Changes and related mechanism of mitophagy- and apoptosis-related protein expressions after spinal cord injury in rats
10.3760/cma.j.cn501098-20231027-00247
- VernacularTitle:大鼠脊髓损伤后线粒体自噬和凋亡相关蛋白的表达变化及其发生机制
- Author:
Yiqun DING
1
;
Tengfei MAO
;
Xigong LI
;
Xiaohui YANG
;
Qin ZHANG
Author Information
1. 长治医学院研究生院，长治 046000
- Keywords:
Spinal cord injuries;
Mitochondria;
Autophagy;
Apoptosis
- From:
Chinese Journal of Trauma
2023;39(12):1118-1129
- CountryChina
- Language:Chinese
-
Abstract:
Objective:To explore the changes of mitophagy- and apoptosis-related protein expressions after spinal cord injury in rats and its related mechanism.Methods:Ninety-six healthy female SD rats were divided into sham surgery group ( n=48) and spinal cord injury group ( n=48) according to the random number table. Each group was divided into six time points of 1, 3, 7, 14, 21 and 28 days with 8 rats at each time point. In the sham surgery group, the T 8-9 spinous processes and vertebral plates were removed without damage to the spinal cord; in the spinal cord injury group, the spinal cord injury model was established using Allen′s method. At each post-injury time point in two groups, BBB score was used to evaluate the motor function of the rats; HE staining was used to observe the histopathological changes of the spinal cord; immunofluorescence was used to observe the co-localized positive cells of the voltage-dependent anion channel protein 1 (VDAC1) with microtubule-associated protein 1 light chain 3 (LC3) II, E3 ubiquitin ligase (Parkin), and polyubiquitin-binding protein (p62); Western blotting was used to observe expressions of the mitochondrial LC3 II/LC3 I, cytoplasmic Parkin, mitochondrial Parkin, cytoplasmic p62, mitochondrial p62, cytoplasmic apoptotic proteins (Bax), mitochondrial Bax, cytoplasmic cytochrome C (Cyt C), and mitochondrial Cyt C. Results:(1) Compared with the sham surgery group [(21.00±0.00)points at all time points], the BBB scores in the spinal cord injury group were (0.94±0.50)points, (1.69±0.70)points, (4.13±0.99)points, (11.81±1.03)points, (15.06±1.12)points and (18.38±0.83)points at 1, 3, 7, 14, 21 and 28 days after injury, respectively ( P<0.01). (2) Compared with the sham surgery group, the structure in the spinal cord injury group was significantly disrupted at 1 and 3 days after injury, when a large number of hemorrhagic foci, inflammatory cell infiltration, neuronal swelling, and cavity formation were observed. At 7 and 14 days after injury, the number of hemorrhagic foci was markedly reduced compared with the earlier period, when swollen neuronal cytosols, inflammatory cell infiltration and a large number of cavities were found. At 21 and 28 days after injury, a large number of cells were seen to be involved in the repair and the arrangement of cells was disorganized. (3) Compared with the sham surgery group, the number of co-localized positive cells of VDAC1 with LC3 II, Parkin and p62 separately in the spinal cord injury group, markedly increased at 1 and 3 days after surgery, and gradually decreased after that. (4) In the sham surgery group and at 1, 3, 7, 14, 21 and 28 days after injury in the spinal cord injury group, the mitochondrial LC3 II/LC3 I expression levels were 0.56±0.05, 1.00±0.05, 1.19±0.11, 0.86±0.05, 0.80±0.08, 0.66±0.13 and 0.51±0.11, respectively; the cytoplasmic Parkin expression levels were 0.80±0.13, 0.47±0.08, 0.29±0.06, 0.57±0.07, 0.70±0.05, 0.97±0.09 and 0.88±0.12, respectively; the mitochondrial Parkin expression levels were 0.67±0.09, 1.07±0.18, 1.27±0.15, 0.82±0.12, 0.59±0.09, 0.53±0.13 and 0.57±0.14, respectively; the cytoplasmic p62 expression levels were 1.25±0.08, 1.04±0.04, 0.94±0.05, 1.09±0.05, 1.19±0.06, 1.20±0.04 and 1.27±0.05, respectively; the mitochondrial p62 expression levels were 0.61±0.06, 0.88±0.07, 1.09±0.09, 0.98±0.07, 0.70±0.08, 0.68±0.08 and 0.60±0.09, respectively; the cytoplasmic Bax expression levels were 0.92±0.08, 0.67±0.07, 0.36±0.08, 0.48±0.08, 0.69±0.06, 0.88±0.11 and 0.94±0.08, respectively; the mitochondrial Bax expression levels were 0.57±0.04, 0.74±0.04, 0.91±0.05, 0.76±0.05, 0.63±0.08, 0.61±0.05 and 0.57±0.05, respectively; the cytoplasmic Cyt C expression levels were 0.28±0.05, 0.81±0.07, 1.12±0.08, 0.64±0.07, 0.67±0.13, 0.60±0.11 and 0.37±0.06, respectively; and the mitochondrial Cyt C expression levels were 1.02±0.07, 0.91±0.14, 0.37±0.07, 0.73±0.06, 0.91±0.11, 0.95±0.13 and 1.10±0.15, respectively. Compared with the sham surgery group, in the spinal cord injury group mitochondrial LC3II/LC3I had the highest expression level at 3 days after injury; cytoplasmic Parkin had the lowest expression level at 3 days after injury; mitochondrial Parkin had the highest expression level at 3 days after injury; cytoplasmic p62 had the lowest expression level at 3 days after injury; mitochondrial p62 had the highest expression level at 3 days after injury; cytoplasmic Bax had the lowest expression level at 3 days after injury; mitochondrial Bax had the highest expression level at 3 days after injury; cytoplasmic Cyt C had the highest expression level at 3 days after injury; and mitochondrial Cyt C had the lowest expression level at 3 days after injury. Conclusion:Mitochondrial autophagy and apoptosis are enhanced after spinal cord injury in rats, and the potential mechanism may be associated with the transfer of Parkin and P62 from the cytoplasm to the damaged mitochondria for enhanced mitophagy and the release of a large amount of Cyt C from the mitochondria caused by the transfer of Bax from the cytoplasm to the damaged mitochondria for enhanced apoptosis.
