Valsartan Inhibits Angiotensin Ⅱ-induced Proliferation of Vascular Smooth Muscle Cells via Regulating the Expression of Mitofusin 2

Angiotensin Ⅱ (ANGⅡ) plays an important role in the pathogenesis of atherosclerosis by inducing proliferation of vascular smooth muscle cells (VSMCs).In our study,we observed the effects of valsartan on proliferation of cultured VSMCs treated with or without ANGⅡ by cell counting and methyl thiazolyl tetrazolium (MTT) assay,and detected the expression of mitofusin 2 (Mfn2),a newly discovered cell proliferation inhibitor and a related cell proliferation signaling pathway pro-tein by Western blotting.ANGⅡ at a concentration of 10-6 mol/L significantly stimulated VSMCs proliferation,down-regulated the expression of Mfn2 and upregulated the expression of Raf and ERK1/2.Valsartan inhibited such effects of ANGⅡ at concentrations of 10-5 and 10-6 mol/L,but not at 10-7 mol/L.Valsartan had no significant effect on the proliferation of untreated VSMCs.These results suggest that valsartan inhibits ANGⅡ-induced proliferation of VSMCs in vitro via Mfn2-Ras-Raf-ERK/MAPK signaling pathway.

Chang’an decoction(肠安方)alleviates endoplasmic reticulum stress by regulating mitofusin 2 to improve colitis

OBJECTIVE:To evaluate the protective effects of Chang'an decoction(肠安方,CAD)on colitis,and investigate the potential mechanisms underlying these effects from the perspectives of endoplasmic reticulum(ER)stress induced by mitofusin 2(MFN2).METHODS:The composition of CAD was identified by liquid chromatography-mass spectrometry technology.A mice model of dextran sulfate sodium(DSS)induced colitis was established and therapeutic effects of CAD were determined by detecting body weight,disease activity index,colon length and histopathological changes.Then,the expression levels of MFN2,ER stress markers and Nucleotide-binding domain and leucine-rich repeat protein3(NLRP3)relevant proteins were detected by polymerase chain reaction(PCR),Western blot,immunohistochemistry and immunofluorescence staining.Subsequently,knockdown and overexpression cell model were constructed to further investigate the underlying mechanism of MFN2 mediating ER stress and energy metabolism by PCR,Western blot,electron microscopy and reactive oxygen species(ROS)staining.Finally,inflammatory indicator and tight junction proteins were measured by PCR and immunofluorescence staining to evaluate the protective effects of CAD.RESULTS:Results showed that the indispensable regulatory role of MFN2 in mediating ER stress and mitochondrial damage was involved in the protective effects of CAD on colitis in mice fed with DSS.Network pharmacology analysis also revealed CAD may play a protective effect on colitis by affecting mitochondrial function.In addition,our data also suggested a causative role for MFN2 in the development of inflammatory responses and energy metabolic alterations by constructing a knockdown and overexpression cell model whereby alter proper ER-mitochondria interaction in Caco-2 cells.Furthermore,relative expression analyses of ER stress markers and NLRP3 inflammasome showed the onset of ER stress and activation of NLRP3 inflammasome,which is consistent with the above findings.In contrast,intervention of CAD could improve the mucosal barrier integrity and colonic inflammatory response effectively through inhibiting ER stress response mediated by MFN2.CONCLUSION:CAD could alleviate ER stress by regulating MFN2 to exert therapeutic effects on DSS-induced colitis,which might provide an effective natural therapeutic approach for the treatment of ulcerative colitis.

线粒体融合蛋白Mfn2在阿尔茨海默病中的研究进展

线粒体融合蛋白2(Mfn2)作为调节线粒体融合的关键因子,通过调控线粒体的融合裂变过程来维持线粒体数量、结构和生物功能等动态变化,线粒体动力学的稳态是调节细胞器功能的前提,线粒体功能障碍是包括阿尔茨海默病(AD)在内的神经退行性疾病的特征之一。在AD患者的大脑中,β-淀粉样蛋白(Aβ)聚集和Tau蛋白过度磷酸化的同时,Mfn2的表达水平明显下降,因此,Mfn2在AD的发病过程中可能发挥重要的作用。本文主要综述了Mfn2在AD线粒体动力学中的作用。了解Mfn2与AD发病机制的相关性,将为开发与线粒体功能障碍相关疾病的治疗提供重要信息。

线粒体融合蛋白2在缺血再灌注损伤中作用的研究进展

线粒体融合蛋白2(Mfn2)介导线粒体融合与分裂过程,参与调控线粒体动力学,是线粒体形态、结构和功能的动力素相关蛋白。缺血再灌注损伤(IRI)是外科手术中一种常见的并发症,也是创伤性休克、严重感染等致命疾病的主要死亡原因。近年来发现,Mfn2在IRI中具有修复作用,包括肠IRI、肺IRI、肾IRI和心脏IRI等。Mfn2通过多个途径参与不同IRI的修复,减缓疾病进展。深入研究Mfn2与IRI的关系及相关机制,可为IRI的防治提供新的靶点和思路。

Mitofusin-2在大鼠蛛网膜下腔出血后大脑动脉内表达的变化（英文）

目的研究Mitofusin-2(Mfn2)在大鼠蛛网膜下腔出血(SAH)后大脑动脉中表达的变化,寻找Mfn2基因与脑血管痉挛(CVS)之间的关系。方法蛛网膜下腔出血模型由刺破颈内动脉的颅内动脉分叉处诱导。146只SD大鼠被随机分为6组:假手术组(sham组),SAH后24h、48h、72h、7d和14d各组。计算动物死亡率,测定神经功能学评分及脑水含量。组织学检测观察形态学变化,采用Western blotting及RT-PCR分别检测SAH后不同时间点的大鼠主要大脑动脉Mfn2蛋白及mRNA水平的表达变化。结果围绕在基底动脉周围的血块随着时间逐渐消失,形态学观察显示SAH 24h组基底动脉出现严重的痉挛。SAH7d组的基底动脉中层无阳性的免疫组织化学阳性染色。Western blotting结果显示,Mfn2蛋白表达sham组与SAH48h组和SAH72h组相比,均显著增加(P<0.05),SAH 7d出现显著性降低(P<0.05),SAH14d恢复至sham和SAH24h组水平。而mRNA水平变化与蛋白水平变化相类似。Mfn2基因参与到SAH后血管的自我调节过程中,表达随着时间增加而增加,并在72h到达高峰,7d时显著下降,14d左右恢复至sham组水平。结论Mfn2在SAH后的早期以及迟发型脑血管痉挛中起重要作用,为揭示SAH后脑血管痉挛的机理提供实验依据。

Correlations between Mitofusin 2 Expression in Fibroblasts and Pelvic Organ Prolapse： An In vitro Study

Background：Both Mitofusin 2 （Mfn2） and pelvic organ prolapse （POP） are related to aging.The aim of the present study was to investigate the variations of Mfn2 expression in the uterosacral ligaments of patients with and/or without POP and their correlations with the expression of procollagen.Methods：Fibroblasts were cultured using tissue specimens that were harvested from the uterosacral ligaments of POP and non-POP （NPOP） patients （n =10 for each group） from September 2016 to December 2016.The Cell Counting Kit-8 （CCK-8） assay was used to compare the differences in cell proliferation between the two groups.Relative quantitative reverse transcription-polymerase chain reaction and Western blotting assays were employed to assess the differences in the mRNA and protein expression levels of Mfn2 and procollagen 1A1/1A2/3A1 between the two groups.The changes in procollagen expression were assessed following the downregulation of Mfn2 in the POP group using RNAi.The data were assessed with independent sample t-test or general linear model univariate analysis using the SPSS 13.0 software.Results：The results from CCK-8 assay indicated that cell viability in the POP group was significantly lower compared with that of the NPOP group （td5,7,9,11=-5.925,-6.851,-9.129,and-9.661,respectively,all P 〈 0.001,from D5 to D 11）.The mRNA and protein expression levels of Mfn2 in the cultured fibroblasts of the POP group were significantly higher compared with those of the NPOP group （mRNA：t =2.425,P =0.032;protein：t =2.392,P =0.037,respectively）,whereas only the expression levels of procollagen 1A1/1A2/3A1 were significantly higher in the NPOP group （mRNA：t =-2.165,P1A1 =0.041;t =-2.741,P1A2 =0.026;t =-2.147,P3A1 =0.045,respectively;protein：t =-2.418,P1A1 =0.029;t =-2.405,P1A2 =0.033;t =-2.470,P3A1 =0.012,respectively）.The expression levels of procollagen in the POP group increased following the downregulation of Mfn2.Conclusions：The proliferation rate and cell viability of the fibroblasts in the POP group were significantly lower compared with those in the NPOP group.In the POP fibroblasts,Mfn2 expression was increased,while procollagen expression was decreased.

Mitofusin2 Decreases Intracellular Cholesterol of Oxidized LDL-Induced Foam Cells from Rat Vascular Smooth Muscle Cells

Mitofusin2 （Mfn2） plays a pivotal role in the proliferation and apoptosis of vascular smooth muscle cells （VSMCs）. The purpose of this study was to investigate the effects of Mfn2 on the traffick- ing of intracellular cholesterol in the foam ceils derived from rat VSMCs （rVSMCs） and also to investigate the effects of Mfn2 on the expression of adenosine triphosphate-binding cassette subfamily A member 1 （ABCA1）, adenosine triphosphate-binding cassette subfamily G member 1 （ABCG1） and peroxisome proliferator-activated receptor gamma （PPARy）. The rVSMCs were co-cultured with oxi- dized low density lipoprotein （LDL, 80 ~tg/mL） to produce foam cells and cholesterol accumulation in cells. Before oxidized LDL treatment, different titers （20, 40 and 60 pfu/cell） of recombinant adenovirus containing Mfn2 gene （Adv-Mfn2） were added into the culture medium for 24 h to transfect the Mfn2 gene into the rVSMCs. Then the cells were harvested for analyses. The protein expression of Mfn2 was significantly higher in Adv-Mfn2-transfected group than in untransfected group （P〈0.05）, and the ex- pression levels significantly increased when the titer of Adv-Mfn2 increased （P〈0.05）. At 24 or 48 h af- ter oxidized LDL treatment, rVSMCs became irregular and their nuclei became larger, and their plasma abounded with red lipid droplets. However, the number of red lipid droplets was significantly decreased in Adv-Mfn2-transfected group as compared with untransfected group. At 48 h after oxidized LDL treatment, the intracellular cholesterol in rVSMCs was significantly increased （P〈0.05）, but it was sig- nificantly decreased in Adv-Mfn2-transfected group as compared with untransfected group （P〈0.05）, and it also significantly decreased when the titer of Adv-Mfn2 increased （P〈0.05）. The mRNA and pro- tein expression levels of ABCA1 and ABCG1 were significantly increased in Adv-Mfn2-transfected group as compared with untransfected group （P〈0.05）. Though the mRNA and protein expression levels of PPARy was not significantly increased （P〉0.05）, the phosporylation levels of PPARy were signifi- cantly decreased in Adv-Mfn2-transfected group as compared with untransfected group （P〈0.05）. These results suggest that the transfection of Adv-Mfn2 can significantly reduce intracellular cholesterol in oxidized LDL-induced rVSMCs possibly by decreasing PPAR＇/phosporylation and then increasing pro- tein expression levels of ABCAI and ABCG1, which may be helpful to suppress the formation of foam cells.

A novel mitofusin 2 gene mutation causing Charcot-Marie-Tooth type 2A disease in a Chinese family

Charcot-Marie-Tooth disease （CMT）, also known as hereditary motor and sensory neuropathies,comprises a genetically heterogeneous group of inherited peripheral neuropathies. Clinically it is characterized by progressive distal weakness, muscle atrophy, distal sensory loss and loss of deep tendon reflexes. Following electrophysiological criteria, CMT is divided into two main forms：

Mitofusin2参与石棉肺发生机制研究

[目的]以新的切入点探讨石棉引起肺泡上皮细胞凋亡的分子机制.[方法]石棉暴露下,应用免疫荧光染色免疫法和免疫印迹法观察Mitofusin 2(MFN2)的变化;分别用衣霉素(TN)、钙离子阻滞剂和MFN2RNAi处理A549细胞,观察内质网与线粒体空间距离的变化.[结果]石棉可使MFN2表达上调;与正常对照组比较,TN组、钙离子阻滞组和MFN2RNAi组内质网与线粒体间的间隙均明显缩短.[结论]MFN2在石棉肺的发生发展过程中起一定的作用.

Mitofusin-2 ameliorates high-fat diet-induced insulin resistance in liver of rats

AIM:To investigate the effects of mitofusin-2(MFN2) on insulin sensitivity and its potential targets in the liver of rats fed with a high-fat diet(HFD).METHODS:Rats were fed with a control or HFD for 4 or 8 wk,and were then infected with a control or an MFN2 expressing adenovirus once a week for 3wk starting from the 9th wk.Blood glucose(BG),plasma insulin and insulin sensitivity of rats were determined at end of the 4th and 8th wk,and after treatment with different amounts of MFN2 expressing adenovirus(108,109 or 1010 vp/kg body weight).BG levels were measured by Accu-chek Active Meter.Plasma insulin levels were analyzed by using a Rat insulin enzymelinked immunosorbent assay kit.Insulin resistance was evaluated by measuring the glucose infusion rate(GIR) using a hyperinsulinemic euglycemic clamp technique.The expression or phosphorylation levels of MFN2 and essential molecules in the insulin signaling pathway,such as insulin receptor(INSR),insulin receptor substrate 2(IRS2),phosphoinositide-3-kinase(PI3K),protein kinase beta(AKT2) and glucose transporter type 2(GLUT2) was assayed by quantitative real-time polymerase chain reaction and Western-blotting.RESULTS:After the end of 8wk,the body weight of rats receiving the normal control diet(ND) and the HFD was not significantly different(P>0.05).Compared with the ND group,GIR in the HFD group was significantly decreased(P<0.01),while the levels of BG,triglycerides(TG),total cholesterol(TC) and insulin in the HFD group were significantly higher than those in the ND group(P<0.05).Expression of MFN2 mRNA and protein in liver of rats was significantly downregulated in the HFD group(P<0.01) after 8 wk of HFD feeding.The expression of INSR,IRS2 and GLUT2 were down-regulated markedly(P<0.01).Although there were no changes in PI3K-P85 and AKT2 expression,their phosphorylation levels were decreased significantly(P<0.01).After intervention with MFN2 expressing adenovirus for 3wk,the expression of MFN2 mRNA and protein levels were up-regulated(P<0.01).There was no difference in body weight of rats between the groups.The levels of BG,TG,TC and insulin in rats were lower than those in the Ad group(P<0.05),but GIR in rats infected with Ad-MFN2 was significantly increased(P<0.01),compared with the Ad group.The expression of INSR,IRS2 and GLUT2 was increased,while phosphorylation levels of PI3K-P85 and AKT2 were increased(P<0.01),compared with the Ad group.CONCLUSION:HFDs induce insulin resistance,and this can be reversed by MFN2 over-expression targeting the insulin signaling pathway.

Jixuecao(Herba Centellae Asiaticae) alleviates mesangial cell proliferation in IgA nephropathy by inducing mitofusin 2 expression

OBJECTIVE:To investigate the effect of mitofusin 2 (Mfn2) and its downstream signaling pathway on glomerular mesangial cells (GMCs) proliferation in IgA nephropathy (IgAN),as well as the mechanism of action of Jixuecao (Herba Centellae Asiaticae,HCA) in the treatment of IgAN.METHODS:Adenovirus-mediated Mfn2 gene transfection and Mfn2 expression were analyzed by real-time polymerase chain reaction (PCR) and Western blotting.IgA1 induced the proliferation of GMCs,which were then treated with HCA.Cell proliferation was detected with cell counting kit-8 (CCK-8),and Mfn2 expression was analyzed by real-time PCR and western blotting.An IgAN animal model was also established and treated with HCA.GMCs proliferation was detected by hematoxylin-eosin staining,mitochondrial structure was analyzed by electron microscopy,mitochondrial function was determined by the Clark oxygen electrode method,and the expression of Mfn2,Phospho-extracellular regulated protein kinases1/2 (P-ERK1/2),Cyclin-dependent kinase 2 (CDK2),Phospho-p27 (p-p27),and cyclin A was analyzed by Western blotting.RESULTS:In vitro,HCA inhibited GMCs in a concentration-dependent manner in association with the upregulation of Mfn2 expression.The overexpression of Mfn2 inhibited IgA1-induced GMCs proliferation and elevated the effect of HCA.In vivo,treatment with HCA could alleviate albuminuria and creatinine and GMCs proliferation.These effects were related to the upregulation of Mfn2,p-p27 and inhibition of p-ERK1/2,CDK2,and cyclinA.Mitochondrial swelling,vacuolar degeneration,and reduction of respiratory control rate were identified in IgAN,but HCA could improve the mitochondrial structure and function.CONCLUSION:HCA inhibited GMCs proliferation via the upregulation Mfn2 and the inhibition of Ras-Raf-ERK/MAPK.We revealed that changes of mitochondrial structure and function are associated with IgAN,but that HCA can improve these mitochondrial features.

黄芪注射液对血管紧张素Ⅱ诱导的H9c2细胞凋亡的抑制作用和机制研究

目的:探讨黄芪注射液对血管紧张素Ⅱ(AngⅡ)诱导的H9c2心肌细胞凋亡的抑制作用及其可能作用机制。方法:采用细胞计数试剂盒-8(CCK-8)方法筛选H9c2细胞培养的黄芪注射液浓度;H9c2细胞分为正常对照组、AngⅡ模型组、AngⅡ+黄芪注射液组。采用实时定量聚合酶链式反应(RT-PCR)法检测3组H9c2细胞电压依赖性阴离子通道1(VDAC1)、线粒体融合蛋白2(Mfn2)及分子伴侣葡萄糖调节蛋白75(GRP75)mRNA的表达;蛋白免疫印迹法(Western Blot)检测VDAC1、Mfn2、GRP75的蛋白表达;Fura-2 AM法测定细胞内Ca^(2+)浓度变化;用流式细胞仪检测各组细胞凋亡情况。结果:黄芪注射液在浓度为0.125%时对细胞的促增殖作用最为显著。与正常对照组比较,AngⅡ模型组Mfn2、GRP75 mRNA表达水平明显增加(P<0.05),AngⅡ+黄芪注射液组Mfn2、GRP75 mRNA表达低于AngⅡ模型组(P<0.05或P<0.01),而3组VDAC1 mRNA表达比较差异无统计学意义(P>0.05)。与正常对照组比较,AngⅡ模型组VDAC1、Mfn2和GRP75的蛋白表达明显增加(P<0.05或P<0.01),AngⅡ+黄芪注射液组VDAC1、Mfn2、GRP75的蛋白表达低于AngⅡ模型组(P<0.01)。与正常对照组比较,AngⅡ模型组细胞钙含量、细胞凋亡率明显增加(P<0.05或P<0.01),AngⅡ+黄芪注射液组细胞钙含量、细胞凋亡率低于AngⅡ模型组(P<0.01)。结论:黄芪注射液能够抑制血管紧张素Ⅱ诱导的H9c2心肌细胞凋亡,其机制可能与其调节VDAC1、Mfn2和GRP75等MAM结构蛋白表达和影响细胞内钙平衡有关。

Effects of Mitofusin-2 Gene on Cell Proliferation and Chemotherapy Sensitivity of MCF-7

In order to evaluate the effect of mitofusin-2 gene （mfn2） on proliferation and chemotherapy sensitivity of human breast carcinoma cell line MCF-7 in vitro, pEGFPmfn2 plasmid carrying full length of mitofusin-2 gene was transfected, by using sofast, into MCF-7 cells. Mitofusin-2 gene expression in MCF-7 cells transfected by sofast after 48 h was detected by PCR and Western blotting, and the stable expression of GFP protein in MCF-7 cells by Western blot analysis. The proliferation of MCF-7 cells was assayed by MTT and cell counting. By using PI method, the effects of mfn2 on the cell cycle distribution of MCF-7 were measured. Annexin-Ⅴ/PI double labeling method was employed to detect the changes in apoptosis induced by chemotherapeutics before and after transfection. The results showed that the MCF-7 cells transfected with mfn2 gene could stably and highly express GFP protein. MTT assay revealed that after transfection of mfn2 cDNA, the proliferation of MCF-7 cells was significantly inhibited. DNA histogram showed that cells arrested in S phase, and the percentage of S phase cells was 42.7, 17.2 and 19.6 in mfn2 cDNA transfection group, blank plasmid transfection group and blank control group, respectively （P〈0.05）. The apoptosis ratio of the cells transfected with mfn2 gene was increased from 3.56% to 15.95%, that of the cells treated with camptothecin （CAMP） followed by mfn2 gene transfection was 69.6%, and that in blank plasmid transfection group and blank control group was 31.0% and 23.4% respectively （P〈0.05）. It was suggested that transfection of mfn2 gene could significantly inhibit the proliferation of MCF-7 cells and promote their sensitivity to CAMP with a synergic effect.

滋肾活血方对血管性痴呆大鼠分裂与融合蛋白Mfn1、Mfn2、Drp1、Fis1的影响

目的观察滋肾活血方对血管性痴呆(vascular dementia,VD)大鼠海马组织线粒体融合蛋白1(mitofusin 1,Mfn1)、线粒体融合蛋白2(mitofusin 2,Mfn2)、线粒体动力蛋白相关蛋白1(dynamin-related protein 1,Drp1)、线粒体分裂蛋白1(fission mitochondrial 1,Fis1)表达的影响。方法选用雄性SD大鼠60只,随机均分为假手术组、模型组、滋肾活血高剂量组、滋肾活血中剂量组、滋肾活血低剂量组、西药组。除假手术组外,其余各组均采用改良2-VO法建立VD大鼠模型。每组大鼠按9 mL/(kg·d)剂量灌胃相应药物。模型组、假手术组给予蒸馏水,滋肾活血低剂量组、滋肾活血中剂量组、滋肾活血高剂量组予以滋肾活血方溶液[9.8、17.8、35.6 g/(kg·d)]灌胃,西药组以多奈哌齐溶液[150 mg/(kg·d)]灌胃。连续喂药2周后,采用水迷宫实验评估大鼠学习记忆功能;取海马组织,采用免疫组化法检测实验大鼠海马组织中的Mfn1、Mfn2、Drp1、Fis1蛋白表达量。结果与假手术组比较,模型组大鼠逃避潜伏期(escape latency,EL)延长(P<0.05),Mfn1、Mfn2、Drp1蛋白的表达量降低(P<0.05)。与模型组对比,滋肾活血中、高剂量组大鼠EL缩短(P<0.05),Mfn1、Mfn2、Drp1蛋白表达量升高(P<0.05)。与滋肾活血低剂量组比较,滋肾活血中、高剂量组大鼠EL缩短(P<0.05),Mfn1、Drp1蛋白表达量升高(P<0.05)。结论滋肾活血方可能通过调节细胞内线粒体分裂与融合,上调Mfn1、Mfn2、Drp1蛋白的表达,从而改善认知功能。

Mitofusin-2 mediated mitochondrial Ca2+ uptake 1/2 induced liver injury in rat remote ischemic perconditioning liver transplantation and alpha mouse liver-12 hypoxia cell line models

AIM To investigate the protective mechanism of mitofusin-2 (Mfn2) in rat remote ischemic perconditioning (RIC) models and revalidate it in alpha mouse liver-12 (AML-12) hypoxia cell lines. METHODS Sprague-Dawley rats were divided into three groups (n = 6 each): sham, orthotopic liver transplantation and RIC. After operation, blood samples were collected to test alanine aminotransferase and aspartate aminotransferase. The liver lobes were harvested for histopathological examination, western blotting (WB) and quantitative real-time (qRT)-PCR. AML-12 cell lines were then subjected to normal culture, anoxic incubator tank culture (hypoxia) and anoxic incubator tank culture with Mfn2 knockdown (hypoxia + Si), and data of qRT-PCR, WB, mitochondrial membrane potential (Delta psi m), apoptosis, endoplasmic reticulum Ca2+ concentrations and mitochondrial Ca2+ concentrations were collected. RESULTS Both sham and normal culture groups showed no injury during the experiment. The RIC group showed amelioration of liver function compared with the orthotopic liver transplantation group (P < 0.05). qRTPCR and WB confirmed that Mfn2-mitochondrial Ca2+ uptake 1/2 (MICUs) axis was changed (P < 0.005). In AML-12 cell lines, compared with the hypoxia group, the hypoxia + Si group attenuated the collapse of..m and apoptosis (P < 0.005). The endoplasmic reticulum Ca2+ decrease and mitochondrial Ca2+ overloading observed in the hypoxia group were also attenuated in the hypoxia + Si group (P < 0.005). Finally, qRT-PCR and WB confirmed the Mfn2-MICUs axis change in all the groups (P < 0.005). CONCLUSION Mfn2 participates in liver injury in rat RIC models and AML-12 hypoxia cell lines by regulating the MICUs pathway.

线粒体融合素基因-2对人乳腺癌MCF-7细胞株增殖与化疗敏感性的影响

背景与目的:线粒体融合素基因-2(mitofusin-2gene,mfn2)是作用于线粒体外膜的一种增殖抑制基因,mfn2过表达可抑制血管平滑肌细胞的增殖。本研究探讨外源性mfn2对人乳腺癌细胞MCF-7增殖以及化疗敏感性的影响。方法:将含有mfn2cDNA的质粒在阳离子聚合物的介导下体外转染MCF-7细胞,Westernblot法检测绿色荧光蛋白(greenfluorescentprotein,GFP)的表达,细胞计数及MTT法检测mfn2对MCF-7细胞增殖的影响,流式细胞术检测MCF-7细胞周期分布及喜树碱处理前后细胞凋亡的变化。结果:转染mfn2基因的MCF-7细胞可以稳定高表达GFP。MTT实验提示转染mfn2cDNA后,MCF-7细胞增殖明显受到抑制,DNA直方图显示细胞停滞于S期,转染mfn2cDNA组S期细胞比率为(42.7±1.3)%,高于转染空质粒组的(17.2±2.0)%和空白对照组的(19.6±1.7)%(P<0.05)。mfn2基因转染后诱导的细胞凋亡率从(3.6±0.6)%升高到(16.0±0.3)%;加入喜树碱4h后转染mfn2基因的细胞凋亡率为(69.6±4.3)%,高于转染空质粒组的(31.0±1.8)%和空白对照组的(23.4±2.8)%(P<0.05)。结论:转染mfn2基因可以明显抑制MCF-7细胞的增殖,增强MCF-7细胞对喜树碱的敏感性。

线粒体融合蛋白2研究新进展

线粒体融合蛋白2(mitofusin-2,Mfn2)是一种高度保守的跨膜GTP酶,在线粒体融合中的关键作用已为人所熟知.随着认识的不断深入,Mfn2在介导线粒体融合之外的功能日渐显现,其在细胞信号转导、能量代谢、增殖及凋亡等生命过程中均具有重要调节作用.Mfn2效应的广泛性及作用机制的复杂性预示着其在现代生物医学中可能极具应用价值.综述了Mfn2结构和生物学功能研究的最新认识,并简要介绍了Mfn2功能或表达异常与疾病发生的关系及其治疗学意义.

EPO对缺血/再灌注损伤大鼠心肌细胞Mfn2蛋白表达及心肌细胞凋亡的影响

目的观察重组人促红细胞生成素(recombinant human erythropoietin,rhEPO)对缺血/再灌注损伤大鼠心肌细胞Mitofusin2(Mfn2)蛋白表达的影响及其抗心肌细胞凋亡的作用。方法选取成年SD大鼠35只,随机分为正常组(Normal),假手术组(Sham),缺血再灌注组(I/R),缺血再灌注EPO治疗组(I/R+EPO)。各组分别于再灌注3h和24h后,剪取心脏缺血/再灌注损伤区域,用脱氧核苷酸末端转移酶介导的缺口末端标记法(TUNEL)检测心肌细胞凋亡,免疫组化法检测Mfn2蛋白的表达。结果再灌注3h和24h后,与正常组和假手术组相比,I/R组Mfn2蛋白的表达和心肌细胞凋亡均显著增加;与I/R组相比,I/R+EPO组Mfn2蛋白的表达和心肌细胞凋亡均显著降低。结论EPO可以下调缺血再灌注损伤后心肌细胞Mfn2蛋白的表达,抑制心肌细胞的凋亡。

阿托伐他汀通过下调线粒体融合素2表达抑制大鼠心肌缺血再灌注后细胞凋亡

目的研究阿托伐他汀对大鼠心肌缺血再灌注(I/R)损伤后细胞凋亡及线粒体融合素2表达的影响。方法选取雄性SD大鼠32只,随机分为假手术组(sham),缺血再灌注组(I/R),阿托伐他汀1组(statin 1)和阿托伐他汀2组(statin 2),每组8只。Statin 1组术前7 d开始每日给予阿托伐他汀10 mg/(kg·d)灌胃,statin 2组药物剂量为40 mg/(kg·d),I/R组以等体积蒸馏水灌胃,随后制备心肌I/R损伤模型。各组于再灌注3 h后剪取心脏I/R损伤区域,脱氧核糖核苷酸末端转移酶介导的缺口末端标记法(TUNEL)检测细胞凋亡,免疫印迹法检测磷酸化蛋白激酶B(p-Akt)的表达,免疫组化法检测线粒体融合素2的表达。结果与sham组相比,I/R组及statin 1组、statin 2组心肌细胞凋亡显著增加,p-Akt表达显著下降,线粒体融合素2表达显著增加(P<0.01);与I/R组相比,statin 1组、statin 2组心肌细胞凋亡和线粒体融合素2表达均显著降低(P<0.05),而p-Akt表达显著增高(P<0.05),且statin 2组较statin 1组变化更显著(P<0.05)。结论阿托伐他汀可抑制大鼠心肌缺血再灌注损伤后的细胞凋亡,其作用可能与抑制线粒体融合素2表达有关。

胰岛素抵抗大鼠及恢复状态下PGC-1α和Mfn2表达的变化

目的观察胰岛素抵抗(IR)及改善后骨骼肌过氧化物酶体增生物激活受体γ共激活因子1α(PGC-1α)和线粒体融合蛋白2(Mfn2)的表达变化及线粒体形态和参数的变化。方法成年Wistar大鼠随机分为对照组(NC)、高脂组(HF)和高脂罗格列酮干预组(HF+RSG)。喂养4周及8周时,清醒状态下用正常葡萄糖高胰岛素钳夹技术评价IR;第8周时,实时定量PCR和Western blot检测骨骼肌PGC-1α和Mfn2的表达;透射电镜观察骨骼肌线粒体的形态;Im-age-Pro Plus 6分析线粒体的各项参数。结果高脂喂养4周后HF组与HF+RSG组IR状态形成。继续喂养4周后,HF+RSG组由于服用罗格列酮IR状态改善明显。与NC组相比,HF组的PGC-1α和Mfn2均显著下降(P<0.05);与HF组相比,HF+RSG组上述两基因的表达均显著升高(P<0.05);而与NC组相比,HF+RSG组PGC-1α的表达没有明显差异,而Mfn2的表达仍较低。与其余两组相比,HF组线粒体的形态和各项参数也发生了明显的改变(P<0.05)。结论胰岛素抵抗状态的形成与PGC-1α和Mfn2的表达下降有关,也与线粒体的改变有关。