Division of Cell Signaling, National Institute for Physiological Sciences, National Institutes for Natural Sciences, Okazaki, Aichi, Japan.
Department of Physiology, Aichi Medical University, Nagakute, Aichi, Japan.
J Physiol. 2022 Oct;600(19):4287-4302. doi: 10.1113/JP283350. Epub 2022 Sep 12.
The transient receptor potential melastatin type 2 (TRPM2) channel is a non-selective cation channel that has high Ca permeability. TRPM2 is sensitive to warm temperatures and is expressed in cells and tissues that are maintained at core body temperature. TRPM2 activity is also regulated by endogenous factors including redox signalling, cytosolic Ca and adenosine diphosphate ribose. As a result of its wide expression and function at core body temperature, these endogenous factors could regulate TRPM2 activity at body temperature under physiological and pathophysiological conditions. We previously reported that cellular redox signalling can lower TRPM2 temperature thresholds, although the mechanism that regulates these thresholds is unclear. Here, we used biochemical and electrophysiological techniques to explore another regulatory mechanism for TRPM2 temperature thresholds that is mediated by TRPM2 phosphorylation. Our results show that: (1) the temperature threshold for TRPM2 activation is lowered by cytosolic Ca ; (2) protein kinase C-mediated phosphorylation of TRPM2 counteracts the effect of cytosolic Ca ; and (3) Thr738 in mouse TRPM2 that lies near the Ca binding site in the cytosolic cleft of the transmembrane domain is a potential phosphorylation site that may be involved in phosphorylation-mediated elevation of TRPM2 thresholds. These findings provide structure-based evidence to understand how temperature thresholds of thermo-sensitive TRP channels (thermo-TRPs) are determined and regulated. KEY POINTS: The transient receptor potential melastatin type 2 (TRPM2) ion channel is temperature-sensitive and Ca -permeable. Endogenous factors and pathways such as redox signalling can regulate TRPM2 activity at body temperature under physiological and pathophysiological conditions. In the present study, we report the novel finding that cytosolic Ca lowers the temperature threshold for TRPM2 activation in a concentration-dependent manner. Protein kinase C-mediated phosphorylation of TRPM2 at amino acid Thr782 elevates the temperature threshold for activation by counteracting the effects of cytosolic Ca . These findings provide structure-based evidence to understand how temperature thresholds of thermo-sensitive TRP channels are determined and regulated.
瞬时受体电位 melastatin 型 2（TRPM2）通道是一种非选择性阳离子通道，具有较高的 Ca 通透性。TRPM2 对温暖的温度敏感，并且在维持在核心体温的细胞和组织中表达。TRPM2 活性还受到内源性因素的调节，包括氧化还原信号、细胞溶质 Ca 和二磷酸腺苷核糖。由于其广泛的表达和在核心体温下的功能，这些内源性因素可以在生理和病理生理条件下调节体温下的 TRPM2 活性。我们之前报道过细胞氧化还原信号可以降低 TRPM2 的温度阈值，尽管调节这些阈值的机制尚不清楚。在这里，我们使用生化和电生理技术来探索另一种调节 TRPM2 温度阈值的机制，该机制是由 TRPM2 磷酸化介导的。我们的结果表明：（1）细胞溶质 Ca 降低了 TRPM2 激活的温度阈值；（2）蛋白激酶 C 介导的 TRPM2 磷酸化抵消了细胞溶质 Ca 的作用；（3）位于跨膜域胞质裂隙中 Ca 结合位点附近的小鼠 TRPM2 的 Thr738 是一个潜在的磷酸化位点，可能参与了磷酸化介导的 TRPM2 阈值升高。这些发现提供了基于结构的证据，以了解热敏感 TRP 通道（热 TRP）的温度阈值是如何确定和调节的。关键点：瞬时受体电位 melastatin 型 2（TRPM2）离子通道对温度敏感且 Ca 通透性。氧化还原信号等内源性因素和途径可以在生理和病理生理条件下调节体温下的 TRPM2 活性。在本研究中，我们报告了一个新的发现，即细胞溶质 Ca 以浓度依赖的方式降低了 TRPM2 激活的温度阈值。蛋白激酶 C 介导的 TRPM2 丝氨酸 782 磷酸化通过抵消细胞溶质 Ca 的作用来升高激活的温度阈值。这些发现提供了基于结构的证据，以了解热敏感 TRP 通道的温度阈值是如何确定和调节的。
