p62 Binding to Protein Kinase C Regulates HIV-1 gp120 V3 Loop Induced Microglial Inflammation

The main pathogenic mechanism of HIV-associated neurocognitive disorders (HAND) is neuronal apoptosis induced by inflammatory mediators, in which microglial inflammation plays a crucial role. However, the exact pathogenic mechanism remains unclear. Previous studies have shown that the HIV-1 gp120 V3 loop can trigger inflammation in CHME-5 microglia. p62 is a post-translational modified multidomain protein that is involved in the regulation of autophagy and is closely related to neuroinflammation. In this study, we found that p62 knockout down-regulated the expression of MCP-1, IL-6 and COX-2, and improved the inflammation of HIV-1 gp120 V3 loop induced microglia, while overexpression of p62 up-regulated the expression of MCP-1, IL-6 and COX-2, and promoted the inflammation of microglia. In addition, protein kinase C (PKC) knockout down-regulated the expression of MCP-1, IL-6 and COX-2 and inhibited the activation of IKK/ NF-κ B pathway, while tumor necrosis factor receptor-associated factor 6 (TRAF6) knockout had no significant effect on the expression of MCP-1, IL-6 and COX-2. Co-immunoprecipitation showed that p62 was bound and interacted with PKC. Inhibition of IKK/ NF-κ B pathway can down-regulate the expression of MCP-1, IL-6 and COX-2, and improve the inflammatory response of microglia. Our research further found that inhibition of IKK/ NF-κ B can decrease the expression of Caspase-3 and reduce the apoptosis of neurons in the co-culture of CHME-5 microglia and primary mouse neurons. The results of this study suggest that HIV-1 gp120 V3 loop induced CHME-5 microglial inflammation may be activated by the direct binding of p62 and PKC through the IKK/ NF-κ B signaling pathway, and these findings provide an important reference for the prevention and treatment of HAND.