets to provide alternative therapeutic options for women with metastatic disease.
  • Anterograde and Retrograde Regulation of Neuromuscular Junction Formation and Aging

    Mei, Lin; Zhao, Kai; Department of Neuroscience and Regenerative Medicine (2018-11-29)
    The neuromuscular junction (NMJ) is a chemical synapse that facilitates the neuronal control of muscle contraction. Proper NMJ formation and maintenance require both anterograde and retrograde signaling. In this study, on one hand, we characterized the role of Yes-associated protein (Yap) in the formation of neuromuscular junction (NMJ). In HSA-Yap-/- mice where Yap was mutated specifically in muscle cells, AChR clusters were smaller and distributed in a broader region in the middle of muscle fibers. In addition, HSA-Yap-/- mice also exhibited remarkable presynaptic deficits including less nerve coverage of the endplates, reduced mEPP frequency and increased paired-pulse facilitation, indicating structural and functional defects. Moreover, muscle Yap mutation prevented reinnervation of denervated muscle fibers and the phenotypes were related to compromised β-catenin signaling. Both NMJ formation and regeneration deficits of HSA-Yap-/- mice were ameliorated by inhibiting β-catenin degradation, further corroborating a role of β-catenin as a downstream molecule of Yap to regulate NMJ formation and regeneration. On the other hand, we showed that Lrp4, a receptor for agrin and critical for NMJ formation and maintenance, was reduced at the protein level in aged mice, which was associated with decreased MuSK tyrosine phosphorylation, suggesting compromised agrin-Lrp4-MuSK signaling in aged muscles. Transgenic expression of Lrp4 in muscles alleviated AChR fragmentation and denervation and improved neuromuscular transmission in aged mice. Lrp4 ubiquitination was augmented in aged muscles, suggesting increased Lrp4 degradation as a mechanism for the reduced protein level. We also found that sarcoglycan alpha (SGα) interacted with Lrp4 and delayed Lrp4 degradation in co-transfected HEK293 cells. AAV9-mediated expression of SGα in muscles mitigated Lrp4 degradation and NMJ decline in aged mice. These observations support a model where compromised agrin-Lrp4-MuSK signaling serves as a pathological mechanism of age-related NMJ decline and identify a novel function of SGα in stabilizing Lrp4 for NMJ maintenance in aged mice.
  • ENCODING OF EPISODIC EVENTS BY THE RETROSPLENIAL CORTEX

    Fox, Grace Ellen; Department of Neuroscience and Regenerative Medicine (8/7/2018)
    Fear is an adaptive response that permits organisms to reduce or avoid danger. In many animal species, behavioral correlates of fear can be seen, which highlights its essential role in survival; conversely, inappropriate and exaggerated fears are a hallmark of psychiatric disorders, such as anxiety-related disorders. Recently, the retrosplenial cortex (RSC) has been implicated for long-term storage of fear-related memories. However, the basic physiological properties of RSC cells as well as their response to fearful events remained largely unexplored. Our experiments demonstrate that excitatory principal cells within RSC layers 2&3 and 5&6 contain multiple physiologically distinct sub-populations that are differentially affected by ketamine. We also demonstrate the novel finding that the RSC utilizes the specific-to-general cell-assembly logic for processing neural information about fearful experiences. Taken together, these results illustrate that the RSC generates a cell assembly-level representation of fear memory engrams and supports the pursuit of the RSC as a therapeutic target for anxiety-related disorders.
  • Effect of chronic oral treatment with risperidone or quetiapine on cognitive performance and neurotrophin-related signaling molecules in rats

    Poddar, Indrani; Department of Pharmacology and Toxicology (8/7/2018)
    Antipsychotic (APs) drugs are among the top selling pharmaceuticals in the world and they have a variety of important therapeutic applications for neuropsychiatric disorders. However, there are a number of controversies related to this class of agents and many of the relevant questions are difficult to prospectively address in the clinical trial environment. For example, there have been multiple clinical trials for pro-cognitive agents in schizophrenia that have failed; however, the question of how chronic prior treatment with APs might influence the response to a pro-cognitive agent was not addressed. Moreover, there is clinical evidence that chronic treatment with some APs may lead to impairments in cognition, however, this issue and the potential molecular mechanisms of the deleterious effects have been not been prospectively addressed. Accordingly, the purpose of the work described in this dissertation was to prospectively address each of these issues in animals (specifically rats) were environmental conditions can be rigorously controlled. In each of the manuscripts included in this dissertation, two of the most commonly prescribed APs, risperidone and quetiapine were evaluated. In the work conducted in Manuscript 1, we established a therapeutic relevant dosing approach for rats (oral administration in drinking water) and reinforced the argument that these two APs are not pro-cognitive agents. Moreover, we determined that alpha-7 nicotinic acetylcholine receptor (nAChR) ligand like tropisetron has potential as an adjunctive medication in schizophrenia since the pro-cognitive effect was maintained in the presence of chronic AP treatment. In Manuscript 2, we concluded that chronic treatment with risperidone or quetiapine in rats can lead to impairments in a domain of cognition (recognition memory) that is commonly altered in neuropsychiatric disorders. Moreover, the negative effects of the APs appeared to be exacerbated over time. In Manuscript 3, we concluded that risperidone and quetiapine when administered chronically to rats have the potential to adversely affect neurotrophin-related signaling molecules that support synaptic plasticity and cognitive function. These data would suggest that the extensive prescribing of these APs across multiple conditions in patients ranging in age from the very young to the very old should be carefully reexamined. Key Words: antipsychotic, cognition, brain volume, schizophrenia, neurotrophin
  • Canonical Wnt Signaling in Antigen Presenting Cells Regulates Microbiota-Induced Inflammation and Immune Cell Homeostasis in the Colon

    Swafford, Daniel Joseph; Department of Biochemistry and Molecular Biology / Cancer Center (8/3/2018)
    Aberrant Wnt/β-catenin-signaling occurs in several inflammatory diseases including inflammatory bowel disease (IBD) and IBD-associated colon carcinogenesis. However, its role in shaping mucosal immune responses to commensals in the gut remains unknown. Here, we investigated the importance of canonical Wnt signaling in CD11c+ antigen presenting cells (APCs) in controlling intestinal inflammation. Using a mouse model of ulcerative colitis, we demonstrated that canonical Wnt-signaling in intestinal CD11c+ antigen presenting cells (APCs) controls intestinal inflammation by imparting an anti-inflammatory phenotype. Genetic deletion of Wnt co-receptors, low-density lipoprotein receptor-related protein 5 and 6 (LRP5/6) in CD11c+ APCs in mice (LRP5/6ΔCD11c mice) resulted in enhanced intestinal inflammation with increased histopathological severity of colonic tissue. This was due to microbiota-dependent increased production of pro-inflammatory cytokines and decreased expression of immune regulatory factors such as IL-10, retinoic acid (RA), and IDO. In addition, loss of LRP5/6-mediated signaling in CD11c+ APCs resulted in altered microflora and T cell homeostasis, which led to a loss of systemic tolerance to oral antigen. Furthermore, our study demonstrates that conditional activation of β-catenin in CD11c+ APCs in LRP5/6ΔCD11c mice resulted in reduced acute intestinal inflammation with decreased histopathological severity of colonic tissue. Loss of canonical Wnt signaling in CD11c+ APCs also results in an increase in colonic polyp formation and exacerbation of chronic inflammation/injury. This was also heavily dependent on the presence and composition of the gut microbiota, as fecal transfers from LRP5/6ΔCD11c mice to floxed control (LRP5/6FL/FL) mice that were administered an antibiotic cocktail produces a polyp load and weight loss similar to that of LRP5/6ΔCD11c mice without treatment. Additionally, our study demonstrates that conditional activation of β-catenin in CD11c+ APCs in LRP5/6ΔCD11c mice reduces severity of inflammation-associated colon carcinogenesis in these mice. Furthermore, we show that treatment of LRP5/6ΔCD11c mice with either RA or IL-10 reduces severity of inflammation-associated colon carcinogenesis. Mechanistically, RA and IL-10 may independently reduce key inflammatory factors at the acute phase of colitis. These results ultimately reveal a mechanism by which intestinal APCs control intestinal inflammation and immune homeostasis via the canonical Wnt signaling pathway, which may serve as a promising target for chronic inflammatory disorders.
  • NAE1-MEDIATED NEDDYLATION IS REQUIRED FOR POSTNATAL LIVER DEVELOPMENT AND FUNCTION

    Sahay, Khushboo; Department of Physiology (7/26/2018)
    Liver disease is an important health concern and a significant source of morbidity and mortality in the United States and worldwide. NEDD8 (neural-precursor-cell-expressed developmentally down-regulated 8) is a novel ubiquitin-like protein modifier. The conjugation of NEDD8 to target proteins, termed neddylation, requires NEDD8 specific E1, E2 and E3 ligases. Neddylation participates in various cellular processes. However, whether neddylation regulates liver development and function is completely unknown. We created mice with hepatocyte specific deletion of NAE1, a subunit of the only NEDD8 E1 enzyme, and identified that they display severe hepatomegaly, hypertriglyceridemia, and hypercholesterolemia from 10 days after birth. By postnatal 14 days, their liver cytoarchitecture is completely disrupted, along with formation of numerous biliary cysts, fibrosis and hypoglycemia, which ultimately result in liver failure and premature death by 6 weeks. Mechanistically, NAE1 deficiency in hepatocytes caused reduced hepatocytespecific gene expression but increased biliary/oval cell gene expression in liver. In vitro, NAE1 inhibition by MLN4924 and CRISPR/Cas9-mediated NAE1 deletion in HepG2 cells recapitulated in vivo findings with repressed expression of hepatocyte specific genes but elevated biliary/oval cell gene expression. Together, these data highlight an essential role for neddylation in regulating hepatocyte lineage commitment and function as well as polycyst formation through trans/de-differentiation of hepatocytes.
  • Using peptide-based vaccines to enhance adoptive cell therapy with genetically engineered T cells

    Celis, Esteban; Fan, Aaron; Department of Neuroscience and Regenerative Medicine (6/27/2018)
    Adoptive cell therapy (ACT) of retrovirally transduced (RV) CD8 T cells is a powerful technique that has shown promise in tumor eradication in cancer patients. However, some major barriers to current methods are that ACT is expensive, time consuming, and requires harmful and toxic adjunct procedures. The Celis laboratory has demonstrated the use of TriVax, a potent peptide vaccination strategy that dramatically expands ACT cell populations and bypasses the necessity for adjunct procedures. The purpose of my thesis project was to enhance current methods of ACT+TriVax by testing an antigen-specific antitumor response of RV CD8 T cells and if it could be improved with constitutively active STAT5 (CA-STAT5) expression, a protein activated downstream several cytokine pathways that have been shown to play a role in increasing CD8 T cell persistence and resistance to apoptosis. Here, I aimed to test the hypothesis that CA-STAT5 in CD8 T cells enhances an antitumor effect by increasing T cell persistence and efficacy. My results show that TriVax administration selectively expanded frequencies of the ACT cell population expressing gp100-TCR in both blood and spleen. When co-transduced with CA-STAT5, an even higher fold expansion of antigen-specific cells was observed. +CA-STAT5 T cells were able to expand more robustly than -CA-STAT5 T cells upon repeated antigen stimulation (vaccine boost), demonstrating nearly 4000-fold increases in antigen-specific CD8 T cells. +CA-STAT5 T cells also seemed to persist longer in vivo over time, and they expressed lower levels of surface PD-1. Using B16F10 melanoma, ACT+TriVax of these cell populations into tumor-bearing mice demonstrated a powerful antitumor effect, leading to tumor regression in treated groups. CA-STAT5 seemed to recapitulate similar antitumor effects our laboratory observed previously with combinatorial anti-PD-L1 treatment or IL2/anti-IL2 mAb complexes (IL2Cx), suggesting a potential role for STAT5 in resisting the PD-1/PD-L1 inhibitory pathway. Altogether, these results demonstrate that RV CD8 T cells expressing gp100-TCR and CA-STAT5 are capable of antigen-dependent expansion in response to TriVax. CA-STAT5 plays a role in increasing T cell proliferation and persistence, as well as increasing efficacy through resistance to PD-1/PD-L1 inhibition.
  • MECHANISM OF 12/15 LIPOXYGENASE-INDUCED RETINAL MICROVASCULAR DYSFUNCTION IN DIABETIC RETINOPATHY

    Elmasry, Khaled; Department of Biochemistry and Molecular Biology / Cancer Center (5/22/2018)
    Our earlier studies have established the role of 12/15-lipoxygenase (LO) in mediating the inflammatory reaction in diabetic retinopathy. However, the exact mechanism is still unclear. The goal of the current study was to identify the potential role of endoplasmic reticulum (ER) stress as a major cellular stress response in the 12/15-LO-induced retinal changes in diabetic retinopathy. We used in vivo and in vitro approaches. For in vivo studies, experimental diabetes was induced in wild-type (WT) mice and 12/15-Lo (also known as Alox15) knockout mice (12/15-Lo−/−); ER stress was then evaluated after 12-14 weeks of diabetes. We also tested the effect of intravitreal injection of 12-hydroxyeicosatetraenoic acid (HETE) on retinal ER stress in WT mice and in mice lacking the catalytic subunit of NADPH oxidase, encoded by Nox2 (also known as Cybb) (Nox2−/− mice). In vitro studies were performed using human retinal endothelial cells (HRECs) treated with 15-HETE (0.1 µmol/l) or vehicle, with or without ER stress or NADPH oxidase inhibitors. This was followed by evaluation of ER stress response, NADPH oxidase expression/activity and the levels of phosphorylated vascular endothelial growth factor receptor-2 (p-VEGFR2) by western blotting and immunoprecipitation assays. Moreover, real-time imaging of intracellular calcium (Ca2+) release in HRECs treated with or without 15-HETE was performed using confocal microscopy. Deletion of 12/15-Lo significantly attenuated diabetes-induced ER stress in mouse retina. In vitro, 15-HETE upregulated ER stress markers such as phosphorylated RNA-dependent protein kinase-like ER-regulated kinase (p-PERK), activating transcription factor 6 (ATF6) and protein disulfide isomerase (PDI) in HRECs. Inhibition of ER stress reduced 15-HETE-induced-leukocyte adhesion, VEGFR2 phosphorylation and NADPH oxidase expression/activity. However, inhibition of NADPH oxidase or deletion of Nox2 had no effect on ER stress induced by the 12/15-LO-derived metabolites both in vitro and in vivo. We also found that 15-HETE increases the intracellular calcium in HRECs. ER stress contributes to 12/15-LO-induced retinal inflammation in diabetic retinopathy via activation of NADPH oxidase and VEGFR2. Perturbation of calcium homeostasis in the retina might also play a role in linking 12/15-LO to retinal ER stress and subsequent microvascular dysfunction in diabetic retinopathy.
  • NLRP3 Inflammasome-Mediated Uncoupling of Hippocampal Vasoneuronal Communications in Diabetes: Relevance to Cognitive Impairment and Stroke

    Ward, Rebecca; Department of Neuroscience and Regenerative Medicine (5/22/2018)
    Diabetes is a prevalent chronic disease that affects over 29 million individuals in the United States and 422 million people worldwide as of 2017. Given the high mortality and morbidity associated with diabetes due to its complications including retinopathy, chronic kidney disease, peripheral neuropathy, heart disease and stroke, this increase in incidence of diabetes creates many clinical, social and economic problems. A silent, but unrecognized complication of diabetes is cognitive impairment, which ranges from mild cognitive impairment to dementia. The increased risk and incidence of stroke amplifies these cognitive deficits. The objectives of this dissertation were to 1) determine the role and mechanism(s) by which diabetes worsens cognitive decline and 2) determine the extent and mechanism by which NLRP3 activation contributes to poor cognitive function after stroke in diabetes. To investigate these objectives, feeding rats a high fat diet and administering a low dose of streptozotocin was used as a clinically relevant diet-enhanced model of diabetes. Stroke was induced through either transient MCAO (60 or 90 min) or embolic MCAO. Embolic stroke caused more severe hippocampal neurovascular injury, microglial activation and cognitive decline in diabetes as compared to stroke induced by a shorter 60 min suture occlusion of the MCA. Diabetic females were more sensitive to ischemic injury than males. Furthermore, hippocampal vascularization patterns at baseline and after ischemic injury differed in males and females and despite these sex differences in the extent and patterns of hippocampal neurovascular injury, diabetes worsened cognitive outcomes in both sexes. Collectively, these first studies provide a preclinical foundation for future studies addressing cognitive impairment in diabetes in both sexes. NLRP3 inflammasome, which cleaves IL-1β and IL-18 into their active forms, was upregulated in diabetes and amplified following ischemia. Inhibition of the NLRP3 inflammasome with MCC950, a specific small molecule inhibitor of NLRP3 activation, improved post-stroke cognition, reduced hippocampal cell death, was associated with less leaky vasculature, and blunted chronic inflammation in the hippocampus after 90-min MCAO. MCC950 did not seem to provide neuroprotection to the neuron through the mBDNF, but did reduce cell death after hypoxia/reoxygenation in vitro. These results are the first to provide essential data showing that MCC950 has the potential to become a therapeutic agent to prevent neurovascular remodeling and worsened cognitive decline in diabetic patients following stroke. Collectively, this work may provide a piece of the puzzle explaining how diabetes leads to cognitive impairment and worsens outcome following acute ischemic injury, and it provides a potential therapeutic target to treat cognitive impairment after stroke, especially in diabetic patients.

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