Ca2+ Depletion in the ER Causes Store-Operated Ca2+ Entry via the TRPC6 Channel in Mouse Brown Adipocytes.
Physiol Res 2024;
73:69-80. [PMID:
38466006 PMCID:
PMC11019620 DOI:
10.33549/physiolres.935071]
[Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2023] [Accepted: 10/31/2023] [Indexed: 04/26/2024] Open
Abstract
beta3-adrenergic activation causes Ca2+ release from the mitochondria and subsequent Ca2+ release from the endoplasmic reticulum (ER), evoking store-operated Ca2+ entry (SOCE) due to Ca2+ depletion from the ER in mouse brown adipocytes. In this study, we investigated how Ca2+ depletion from the ER elicits SOCE in mouse brown adipocytes using fluorometry of intracellular Ca2+ concentration ([Ca2+]i). The administration of cyclopiazonic acid (CPA), a reversible sarcoplasmic/endoplasmic reticulum calcium ATPase (SERCA) pump blocker in the ER, caused an increase in [Ca2+]i. Moreover, CPA induced SOCE was suppressed by the administration of a Ca2+ free Krebs solution and the transient receptor potential canonical 6 (TRPC6) selective blockers 2-APB, ML-9 and GsMTx-4 but not Pico145, which blocks TRPC1/4/5. Administration of TRPC6 channel agonist 1-oleoyl-2-acetyl-sn-glycerol (OAG) and flufenamic acid elicited Ca2+ entry. Moreover, our RT-PCR analyses detected mRNAs for TRPC6 in brown adipose tissues. In addition, western blot analyses showed the expression of the TRPC6 protein. Thus, TRPC6 is one of the Ca2+ pathways involved in SOCE. These modes of Ca2+ entry provide the basis for heat production via activation of Ca2+-dependent dehydrogenase and the expression of uncoupling protein 1 (UCP1). Enhancing thermogenic metabolism in brown adipocytes may serve as broad therapeutic utility to reduce obesity and metabolic syndrome.
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