溶血磷脂酸对幼年大鼠心肌细胞收缩和钙瞬变的影响

目的我们前期的研究发现LPA受体在幼年大鼠心脏的表达显著高于成年的表达,提示LPA信号在心脏收缩功能尚未成熟时可能具有更为重要的调节作用。本研究通过观察LPA对此未成熟阶段心肌细胞钙瞬变和收缩力的作用,探讨LPA信号对幼年心肌兴奋-收缩耦联的影响。方法 Langendorff装置逆向灌流胶原酶分离获得不同发育阶段大鼠心肌细胞;采用IonOptix细胞收缩和钙离子浓度同步测定系统进行心肌细胞收缩力和钙瞬变的测定;Western blot检测不同发育阶段心肌细胞LPA受体的表达。结果 LPA对出生后14天和21天大鼠心肌细胞的收缩和钙瞬变均没有显著影响,表明LPA信号并不参与出生后14-21天大鼠心肌细胞的兴奋-收缩耦联过程和心肌细胞收缩。在大鼠出生后发育过程中,LPA受体在心肌细胞的表达在出生后14天已显著下调,不同于在整体心脏表达下调的时间点(P21d),这可能是LPA对此发育阶段心肌细胞的收缩和钙瞬变均不产生影响的原因,提示在出生后14天LPA信号对心肌细胞的发育调节功能可能即已减弱或消失。结论 LPA信号对出生后14天及之后心肌收缩和钙瞬变无显著影响,但尚不能排除LPA对出生后更早期的未成熟心肌细胞收缩和兴奋-收缩耦联的作用。     

TNNI3K基因过表达诱导小鼠胚胎干细胞向心肌细胞分化

目的研究肌钙蛋白Ⅰ相关激酶(TNNI3K)对小鼠胚胎干细胞(m ESC)向心肌细胞分化的影响。方法从形态和细胞免疫荧光、碱性磷酸酶试验以及HE染色鉴定m ESC的多能性。采用悬滴法培养m ESC形成拟胚体(EB),自分化为跳动的心肌细胞,通过细胞免疫荧光和透射电镜(TEM)方法鉴定。慢病毒分别携带h TNNI3K基因和siRNA感染m ESC,并分别自分化为心肌细胞,通过流式细胞术(FCM)、细胞免疫荧光、Western blot等分析心肌特异性蛋白表达水平的差异。结果 m ESC表面蛋白分子SSEA-1和Oct-4表达呈阳性(绿色),ALP试验呈蓝紫色,核质比1。正常自分化的细胞免疫荧光显示cTnⅠ、cTnT、MLC2以及α-actinin阳性(绿色),肌节清晰可见。TEM显示心肌细胞独有的肌纤维亚细胞结构。过表达组cTnT+阳性细胞率高于对照组,Western blot显示心肌特异性蛋白cTnT、cTnⅠ、MLC2、α-actinin等显著高于对照组,且细胞免疫荧光结果显示MHC6蛋白提前表达。干扰组不仅cTnT+阳性细胞率显著低于对照组,而且心肌特异蛋白也显著低于对照组,MHC6蛋白表达延后。结论TNNI3K基因能增强心肌细胞的生成,促进m ESC向心肌细胞的分化。     

肥厚型心肌病心肌肌钙蛋白Ⅰ R145W突变对大鼠心肌细胞钙调控的影响

目的探讨国人新的致肥厚型心肌病（HCM）心肌肌钙蛋白Ⅰ基因突变（cTnⅠ R145W）引起HCM发病的可能机制。方法采用定点突变技术在大鼠cTnⅠ cDNA引入R146W（相当于人R145W）突变,增强型绿色荧光蛋白（EGFP）做报告基因,构建含野生型和突变型大鼠cTnⅠ cDNA的重组腺病毒载体。Langendoff逆流灌注系统分离成年大鼠心肌细胞,无血清法培养后重组腺病毒转染。Western blot检测重组蛋白的表达,全膜片钳技术记录心肌细胞膜L型钙电流,Fura-2／AM孵育后测定细胞内游离钙离子浓度和咖啡因诱导的肌浆网钙释放。结果DNA测序证实R146W突变成功引入大鼠cTnⅠ cDNA。新鲜分离的成年大鼠心肌细胞存活率达70％～80％,无血清培养7天后绝大部分能保持长杆状形态。重组腺病毒转染48h后荧光显微镜下可观察到绿色荧光,cTnⅠ和绿色荧光蛋白单抗均能检测到重组蛋白。与野生型cTnⅠ和正常对照组比较,突变型cTnⅠ组心肌细胞膜L型钙电流峰值明显降低。Fura-2／AM法测定细胞内游离钙离子浓度和咖啡因诱导的肌浆网钙释放,三组之问差异无统计学意义。结论含R146W突变的cTnⅠ蛋白可能引起心肌细胞的电生理学重构,进一步研究可探讨肌丝对钙的敏感性及钙调节蛋白表达的改变。     

成年大鼠心室肌细胞的急性分离方法

目的介绍一种新型的成年大鼠心肌细胞的急性分离方法。方法麻醉大鼠后快速取心脏,为心脏先循环灌流无钙台氏液,后循环灌流酶液,酶解完成后取左心室,迅速置于含0.5 mg/ml BSA的KB液(恒温37℃)中拉碎,吹打数次后离心,去上清,温育在含0.5 mg/ml BSA的KB溶液中35 min,梯度复钙。结果首次分离细胞存活率在80%~90%,复钙完成仍有40%~50%的细胞维持杆状,横纹清晰且90%以上细胞处于静止状态。结论通过该方法可获得稳定、高比例的存活心肌细胞,能够为成年大鼠心肌细胞原代培养及电生理学研究提供高品质细胞。     

大鼠心肌细胞急性分离方法及影响因素探讨

目的探讨酶解法急性分离大鼠心肌细胞的相关影响因素。方法采用改良Langendorff主动脉逆行灌流法对大鼠全心工作细胞进行酶解分离,分析分离过程中的诸多条件,从中优化最佳的分离方案,为膜片钳实验提供合格细胞。结果分离所用灌流液pH值为7.35~7.40,分离细胞的存活率最高。不同复钙方法对后续细胞存活有明显影响。三步梯度复钙后的细胞存活率明显高于一步、二步复钙法。细胞分离时,灌流速度对细胞存活率有较大影响,3mL/min流速时细胞存活率最高,不同灌流流程对分离细胞的质和量较大影响。采用钙-无钙台氏液先后灌流后再行酶解分离方式可获得长杆状、棱角分明、立体感强的心肌细胞,该细胞复钙后存活率为(56.8±2.6)%;直接使用无钙台氏液灌流后再行酶解分离方法获得(57.2±3.3)%的心肌细胞,其复钙后存活率为(36.7±3.5)%,前述方法明显优于后者。结论灌流液的pH值、灌流速度、细胞分离后的复钙方法及不同的灌流流程等因素可对大鼠心肌细胞的急性分离结果产生显著影响。     

LPS引起心肌细胞肌浆网钙漏流的机制及在内毒素心功能损伤中的作用

目的探究LPS引起心肌细胞肌浆网钙漏流的机制及在内毒素心功能损伤中的作用。方法应用膜片钳和激光共聚焦显微成像技术对LPS诱导的败血症休克大鼠心室肌细胞电生理活动以及钙信号的变化及其机制进行研究。结果(1)LPS引起心肌细胞收缩抑制;(2)LPS引起心肌细胞收缩偶联效率降低;(3)LPS引起钙火花发放增加。结论在LPS诱导的败血症休克大鼠模型上,心肌细胞RyR活动增加,钙火花发放增加,肌浆网钙漏流增强,肌浆网钙库容量部分耗竭,胞浆钙蓄积,心肌收缩抑制,导致心功能不全。     

Junctophilin-2表达下调介导心肌细胞兴奋—收缩耦联结构与功能的重塑

目的阐明横管(T-tubule,TT)与肌质网(sarcoplasmic reticulum,SR)耦联关键蛋白junctophilin-2(JP2)的表达下调对心肌细胞二联体超微结构以及兴奋-收缩耦联功能的影响。方法通过构建JP2特异性shRNA腺病毒敲减成年大鼠心肌细胞中JP2的表达后,采用透射电子显微镜观测心肌细胞横管和肌质网二联体结构的形态变化,并进一步采用全细胞膜片钳结合激光共聚焦钙成像技术检测心肌细胞兴奋收缩联联功能的变化。结果通过腺病毒敲减心肌细胞JP2表达后,心肌细胞内总TT数目、TT与SR耦联的二联体结构数目以及单个耦联子内耦联SR的TT长度占TT周长的百分比均显著降低;与此同时,JP2表达下降后心肌细胞钙瞬变幅度降低,收缩功能减弱,表现出与心力衰竭类似的表型。结论心肌细胞JP2表达下降引起心肌细胞兴奋-收缩耦联结构与功能的损伤,为心力衰竭病理情况下心肌细胞结构与功能的调控机制提供了直接有力的实验证据。     

利用CASAAV技术诱导心肌特异性Meis1敲除实现心肌原位增殖

目的 探讨基于CRISPR/Cas9/AAV的体细胞突变（CRISPR/Cas9/AAV-based somatic mutagenesis, CASAAV）技术诱导心肌细胞Meis1基因的特异性敲除实现小鼠心肌细胞原位增殖的可行性。方法 设计两条靶向小鼠Meis1基因的sg RNA序列逐个克隆至p AAV-U6g RNA1-U6g RNA2-Tn T-Cre载体中,并包装成腺相关病毒。分离RosaCas9EGFP/Cas9EGFP基因敲入小鼠的乳鼠心肌细胞和心脏成纤维细胞进行病毒的体外感染,利用细胞免疫荧光染色检测病毒的心肌特异性。给予RosaCas9EGFP/Cas9EGFP基因敲入小鼠的乳鼠胸腔内注射病毒进行体内感染,3周后利用心脏灌流技术分离心肌细胞,利用细胞免疫荧光染色检测病毒的心肌特异性和心肌细胞的增殖水平,利用一代测序技术和实时PCR技术分别检测心肌细胞中Meis1基因的编辑水平及Meis1基因和细胞周期相关基因的mRNA相对表达量;同时制作心脏组织切片并利用组织免疫荧光染色检测心脏组织中增殖标志物KI67、PH3及AURKB的蛋白表达水平。结果 腺相关病毒可特异性诱导心...     

胚胎期及出生后不同年龄段小鼠心肌细胞体外分离方法及优化

目的:基于目前已有报道的心肌细胞体外消化及分离方法,对胚胎期及出生后不同年龄段小鼠心肌细胞体外分离的方法进行系统探索和优化。方法:取胚胎期及出生后不同年龄段小鼠心脏,运用不同方法分离心肌细胞。利用Count Star仪器检测心肌细胞大小及活性。取细胞悬液涂片,针对心肌细胞标志物α辅肌动蛋白(α-actinin)表达进行免疫荧光染色,用共聚焦显微镜观察心肌细胞形态。结果:用胰酶消化法分离胚胎期小鼠心肌细胞,获得存活率大于94%的心肌细胞。用心脏解离试剂盒法(Gentle MACS法)体外分离新生小鼠(出生后1～3 d)心肌细胞,获得存活率约为97%的心肌细胞。分别用Gentle MACS法、非Langendorff灌流法分离出生后4 d和7 d的小鼠心肌细胞,前者仅获得存活率为58%的心肌细胞,而后者获得的心肌细胞存活率为70%～80%。对于成年小鼠,非Langendorff灌流法和Langendorff灌流法均可获得杆状率、存活率都在70%左右的心肌细胞。结论:结合文献以及本实验结果发现,分离胚胎期小鼠心肌细胞可用胰酶消化法;分离出生后1～3 d小鼠心肌细胞可用Gentle MACS法。对于出生后4 d和7 d的小鼠,非Langendorff灌流法可获得存活率及杆状率均较高的心肌细胞,分离成年小鼠心肌细胞则适合用非Langendorff灌流法和Langendorff灌流法。     

心肌细胞感染病毒后钙、钾通道电流及其表达改变和牛磺酸的作用

目的 观察心肌细胞感染病毒后心肌细胞钙，钾通道电流及通道表达改变和牛磺酸的作用。方法 （1）体外心肌细胞感染病毒；用胰蛋白酶和胶原酶消化法分别获得大鼠，乳鼠培养和分离的心肌细胞并感染柯萨奇B3病毒，用于检测Ca^2 跨膜内流，电压依赖性钙通道电流（Lca)和外向钾通道电流（Iout)。（2）在体小鼠感染病毒；BALB/c小鼠腹腔内注射柯萨奇B3病毒7d后取出心脏用于检测电压堆呀性钙通道α1亚单位抗原和电压调控性钾通道（Kv)mRNA的表达。相应各组加入不同剂量的牛磺酸并观察其作用。结果 （1）感染柯萨奇B3病毒后Ca^2 跨膜内流量及Ica增加，牛磺酸对其有抑制作用。（3）柯萨奇B3病毒感染out明显增大。牛磺酸可使病毒感染后的Iout趋于恢复正常。（3）柯萨奇B3病毒感染后小鼠心肌出现强电压依赖性钙通道α1亚基抗原阳性信号。Kv1.2,Kv2.1,Kv4.2mRNA与3种探针的杂交信号亦明显增强，牛磺酸可使增强的阳性信号减弱。结论 柯萨奇B3病毒感染后心肌细胞钙，钾离子通道电流及表达均增加，牛磺酸可通过抑制其改变而发挥对感染病毒心肌细胞的保护作用。     

Evidence,hypotheses and significance of MAP kinase TNNI3K interacting with its partners

TNNI3K is a cardiac-specific and cardiac troponin I (cTnI)-interacting MAP kinase, known to play important roles in promoting cardiac differentiation, maintenance of beating rhythm and contractual force. The molecular structure of TNNI3K contains three kinds of domain: a seven or ten NH₂-terminal ankyrin repeat domain followed by a protein kinase domain and a COOH-terminal serine-rich domain. There are many binding sites in the structure of TNNI3K for binding to ATP, magnesium, nucleotide, protein kinase C, antioxidant protein 1 (AOP-1) and cTnI, indicating TNNI3K has many interacting partners. This review summarizes the evidence, hypothesis and significance of TNNI3K interacting with TNNI3 and its other putative interaction partners. From the literature, the interaction partners of TNNI3K are divided into 2 types following their phenotypic pattern of functions, positive interaction (to increase the cardiac performance) or negative interaction (to suppress the cardiac performance). Following their binding sites, it also can be divided into other 2 types: binding to C-terminal domain (e.g., cTnI) or binding to both ankyrin repeat domain and C-terminal domains (AOP-1). To date, a well understood partner of TNNI3K is cTnI, from the molecular structure, physiological function, mechanisms and its significance in some physiological and pathophysiological conditions. There are many reasons to believe that, with more understanding on the TNNI3K interacting with its partners, we can understand more roles of TNNI3K in some cardiac diseases.     

肥厚型心肌病心肌肌钙蛋白Ⅰ相关激酶TNN13K基因突变的研究

目的对肥厚型心肌病患者进行TNNI3K基因进行测序分析,探讨此范围内有无基因突变位点。方法对56例无血缘关系的肥厚型心肌病患者及30名健康对照者的TNNI3K基因第18～19及23外显子进行聚合酶链反应扩增产物,设计内引物直接测序,观察有无基因突变,并对发生突变的患者进行临床特点分析。结果肥厚型心肌病患者及正常对照者在TNNI3K基因第18～19及23外显子未发现突变位点。结论目前在中国人群肥厚型心肌病患者中未发现TNNI3K基因突变位点。     

Novel mutation in cardiac troponin I in recessive idiopathic dilated cardiomyopathy

Idiopathic dilated cardiomyopathy is a common cause of heart failure. Half of cases are believed to be hereditary, and mutations in cardiac sarcomeric contractile protein genes have been reported with autosomal dominant inheritance. We used mutation analysis suitable for identification of both dominant and recessive mutations to investigate the sarcomeric gene for cardiac troponin I (TNNI3) in 235 patients with dilated cardiomyopathy. We identified a novel TNNI3 mutation in a family with recessive disease. Functional studies showed impairment of troponin interactions that could lead to diminished myocardial contractility. TNNI3 is the first recessive gene identified for this condition, and we suggest that other such genes could be pinpointed by mutation analyses designed to identify homozygous mutations.     

TNNI3K in cardiovascular disease and prospects for therapy

Cardiovascular diseases are an important cause of morbidity and mortality worldwide and the global burden of these diseases continues to grow. Therefore new therapies are urgently needed. The role of protein kinases in disease, including cardiac disease, is long recognized, making kinases important therapeutic targets. We here review the knowledge gathered in the last decade about troponin I-interacting kinase (TNNI3K), a kinase with cardiac-restricted expression that has been implicated in various cardiac phenotypes and diseases including heart failure, cardiomyopathy, ischemia/reperfusion injury and conduction of the cardiac electrical impulse.     

Frequency and clinical expression of cardiac troponin I mutations in 748 consecutive families with hypertrophic cardiomyopathy

OBJECTIVES: The aim of this study was to evaluate the potential utility of genetic diagnosis in clinical management of families with hypertrophic cardiomyopathy (HCM) caused by mutations in the gene for cardiac troponin I (TNNI3). BACKGROUND: Knowledge about the clinical disease expression of sarcomeric gene mutations in HCM has predominantly been obtained by investigations of single individuals (probands) or selected families. To establish the role of genetic diagnosis in HCM families, systematic investigations of probands and their relatives are needed. METHODS: Cardiac troponin I was investigated by direct sequencing and fluorescent (F)-SSCP analysis in 748 consecutive HCM families. Relatives of HCM probands with TNNI3 mutations were invited for cardiovascular and genetic assessment. RESULTS: The prevalence of TNNI3 mutations was 3.1%. Mutations appeared to cluster in exons 7 and 8. A total of 100 mutation carriers were identified in 23 families with 13 different mutations (6 novel). Disease penetrance was 48%. Patients were diagnosed from the second to eighth decade of life. The morphologic spectrum observed represented a wide range of HCM. Two offspring of clinically unaffected mutation carriers were resuscitated from cardiac arrest, and an additional four individuals died suddenly as their initial presentation. Six individuals experienced other disease-related deaths. CONCLUSIONS: The clinical expression of TNNI3 mutations was very heterogeneous and varied both within and between families with no apparent mutation- or gene-specific disease pattern. The data suggest that disease development may be monitored by regular assessment of cardiac symptoms and electrocardiographic abnormalities. Genetic diagnosis of TNNI3 is valuable in identifying clinically unaffected mutation carriers at risk of disease development and facilitates accurate management and counseling.     

心脏肌钙蛋白I-R145W突变所致肥厚型心肌病表型特点分析

目的明确心脏肌钙蛋白I(cTnI)R145W突变的表型特点。方法在300例肥厚型心肌病(HCM)患者及120例正常对照中对心脏肌钙蛋白I基因(TNNI3)外显子7进行基因扫描,聚合酶链反应(PCR)扩增目的片段,双脱氧末段终止法测序。对R145W突变患者进行家系调查,收集临床资料,分析其临床表型。结果在4个先证者家系9个HCM成员中发现cTnI-R145W突变,2/3的患者表现为心尖部肥厚,3/4先证者有猝死家族史,其中一例家族成员在随访期内心源性猝死。结论 cTnI-R145W突变可导致心尖部肥厚为主的HCM,其表型恶性程度较高。结合同一突变位点在西方人群中可以导致典型的限制型心肌病表型,提示R145W可以导致不同类型的心肌病。     

Prevalence and spectrum of mutations in the sarcomeric troponin T and I genes in a cohort of Spanish cardiac hypertrophy patients

We sequenced the coding exons of the cardiac troponins T (TNNT2) and I (TNNI3) genes in 115 Spanish HCM-patients (32% with a family history of the disease). Only two (2%) had mutations in the TNNT2 (Arg278>Cys and Arg92>Lys). These mutations were associated with variable clinical outcomes. No patient had TNNI3-mutation. We also genotyped these patients and 320 healthy controls for a 5 bp insertion/deletion (I/D) polymorphism in intron 3 of TNNT2. DD-homozygotes for the 5 bp I/D polymorphism were significantly more frequent among the patients (OR=1.83, 95% CI=2.10-5.16).     

酵母双杂交筛选与CVB3 VP3相互作用的人心脏蛋白

目的 从人心脏cDNA文库中筛选与B3型柯萨奇病毒(coxsackievirus group B type 3,CVB3)结构蛋白VP3相互作用的蛋白,为进一步研究CVB3分子致病机制提供新的线索。方法 构建酵母双杂交重组质粒(pGBKT7-VP3),转化至感受态酵母菌AH109,检测BD-cMyc-VP3融合蛋白自激活,应用酵母双杂交筛选与CVB3 VP3相互作用的人心脏蛋白。对阳性候选克隆进行测序和同源性比对分析;α-半乳糖苷酶活性定量分析VP3与各阳性蛋白之间相互作用的强弱。结果 诱饵质粒pGBKT7-VP3构建成功,检测到BD-cMyc-VP3融合蛋白在AH109中表达,且诱饵蛋白VP3在酵母中不存在自激活,从人心脏cDNA文库中筛选到10个与CVB3 VP3相互作用的蛋白:真核翻译起始因子4A2、羟酰辅酶A脱氢酶三官能蛋白转录变体3、肌钙蛋白I3型、平滑肌蛋白3、线粒体乙醛脱氢酶2等。结论 本研究成功应用酵母双杂交技术筛选出与CVB3 VP3相互作用的10个蛋白。为研究CVB3引起心肌炎和心肌疾病的分子致病机制提供了一些新的线索。     

Recapitulation of genome-wide association studies on body mass index in the Korean population

Obesity is a risk factor for multiple disorders such as diabetes and cardiovascular disease. Recently, a genome-wide association study for body mass index (BMI) was conducted in 249?796 individuals of European ancestry by the Genetic Investigation of Anthropometric Traits (GIANT) consortium. They identified 14 known obesity susceptibility loci and 18 new loci associated with BMI at the genome-wide significance level (P<5 × 10??). Because the prevalence and severity of obesity vary among ethnic groups, it is worthy to investigate these results in another ethnic population. We examined the BMI association of 19 single-nucleotide polymorphisms (SNPs) out of the 32 in 8842 individuals from the Korean Association Resource data, and found 12 SNPs to be associated with BMI in the Korean population. Eight loci, rs10968576 (BDNF), rs3817334 (MTCH2), rs1558902 (FTO), rs571312 (MC4R), rs543874 (SEC16B), rs987237 (TFAP2B), rs2867125 (TMEM18) and rs7138803 (FAIM2), were previously known obesity susceptibility loci, and the remaining four loci, rs1514175 (TNNI3K), rs206936 (NUDT3), rs4771122 (MTIF3) and rs2241423 (MAP2K5), were newly identified as BMI loci by the GIANT study. Further, all 12 SNPs showed the same direction of effect on BMI between the two ethnic groups, suggesting a similar genetic architecture governing the obesity.