Mitochondrial-specific autophagy linked to mitochondrial dysfunction following traumatic freeze injury in mice
Mitochondrial-specific autophagy linked to mitochondrial dysfunction following traumatic freeze injury in mice
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DOI：
10.1152/ajpcell.00123.2019
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发表时间：
2020-02-01
影响因子：
5.5
通讯作者：
Call, Jarrod A.
中科院分区：
文献类型：
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作者：
Nichenko, Anna S.;Southern, W. Michael;Call, Jarrod A.
本研究的目的是询问骨骼肌中线粒体功能障碍和骨骼肌特异性自噬之间的联系。C57 BL/6 J小鼠用于建立疲劳（n = 12）、离心收缩诱导的损伤（n = 20）或创伤性冷冻损伤（FI，n = 28）后线粒体功能和自噬诱导的时程;仅FI导致线粒体功能障碍的组合，即，减少线粒体呼吸和自噬诱导。展望未来，我们测试了这一假设，即脑特异性自噬对于FI后线粒体功能的及时恢复很重要。FI后，细胞内动力蛋白相关蛋白1（Drp 1）、BCL 1相互作用蛋白3（BNIP 3）、Pink 1和Parkin蛋白含量显著增加（接近2倍，P < 0.02）。此外，从H肌中富集的线粒体组分显示微管相关蛋白轻链B1（LC 3）II共定位，表明自噬体组装在受损的线粒体周围。Unc-51样自噬激活激酶（Ulk 1）被认为是神经特异性自噬所必需的，在此我们利用了成年骨骼肌中Ulk 1缺乏的小鼠模型（肌生成素-Cre）。虽然Ulk 1敲除与同窝对照相比具有收缩无力（-27%，P < 0.02），但线粒体功能的恢复没有不同，这可能部分是由于来自分化的卫星细胞的敲除的再生肌肉组织内Ulk 1蛋白含量的部分拯救，其中Ulk 1没有通过肌细胞生成素-Cre遗传改变。最后，尽管自噬相关蛋白含量增加，但损伤肌肉的自噬通量显著低于未损伤肌肉（-26%，P < 0.02）。这表明自噬通量没有上调以匹配损伤后自噬机制的增加，并且代表了自噬清除受损线粒体的潜在瓶颈。
The objective of this study was to interrogate the link between mitochondrial dysfunction and mitochondrial-specific autophagy in skeletal muscle. C57BL/6J mice were used to establish a time course of mitochondrial function and autophagy induction after fatigue (n = 12), eccentric contraction-induced injury (n = 20), or traumatic freeze injury (FI, n = 28); only FI resulted in a combination of mitochondrial dysfunction, i.e., decreased mitochondrial respiration, and autophagy induction. Moving forward, we tested the hypothesis that mitochondrial-specific autophagy is important for the timely recovery of mitochondrial function after FI. Following FI, there is a significant increase in several mitochondrial-specific autophagy-related protein contents including dynamin-related protein 1 (Drp1), BCL1 interacting protein (BNIP3), Pink1, and Parkin (similar to 2-fold, P < 0.02). Also, mitochondrial-enriched fractions from H muscles showed microtubule-associated protein light chain B1 (LC3)II colocalization suggesting autophagosome assembly around the damaged mitochondrial. Unc-51 like autophagy activating kinase (Ulk1) is considered necessary for mitochondrial-specific autophagy and herein we utilized a mouse model with Ulk1 deficiency in adult skeletal muscle (myogenin-Cre). While Ulk1 knockouts had contractile weakness compared with littermate controls (-27%, P < 0.02), the recovery of mitochondrial function was not different, and this may be due in part to a partial rescue of Ulk1 protein content within the regenerating muscle tissue of knockouts from differentiated satellite cells in which Ulk1 was not genetically altered via myogenin-Cre. Lastly, autophagy flux was significantly less in injured versus uninjured muscles (-26%, P < 0.02) despite the increase in autophagy-related protein content. This suggests autophagy flux is not upregulated to match increases in autophagy machinery after injury and represents a potential bottleneck in the clearance of damaged mitochondria by autophagy.