Role of Hexokinase-1 in the survival of HIV-1-infected macrophages

Abstract

Viruses have developed various strategies to protect infected cells from apoptosis. HIV-1 infected macrophages are long-lived and considered reservoirs for HIV-1. One significant deciding factor between cell survival and cell death is glucose metabolism. We hypothesized that HIV-1 protects infected macrophages from apoptosis in part by modulating the host glycolytic pathway specifically by regulating hexokinase-1 (HK-1) an enzyme that converts glucose to glucose-6-phosphate. Therefore, we analyzed the regulation of HK-1 in HIV-1 infected PBMCs, and in a chronically HIV-1 infected monocyte-like cell line, U1. Our results demonstrate that HIV-1 induces a robust increase in HK-1 expression. Surprisingly, hexokinase enzymatic activity was significantly inhibited in HIV-1 infected PBMCs and in PMA differentiated U1 cells. Interestingly, we observed increased levels of mitochondria-bound HK-1 in PMA induced U1 cells and in the HIV-1 accessory protein, viral protein R (Vpr) transduced U937 cell derived macrophages. Dissociation of HK-1 from mitochondria in U1 cells using a pharmacological agent, clotrimazole (CTZ) induced mitochondrial membrane depolarization and caspase-3/7 mediated apoptosis. Dissociation of HK-1 from mitochondria in Vpr transduced U937 also activated caspase-3/7 activity. These observations indicate that HK-1 plays a non-metabolic role in HIV-1 infected macrophages by binding to mitochondria thereby maintaining mitochondrial integrity. These results suggest that targeting the interaction of HK-1 with the mitochondria to induce apoptosis in persistently infected macrophages may prove beneficial in purging the macrophage HIV reservoir.

Preferential Destruction of Interstitial Macrophages over Alveolar Macrophages as a Cause of Pulmonary Disease in Simian Immunodeficiency Virus–Infected Rhesus Macaques

“…Although not addressed in the present study, it will be important to understand the molecular mechanisms for SIV-induced cell killing of IM but not of AM in the lung tissues to include measurement for determining the level of cell death factors or cell survival factors (e.g. hexokinase-6) in different macrophage subsets as previously described (38). …”

HIV-1 Tat and Cocaine Impair Survival of Cultured Primary Neuronal Cells via a Mitochondrial Pathway

“…Cell pellets were washed, repelleted and the supernatants were removed. Pellets were subjected to differential centrifugation as we have previously described (Sen et al, 2015). Following the isolation procedures, the resulting mitochondrial-enriched pellets were immediately resuspended and lysed in a small volume of TNN lysis buffer (40 mM Tris-HCl pH 7.4, 150 mM NaCl, 1 mM DTT, 1 mM EDTA, 1% NP40, and 1% protease/phosphatase inhibitors cocktail).…”

Emerging Role and Characterization of Immunometabolism: Relevance to HIV Pathogenesis, Serious Non-AIDS Events, and a Cure

“…Increased glucose uptake and glycolytic metabolism provide precursors for HIV biosynthesis, as well as intermediary enzymes that may disengage glycolysis and regulate HIV reactivation (31). Association of hexokinase with the outer mitochondrial membrane of HIV-infected macrophages may facilitate survival of these cells (32), whereas HIV proteins induce oxidative stress by disrupting mitochondrial biogenesis (33, 34) (Fig. 2).…”

“…Interestingly, although it is acknowledged that the Akt-mTORC1 pathway regulates glycolytic metabolism in T cells and contributes to their inflammatory responses (51), the Akt-mTORC1 axis was recently shown to regulate a subset of M2 genes via Acyl-CoA production and histone acetylation (52). It appears that HIV potently induces hexokinase expression in infected macrophages via viral protein R. Hexokinase may play a nonmetabolic role by binding to mitochondria, thereby maintaining mitochondrial integrity and viability of HIV-infected macrophages (32). Disrupting this association between hexokinase and mitochondria to induce apoptosis in persistently infected macrophages may prove valuable in reducing the macrophage HIV reservoir.…”