钙调神经磷酸酶信号通路与心肌重构

心肌重构是心脏对缺氧或压力负荷过重的一种适应性反应。心肌细胞适应不良性肥大和心肌细胞坏死或凋亡是心肌重构的基础改变因素。已知细胞内钙超载与心肌重构有关 ,但对其作用机制还不清楚。最近研究表明 ,由Ca2 + 活化的钙调神经磷酸酶 (CaN)在心肌重构的信号传导中起重要作用 ,其可能是Ca2 + 信号导致肥大基因活化的偶联环节。同时 ,CaN通过影响其他信号通路对细胞凋亡有调节作用 ,但对其作用机制还不清楚。应用抑制CaN活性的药物CsA及FK5 0 6可以阻滞心肌肥大的发生发展 ,提示Ca2 + CaN依赖的信号传递通路可能是介导心肌重构的一条新的、重要的通路     

丹参酮Ⅱ A抑制血管紧张素Ⅱ诱导大鼠心肌肥大的机制

目的在原代培养的新生大鼠心肌细胞的基础上,观察丹参酮ⅡA磺酸钠盐(STS)对血管紧张素Ⅱ(AngⅡ)诱导的心肌细胞肥大的影响,以探讨STS在钙调神经磷酸酶(CaN)依赖的信号通路心肌肥大中的作用. 方法以培养的原代心肌细胞为模型,用AngⅡ刺激细胞外Ca2+内流,丹参酮ⅡA及钙离子拮抗剂维拉帕米(Ver)进行干预,检测心肌细胞[Ca2+]i及钙调神经磷酸酶(CaN)、丝裂素活化蛋白激酶(MAPK)和蛋白激酶C(PKC)活性;[3H]-亮氨酸掺入法测定心肌细胞蛋白质合成速率作为心肌细胞肥大的指标.结果AngⅡ刺激组[Ca2+]i水平及蛋白核酸合成速率明显增高,与对照组相比差异显著(P＜0.01),而STS能有效地降低由AngⅡ刺激引起的[Ca2+]i增高(P＜0.01 vs AngⅡ组),明显抑制AngⅡ诱导的蛋白质合成速率的增加(P＜0.01 vs AngⅡ组).AngⅡ刺激组CaN、PKC活性与对照组相比差异有显著性(P＜0.05、P＜0.01).STS及Ver抑制AngⅡ介导的心肌细胞CaN、PKC活性的增高.结论CaN通路在AngⅡ刺激的心肌细胞肥大中起重要作用;STS具有Ca2+阻滞剂的特点,能有效地降低由AngⅡ刺激引起的[Ca2+]i增高,导致CaN活性降低阻滞心肌肥大的发生和发展.     

钙调神经磷酸酶在醛固酮诱导心肌肥大中的作用

目的观察钙调神经磷酸酶(CaN)在醛固酮(Ald)诱导的心肌肥大信号转导机制中的作用及其调节。方法24只Wistar大鼠随机分为2组:实验组和对照组。实验组给予醛固酮腹腔注射后,再随机分为3组,分别给予环孢霉素A、螺内酯、及生理盐水干预,对照组仅腹腔注射生理盐水。测定大鼠血浆中血管活性因子Ald、AngⅡ、ET1与NO-3的浓度,心重/体重,心肌组织中的CaN活性;心肌组织中肥大相关基因心房利钠因子(ANF)及CaNAβmRNA的水平,同时用免疫组化方法观察心肌胞浆中CaN的表达。结果醛固酮腹腔注射后血浆中的醛固酮水平明显增高,醛固酮腹腔注射4周可使心肌肥大相关基因ANFmRNA水平明显升高,心肌中CaN活性明显升高,心肌细胞浆中的CaN表达上调;环孢霉素A及螺内酯干预4周,可明显抑制心肌CaN活性,并下调ANF(P<0.05)的表达。结论CaN参与了外源性醛固酮诱导的心肌肥大的信号通路,醛固酮通过活化CaN,使肥大相关基因表达增加产生心肌肥大。螺内酯通过拮抗醛固酮与受体结合抑制心肌肥大。     

钙调神经磷酸酶在醛固酮诱导心肌肥大中的作用

目的观察钙调神经磷酸酶(CaN)在醛固酮(Ald)诱导的心肌肥大信号转导机制中的作用及其调节.方法24只Wistar大鼠随机分为2组实验组和对照组.实验组给予醛固酮腹腔注射后,再随机分为3组,分别给予环孢霉素A、螺内酯、及生理盐水干预,对照组仅腹腔注射生理盐水.测定大鼠血浆中血管活性因子Ald、AngⅡ、ET-1与NO-3的浓度,心重/体重,心肌组织中的CaN活性;心肌组织中肥大相关基因心房利钠因子(ANF)及CaNAβ mRNA的水平,同时用免疫组化方法观察心肌胞浆中CaN的表达.结果醛固酮腹腔注射后血浆中的醛固酮水平明显增高,醛固酮腹腔注射4周可使心肌肥大相关基因ANF mRNA水平明显升高,心肌中CaN活性明显升高,心肌细胞浆中的CaN表达上调;环孢霉素A及螺内酯干预4周,可明显抑制心肌CaN活性,并下调ANF(P＜0.05)的表达.结论CaN参与了外源性醛固酮诱导的心肌肥大的信号通路,醛固酮通过活化CaN,使肥大相关基因表达增加产生心肌肥大.螺内酯通过拮抗醛固酮与受体结合抑制心肌肥大.     

钙调神经磷酸酶信号通路与心肌细胞肥大

目的　探讨不同来源的细胞内Ca2 ([Ca2 ]i)在钙调神经磷酸酶 (CaN) 活化T细胞核因子 3 (NFAT3 )介导的心肌肥大中的作用。方法　分别用血管紧张素Ⅱ (AngⅡ )或雷尼丁刺激培养的大鼠心肌细胞外Ca2 跨膜内流或细胞内Ca2 释放 ,检测CaN、NFAT3、锌指转录因子 (GATA4)蛋白量、NFAT3定位以及氚 亮氨酸 (3H Leu)掺入量 ,环孢素A作为CaN特异抑制剂。结果　AngⅡ、雷尼丁刺激 1、3d ,心肌细胞CaN、NFAT3、GATA4蛋白表达及3H Leu掺入量较对照组明显增高(P值 <0 0 5或 <0 0 1)。AngⅡ和雷尼丁刺激第 1天 ,心肌细胞NFAT3表达由胞质转入胞核表达为主。环孢素A可抑制上述作用 ,与刺激组相比差异有显著性 (P <0 0 5或 <0 0 1)。结论　刺激心肌细胞Ca2 内流及Ca2 释放 ,均可激活CaN NFAT3信号通路。CaN NFAT3信号通路的激活与[Ca2 ]i增加有关 ,而与 [Ca2 ]i的来源无关。环孢素A能够抑制AngⅡ和雷尼丁介导的CaN NFAT 3 GATA 4表达的增加和蛋白质合成     

螺内酯抗CaN依赖的肾性高血压大鼠心肌肥大的研究

目的观察螺内酯(Spironolactone,Spiro)抗钙调神经磷酸酶(calcineurin,CaN)依赖的肾性高血压大鼠心肌肥大的作用.方法20只Wistar大鼠随机分为3组两组采用一肾一夹模型制造肾性高血压,其中spiro组(n=7)给予螺内酯灌胃,op组(n=7)予水灌胃;假手术组(sham op n=6)只给予水灌胃.称重法测定心重比,发色底物法测CaN活性;同时用免疫组织化学染色方法,观察心肌中CaN及活化T细胞核因子(nuclear factor of activatedT cell,NFAT)的表达.结果肾性高血压大鼠经螺内酯灌胃4周,其心重比较未干预组明显降低(P＜0.05),心肌肥大受到抑制,同时发现心肌中CaN活性较未干预组显著下降,免疫组化显示螺内酯干预组心肌中CaN及NFAT表达降低.结论螺内酯抑制肾性高血压心肌肥大的机制与其下调心肌胞浆中CaN表达及其活性有关.     

钙调神经磷酸酶依赖的信号通路在致心肌肥大中的作用

心肌细胞内持续的Ca2+平台激活钙调神经磷酸酶(CaN),使活化T细胞核因子c(NF-ATc)去磷酸化并进入胞核.去磷酸化的NF-ATc再与锌指转录因子(GATA4)等相互作用,活化多种心肌肥厚的相关基因,导致心肌肥厚.免疫抑制剂环胞素A(CsA)、FK506等可抑制CaN活性,消除心肌肥厚而改善心衰.     

钙调神经磷酸酶依赖的信号通路在致心肌肥大中的作用

心肌细胞内持续的Ca2 平台激活钙调神经磷酸酶（CaN)，使活化T细胞核因子c(NF-ATc)去磷酸化并进入胞核，去磷酸化的NF－ATc再与锌指转录因子（GATA4）等相互作用，活化多种心肌肥厚的相关基因导致心肌肥厚，免疫抑制剂环胞素A（CsA),FK506等可抑制CaN活性，消除心肌肥厚而改善心衰。     

κ阿片受体激动通过钙调神经磷酸酶和胞外信号调节激酶信号抑制异丙肾上腺素诱导的乳鼠心肌肥大

目的探讨κ阿片受体(κ-OR)激动抑制异丙肾上腺素(Iso)诱导的乳鼠心肌细胞肥大的信号转导机制。方法利用体外培养模型,以Iso 10μmol/L诱导心肌细胞肥大,观察κ-OR激动剂U50488 H1μmol/L的作用,并进一步探索在钙调神经磷酸酶(CaN)特异性抑制剂环孢菌素A(CsA)、细胞外信号调节激酶(ERK)抑制剂U0126、L型钙通道阻滞剂维拉帕米及β肾上腺素受体阻断剂普萘洛尔存在的情况下,κ-OR的激活对心肌肥大的影响。Lowry法测心肌细胞蛋白含量;消化分离法及计算机图像分析系统测细胞体积;采用Till阳离子测定系统,以Fura-2/AM为荧光探针,观察胞内[Ca2+]i瞬间变化;Western blot法测CaN、ERK表达。结果U50488 H1μmol/L可以明显抑制Iso诱导的心肌蛋白含量增加、体积增大和胞内[Ca2+]i瞬间变化的增高,其抑制程度与CsA、U0126、维拉帕米及普萘洛尔相似;U50488 H可以抑制Iso诱导的CaN表达增加和ERK磷酸化增加;CaN抑制剂CsA可以抑制Iso诱导的ERK磷酸化增加,ERK抑制剂U0126可以抑制Iso诱导的CaN表达增加。结论κ-OR...     

CaN/NFAT3信号通路与心血管疾病研究进展

正钙调神经磷酸酶(CaN)-T细胞活化核因子(NFAT)3在心血管系统表达丰富,在心血管疾病发生发展中发挥重要作用[1],关于CaN/NFAT3信号通路在心肌损伤过程中作用机制的研究愈发明确。本文对CaN/NFAT3信号通路与心血管疾病研究进展进行综述。1CaNCaN是普遍存在的丝氨酸/苏氨酸磷酸化酶家族中一员,钙调神经磷酸酶全酶是一种异源二聚体,包含     

Calcium channel blocker and cardiac hypertrophy

Calcium channel blockers are commonly treated to the patients with hypertension. Epidemiological studies suggest that cardiac hypertrophy is an independent risk factor for cardiac morbidity and mortality from cardiovascular disease. Long-acting calcium channel blockers, but not short-acting calcium channel blockers had moderately beneficial and statistically indistinguishable effects on regression of LV hypertrophy. Japanese Society of Hypertension Guidelines for the Management of Hypertension (JSH 2004) recommended to treat A II receptor blockers, ACE inhibitors or calcium channel blockers against the hypertensive patients with cardiac hypertrophy. Further studies will be necessary to elucidate the detailed molecular mechanism how calcium channel blockers reduce cardiac hypertrophy.     

Risk Reduction Following Regression of Cardiac Hypertrophy

Cardiac hypertrophy in essential hypertension is documented to be an independent risk factor for congestive heart failure, coronary heart disease and cardiac sudden death. Reduction of left ventricular hypertrophy therefore emerged as a new challenge of antihypertensive treatment. Sympatholytic agents, calcium entry blockers, and angiotensin converting enzyme inhibitors have been found to reduce left ventricular hypertrophy, whereas vasodilators (and most likely also diuretics) are unable to reduce left ventricular mass despite good control of arterial hypertension. Several studies indicated that reduction of left ventricular hypertrophy is not detrimental to cardiac pump function: systolic and diastolic function were found to be maintained at rest and during exposure to increased pressure load. In hypertensive patients with left ventricular hypertrophy ventricular arrythmias have been reported to be increased and to be the pathophysiological link for the increased risk of cardiac sudden death. Reduction of cardiac hypertrophy was found to be accompanied by a reduction of prevalence and severity of ventricular arrhythmias if treated with betablockers, calcium entry blockers or converting enzyme inhibitors. Whether reduction of cardiac hypertrophy indeed decreases the cardiovascular risk attributed to left ventricular hypertrophy is unknown at present, although clinical studies support such a viewpoint.     

Signaling Pathways Involved in Cardiac Hypertrophy

Cardiac hypertrophy is the heart's response to a variety of extrinsic and intrinsic stimuli that impose increased biomechanical stress. Traditionally, it has been considered a beneficial mechanism; however, sustained hypertrophy has been associated with a significant increase in the risk of cardiovascular disease and mortality. Delineating intracellular signaling pathways involved in the different aspects of cardiac hypertrophy will permit future improvements in potential targets for therapeutic intervention. Generally, there are two types of cardiac hypertrophies, adaptive hypertrophy, including eutrophy (normal growth) and physiological hypertrophy (growth induced by physical conditioning), and maladaptive hypertrophy, including pathologic or reactive hypertrophy (growth induced by pathologic stimuli) and hypertrophic growth caused by genetic mutations affecting sarcomeric or cytoskeletal proteins. Accumulating observations from animal models and human patients have identified a number of intracellular signaling pathways that characterized as important transducers of the hypertrophic response, including calcineurin/nuclear factor of activated T- cells, phosphoinositide 3-kinases/Akt (PI3Ks/Akt) , G protein-coupled receptors, small G proteins, MAPK, PKCs, Gpl30/STAT3, Na /H exchanger, peroxisome proliferator-activated receptors, myocyte enhancer factor 2/histone deacetylases, and many others. Furthermore, recent evidence suggests that adaptive cardiac hypertrophy is regulated in large part by the growth hormone/insulin-like growth factors axis via signaling through the PI3K/Akt pathway. In contrast, pathological or reactive hypertrophy is triggered by autocrine and paracrine neurohormonal factors released during biomechanical stress that signal through the Gq/phosphorlipase C pathway, leading to an increase in cytosolic calcium and activation of PKC.     

Possible involvement of endothelin-1 in cardioprotective effects of benidipine.

Benidipine hydrochloride has been developed as an antagonist for the L-type calcium channel and is used as an anti-hypertensive drug. But recent studies have reported that benidipine exerts not only antihypertensive actions but also anti-hypertrophic actions on cardiac muscles. Endothelin-1 (ET-1), one of the endogenous pathological humoral factors of cardiovascular diseases such as hypertension and heart failure, has a strong vasoconstrictive action and could induce hypertension and cardiac hypertrophy. So, it is a matter of great interest whether or not calcium antagonists can decrease cardiac hypertrophy induced by the pathological vasoactive substances such as ET-1. Thus, the present study was designed to elucidate the effects of benidipine on cardiac hypertrophy, and particularly on the interaction with ET-1, using neonatal rat cardiac myocytes (MCs) and cardiac non-myocytes (NMCs) culture systems. Cells were cultured with or without ET-1, benidipine, and nifedipine and the effects of calcium antagonists on cardiac hypertrophy were evaluated by incorporations of [3H]-leucine and [3H]-thymidine into MCs and/or NMCs. Benidipine significantly decreased the ET-1-induced increase of [3H]-leucine and [3H]-thymidine uptake into cardiac MCs and NMCs, whereas no significant effects of nifedipine were observed. Furthermore, benidipine (10(-8)M) attenuated ET-1 secretions from NMCs. In summary, benidipine at least partially decreased the cardiac hypertrophy induced by paracrine mechanisms through its attenuation of ET-1 secretions from NMCs. Benidipine could thus be a useful tool for preventing cardiac hypertrophy due to hypertension.     

Urocortin-induced cardiomyocytes hypertrophy is associated with regulation of the GSK-3β pathway

Urocortin-1 (UCN), a member of the corticotropin-releasing factor, is a cardioprotective peptide, and is also involved in cardiac hypertrophy. The involvement of GSK-3β, a pivotal kinase in cardiac hypertrophy, in response to UCN is not yet documented. Cardiomyocytes from adult rats were stimulated for 48 h with UCN. Cell size, protein, and DNA contents were determined. Phosphorylated and total forms GSK-3β and the total amount of β-catenin were quantified by Western immunoblots. The effects of astressin, a UCN competitive receptor antagonist, were also evaluated. UCN increased cell size and the protein-to-DNA ratio, in accordance with a hypertrophic response. This effect was associated with increased phosphorylation of GSK-3β and marked accumulation of β-catenin, a downstream element to GSK-3β. All these effects were prevented by astressin and LY294002, an inhibitor of the phosphatidyl-inositol-3-kinase. UCN-induced cardiomyocytes hypertrophy is associated with regulation of GSK-3β, a pivotal kinase involved in cardiac hypertrophy, in a PI3K-dependent manner. Furthermore, the pharmacological blockade of UCN receptors was able to prevent UCN-induced hypertrophy, which leads to inhibition of the Akt/GSK-3β pathway.     

Calcium signals:regulatory mechanisms of cardiac gene expression and involvement in the development of cardiac hypertrophy

It is well-known that calcium plays an important role in excitation-contraction coupling in cardiac myocytes. Recently, an emerging body of evidence has demonstrated that calcium signals are critically involved in the development of cardiac hypertrophy and congestive heart failure. To establish a new strategy for prevention and treatment for cardiac hypertrophy, it will be required to decode the calcium signals involved in cardiac growth and function.     

Cardiomyocyte calcineurin signaling in subcellular domains: from the sarcolemma to the nucleus and beyond

The serine-threonine phosphatase calcineurin is activated in cardiac myocytes in the diseased heart and induces pathological hypertrophy. Calcineurin activity is mainly triggered by calcium/calmodulin binding but also through calpain mediated cleavage. How controlled calcineurin activation is possible in cardiac myocytes, which typically show a 10-fold difference in cytosolic calcium concentration with every heartbeat, has remained enigmatic. It is now emerging that calcineurin activation and signaling occur in subcellular microdomains, in which it is brought together with target proteins and exceedingly high concentrations of calcium in order to induce downstream signaling. We review current evidence of subcellular calcineurin mainly at the sarcolemma and the nucleus, but also in association with the sarcoplasmic reticulum and mitochondria. We also suggest that knowledge about subcellular signaling could help to develop inhibitors of calcineurin in specific microdomains to avoid side-effects that may arise from complete calcineurin inhibition.