Post-Transcriptional Regulation of Astrocyte-Tissue Inhibitor Metalloproteinase-1 (TIMP-1) in HAND

Purpose (a): HIV-1 can lead to several central nervous system impairments together termed HIV-1-associated neurocognitive disorders (HAND). In acute versus chronic neuroinflammation, differential regulation of Tissue Inhibitor of Metalloproteinase-1 (TIMP-1) is relevant to HAND neuropathogenesis. However, the underlying mechanisms are still being uncovered. In our study, we investigated the post-transcriptional regulation of TIMP-1 3’UTR via miRNAs. Method (b): Microarray analysis was used to analyze miRNA changes in IL-1β-activated astrocytes. To investigate miRNA-mediated TIMP-1 3’UTR post-transcriptional regulation, TIMP-1 3’UTR and specific miRNA overexpression constructs were used. Primary human astrocytes were nucleofected with TIMP-1 3’UTR and Pmir 146b/Pmir 155, and treated with IL-1b 24 h post-transfection. Firefly luciferase activity and astrocyte TIMP-1 levels were analyzed in parallel experiments 24 and 72 hours after IL-1β treatment. Result (c): Microarray analysis showed an increase in 12 miRNAs and decrease in 4 miRNAs. Seven of those were further confirmed by RT-PCR. The most consistent increase was observed in miRNA 155 and miRNA 146b. Overexpression of miRNA 155 and miRNA 146b in IL-1β-activated astrocytes decreased both luciferase activity and endogenous TIMP-1 levels. Conclusion (d): In summary, our preliminary studies suggest that astrocyte-TIMP-1 may be regulated post-transcriptionally by miRNAs (146b and 155) during HAND.