Browsing by Subject "HIV-1 Tat"
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Item HIV-1 TAT EXPRESSION ALTERS HUMAN ASTROCYTE INFLAMMATORY BIOMARKER PROFILES AND GLUTAMATE METABOLISM(2014-03) Joshi, Chaitanya R.; Ghorpade, AnujaPurpose (a): More than 50% of the human immunodeficiency virus type 1 (HIV-1) infected individuals exhibit some form of HIV-associated neurocognitive disorders (HAND). Several studies reported that HIV-1 transactivator of transcription (Tat) protein was associated with HAND pathophysiology. HIV-1 Tat induces apoptosis and dysregulates cytokine/chemokine profiles leading to neurotoxicity. Previous studies have studied the in vivo HIV-1 Tat regulation using transgenic animal models. Although animal models have helped determine the in vivo disease pathology, application of in vitro neural cell models will be critical to decipher cellular and molecular mechanisms associated with HAND. Here, we report an in vitro model system developed by transfecting human astrocytes with a full-length (101 AA) HIV-1 Tat protein expressing plasmid (pTat). HIV-1 Tat expressing in vitro system was used to evaluate HIV-1 Tat regulation of astrocyte inflammatory responses and altered neuroprotective function i.e. glutamate uptake from synapse. Methods (b): Primary human astrocytes were transfected with pTat by nucleofection and HIV-1 Tat expression was evaluated by immunocytochemistry. Effects of HIV-1 Tat on cell viability and replication were determined with metabolic activity and cell proliferation assays. Proinflammatory cytokines and chemokines were assayed using ELISAs. HIV-1 Tat regulation of glutamate clearing ability of astrocytes was determined using a modified amplex red glutamic acid/glutamate oxidase assay. Additionally, mRNA and protein expression of excitatory amino acid transporter-2 (EAAT-2), the major glutamate transporter in astrocytes, was measured by RT-PCR and western blot analysis respectively. Results (c): The immunostaining confirmed HIV-1 Tat expression in transfected astrocytes, while glial fibrillary acidic protein (GFAP) staining indicated morphological alterations. The pTat transfection did not significantly change cell metabolism as compared to controls. However, HIV-1 Tat expression altered chemokine and cytokine levels; specifically HIV-1 Tat increased CCL2 levels significantly (P. Conclusions (d): HIV-1 Tat expression upregulated inflammatory biomarkers and altered glutamate clearing ability of astrocytes, implicating a direct role for astrocyte-expressed HIV-1 Tat in HAND neuropathogenesis.Item Long-term HIV-1 Tat Expression in the Brain Led to Neurobehavioral, Pathological, and Epigenetic Changes Reminiscent of Accelerated Aging(International Society on Aging and Disease, 2020-02-01) Zhao, Xiaojie; Fan, Yan; Vann, Philip H.; Wong, Jessica M.; Sumien, Nathalie; He, Johnny J.HIV infects the central nervous system and causes HIV/neuroAIDS, which is predominantly manifested in the form of mild cognitive and motor disorder in the era of combination antiretroviral therapy. HIV Tat protein is known to be a major pathogenic factor for HIV/neuroAIDS through a myriad of direct and indirect mechanisms. However, most, if not all of studies involve short-time exposure of recombinant Tat protein in vitro or short-term Tat expression in vivo. In this study, we took advantage of the doxycycline-inducible brain-specific HIV-1 Tat transgenic mouse model, fed the animals for 12 months, and assessed behavioral, pathological, and epigenetic changes in these mice. Long-term Tat expression led to poorer short-and long-term memory, lower locomotor activity and impaired coordination and balance ability, increased astrocyte activation and compromised neuronal integrity, and decreased global genomic DNA methylation. There were sex- and brain region-dependent differences in behaviors, pathologies, and epigenetic changes resulting from long-term Tat expression. All these changes are reminiscent of accelerated aging, raising the possibility that HIV Tat contributes, at least in part, to HIV infection-associated accelerated aging in HIV-infected individuals. These findings also suggest another utility of this model for HIV infection-associated accelerated aging studies.