CACNA1H downregulation induces skeletal muscle atrophy involving endoplasmic reticulum stress activation and autophagy flux blockade
CACNA1H downregulation induces skeletal muscle atrophy involving endoplasmic reticulum stress activation and autophagy flux blockade
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DOI：
10.1038/s41419-020-2484-2
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发表时间：
2020-04-24
影响因子：
9
通讯作者：
Hong, Li
中科院分区：
文献类型：
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作者：
Li, Suting;Hao, Menglei;Hong, Li
多胎阴道分娩（MVD）是导致盆底肌（PFM）功能下降和盆底功能障碍（PFD）的重要因素。PFD多见于中老年女性，但其发病机制尚不清楚。在本研究中，我们发现，与老年或成年小鼠相比，老年小鼠PFM中MVD后CACNA 1H的表达较低。在体外研究中，我们发现用T型Ca 2+通道（T通道）抑制剂NNC-55治疗或通过siRNA干预下调CACNA 1H基因可促进肌管萎缩和凋亡。从机制上讲，我们发现NNC-55增加了肌管中GRP 78和DDIT 3的表达，表明内质网应激（ERS）激活，IRE 1和PERK通路可能参与了这种作用。NNC-55诱导自噬体的形成，但抑制自噬通量。此外，自噬激活剂雷帕霉素不能挽救NNC-55诱导的肌管萎缩或凋亡，自噬抑制剂3-MA和HCQ加速了这种损伤。进一步的研究表明，ERS抑制剂4-PBA和TUDAC缓解了NNC-55诱导的损伤和自噬通量阻断。最后，我们发现Cacna 1h（-/-）（TH-null）小鼠的多部位肌肉萎缩和肌肉功能下降，以及MVD和TH-null小鼠后老年WT小鼠PFM中自噬抑制和凋亡信号增加。总之，我们的研究结果表明，MVD相关的PFD部分归因于CACNA 1H下调诱导的PFM萎缩，ERS是这种疾病的潜在治疗靶点。
Multiple vaginal delivery (MVD) is an important factor for pelvic floor muscle (PFM) function decline and pelvic floor dysfunction (PFD). PFD is common in middle-aged and elderly women, but its pathogenesis is not clear. In this study, we found that the expression of CACNA1H was lower in the PFM of old mice after MVD compared with old or adult mice. In in-vitro studies, we found that treatment with the T-type Ca2+ channel (T-channel) inhibitor NNC-55 or downregulation of the CACNA1H gene by siRNA intervention promoted myotube atrophy and apoptosis. Mechanistically, we revealed that NNC-55 increased the expression of GRP78 and DDIT3 in myotubes, indicating endoplasmic reticulum stress (ERS) activation, and that the IRE1 and PERK pathways might be involved in this effect. NNC-55 induced the formation of autophagosomes but inhibited autophagy flux. Moreover, rapamycin, an autophagy activator, did not rescue myotube atrophy or apoptosis induced by NNC-55, and the autophagy inhibitors 3-MA and HCQ accelerated this damage. Further studies showed that the ERS inhibitors 4-PBA and TUDAC relieved NNC-55-induced damage and autophagy flux blockade. Finally, we found multisite muscle atrophy and decreased muscle function in Cacna1h(-/-) (TH-null) mice, as well as increased autophagy inhibition and apoptotic signals in the PFM of old WT mice after MVD and TH-null mice. Taken together, our results suggest that MVD-associated PFD is partially attributed to CACNA1H downregulation-induced PFM atrophy and that ERS is a potential therapeutic target for this disease.