The Physiological Significance of TRP and Piezo Channels as Physical Stimulus Sensors in Brown Adipocytes.

Most transient receptor potential (TRP) channels are Ca2+-permeable non-selective cation channels that function as polymodal receptors activated by a wide variety of stimuli, including natural compounds such as pungent substances, physical stimuli, lipids, intracellular signaling molecules, and ions. Their physiological roles are diverse, including sensory perception, ion transport, and intracellular signaling. Similarly, Piezo channels, which are also Ca2+-permeable non-selective cation channels, are activated by mechanical stimuli such as membrane stretching and contribute to touch sensation, blood flow regulation, and bladder-filling sensation, among other functions. While research on non-selective cation channels in relation to energy metabolism has primarily focused on TRP channels expressed in primary afferent neurons, studies over the past decade have revealed the important roles of TRP and Piezo channels in brown adipocytes. In this review, we highlight evidence regarding the contributions of TRPV2 and Piezo1 to brown adipocyte differentiation and thermogenesis and briefly summarize recent advances regarding other TRP channels expressed in brown adipocytes. Furthermore, we propose a conceptual framework in which a "modal shift" in TRP/Piezo channels, defined as developmental stage-dependent changes in their functional properties, may contribute to the regulation of brown adipocytes' functions.