Coronin 1A facilitates calcium mobilization and promotes astrocyte reactivity in HIV-1 neuropathogenesis

BackgroundIn most neurodegenerative disorders, including neuroAIDS, reactive astrocytes are detrimental to the neuronal population. Calcium and its downstream regulators play a central role in mediating astrocyte reactivity. Coronin 1A, an actin binding protein, majorly reported in hematopoietic cells, regulates cell activity in a calcium-dependent manner, but its role in astrocyte physiology and reactivity is largely unknown. We explored the roles of Coronin 1A in astrocyte physiology and its involvement in facilitating astrocyte reactivity. MethodsCoronin 1A expression was assessed in astrocytes and human brain autopsy sections using western blotting, immunocytochemistry, and immunohistochemistry. siRNA-mediated downregulation was performed to assess its loss of function. To assess the cell activity, live-cell calcium imaging was performed on ATP-stimulated astrocytes using a confocal microscope. HIV-1 Tat B expression vector was used to induce astrocyte reactivity, after which gene and protein expressions were assessed using qPCR and western blotting; cytokine release was measured using flow cytometry and glutamate release was assessed using enzymatic activity. TUNEL assay was performed on neurons treated with the astrocyte-conditioned media. Small RNA-sequencing and qPCR assays were performed to list miRNAs differentially regulated as a result of HIV-1 Tat transfection. Transfection with mimic and inhibitor against selected miRNA and luciferase assay was performed to confirm the miRNA regulation.ResultsWe report Coronin 1A expression in human primary astrocytes and autopsy brain sections, and that it plays activity-dependent roles by facilitating Calcium mobilization from the intracellular stores. HIV-1 Tat, a potent neurotoxicant that turns astrocytes reactive, augments Coronin 1A expression, apart from affecting GFAP and pro-inflammatory molecules. Also, the autopsy brain tissue of HIV-1 infected individuals has higher Coronin 1A expression. Downregulation of Coronin 1A attenuated the HIV-1 Tat-induced deleterious effects of reactive astrocytes, measured as upregulated GFAP expression, enhanced release of IL-6, and Glutamate and hence reduced astrocyte-mediated neuroinflammation. Our findings also suggest that out of a pool of dysregulated miRNAs studied by us, hsa-miR-92b-5p regulates Coronin 1A expression under the effect of HIV-1 Tat. ConclusionThese findings highlight the novel roles of Coronin 1A in regulating astrocyte activity in stimulated conditions and astrocyte reactivity observed in HIV-1 neuropathogenesis.