线粒体融合-分裂与心力衰竭

线粒体融合、分裂及二者之间的动态转换,统称为线粒体动力学。线粒体融合-分裂参与线粒体的多种生物学功能,包括能量代谢、活性氧、Ca2+稳态和细胞死亡过程的调节等。心脏发育、心肌能量代谢及心肌细胞内离子稳态等与线粒体融合-分裂平衡密切相关,其失衡能引起心肌细胞功能紊乱,导致心肌细胞受损甚至死亡,最终发生心力衰竭。药物靶向重建线粒体融合-分裂平衡可能为慢性心力衰竭的治疗提供新的思路和策略。     

脓毒症心肌线粒体改变与干预的研究进展

约50%的脓毒症患者合并心脏收缩功能降低和心输出量减少,约11.4%患者甚至出现心功能衰竭。目前认为,脓毒症时心肌线粒体形态和功能的改变是心肌收缩功能降低的重要原因。长期以来人们对脓毒症时的心肌线粒体改变与干预的基础和临床研究开展了大量的实验。本文就近年来国内外有关脓毒症时心肌线粒体结构、功能、自噬作用、凋亡作用的改变与干预方面的研究进展做了总结论述。     

线粒体的融合、分裂与炎症反应研究进展

正线粒体不仅是ATP的主要供应场所,而且参与许多细胞的信号转导过程,如Ca~(2+)内稳态、凋亡、活性氧簇(reactive oxygen species,ROS)的产生等。线粒体作为一种动态的细胞器,可以不停地进行融合与分裂运动,这种融合与分裂运动称为线粒体动力学(mitochondrial dynamics)。在正常情况下,线粒体的融合与分裂处于动态平衡状态,一旦该平衡破坏     

硫氢化钠减轻高糖高脂诱导的大鼠心肌细胞系H9C2线粒体损伤

目的 探究高糖高脂条件下硫氢化钠(NaHS)调控大鼠心肌细胞系H9C2线粒体融合/分裂的作用机制。方法 采用db/db小鼠及高糖高脂(40 mmol/L葡萄糖+200μmol/L棕榈酸盐+200μmol/L油酸)处理的H9C2为2型糖尿病动物和细胞模型，分别用硫氢化钠(H₂S供体)(100μmol/L)和帕金森病相关蛋白7(DJ-1) siRNA处理48 h干预模型。心动超声和电镜分别观察心脏功能和心肌超微结构；Western blot检测CSE,Mfn2,DJ-1蛋白的表达；用MitoTracker Green探针染色观察线粒体形态变化。结果 与正常对照组比高糖高脂组中线粒体分裂增加，线粒体融合降低，Mfn2的表达下降(P<0.05), Fis1表达增加(P<0.05);NaHS上调DJ-1的表达，减轻线粒体的分裂和增加Mfn2的表达水平，降低Fis1的表达。NaHS恢复db/db小鼠的心肌收缩力，减轻心肌线粒体肿胀及分裂。结论 NaHS可能通过促进线粒体融合，减轻线粒体损伤。     

脓毒症时心肌能量代谢障碍机制的研究进展

心肌能量代谢障碍是导致脓毒症时心肌损伤的重要因素,但其确切的机制目前尚未完全阐明。正常情况下,线粒体是心肌能量代谢的主要场所,脂肪酸和葡萄糖氧化代谢生成的三磷酸腺苷是心脏能量的主要来源。脓毒症时,线粒体结构损伤、呼吸功能障碍、Ca2+超载、生物合成改变、自噬以及脂肪酸摄取、转运、氧化减少和葡萄糖代谢异常等导致了心肌能量代谢障碍,进而引起心肌结构损伤和功能障碍。本文主要对线粒体结构和功能异常、糖脂质代谢紊乱与脓毒症心肌能量代谢障碍关系的研究进展进行了综述。     

白藜芦醇干预运动性疲劳模型大鼠线粒体动力学的变化

背景：白藜芦醇是一种存在于葡萄、花生、藜芦等植物中的多酚化合物,是健康食物增补剂的一种。已有研究表明补充白藜芦醇能缓解运动性疲劳,但其具体机制仍不明确,此次研究通过线粒体动力学角度对其机制进行研究。目的：探讨补充白藜芦醇对运动性疲劳大鼠线粒体动力学的影响。方法：48只SD雄性大鼠随机分为空白对照组、白藜芦醇组、运动组和运动+白藜芦醇组,每组12只。运动+白藜芦醇组与运动组同时进行6周负重5%游泳训练,60 min/次,每周6 d。运动+白藜芦醇组在运动后1 h给予白藜芦醇50 mg/kg灌胃,白藜芦醇组只给予白藜芦醇50 mg/kg灌胃,空白对照组与运动组正常饲养,每天同体积溶剂灌胃。末次运动后24 h取材,测定血浆中尿素氮、丙二醛浓度和超氧化物歧化酶活性,骨骼肌中线粒体融合相关因子线粒体融合蛋白1、线粒体融合蛋白2、视神经萎缩蛋白1和分裂相关因子线粒体动力相关蛋白1、线粒体分裂蛋白1的基因表达。结果与结论：(1)与空白对照组相比,运动组血浆中尿素氮、丙二醛浓度明显升高(P <0.05,P <0.05),超氧化物歧化酶活性明显降低(P <0.05);与运动组相比,运动...     

红景天干预可改善大强度运动小鼠骨骼肌细胞线粒体自噬及融合-分裂等功能

文题释义： 自噬：指从粗面内质网的无核糖体附着区脱落的双层膜包裹部分胞质和细胞内需降解的细胞器、蛋白质等成分形成自噬体(autophagosome),并与溶酶体融合形成自噬溶酶体,降解其所包裹的内容物,以实现细胞本身的代谢需要和某些细胞器的更新。自噬广泛存在于人体的正常细胞和恶性肿瘤细胞中。 线粒体融合-分裂：线粒体是一种高度动态变化的细胞器,在细胞中不断融合与分裂,形成紧密连接的线粒体网络。这种融合与分裂的变化主要通过在线粒体融合、分裂蛋白的精确控制下,线粒体可在不断变化的生理环境中做出迅速准确的反应,这对于线粒体的遗传以及维持其功能至关重要。 背景：超负荷量的运动会引起体内氧化活性物质大量堆积从而损害骨骼肌细胞,而线粒体在运动过程能量代谢中具有关键作用。研究表明,红景天可以减少肌组织脂质过氧化水平,保护受损内皮细胞。 目的：探讨红景天通过调节线粒体功能改善大强度运动小鼠骨骼肌细胞的功能。 方法：实验方案经西安石油大学伦理委员会批准。选择40只SPF级BALB/c小鼠,根据干预措施的不同,将小鼠分为空白对照组、单纯运动组、红景天对照组、红景天运动干预组。①空白对照组：不进行运动;②单纯运动组：采用生理盐水灌胃后,进行大强度运动;③红景天对照组：将红景天与生理盐水悬浊液灌胃,不运动;④红景天运动干预组：红景天干预措施同红景天对照组,运动方案同单纯运动组。以上各组干预措施均为每天1次,连续28 d。观察小鼠的体质量、前肢握力、力竭时间;Western Blot检测骨骼肌锰超氧化物歧化酶蛋白、p53蛋白、线粒体起源、自噬启动相关蛋白表达;RT-qPCR检测骨骼肌Mfn-1、Mfn-2、Opa-1、Drp-1、fis-1 mRNA表达。 结果与结论：①从第2周开始,单纯运动组小鼠前肢握力显著低于其他3组(P < 0.05),但空白对照组、红景天对照组与红景天运动干预组之间,小鼠前肢握力始终无明显差异(P > 0.05);②第3,4周时,单纯运动组小鼠负重游泳训练力竭时间均显著短于红景天运动干预组(P < 0.05);③单纯运动组小鼠骨骼肌细胞内的锰超氧化物歧化酶、p53蛋白表达显著高于其他组小鼠(P < 0.05),红景天运动干预组小鼠骨骼肌细胞内的锰超氧化物歧化酶、p53蛋白表达显著高于红景天对照组(P < 0.05);④与空白对照组相比,单纯运动组小鼠骨骼肌内PGC-1α、LC3-Ⅱ/LC3-Ⅰ水平明显升高,Atg7、P62水平显著下降(均P < 0.05),与红景天对照组相比,红景天运动干预组PGC-1α、LC3-Ⅱ/LC3-Ⅰ水平明显升高,Atg7、P62水平显著下降(均P < 0.05);⑤与空白对照组相比,单纯运动组的融合基因表达下降,分裂基因Drp-1 mRNA表达上升(P < 0.05);红景天运动干预组的融合基因表达也呈下降趋势,Drp-1 mRNA表达水平呈上升趋势,但差异无显著性意义(P > 0.05);⑥结果说明,红景天可显著提高大强度运动量小鼠的运动耐力,这可能与改善了骨骼肌线粒体自噬、起源及线粒体融合-分裂有关。 ORCID: 0000-0002-4143-1195(曹海信) 中国组织工程研究杂志出版内容重点：干细胞;骨髓干细胞;造血干细胞;脂肪干细胞;肿瘤干细胞;胚胎干细胞;脐带脐血干细胞;干细胞诱导;干细胞分化;组织工程     

再灌注损伤心肌线粒体钙代谢与呼吸功能关系的研究

观察离体缺氧-再灌注兔心肌线粒体钙含量、钙摄取率和不同底物的呼吸耗氧量的变化。结果表明:缺氧组心肌线粒体钙含量轻度增加(3.37±0.25nmol/mg pr,P<0.05),钙摄取率无显著变化,以琥珀酸为底物的呼吸耗氧量代偿性增高(226.0±28.7natoms/min/mg Pr,P<0.05),以谷氨酸加苹果酸为底物时变化不显著;再灌注组心肌线粒体钙含量显著增高(6.10±1.12nmol/mgt pr,P<0.01);钙摄取率和以谷氨酸加苹果酸为底物的呼吸耗氧量显著降低(P<0.01),且与线粒体钙含量呈显著负相关(r=-0.73,P<0.001),提示线粒体钙超载在再灌注损伤线粒体功能损害中起重要作用。     

β-淀粉样肽对线粒体的损伤及其在阿尔茨海默病中的作用

阿尔茨海默病(Alzheimer′s disease,AD)是以老年斑(senile plaque,SP)和神经纤维缠结(neurofibrillary tangles,NFTs)为主要病理特征的中枢神经系统退行性疾病,其病因及发病机制至今仍不明确.AD的病变产物β-淀粉样肽(amyloid-βpeptide,Aβ)在线粒体内沉积导致线粒体功能障碍,如ATP产生减少、氧化应激增强、细胞凋亡增强以及线粒体分裂/融合异常等,进而引起AD的一系列病理变化.     

M2型巨噬细胞通过Ac2-26极化调节对急性心力衰竭大鼠血流动力学与心肌线粒体损害的影响研究

为探究膜联蛋白A1(Annexin A1, ANXA1)拟肽Ac2-26对急性心力衰竭(acute heart failure, AHF)模型大鼠的血流动力学与心肌线粒体损伤的影响及作用机制,将研究对象分为对照组、模型组和Ac2-26组(每组15只大鼠),模型组和Ac2-26组大鼠构建AHF模型,且Ac2-26组静脉输注Ac2-26,对照组和模型组静脉输注等体积生理盐水,1次/d,连续14 d。彩色多普勒超声仪检测各组大鼠的血流动力学指标变化;H-E染色观察各组大鼠的心肌组织病理学损伤情况;TUNEL染色观察各组大鼠心肌细胞的凋亡情况;透射电子显微镜观察各组大鼠的心肌线粒体结构;线粒体分离试剂盒分离各组大鼠心肌组织线粒体,JC-1染色观察线粒体膜电位变化;免疫组织化学染色观察各组大鼠心肌组织巨噬细胞标志物CD68、 M1型巨噬细胞标志物iNOS与M2型巨噬细胞标志物CD206的表达;实时荧光定量PCR检测各组大鼠心肌组织中TNF-α、IL-6、TGF-β、IL-10及重组人精氨酸酶1(Arginase 1,Arg-1)的mRNA相对表达量;Western blotting检测各组大鼠心...     

Homozygous mutations in C1QBP as cause of progressive external ophthalmoplegia (PEO) and mitochondrial myopathy with multiple mtDNA deletions

Biallelic mutations in the C1QBP gene have been associated with mitochondrial cardiomyopathy and combined respiratory‐chain deficiencies, with variable onset (including intrauterine or neonatal forms), phenotypes, and severity. We studied two unrelated adult patients from consanguineous families, presenting with progressive external ophthalmoplegia (PEO), mitochondrial myopathy, and without any heart involvement. Muscle biopsies from both patients showed typical mitochondrial alterations and the presence of multiple mitochondrial DNA deletions, whereas biochemical defects of the respiratory chain were present only in one subject. Using next‐generation sequencing approaches, we identified homozygous mutations in C1QBP. Immunoblot analyses in patients' muscle samples revealed a strong reduction in the amount of the C1QBP protein and varied impairment of respiratory chain complexes, correlating with disease severity. Despite the original study indicated C1QBP mutations as causative for mitochondrial cardiomyopathy, our data indicate that mutations in C1QBP have to be considered in subjects with PEO phenotype or primary mitochondrial myopathy and without cardiomyopathy.     

Mutations in TIMM50 cause severe mitochondrial dysfunction by targeting key aspects of mitochondrial physiology

3‐Methylglutaconic aciduria (3‐MGA‐uria) syndromes comprise a heterogeneous group of diseases associated with mitochondrial membrane defects. Whole‐exome sequencing identified compound heterozygous mutations in TIMM50 (c.[341 G>A];[805 G>A]) in a boy with West syndrome, optic atrophy, neutropenia, cardiomyopathy, Leigh syndrome, and persistent 3‐MGA‐uria. A comprehensive analysis of the mitochondrial function was performed in fibroblasts of the patient to elucidate the molecular basis of the disease. TIMM50 protein was severely reduced in the patient fibroblasts, regardless of the normal mRNA levels, suggesting that the mutated residues might be important for TIMM50 protein stability. Severe morphological defects and ultrastructural abnormalities with aberrant mitochondrial cristae organization in muscle and fibroblasts were found. The levels of fully assembled OXPHOS complexes and supercomplexes were strongly reduced in fibroblasts from this patient. High‐resolution respirometry demonstrated a significant reduction of the maximum respiratory capacity. A TIMM50‐deficient HEK293T cell line that we generated using CRISPR/Cas9 mimicked the respiratory defect observed in the patient fibroblasts; notably, this defect was rescued by transfection with a plasmid encoding the TIMM50 wild‐type protein. In summary, we demonstrated that TIMM50 deficiency causes a severe mitochondrial dysfunction by targeting key aspects of mitochondrial physiology, such as the maintenance of proper mitochondrial morphology, OXPHOS assembly, and mitochondrial respiratory capacity.     

A distinct mitochondrial myopathy,lactic acidosis and sideroblastic anemia (MLASA) phenotype associates with YARS2 mutations

Nuclear‐encoded disorders of mitochondrial translation are clinically and genetically heterogeneous. Genetic causes include defects of mitochondrial aminoacyl‐tRNA synthetases, and factors required for initiation, elongation and termination of protein synthesis as well as ribosome recycling. We report on a new case of myopathy, lactic acidosis and sideroblastic anemia (MLASA) syndrome caused by defective mitochondrial tyrosyl aminoacylation. The patient presented at 1 year with anemia initially attributed to iron deficiency. Bone marrow aspirate at 5 years revealed ringed sideroblasts but transfusion dependency did not occur until 11 years. Other clinical features included lactic acidosis, poor weight gain, hypertrophic cardiomyopathy and severe myopathy leading to respiratory failure necessitating ventilatory support. Long‐range PCR excluded mitochondrial DNA rearrangements. Clinical diagnosis of MLASA prompted direct sequence analysis of the YARS2 gene encoding the mitochondrial tyrosyl‐tRNA synthetase, which revealed homozygosity for a known pathogenic mutation, c.156C>G;p.F52L. Comparison with four previously reported cases demonstrated remarkable clinical homogeneity. First line investigation of MLASA should include direct sequence analysis of YARS2 and PUS1 (encoding a tRNA modification factor) rather than muscle biopsy. Early genetic diagnosis is essential for counseling and to facilitate appropriate supportive therapy. Reasons for segregation of specific clinical phenotypes with particular mitochondrial aminoacyl tRNA‐synthetase defects remain unknown. © 2013 Wiley Periodicals, Inc.     

An additional mitochondrial tRNAIle point mutation (A-to-G at nucleotide 4295) causing hypertrophic cardiomyopathy

A third point mutation in the mitochondrial tRNA^Ile gene associated with hypertrophic cardiomyopathy and respiratory chain dysfunction in heart is reported. An A-to-G transition at nucleotide position 4295 was shown to be highly evolutionarily conserved, never present in control individuals, and to segregate with the disease. A PCR-based diagnostic test and endomyocardial biopsies were used to detect both the biochemical deficiency and the level of heteroplasmy in heart. The implications of this new mitochondrial DNA point mutation are discussed. © 1996 Wiley-Liss, Inc.     

A study of 133 Chinese children with mitochondrial respiratory chain complex I deficiency

To investigate the clinical, enzymological and mitochondrial gene profiles of complex I deficiency in Chinese, clinical and laboratory data of the patients (79 boys, 54 girls) were retrospectively assessed. Activities of mitochondrial respiratory chain complexes in peripheral leucocytes were spectrophotometrically measured. The entire mitochondrial DNA (mtDNA) sequence was analyzed in 62 patients. Restriction fragment length polymorphism and gene sequencing analyses were performed in 15 families. Ninety‐one patients had isolated complex I deficiency; 42 had combined deficiencies of complex I and other complexes. The main clinical presentations were neuromuscular disorders (107 patients) and non‐neurological dysfunction (hepatopathy, renal damage and cardiomyopathy; 26 patients). In 32 of 62 patients who underwent mtDNA sequencing, 24 mutations were identified in 15 mitochondrial genes. The 12338T>C, 4833A>G and 14502T>C mutations were found in 12.9%, 11.3% and 4.8% patients, respectively. Seven patients had multiple mutations. Three novel mutations were identified. Chinese patients with complex I deficiency presented heterogeneous phenotypes and genotypes. Twenty‐four mutations were identified in 15 mitochondrial genes in 51.6% patients. mtDNA mutations were more common in isolated complex I deficiency than in combined complex deficiencies. The 12338T>C, 4833A>G and 14502T>C mutations were common.     

Crosstalk between circadian rhythmicity,mitochondrial dynamics and macrophage bactericidal activity

Biological functions show rhythmic fluctuations with 24-hr periodicity regulated by circadian proteins encoded by the so-called ‘clock’ genes. The absence or deregulation of circadian proteins in mice leads to metabolic disorders and in vitro models have shown that the synthesis of pro-inflammatory cytokines by macrophages follows a circadian rhythm so showing a link between circadian rhythmicity, metabolism and immunity. Recent evidence reveals that mitochondrial shape, position and size, collectively referred to as mitochondrial dynamics, are related to both cell metabolism and immune function. However, studies addressing the simultaneous crosstalk between circadian rhythm, mitochondrial dynamics and cell immune function are scarce. Here, by using an in vitro model of synchronized murine peritoneal macrophages, we present evidence that the mitochondrial dynamics and the mitochondrial membrane potential (Δψ_m) follow a circadian rhythmic pattern. In addition, it is shown that the fusion of mitochondria along with high Δψ_m, indicative of high mitochondrial activity, precede the highest phagocytic and bactericidal activity of macrophages on Salmonella typhimurium. Taken together, our results suggest a timely coordination between circadian rhythmicity, mitochondrial dynamics, and the bactericidal capacity of macrophages.     

Complex II deficiency—A case report and review of the literature

Complex II deficiency is a rare cause of mitochondrial respiratory chain defects with a prevalence of 2–23%. It is exclusively nuclear encoded and functions in the citric acid cycle by oxidizing succinate to fumarate and in the mitochondrial electron transport chain (ETC) by transferring electrons to ubiquinone. Of the four subunits, SDHA and SDHB are catalytic and SDHC and SDHD are anchoring. Mutations in SDHA and SDHAF1 (assembly factor) have been found in patients with CII deficiency and a mitochondrial phenotype. We present a patient with CII deficiency with a previously undescribed phenotype of dilated cardiomyopathy, left ventricular noncompaction, failure to thrive, hypotonia, and developmental delay. Also, a comprehensive review of 36 cases published in the literature was undertaken. The results show that CII deficiency has a variable phenotype with no correlation with residual complex activity in muscle although the phenotype and enzyme activities are comparable within a family. For some, the condition was fatal in infancy, others had multisystem involvement and some had onset in adulthood with mild symptoms and normal cognition. Neurological involvement is most commonly observed and brain imaging commonly shows leukoencephalopathy, Leigh syndrome, or cerebellar atrophy. Mutations in SDHAF1 are associated with leukoencephalopathy. Other organ systems like heart, muscle, and eyes are only involved in about 50% of the cases but cardiomyopathy is associated with high mortality and morbidity. In some patients, riboflavin has provided clinical improvement. © 2013 Wiley Periodicals, Inc.     

Wisconsin Stillbirth Service Program

A 40-year-old woman presented with pro found muscle weakness resulting in failure to wean from a ventilator and persistent lactic acidosis after having recovered from a pneumonia complicated by adult respiratory distress syndrome, myocardial infarction, renal failure and shock. She had a 28 year history of chronic anemia and exercise intolerance. Anemia and thrombocytopenia persisted after admission. Nonobstructive hypertrophic cardiomyopathy was present. A stroke-like episode occurred. A mitochondrial myopathy with deficiencies in complexes IV and II was demonstrated, but no DNA defect has yet been found. This patient represents a distinct clinical presentation of a mitochondrial disorder characterized by late onset mitochondrial myopathy, chronic anemia, cardiomyopathy, and lactic acidosis. © 1994 Wiley-Liss, Inc.     

Aspects of paediatric cardiovascular pathology

Examination of the malformed heart requires sequential segmental analysis in which the three paired segments of the heart (atria, ventricles, great arteries) are recognized by their most constant feature. Their connections to each other are established with certainty and associated abnormalities are described. The basic anatomy of the commonest congenital heart defect - ventricular septal defect is described in detail. A knowledge of the normal anatomy of the interventricular septum makes understanding the variation in the morphology of ventricular septal defect easier to understand. The paediatric aspects of cardiomyopathy are described with particular emphasis on those conditions that have a particular relevance to childhood: histiocytoid cardiomyopathy, mitogenic cardiomyopathy, mitochondrial cardiomyopathy, ventricular non-compaction and cardiomyopathy associated with muscular dystrophy and Friedreichs ataxia.