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.
Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, NY 10461, USA.
Xianyuan
X
Song
Sakae
S
Tanaka
Dianne
D
Cox
Sunhee C
SC
Lee
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