title: Ras-guanine-nucleotide-releasing factors 1 and 2 interact with PLCγ at focal adhesions to enable IL-1-induced Ca(2+) signalling, ERK activation and MMP-3 expression.
abstract: IL (interleukin)-1 signalling in anchorage-dependent cells involves focal-adhesion-restricted and Ca2+-dependent Ras and ERK (extracellular-signal-regulated kinase) activation that leads to MMP (matrix metalloproteinase) release and extracellular matrix remodelling. Ras activity is regulated, in part, by the Ca2+-responsive Ras GRFs (guanine-nucleotide-releasing factors) 1 and 2, but the mechanisms that link and localize IL-1-induced Ca2+ signalling to focal adhesions are not defined. In the present study we characterized the role of Ras-GRF1/2 in Ca2+ and Ras→ERK signalling after IL-1 stimulation. By immunoprecipitation we found that Ras-GRF1/2 associates with PLCγ1 (phospholipase Cγ1). This association enables PLCγ1 recruitment to focal adhesions and is required for Ras signalling, ERK activation and MMP-3 release downstream of IL-1 stimulation. Depletion of PLCγ1 by siRNA (small interfering RNA) abolished IL-1-induced Ras activation and MMP-3 expression. Buffering of cytosolic Ca2+ reduced Ras interactions with Ras-GRF1/2 and blocked MMP-3 release. The results of the present study show that, in addition to their functions as Ras-exchange factors, Ras-GRF1 and -GRF2 may act as adaptors that bind PLCγ1 and restrict Ca2+ signalling to the vicinity of focal adhesions, indicating a new role for these GRFs that is required for IL-1 induction of the Ras→ERK pathway and MMP-3 expression.
authors.affiliation: Matrix Dynamics Group, Faculty of Dentistry, University of Toronto, Toronto, ON, Canada, M5S 3E2.
authors.forename: Qin
authors.initials: Q
authors.lastname: Wang
authors.forename: Katherine A
authors.initials: KA
authors.lastname: Siminovitch
authors.forename: Gregory P
authors.initials: GP
authors.lastname: Downey
authors.forename: Christopher A
authors.initials: CA
authors.lastname: McCulloch
mesh_terms: D000818:Animals; D020013:Calcium Signaling / Q000187:drug effects; D022001:Focal Adhesions / Q000378:metabolism*; D007375:Interleukin-1 / Q000494:pharmacology; D020935:MAP Kinase Signaling System / Q000187:drug effects; D019278:Matrix Metalloproteinase 3 / Q000378:metabolism*; D051379:Mice; D041681:NIH 3T3 Cells; D051966:Phospholipase C gamma / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D010766:Phosphorylation; D034741:RNA, Small Interfering / Q000235:genetics; D020663:ras Guanine Nucleotide Exchange Factors / Q000378:metabolism*; D020666:ras-GRF1 / Q000378:metabolism*
chemical_list: D007375:Interleukin-1; D034741:RNA, Small Interfering; C513037:Rasgrf1 protein, mouse; C504491:Rasgrf2 protein, mouse; D020663:ras Guanine Nucleotide Exchange Factors; D020666:ras-GRF1; D051966:Phospholipase C gamma; D019278:Matrix Metalloproteinase 3; C511769:Mmp3 protein, mouse