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Yang B, Yao JL, Huo JY, Feng YL, Coetzee WA, Xu GY, Yang HQ. Rab35 GTPase positively regulates endocytic recycling of cardiac K ATP channels. Channels (Austin) 2022; 16:137-147. [PMID: 35754325 DOI: 10.1080/19336950.2022.2090667] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
Abstract
ATP-sensitive K+ (KATP) channel couples membrane excitability to intracellular energy metabolism. Maintaining KATP channel surface expression is key to normal insulin secretion, blood pressure and cardioprotection. However, the molecular mechanisms regulating KATP channel internalization and endocytic recycling, which directly affect the surface expression of KATP channels, are poorly understood. Here we used the cardiac KATP channel subtype, Kir6.2/SUR2A, and characterized Rab35 GTPase as a key regulator of KATP channel endocytic recycling. Electrophysiological recordings and surface biotinylation assays showed decreased KATP 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 KATP channels. Rab35 also regulated KATP 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 KATP channel trafficking defects.
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Affiliation(s)
- Bo Yang
- Cyrus Tang Medical Institute, Soochow University, Suzhou, Jiangsu, China
| | - Jia-Lu Yao
- Department of Cardiology, the First Affiliated Hospital of Soochow University, Soochow University, Suzhou, Jiangsu, China.,Department of Cardiology, Dushu Lake Hospital Affiliated to Soochow University, Medical Center of Soochow University, Suzhou Dushu Lake Hospital, Suzhou, Jiangsu, China
| | - Jian-Yi Huo
- Cyrus Tang Medical Institute, Soochow University, Suzhou, Jiangsu, China
| | - Yu-Long Feng
- Cyrus Tang Medical Institute, Soochow University, Suzhou, Jiangsu, China
| | - William A Coetzee
- Departments of Pathology, Neuroscience & Physiology, Biochemistry and Molecular Pharmacology, New York University School of Medicine, New York, NY, USA
| | - Guang-Yin Xu
- Jiangsu Key Laboratory of Neuropsychiatric Diseases, Institute of Neuroscience, Soochow University, Suzhou, Jiangsu, China.,Center for Translational Medicine, The Affiliated Zhangjiagang Hospital of Soochow University, Suzhou, Jiangsu, China
| | - Hua-Qian Yang
- Cyrus Tang Medical Institute, Soochow University, Suzhou, Jiangsu, China
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Kawai K, Nishigaki A, Moriya S, Egami Y, Araki N. Rab10-Positive Tubular Structures Represent a Novel Endocytic Pathway That Diverges From Canonical Macropinocytosis in RAW264 Macrophages. Front Immunol 2021; 12:649600. [PMID: 34135890 PMCID: PMC8203412 DOI: 10.3389/fimmu.2021.649600] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2021] [Accepted: 05/11/2021] [Indexed: 12/19/2022] Open
Abstract
Using the optogenetic photo-manipulation of photoactivatable (PA)-Rac1, remarkable cell surface ruffling and the formation of a macropinocytic cup (premacropinosome) could be induced in the region of RAW264 macrophages irradiated with blue light due to the activation of PA-Rac1. However, the completion of macropinosome formation did not occur until Rac1 was deactivated by the removal of the light stimulus. Following PA-Rac1 deactivation, some premacropinosomes closed into intracellular macropinosomes, whereas many others transformed into long Rab10-positive tubules without forming typical macropinosomes. These Rab10-positive tubules moved centripetally towards the perinuclear Golgi region along microtubules. Surprisingly, these Rab10-positive tubules did not contain any endosome/lysosome compartment markers, such as Rab5, Rab7, or LAMP1, suggesting that the Rab10-positive tubules were not part of the degradation pathway for lysosomes. These Rab10-positive tubules were distinct from recycling endosomal compartments, which are labeled with Rab4, Rab11, or SNX1. These findings suggested that these Rab10-positive tubules may be a part of non-degradative endocytic pathway that has never been known. The formation of Rab10-positive tubules from premacropinosomes was also observed in control and phorbol myristate acetate (PMA)-stimulated macrophages, although their frequencies were low. Interestingly, the formation of Rab10-positive premacropinosomes and tubules was not inhibited by phosphoinositide 3-kinase (PI3K) inhibitors, while the classical macropinosome formation requires PI3K activity. Thus, this study provides evidence to support the existence of Rab10-positive tubules as a novel endocytic pathway that diverges from canonical macropinocytosis.
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Affiliation(s)
- Katsuhisa Kawai
- Department of Histology and Cell Biology, School of Medicine, Kagawa University, Miki, Japan
| | - Arata Nishigaki
- Department of Histology and Cell Biology, School of Medicine, Kagawa University, Miki, Japan
| | - Seiji Moriya
- Department of Histology and Cell Biology, School of Medicine, Kagawa University, Miki, Japan
| | - Youhei Egami
- Department of Histology and Cell Biology, School of Medicine, Kagawa University, Miki, Japan
| | - Nobukazu Araki
- Department of Histology and Cell Biology, School of Medicine, Kagawa University, Miki, Japan
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