Centre of Perinatal Medicine and Health, The Sahlgrenska Academy, University of Gothenburg, 41685 Gothenburg, Sweden.
Institute of Neuroscience and Physiology, The Sahlgrenska Academy, University of Gothenburg, 41390 Gothenburg, Sweden.
Cells. 2022 Apr 1;11(7):1193. doi: 10.3390/cells11071193.
Hypoxia-ischemia (HI) leads to immature brain injury mediated by mitochondrial stress. If damaged mitochondria cannot be repaired, mitochondrial permeabilization ensues, leading to cell death. Non-optimal turnover of mitochondria is critical as it affects short and long term structural and functional recovery and brain development. Therefore, disposal of deficient mitochondria via mitophagy and their replacement through biogenesis is needed. We utilized mt-Keima reporter mice to quantify mitochondrial morphology (fission, fusion) and mitophagy and their mechanisms in primary neurons after Oxygen Glucose Deprivation (OGD) and in brain sections after neonatal HI. Molecular mechanisms of PARK2-dependent and -independent pathways of mitophagy were investigated in vivo by PCR and Western blotting. Mitochondrial morphology and mitophagy were investigated using live cell microscopy. In primary neurons, we found a primary fission wave immediately after OGD with a significant increase in mitophagy followed by a secondary phase of fission at 24 h following recovery. Following HI, mitophagy was upregulated immediately after HI followed by a second wave at 7 days. Western blotting suggests that both PINK1/Parkin-dependent and -independent mechanisms, including NIX and FUNDC1, were upregulated immediately after HI, whereas a PINK1/Parkin mechanism predominated 7 days after HI. We hypothesize that excessive mitophagy in the early phase is a pathologic response which may contribute to secondary energy depletion, whereas secondary mitophagy may be involved in post-HI regeneration and repair.
缺氧缺血（HI）导致线粒体应激介导的未成熟脑损伤。如果受损的线粒体不能被修复，就会导致线粒体通透性增加，从而导致细胞死亡。线粒体的非最佳周转率是至关重要的，因为它会影响短期和长期的结构和功能恢复以及大脑发育。因此，需要通过自噬作用清除有缺陷的线粒体，并通过生物发生来替代它们。我们利用 mt-Keima 报告小鼠来定量氧葡萄糖剥夺（OGD）后原代神经元和新生 HI 后大脑切片中的线粒体形态（分裂、融合）和自噬及其机制。通过 PCR 和 Western blot 在体内研究了 PARK2 依赖性和非依赖性自噬途径的分子机制。使用活细胞显微镜研究线粒体形态和自噬。在原代神经元中，我们发现 OGD 后立即出现原发性分裂波，随后在恢复后 24 小时内自噬明显增加，随后出现第二次分裂阶段。HI 后，自噬立即被上调，随后在 7 天再次出现。Western blot 表明，PINK1/Parkin 依赖性和非依赖性机制（包括 NIX 和 FUNDC1）在 HI 后立即上调，而 PINK1/Parkin 机制在 HI 后 7 天占主导地位。我们假设早期过度的自噬是一种病理反应，可能导致继发性能量耗竭，而继发性自噬可能参与 HI 后的再生和修复。
