Saygili Erol, Rana Obaida R, Meyer Christian, Gemein Christopher, Andrzejewski Michael G, Ludwig Andreas, Weber Christian, Schotten Ulrich, Krüttgen Alexander, Weis Joachim, Schwinger Robert H G, Mischke Karl, Rassaf Tienush, Kelm Malte, Schauerte Patrick
Dept. of Cardiology, Medical Clinic I, University Hospital Rheinisch Westfälische Technische Hochschule Aachen, Pauwelsstrasse 30, 52074, Aachen, Germany.
Basic Res Cardiol. 2009 Jul;104(4):435-48. doi: 10.1007/s00395-008-0772-6. Epub 2009 Jan 15.
During atrial fibrillation, arterial hypertension and systolic or diastolic heart failure, atrial myocytes are exposed to increased baseline stretch. Atrial stretch has been shown to induce cellular hypertrophy and extracellular matrix remodeling (ECM) via angiotensin-II dependent pathways and the matrix metalloproteinases system (MMPs). We hypothesized that atrial myocytes exposed to static stretch may increase their ECM remodeling activity via up-regulation of MMP-2/-9. We then tested the hypothesis that the membrane bound angiotensin-II type 1 (AT1) receptor and the intracellular calcineurin (Cn)-NFAT signaling pathway are potential mediators of stretch-induced MMP alterations, since Cn-NFAT is one important contributor to myocyte hypertrophy.
Neonatal rat atrial myocytes (NRAM) were cultured under conditions of static stretch by 21%. The differential effects of selective AT1 receptor blockade by losartan, Cn blockade by Cyclosporine-A (CsA) or NFAT inhibition by 11R-VIVIT (VIV), were analyzed. Stretch resulted in a significant up-regulation of active-MMP-2/-9 protein amount (active-MMP-2 ng/microg: control 8.95 +/- 0.64 vs. stretch 13.11 +/- 0.74 / active-MMP-9 ng/microg: control 1.45 +/- 0.18 vs. stretch 1.94 +/- 0.21, all n = 5) and enzyme activity (MMP-2 in %: control 1 +/- 0.0 vs. stretch 1.87 +/- 0.25, n = 7) associated with a significant increase of the membrane-type-1-MMP (MT1-MMP) protein expression (MT1-MMP in %: control 1 +/- 0.0 vs. stretch 2.17 +/- 0.21, n = 8). These observations were accompanied by an activation of the Cn-NFAT pathway (Cn-activity in nmol PO(4) release/20 microg protein/30 min: control 0.37 +/- 0.08 vs. stretch 0.65 +/- 0.09, n = 3 / NFATc1-DNA binding activity in %: control 1 +/- 0.0 vs. stretch 1.53 +/- 0.17, n = 3). Losartan, CsA or VIV abolished stretch-induced alterations in MMP-2/-9 and MT1-MMP expression and enzyme activity by normalizing the Cn-activity and the DNA binding activity of NFATc1.
Our results present new insights in molecular mechanisms of ECM remodeling activity of atrial myocytes exposed to static stretch. The AT1-Cn-NFAT pathway is a potential mediator of MMP activation.
在心房颤动、动脉高血压以及收缩期或舒张期心力衰竭期间，心房肌细胞会受到更高的基础牵张。业已表明，心房牵张可通过血管紧张素-II依赖性途径和基质金属蛋白酶系统（MMPs）诱导细胞肥大和细胞外基质重塑（ECM）。我们推测，暴露于静态牵张的心房肌细胞可能通过上调MMP-2/-9来增强其ECM重塑活性。鉴于钙调神经磷酸酶（Cn）-活化T细胞核因子（NFAT）信号通路是导致心肌细胞肥大的一个重要因素，我们随后检验了以下假设，即膜结合血管紧张素-II 1型（AT1）受体以及细胞内Cn-NFAT信号通路是牵张诱导的MMP改变的潜在介质。
将新生大鼠心房肌细胞（NRAM）置于21%静态牵张条件下培养。分析了氯沙坦选择性阻断AT1受体、环孢素A（CsA）阻断Cn或11R-VIVIT（VIV）抑制NFAT的不同作用。牵张导致活性MMP-2/-9蛋白量显著上调（活性MMP-2 ng/μg：对照8.95±0.64 vs. 牵张13.11±0.74 / 活性MMP-9 ng/μg：对照1.45±0.18 vs. 牵张1.94±0.21，均n = 5）以及酶活性（MMP-2百分比：对照1±0.0 vs. 牵张1.87±0.25，n = 7），同时膜型1-MMP（MT1-MMP）蛋白表达显著增加（MT1-MMP百分比：对照1±0.0 vs. 牵张2.17±0.21，n = 8）。这些观察结果伴随着Cn-NFAT途径的激活（Cn活性，nmol PO(4)释放/20μg蛋白/30分钟：对照0.37±0.08 vs. 牵张0.65±0.09，n = 3 / NFATc1-DNA结合活性百分比：对照1±0.0 vs. 牵张1.53±0.17，n = 3）。氯沙坦、CsA或VIV通过使Cn活性和NFATc1的DNA结合活性正常化，消除了牵张诱导的MMP-2/-9和MT1-MMP表达及酶活性的改变。
我们的结果为暴露于静态牵张的心房肌细胞ECM重塑活性的分子机制提供了新的见解。AT1-Cn-NFAT途径是MMP激活的潜在介质。
