The Src kinase Lyn is required for CCR5 signaling in response to MIP-1beta and R5 HIV-1 gp120 in human macrophages.
CCR5 is a receptor for several beta chemokines and the entry coreceptor used by macrophage-tropic (R5) strains of HIV-1. In addition to supporting viral entry, CCR5 ligation by the HIV-1 envelope glycoprotein 120 (gp120) can activate intracellular signals in macrophages and trigger inflammatory mediator release. Using a combination of in vitro kinase assay, Western blotting for phospho-specific proteins, pharmacologic inhibition, CCR5 knockout (CCR5Delta32) cells, and kinase-specific blocking peptide, we show for the first time that signaling through CCR5 in primary human macrophages is linked to the Src kinase Lyn. Stimulation of human monocyte-derived macrophages with either HIV-1 gp120 or MIP-1beta results in the CCR5-mediated activation of Lyn and the concomitant Lyn-dependent activation of the mitogen-activated protein (MAP) kinase ERK-1/2. Furthermore, activation of the CCR5/Lyn/ERK-1/2 pathway is responsible for gp120-triggered production of TNF-alpha by macrophages, which is believed to contribute to HIV-1 pathogenesis. Thus, Lyn kinase may play an important role both in normal CCR5 function in macrophages and in AIDS pathogenesis in syndromes such as AIDS dementia where HIV-1 gp120 contributes to inappropriate macrophage activation, mediator production, and secondary injury.
Tomkowicz
Brian
B
Department of Medicine, University of Pennsylvania School of Medicine, Philadelphia, PA 19104, USA.
Lee
Chuhee
C
Ravyn
Vipa
V
Cheung
Ricky
R
Ptasznik
Andrzej
A
Collman
Ronald G
RG
D000163:Acquired Immunodeficiency Syndrome / Q000378:metabolism / Q000473:pathology; D002478:Cells, Cultured; D054407:Chemokine CCL4; D019742:Chemokines, CC / Q000378:metabolism / Q000494:pharmacology*; D015699:HIV Envelope Protein gp120 / Q000378:metabolism / Q000494:pharmacology*; D015497:HIV-1; D006801:Humans; D020935:MAP Kinase Signaling System / Q000187:drug effects*; D019402:Macrophage Inflammatory Proteins / Q000378:metabolism / Q000494:pharmacology*; D008264:Macrophages / Q000201:enzymology* / Q000473:pathology; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3 / Q000378:metabolism; D019713:Receptors, CCR5 / Q000378:metabolism*; D014409:Tumor Necrosis Factor-alpha / Q000096:biosynthesis; D019061:src-Family Kinases / Q000378:metabolism*
C066507:CCL4 protein, human; D054407:Chemokine CCL4; D019742:Chemokines, CC; D015699:HIV Envelope Protein gp120; D019402:Macrophage Inflammatory Proteins; D019713:Receptors, CCR5; D014409:Tumor Necrosis Factor-alpha; C060902:lyn protein-tyrosine kinase; D019061:src-Family Kinases; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3