Gu Zi-Qi, Wang Hsuan-Ti, Li Yanfen, Krogsaeter Einar, Lin Alice C, Lin Jackson, Liu Yi-Shan, Lin Wei-Shuan, Burton William, Liu Mu-Lin, Feldmann Colin, Tang Rachel, Po Ching-Wen, Hou Pei-Shan, Lin Neng-Yu, Lin Jing-Yi, Chao Tai-Ling, Chang Sui-Yuan, Yang Zhuo, Keller Marco, Leser Charlotte, Fenske Stefanie, Bracher Franz, Wahl-Schott Christian, Galione Antony, Tsai Yu-Huan, Grimm Christian, Biel Martin, Chen Cheng-Chang
Laboratory of Host-Microbe Interactions and Cell Dynamics, Department of Medical Biotechnology and Laboratory Science, Chang Gung University, Taoyuan, Taiwan; Institute of Microbiology and Immunology, College of Life Sciences, National Yang Ming Chiao Tung University, Taipei, Taiwan.
Department of Clinical Laboratory Sciences and Medical Biotechnology, College of Medicine, National Taiwan University, Taipei, Taiwan.
Biomed Pharmacother. 2025 Aug;189:118350. doi: 10.1016/j.biopha.2025.118350. Epub 2025 Jul 15.
TRPML2 is an endolysosomal calcium-permeable channel gated by phosphatidylinositol 3,5-bisphosphate (PI(3,5)P₂). However, its subcellular localization and functional contribution to compartment-specific vesicle trafficking remain incompletely defined. In this study, we identify Rab4-positive recycling endosomes as a key site of TRPML2 activity and regulation. We further examined a PI(3,5)P₂-insensitive TRPML2 mutant (R310A), which exhibited reduced channel activity, accumulated perinuclear vesicles, and impaired Rab4 + endosomal motility. To restore channel function, we employed two selective small-molecule TRPML2 agonists, ML2-SA1 and ML2-SA2. Endolysosomal patch-clamp recordings confirmed that both compounds activate wild-type TRPML2 and effectively restore channel activity in the R310A mutant. Functional imaging further demonstrated that ML2-SA2 treatment rescues vesicle redistribution, reduces Golgi accumulation, and promotes peripheral vesicle dynamics. Notably, these effects were observed even in the absence of functional PI(3,5)P₂ gating, indicating that small-molecule agonists can bypass endogenous lipid regulation to restore TRPML2 activity. Our findings identify TRPML2 as a druggable ion channel whose activity is essential for maintaining Rab4-dependent vesicle trafficking. This study establishes a mechanistic link between phosphoinositide sensitivity, TRPML2 activation, and endosomal motility, and highlights a potential therapeutic strategy for correcting trafficking defects caused by impaired lipid signaling in immune cells or other pathophysiological contexts involving endosomal stress.
瞬时受体电位黏蛋白2（TRPML2）是一种内溶酶体钙通透性通道，由磷脂酰肌醇3,5-二磷酸（PI(3,5)P₂）门控。然而，其亚细胞定位以及对特定区室的囊泡运输的功能贡献仍未完全明确。在本研究中，我们确定Rab4阳性再循环内体是TRPML2活性和调控的关键位点。我们进一步研究了一种对PI(3,5)P₂不敏感的TRPML2突变体（R310A），该突变体表现出通道活性降低、核周囊泡积累以及Rab4 +内体运动受损。为恢复通道功能，我们使用了两种选择性小分子TRPML2激动剂，ML2-SA1和ML2-SA2。内溶酶体膜片钳记录证实这两种化合物均可激活野生型TRPML2，并有效恢复R310A突变体中的通道活性。功能成像进一步表明，ML2-SA2处理可挽救囊泡重新分布、减少高尔基体积累并促进外周囊泡动力学。值得注意的是，即使在没有功能性PI(3,5)P₂门控的情况下也观察到了这些效应，这表明小分子激动剂可以绕过内源性脂质调节来恢复TRPML2活性。我们的研究结果确定TRPML2是一种可药物靶向的离子通道，其活性对于维持Rab4依赖性囊泡运输至关重要。本研究建立了磷酸肌醇敏感性、TRPML2激活和内体运动之间的机制联系，并突出了一种潜在的治疗策略，用于纠正免疫细胞或其他涉及内体应激的病理生理背景下脂质信号受损导致的运输缺陷。
