MicroRNAs upregulated during HIV infection target peroxisome biogenesis factors: Implications for virus biology, disease mechanisms and neuropathology

HIV-associated neurocognitive disorders (HAND) represent a spectrum neurological syndrome that affects up to 25% of patients with HIV/AIDS. Multiple pathogenic mechanisms contribute to the development of HAND symptoms including chronic neuroinflammation and neurodegeneration. Among the factors linked to development of HAND is altered expression of host cell microRNAs (miRNAs) in brain. Here, we examined brain miRNA profiles among HIV/AIDS patients with and without HAND. Our analyses revealed differential expression of 17 miRNAs in brain tissue from HAND patients. A subset of the upregulated miRNAs (miR-500a-5p, miR-34c-3p, miR-93-3p and miR-381-3p), are predicted to target peroxisome biogenesis factors (PEX2, PEX7, PEX11B and PEX13). Expression of these miRNAs in transfected cells significantly decreased levels of peroxisomal proteins and concomitantly decreased peroxisome numbers or affected their morphology. The levels of miR-500a-5p, miR-34c-3p, miR-93-3p and miR-381-3p were not only elevated in the brains of HAND patients, but were also upregulated during HIV infection of primary macrophages. Moreover, concomitant loss of peroxisomal proteins was observed in HIV-infected macrophages as well as in brain tissue from HIV-infected patients. HIV-induced loss of peroxisomes was abrogated by blocking the functions of the upregulated miRNAs. Overall, these findings point to previously unrecognized miRNA expression patterns in the brains of HIV patients. Targeting peroxisomes by up-regulating miRNAs that repress peroxisome biogenesis factors may represent a novel mechanism by which HIV-1 subverts innate immune responses and/or causes neurocognitive dysfunction.

Host cells employ a myriad of antiviral defense systems but most viruses have developed effective countermeasures. Viruses such as HIV that cause lifelong infections are particularly successful in subverting the host antiviral response. While mitochondria have long been known to be critical hubs for antiviral signaling, it has only recently become apparent that peroxisomes are also important for this process. Peroxisomes are small and numerous structures that are best known for their roles in lipid metabolism. New evidence suggests that pathogenic viruses such as West Nile and Dengue viruses block the production of peroxisomes by sequestering and degradation a critical biogenesis factor. In the present study, we report that HIV significantly reduces the number of peroxisomes in infected cells via a completely novel mechanism. Specifically, HIV-infected cells express high levels of microRNAs that inhibit production of proteins required for peroxisome formation. Interestingly, levels of these microRNAs were elevated in the brains of patients with HIV-associated neurocognitive disorders. Thus, as well as affecting antiviral signaling, loss of peroxisomes during HIV infection may contribute to development of neurological disorders. Understanding how pathogenic viruses affect peroxisome biogenesis and cognate antiviral signaling may ultimately lead to novel therapeutic avenues and prevention of long-term sequelae.