Fcgamma receptor signaling in primary human microglia: differential roles of PI-3K and Ras/ERK MAPK pathways in phagocytosis and chemokine induction.
Cryptococcus neoformans monoclonal antibody immune complex (IC) induces beta-chemokines and phagocytosis in primary human microglia via activation of Fc receptor for immunoglobulin G (FcgammaR). In this report, we investigated microglial FcgammaR signal-transduction pathways by using adenoviral-mediated gene transfer and specific inhibitors of cell-signaling pathways. We found that Src inhibitor PP2 and Syk inhibitor piceatannol inhibited phagocytosis, macrophage-inflammatory protein-1alpha (MIP-1alpha) release, as well as phosphorylation of extracellular-regulated kinase (ERK) and Akt, consistent with Src/Syk involvement early in FcgammaR signaling. Constitutively active mitogen-activated protein kinase kinase (MEK) induced MIP-1alpha, and Ras dominant-negative (DN) inhibited IC-induced ERK phosphorylation and MIP-1alpha production. These results suggest that the Ras/MEK/ERK pathway is necessary and sufficient in IC-induced MIP-1alpha expression. Neither Ras DN nor the MEK inhibitor U0126 inhibited phagocytosis. In contrast, phosphatidylinositol-3 kinase (PI-3K) inhibitors Wortmannin and LY294002 inhibited phagocytosis without affecting ERK phosphorylation or MIP-1alpha production. Conversely, Ras DN or U0126 did not affect Akt phosphorylation. Together, these results demonstrate distinct roles played by the PI-3K and Ras/MEK/ERK pathways in phagocytosis and MIP-1alpha induction, respectively. Our results demonstrating activation of functionally distinct pathways following microglial FcgammaR engagement may have implications for human central nervous system diseases.
Song
Xianyuan
X
Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, NY 10461, USA.
Tanaka
Sakae
S
Cox
Dianne
D
Lee
Sunhee C
SC
D000256:Adenoviridae / Q000235:genetics; D001921:Brain / Q000378:metabolism; D002070:Butadienes / Q000494:pharmacology; D054405:Chemokine CCL3; D054407:Chemokine CCL4; D018946:Chemokine CCL5 / Q000096:biosynthesis; D003455:Cryptococcus neoformans / Q000276:immunology; D004792:Enzyme Precursors / Q000378:metabolism; D005260:Female; D005333:Fetus; D005799:Genes, Dominant; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins; D048728:MAP Kinase Kinase Kinase 1; D020930:MAP Kinase Kinase Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D019402:Macrophage Inflammatory Proteins / Q000378:metabolism*; D017628:Microglia / Q000276:immunology* / Q000378:metabolism / Q000382:microbiology; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D009570:Nitriles / Q000494:pharmacology; D010587:Phagocytosis / Q000187:drug effects*; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism*; D010766:Phosphorylation; D011247:Pregnancy; D011505:Protein-Tyrosine Kinases / Q000378:metabolism; D017452:Receptors, IgG / Q000502:physiology*; D015398:Signal Transduction; D013267:Stilbenes / Q000494:pharmacology; D000072377:Syk Kinase; D018631:ras Proteins / Q000378:metabolism*; D019061:src-Family Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism
D002070:Butadienes; D054405:Chemokine CCL3; D054407:Chemokine CCL4; D018946:Chemokine CCL5; D004792:Enzyme Precursors; D047908:Intracellular Signaling Peptides and Proteins; D048728:MAP Kinase Kinase Kinase 1; D020930:MAP Kinase Kinase Kinases; D019402:Macrophage Inflammatory Proteins; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases; D009570:Nitriles; D019869:Phosphatidylinositol 3-Kinases; D011505:Protein-Tyrosine Kinases; D017452:Receptors, IgG; D013267:Stilbenes; D000072377:Syk Kinase; D018631:ras Proteins; D019061:src-Family Kinases; C113580:U 0126; C041525:3,3',4,5'-tetrahydroxystilbene; C000606896:SYK protein, human; C482576:MAP3K1 protein, human