Caveolin-1 contributes to assembly of store-operated Ca2+ influx channels by regulating plasma membrane localization of TRPC1.
TRPC1, a component of store-operated Ca2+ entry (SOCE) channels, is assembled in a complex with caveolin-1 (Cav1) and key Ca2+ signaling proteins. This study examines the role of Cav1 in the function of TRPC1. TRPC1 and Cav1 were colocalized in the plasma membrane region of human submandibular gland and Madin-Darby canine kidney cells. Full-length Cav1 bound to both the N and C termini of TRPC1. Amino acids 271-349, which includes a Cav1 binding motif (amino acids 322-349), was identified as the Cav1 binding domain in the TRPC1 N terminus. Deletion of amino acids 271-349 or 322-349 prevented plasma membrane localization of TRPC1. Importantly, TRPC1Delta271-349 induced a dominant suppression of SOCE and was associated with wild-type TRPC1. Although the role of the C-terminal Cav1 binding domain is not known, its deletion did not affect localization of TRPC1 (Singh, B. B., Liu, X., and Ambudkar, I. S. (2000) J. Biol. Chem. 275, 36483-36486). Further, expression of a truncated Cav1 (Cav1Delta51-169), but not full-length Cav1, similarly disrupted plasma membrane localization of endogenously and exogenously expressed TRPC1 in human submandibular gland and Madin-Darby canine kidney cells. Cav1Delta51-169 also suppressed thapsigarginand carbachol-stimulated Ca2+ influx and increased the detergent solubility of TRPC1, although plasma membrane lipid raft domains were not disrupted. These data demonstrate that plasma membrane localization of TRPC1 depends on an interaction between its N terminus and Cav1. Thus, our data suggest that Cav1 has an important role in the assembly of SOCE channel(s).
Secretory Physiology Section, Gene Therapy and Therapeutics Branch, Department of Health and Human Services, NIDCR, National Institutes of Health, Bethesda, Maryland 20892, USA.
So-Ching W
SC
Brazer
Brij B
BB
Singh
Xibao
X
Liu
William
W
Swaim
Indu S
IS
Ambudkar
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D001665:Binding Sites; D015220:Calcium Channels / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D020013:Calcium Signaling; D051242:Caveolin 1; D022461:Caveolins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism; D004247:DNA / Q000235:genetics; D004285:Dogs; D006801:Humans; D066298:In Vitro Techniques; D007668:Kidney / Q000378:metabolism; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D013363:Submandibular Gland / Q000378:metabolism; D050052:TRPC Cation Channels; D020798:Two-Hybrid System Techniques
C495540:CAV1 protein, human; D015220:Calcium Channels; D051242:Caveolin 1; D022461:Caveolins; D010446:Peptide Fragments; D011993:Recombinant Fusion Proteins; D050052:TRPC Cation Channels; C096351:transient receptor potential cation channel, subfamily C, member 1; D004247:DNA