Article

Caveolin-1 scaffold domain interacts with TRPC1 and IP3R3 to regulate Ca2+ store release-induced Ca2+ entry in endothelial cells. Am J Physiol Cell Physiol 296:C403-C413

Dept. of Pharmacology (M/C 868) College of Medicine, Univ. of Illinois
AJP Cell Physiology (Impact Factor: 3.78). 03/2009; 296(3):C403-13. DOI: 10.1152/ajpcell.00470.2008
Source: PubMed

ABSTRACT

Caveolin-1 (Cav-1) regulates agonist-induced Ca2+ entry in endothelial cells; however, how Cav-1 regulates this process is poorly understood. Here, we describe that Cav-1 scaffold domain (NH2- terminal residues 82-101; CSD) interacts with transient receptor potential canonical channel 1 (TRPC1) and inositol 1,4,5-trisphosphate receptor 3 (IP 3R3) to regulate Ca2+ entry. We have shown previously that the TRPC1 COOH-terminal residues 781-789 bind to CSD. In the present study, we show that the TRPC1 COOH-terminal residues 781-789 truncated (TRPC1-CΔ781-789) mutant expression abolished Ca2+ store release-induced Ca2+ influx in human dermal microvascular endothelial cell line (HMEC) and human embryonic kidney (HEK-293) cells. To understand the basis of loss of Ca2+ influx, we determined TRPC1 binding to IP3R3. We observed that the wild-type (WT)-TRPC1 but not TRPC1-CΔ781-789 effectively interacted with IP3R3. Similarly, WT-TRPC1 interacted with Cav-1, whereas TRPC1-CΔ781-789 binding to Cav-1 was markedly suppressed. We also assessed the direct binding of Cav-1 with TRPC1 and observed that the WT-Cav-1 but not the Cav-1ΔCSD effectively interacted with TRPC1. Since the interaction between TRPC1 and Cav-1ΔCSD was reduced, we measured Ca2+ store release-induced Ca2+ influx in Cav-1ΔCSD-transfected cells. Surprisingly, Cav-1ΔCSD expression showed a gain-of-function in Ca2+ entry in HMEC and HEK-293 cells. We observed a similar gain-of-function in Ca2+ entry when Cav-1ΔCSD was expressed in lung endothelial cells of Cav-1 knockout mice. Immunoprecipitation results revealed that WT-Cav-1 but not Cav-1ΔCSD interacted with IP3R3. Furthermore, we observed using confocal imaging the colocalization of IP3R3 with WT-Cav-1 but not with Cav-1ΔCSD on Ca2+ store release in endothelial cells. These findings suggest that CSD interacts with TRPC1 and IP3R3 and thereby regulates Ca2+ store release-induced Ca2+ entry in endothelial cells.

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    • "In regard to endothelial cells as mentioned above, studies have shown that the caveolar microdomain organizes and compartmentalizes the SOCE channel complex [75] [77]. Additionally, it has been shown that Cav-1 scaffolding domain interacts with both TRPC1 and IP 3 R 3 and thereby it regulates Ca 2+ store release-induced Ca 2+ entry in endothelial cells [124]. This implies a relevant role of Cav-1 in SOCE functioning and Ca 2+ signaling. "
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    • "Consistent with this, several Ca 2+ signaling components, including TRPC channels, localize within caveolar domains (Pani and Singh, 2009). TRPC1 associates with Cav1 which serves as scaffold to retain the channel in the plasma membrane region and facilitate its interaction with STIM1 (Pani et al., 2009; Sundivakkam et al., 2009). Recent studies also suggest a role of lipid rafts domains (LRD) and Cav1 in regulation of Orai1 (Sathish et al., 2012; Yu et al., 2010). "
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    • "Several TRPC proteins have been reported to partition into detergent-resistant membranes [44-50], and TPRC1 binds to caveolin-1, a lipid raft-associated protein [45,47-49,51-53]. Furthermore, STIM1 overexpression was reported to shift TRPC1 into lipid rafts, thereby altering its channel properties [52,54,55]. "
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