title: Phosphorylation of SHP-2 regulates interactions between the endoplasmic reticulum and focal adhesions to restrict interleukin-1-induced Ca2+ signaling.
abstract: Interleukin-1 (IL-1)-induced Ca2+ signaling in fibroblasts is constrained by focal adhesions. This process involves the proteintyrosine phosphatase SHP-2, which is critical for IL-1-induced phosphorylation of phospholipase Cgamma1, thereby enhancing IL-1-induced Ca2+ release and ERK activation. Currently, the mechanisms by which SHP-2 modulates Ca2+ release from the endoplasmic reticulum are not defined. We used immunoprecipitation and fluorescence protein-tagged SHP-2 or endoplasmic reticulum (ER)-protein expression vectors, and an ER-specific calcium indicator, to examine the functional relationships between SHP-2, focal adhesions, and IL-1-induced Ca2+ release from the ER. By total internal reflection fluorescence microscopy to image subplasma membrane compartments, SHP-2 co-localized with the ER-associated proteins calnexin and calreticulin at sites of focal adhesion formation in fibroblasts. IL-1beta promoted time-dependent recruitment of SHP-2 and ER proteins to focal adhesions; this process was blocked in cells treated with small interfering RNA for SHP-2 and in cells expressing a Y542F SHP-2 mutant. IL-1 stimulated inositol 1,4,5-trisphosphate receptor-mediated Ca2+ release from the ER subjacent to the plasma membrane that was tightly localized around fibronectin-coated beads and was reduced 4-fold in cells expressing Tyr-542 SHP-2 mutant. In subcellular fractions enriched for ER proteins, immunoprecipitation demonstrated that IL-1-enhanced association of SHP-2 with the type 1 inositol 1,4,5-trisphosphate receptor was dependent on Tyr-542 of SHP-2. We conclude that Tyr-542 of SHP-2 modulates IL-1-induced Ca2+ signals and association of the ER with focal adhesions.
authors.affiliation: Canadian Institutes of Health Research Group in Matrix Dynamics, University of Toronto, Toronto, Ontario M5S 3E2, Canada.
authors.forename: Qin
authors.initials: Q
authors.lastname: Wang
authors.forename: Maria Teresa
authors.initials: MT
authors.lastname: Herrera Abreu
authors.forename: Katherine
authors.initials: K
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; D002118:Calcium / Q000378:metabolism*; D002462:Cell Membrane / Q000378:metabolism; D004721:Endoplasmic Reticulum / Q000378:metabolism*; D005347:Fibroblasts / Q000378:metabolism; D022001:Focal Adhesions / Q000737:chemistry; D006801:Humans; D007375:Interleukin-1 / Q000378:metabolism*; D047908:Intracellular Signaling Peptides and Proteins / Q000737:chemistry* / Q000378:metabolism; D010766:Phosphorylation; D011485:Protein Binding; D054562:Protein Tyrosine Phosphatase, Non-Receptor Type 1; D054592:Protein Tyrosine Phosphatase, Non-Receptor Type 11; D017027:Protein Tyrosine Phosphatases / Q000737:chemistry* / Q000378:metabolism; D051381:Rats; D015398:Signal Transduction; D013347:Subcellular Fractions / Q000378:metabolism
chemical_list: D007375:Interleukin-1; D047908:Intracellular Signaling Peptides and Proteins; C516724:PTPN11 protein, human; D054562:Protein Tyrosine Phosphatase, Non-Receptor Type 1; D054592:Protein Tyrosine Phosphatase, Non-Receptor Type 11; D017027:Protein Tyrosine Phosphatases; C516727:Ptpn11 protein, rat; D002118:Calcium