抑制鞘氨醇激酶-2活性加重血管紧张素II诱导的心肌细胞肥大

目的 本实验旨在明确鞘氨醇激酶（sphingosine kinase,SphK）2在血管紧张素（angiotensin,Ang）II诱导的心肌细胞肥大中的作用。方法 分离并体外培养SD乳鼠心肌细胞。给予AngII（10 μmol/L）处理24h诱导心肌细胞肥大。AngII刺激时分别给予溶媒或SphK2特异性抑制剂ABC294640（1 μmol/L）共处理。采用蛋白免疫印迹法检测心肌细胞SphK2蛋白表达。采用酶联免疫吸附试验（enzyme-linked immunosorbant assay,ELISA）检测心肌细胞细胞核1-磷酸鞘氨醇（sphingosine 1-phosphate,S1P）水平。采用结晶紫染色观察AngII诱导的心肌细胞肥大程度。采用实时定量聚合酶链式反应（real time-polymerase chain reaction,RT-PCR）检测心肌细胞肥大标志基因心房钠尿肽（atrial natriuretic peptide,ANP）、脑钠尿肽（brain natriuretic peptide,BNP）和β-肌球蛋白重链（β-myosin heavy chain,β-MHC）mRNA表达水平。结果 与对照组比较,AngII处理上调心肌细胞SphK2蛋白表达和S1P浓度（均P<0.05）,并增加心肌细胞横截面积与ANP、BNP和β-MHC mRNA表达水平（均P<0.05）。与溶媒组比较,ABC294640处理显著降低了心肌细胞核S1P浓度,并进一步增加了AngII处理后的心肌细胞横截面积和肥大标志基因mRNA表达水平（均P<0.05）。结论 抑制SphK2活性加重AngII诱导的心肌细胞肥大。SphK2有可能成为治疗病理性心肌肥大的新靶点。     

微小RNA-155调节钙调磷酸酶和活化T细胞核因子4表达对心肌细胞肥大的影响

目的研究微小(microRNA,miR)-155对心肌细胞肥大的影响及对钙调磷酸酶(CaN-β)和活化T细胞核因子4(NFAT-4)表达的调控作用。方法培养大鼠心肌细胞H9C2(2-1),血管紧张素(Ang)Ⅱ诱导心肌细胞肥大,脂质体转染法将miR-155模拟物和miR-155抑制物转染入心肌细胞。分为对照组、AngⅡ组、mimics组、inhibitors组、AngⅡ+mimics组和AngⅡ+inhibitors组。实时荧光定量PCR检测心肌细胞miR-155的表达。逆转录PCR法检测心房钠尿肽(ANP)、β-肌球蛋白重链(β-MHC)和CaN-βmRNA表达水平。Western blot法检测CaN-β和NFAT-4蛋白表达水平。结果与AngⅡ组比较,AngⅡ+mimics组ANP、β-MHC、心肌细胞表面积、CaN-βmRNA和蛋白表达及NFAT-4蛋白表达明显降低,差异有统计学意义(P<0.05)。结论 CaN-β可能为miR-155的作用靶点,miR-155可通过负性调控CaN-β和NFAT-4的表达,减少心肌细胞ANP和β-MHC表达,抑制心肌细胞肥大。     

4,4′-二异硫氰基芪-2,2′-二磺酸对血管紧张素Ⅱ诱导心肌细胞肥大的作用

目的探讨氯通道阻滞剂4,4′-二异硫氰基芪-2,2′-二磺酸(DIDS)对血管紧张素Ⅱ(AngⅡ)诱导H9C2心肌细胞肥大的作用及其可能机制。方法应用AngⅡ1μmol/L刺激心肌H9C2细胞株,构建心肌细胞肥大模型,观察12、24、36、48和72h各项表达,另给予50、100、200μmol/L DIDS预处理H9C2细胞,细胞分组:空白组、AngⅡ组、DIDS组、AngⅡ+DIDS组;免疫荧光染色测量细胞表面积,BCA法检测蛋白含量,实时定量PCR法检测心肌肥厚基因心房钠尿肽(ANP)和肌球蛋白重链(β-MHC)mRNA表达,二氯荧光素二乙酸检测活性氧水平。结果48h细胞表面积最大(50 166±2697)μm2和总蛋白含量最大(1.68±0.06)mg/107个,36hANP mRNA为4.08±0.38和β-MHC mRNA为2.80±0.18,表达量均最高。与空白对照组比较,AngⅡ组心肌细胞表面积、总蛋白含量、ANP、β-MHC mRNA表达量和细胞内活性氧水平明显增加(P0.05),DIDS组无显著差异(P0.05);与AngⅡ组比较,DIDS+AngⅡ组的心肌细胞表面积明显减小(P0.05)、总蛋白含量明显减少(P0.05)、ANP mRNA和β-MHC mRNA表达量明显减低(P0.05)、细胞内活性氧水平明显下降(P0.05)。结论 DIDS可以有效抑制AngⅡ诱导的H9C2心肌细胞肥大,其机制可能与降低活性氧的水平有关。     

SK-7041对血管紧张素Ⅱ致大鼠心肌细胞肥大的干预作用

目的探讨SK-7041在血管紧张素Ⅱ(AngⅡ)致心肌细胞肥大过程中的抑制作用。方法常规方法培养大鼠原代心肌细胞,分为3组:对照组、肥大组、SK-7041组。利用AngⅡ刺激心肌细胞造成肥大模型,并给予SK-7041进行干预。反转录聚合酶链反应观察β-肌球蛋白重链(β-MHC)mRNA表达;相差显微镜和电镜观察心肌细胞的表面积和超微结构变化;免疫组织化学法检测c-fos蛋白的表达。结果大鼠原代心肌细胞在AngⅡ作用下表面积增加,超微结构发生改变;β-MHC mRNA和c-fos蛋白表达增加(P<0.05)。给予SK-7041干预后,上述变化显著缓解(P<0.05)。结论 SK-7041可抑制AngⅡ刺激引起的心肌细胞肥大,为临床上治疗心肌肥厚提供一条新的思路。     

PDE5抑制剂对异丙肾上腺素诱导乳鼠心肌细胞肥大的作用

目的 探讨磷酸二酯酶5（PDE5）抑制剂对异丙肾上腺素（Iso）所致的乳鼠心肌细胞肥大的保护作用。 方法 分离大鼠乳鼠心肌细胞,分为对照（Con）组,Iso组及异丙肾上腺素+西地那非（Iso+Sil）组,通过检测各组细胞活力及乳酸脱氢酶（LDH）含量,确定Sil的后续实验浓度,通过RT-PCR检测心肌肥大指标心房钠尿肽(ANP)和β-肌球蛋白重链(β-MHC) mRNA含量、流式细胞计数检测凋亡情况及Western blot检测内质网应激相关蛋白葡萄糖调节蛋白78（GRP78）和CCAAT增强子结合蛋白同源蛋白（CHOP）水平。 结果 与Con组相比,Iso组细胞活力降低（P<0.01）,LDH的释放增加（P<0.05）。与Iso组相比,一定浓度Sil预处理可以提高细胞活力及减少LDH的释放（P<0.05）,在5 μmol/L Sil预处理时达到最大效应。与Con组相比,Iso组增加ANP和β-MHC mRNA的表达、上调凋亡比率以及增加GRP78和CHOP的蛋白水平。与Iso组相比,Sil预处理可以降低ANP和β-MHC mRNA的表达,下调凋亡比率以及抑制GRP78和CHOP的蛋白表达。 结论 PDE5抑制剂Sil可以有效抑制Iso诱导的乳鼠心肌细胞肥大,其机制可能与凋亡和内质网应激的下调有关。     

组蛋白脱乙酰基酶抑制剂曲古霉素对心肌细胞肥大的影响

目的利用体外培养的大鼠乳鼠心肌细胞,研究曲古霉素(TSA)对血管紧张素II(Ang II)诱导的心肌细胞肥大的影响,并探讨相关机制。方法分离乳鼠心肌细胞进行原代培养,应用血管紧张素Ⅱ制备心肌细胞肥大模型。分别给予不同浓度的TSA预处理心肌细胞,观察TSA对心肌细胞面积、3H亮氨酸掺入率、心房利钠肽(ANP)、脑利钠肽(BNP)的mRNA表达水平的影响。同时通过检测乙酰化组蛋白3的蛋白表达水平,观察AngⅡ和TSA对组蛋白脱乙酰基酶(HDAC)活性的影响。应用Western blot检测AngⅡ和TSA处理后磷酸化的c-Jun氨基末端激酶(JNK)表达水平的变化。结果10-6mmol/L AngⅡ作用48 h后,心肌细胞面积增加至对照组的(1.63±0.46)倍(P<0.01),而10-7mmol/L和3×10-7mmol/L TSA预处理可以剂量依赖性的抑制AngⅡ引起的心肌细胞面积增大。TSA干预也阻断了AngⅡ引起的蛋白合成速率增加以及ANP和BNP的蛋白表达水平的增加(均为P<0.05)。AngⅡ刺激心肌细胞使乙酰化组蛋白3的蛋白表达水平降低,TSA可逆转这一效应。同时TSA抑制了AngⅡ介导的磷酸化JNK表达水平的升高。结论 TSA可显著抑制AngⅡ诱导的心肌细胞肥大和HDAC活性增加,可能通过抑制JNK的激活而发挥抑制心室肥厚的作用。     

泛素蛋白酶体抑制剂抑制钙调神经磷酸酶依赖的心肌细胞肥大

目的 研究泛素蛋白酶体抑制剂MG262对钙调神经磷酸酶信号通路的影响,探讨其抑制心肌细胞肥大的机制。方法 在去甲肾上腺素诱导培养的乳鼠肥大心肌细胞中加入MG262,通过Phalloidin染色观察细胞的形态,RNA Dot Blot检测胚胎蛋白基因表达,Western blot检测细胞中钙调神经磷酸酶蛋白含量,免疫荧光标记观察活化T细胞核因子c4（NFATc4）蛋白在细胞内分布。结果 去甲肾上腺素使细胞面积增大近1.1倍,胚胎基因心房利钠因子（ANF）、脑钠肽（BNP）、β肌球蛋白重链（β-MHC）的mRNA表达上调,细胞核内NFATc4蛋白表达水平增加。MG262明显抑制去甲肾上腺素诱导的细胞肥大（P<0.05）和ANP、BNP、β-MHC的mRNA表达上调（P<0.05）,细胞面积下降了33%;同时MG262使去甲肾上腺素诱导的细胞钙调神经磷酸酶蛋白表达水平下降,抑制NFATc4核内转位。结论 MG262可能通过抑制钙调神经磷酸酶信号通路,减轻心肌细胞肥大。     

DJ-1蛋白在去氧肾上腺素诱导的心肌细胞肥厚中的作用

目的 探讨DJ-1对去氧肾上腺素（phenylephrine,PE）诱导的心肌细胞肥厚的调控作用.方法 应用PE诱导乳鼠导致心肌细胞肥厚;通过Western blot观察心肌细胞DJ-1在PE刺激下的表达量改变;通过腺病毒载体过表达DJ-1,检测过表达效率;荧光定量聚合酶链反应（polymerase chain reaction,PCR）检测心肌肥厚标志物心房利钠肽（atrial natriuretic peptide,ANP）和B型利钠肽（B type-natriuretic peptide,BNP） mRNA表达水平改变;显微镜观察心肌细胞面积改变.结果 在PE诱导的心肌细胞肥厚过程中,DJ-1表达水平下调;PE可诱导ANP和BNP表达水平升高,心肌细胞面积增加;过表达DJ-1则显著抑制ANP和BNP的上调,减少心肌细胞面积的增大.结论 DJ-1可抑制PE诱导的心肌细胞肥厚.     

miR-499a-5p靶向调控CDKN1A基因在心肌细胞肥大中的作用机制研究

目的:探讨miR-499a-5p靶向细胞周期蛋白依赖性激酶抑制剂1A(CDKN1A)抑制血管紧张素Ⅱ(AngⅡ)诱导的心肌细胞肥大的作用机制。方法:体外培养大鼠心肌细胞H9c2,并将H9c2细胞随机分为正常对照(Con)组、细胞肥大模型(AngⅡ)组、转染对照(AngⅡ+miR-NC)组和转染(AngⅡ+miR-499a-5p)组。采用Image J软件测量单细胞表面积,实时荧光定量聚合酶链式反应(qRT-PCR)分析各组细胞中miR-499a-5p的表达水平,细胞计数试剂盒(CCK-8)检测细胞活性,流式细胞术检测细胞凋亡率,蛋白免疫印迹法(Western Blot)检测CDKN1A、cleaved Caspase-3以及心肌肥大标志蛋白心钠肽(ANP)、脑钠肽(BNP)和β-肌球蛋白重链(β-MHC)的表达水平,双荧光素酶报告基因实验验证miR-499a-5p和CDKN1A的靶向作用关系。结果:与Con组比较,AngⅡ组H9c2细胞表面积、凋亡率、CDKN1A、Cleaved Caspase-3、ANP、BNP和β-MHC蛋白表达水平明显升高(P<0.05),而细胞活力和mi...     

TGF-β_1及Ang Ⅱ对大鼠心肌细胞肥大的信号转导通路作用研究

目的:探讨在TGF-β1及AngⅡ分别诱导的大鼠心肌细胞肥大中Smad信号途径中Smad2蛋白的表达。方法:分别建立TGF-β1及AngⅡ诱导的大鼠心肌细胞肥大模型,分为正常对照组、TGF-β1组以及AngⅡ组。以碘化丙啶(PI)染色标记法检测心肌细胞中RNA的表达量以间接反映心肌细胞肥大。以实时荧光定量PCR检测心肌细胞肥大相关肌球蛋白重链β亚型(β-MHC)的表达。以Western blot检测心肌细胞中磷酸化Smad2信号蛋白的表达。结果:TGF-β1及AngⅡ诱导的培养心肌细胞中肥大相关蛋白β-MHC的表达均明显高于对照组(P0.01)。PI染色检测表明,TGF-β1组及AngⅡ组PI的含量明显增高(P0.01)。与对照组相比,TGF-β1及AngⅡ均可明显上调磷酸化Smadz(p-Smad2)的表达(P0.01)。TGF-β1组与AngⅡ组p-Smad2表达峰值相比无明显差异,但达峰的时间有所不同。结论:TGF-β1及AngⅡ单独均可诱导心肌细胞肥大,在此过程中p-Smad2蛋白的表达明显增加,TGF-β1与AngⅡ促进p-Smad2蛋白表达作用无明显差异。     

Tunicamycin aggravates endoplasmic reticulum stress and airway inflammation via PERK-ATF4-CHOP signaling in a murine model of neutrophilic asthma

Introduction: Endoplasmic reticulum (ER) stress has been considered to be an important regulator of airway inflammation in the pathogenesis of bronchial asthma, but the mechanism of ER stress involved in neutrophilic asthma remain not fully understood. Methods: Tunicamycin is a mixture of homologous nucleoside antibiotics, which is used to induce ER stress. In the present study, Tunicamycin was administered to mouse bronchial epithelial cells and a neutrophilic asthma model (OVA_LPS-OVA mice), and ER stress indicators and inflammatory cytokines were measured by Western blotting and Elisa. Results: Tunicamycin not only induced ER stress in mouse bronchial epithelial cells, but also increased expression of inflammation indicators such as IL-6, IL-8, and TNF-α via PERK-ATF4-CHOP signaling. Additionally, the phosphorylation of PERK and the expression levels of ATF4 and CHOP proteins and inflammatory cytokines (IL-6, IL-8 and TNF-α) were elevated in the lung tissue of OVA_LPS-OVA mice. Administering tunicamycin further increased protein expression levels of ER stress indicators and inflammatory cytokines, and resulted in more severe asthma phenotypes in OVA_LPS-OVA mice, suggesting that PERK-ATF4-CHOP signaling is associated with airway inflammation in neutrophil-dominant asthma. Conclusions: These data support the emerging notion that regulation of ER stress could be strongly associated with the development of neutrophilic asthma.     

阿替洛尔对小鼠心肌肥厚干预作用的研究

目的:观察β1受体阻滞剂阿替洛尔(atenolol,ATE)对主动脉弓缩窄术(aortic arches constriction,AAC)诱导的C57BL小鼠心肌肥厚模型的治疗作用。方法:通过AAC建立心肌肥厚小鼠模型,将24只雄性C57BL小鼠随机分为正常对照组、假手术(Sham)组、AAC组和AAT+ATE组,每组6只小鼠(n=6)。给予ATE 4周后,进行心脏超声检查,并测量心脏质量/体质量(HW/BW)、左心室质量/体质量(LVW/BW)、左室舒张末期内径(LVEDD)、左室收缩末期内径(LVEDS)、左室射血分数[LVEF(%)]和短轴缩短率[FS(%)]。应用PCR检测心肌组织中心房钠尿肽(ANP)、脑尿钠肽(BNP)和肌球蛋白重链(α-MHC)基因表达的水平,并行病理学检查。结果:与AAC组比较,正常对照组、Sham组和AAC+ATE组的LVEDD分别降低24.9%、17.7%和18.2%,LVEDS分别降低32.9%、34.1%和26.3%;LVEF(%)分别提高65.6%、75.8%和49.5%,FS(%)分别提高79.7%、100.0%和62.6%(均P<0.05);AAC+ATE组与AAC组相比,LVM/BW和心肌细胞平均横截面积均明显降低(P<0.01);而与正常对照组相比,细胞平均面积明显增大(P<0.05)。AAC+ATE组中ANP、BNP和α-MHC的表达水平显著低于AAC组(P<0.05)。结论:通过阻断β1受体ATE,可以对压力超负荷等原因诱导的心肌肥厚发挥治疗作用。     

5-氮胞苷对大鼠骨髓基质细胞心钠素及β-肌球蛋白重链表达的影响

目的 观察5-氮胞苷(5-AZ)诱导后体外培养骨髓基质细胞(BMSCs)心钠素(ANP)、β肌球蛋白重链(β-MHC)表达的变化.方法 分离培养SD大鼠BMSCs及新生乳鼠心室肌细胞.BMSCs的诱导分化采用第8代BMSCs,于传代后第3 d分为4组:正常对照组、上清液组、5-AZ组、5-AZ+上清液组.反转录聚合酶链反应法测定心肌特异性蛋白ANP、β-MHC基因表达水平的变化.结果 正常培养及心肌细胞上清培养液诱导的BMSCs不表达心肌特异性ANP、β-MHC;5-AZ诱导后的BMSCs表达ANP、β-MHC,分别31.5±5.6、32.1±8.3和33.7±5.6、46.6±8.3.心肌细胞上清培养液增加5-AZ诱导的BMSCs中β-MHC的表达水平,而对ANP表达无影响.结论 体外培养大鼠成体BMSCs在5-AZ诱导下可表达心肌特异性ANP、β-MHC.心肌细胞上清培养液可增加β-MHC表达水平.     

Antioxidant actions contribute to the antihypertrophic effects of atrial natriuretic peptide in neonatal rat cardiomyocytes

OBJECTIVE: Reactive oxygen species (ROS) such as superoxide have been linked to the hypertrophic response of the heart to stimuli including angiotensin II (AngII), mechanical stretch, and pressure overload. We have previously demonstrated that cGMP and protein kinase G mediate the antihypertrophic actions of the natriuretic peptides in rat cardiomyocytes and isolated whole hearts. The impact of natriuretic peptides on cardiac ROS generation, however, has not been investigated. We tested the hypothesis that reduced superoxide accumulation contributes to the antihypertrophic action of atrial natriuretic peptide (ANP). METHODS: Neonatal rat cardiomyocytes were cultured in serum-free medium with and without AngII (1 micromol/L) or endothelin-1 (ET(1), 60 nmol/L) in the presence and absence of ANP (1 micromol/L) or tempol (100 micromol/L). Hypertrophic responses, cardiomyocyte superoxide generation, and cardiomyocyte expression of NADPH oxidase were determined. RESULTS: AngII induced increases in cardiomyocyte size (to 176 +/- 9% n = 8 p < 0.001, at 48 h), beta-myosin heavy chain expression (to 4.0 +/- 1.6-fold n = 6 p < 0.05, at 48 h), c-fos expression (to 1.9 +/- 0.5-fold n = 7 p < 0.01, at 6 h), superoxide generation (to 181+/-21% n = 8 p < 0.005, at 24 h), and expression of the gp91phox subunit of NADPH oxidase (to 2.4 +/- 0.5-fold n = 7 p < 0.05, at 48 h). These effects were all significantly inhibited by ANP: cardiomyocyte size, beta-myosin heavy chain expression, c-fos expression, superoxide generation and gp91phox expression were reduced to 107 +/- 5% (n = 5 p < 0.05), 1.2 +/- 0.2-fold (n = 6 p < 0.05), 0.9 +/- 0.2-fold (n = 7 p < 0.05), 141 +/- 21% (n = 8 p < 0.05), and to 1.0 +/- 0.5-fold (n = 7 p < 0.05), respectively. These effects were mimicked by tempol. ANP and tempol also significantly inhibited ET1-induced increases in cardiomyocyte size and superoxide generation, but had no effect on markers of hypertrophy when studied alone. CONCLUSION: This data indicates that the antihypertrophic actions of ANP are accompanied by reduced levels of superoxide, suggesting an antioxidant action contributes to the antihypertrophic actions of ANP.     

Antihypertrophic actions of the natriuretic peptides in adult rat cardiomyocytes: importance of cyclic GMP

Atrial natriuretic peptide (ANP) prevents hypertrophy of neonatal cardiomyocytes. However, whether this effect is retained in the adult phenotype or if other members of the natriuretic peptide family exhibit similar antihypertrophic properties, has not been elucidated. OBJECTIVE: Our objective was to examine whether the natriuretic peptides protect against adult cardiomyocyte hypertrophy in vitro. METHODS: Adult rat cardiomyocytes were incubated with angiotensin II (Ang II)+/-ANP, B-type (BNP) or C-type (CNP) natriuretic peptides for determination of [3H]phenylalanine incorporation, c-fos mRNA expression and cyclic GMP. The effects of 8-bromo-cyclic GMP (cyclic GMP analogue), HS-142-1 (particulate guanylyl cyclase inhibitor) and KT5823 (cyclic GMP-dependent protein kinase inhibitor) were also investigated. RESULTS: Ang II-stimulated increases in markers of hypertrophy, [3H]phenylalanine incorporation (to 136+/-3% of control, n=9) and c-fos mRNA expression (4.3+/-1.4-fold, n=5), were completely prevented by each of ANP, BNP or CNP. This protective action was accompanied by increased cardiomyocyte cyclic GMP. Inhibitory actions on [3H]phenylalanine incorporation were mimicked by 8-bromo-cyclic GMP, and were abolished by HS-142-1. KT5823 blocked the response to BNP and CNP, but not to ANP. CONCLUSION: ANP prevents hypertrophy of adult rat cardiomyocytes. This protective action is shared by BNP and CNP and involves activation of particulate guanylyl cyclase receptors. Antihypertrophic effects of BNP and CNP are mediated through cyclic GMP-dependent protein kinase, but ANP can activate additional pathways independent of cyclic GMP to prevent adult cardiomyocte hypertrophy. These novel findings are of interest particularly since BNP appears to exert antifibrotic rather than antihypertrophic actions in vivo, while CNP is thought to act at least in part via the endothelium.