A structural basis for the acute effects of HIV protease inhibitors on GLUT4 intrinsic activity

Department of Cell Biology and Physiology, Washington University in St. Louis, San Luis, Missouri, United States
Journal of Biological Chemistry (Impact Factor: 4.6). 01/2005; 279(53):55147-52. DOI: 10.1074/jbc.M410826200
Source: PubMed

ABSTRACT Human immunodeficiency virus (HIV) protease inhibitors (PIs) act as reversible noncompetitive inhibitors of GLUT4 with binding affinities in the low micromolar range and are known to contribute to alterations in glucose homeostasis during treatment of HIV infection. As aspartyl protease inhibitors, these compounds all possess a core peptidomimetic structure together with flanking hydrophobic moieties. To determine the molecular basis for GLUT4 inhibition, a family of related oligopeptides containing structural elements found in PIs was screened for their ability to inhibit 2-deoxyglucose transport in primary rat adipocytes. The peptide oxybenzylcarbonyl-His-Phe-Phe-O-ethyl ester (zHFFe) was identified as a potent inhibitor of zero-trans glucose flux with a K(i) of 26 mum. Similar to PIs, transport inhibition by this peptide was acute, noncompetitive, and reversible. Within a Xenopus oocyte expression system, zHFFe acutely and reversibly inhibited GLUT4-mediated glucose uptake, whereas GLUT1 activity was unaffected at concentrations as high as 1 mm. The related photoactivatable peptide zHFF-p-benzoylphenylalanine-[(125)I]Tyr-O-ethyl ester selectively labeled GLUT4 in rat adipocytes and indinavir effectively protected against photolabeling. Furthermore, GLUT4 bound to a peptide affinity column containing the zHFF sequence and was eluted by indinavir. These data establish a structural basis for PI effects on GLUT4 activity and support the direct binding of PIs to the transport protein as the mechanism for acute inhibition of insulin-stimulated glucose uptake.

  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: 350 words maximum: (PLEASE TYPE) Combination antiretroviral therapy has dramatically reduced the incidence of HIV-related opportunistic diseases and increased life expectancy. However, antiretroviral therapy is associated with a range of toxicities that can complicate disease management and compromise treatment benefits. Once commenced, antiretroviral therapy is lifelong. Sustained high adherence is essential to maintain clinical benefits, hence prevention of drug-related adverse effects and clinical management of established toxicities are important in ensuring long-term adherence and clinical benefit. Altered lipid metabolism is a common complication of HIV infection and its treatment and a well-established marker of cardiovascular risk. Among antiretroviral agents both inter-and intra-drug class differences in lipid profiles have been described and are essential considerations in drug selection to order to minimize toxicity and reduce future risk. Similarities between the metabolic toxicities of antiretroviral therapy and metabolic syndrome (visceral obesity, dyslipidaemia, hyperglycaemia and hypertension) are of concern given its association with cardiometabolic risk. Few studies have investigated progression to metabolic syndrome in adults commencing antiretroviral therapy. Better understandings of links between metabolic syndrome and subsequent morbidities might allow for more effective clinical management.
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Purpose: We have previously demonstrated that ritonavir targeting of glycolysis is growth inhibitory and cytotoxic in a subset of MM cells. In this study our objective was to investigate the metabolic basis of resistance to ritonavir and to determine the utility of co-treatment with the mitochondrial complex I inhibitor metformin to target compensatory metabolism. Experimental Design: We determined combination indices for ritonavir and metformin, impact on myeloma cell lines, patient samples and myeloma xenograft growth. Additional evaluation in breast, melanoma, and ovarian cancer cell lines was also performed. Signaling connected to suppression of the pro-survival BCL2 family member MCL-1 was evaluated in MM cell lines and tumor lysates. Reliance on oxidative metabolism was determined by evaluation of oxygen consumption and dependence on glutamine was assessed by estimation of viability upon metabolite withdrawal in the context of specific metabolic perturbations. Results: Ritonavir-treated MM cells exhibited increased reliance on glutamine metabolism. Ritonavir sensitized MM cells to metformin, effectively eliciting cytotoxicity both in vitro and in an in vivo xenograft model of MM and in breast, ovarian and melanoma cancer cell lines. Ritonavir and metformin effectively suppressed AKT and mTORC1 phosphorylation and pro-survival BCL-2 family member MCL-1 expression in MM cell lines in vitro and in vivo. Conclusions: FDA-approved ritonavir and metformin effectively target MM cell metabolism to elicit cytotoxicity in MM. Our studies warrant further investigation into repurposing ritonavir and metformin to target the metabolic plasticity of myeloma to more broadly target myeloma heterogeneity and prevent the re-emergence of chemo-resistant aggressive MM. Copyright © 2014, American Association for Cancer Research.
    Clinical Cancer Research 12/2014; DOI:10.1158/1078-0432.CCR-14-1088 · 8.19 Impact Factor
  • Source
    [Show description] [Hide description]
    DESCRIPTION: This literature survey reviews the experimental evidence, known mechanisms and potential treatments of HIV protease inhibitor-induced insulin resistance. HIV protease inhibitors (HPIs) work by preventing the formation of mature, infectious HIV virions. However, HPIs have recently been found to induce insulin resistance, causing hyperglycaemia in HIV-infected patients, seriously denting the validity and the antiretroviral efficacy of HPIs. HPIs cause insulin resistance in a variety of ways: by directly binding to and inhibiting GLUT4 glucose transporters by reversible non-competitive inhibition, by impairing insulin secretory response from pancreatic beta-cells, by decreasing phosphorylation of key proteins within insulin cell signalling pathways such as MAP kinase and protein kinase B, by inhibiting protein kinase B and protein kinase C zeta recruitment to the plasma membrane and by inhibiting critical, non-retroviral cellular proteases such as the 26s proteasome. The lack of HPI substrate-specificity appears to be a major factor in the onset of insulin resistance. Treatments for insulin resistance such as thiazolidinediones and sulphonylureas may be a future therapeutic strategy for HPI-induced insulin resistance, in combination with HPIs, as logically this would reduce the insulin resistant state whilst simultaneously reducing the spread of infectious HIV virions; however, clinical trials in this area are yet to have been carried out.


1 Download
Available from