硝酸甘油及线粒体乙醛脱氢酶对心肌保护作用的研究进展

缺血预处理是预防心脏缺血再灌注损伤有效的方法之一,近来发现:药物预处理也能够模拟缺血预处理的机制,减轻心肌缺血再灌注损伤。硝酸甘油预处理能保护心肌,减轻缺血再灌注损伤;其机制与预处理保护机制中线粒体内信号通路有关。线粒体乙醛脱氢酶是硝酸甘油的主要代谢酶,其本身活性的增高也能减轻心肌缺血再灌注损伤。     

微小RNA对缺血再灌注损伤心肌线粒体作用的研究进展

心肌缺血再灌注损伤是造成心肌结构损伤、功能障碍的一种病理生理过程,进一步发展会导致级联的多器官功能障碍。线粒体是一种结构功能复杂且对外界环境反应敏感的细胞器,其稳态的维持依赖于正常形态、功能及数量的相对稳定状态。线粒体质量与代谢异常和心血管疾病尤其是心肌缺血再灌注损伤的发生密切相关。微小RNA是近年来研究较多的在缺血再灌注损伤心肌线粒体保护中具有重要作用的调控因子。本文通过微小RNA对心肌缺血再灌注损伤时线粒体形态、功能、线粒体自噬和线粒体DNA几个方面的调控机制与相关前沿进展进行综述,为微小RNA参与缺血再灌注心肌线粒体损伤的后续研究提供一定的理论依据。     

牛磺酸在大鼠缺血再灌注过程中对肝线粒体的保护作用

目的：观察缺血再灌注过程中线粒体的变化和牛磺酸的保护作用。方法：实验动物分为3组，假处理组（对照）组，阻断组，阻断＋牛磺酸组（保护组）。线粒体分离后测定呼吸功能，琥珀酸氧化酶，NADH氧经酶，细胞色素C氧化酶活性，MDA，GSH含量，钙，镁含量和游离钙的浓度。结果：肝缺血再灌注以后，线粒体呼吸功能和氧化磷酸化功能显著降低，引起线粒体脂质过氧化损伤，并可造成线粒体内GSH下降，使线粒体抗氧化系统活性下降；同时可引起线粒体内钙积聚，游离钙浓度明显升高以及镁的丢失。这些结果说明线粒体能量代谢障碍是缺血再灌注损伤的始动环节，而氧自由基是造成损伤的主要因素。牛磺酸对缺血再灌注损伤过程中线粒体损伤的各个环节均起保护作用。结论：研究表明牛磺酸作为自由基清除剂在体内可能具有非常重要的生理学作用。     

心肌缺血再灌注损伤中的线粒体相关细胞器串扰

细胞器损伤是导致心肌缺血再灌注损伤的重要因素。这种损伤会导致线粒体及相关细胞器的功能改变。线粒体与其他细胞器的串扰同样影响心脏缺血再灌注损伤的发生发展,例如线粒体相关内质网膜使得线粒体和内质网“无缝连接”,调节线粒体和内质网之间的细胞器和代谢物(包括离子、脂质和蛋白质)交换,从而影响心肌缺血再灌注损伤。然而,线粒体与相关细胞器串扰是触发心肌缺血再灌注损伤的关键因素,目前相关报道有限。因此,该文阐述了线粒体与内质网、溶酶体和细胞核串扰在心肌缺血再灌注损伤中的作用,旨在为靶向线粒体与其他细胞器的串扰治疗心肌缺血再灌注损伤的研究提供一定的理论依据。     

局灶性缺血再灌注大鼠脑线粒体损伤的实验研究

采用大鼠大脑中动脉缺血（MCAO）再灌注模型，观察缺血再灌注不同时相（分为五组）脑线粒体损伤的变化规律。结果为脑缺血再灌注后线粒体基质游离钙含量（MCa）明显高于假手术组Na^＋、K^＋-ATP酶、Ca^2＋、Mg^＋-ATP酶活性明显下降，且随时间的延长下降明显；再灌注0．5h的MDA和SOD均元明显变化，再灌注1h后线粒体MDA含量明显升高，SOD活性明显下降。说明脑缺血再灌注线粒体损伤与线粒体钙超载及线粒体内膜氧化磷酸化有关。     

线粒体连接蛋白43参与缺血后处理对兔急性心肌缺血再灌注损伤的保护作用

目的 探讨线粒体连接蛋白43(connexin43,Cx43)和线粒体ATP敏感性钾通道(mitoK_(ATP)~+)在缺血后处理保护兔心肌缺血再灌注损伤中的作用.方法 新西兰大白兔64只,建立心肌缺血再灌注模型,给予冠状动脉左前降支30 min缺血,240 min再灌注.随机分为4组,每组16只:假手术组、缺血再灌注组、缺血后处理组和5-羟葵酸加缺血后处理组.测定血浆磷酸肌酸激酶同工酶(CK-MB),肌钙蛋白I(cTnI)含量以及心肌梗死面积,采用电子显微镜观测心肌线粒体结构变化,Western blot检测线粒体Cx43蛋白表达.结果 缺血后处理组心肌梗死面积为(19.1±3.9)%,明显低于缺血再灌注组(35.7±5.8)%,P＜0.01.再灌注4 h末血浆CK-MB与cTnI活性,缺血后处理组明显低于缺血再灌注组和5-羟葵酸加缺血后处理组(P＜0.01).与假手术组比较,其他各组线粒体均损伤明显(P均＜0.01);缺血后处理组线粒体损伤程度轻于缺血再灌注组(P＜0.01);缺血后处理组线粒体损伤程度明显轻于5-羟葵酸加缺血后处理组(P＜0.01).缺血再灌注组和5-羟葵酸加缺血后处理组线粒体Cx43蛋白表达均显著低于假手术组(P均＜0.05);缺血后处理组心肌线粒体Cx43蛋白表达明显高于缺血再灌注组(P＜0.05);缺血后处理组心肌线粒体Cx43蛋白表达明显高于5-羟葵酸加缺血后处理组(P＜0.05).结论 线粒体Cx43可能参与了缺血后处理的心肌保护作用,其机制可能与mitoK_(ATP)~+有关.     

姜黄素对缺血再灌注损伤大鼠心肌线粒体呼吸链的影响

目的 探讨姜黄素对心肌缺血再灌注损伤大鼠心肌梗死面积及心肌线粒体呼吸链的影响。方法 采用健康雄性Wister大鼠（n=24）建立Langendorff离体心脏灌注模型,分为3组,正常对照组、缺血再灌注组和姜黄素预处理组。正常对照组持续灌注90 min;缺血再灌注组全心缺血30 min,再灌注60 min;姜黄素预处理组加入姜黄素（0.2 mmol/L）后,全心缺血30 min,再灌注60 min。再灌注结束时,TTC染色观察心肌梗死面积,应用紫外分光光度法测定缺血再灌注后心肌线粒体呼吸链复合体Ⅰ、Ⅳ的活性。结果[结果部分应列举主要数据,并修改英文摘要] ①缺血再灌注组心肌坏死面积约为26.9±2.5%。经姜黄素预处理后,心肌梗死面积为21.8±2.2%,较缺血再灌注组明显降低,差异有统计学意义;②缺血再灌注组心肌线粒体呼吸链复合体Ⅰ、Ⅳ活性分别为0.453±0.069、0.050±0.005,姜黄素预处理组心肌线粒体呼吸链复合体Ⅰ、Ⅳ活性分别为0.565±0.071、0.059±0.004,较缺血再灌注组均显著增加,差异有统计学意义（P<0.05）。结论 姜黄素预处理能够缩小心肌梗死面积,同时增加线粒体呼吸链复合体Ⅰ、Ⅳ的活性,从而对缺血再灌注损伤心肌起保护作用。     

线粒体功能障碍与心肌缺血再灌注损伤

<正>近年来,随着溶栓治疗、冠状动脉旁路移植术、PCI等在临床的广泛应用,再灌注损伤越来越受到广泛的关注。心肌缺血再灌注损伤是指经历一定时间缺血的心肌组织在恢复血流灌注后损伤加重的现象,包括心律失常、心肌收缩功能下降和再灌注心肌不可逆损伤等。在再灌注损伤过程中,线粒体(mitochondria)功能障碍是一个非常重要的病理机制,包括线粒体ATP生成减少、Ca2+过荷、活性氧大量产生     

泛素与非泛素依赖途径的线粒体自噬对心肌损伤的影响

缺血再灌注损伤(ischemia reperfusion injury,IRI)是急性心肌梗死、冠心病、中风等心血管疾病发生损伤的核心病理过程[1],是在组织或器官缺氧的基础上由于血流的再灌注导致细胞损伤加重的现象.缺血再灌注损伤由多种因素介导,包括线粒体钙超载、活性氧(reactive oxygen species,...     

辣椒素减轻肾缺血再灌注损伤的线粒体相关机制

目的探讨辣椒素对大鼠肾缺血再灌注损伤的保护作用及线粒体相关作用机制。方法将50只雄性SD大鼠分成假手术组、肾缺血再灌注损伤组和辣椒素低、中、高剂量组。采用夹闭双侧肾蒂构建肾缺血再灌注损伤模型。肾缺血45 min,再灌注24 h,过量麻醉法处死大鼠,收集肾脏和血清。检测血清肌酐(SCr)、血尿素氮(BUN)、肾脏组织病理形态和细胞凋亡,测定线粒体三磷酸腺苷(ATP)和丙二醛(MDA)含量以及Ca~(2+)-ATP酶、Na~+-K~+-ATP酶、过氧化氢酶(CAT)、谷胱甘肽过氧化物酶(GPx)和超氧化物歧化酶(SOD)活性。结果辣椒素干预可减少SCr和BUN含量,降低肾组织病理改变和细胞凋亡,增加线粒体Ca~(2+)-ATP酶、Na~+-K~+-ATP酶、CAT、GPx和SOD酶活性以及ATP的含量,但减少MDA的水平。结论辣椒素对肾缺血再灌注损伤有保护作用,其作用呈浓度效应,机制与抑制线粒体脂质过氧化相关。     

Inheritance of mitochondrial DNA in humans: implications for rare and common diseases

The first draft human mitochondrial DNA (mtDNA) sequence was published in 1981, paving the way for two decades of discovery linking mtDNA variation with human disease. Severe pathogenic mutations cause sporadic and inherited rare disorders that often involve the nervous system. However, some mutations cause mild organ‐specific phenotypes that have a reduced clinical penetrance, and polymorphic variation of mtDNA is associated with an altered risk of developing several late‐onset common human diseases including Parkinson’s disease. mtDNA mutations also accumulate during human life and are enriched in affected organs in a number of age‐related diseases. Thus, mtDNA contributes to a wide range of human pathologies. For many decades, it has generally been accepted that mtDNA is inherited exclusively down the maternal line in humans. Although recent evidence has challenged this dogma, whole‐genome sequencing has identified nuclear‐encoded mitochondrial sequences (NUMTs) that can give the false impression of paternally inherited mtDNA. This provides a more likely explanation for recent reports of ‘bi‐parental inheritance’, where the paternal alleles are actually transmitted through the nuclear genome. The presence of both mutated and wild‐type variant alleles within the same individual (heteroplasmy) and rapid shifts in allele frequency can lead to offspring with variable severity of disease. In addition, there is emerging evidence that selection can act for and against specific mtDNA variants within the developing germ line, and possibly within developing tissues. Thus, understanding how mtDNA is inherited has far‐reaching implications across medicine. There is emerging evidence that this highly dynamic system is amenable to therapeutic manipulation, raising the possibility that we can harness new understanding to prevent and treat rare and common human diseases where mtDNA mutations play a key role.     

线粒体及其蛋白质质量控制失调与动脉粥样硬化的关系

线粒体是哺乳动物细胞内重要的细胞器,作为细胞能量代谢和细胞死亡的调控中心,其功能异常会导致多种疾病的发生与发展。 线粒体功能依赖于线粒体蛋白质组的完整性和稳态,因此线粒体蛋白质质量控制系统对于维持线粒体稳态和机体健康十分重要。当线粒体及其蛋白质质量控制系统出现异常时,会直接损伤线粒体并出现异常线粒体蛋白堆积,发生细胞内环境紊乱,甚至细胞功能障碍,进而影响动脉粥样硬化性疾病的发生与发展。文章回顾了线粒体及其蛋白质质量控制系统在动脉粥样硬化性疾病发生发展中的作用,并对该领域未来的发展前景和挑战进行展望,以期为寻找与动脉粥样硬化性疾病密切相关的特异性线粒体蛋白提供线索。     

PTEN-inducible kinase 1 (PINK1)/Park6 is indispensable for normal heart function

Oxidative stress is caused by an imbalance between reactive oxygen species (ROS) production and the ability of an organism to eliminate these toxic intermediates. Mutations in PTEN-inducible kinase 1 (PINK1) link mitochondrial dysfunction, increased sensitivity to ROS, and apoptosis in Parkinson's disease. Whereas PINK1 has been linked to the regulation of oxidative stress, the exact mechanism by which this occurs has remained elusive. Oxidative stress with associated mitochondrial dysfunction leads to cardiac dysfunction and heart failure (HF). We hypothesized that loss of PINK1 in the heart would have deleterious consequences on mitochondrial function. Here, we observed that PINK1 protein levels are markedly reduced in end-stage human HF. We also report that PINK1 localizes exclusively to the mitochondria. PINK1(-/-) mice develop left ventricular dysfunction and evidence of pathological cardiac hypertrophy as early as 2 mo of age. Of note, PINK1(-/-) mice have greater levels of oxidative stress and impaired mitochondrial function. There were also higher degrees of fibrosis, cardiomyocyte apoptosis, and a reciprocal reduction in capillary density associated with this baseline cardiac phenotype. Collectively, our in vivo data demonstrate that PINK1 activity is crucial for postnatal myocardial development, through its role in maintaining mitochondrial function, and redox homeostasis in cardiomyocytes. In conclusion, PINK1 possesses a distinct, nonredundant function in the surveillance and maintenance of cardiac tissue homeostasis.     

From the Cover: Impaired mitochondrial transport and Parkin-independent degeneration of respiratory chain-deficient dopamine neurons in vivo

Mitochondrial dysfunction is heavily implicated in Parkinson disease (PD) as exemplified by the finding of an increased frequency of respiratory chain-deficient dopamine (DA) neurons in affected patients. An inherited form of PD is caused by impaired function of Parkin, an E3 ubiquitin ligase reported to translocate to defective mitochondria in vitro to facilitate their clearance. We have developed a reporter mouse to assess mitochondrial morphology in DA neurons in vivo and show here that respiratory chain deficiency leads to fragmentation of the mitochondrial network and to the formation of large cytoplasmic bodies derived from mitochondria. Surprisingly, the dysfunctional mitochondria do not recruit Parkin in vivo, and neither the clearance of defective mitochondria nor the neurodegeneration phenotype is affected by the absence of Parkin. We also show that anterograde axonal transport of mitochondria is impaired in respiratory chain-deficient DA neurons, leading to a decreased supply of mitochondria to the axonal terminals.     

Early deficits in synaptic mitochondria in an Alzheimer's disease mouse model

Synaptic dysfunction and the loss of synapses are early pathological features of Alzheimer's disease (AD). Synapses are sites of high energy demand and extensive calcium fluctuations; accordingly, synaptic transmission requires high levels of ATP and constant calcium fluctuation. Thus, synaptic mitochondria are vital for maintenance of synaptic function and transmission through normal mitochondrial energy metabolism, distribution and trafficking, and through synaptic calcium modulation. To date, there has been no extensive analysis of alterations in synaptic mitochondria associated with amyloid pathology in an amyloid β (Aβ)-rich milieu. Here, we identified differences in mitochondrial properties and function of synaptic vs. nonsynaptic mitochondrial populations in the transgenic mouse brain, which overexpresses the human mutant form of amyloid precursor protein and Aβ. Compared with nonsynaptic mitochondria, synaptic mitochondria showed a greater degree of age-dependent accumulation of Aβ and mitochondrial alterations. The synaptic mitochondrial pool of Aβ was detected at an age as young as 4 mo, well before the onset of nonsynaptic mitochondrial and extensive extracellular Aβ accumulation. Aβ-insulted synaptic mitochondria revealed early deficits in mitochondrial function, as shown by increased mitochondrial permeability transition, decline in both respiratory function and activity of cytochrome c oxidase, and increased mitochondrial oxidative stress. Furthermore, a low concentration of Aβ (200 nM) significantly interfered with mitochondrial distribution and trafficking in axons. These results demonstrate that synaptic mitochondria, especially Aβ-rich synaptic mitochondria, are more susceptible to Aβ-induced damage, highlighting the central importance of synaptic mitochondrial dysfunction relevant to the development of synaptic degeneration in AD.     

A common mitochondrial DNA variant is associated with insulin resistance in adult life

Summary Mitochondrial DNA is maternally inherited. Mitochondrial DNA mutations could contribute to the excess of maternal over paternal inheritance of non-insulin-dependent diabetes mellitus (NIDDM). We therefore investigated the relationship between this variant, insulin resistance and other risk factors in a cohort which had been well characterised with respect to diabetes. Blood DNA was screened from 251 men born in Hertfordshire 1920–1930 in whom an earlier cohort study had shown that glucose tolerance was inversely related to birthweight. The 16 189 variant (T- > C transition) in the first hypervariable region of mitochondrial DNA was detected using the polymerase chain reaction and restriction digestion. DNA analysis showed that 28 of the 251 men (11 %) had the 16 189 variant. The prevalence of the 16 189 variant increased progressively with fasting insulin concentration (p < 0.01). The association was independent of age and body mass index and was present after exclusion of the patients with NIDDM or impaired glucose tolerance. We found that insulin resistance in adult life was associated with the 16 189 variant. This study provides the first evidence that a frequent mitochondrial variant may contribute to the phenotype in patients with a common multifactorial disorder. [Diabetologia (1998) 41: 54–58] Received: 20 May 1997 and in revised form: 7 August 1997     

线粒体功能障碍与血管内皮损伤的研究进展

线粒体功能障碍会导致ATP的生成减少,活性氧的产生增加,被认为是血管内皮损伤的触发因素之一。许多因素与线粒体功能障碍有关,如线粒体DNA突变、线粒体融合与分裂失衡、线粒体自噬受损等。本文综述了线粒体的质量控制过程和线粒体功能障碍在血管内皮损伤中的作用机制,以期为动脉粥样硬化的有效防治提供新的思路。     

Structural basis for recruitment of mitochondrial fission complexes by Fis1

Mitochondrial fission controls mitochondrial shape and physiology, including mitochondrial remodeling in apoptosis. During assembly of the yeast mitochondrial fission complex, the outer membrane protein Fis1 recruits the dynamin-related GTPase Dnm1 to mitochondria. Fis1 contains a tetratricopeptide repeat (TPR) domain and interacts with Dnm1 via the molecular adaptors Mdv1 and Caf4. By using crystallographic analysis of adaptor-Fis1 complexes, we show that these adaptors use two helices to bind to both the concave and convex surfaces of the Fis1 TPR domain. Fis1 therefore contains two interaction interfaces, a binding mode that, to our knowledge, has not been observed previously for TPR domains. Genetic and biochemical studies indicate that both binding interfaces are important for binding of Mdv1 and Caf4 to Fis1 and for mitochondrial fission activity in vivo. Our results reveal how Fis1 recruits the mitochondrial fission complex and will facilitate efforts to manipulate mitochondrial fission.     

Clinical and genetic features of four patients with Pearson syndrome: An observational study

Pearson syndrome (PS) is a multisystem mitochondrial cytopathy arising from deletions in mitochondrial DNA. Pearson syndrome is a sporadic disease that affects the hematopoietic system, pancreas, eyes, liver, and heart and the prognosis is poor. Causes of morbidity include metabolic crisis, bone marrow dysfunction, sepsis, and liver failure in early infancy or childhood. Early diagnosis may minimize complications, but suspicion of the disease is difficult and only mitochondrial DNA gene testing can identify mutations. There is no specific treatment for PS, which remains supportive care according to symptoms; however, hematopoietic stem cell transplantation may be considered in cases of bone marrow failure.We herein describe the clinical and genetic characteristics of four patients with PS. One patient presented with hypoglycemia, two developed pancytopenia, and the final patient had hypoglycemia and acute hepatitis as the primary manifestation. All patients had lactic acidosis. Additionally, all patients showed a variety of clinical features including coagulation disorder, pancreatic, adrenal, and renal tubular insufficiencies. Two patients with pancytopenia died in their early childhood. Our experience expands the phenotypic spectrum associated with PS and its clinical understanding.