UCP1-independent signaling involving SERCA2b-mediated calcium cycling regulates beige fat thermogenesis and systemic glucose homeostasis

K Ikeda, Q Kang, T Yoneshiro, JP Camporez, H Maki… - Nature medicine, 2017 - nature.com
K Ikeda, Q Kang, T Yoneshiro, JP Camporez, H Maki, M Homma, K Shinoda, Y Chen, X Lu…
Nature medicine, 2017nature.com
Abstract Uncoupling protein 1 (UCP1) plays a central role in nonshivering thermogenesis in
brown fat; however, its role in beige fat remains unclear. Here we report a robust UCP1-
independent thermogenic mechanism in beige fat that involves enhanced ATP-dependent
Ca2+ cycling by sarco/endoplasmic reticulum Ca2+-ATPase 2b (SERCA2b) and ryanodine
receptor 2 (RyR2). Inhibition of SERCA2b impairs UCP1-independent beige fat
thermogenesis in humans and mice as well as in pigs, a species that lacks a functional …
Abstract
Uncoupling protein 1 (UCP1) plays a central role in nonshivering thermogenesis in brown fat; however, its role in beige fat remains unclear. Here we report a robust UCP1-independent thermogenic mechanism in beige fat that involves enhanced ATP-dependent Ca2+ cycling by sarco/endoplasmic reticulum Ca2+-ATPase 2b (SERCA2b) and ryanodine receptor 2 (RyR2). Inhibition of SERCA2b impairs UCP1-independent beige fat thermogenesis in humans and mice as well as in pigs, a species that lacks a functional UCP1 protein. Conversely, enhanced Ca2+ cycling by activation of α1- and/or β3-adrenergic receptors or the SERCA2b–RyR2 pathway stimulates UCP1-independent thermogenesis in beige adipocytes. In the absence of UCP1, beige fat dynamically expends glucose through enhanced glycolysis, tricarboxylic acid metabolism and pyruvate dehydrogenase activity for ATP-dependent thermogenesis through the SERCA2b pathway; beige fat thereby functions as a 'glucose sink' and improves glucose tolerance independently of body weight loss. Our study uncovers a noncanonical thermogenic mechanism through which beige fat controls whole-body energy homeostasis via Ca2+ cycling.
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