title: Lopinavir inhibits insulin signaling by promoting protein tyrosine phosphatase 1B expression.
abstract: Treatment with antiretroviral therapy, including protease inhibitors (PIs), may result in metabolic side-effects, for example insulin resistance. The aim of the present study was to investigate the mechanism of the dysregulation of insulin signaling by two PIs, lopinavir and darunavir, by analyzing changes in the expression or activity of proteins associated with insulin signaling. 3T3-L1 preadipocytes were pretreated with lopinavir or darunavir for 48 h and then stimulated with insulin for 30 min. The cell lysates were subjected to western blotting with anti-phospho-insulin receptor substrate (IRS) 1, anti-IRS1, anti-suppressor of cytokine signaling (SOCS) 1, anti-SOCS3 and anti-protein tyrosine phosphatase (PTP) 1B antibodies and to immunoprecipitation with anti-IRS1 antibody. Translocation of glucose transporter 4 (GLUT4) following treatment with lopinavir or darunavir was observed using immunofluorescence. While GLUT4 was recruited to the cellular membrane in control adipocytes following insulin stimulation, it was diffusely distributed in the cytosol in lopinavir-treated adipocytes. In darunavir-treated adipocytes, GLUT4 was mainly recruited to the cellular membrane, but some GLUT4 remained in the cytosol. After insulin stimulation, IRS1 was tyrosine-phosphorylated to a greater extent in control adipocytes compared with darunavir-treated adipocytes. Tyrosine phosphorylation of IRS1 was inhibited in lopinavir-treated adipocytes. The expression of PTP1B was upregulated in adipocytes pretreated with the PIs, particularly lopinavir, compared with those pretreated with a vehicle control. The degree of regulation in insulin signaling differs between lopinavir and darunavir. One mechanism by which lopinavir regulates insulin signaling is by the promotion of PTP1B expression.
authors.affiliation: Department of Medicine, Teikyo University School of Medicine, Tokyo 173-8605, Japan.
authors.forename: Takatoshi
authors.initials: T
authors.lastname: Kitazawa
authors.affiliation: Department of Medicine, Teikyo University School of Medicine, Tokyo 173-8605, Japan.
authors.forename: Yusuke
authors.initials: Y
authors.lastname: Yoshino
authors.affiliation: Department of Pulmonary Medicine, Graduate School of Medicine, The University of Tokyo, Tokyo 113-8655, Japan.
authors.forename: Satoshi
authors.initials: S
authors.lastname: Suzuki
authors.affiliation: Department of Medicine, Teikyo University School of Medicine, Tokyo 173-8605, Japan.
authors.forename: Ichiro
authors.initials: I
authors.lastname: Koga
authors.affiliation: Department of Medicine, Teikyo University School of Medicine, Tokyo 173-8605, Japan.
authors.forename: Yasuo
authors.initials: Y
authors.lastname: Ota
keywords: darunavir; insulin; lopinavir; protein tyrosine phosphatase 1B