Regulation of dynein-mediated autophagosomes trafficking by ASM in CASMCs.
Regulation of dynein-mediated autophagosomes trafficking by ASM in CASMCs.
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DOI：
10.2741/4415
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发表时间：
2016-01-01
期刊：
影响因子：
--
通讯作者：
Zhang Y
中科院分区：
文献类型：
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作者：
Xu M;Zhang Q;Li PL;Nguyen T;Li X;Zhang Y
酸性鞘磷脂酶(ASM；基因符号SMPD1)通过控制溶酶体与自噬小体在冠状动脉平滑肌细胞(CASMCs)中的融合，在自噬成熟过程中发挥关键作用。然而，ASM控制自噬溶酶体融合的潜在分子机制仍不清楚。在原代培养的CASMCs中，7-酮胆固醇(7-Ket，动脉粥样硬化刺激和自噬诱导剂)诱导的溶酶体Ca~(2+)浓度被ASM缺乏或TRPML1基因沉默显著减弱，提示ASM信号是TRPML1通道活动和随后的溶酶体Ca~(2+)释放所必需的。在这些CASMCs中，ASM缺乏或TRPML1基因沉默显著抑制7-Ket诱导的Dynein激活。此外，7-酮诱导的自噬小体转运与溶酶体钙释放和动力蛋白活性有关，与SMPD1CASMC相比，7-Ket诱导的自噬小体转运在SMPD1CASMC中受到显著抑制。最后，TRPML1蛋白的过表达恢复了7-酮诱导的SMPD1CASMCs的溶酶体钙释放和自噬小体转运。综上所述，这些结果表明，ASM在调节溶酶体TRPML1-Ca~(2+)信号和随后动力蛋白介导的自噬小体运输中发挥关键作用，从而在动脉粥样硬化刺激下控制CASMCs的自噬成熟。
Acid sphingomyelinase (ASM; gene symbol Smpd1) has been shown to play a crucial role in autophagy maturation by controlling lysosomal fusion with autophagosomes in coronary arterial smooth muscle cells (CASMCs). However, the underlying molecular mechanism by which ASM controls autophagolysosomal fusion remains unknown. In primary cultured CASMCs, lysosomal Ca2+ induced by 7-ketocholesterol (7-Ket, an atherogenic stimulus and autophagy inducer) was markedly attenuated by ASM deficiency or TRPML1 gene silencing suggesting that ASM signaling is required for TRPML1 channel activity and subsequent lysosomal Ca2+ release. In these CASMCs, ASM deficiency or TRPML1 gene silencing markedly inhibited 7-Ket-induced dynein activation. In addition, 7-Ket-induced autophagosome trafficking, an event associated with lysosomal Ca2+ release and dynein activity, was significantly inhibited in ASM-deficient (Smpd1−/−) CASMCs compared to that in Smpd1+/+ CASMCs. Finally, overexpression of TRPML1 proteins restored 7-Ket-induced lysosomal Ca2+ release and autophagosome trafficking in Smpd1−/− CASMCs. Collectively, these results suggest that ASM plays a critical role in regulating lysosomal TRPML1-Ca2+ signaling and subsequent dynein-mediated autophagosome trafficking, which leads its role in controlling autophagy maturation in CASMCs under atherogenic stimulation.