RESUMO
Chemokines play critical roles in HIV-1 infection, serving both to modulate viral replication and to recruit target cells to sites of infection. Interferon-gamma-inducible protein 10 (IP-10/CXCL10) is a C-X-C chemokine that acts specifically upon activated T cells and macrophages and attracts T cells into the cerebrospinal fluid (CSF) in HIV-associated neurological disease. We now demonstrate that IP-10 stimulates HIV-1 replication in monocyte-derived macrophages and peripheral blood lymphocytes. We further demonstrate that neutralization of endogenous IP-10 or blocking the function of its receptor, CXCR3, reduces HIV-1 replication in these same cells. Therefore, blocking the interaction between IP-10 and CXCR3 represents a possible new target for anti-retroviral therapy.
Assuntos
HIV-1/fisiologia , Receptores de Quimiocinas/fisiologia , Replicação Viral/fisiologia , Adesão Celular , Células Cultivadas , Primers do DNA , DNA Viral/genética , Regulação Viral da Expressão Gênica , Genes Reporter , Repetição Terminal Longa de HIV , HIV-1/genética , HIV-1/patogenicidade , Humanos , Leucócitos Mononucleares/fisiologia , Leucócitos Mononucleares/virologia , Luciferases/genética , Linfócitos/fisiologia , Linfócitos/virologia , Reação em Cadeia da Polimerase/métodos , DNA Polimerase Dirigida por RNA/análise , Receptores CXCR3 , Proteínas Recombinantes/metabolismo , TransfecçãoRESUMO
The viral replication rate in patients infected with human immunodeficiency virus type 1 (HIV-1) is controlled in part by regulation of the transcription of viral genes. The rate of transcription is determined by a complex interplay between cellular and viral proteins and the promoter elements found in the long terminal repeats. Protein phosphatase 2A (PP2A) is a phosphoprotein that plays important roles in the regulation of signal transduction and cell growth. In this report, we demonstrate that overexpression of the catalytic subunit of protein phosphatase 2A (PP2Ac) increases the basal activity of the HIV-1 promoter and, especially, enhances the promoter's response to the protein kinase C (PKC) activator 12-O-tetradecanoyl phorbol-13-acetate (PMA). Additionally, ectopic PP2Ac enhances activation of HIV-1 provirus by PMA. Okadaic acid, a potent inhibitor of PP2A, markedly reduces both HIV-1 enhancer and proviral activation. Fostriecin, a PP2A inhibitor which has been used as an antineoplastic agent in clinical trials, is also able to inhibit PMA-stimulated HIV-1 proviral activation. These observations demonstrate a role for the important cellular phosphatase PP2A in HIV-1 transcription and replication and also suggest that PKC can potentiate the activity of PP2A. PP2A is a potential target for therapeutic intervention in patients infected with HIV-1.
Assuntos
HIV-1/efeitos dos fármacos , Fosfoproteínas Fosfatases/fisiologia , Acetato de Tetradecanoilforbol/farmacologia , Ativação Viral/efeitos dos fármacos , Alcenos/farmacologia , HIV-1/genética , Humanos , Ácido Okadáico/farmacologia , Polienos , Regiões Promotoras Genéticas , Proteína Quinase C/fisiologia , Proteína Fosfatase 2 , Pironas , Fator de Necrose Tumoral alfa/farmacologia , Células U937RESUMO
The development of the complex neoplasm Kaposi's sarcoma is dependent on infection with the Kaposi's sarcoma-associated herpesvirus (KSHV) and appears to be greatly enhanced by cytokines and human immunodeficiency virus type 1 (HIV-1) Tat. Interleukin-8 (IL-8) and growth-regulated oncogene alpha (GRO-alpha) are chemokines involved in chemoattraction, neovascularization, and stimulation of HIV-1 replication. We have previously demonstrated that production of GRO-alpha is stimulated by exposure of monocyte-derived macrophages (MDM) to HIV-1. Here we show that exposure of MDM to HIV-1, viral Tat, or viral gp120 leads to a substantial increase in IL-8 production. We also demonstrate that IL-8 and GRO-alpha are induced by KSHV infection of endothelial cells and are crucial to the angiogenic phenotype developed by KSHV-infected endothelial cells in cell culture and upon implantation into SCID mice. Thus, the three known etiological factors in Kaposi's sarcoma pathogenesis-KSHV, HIV-1 Tat, and cellular growth factors-might be linked, in part, through induction of IL-8 and GRO-alpha.
