The role of Drp1 mediated mitochondrial dynamics balance in sepsis induced cardiomyopathy / 中华急诊医学杂志

Objective:To analyze the effect of inhibiting excessive mitochondrial fission mediated by dynamic related protein 1 (Drp1) on the function of injured cells and mitochondria in the septic myocardium, and to explore the protective effect of maintaining mitochondrial dynamic balance in the pathogenesis of sepsis induced cardiomyopathy(SIC).Methods:Rat H9C2 cardiomyocytes were cultured and stimulated with lipopolysaccharide (LPS) to establish a model of SIC. Mitochondrial division inhibitor 1 (Mdivi-1) was given 30 min before LPS stimulation. They were divided into the control group, LPS stimulated group (LPS), Mdivi-1 control group (Mdivi-1), and LPS+Mdivi-1 intervention group (LPS+Mdivi-1). CCK-8 was used to detect the cell viability, and lactate dehydrogenase (LDH) was used to detect cellular damage. A MitoTracker probe was used to observe mitochondrial morphology by laser scanning confocal microscopy, JC-1 staining was used to detect mitochondrial membrane potential level, a DCFH-DA probe was used to detect total ROS level, and an AnnexinV-FITC/PI probe was used to detect the cell apoptosis ratio. The expression levels of mitochondrial fission protein Drp1 and fusion proteins Optic Atrophy 1(Opa1) and Mitofusin2 (Mfn2) were detected by real-time PCR and Western blot. One-way ANOVA was used to compare the differences between groups, and the LSD- t test was used for pairwise comparisons between groups. Results:Compared with the control group, cell viability, the average length of mitochondria and the mitochondrial membrane potential were decreased, and ROS production, the cell apoptosis rate and LDH were increased in the LPS group (all P<0.05). After Mdivi-1 intervention, compared with the LPS-stimulated group, the cell viability was increased, myocardial cell damage was reduced, the average length of mitochondria was prolonged, mitochondrial dysfunction was alleviated, and the cell apoptosis rate was inhibited in the LPS+Mdivi-1 group (all P<0.05). Conclusions:Mdivi-1 might inhibit mitochondrial fission mediated by Drp1, maintain mitochondrial dynamic balance, alleviate mitochondrial dysfunction and protect myocardial cells from LPS-induced injury.

Mitochondrial Dynamics Mediates Myocardial Energy Metabolism in Coronary Heart Disease due to Blood Stasis / 中国实验方剂学杂志

Objective:To explore the mechanism of energy changes in the three stages of the formation of coronary heart disease due to blood stasis in rat model from the perspective of mitochondrial fusion-fission dynamic changes. Method:Thirty healthy male rats were divided into the blank control group （<italic>n</italic>=6） and model group （<italic>n</italic>=24） using SPSS 21.0 simple random sampling method. The rats in the blank control group were fed an ordinary diet， while those in the model group a high-fat diet. After seven days of adaptive feeding， the rats were treated with intragastric administration of vitamin D₃ （VitD₃） at 300 000 U·kg^-1 and then at 200 000 U·kg^-1 14 d later. The high-fat diet continued for 21 d， and six rats were randomly selected as samples for the pre-stage blood stasis syndrome group， followed by model verification and sampling. The remaining rats continued to receive the high-fat diet for 30 d， and six were randomly selected and categorized into the sub-stage blood stasis syndrome group， followed by model verification and sampling. The rest of rats were classified into the heart blood stasis syndrome group. While continuing the high-fat diet， they were also treated with multipoint subcutaneous injection of isoproterenol （ISO，5 mg·kg^-1） for three consecutive days. One week later， the electrocardiogram （ECG） was recorded for determining whether the modeling was successful and the samples were taken at the same time. The changes in mitochondrial morphology and quantity were observed under a transmission electron microscope. The expression of mitochondrial dynamics-related proteins was measured by Western blot and the cellular localization of related proteins by immunofluorescence assay. Result:The levels of total cholesterol and low-density lipoprotein cholesterol in the pre-stage and sub-stage blood stasis syndrome groups were significantly increased as compared with those in the blank control group （<italic>P</italic><0.05）. The blood rheology index in the pre-stage blood stasis syndrome group was significantly elevated in contrast to that in the blank control group （<italic>P</italic><0.05）. The three-layered membrane of the aorta in the blank group was intact. However， the tunica media of the pre-stage blood stasis syndrome group began to show obvious calcification， with a small number of inflammatory cells adhering to the intima. The subintima and media smooth muscles in the sub-stage blood stasis syndrome group exhibited cavity structures. The three-layered structure of the arterial wall in the heart blood stasis syndrome group was severely damaged. The ECG of the blank control group revealed the regular appearance of P wave，regular QRS waveform （no broadening or deformity）， and no obvious ST-segment depression or elevation. The ECG of the pre-stage blood stasis syndrome group showed no obvious abnormalities as compared with that of the blank control group. In the sub-stage blood stasis syndrome group， the ECG showed an upward trend of the J point and slight ST-segment elevation， with the elevation≤0.1 mV. The ECG in the heart blood stasis syndrome group displayed significant ST-segment depression （>0.1 mV） and J point depression >0.1 mV. The mitochondria in the blank control group were normal in size and morphology， with clear and dense cristae， whereas those in the pre-stage blood stasis syndrome group were fusiform with sparse cristae. Some mitochondria in the sub-stage blood stasis syndrome group were significantly elongated， and even vacuole-like changes were present. In the heart blood stasis syndrome group， the mitochondria were ruptured. As demonstrated by comparison with the blank control group， the expression levels of mitofusin 2 （Mfn2）， dynamin-related protein 1 （Drp1）， and fission protein 1 （Fis1） in the model group were significantly up-regulated （<italic>P</italic><0.05，<italic>P</italic><0.01）. Compared with the pre-stage blood stasis syndrome group， the heart blood stasis syndrome group exhibited down-regulated Mfn2 （<italic>P<</italic>0.05）. Compared with the blank control group and the pre-stage blood stasis syndrome group， the sub-stage blood stasis syndrome group and the heart blood stasis syndrome group displayed down-regulated optic atrophy 1（OPA1） （<italic>P</italic><0.05，<italic>P</italic><0.01）. The Drp1 and Fis1 protein expression declined significantly in the sub-stage blood stasis syndrome group in comparison with that in the pre-stage blood stasis syndrome group （<italic>P</italic><0.05，<italic>P</italic><0.01）. The expression levels of Mfn2 and Drp1 in the heart blood stasis syndrome group were lower than those in the sub-stage blood stasis syndrome group （<italic>P<</italic>0.01）. The comparison with the blank control group showed that Mfn2 and OPA1 were extensively accumulated in mitochondria of both the pre-stage and sub-stage blood stasis syndrome groups， while the red-stained Mfn2 was significantly reduced in the heart blood stasis syndrome group. The Drp1/Fis1 fluorescence was weak in the blank group and the pre-stage blood stasis syndrome group but strong in the sub-stage blood stasis syndrome group and heart blood stasis syndrome group. Conclusion:The cardiomyocyte mitochondria dynamics changes with the change in energy demand of cardiomyocytes. Mfn2 is dominated by fusion effect in the early stage of the formation of coronary heart disease due to blood stasis. With the gradual development of this disease， Mfn2 begins to mediate mitochondrial autophagy. OPA1 plays a role in intimal fusion and cristae integrity. The decreased OPA1 expression is closely related to the accelerated progression of coronary heart disease differentiated into blood stasis syndrome. The process by which Drp1 and Fis1 separate damaged mitochondria to prepare for mitochondrial autophagy contributes to alleviating the imbalance between the energy demand and supply of human body.

Effect of the regulation of mitochondrial dynamics on renal ischemia-reperfusion injury / 器官移植

Ischemia-reperfusion injury (IRI) is one of the main causes of early graft dysfunction after renal transplantation. In China, organ transplantation has entered into the era of organ donation after citizen's death. The increased risk of cardiopulmonary resuscitation, prolonged hypoperfusion time and warm ischemia time of donors may lead to IRI of the graft, and affect the short- and long-term clinical prognosis of the recipient and graft. Under IRI and other stress conditions, the mechanism of mitochondrial dynamics, mainly manifested by dynamic regulation of mitochondrial division and fusion, exert critical effect upon the biological function of mitochondria. Cell apoptosis caused by mitochondrial injury is the key event leading to acute kidney injury, which is mainly manifested by the imbalance of the regulatory mechanism of mitochondrial dynamics. In this article, the research progress on the regulatory mechanism of mitochondrial dynamics on renal IRI was reviewed, aiming to provide reference for improving the clinical outcomes of renal transplantation.

Effects of Acupuncture on Behaviors, Expressions of Fis1 and OPA1, and Mitochondrial Ultrastructure of Mice Model of Alzheimer Disease / 中国中医药信息杂志

Objective To observe the effects of acupuncture on the behaviors and the expressions of Fis1 and OPA1, as well as mitochondrial ultrastructure in the hippocampus of mice with Alzheimer disease (AD); To explore the mechanism of action of acupuncture for AD.Methods Forty male SAMP8 mice were randomly divided into acupuncture group and model group, with 20 mice in each group. Another 20 male natural aging mice with the same age (SAMR1 mice) were set as the normal group. Acupuncture group chose Shenshu, Baihui, Xuehai and Geshu for intervention. 8 weeks later, Morris water maze was used to test the mice behaviors, and then hippocampus organization was taken. Western blot was used to detect the expressions of Fis1 and OPA1 and mitochondrial ultrastructure in hippocampal neurons of mice was observed by transmission electron microscopy.Results Compared with the model group, the escape latency of acupuncture group was significantly shortened (P<0.05), and the stay time in the former platform quadrant and former platform crossing times were significantly increased (P<0.05). The expression of Fis1 in the hippocampus of acupuncture group decreased significantly (P<0.05), while the expression of OPA1 increased significantly (P<0.05). The mitochondrial ultrastructure in hippocampus in the acupuncture group was effectively improved, and the mitochondrial surface density and body density were both increased in the acupuncture group compared with the model group (P<0.05).Conclusion Acupuncture may play a potential therapeutic role in AD by decreasing the expression of Fis1, increasing the expression of OPA1, recovering the injury of mitochondrial ultrastructure.

Effect of extraction of saffron crocus on mitochondrial dynamics in ischemia/reperfusion rats / 中国药理学通报

Aim To investigate the protection mecha-nism of the extraction of the saffron crocus in ischemia/reperfusion rats. Methods Hematoxylin-eosin stai-ning, electron microscopy, and neurological assess-ments were performed in a transient middle cerebral ar-tery occlusion ( tMCAO ) rat model. The role of dy-namin-related protein 1 ( Drp1 ) and optic atrophy 1 ( Opa1 ) , the two key regulators of mitochondrial fis-sion and fusion in ischemic brain damage in vivo were observed. Results In ischemia/reperfusion rats, the extraction of the saffron crocus increased the level of protein Opa1 and decreased the level of protein Drp1 . Conclusions Inhibition of Drp1 and promotion of Opa1 , which means to maintain balancing mitochondri-al dynamics, is proposed as an efficient strategy for neuroprotection against ischemic brain damage.

A novel mutation in a case of dominant optic atrophy.

A 39‑year‑old healthy woman presented for decreased vision at distance and near for 4 years. She also noted a decrease in her color vision. Her best‑corrected visual acuities were 20/70 in each eye. Her visual fields were abnormal, and she had bilateral sluggish pupils, impaired color vision, and optic disc pallor. The magnetic resonance imaging of the brain, heavy metal screen, autoimmune work‑up, B12, B6, folate, erythrocyte sedimentation rate, rapid plasma reagin, and Lyme titer were all normal. Optical coherence tomography of the macula and electroretinogram were normal; the visual evoked potential was unrecordable in both eyes. She denied a family history of similar ocular issues, and genotyping of the OPA1 gene revealed a novel previously unreported mutation at IVS12+10T >C.

Progression of autosomal dominant optic atrophy / 中华实验眼科杂志

Autosomal dominant optic atrophy(ADOA),also called Kjer-type optic atrophy,is the most decrease of visual acuity,color vision deficit,visual field defects,and it is also characterized by temporal pallor of the optic disc.Deafness,cataract,ophthalmoplegia,ptosis and so on,can also accompany ADOA.Up to now,it has been verified that four known genetic loci are associated with ADOA,including OPA1(3q28-29),OPA3(19q13.2-13.3),OPA4(18q12.2-12.3)and OPA5(22q12.1-13.1).The OPA1 and OPA3 genes have been cloned.But genotypephenotype correlations and pathogenic mechanisms of ADOA are not very clear.The recent researches about clinical features,relevant candidate gene and loci,differentiation diagnosis were reviewed.