Members of the thrombospondin gene family bind stromal interaction molecule 1 and regulate calcium channel activity.
The thrombospondins (TSPs) are a family of matricellular proteins that regulate cellular phenotype through interactions with a myriad of other proteins and proteoglycans. We have identified a novel interaction of the members of the TSP gene family with stromal interaction molecule 1 (STIM1). This association is robust since it is preserved in Triton X-100, can be detected with multiple anti-TSP-1 and anti-STIM1 antibodies, and is detected in a wide range of cell types. We have also found that STIM1 co-immunoprecipitates with TSP-4 and cartilage oligomeric matrix protein (COMP), and that a recombinant version of the N-terminal domain of STIM1 binds to the signature domain of TSP-1 and COMP. The association of the TSPs with STIM1 is observed in both the presence and absence of calcium indicating that the calcium-dependent conformation of the signature domain of TSPs is not required for binding. Thus, this interaction could occur in the ER under conditions of normal or low calcium concentration. Furthermore, we observed that the expression of COMP in HEK 293 cells decreases STIM1-mediated calcium release activated calcium (CRAC) channel currents and increases arachidonic acid calcium (ARC) channel currents. These data indicate that the TSPs regulate STIM1 function and participate in the reciprocal regulation of two channels that mediate calcium entry into the cell.
The Division of Experimental Pathology, Department of Pathology, Beth Israel Deaconess Medical School, Harvard Medical School, 99 Brookline Ave., Boston, MA 02215, United States.
Mark
M
Duquette
The Division of Experimental Pathology, Department of Pathology, Beth Israel Deaconess Medical School, Harvard Medical School, 99 Brookline Ave., Boston, MA 02215, United States.
Monica
M
Nadler
Synta Pharmaceuticals, 45 Hartwell Avenue, Lexington, MA 02421, United States.
Dayne
D
Okuhara
The Department of Pharmacology and Physiology, Box 711, University of Rochester Medical Center, 601 Elmwood Avenue, Rochester, NY 14642, United States.
Jill
J
Thompson
The Department of Pharmacology and Physiology, Box 711, University of Rochester Medical Center, 601 Elmwood Avenue, Rochester, NY 14642, United States.
Trevor
T
Shuttleworth
The Division of Experimental Pathology, Department of Pathology, Beth Israel Deaconess Medical School, Harvard Medical School, 99 Brookline Ave., Boston, MA 02215, United States. Electronic address: jlawler@bidmc.harvard.edu.
Jack
J
Lawler
D000818:Animals; D015153:Blotting, Western; D002118:Calcium / Q000378:metabolism; D015220:Calcium Channels / Q000378:metabolism*; D057809:HEK293 Cells; D006801:Humans; D047468:Immunoprecipitation; D013058:Mass Spectrometry; D008565:Membrane Proteins / Q000378:metabolism*; D051379:Mice; D009363:Neoplasm Proteins / Q000378:metabolism*; D018408:Patch-Clamp Techniques; D011994:Recombinant Proteins / Q000378:metabolism*; D000071737:Stromal Interaction Molecule 1; D019700:Thrombospondin 1 / Q000378:metabolism; D019699:Thrombospondins / Q000378:metabolism*
D015220:Calcium Channels; D008565:Membrane Proteins; D009363:Neoplasm Proteins; D011994:Recombinant Proteins; C103530:STIM1 protein, human; D000071737:Stromal Interaction Molecule 1; D019700:Thrombospondin 1; D019699:Thrombospondins; C101864:thrombospondin 4; D002118:Calcium
Arachidonate-regulated calcium channel; Calcium signaling; Stromal interaction molecule 1; Thrombospondin