有氧运动改善AD模型APP/PS1双转基因小鼠中枢神经元线粒体融合分裂动态平衡

线粒体融合分裂平衡是线粒体动力学的需要。本研究观察12周规律有氧运动对APP/PS1双转基因小鼠中枢神经元线粒体融合分裂动态平衡的影响。本研究采用3月龄雄性APP/PS1小鼠（AD模型）随机分为AD安静组（AS）、AD运动组（AE）,同月龄雄性C57BL/6J小鼠做正常对照组（CS）。AE组进行12周规律跑台运动,5 d/周,60 min/d。前10 min运动速度12 m/min,后50 min运动速度15 m/min,跑台坡度为0°。八臂迷宫实验检测小鼠工作记忆错误频率和参考记忆错误频率;Western印迹检测小鼠皮层、海马组织中线粒体分裂蛋白Drp1和Fis1的含量,以及Drp1的活性（p-Drp1-Ser616）、线粒体融合蛋白Mfn1、Mfn2、Opa1的表达水平;透射电镜观察皮层、海马线粒体形态结构、健康线粒体比率及线粒体平均直径。本研究证实AS组较CS组工作记忆错误频率显著提高（P<0.05）,12周有氧运动显著降低工作记忆错误频率（P<0.05）。AS组小鼠皮层Fis1蛋白和海马脑区Drp1、Fis1蛋白表达水平及皮层、海马脑区Drp1蛋白的活性增加（P<0.05）。而皮层Mfn1和海马Mfn1、Mfn2蛋白表达水平显著降低（P<0.05）。12周有氧运动显著减低Fis1、Drp1蛋白表达及Drp1蛋白的活性,提高Mfn1、Mfn2蛋白表达水平（P<0.05）。AS组小鼠皮层、海马线粒体多呈现球形,部分线粒体膜结构消失,线粒体嵴结构紊乱。且AS组较CS组小鼠健康线粒体比率降低、直径缩短。12周规律有氧运动可明显改善线粒体形态和结构,提高健康线粒体比率及直径。本研究提示,12周规律有氧运动可有效抑制皮层、海马脑区线粒体分裂蛋白Drp1和 Fis1的表达,降低Drp1的活性（p-Drp1-Ser616）,上调线粒体融合蛋白Mfn1、Mfn2的蛋白表达水平,改善线粒体形态和结构以促进线粒体质量控制,是有氧运动改善AD模型空间学习记忆能力的分子机制之一。     

线粒体融合与分裂在中枢神经系统疾病中的研究进展

线粒体是一种高度动态的细胞器,通过不断的融合和分裂维持其动态平衡,参与生理病理功能调节。线粒体融合与分裂主要由融合分裂相关蛋白调控,如Drp1、Fis1、Mfn1、Mfn2、OPA1等,多种诱导因子通过调节线粒体融合分裂相关蛋白表达及活化进而调节线粒体形态和生理功能。现有研究表明线粒体融合分裂的异常可能是许多中枢神经系统疾病的发病机制之一。本文从线粒体融合分裂的分子调控机制及其在缺血性脑中风、帕金森综合征和阿尔兹海默症等中枢神经系统疾病中的研究进展方面进行综述,为相关疾病的防治提供一定参考和线索。     

哺乳动物细胞线粒体融合-分裂与钙离子信号的关系

线粒体是一种高度动态的细胞器,通过融合和分裂两个相反的过程来维持正常的形态结构。在哺乳动物中,多种因素影响线粒体的融合-分裂的平衡,但现已明确,线粒体融合的主要调节因子为Mfn1/2、OPA1,介导线粒体分裂的主要调节因子为Drp1、Fis1。新近研究发现,线粒体融合-分裂平衡的紊乱将导致线粒体结构和在细胞内分布的异常,进而影响细胞和线粒体对钙离子信号的反应;同时,钙离子也可通过多种机制影响线粒体的形态结构与分布。     

促线粒体融合蛋白在线粒体融合和细胞凋亡中的作用

一直以来,线粒体动态变化都备受关注,这不仅关系到线粒体本身,也与细胞的整体状态密切相关。线粒体动态变化主要指线粒体的分裂和融合,该过程涉及一系列蛋白质。在线粒体融合中,目前研究得较深入的促线粒体融合蛋白主要有Mfn1、Mfn2和OPA1。随着研究的深入,发现这3种蛋白质不仅对于线粒体融合有重要作用,在细胞凋亡过程中也扮演着重要角色。现就Mfn1、Mfn2和OPA1的促线粒体融合作用及其与细胞凋亡的关系作详细阐述。     

泛素特异性蛋白酶30在线粒体动力学和自噬中的作用研究进展

线粒体作为细胞的能量中心,在细胞内呈现高度的动态变化,其数量、质量及功能的稳定对维持细胞的正常活动至关重要。线粒体动力学与线粒体自噬之间可互相调控,共同构成线粒体质量控制的重要环节。泛素特异性蛋白酶30 (USP30)作为去泛素化酶,既可通过线粒体融合蛋白1/2 (Mfn1/2)、线粒体动力蛋白相关蛋白1 (Drp1)等融合与分裂蛋白参与调控线粒体动力学过程,还能通过E3泛素连接酶Parkin、泛素(Ub)及电压依赖性阴离子通道1 (VDAC1)等多种信号而调控PTEN诱导激酶1 (PINK1)/Parkin途径介导的线粒体自噬,但其详细机制尚未完全阐明。本文对USP30在调控线粒体动力学和线粒体自噬中的作用与其机制进行了综述。     

小鼠肝再生过程中ROS及线粒体代谢变化规律的研究

目的:肝脏是维持人体发挥功能的重要器官,同时肝脏再生能力十分强大。本文通过部分肝切除术后小鼠肝再生模型,观察肝再生过程中氧化应激及线粒体代谢变化规律,以期为将来的调控肝再生提供新的干预靶点。方法:选择雄性健康体重均匀的Balb/c小鼠,采用经典70%肝切除模型,随机分为假手术对照组(Sham组)以及70%肝切除组(70%PH组)。肝切除术后6 h、1d、2 d、3 d、5 d、7 d不同时间点取肝组织,制备冰冻切片检测活性氧(ROS)水平,Western blot分别检测细胞增殖相关蛋白PCNA、Cyclin D1;氧化应激相关蛋白SOD1、SOD2、CAT、GPX1;以及线粒体代谢相关蛋白PGC-1α、Nrf1、TFAM、Drp1、Fis1、Mfn1、Mfn2、OPA1的表达并分析其变化规律。结果:70%肝切除术后小鼠肝脏增长迅速,细胞增殖关键蛋白PCNA和Cyclin D1表达显著增加;在此过程中细胞ROS水平呈现先升高后降低的变化,细胞主要抗氧化酶SOD1、SOD2、CAT、Gpx1与ROS相一致出现先升高后降低的变化。线粒体生物合成调控因子PGC-1α、Nrf1、TFAM呈现先降低后升高的趋势,而线粒体分裂蛋白Drp1和Fis1呈现先降低后显著升高的趋势,线粒体融合相关蛋白Mfn1、Mfn2和OPA1总体为先降低后恢复至正常水平。结论:在小鼠70%肝切除再生过程中,存在着明显的氧化应激,线粒体生物合成增加,线粒体分裂/融合平衡偏向分裂,并且这些变化呈现具有一定的时间变化规律,这些变化及规律很可能作为将来调控肝再生的重要的潜在干预靶点。     

CLIC1通过干扰线粒体动力学平衡促进内皮细胞损伤的研究

该文通过研究H2O2诱导人脐静脉内皮细胞(HUVEC)中氯离子通道蛋白1(chloride intracellular channel 1, CLIC1)对线粒体动力学平衡的影响,探讨CLIC1在内皮细胞损伤中的作用及机制。体外培养HUVEC细胞,分别用CLIC1抑制剂IAA94(40μmol/L)、H2O2(0.9 mmol/L)、IAA94(40μmol/L)和H2O2(0.9 mmol/L)联合处理,荧光法检测细胞活性氧(reactive oxygen species,ROS)和丙二醛(malondialdehyde, MDA)的含量; JC-1染色法检测细胞线粒体膜电位的变化;定量PCR技术检测CLIC1、线粒体动力相关蛋白1(dynamin-related protein 1, Drp1)以及线粒体融合蛋白1(mitofusin 1, Mfn1)的mRNA表达;免疫印迹技术检测CLIC1、Drp1蛋白的水平。结果显示:与正常组相比, H2O2处理的内皮细胞中ROS、MDA含量增加(P0.05), CLIC1表达量上调(P0.05),三磷酸腺苷(ATP)含量减少(P0.05),线粒体膜电位降低(P0.001),线粒体融合蛋白Mfn1表达显著降低(P0.05),线粒体分裂蛋白Drp1表达显著升高(P0.05);而IAA94预处理2 h后,内皮细胞中ROS、MDA含量减少(P0.05),线粒体融合蛋白Mfn1表达显著增加(P0.05),线粒体分裂蛋白Drp1表达显著降低(P0.05),线粒体膜电位升高(P0.001)。以上结果表明, CLIC1在H2O2诱导的内皮细胞线粒体损伤中发挥重要作用,其机制可能与CLIC1干扰线粒体动力学平衡有关。     

线粒体分裂、融合与细胞凋亡

线粒体是高度动态变化的细胞器,其在细胞内不断分裂、融合并形成网状结构。线粒体的分裂和融合是由多种蛋白质精确调控完成的。Drp1／Dnm1p,Fis1／Fis1p,Caf4p和Mdv1p参与线粒体分裂的调控;Mfn1／2／Fzo1p控制线粒体外膜的融合,而Mgm1p／OPA1则参与线粒体内膜的融合。在细胞凋亡过程中线粒体片段化,网状结构被破坏,线粒体嵴发生重构,抑制这一过程可以部分抑制细胞色素c的释放和细胞凋亡。线粒体形态对于细胞维持正常生理代谢和机体发育起着重要的作用,一旦出现障碍会导致严重的疾病。     

线粒体动力学在糖尿病心肌病中的作用及调节机制

心血管并发症是糖尿病患者死亡的首要原因。其中,糖尿病心肌病是排除了高血压、冠心病所致的心肌损伤后的一类特异性心肌病,其特征在于心肌细胞的代谢异常和心脏功能的逐渐衰退,临床表现为早期心肌舒张功能受损,晚期心肌收缩功能受损,最终发展为心力衰竭。线粒体是心肌细胞内提供能量的主要细胞器,线粒体动力学是指线粒体进行融合和分裂的动态过程,是线粒体质量控制的重要途径,线粒体动力学在维持线粒体稳态与心脏功能中起着至关重要的作用。调节线粒体分裂的蛋白主要是Drp1及其受体Fis1、MFF、MiD49和MiD51,执行线粒体外膜融合的蛋白为Mfn1/2,内膜融合蛋白为Opa1。本文综述了近期在糖尿病心肌病线粒体动力学方面的系列研究成果：1型与2型糖尿病心肌病的线粒体动力学失衡均表现为分裂增加与融合受阻,前者的分子机制主要是Drp1上调与Opa1下调,后者的分子机制主要为Drp1上调与Mfn1/2下调,线粒体分裂增加和融合受阻可导致线粒体功能障碍,促进糖尿病心肌病的发生、发展。中药单体安石榴苷、丹皮酚和内源性物质褪黑素等活性成分可通过抑制线粒体分裂或促进线粒体融合,改善线粒体功能,减轻糖尿病心肌病症状。本文...     

线粒体动力学改变在神经变性疾病中的地位

线粒体是一种处于高度运动状态的细胞器,频繁地出现分裂和融合,线粒体分裂和融合的动态过程被称为线粒体动力学。对于神经元来说,线粒体的动力学过程具有十分重要的生物学意义。已知线粒体融合介导蛋白的功能缺失性突变可以导致常染色体显性遗传性视神经萎缩和Charcot-Marie-Tooth病等神经变性疾病。近来发现,在迟发性神经变性疾病中,线粒体动力学的改变也具有重要地位。本文将在线粒体动力学的分子调控以及与细胞死亡的关系、在神经变性疾病中的地位等方面综述这一领域的最新进展。     

Mitochondrial remodeling following fission inhibition by 15d-PGJ2 involves molecular changes in mitochondrial fusion protein OPA1

We showed earlier that 15 deoxy Δ^12,14 prostaglandin J2 (15d-PGJ2) inactivates Drp1 and induces mitochondrial fusion [1]. However, prolonged incubation of cells with 15d-PGJ2 resulted in remodeling of fused mitochondria into large swollen mitochondria with irregular cristae structure. While initial fusion of mitochondria by 15d-PGJ2 required the presence of both outer (Mfn1 and Mfn2) and inner (OPA1) mitochondrial membrane fusion proteins, later mitochondrial changes involved increased degradation of the fusion protein OPA1 and ubiquitination of newly synthesized OPA1 along with decreased expression of Mfn1 and Mfn2, which likely contributed to the loss of tubular rigidity, disorganization of cristae, and formation of large swollen degenerated dysfunctional mitochondria. Similar to inhibition of Drp1 by 15d-PGJ2, decreased expression of fission protein Drp1 by siRNA also resulted in the loss of fusion proteins. Prevention of 15d-PGJ2 induced mitochondrial elongation by thiol antioxidants prevented not only loss of OPA1 isoforms but also its ubiquitination. These findings provide novel insights into unforeseen complexity of molecular events that modulate mitochondrial plasticity.     

Structure,function, and regulation of mitofusin‐2 in health and disease

Mitochondria are highly dynamic organelles that constantly migrate, fuse, and divide to regulate their shape, size, number, and bioenergetic function. Mitofusins (Mfn1/2), optic atrophy 1 (OPA1), and dynamin‐related protein 1 (Drp1), are key regulators of mitochondrial fusion and fission. Mutations in these molecules are associated with severe neurodegenerative and non‐neurological diseases pointing to the importance of functional mitochondrial dynamics in normal cell physiology. In recent years, significant progress has been made in our understanding of mitochondrial dynamics, which has raised interest in defining the physiological roles of key regulators of fusion and fission and led to the identification of additional functions of Mfn2 in mitochondrial metabolism, cell signalling, and apoptosis. In this review, we summarize the current knowledge of the structural and functional properties of Mfn2 as well as its regulation in different tissues, and also discuss the consequences of aberrant Mfn2 expression.     

Loss of Drp1 function alters OPA1 processing and changes mitochondrial membrane organization

RNAi mediated loss of Drp1 function changes mitochondrial morphology in cultured HeLa and HUVEC cells by shifting the balance of mitochondrial fission and fusion towards unopposed fusion. Over time, inhibition of Drp1 expression results in the formation of a highly branched mitochondrial network along with “bulge”-like structures. These changes in mitochondrial morphology are accompanied by a reduction in levels of Mitofusin 1 (Mfn1) and 2 (Mfn2) and a modified proteolytic processing of OPA1 isoforms, resulting in the inhibition of cell proliferation. In addition, our data imply that bulge formation is driven by Mfn1 action along with particular proteolytic short-OPA1 (s-OPA1) variants: Loss of Mfn2 in the absence of Drp1 results in an increase of Mfn1 levels along with processed s-OPA1-isoforms, thereby enhancing continuous “fusion” and bulge formation. Moreover, bulge formation might reflect s-OPA1 mitochondrial membrane remodeling activity, resulting in the compartmentalization of cytochrome c deposits. The proteins Yme1L and PHB2 appeared not associated with the observed enhanced OPA1 proteolysis upon RNAi of Drp1, suggesting the existence of other OPA1 processing controlling proteins. Taken together, Drp1 appears to affect the activity of the mitochondrial fusion machinery by unbalancing the protein levels of mitofusins and OPA1.     

Molecular mechanism of mitochondrial membrane fusion

Mitochondrial fusion requires coordinated fusion of the outer and inner membranes. This process leads to exchange of contents, controls the shape of mitochondria, and is important for mitochondrial function. Two types of mitochondrial GTPases are essential for mitochondrial fusion. On the outer membrane, the fuzzy onions/mitofusin proteins form complexes in trans that mediate homotypic physical interactions between adjacent mitochondria and are likely directly involved in outer membrane fusion. Associated with the inner membrane, the OPA1 dynamin-family GTPase maintains membrane structure and is a good candidate for mediating inner membrane fusion. In yeast, Ugo1p binds to both of these GTPases to form a fusion complex, although a related protein has yet to be found in mammals. An understanding of the molecular mechanism of fusion may have implications for Charcot-Marie-Tooth subtype 2A and autosomal dominant optic atrophy, neurodegenerative diseases caused by mutations in Mfn2 and OPA1.     

Control of mitochondrial morphology through differential interactions of mitochondrial fusion and fission proteins

Mitochondria in mammals are organized into tubular networks that undergo frequent shape change. Mitochondrial fission and fusion are the main components mediating the mitochondrial shape change. Perturbation of the fission/fusion balance is associated with many disease conditions. However, underlying mechanisms of the fission/fusion balance are not well understood. Mitochondrial fission in mammals requires the dynamin-like protein DLP1/Drp1 that is recruited to the mitochondrial surface, possibly through the membrane-anchored protein Fis1 or Mff. Additional dynamin-related GTPases, mitofusin (Mfn) and OPA1, are associated with the outer and inner mitochondrial membranes, respectively, and mediate fusion of the respective membranes. In this study, we found that two heptad-repeat regions (HR1 and HR2) of Mfn2 interact with each other, and that Mfn2 also interacts with the fission protein DLP1. The association of the two heptad-repeats of Mfn2 is fusion inhibitory whereas a positive role of the Mfn2/DLP1 interaction in mitochondrial fusion is suggested. Our results imply that the differential binding of Mfn2-HR1 to HR2 and DLP1 regulates mitochondrial fusion and that DLP1 may act as a regulatory factor for efficient execution of both fusion and fission of mitochondria.     

Death-associated Protein 3 Regulates Mitochondrial-encoded Protein Synthesis and Mitochondrial Dynamics

Mitochondrial morphologies change over time and are tightly regulated by dynamic machinery proteins such as dynamin-related protein 1 (Drp1), mitofusion 1/2, and optic atrophy 1 (OPA1). However, the detailed mechanisms of how these molecules cooperate to mediate fission and fusion remain elusive. DAP3 is a mitochondrial ribosomal protein that involves in apoptosis, but its biological function has not been well characterized. Here, we demonstrate that DAP3 specifically localizes in the mitochondrial matrix. Knockdown of DAP3 in mitochondria leads to defects in mitochondrial-encoded protein synthesis and abnormal mitochondrial dynamics. Moreover, depletion of DAP3 dramatically decreases the phosphorylation of Drp1 at Ser-637 on mitochondria, enhancing the retention time of Drp1 puncta on mitochondria during the fission process. Furthermore, autophagy is inhibited in the DAP3-depleted cells, which sensitizes cells to different types of death stimuli. Together, our results suggest that DAP3 plays important roles in mitochondrial function and dynamics, providing new insights into the mechanism of a mitochondrial ribosomal protein function in cell death.