Rab35 GTPase positively regulates endocytic recycling of cardiac K_ATP channels.

Channels (Austin, Tex.) Pub Date : 2022-12-01 DOI:10.1080/19336950.2022.2090667

Bo Yang, Jia-Lu Yao, Jian-Yi Huo, Yu-Long Feng, William A Coetzee, Guang-Yin Xu, Hua-Qian Yang

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Abstract

ATP-sensitive K⁺ (K_ATP) channel couples membrane excitability to intracellular energy metabolism. Maintaining K_ATP channel surface expression is key to normal insulin secretion, blood pressure and cardioprotection. However, the molecular mechanisms regulating K_ATP channel internalization and endocytic recycling, which directly affect the surface expression of K_ATP channels, are poorly understood. Here we used the cardiac K_ATP channel subtype, Kir6.2/SUR2A, and characterized Rab35 GTPase as a key regulator of K_ATP channel endocytic recycling. Electrophysiological recordings and surface biotinylation assays showed decreased K_ATP channel surface density with co-expression of a dominant negative Rab35 mutant (Rab35-DN), but not other recycling-related Rab GTPases, including Rab4, Rab11a and Rab11b. Immunofluorescence images revealed strong colocalization of Rab35-DN with recycling Kir6.2. Rab35-DN minimized the recycling rate of K_ATP channels. Rab35 also regulated K_ATP channel current amplitude in isolated adult cardiomyocytes by affecting its surface expression but not channel properties, which validated its physiologic relevance and the potential of pharmacologic target for treating the diseases with K_ATP channel trafficking defects.

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Rab35 GTPase正调控心脏KATP通道的内吞循环。

atp敏感的K+ (KATP)通道将细胞膜兴奋性耦合到细胞内能量代谢。维持KATP通道表面表达是胰岛素分泌、血压和心脏保护正常的关键。然而，直接影响KATP通道表面表达的调节KATP通道内化和内吞循环的分子机制尚不清楚。在这里，我们使用心脏KATP通道亚型Kir6.2/SUR2A，并将Rab35 GTPase表征为KATP通道内吞循环的关键调节因子。电生理记录和表面生物素化分析显示，与Rab35显性阴性突变体(Rab35- dn)共表达的KATP通道表面密度降低，但与Rab4、Rab11a和Rab11b等其他回收相关的rabgtpase未表达。免疫荧光图像显示Rab35-DN与循环Kir6.2强共定位。Rab35-DN使KATP通道的再循环率最小化。Rab35还通过影响KATP通道表面表达而不影响通道性质来调节离体成人心肌细胞的KATP通道电流振幅，这证实了其生理相关性和治疗KATP通道运输缺陷疾病的药理学靶点潜力。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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Channels (Austin, Tex.)

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