Nef, an important pathogenicity factor of human immunodeficiency virus (HIV) and simian immunodeficiency virus (SIV), elevates virus replication in vivo. Among other activities, Nef affects T-cell receptor (TCR) signaling via several mechanisms. For HIV-1 Nef these include alteration of the organization and function of the immunological synapse (IS) such as relocalization of the Lck kinase, as well as early inhibition of TCR/CD3 complex (TCR-CD3)-mediated actin rearrangements and tyrosine phosphorylation. Although most SIV and HIV-2 Nef alleles (group 2) potently downregulate cell surface TCR-CD3, this activity was lost in the viral lineage that gave rise to HIV-1 and its SIV counterparts (group 1). To address the contribution of TCR-CD3 downregulation to Nef effects on TCR signal initiation, we compared the activities of 18 group 1 and group 2 Nef proteins, as well as SIV Nef mutants with defects in TCR-CD3 downmodulation. We found that alteration of Lck's subcellular localization is largely conserved and occurs independently of actin remodeling inhibition or TCR-CD3 downregulation. Surprisingly, Nef proteins of both groups also strongly reduced TCR-induced actin remodeling and tyrosine phosphorylation on TCR-stimulatory surfaces and TCR-CD3 downmodulation competence by group 2 Nef proteins only slightly elevated these effects. Furthermore, Nef proteins from HIV-1 and SIV reduced conjugation between infected primary human T lymphocytes and Raji B cells and potently prevented F-actin polarization at the IS independently of their ability to downmodulate TCR-CD3. These results establish alterations of early TCR signaling events at the IS, including F-actin remodeling and relocalization of Lck, as evolutionary conserved activities of highly divergent lentiviral Nef proteins.
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http://dx.doi.org/10.1128/JVI.01423-09 | DOI Listing |
ESC Heart Fail
December 2024
Department of Internal Medicine, Justus-Liebig-University Giessen, Universities of Giessen and Marburg Lung Center (UGMLC), Institute for Lung Health (ILH), Cardio-Pulmonary Institute (CPI), Member of the German Center for Lung Research (DZL), Giessen, Germany.
Aims: SPARCL1 was recently identified as a biomarker of right ventricular (RV) maladaptation in patients with pulmonary hypertension (PH), and N-terminal pro-brain natriuretic protein (NT-proBNP) is an established biomarker of RV failure in PH. The present study investigated whether NT-proBNP and SPARCL1 concentrations are associated with load-independent parameters of RV function and RV-to-pulmonary artery (RV-PA) coupling as measured using invasive pressure-volume (PV) loops in the RV.
Methods: SPARCL1 and NT-proBNP were measured in the plasma of patients with idiopathic pulmonary artery hypertension (IPAH, n = 73).
Background: Current HIV prophylactic vaccines evaluate HIV Env as purified proteins. CD40.HIVRI.
View Article and Find Full Text PDFViruses
October 2024
St. Petersburg Pasteur Institute, St. Petersburg 197101, Russia.
Human immunodeficiency virus (HIV) continues to be a global health challenge, with over 38 million people infected by the end of 2022. HIV-1, the predominant strain, primarily targets and depletes CD4+ T cells, leading to immunodeficiency and subsequent vulnerability to opportunistic infections. Despite the progress made in antiretroviral therapy (ART), drug resistance and treatment-related toxicity necessitate novel therapeutic strategies.
View Article and Find Full Text PDFMedicina (Kaunas)
November 2024
Department of Psychiatry, Faculty of Medical Sciences, University of Kragujevac, 34000 Kragujevac, Serbia.
ACS Med Chem Lett
November 2024
Department of Chemistry, School of Arts and Sciences, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States.
The ability of the HIV-1 accessory proteins Nef and Vpu to decrease CD4 protects infected cells from antibody-dependent cellular cytotoxicity (ADCC) by limiting the exposure of vulnerable epitopes to envelope glycoprotein (Env). Small-molecule CD4 mimetics (CD4mcs) based on piperidine scaffolds represent a new family of agents capable of sensitizing HIV-1-infected cells to ADCC by exposing CD4-induced (CD4i) epitopes on Env that are recognized by non-neutralizing antibodies which are abundant in plasma of people living with HIV. Here, we employed the combined methods of parallel synthesis, structure-based design, and optimization to generate a new line of piperidine-based CD4mcs, which sensitize HIV-1 infected cells to ADCC activity.
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