Cervical cancer is the fourth most frequent cancer in women with an estimated 570,000 new cases globally in 2018. Treatment of advanced cervical cancer is often unsuccessful leading to high cancer-related mortality rates, especially in under-resourced countries. Recently, a possible role for the cell surface glycoprotein CD24 in host cell specificity of Zika virus was reported. As an extension of this work, Zika viruses have been proposed as oncolytic therapy for the treatment of neuroblastoma and other CD24 positive tumors. To determine the permissiveness of cervical cancer cells to Zika virus infection and its association with CD24, we assessed cytopathic effect (CPE) induced by Zika virus in cervical cancer cell lines (HeLa, SiHa and CaSki) by light microscopy and by cytotoxicity assay. Cervical cancer cells were susceptible to Zika virus-induced apoptosis. Upon infection, the morphology of cervical cancer cells changed, exhibiting Zika virus-induced CPE. Cervical cancer cell expression of viral non-structural protein 1 (NS1) after infection demonstrated viral protein translation. Quantitative plaque assays demonstrated the production of competent virions. Because CD24 expression was found to be important for Zika virus infection in neuroblastoma cells, CD24 expression was assessed in cervical cancer cells. Cervical cancer cells expressed low but measurable levels of CD24 mRNA and protein. siRNA-mediated knockdown of CD24 resulted in reduced NS1 expression and reduced levels of virus-induced apoptosis. Taken together our data suggest a possible role for CD24 in Zika virus-induced apoptosis in cervical cancer cells. Zika virus-induced apoptosis of cultured cervical cancer cells presents the possibility for the use of Zika virus as a potential oncolytic therapy for cervical cancer.

Both genetic pre-disposition and potential environmental triggers are shared between Rheumatoid arthritis (RA) and Crohn's disease (CD). We hypothesized that single nucleotide polymorphisms (SNPs) in the negative T-cell regulators Protein Tyrosine Phosphatase Nonreceptor type 2 and 22 (PTPN2/22) lead to a dysregulated immune response as seen in RA and CD. To test the hypothesis, peripheral leukocytes samples from 204 consented subjects were TaqMan genotyped for 9 SNPs in PTPN2/22. The SNPs effect on PTPN2/22 and IFN-y expression was determined using RT-PCR. Blood samples were analyzed for the Mycobacterium avium subspecies paratuberculosis (MAP) IS900 gene by nPCR. T-cell proliferation and response to phytohematoagglutonin (PHA) mitogen and MAP cell lysate were determined by BrdU proliferation assay. Out of 9 SNPs, SNP alleles of PTPN2:rs478582 occurred in 79% RA compared to 60% control (p-values ≤ 0.05). SNP alleles of PTPN22:rs2476601 occurred in 29% RA compared to 6% control (p-values ≤ 0.05). For the haplotype combination of PTPN2:rs478582/PTPN22rs2476601, 21.4% RA had both SNPs (C-A) compared to 2.4% control (p-values ≤ 0.05). PTPN2/22 expression in RA was decreased by an average of 1.2 fold. PTPN2:rs478582 upregulated IFN-y in RA by an average of 1.5 fold. Combined PTPN2:rs478582/PTPN22:rs2476601 increased T-cell proliferation by an average of 2.7 fold when treated with PHA. MAP DNA was detected in 34% RA compared to 8% controls (p-values ≤ 0.05), where samples with PTPN2:rs478582 and/or PTPN22:rs2476601 were more MAP positive. PTPN2:rs478582/PTPN22:rs2476601 together with MAP infection significantly increased T-cell response and IFN-y expression in RA samples. The same experimental approach was followed on blood samples from CD patients. Both PTPN2:rs478582/PTPN22:rs2476601 affected PTPN2/22 and IFN-y expression along with T-cell proliferation significantly more than in RA. MAP DNA was detected in 64% of CD. This is the first study to report the correlation between SNPs in PTPN2/22, IFN-y expression and MAP in autoimmune disease.

Cytolethal distending toxin (CDT) is a virulence factor produced by many Gram-negative bacteria, including Haemophilus ducreyi. This fastidious pathogen is the causative agent of genital cancroid. CDT is a heterotrimeric toxin with an AB2 structure consisting of a cell-binding "B" domain (CdtA + CdtC) and a catalytic "A" domain (CdtB) that has DNase activity. This toxin assembles in the bacterial periplasm that lacks ATP and is secreted into the extracellular environment. After cell binding, CDT is internalized by endocytosis and travels through the endosomes and Golgi before arriving in the endoplasmic reticulum (ER). CdtA is lost from the holotoxin before reaching the Golgi, and CdtB separates from CdtC in the ER. CdtB is then transported into the nucleus, inducing cell cycle arrest and apoptosis. Using disassembly of the AB5 pertussis toxin as a model, we explore that ATP, which is present in the ER lumen but not in the endosomes or Golgi, will cause dissociation of the CdtB/CdtC heterodimer. We have cloned and purified the three individual subunits of the H. ducreyi CDT. When combined, the subunits form a lethal holotoxin. Examining the individual toxin subunits, only CdtB binds with ATP but does not function as an ATPase. CdtB's binding to ATP also does not cause global changes to its secondary structure. After isolating the CdtB/CdtC heterodimer, we have shown the addition of ATP causes CdtC to dissociate from CdtB. The work presented in this Thesis provides a molecular basis for why the CdtB/CdtC heterodimer disassembles after reaching the ER and confirms the novel two-stage disassembly mechanism for CDT, a first in the AB toxin field.

Selenium is a vital micronutrient in many organisms. While traces are required for survival, excess amounts are toxic; thus, selenium can be regarded as a biological "double-edged sword". Selenium is chemically similar to the essential element sulfur, but curiously, evolution has selected the former over the latter for a subset of oxidoreductases. Enzymes involved in sulfur metabolism are less discriminate in terms of preventing selenium incorporation; however, its specific incorporation into selenoproteins reveals a highly discriminate process that is not completely understood. In this work, we add knowledge to the mechanism for selenium-over-sulfur specificity in hopes of further understanding the controlled regulation of selenium trafficking and the prevention of its toxicity. We have identified SclA, a selenocysteine lyase in the nosocomial pathogen, Enterococcus faecalis, and characterized its enzymatic activity and specificity for L-selenocysteine over L-cysteine. Human selenocysteine lyase contains a residue, D146, which plays a significant role in determining its specificity. A D146K mutation eliminated this trait, allowing non-specific L-cysteine degradation. Using computational biology, we identified an orthologous residue in SclA, H100, and generated mutant enzymes with site-directed mutagenesis. The proteins were overexpressed, purified, and characterized for their biochemical properties. All mutants exhibited varying levels of activity towards L-selenocysteine, hinting at a catalytic role for H100. Additionally, L-cysteine acted as a competitive inhibitor towards all enzymes with higher affinity than L-selenocysteine. Finally, our experiments revealed that SclA possessed extremely poor cysteine desulfurase activity with each mutation exhibiting subtle changes in turnover. Our findings offer key insight into the molecular mechanisms behind selenium-over-sulfur specificity and may further elucidate the role of selenocysteine lyases in vivo.

Prostate cancer is the most common cancer in men in the western world. Although early stage prostate cancer is treatable late stage, more specifically, metastatic and drug resistant prostate cancers are mostly incurable. The failure of current treatments obligates the research community to explore novel areas in prostate cancer biology and find better therapeutic targets. Emerging evidences show that non-coding RNAs specifically long non-coding RNAs (lncRNAs) play regulatory roles in various cellular processes and are frequently dysregulated in cancer including prostate cancer. These aberrantly expressed lncRNAs mostly with unexplored genetic information may drive cancer progression. Previous studies done in our laboratory showed a tumor suppressor role of a cluster of small non-coding RNAs or microRNA (miRNA) miR-17-92a in PC-3 prostate cancer cells. To learn the underlying mechanism, transcriptome analysis with or without expression of miR-17-92a was conducted in our laboratory. RNA-sequencing data analysis identified reduced expression of a set of lncRNAs and oncogenes, and up regulation of several tumor suppressor genes upon expression of miR-17-92a cluster miRNAs. One of the down regulated intergenic lncRNAs, PAINT (Prostate Cancer Associated Intergenic Non-coding Transcript) (LINC00888), was selected for determining its functional role in prostate cancer. TCGA and GEO profiles analyses revealed up regulation of PAINT in prostate tumors with higher Gleason Scores, in highly aggressive metastatic prostate cancer cell lines, and upon androgen deprivation therapy of prostate cancer cells. This observation was supported by our studies on expression analysis of PAINT in prostate tumor tissues using RNA in-situ hybridization in tissue microarrays (TMA) containing tissues from different stages of prostate cancer and normal prostate tissues, which showed higher expression of PAINT in prostate cancer tissues compared to normal tissues. Furthermore, late stage (stage III and stage IV) prostate tumors showed significant overexpression of PAINT compared to early stage (stage II) prostate cancer tissues. We examined the functional relevance of PAINT in promoting tumor progression next using different prostate cancer cell lines. Silencing of PAINT using siRNAs showed decreased cell proliferation, reduced S-phase progression and activation of pro-apoptotic proteins PARP and Caspase-3. Silencing of PAINT also showed decreased cell migration and increased expression of the epithelial marker, E-cadherin while reduced expression of mesenchymal markers Slug and Vimentin. Ectopic expression of PAINT reversed the effects observed upon silencing of PAINT. Increased cell proliferation, cell cycle progression and cell migration were noted in prostate cancer cells overexpressing PAINT. Additionally, cancer promoting phenotype such as larger colony formation and higher expression of mesenchymal marker Slug, was detected upon overexpression of PAINT. Our study also determined the therapeutic benefit of inhibition of expression showing an increased sensitivity of metastatic prostate cancer cells to the chemotherapeutic agent docetaxel (DTX) and selective Aurora kinase inhibitor VX-680. Taken together, our study establishes an oncogenic function of PAINT, its clinical relevance as a marker for advanced stage prostate cancer and its potential as a therapeutic target for metastatic prostate cancer.

Phenylethanolamine N-methyltransferase (Pnmt) is the enzyme that N-methylates norepinephrine to produce the stress hormone/neurotransmitter, epinephrine, which is abundantly expressed in adrenal glands. Developmental studies have also identified Pnmt expression in the embryonic heart and several areas of the brain, including brainstem, cerebellum, and hypothalamus. Thus, we hypothesize that selective ablation of Pnmt+ cells will have detrimental effects on cardiovascular, neuromuscular, and metabolic processes. To uncover the importance of Pnmt+ cells in vivo, we generated a novel Diphtheria Toxin A (DTA) suicide model (Pnmt+/Cre; R26+/DTA) to selectively ablate Pnmt-expressing (Pnmt+) cells in mice. Appearing normal at birth, Pnmt-Cre/DTA mice began to develop apparent cardiovascular, neurological, and metabolic impairments soon thereafter. To measure cardiac function, we performed quantitative echocardiography, electrocardiography (ECG), and blood pressure measurements. Key findings from these assessments indicated decreased left-ventricular performance, slowed atrioventricular conduction, and increased pulse pressure in the Pnmt-Cre/DTA ablation mice. These mice also showed signs of motor control deficits as early as one month, which progressively worsened with age. To assess these effects, we performed standard motor tests including hind-limb clasping, grip strength, and rotarod balance tests. Moreover, we found that the Pnmt-Cre/DTA mice ceased to gain weight shortly after puberty. The motor and metabolic deficits apparent in these animals suggested potential neurological impairments, and we thus undertook immunohistochemical staining experiments to determine the localization of Pnmt+ cells in the brain. Staining revealed Pnmt expression in the Purkinje cells of the cerebellum (motor), paraventricular nucleus of the hypothalamus (metabolic), and surprisingly extensive staining in the cerebral cortex. These results demonstrate that Pnmt+ cell contributions in the brain are much more extensive than previously thought. Overall, this work opens new pathways that will have substantial impacts on our understanding of the roles Pnmt+ cells play in normal development and disorders affecting cardiovascular, motor, and metabolic functions.

Vibrio cholerae is the etiological agent of the severe diarrheal disease cholera. The bacterium is a natural inhabitant of brackish and estuarine waters . To date, only a subset of V. cholerae strains, those belonging to the pandemic group (PG), can cause cholera in humans while the rest (environmental group, EG) cannot cause the disease. Recently, we discovered that V. cholerae PG contains allelic variations in core genes that confer preadaptation to virulence, which we termed Virulence Adaptive Polymorphisms (VAPs). We identified nine core genes that encode potential VAPs, one of which encodes the outer membrane porin U (OmpU). OmpU provides tolerance to bile and acidic pH, resistance to antimicrobials and facilitates biofilm formation. In this study, several alleles of ompU were analyzed to determine whether these VAPs encode different functional properties. We performed multiple phenotypic assays and observed increased survival for strains encoding the PG-like alleles in the presence of bile, organic acid, anionic detergents and the antimicrobial peptide P2. On the other hand, EG-like alleles only showed increased biofilm formation. Interestingly, tests for motility and tolerance of inorganic acid, polymyxin B and protamine sulphate showed no differences in survival for strains encoding either alleles indicating that some of the properties conferred by OmpU are allelic independent. We have also discovered that V. cholerae OmpU shows resistance against Rifamycin, EDTA and Trifluoperazine and interestingly, Rifamycin has been found to be PG-allele dependent. Our findings provide further evidence that genetic variations in core genes lead to the emergence of virulence adaptive traits in pathogenic V. cholerae and can be extrapolated to other bacterial pathogens.

The liver distributes serum triacylglycerol (TAG) via the very low-density lipoprotein (VLDL), and an increase in VLDL production may result in hyperlipidemia. VLDL synthesis consists of lipidation of Apolipoprotein B100 (ApoB) as it is co- translationally translocated across the endoplasmic reticulum (ER) membrane, and this nascent VLDL particle must undergo subsequent maturation and post-translational modification in the Golgi. The ER-to-Golgi trafficking of VLDL represents the rate-limiting step in VLDL secretion and is mediated by the VLDL Transport Vesicle (VTV). Many in vivo studies have indicated that vitamin E (alpha-tocopherol) supplementation protects against atherosclerosis and can reduce hepatic steatosis in nonalcoholic fatty liver disease (NAFLD), but its effects at the molecular level on hepatic lipid metabolism are poorly understood. To investigate the effects of alpha-tocopherol on hepatic VLDL secretion and cellular lipid retention, we performed several experiments in HepG2 (human) and McARH- 7777 (rat) hepatoma cell lines including pulse-chase experiments using 3H-oleic acid (3H- OA), confocal microscopy with BODIPY lipid droplet staining, and an in vitro VTV budding assay. Our results demonstrate a significant reduction of 3H-TAG secretion and ApoB media expression in response to 100 uM alpha-tocopherol, with a corresponding decrease in markers of VTV biogenesis in western blots of whole cell lysates (WCL) and retention of ApoB within the cell, indicating disruption of an early step in VLDL biogenesis. Further evidence indicates an increase in size and lipidation of the VTV and VLDL particle. BODIPY staining as well as 3H-TAG retention in WCLs was also sharply reduced. Overall, these results indicate that alpha-tocopherol reduces VLDL secretion, partially disrupts hepatic VLDL synthesis and VTV biogenesis, increases the lipidation of remaining VLDL particles, and diminishes overall cellular lipid droplet retention.

More than 570,000 new cases of esophageal cancer are estimated to be diagnosed annually worldwide. Risk factors include gender, age, tobacco use and dietary habits leading to tissue injury and ultimately cancer. While prognoses for other cancers have improved, the 5-year survival for patients with esophageal cancer is only 20%. During the repair process, cell proliferation is increased and is associated with inflammation. Slow-cycling lifetime residential stem cells, called quiescent cells, facilitate repair but are thought to accumulate mutations during DNA replication eventually giving rise to cancer. We hypothesize that esophageal stem cells become activated upon injury and are regulated by Transforming Growth Factor beta 1 (TGFβ1), a known regulator of cell proliferation and differentiation. We established an in vitro model of quiescence using normal esophageal epithelial (STR) and oral (OKF6) cells treated with recombinant human TGFβ1. Flow cytometry showed increases in cells arrested in G1/G0 phase of the cell cycle in TGFβ1 treated cells for both cell lines (STR p < 0.01, OKF6 p < 0.05). EdU (5-ethynyl-2'-deoxyuridine) positive recovery cells indicated quiescence in both cell lines (p < 0.01). Analysis of TGFβ1 regulation of putative stem cell markers via western blot and qRT-PCR showed increases in ITGB1, PDPN and K15 as well as XPC, and MeCP2 in treated cells. To apply our in vitro findings, we performed immunohistochemistry staining on tissue microarrays. Proliferation marker Ki67 increased in disease progression from normal to inflammation to hyperplasia (p < 0.001) while TGFβ1 target markers decrease. Our data indicate that the onset of cancer-associated inflammation correlates with the loss of TGF?1 mediated stemness markers and increased basal proliferation suggesting cancer is a stem cell disease.

Cardiovascular diseases cause 17 million deaths annually, which is estimated to increase to 23 million deaths by the year 2030. One of the major risk factors for the pathogenesis of cardiovascular diseases is increased secretion of very-low density lipoproteins (VLDL) by the liver; however, reduced VLDL-secretion causes fatty liver disease. Synthesis and secretion of VLDL by the liver plays an important role in maintaining overall lipoprotein homeostasis. Assembly of VLDL occurs along with the expression of apolipoproteinB-100 (apoB100) and its lipidation at the endoplasmic reticulum (ER) level. Once formed in the ER lumen, the nascent VLDL is transported to the Golgi for its maturation. In the Golgi compartment, the nascent VLDL acquires apolipoproteinAI (apoAI), more triglycerides, and its apoB100 undergoes phosphorylation and glycosylation. These modifications are necessary for VLDL-exit from the trans-Golgi network (TGN) and this step is mediated by post-Golgi VLDL transport vesicle (PG-VTV). The transport of mature VLDL from the TGN to the plasma membrane (PM) is required for its secretion by the liver but remains to be studied. Our group has shown that the nascent VLDL particles do not contain apoAI, however, VLDL acquires apoAI in the cis-Golgi compartment. Interestingly, apoAI comes off the VLDL as soon as VLDL is secreted into the blood. We hypothesised that apoAI plays an important role in post-TGN VLDL trafficking and thus controls VLDL secretion by the liver. To determine the role of apoAI in the formation of PG-VTV and VLDL secretion, we knocked down apoAI in the hepatocytes using apoAI specific siRNA. The deficiency of apoAI did not have any effect on the expression of apoB100 and other apolipoprotein synthesis that are involved in VLDL synthesis; however, VLDL secretion was significantly reduced. Next, we overexpressed apoAI using plasmid with apoAI gene sequence and checked for the effects in VLDL secretion from the hepatocytes. We observed a significant increase in VLDL secretion from apoAI-overexpressing hepatocytes which is consistent with knockdown results. To determine the role of apoAI in post-TGN trafficking of the mature VLDLs, we isolated sub-cellular organelles from apoAI knockout (apoAI KO) and control mice. Subsequently, we performed in vitro PG-VTV budding assays to assess the effect of apoAI silencing on PG-VTV formation from the TGN. Our results strongly suggest that the deficiency of apoAI increases PG-VTV formation (i.e. TGN-exit of mature VLDL) but significantly reduces VLDL-triglyceride secretion from the hepatocytes. We conclude that apoAI controls VLDL secretion by the liver by regulating post-TGN trafficking of mature VLDL.