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Ectopic ATP synthase facilitates transfer of HIV-1 from antigen-presenting cells to CD4(+) target cells.

ABSTRACT: Antigen-presenting cells (APCs) act as vehicles that transfer HIV to their target CD4(+) cells through an intercellular junction, termed the virologic synapse. The molecules that are involved in this process remain largely unidentified. In this study, we used photoaffinity labeling and a proteomic approach to identify new proteins that facilitate HIV-1 transfer. We identified ectopic mitochondrial ATP synthase as a factor that mediates HIV-1 transfer between APCs and CD4(+) target cells. Monoclonal antibodies against the ?-subunit of ATP synthase inhibited APC-mediated transfer of multiple strains HIV-1 to CD4(+) target cells. Likewise, the specific inhibitors of ATPase, citreoviridin and IF1, completely blocked APC-mediated transfer of HIV-1 at the APC-target cell interaction step. Confocal fluorescent microscopy showed localization of extracellular ATP synthase at junctions between APC and CD4(+) target cells. We conclude that ectopic ATP synthase could be an accessible molecular target for inhibiting HIV-1 proliferation in vivo.

SUBMITTER: Yavlovich A

PROVIDER: S-EPMC3418719 | biostudies-literature | 2012 Aug

REPOSITORIES: biostudies-literature

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Ectopic ATP synthase facilitates transfer of HIV-1 from antigen-presenting cells to CD4(+) target cells.

Yavlovich Amichai A Viard Mathias M Zhou Ming M Veenstra Timothy D TD Wang Ji Ming JM Gong Wanghua W Heldman Eliahu E Blumenthal Robert R Raviv Yossef Y

Blood 20120702 6

Antigen-presenting cells (APCs) act as vehicles that transfer HIV to their target CD4(+) cells through an intercellular junction, termed the virologic synapse. The molecules that are involved in this process remain largely unidentified. In this study, we used photoaffinity labeling and a proteomic approach to identify new proteins that facilitate HIV-1 transfer. We identified ectopic mitochondrial ATP synthase as a factor that mediates HIV-1 transfer between APCs and CD4(+) target cells. Monoclo ...[more]

PMID: 22753871

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Project description:Ectopic adenosine triphosphate synthase (eATP synthase) was found on the cell surface to generate extracellular ATP in various cancer cells. Recently using proteomics approach, several reports identified ATP synthase in extracellular vesicles (EVs) which are important in cell-cell communications. However, the functions of ATP synthase in EVs are still unclear. Here we increased the expression of eATP synthase on the plasma membrane of lung cancer A549 cells via 0.1% FBS starvation and collected EVs including microvesicles and exosomes from the culture medium using serial centrifugation. Both of them were assuredly isolated and confirmed by transmission electron microscopy, nano tracking analysis, and specific EV markers. We also used western blot to demonstrate the presence of ATP synthase in EVs. Besides, dot blot experiment revealed that the F1 portion faced towards extracellular space using anti-ATP beta subunit antibody. Under starvation, the expression of eATP synthase was enhanced on cell surface and exosomes as well as increased EV secretion. To further investigate the functions, we first elucidated whether eATP synthase on EV membrane produced ATP by ATP luciferase analysis. Our data showed that there was no significant ATP production. Moreover, we performed proteomic analysis using dimethyl labeling and LC-MS/MS to compare the difference between EVs released by A549 control and starvation. We identified a total of 1504 and 869 proteins in microvesicles and exosomes, respectively. Using 1.5- and 0.67-fold change as the thresholds, there were 171 and 46 differential expressed proteins in microvesicles and exosomes, respectively. Seven ATP synthase subunits in microvesicles and five in exosomes were identified. The proteomic data were further analyzed using gene set enrichment analysis (GSEA) within the C2 (curated gene sets) subclasses and setting 0.25 as FDR cutoff to find out biological functions related to eATP synthase. Among these up-regulated terms, metabolism, cell cycle and apoptosis were enriched, which indicating that starvation influences cell behavior. Additionally, the immune response is upregulated strikingly in exosomes within C2 gene set. One of these immune response pathways, MHC-1 antigen presentation, was previously proved to interact with eATP synthase which could be recognized by several immune cells.

Project description:Background/objectivesAlthough obesity is associated with low-grade inflammation and metabolic disorders, clinical studies suggested some obese people were metabolically healthy with smaller adipocyte size compared with metabolically abnormal obese (MAO). This indicated adipocyte size may be an important predictor underlay the distinction between MAO and metabolically healthy obese. As recent study has shown that adipocytes expressed class II major histocompatibility complex (MHCII), which functioned as APCs during obesity. However, the relationship between adipocyte hypertrophy and MHCII expression was not involved. Here we hypothesize that hypertrophic adipocytes could be associated with upregulating MHCII to influence adipose tissue metabolism.MethodsAdipocytes were sorted by fluorescence-activated cell sorting (FACS) according to the cell size from MAO mice. The activation of MHCII, T cells and related signaling molecules were examined by FACS, ELISA and western blotting. 3T3-L1 cell line and primary adipocytes were used to examine the effect of free fatty acids (FFA) on adipocytes enlargement and MHCII expression.ResultsMAO mice had a significant increase in adipocytes size and FFA concentration. The large adipocytes from both obese and non-obese mice expressed higher levels of MHCII than small adipocytes. Importantly, large adipocytes from obese mice stimulated CD4(+) T cells to secrete more interferon (IFN)-γ. Furthermore, the activation of the JNK-STAT1 pathway was involved in upregulation of MHCII in large adipocytes. In vitro FFA treatment promoted adipocyte hypertrophy and expression of MHCII-associated genes.ConclusionsThis study demonstrates that large adipocytes highly express MHCII and function as APC to stimulate IFN-γ-expressing CD4(+) T cells, in which FFA may have important roles before IFN-γ elevated. These findings suggest that adipocyte hypertrophy, rather than overall obesity, is the major contributor to adipose tissue inflammation and insulin resistance.

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Ectopic ATP synthase facilitates transfer of HIV-1 from antigen-presenting cells to CD4(+) target cells.

Publications

Ectopic ATP synthase facilitates transfer of HIV-1 from antigen-presenting cells to CD4(+) target cells.

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