The HIV-envelope protein gp120 plays a critical role in triggering the apoptosis of T-lymphocytes, which is a central pathogenic feature of HIV-mediated immune dysfunction. T-cell apoptosis is also a physiological process that regulates antigen receptor repertoire selection during homeostasis and the maturation of T- cells. We hypothesize that gp120-induced cross-talk between T-cell receptor (TCR) and chemokine receptor signaling pathways leads to apoptosis. Our preliminary data on the role of the TCR signaling components CD45 and SLP-76 in HIV-gpl20-induced apoptosis support this hypothesis. In addition, we have recently shown that cross-talk between TCR and chemokine receptor CXCR4 regulates apoptosis via a novel mechanism that is mediated by AKT/Protein Kinase B (PKB), heat shock protein-70 (HSP-70), caspase-1 and RIP2 (caspase recruitment domain-containing serine/threonine kinase). To analyze mechanistically how the TCR components and chemokine receptors CXCR4/CCR5 regulate gp120-induced apoptosis, we will pursue the following specific aims:
Aim 1) we will assess the interaction between CD45 and CXCR4/CCR5 signaling molecules by defining the domain of CD45 and characterizing the CD45 signaling responsible for apoptosis.
Aim 2) we will perform structural and functional analyses of the TCR-mediated downstream effector SLP-76 that mediates Ca2+dependent apoptotic pathways.
Aim 3) we will analyze the role of the AKT/HSP-70 apoptotic pathway that may lead to the induction of forkhead transcription factors, and will characterize the activation of caspase-1 and its regulation by RIP2. We are also exploring innovative strategies to inhibit gp120-induced apoptosis. In this regard, we have shown that a novel protein, Slit, which binds to the Robo receptor and modulates CXCR4 function can inhibit gp120-induced apoptosis.
Aim 4) we will identify which domains in the Slit/Robo complex regulate the observed anti-apoptotic effects. These studies are designed to identify apoptotic signaling molecules and effector pathways involved in T-cell loss, and thus to provide novel therapeutic targets to combat immune deficiency in AIDS. ? ? ?

Agency
National Institute of Health (NIH)
Institute
National Heart, Lung, and Blood Institute (NHLBI)
Type
Research Project (R01)
Project #
5R01HL087576-04
Application #
7492863
Study Section
AIDS Immunology and Pathogenesis Study Section (AIP)
Program Officer
Mitchell, Phyllis
Project Start
2006-07-01
Project End
2010-06-30
Budget Start
2008-07-01
Budget End
2009-06-30
Support Year
4
Fiscal Year
2008
Total Cost
$375,000
Indirect Cost
Name
Ohio State University
Department
Pathology
Type
Schools of Medicine
DUNS #
832127323
City
Columbus
State
OH
Country
United States
Zip Code
43210
Anand, Appakkudal R; Zhao, Helong; Nagaraja, Tirumuru et al. (2013) N-terminal Slit2 inhibits HIV-1 replication by regulating the actin cytoskeleton. Retrovirology 10:2
Nagaraja, Tirumuru; Chen, Li; Balasubramanian, Anuradha et al. (2012) Activation of the connective tissue growth factor (CTGF)-transforming growth factor ? 1 (TGF-? 1) axis in hepatitis C virus-expressing hepatocytes. PLoS One 7:e46526
Nagaraja, Tirumuru; Anand, Appakkudal R; Zhao, Helong et al. (2012) The adaptor protein SLP-76 regulates HIV-1 release and cell-to-cell transmission in T cells. J Immunol 188:2769-77
Anand, Appakkudal R; Tirumuru Nagaraja; Ganju, Ramesh K (2011) A novel role for Slit2/Robo1 axis in modulating HIV-1 replication in T cells. AIDS 25:2105-11
Anand, Appakkudal R; Bradley, Ritu; Ganju, Ramesh K (2009) LPS-induced MCP-1 expression in human microvascular endothelial cells is mediated by the tyrosine kinase, Pyk2 via the p38 MAPK/NF-kappaB-dependent pathway. Mol Immunol 46:962-8
Anand, Appakkudal R; Prasad, Anil; Bradley, Ritu R et al. (2009) HIV-1 gp120-induced migration of dendritic cells is regulated by a novel kinase cascade involving Pyk2, p38 MAP kinase, and LSP1. Blood 114:3588-600
Balasubramanian, Anuradha; Groopman, Jerome E; Ganju, Ramesh K (2008) Underlying pathophysiology of HCV infection in HIV-positive drug users. J Addict Dis 27:75-82