HIV-1 enters the CNS soon after initial systemic infection. HIV-1 can induce a wide range of neurological deficits, collectively known as HIV-1-associated neurocognitive disorders (HAND). Mature neurons are not infected by HIV-1; instead, infected and/or activated glial cells release various viral and cellular factors that induce direct and/or indirect neuronal toxicity, leading to HAND. Injection drug abuse is a significant risk factor for HIV-infection, and opiate drug abusers show increased HIV-neuropathology, even with anti-retroviral treatments. Our previous work has largely modeled HIV-neuropathology using the individual viral proteins Tat or gp120, with murine striatal neurons as targets. To model disease processes more closely, the current study uses supernatant from HIV-1-infected cells. Supernatant from HIV-1SF162 (R5-tropic)-infected differentiated-U937 cells (HIV+sup) was collected and p24 level was measured by ELISA to assess the infection. We assessed HIV+sup effects on neuronal survival and neurite growth/pruning with or without concurrent exposure to morphine, an opiate that preferentially acts through µ-opioid receptors. Effects of HIV+sup ± morphine were assessed on neuronal populations, and also by time-lapse imaging of individual cells. HIV+sup caused dose-dependent toxicity over a range of p24 levels (10-500 pg/ml). Significant interactions occurred with morphine at lower p24 levels (10 and 25 pg/ml). In the presence of glia, selective neurotoxic measures were significantly enhanced and interactions with morphine were also augmented. Importantly, the arrest of neurite growth that occurred with exposure to HIV+sup was reversible unless neurons were continuously exposed to morphine. Thus, while reducing HIV-infection levels may be protective, ongoing exposure to opiates may limit recovery. During early stage of HIV-infection R5-tropic viruses are predominant, but during later stages of disease X4-tropic viruses are more predominant; co-receptor usage switch from CCR5 to CXCR4 is crucial in disease progression to AIDS. Some previous studies have shown that drugs of abuse interact with virus or viral proteins in strain/tropism-dependent manner. Therefore, we also assessed neurotoxic effects and interactions with opiates by supernatant from HIV-1LAI (X4-tropic)-infected H9 cells. Neurotoxic effects and the interactions with opiates of HIV-1LAI-supernatant are quantitatively similar to that of HIV-1SF162. Surprisingly, the cytokine/chemokine release profile of HIV-1LAI-infected H9 cells is similar to that of HIV-1SF162-infected U937 cells. Only in the presence of glia, HIV-1LAI virion induced neurotoxic effects, but no interactions with morphine were seen. Also our studies have shown that HIV-1LAI virions are slightly more neurotoxic than HIV-1SF162. Altogether, largely our results suggest that HIV+sup mediated neurotoxicity and the interactions with opiates are majorly attributed to cytotoxic factors released from infected and activated cells instead of viral strain specific factors. Although there is a correlation between opiate drug abuse and progression of HAND, the mechanisms that underlie interactions between HIV-1 and opiates remain obscure. Previous studies have shown that HIV-1 induces neurotoxic effects through abnormal activation of GSK3β. Interestingly, expression of GSK3β has shown to be elevated in the brains of young opiate abusers suggesting that GSK3β is also linked to neuropathology seen with opiate abusing patients. Thus, we hypothesized that GSK3β activation is a point of convergence for HIV- and opiate-mediated interactive neurotoxic effects. Cultures of striatal neurons were treated with HIV+sup (R5-tropic), in the presence or absence of morphine and GSK3β inhibitors. Our results show that multiple GSK3β inhibitors significantly reduce HIV-1-mediated neurotoxic outcomes, and also negate interactions with morphine that result in cell death. This suggests that GSK3β-activation is an important point of convergence and a potential therapeutic target for HIV- and opiate-mediated neurocognitive deficits.

PART1, TITLE: A p53-inducible long non-coding RNA PICART1 mediating cancer cell proliferation and migration. Long non-coding RNAs (lncRNAs) function in the development and progression of cancer, but only a small portion of lncRNAs are characterized thus far. A novel lncRNA transcript with 2.53 kb in length was identified by a transcriptome sequencing analysis, named p53-inducible cancer-associated RNA transcript 1 (PICART1). This PICART1 is upregulated by p53 through a p53-binding site at -1808 to -1783bp. In breast and colorectal cancer cells and tissues, PICART1 expression was decreased. Ectopic expression of the PICART1 suppressed growth, proliferation, migration, and invasion of MCF7, MDA-MB-231 and HCT116 cells whereas silencing of PICART1 stimulated the cell growth and migration. In these cells, the expression of PICART1 lowered down the levels of p-AKT (Thr308 & Ser473) and p-GSK3β (Ser9), and accordingly, β-catenin, cyclin D1 and c-Myc expression were decreased, but p21cip1/Waf1 expression was increased. Together these data suggest that PICART1 is a novel p53-inducible tumor suppressor lncRNA, functioning through the AKT/GSK3β/β-catenin signaling cascade. PART2, TITLE: The novel long non-coding RNA PANCR is a tumor suppressor gene in breast cancer. Long non-coding RNAs (lncRNAs) function as oncogenes or tumor suppressors in development and progression of cancer. Chromosome 16q22.1 region is frequently deleted in breast cancer, which may contribute to breast carcinogenesis by inactivation of tumor suppressor genes. This study characterized a new lncRNA tumor suppressor, named p53 activating non-coding RNA (PANCR), located in this Chromosome 16q22.1 region. This PANCR lncRNA consists of 1.5kb in length. Our data showed that PANCR was downregulated in breast cancer tissues and cell lines. In the breast cancer cell lines, PANCR expression appeared reversely correlated with cell malignancy, and in breast cancer tissues, PANCR was downregulated over 2 times in 31 (62.0%) of 50 cases when compared to adjacent normal breast tissues. In breast cancer cells MCF7 cells, ectopic expression of PANCR suppressed cell proliferation in culture, but in contrast, shRNA–mediated silencing of PANCR promoted cell growth and proliferation.

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abstract: In somatic cells, the mitotic spindle apparatus is centrosomal and several isoforms of Protein Kinase C (PKC) have been associated with the mitotic spindle, but their role in stabilizing the mitotic spindle is unclear. Other protein kinases such as, Glycogen Synthase Kinase 3â (GSK3â) also have been shown to be associated with the mitotic spindle. In the study in chapter 2, we show the enrichment of active (phosphorylated) PKCæ at the centrosomal region of the spindle apparatus in metaphase stage of 3T3 cells. In order to understand whether the two kinases, PKC and GSK3â are associated with the mitotic spindle, first, the co-localization and close molecular proximity of PKC isoforms with GSK3â was studied in metaphase cells. Second, the involvement of inactive GSK3â in maintaining an intact mitotic spindle was shown. Third, this study showed that addition of a phospho-PKCæ specific inhibitor to cells can disrupt the mitotic spindle microtubules. The mitotic spindle at metaphase in mouse fibroblasts appears to be maintained by PKCæ acting through GSK3â. The MAPK pathway has been implicated in various functions related to cell cycle regulation. MAPKK (MEK) is part of this pathway and the extracellular regulated kinase (ERK) is its known downstream target. GSK3â and PKCæ also have been implicated in cell cycle regulation. In the study in chapter 3, we tested the effects of inhibiting MEK on the activities of ERK, GSK3â, PKCæ, and á-tubulin. Results from this study indicate that inhibition of MEK did not inhibit GSK3â and PKCæ enrichment at the centrosomes. However, the mitotic spindle showed a reduction in the pixel intensity of microtubules and also a reduction in the number of cells in each of the M-phase stages. A peptide activation inhibitor of ERK was also used. Our results indicated a decrease in mitotic spindle microtubules and an absence of cells in most of the M-phase stages. GSK3â and PKCæ enrichment were however not inhibited at the centrosomes. Taken together, the kinases GSK3â and PKCæ may not function as a part of the MAPK pathway to regulate the mitotic spindle. / Dissertation/Thesis / Ph.D. Molecular and Cellular Biology 2012

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Indiana University-Purdue University Indianapolis (IUPUI) / Posttraumatic epilepsy, the development of temporal lobe epilepsy (TLE) following traumatic brain injury, accounts for 20% of symptomatic epilepsy. Reorganization of mossy fibers within the hippocampus is a common pathological finding of TLE. Normal mossy fibers project into the CA3 region of the hippocampus where they form synapses with pyramidal cells. During TLE, mossy fibers are observed to innervate the inner molecular layer where they synapse onto the dendrites of other dentate granule cells, leading to the formation of recurrent excitatory circuits. To date, the molecular mechanisms contributing to mossy fiber sprouting are relatively unknown. Recent focus has centered on the involvement of tropomycin-related kinase receptor B (TrkB), which culminates in glycogen synthase kinase 3β (GSK3β) inactivation. As the neurite outgrowth promoting collapsin response mediator protein 2 (CRMP2) is rendered inactive by GSK3β phosphorylation, events leading to inactivation of GSK3β should therefore increase CRMP2 activity. To determine the involvement of CRMP2 in mossy fiber sprouting, I developed a novel tool ((S)-LCM) for selectively targeting the ability of CRMP2 to enhance tubulin polymerization. Using (S)-LCM, it was demonstrated that increased neurite outgrowth following GSK3β inactivation is CRMP2 dependent. Importantly, TBI led to a decrease in GSK3β-phosphorylated CRMP2 within 24 hours which was secondary to the inactivation of GSK3β. The loss of GSK3β-phosphorylated CRMP2 was maintained even at 4 weeks post-injury, despite the transience of GSK3β-inactivation. Based on previous work, it was hypothesized that activity-dependent mechanisms may be responsible for the sustained loss of CRMP2 phosphorylation. Activity-dependent regulation of GSK3β-phosphorylated CRMP2 levels was observed that was attributed to a loss of priming by cyclin dependent kinase 5 (CDK5), which is required for subsequent phosphorylation by GSK3β. It was confirmed that the loss of GSK3β-phosphorylated CRMP2 at 4 weeks post-injury was likely due to decreased phosphorylation by CDK5. As TBI resulted in a sustained increase in CRMP2 activity, I attempted to prevent mossy fiber sprouting by targeting CRMP2 in vivo following TBI. While (S)-LCM treatment dramatically reduced mossy fiber sprouting following TBI, it did not differ significantly from vehicle-treated animals. Therefore, the necessity of CRMP2 in mossy fiber sprouting following TBI remains unknown.