心肌细胞裂解液对骨髓间充质干细胞向心肌细胞分化诱导作用的研究

目的通过向骨髓间充质干细胞(MSCs)培养体系中添加心肌细胞裂解液的方法,体外模拟心肌微环境,观察MSCs向心肌细胞分化的诱导作用,并与诱导分化剂5-氮杂胞苷(5-aza)比较。方法分离新生乳鼠的心肌细胞并制成心肌细胞裂解液,自成年大鼠骨髓中分离MSCs,用含有心肌细胞裂解液的培养基(A组)、含有5-aza的培养基(B组)、含有5-aza和心肌细胞裂解液的培养基(c组)以及普通培养基(对照组)培养。观察细胞形态的改变,并通过免疫组化分析分化后细胞表达α-肌动蛋白、心脏特异性肌钙蛋白T(cTnT)、连接蛋白43及CD31的情况。结果A、B组的MSCs在培养1周后均形成肌细胞形态,并且均表达α-肌动蛋白和cTnT;A组MSCs分化的肌样细胞所含的肌纤维较B组更丰实,细胞生长趋势也优于B组,并且可以表达CD31;B组MSCs分化的肌样细胞不表达CD31;对照组细胞仅表达α-肌动蛋白。结论心肌细胞裂解液是体外诱导MSCs分化为心肌样细胞的理想条件,优于传统的5-aza,在心肌细胞移植技术中可以用于体外模拟心肌细胞微环境。     

细胞因子对骨髓间充质干细胞增殖及其向心肌细胞分化的影响

目的探讨干细胞因子（SCF）和粒细胞集落刺激因子（G-CSF）预处理对骨髓间充质干细胞（MSCs）增殖分化的作用。方法将sD大鼠随机分成对照组、SCF组、G—CSF组和SCF＋G—CSF联合处理组。流式细胞仪检测第4代MsCs细胞周期。用DAPI（25mg／m1）标记的P4MSCs与心肌细胞共培养。在共培养的第1天至第5天用免疫荧光技术分别检测心肌特异性肌节肌球蛋白重链（MHC）、肌钙蛋白T（TnT）的表达，统计向心肌样细胞分化的MSCs百分率。结果（1）SCF和G—CSF联合应用能明显诱导MSCs进入S期，单因子SCF组和G-CSF组与对照组相比，也明显的促进MSCs由G0／G1期进入S期（P〈0．01）。（2）MSCs与心肌细胞共培养后，SCF和G—CSF联合组MSCs表达心肌特异性蛋白MHC及TnT的阳性百分率均显著增高，单细胞因子组MSCs的心肌特异性蛋白MHC及TnT的阳性表达亦较对照组高。结论SCF和G—CSF对MSCs具有促增殖、促分化的作用。     

类胚体形成对P19细胞向心肌细胞分化的影响

目的探讨类胚体(EBs)形成以及心肌细胞条件培养液对P19细胞向心肌细胞分化的影响。方法将P19细胞接种于铺有琼脂的6孔板中,形成EBs。用α-MEM培养液或心肌细胞条件培养液培养EBs或单层生长的P19细胞。观察细胞生长情况;免疫组化SP法检测心肌肌钙蛋白(cTnT)表达;Western blot法检测cTnT及心肌细胞缝隙连接蛋白43(Cx43)表达。结果单层培养的P19细胞未见cTnT及Cx43表达,免疫组化SP法检测示EBs经α-MEM培养液或心肌细胞条件培养液培养,生长晕中可见cTnT表达。Western blot法检测示心肌细胞条件培养液中cTnT和Cx43表达显著高于α-MEM培养液。结论 EBs形成结合心肌细胞条件培养液培养可有效促进P19细胞向心肌细胞分化,具体分化机制有待深入研究。     

诱导骨髓间充质干细胞向心肌样细胞分化的实验研究

目的 观察乳鼠心肌细胞条件培养液、SalB 、5-氮胞苷(5-aza)及SalB联合5-aza体外诱导骨髓间充质干细胞(MSCs)分化为心肌样细胞的作用及其机制.方法 分离培养及鉴定大鼠MSCs,培养乳鼠心肌细胞,收集条件培养液对其进行分组诱导:①SalB(终浓度为250 μg/L),②5-aza组(终浓度为10 μg/L),③SalB联合5-aza组(终浓度分别为250 μg/L与10 μmol/L),④乳鼠心肌细胞条件培养液,⑤未加诱导剂的阴性对照组.选取MSCs进行诱导,诱导周期为4 w.倒置相差显微镜下观察细胞的生长情况及形态变化,免疫细胞化学法鉴定心肌特异性肌钙蛋白T(cTnT)表达,实时荧光定量RT-PCR法检测心肌早期基因NKX2.5、GATA-4 mRNA的相对表达量.结果 细胞形态学显示,诱导后的MSCs体积增大,增殖减慢,并出现肌管样结构;免疫细胞化学结果显示,诱导后的MSCs表达心肌特异性蛋白cTnT,与5-aza组相比,SalB组和条件培养液两组蛋白表达较低,SalB联合5-aza组蛋白表达升高;实时荧光定量RT-PCR结果显示除阴性对照组外,其他四组表达心肌分化早期基因,SalB联合5-aza组诱导后的MSCs的心肌早期分化基因表达明显高于其他三组.结论 SalB联合5-aza诱导MSCs表达心肌特异性肌钙蛋白cTnT;上调心肌早期基因NKX2.5、GATA-4mRNA的表达,证实其能够向心肌细胞分化能力;条件培养液不能上调心肌细胞的早期基因和蛋白,不能诱导其分化.     

心肌细胞裂解成分诱导骨髓间充质干细胞分化的超微结构观察

目的:观察骨髓间充质干细胞(MSCs)在心肌细胞裂解成分作用下超微结构改变,了解心肌细胞裂解成分对MSCs分化的诱导作用。 方法:分离并裂解新生大鼠的心肌细胞;自成年大鼠骨髓中分离MSCs;将分离的MSCs分3组培养:仅用普通培养基培养(对照组);5-氮杂胞苷(5-aza)诱导后用普通培养基培养(5-aza诱导组);含有心肌细胞裂解成分的培养基培养(心肌细胞裂解成分培养组)。培养1周,观察细胞形态及超微结构的改变,对培养的细胞进行抗心脏特异性肌钙蛋白T(cTnT)及抗分化决定簇31(CD31)细胞免疫化学染色,并分析各组细胞的增殖情况。 结果:对照组MSCs无明显的肌样细胞或内皮样细胞形成,抗cTnT和抗CD31染色阴性。5-aza诱导组部分MSCs分化为肌样细胞,电镜下可见大量细胞器空化,抗cTnT染色阳性,但细胞增殖缓慢。心肌细胞裂解成分培养组的MSCs分化为肌样细胞,电镜下可见肌丝样结构,抗cTnT染色阳性,细胞增殖旺盛,另见部分MSCs分化为内皮样细胞,形成内皮细胞特有的胞质突起和质膜小泡等超微结构,且抗CD31染色阳性。 结论:含有心肌细胞裂解成分的培养基可以诱导MSCs向心肌样细胞和内皮样细胞方向分化。     

骨髓基质细胞的诱导分化及其移植对兔心肌梗死后的心功能的影响

目的采用骨髓基质细胞(MSCs)体外转化为肌细胞,为心力衰竭的细胞心肌成形提供较为理想的移植细胞. 方法从兔股骨头处抽取骨髓,用Ficoll细胞分离液分离MSC8,体外培养,经5-氮杂胞苷(5-aza)刺激24h后,用免疫组织化学方法检测肌源细胞中肌节肌动蛋白(actin)、肌钙蛋白Ⅰ(troponin Ⅰ)、结蛋白(desmin)和缝隙连接蛋白43(Cx43)的表达;用RT-PCR检测肌球蛋白重链(MHC)的基因表达;用电镜观察肌源细胞的超微结构.并将诱导分化后MSCs移植到结扎兔冠状动脉前降支致心肌梗死(MI)的模型中.     

骨髓间质干细胞体外诱导为心肌细胞的实验研究

目的:探讨骨髓间质干细胞(MSCs)体外诱导分化为心肌细胞的可行性,为心肌梗死治疗提供理想的细胞材料。方法:分离大鼠下肢骨获取MSCs进行培养;5-氮胞苷(5-aza)诱导24h后继续培养;免疫细胞化学检测细胞对连接蛋白-43和α横纹肌肌动蛋白的表达;逆转录-聚合酶链反应(RT-PCR)进一步了解心肌细胞特异性蛋白的表达。结果:MSCs经5-aza诱导后,细胞形态不规则;诱导后3周10μmol/L 5-aza组细胞连接蛋白-43、α横纹肌肌动蛋白表达阳性。RT-PCR显示10μmol/L 5-aza诱导后3周的细胞可表达心肌肌钙蛋白I、α心肌肌动蛋白。结论:MSCs体外经5-aza诱导后可分化为心肌细胞。     

自发性高血压大鼠肥厚左室心肌组织微小RNA-1与缝隙连接蛋白43的改变

目的观察自发性高血压大鼠(SHR)肥厚左室心肌组织微小RNA-1(miRNA-1)、缝隙连接蛋白43(Cx43)表达的变化及其关系,以探讨高血压性心肌肥厚发生室性心律失常(VA)的分子机制。方法 10只17周龄雄性SHR大鼠做为左室肥厚组(LVH组),10只8周龄雄性SHR大鼠做为对照组,通过病理学、心肌细胞横径的测量、实时荧光定量聚合酶链反应、免疫组织化学法及western blotting检测等方法 ,比较两组大鼠左室心肌组织病理学改变、miRNA-1及Cx43蛋白表达。结果①与对照组比较,LVH组的收缩压、舒张压升高,左室质量指数及心肌细胞横径均明显增大(P均0.05);miRNA-1表达水平明显升高,以及Cx43蛋白表达水平降低(0.27±0.10vs0.60±0.13,P0.05);②LVH组大鼠左室心肌组织miRNA-1与Cx43蛋白的表达水平呈显著负相关(r=-0.661,P0.05)。结论 miRNA-1可能通过抑制Cx43表达而参与高血压LVH发生VA。     

5-氮胞苷诱导间质干细胞为心肌细胞的实验研究

分离SD大鼠下肢骨，培养获得骨髓间质干细胞（MSCs），经5-氮胞苷（5-aza）定向诱导24h后t用免疫细胞化学法检测诱导细胞对连接蛋白43和α横纹肌肌动蛋白的表达，用逆转录-聚合酶链反应鉴定心肌细胞特异性蛋白的表达情况。结果显示，MSCs经5-aza诱导后，细胞形态不规则；3周后5-aza 10μm组细胞连接蛋白43、α横纹肌肌动蛋白阳性表达；RT-PCR显示细胞表达心肌肌钙蛋白Ⅰ、α心肌肌动蛋白。提示5-aza可体外诱导MSCs分化为心肌细胞，用于心肌梗死的治疗。     

心肌组织裂解液诱导骨髓间充质干细胞向心肌样细胞分化的研究

目的探讨心肌组织裂解液定向诱导骨髓间充质干细胞(BMSCs)分化为心肌样细胞的可行性。方法体外分离、培养及鉴定大鼠BMSCs,实验分为3组:空白对照组、正常心肌组织裂解液诱导组和梗死心肌组织裂解液诱导组。分别对第3代BMSCs进行定向诱导,倒置相差显微镜观察诱导后细胞形态变化。诱导4周后,Western-blot检测心肌肌钙蛋白T(cTnT)、心肌连接蛋白43(Cx43)的表达。结果 P3代BMSCs CD34染色呈阴性,而CD105、CD106染色呈阳性。两个诱导组cTnT、Cx43蛋白表达量均高于空白对照组,且梗死心肌裂解液诱导组的蛋白表达量高于正常心肌组织裂解液诱导组,差异有统计学意义(P0.05)。结论正常心肌组织裂解液及梗死心肌组织裂解液均可诱导BMSCs分化为心肌样细胞,且梗死心肌组织裂解液组诱导分化效率更高。     

Transdifferentiation of mesenchymal stem cells into cardiomyocytes by direct cell-to-cell contact with neonatal cardiomyocyte but not adult cardiomyocytes

Recent studies have demonstrated that direct cell-to-cell interaction is one of the microenvironment factors for transdifferentiation of adult stem cells into cardiomyocytes. We investigated whether transdifferentiation of mesenchymal stem cells (MSCs) into cardiomyocytes was dependent on developmental stages of cocultured cardiomyocytes, and direct cell-to-cell interaction was essential for transdifferentiation. MSCs were isolated from adult rat and cocultured in four different ways: (1) with neonatal cardiomyocytes, (2) with adult cardiomyocytes, (3) with neonatal cardiomyocytes on the cell culture inserts, and (4) with the conditioned medium from neonatal cardiomyocytes. After 5 days of coculture with neonatal cardiomyocytes, 9.40±1.15% of 1,1-dioctadecyl-1-3,3,3,3-tetramethylindocarbocyanine perchlorate labeled MSCs expressed sarcomeric--actinin. Immunocytochemistry showed that only these MSCs expressed the cardiac markers and were not observed with other coculture condition as well as conditioned medium. Calcein-AM labeling of cardiomyocytes showed gap junctional communication between 56.1±2.0% of MSCs (24 h after labeling, n=5) and neonatal cardiomyocytes. These findings suggest that MSCs are capable of differentiating into cardiomyocytes when directly cocultured with neonatal cardiomyocytes by cell-to-cell interaction, but not with adult cardiomyocytes or conditioned medium.     

Cell-to-cell contact induces mesenchymal stem cell to differentiate into cardiomyocyte and smooth muscle cell

BACKGROUND: Recent evidences have suggested that stem cell can differentiate into cardiomyocyte and smooth muscle cell (SMC) in vivo or in vitro. But the mechanism on how stem cell differentiates is still unknown. We investigated whether intercellular interaction or soluble chemical factors would induce mesenchymal stem cells (MSCs) to acquire the phenotypical characteristics of cardiomyocytes or SMC. METHODS: MSCs were isolated from rat bone marrow with density gradient centrifugation and amplified in vitro. Flow cytometry was used to monitor the expression of surface antigen profile. After labeled by GFP (green fluorescent protein) transfection, rat MSCs were used to culture with adult rat cardiomyocytes and rat aortic SMCs in direct co-culture, indirect co-culture and conditioned culture, respectively. One week later, immunofluorescence staining against alpha-actin, desmin, and cardiac troponin T (cTnT) for cardiomyocyte, smooth muscle calponin and SM-alpha-actin for SMC were performed. RESULTS: Immunofluorescence staining was positive against alpha-actin, desmin, and cTnT on MSCs in co-culture group with adult cardiomyocytes, positive against smooth muscle calponin and SM-alpha-actin on MSCs in co-culture group with SMCs. In contrast, no alpha-actin, desmin, and cTnT expression was observed in the indirect co-culture group and conditioned culture group; no smooth muscle calponin and SM-alpha-actin in the indirect co-culture group and conditioned culture group. CONCLUSIONS: Direct cell-to-cell contact between MSC and adult cardiomyocyte or SMC, but not the soluble signaling molecules is obligatory in the differentiation of MSC into cardiomyocytes or SMC.     

缺氧对肥大心肌细胞凋亡和缝隙连接蛋白43表达的影响

目的探讨缺氧对正常心肌细胞和肥大心肌细胞缝隙连接蛋白43(Cx43)表达的影响。方法将培养的乳鼠心肌细胞或诱导肥大后的心肌细胞分别缺氧24 h,并以Hoechst33258染色法检测缺氧对心肌细胞凋亡的影响,Western blot和免疫荧光法检测Cx43的表达。结果培养的心肌细胞经血管紧张素Ⅱ诱导48 h后出现肥大,肥大心肌细胞缺氧24 h比正常心肌细胞出现更明显的凋亡,缺氧明显下调心肌细胞Cx43的表达,而肥大心肌细胞Cx43的表达下调更为明显。结论缺氧导致肥大心肌细胞Cx43的表达显著下调,细胞凋亡更明显,可能与缺氧时肥大心肌的电生理重构和恶性心律失常的产生机制有关。     

间接接触共培养下骨髓间充质干细胞分化为心肌样细胞及相关调控基因的时序表达

目的:研究间接接触共培养条件下骨髓间充质干细胞(mesenchymal stem cells,MSCs)向心肌细胞(myocadium-lkce cells,CMs)的分化及相关调控基因的时序表达;筛选MSCs定向分化为CMs的重要调控基因。方法:将MSCs与CMs按1∶5的比例进行间接接触共培养,连续观察两周,在相差显微镜下观察MSCs的形态变化。采用免疫荧光染色法检测心肌特征性肌动蛋白α(α-actin)和心脏肌钙蛋白T(cTnT)的表达。应用半定量RT-PCR分析TGF-β、Nkx-2.5、GATA-4、MEF-2C及TEF-1等相关调控基因在分化过程中的时序表达。结果:共培养后,MSCs的体积增大,其梭形形态逐渐变短变粗近似棒状或椭圆形,细胞之间形成连接,排列方向趋于一致。共培养两周时,α-actin及cTnT阳性细胞的比例分别为29.63%和27.38%。TGF-β、Nkx-2.5、GATA-4和MEF-2C基因在共培养后1 d表达开始增强,诱导后7 d达高峰,以后虽有所下降但仍维持在较高水平;TEF-1基因在诱导过程中表达无明显变化。结论:间接接触共培养条件下,MSCs可分化为心肌细胞。在此过程中,TGF-β、Nkx-2.5、GATA-4和MEF-2C基因可能是调控MSCs定向分化为心肌样细胞的重要调控基因。     

Cardiomyocyte-restricted deletion of connexin43 during mouse development

Although the gap junction protein Connexin43 (Cx43) is expressed in various cell types during embryonic development, mice with a global inactivation of Cx43 survive until birth but die perinatally due to an obstruction of the right ventricular outflow tract of the heart. To analyze the functional role of Cx43 gap junction channels in cardiomyocytes of the developing and early postnatal heart, we used alphaMyHC-Cre mice to ablate Cx43 expression selectively in cardiomyocytes during development. We found efficient ablation of Cx43 in cardiomyocytes during embryonic development starting at embryonic day (ED) 9.5 in the ventricular wall. Analyses of cardiac Cx43 protein at birth indicated complete loss of Cx43 expression in cardiomyocytes. All mice homozygously deficient for Cx43 in cardiomyocytes died until postnatal day (PD) 16. Heterozygous inactivation of Cx43 in cardiomyocytes neither altered atrial nor ventricular activation, but homozygous ablation led to changes in ventricular activation, i.e. significant decrease of the QRS-amplitude and prolonged QRS-duration already at PD 4. Cardiac morphology was similar to controls until PD 1, but subtle morphological changes were found in a subgroup of mutant mice at later stages. Besides narrowing of the ventricular outlet region at PD 6, hypertrophy of ventricular myocardium was found at PD 12. Our data indicate that complete inactivation of cardiac Cx43 during development predisposes hearts to develop postnatal morphological alterations, which differ from outflow tract obstructions described for Cx43 null mice. In addition, complete loss of cardiac Cx43 protein during development correlates with slowed ventricular activation at PD 4, impairs viability during development, and leads to death of all mutant mice until PD 16.     

Cardiomyocyte-restricted deletion of connexin43 during mouse development

Although the gap junction protein Connexin43 (Cx43) is expressed in various cell types during embryonic development, mice with a global inactivation of Cx43 survive until birth but die perinatally due to an obstruction of the right ventricular outflow tract of the heart. To analyze the functional role of Cx43 gap junction channels in cardiomyocytes of the developing and early postnatal heart, we used αMyHC-Cre mice to ablate Cx43 expression selectively in cardiomyocytes during development. We found efficient ablation of Cx43 in cardiomyocytes during embryonic development starting at embryonic day (ED) 9.5 in the ventricular wall. Analyses of cardiac Cx43 protein at birth indicated complete loss of Cx43 expression in cardiomyocytes. All mice homozygously deficient for Cx43 in cardiomyocytes died until postnatal day (PD) 16. Heterozygous inactivation of Cx43 in cardiomyocytes neither altered atrial nor ventricular activation, but homozygous ablation led to changes in ventricular activation, i.e. significant decrease of the QRS-amplitude and prolonged QRS-duration already at PD 4. Cardiac morphology was similar to controls until PD 1, but subtle morphological changes were found in a subgroup of mutant mice at later stages. Besides narrowing of the ventricular outlet region at PD 6, hypertrophy of ventricular myocardium was found at PD 12. Our data indicate that complete inactivation of cardiac Cx43 during development predisposes hearts to develop postnatal morphological alterations, which differ from outflow tract obstructions described for Cx43 null mice. In addition, complete loss of cardiac Cx43 protein during development correlates with slowed ventricular activation at PD 4, impairs viability during development, and leads to death of all mutant mice until PD 16.     

缺血预处理对大鼠缺血再灌注后心房肌Cx43和Cx40的影响

目的 探讨缺血预处理对大鼠缺血再灌注后的心房肌缝隙连接蛋白43(Cx43)和缝隙连接蛋白40(Cx40)表达和分布的影响。方法 30只Wistar大鼠随机分为假手术组(或对照组,n=5)：只穿线不结扎左冠状动脉前降支。缺血再灌注组(I/R组,n=5)：给予前降支结扎30 min,再灌注120 min。早期缺血预处理组(IPC组,n=5)：行IPC处理后,余处理同I/R组。延迟IPC组(L-IPC组,n=5)：在IPC处理24h后,余处理同I/R组。早期远程缺血预处理组(RIPC组,n=5)：给予RIPC后,余处理同I/R组。延迟RIPC组(L-RIPC组,n=5)：RIPC处理24h后,余处理同I/R组。测量心房组织Cx40、43的mRNA表达、Cx40、43蛋白表达以及用免疫组化法测定Cx40、43的分布。结果 I/R组Cx43和Cx40在mRNA水平和蛋白水平均明显降低,分布无规律且侧面分布相对增加。而各种IPC方式(IPC、L-IPC、RIPC、L-RIPC)在I/R后,心房Cx43和Cx40mRNA水平和蛋白水平下降不明显,其分布多于心肌细胞闰盘处,仅少量分布于心肌细胞侧面。结论 IPC能维持I/R后的心房肌Cx43和Cx40的较高表达,并维持其空间分布相对稳定。     

Proliferation of neonatal cardiomyocytes by connexin43 knockdown via synergistic inactivation of p38 MAPK and increased expression of FGF1

Gap junctions are intercellular channels that connect the cytoplasm of adjacent cell. Gap junctional intercellular communication has long been postulated to contribute to the maintenance of tissue homeostasis. Recent studies, however, have demonstrated that connexins, gap junction proteins, are involved in the regulation of a variety of cellular functions other than intercellular communication. Although, in neonatal rat ventricular myocytes, connexin-40, -43, and -45 are all expressed, connexin43 (Cx43) is the primary subtype. In this study, we examined whether and if so how the knockdown of a gap junction protein Cx43 with siRNA produced changes in the proliferative activity of neonatal cardiomyocytes. Cx43-knockdown resulted in a significant increase in the proliferation of cardiomyocytes. To clarify the mechanisms behind this increase, we investigated whether the activity of mitogen-activated protein kinases (MAPKs) changed on knockdown of Cx43. The knockdown decreased the expression of phosphorylated p38 (p-p38) MAPK. In addition, treatment of cardiomyocytes with a p38 MAPK inhibitor significantly increased the proliferative activity. Cultures were then co-treated with an inhibitor of p38 MAPK and fibroblast growth factor-1 (FGF1), since Cx43-knockdown significantly increased cytosolic FGF1 expression as well. The co-treatment enhanced the proliferation of cardiomyocytes compared with the treatment with the p38 MAPK inhibitor alone. Taken together, the present study demonstrated that Cx43-knockdown produced a significant increase in the proliferation of neonatal cardiomyocytes.     

缬沙坦抑制血管紧张素Ⅱ刺激下心肌细胞缝隙连接蛋白43表达的上调

目的研究血管紧张素Ⅱ(AngⅡ)刺激心肌细胞肥大后,缝隙连接蛋白43(Cx43)表达的变化及缬沙坦的干预作用。方法分离培养大鼠心肌细胞,分为对照组,AngⅡ组(AngⅡ1.0×10~6mol/L)和缬沙坦组(AngⅡ1.0×10~6mol/L+缬沙坦1.0×10~6mol/L)。另外将缬沙坦以1.0×10~5、1.0×10~6和1.0×10~7mol/L刺激分为A组、B组和C组。先用AngⅡ诱导心肌肥大24 h后,采用免疫荧光法和免疫印迹蛋白法观察心肌细胞Cx43蛋白表达以及缬沙坦的干预作用。结果与对照组比较,AngⅡ组心肌细胞明显肥大,蛋白质含量明显增加,Cx43蛋白表达明显上调;与AngⅡ组比较,缬沙坦组拮抗AngⅡ刺激下Cx43蛋白的上调,并呈明显浓度依赖性下降。与A组比较,B、C组Cx43蛋白表达下降(P<0.05)。结论 AngⅡ刺激心肌细胞24 h后,通过AngⅡ1型受体信号通路,导致Cx43蛋白表达浓度依赖性上调,缬沙坦明显抑制其上调,Cx43上调可能与心肌肥大过程有关。     

Gap junctions and the connexin protein family

Gap junctions (Gj) form conduits between adjacent cells that are composed of connexin (Cx) protein subunits and allow direct intercellular communication. To date, the connexin gene family comprises 20 members in the mouse and 21 members in the human genome, 19 of which can be grouped as sequence-orthologous pairs. The structure of connexin genes is relatively simple. An untranslated exon 1 is separated by an intron of different length from exon 2, containing the uninterrupted coding region and the 3'-untranslated region (3'-UTR). However, in some connexin genes, the untranslated regions and the reading frame are spliced. Among the known "cardiovascular" connexins, Cx37 and Cx40 were demonstrated to be functionally expressed in mouse and human endothelial cells and Cx40, Cx43 as well as Cx45 in cardiomyocytes of both species. Functional properties, like permeabilities, charge selectivity and unitary conductivity were investigated after directed expression of these connexins in cultured cell lines or paired Xenopus oocytes. Targeted deletion of their coding sequence in the mouse genome allowed study of the biological relevance of Cx37, Cx40, Cx43 and Cx45 with regard to cardiovascular morphology and function. After ablation of Cx37 or Cx40, mice were viable and could be used to study defects in the adult cardiovascular system but loss of Cx43 or Cx45 led to neonatal or embryonic lethality, respectively. Conditional and cell-type specific deletion of both connexins in the heart or blood vessels can help to overcome this obstacle. As yet only little is known about mutations in the human genes for Cx37, Cx40, Cx43 and Cx45. Thus, a profound comparison between human and mouse phenotypes is not yet possible.