Blockade of Human Immunodeficiency Virus Type 1 Expression by Caveolin-1

Caveolin 1 (Cav-1) is a major protein of a specific membrane lipid raft known as caveolae. Cav-1 interacts with the gp41 of the human immunodeficiency virus (HIV) envelope, but the role of Cav-1 in HIV replication and pathogenesis is not known. In this report, we demonstrate that HIV infection in primary human monocytederived macrophages (MDMs), THP-1 macrophages, and U87-CD4 cells results in a dramatic upregulation of Cav-1 expression mediated by HIV Tat. The activity of p53 is essential for Tat-induced Cav-1 expression, as our findings show enhanced phosphorylation of serine residues at amino acid positions 15 and 46 in the presence of Tat with a resulting Cav-1 upregulation. Furthermore, inhibition of p38 mitogen-activated protein kinase (MAPK) blocked phosphorylation of p53 in the presence of Tat. Infection studies of Cav-1-overexpressing cells reveal a significant reduction of HIV production. Taken together, these results suggest that HIV infection enhances the expression of Cav-1, which subsequently causes virus reduction, suggesting that Cav-1 may contribute to persistent infection in macrophages.

mentioning

confidence: 86%

HIV Infection Upregulates Caveolin 1 Expression To Restrict Virus Production

Lin

Wang

Nadeau

et al. 2010

“…We have also shown that HIV infection in primary human monocyte-derived macrophages (MDMs) results in a dramatic upregulation of Cav-1 expression mediated by HIV Tat (31). The overexpression of Cav-1 significantly inhibits HIV replication (31,34), implicating Cav-1 as playing a role in HIV's persistent infection of macrophages. However, the mechanism by which Cav-1 inhibits HIV replication remains to be determined.…”

mentioning

confidence: 87%

“…We and others have previously reported that Cav-1 inhibits HIV replication (31,34). In order to determine the mechanisms of Cav-1-mediated reduction of HIV replication, we evaluated the expression of luciferase under the control of the HIV LTR using a provirus that is defective for Env and has the coding sequence of luciferase placed in the Nef region (pNL4-3.Luc.R Ϫ E Ϫ ).…”

Section: Cav-1 Inhibits Gene Expression Under the Control Of The Hiv mentioning

confidence: 99%

Caveolin 1 Inhibits HIV Replication by Transcriptional Repression Mediated through NF-κB

Wang

Nadeau

Lin

et al. 2011

Caveolin 1 (Cav-1), the scaffold protein of a specific membrane lipid raft called caveolae, has been reported to suppress HIV-1 replication. However, the mechanism by which Cav-1 inhibits HIV replication remains unclear. In this study, we investigated the mechanism by which Cav-1 inhibits HIV replication at the level of gene expression. Our results show that Cav-1 represses viral gene expression and that this suppression involves the NF-B pathway. We used several approaches in different cell types, including primary CD4 Caveolae are flask-shaped small invaginations, 50 to 100 nm in diameter, on the plasma membrane that are highly enriched in cholesterol, phospholipids, and sphingolipids and are abundant in various cell types (43,46,54,55,61). These organelles provide scaffolding for compartmented cellular processes and participate in multiple cellular functions, including endocytosis, transcytosis, cholesterol transport, suppression of cell transformation, and signal transduction (15,16,29,32,33,42,46,47,53,60). The caveolae structure is composed of proteins known as caveolins (Cav), and three types (Cav-1, Cav-2, and Cav-3) have been identified (27,42). Cav-1 is the major coat protein responsible for caveolae assembly (14, 28) and is highly expressed in quiescent or terminally differentiated cells, including dendritic cells and monocyte/macrophages (17,19,36,43,46,51,54,55,61). The Cav-1 protein is generally believed to be absent from lymphocytes. This protein can positively or negatively regulate signaling by interacting directly or indirectly with caveolae-resident proteins (6,7,18,36,46,50,60).The caveolin scaffolding domain (CSD), residues 82 to 101 in Cav-1, is essential for both caveolin oligomerization and the interaction of caveolins with other proteins (11). Interactions with other proteins through the CSD help provide coordinated and efficient signal transduction (51, 60). The CSD serves as a receptor for binding proteins containing sequence motif X XXXX, XXXXXX, or XXXXXXX ( representing any aromatic amino acid and X any other amino acid) (11). By using the CSD domain as a receptor, a conserved Cav-1 binding motif, WNNMTWMQW, is identified in the ectodomain (the C-terminal heptad repeat region) of human immunodeficiency virus type 1 (HIV-1) transmembrane envelope glycoprotein gp41 (21,23). This motif in the HIV Env has been shown to interact specifically with the CSD domain of Cav-1. Our group revealed the interaction of cellular Cav-1 and HIV Env (via gp41) within the lipid rafts and further demonstrated that Cav-1 modulates Env-induced bystander apoptosis through the interaction with gp41, as well as fusion mediated by HIV Env (58). We have also shown that HIV infection in primary human monocyte-derived macrophages (MDMs) results in a dramatic upregulation of Cav-1 expression mediated by HIV Tat (31). The overexpression of Cav-1 significantly inhibits HIV replication (31, 34), implicating Cav-1 as playing a role in HIV's persistent infection of macrophages. However, the mechanism by which Cav-1 inh...

“…Primers for HIV-1 were 5Ј-ATATTCTAGAATGTTTTTAGATGGAATAGATAAGGCCC-3Ј and 5Ј-ATATGGGCCCATCCTCATCCTGTCTACCTGCC-3Ј. The amplicons were inserted as Xba/ApaI fragments into pCMV-Myc, which contains the promoter and intron A of the human cytomegalovirus (CMV) immediate early gene (45). MoMLV integrase was amplified with 5Ј-ATATGAATTCATGATAGAA AATTCATCACC-3Ј and 5Ј-TATAGAATTCTTACAGATCCTCTTCTGAGA TGAGTTTTTGTTCGGGGGCCTCGCGG-3Ј and inserted as EcoRI fragments into pCMV and pCMV2, which lacks intron A.…”

Section: Methodsmentioning

confidence: 99%

LEDGF/p75 Determines Cellular Trafficking of Diverse Lentiviral but Not Murine Oncoretroviral Integrase Proteins and Is a Component of Functional Lentiviral Preintegration Complexes

Llano

Vanegas

Fregoso

et al. 2004

Self Cite

272

419

Human immunodeficiency virus type 1 (HIV-1), feline immunodeficiency virus (FIV), and Moloney murine leukemia virus (MoMLV) integrases were stably expressed to determine their intracellular trafficking. Each lentiviral integrase localized to cell nuclei in close association with chromatin while the murine oncoretroviral integrase was cytoplasmic. Fusions of pyruvate kinase to the lentiviral integrases did not reveal transferable nuclear localization signals. The intracellular trafficking of each was determined instead by the transcriptional coactivator LEDGF/p75, which was required for nuclear localization. Stable small interfering RNA expression eliminated detectable LEDGF/p75 expression and caused dramatic, stable redistribution of each lentiviral integrase from nucleus to cytoplasm while the distribution of MoMLV integrase was unaffected. In addition, endogenous LEDGF/p75 coimmunoprecipitated specifically with each lentiviral integrase. In vitro integration assays with preintegration complexes (PICs) showed that endogenous LEDGF/p75 is a component of functional HIV-1 and FIV PICs. However, HIV-1 and FIV infection and replication in LEDGF/p75-deficient cells was equivalent to that in control cells, whether cells were dividing or growth arrested. Two-long terminal repeat circle accumulation in nondividing cell nuclei was also equivalent to that of LEDGF/p75 wild-type cells. Virions produced in LEDGF/p75-deficient cells had normal infectivity. We conclude that LEDGF/p75 fully accounts for cellular trafficking of diverse lentiviral, but not oncoretroviral, integrases and is the main lentiviral integraseto-chromatin tethering factor. While lentiviral PIC nuclear import is unaffected by LEDGF/p75 knockdown, this protein is a component of functional lentiviral PICs. A role in HIV-1 integration site distribution merits investigation.