Peters D G, Mitchell H L, McCune S A, Park S, Williams J H, Kandarian S C
Boston University, Department of Health Sciences, MA 02215, USA.
Circ Res. 1997 Nov;81(5):703-10. doi: 10.1161/01.res.81.5.703.
Congestive heart failure leads to skeletal muscle abnormalities, one of which is a prolongation of sarcoplasmic reticulum Ca2+ flux. The purpose of this study was to determine whether skeletal muscle of spontaneous hypertensive and heart failure rats have alterations in the expression of the sarcoplasmic (or endoplasmic) reticulum Ca(2+)-ATPase (SERCA) gene. Northern analysis revealed that SERCA1, the predominant skeletal muscle isoform, was decreased by 45%, 43%, and 58% in the tibialis anterior, plantaris, and diaphragm muscles, respectively. Ribonuclease protection assay showed that the decrease was due to the adult isoform, SERCA1a, with minor changes in the alternatively spliced neonatal isoform, SERCA1b. There was no change in SERCA1 mRNA levels in gastrocnemius muscles. No change was found in SERCA2a (cardiac/slow skeletal isoform) mRNA or protein levels or in SERCA2b (smooth muscle isoform), dihydropyridine receptor, or alpha-actin mRNA levels in diaphragm muscle. Northern blot and ribonuclease protection assays showed that SERCA2a decreased 61% in the heart while the alternatively spliced isoform, SERCA2b, decreased 27%. Western analysis of the tibialis anterior, diaphragm, and gastrocnemius muscles showed a decrease in SERCA1 protein levels by 46%, 64%, and 42%, respectively, whereas sarcoplasmic reticulum Ca(2+)-ATPase activity, a functional correlate of SERCA expression, was decreased by 38%, 38%, and 40% in the same muscles, SERCA2 protein expression decreased by 36% in the failing heart. Decreases in both mRNA and protein suggest pretranslational control of SERCA1 expression, whereas the lack of decreased SERCA1 mRNA in gastrocnemius muscle suggests translational regulation. The decreased SERCA1 protein expression in all muscles studied probably contributes to contractile abnormalities related to excitation-contraction coupling function in heart failure.
充血性心力衰竭会导致骨骼肌异常，其中之一是肌浆网Ca2+通量延长。本研究的目的是确定自发性高血压和心力衰竭大鼠的骨骼肌中肌浆网（或内质网）Ca(2+)-ATP酶（SERCA）基因的表达是否发生改变。Northern分析显示，主要的骨骼肌异构体SERCA1在胫前肌、跖肌和膈肌中分别降低了45%、43%和58%。核糖核酸酶保护试验表明，这种降低是由于成人异构体SERCA1a引起的，而选择性剪接的新生儿异构体SERCA1b变化较小。腓肠肌中SERCA1 mRNA水平没有变化。在膈肌中，SERCA2a（心脏/慢骨骼肌异构体）的mRNA或蛋白质水平、SERCA2b（平滑肌异构体）、二氢吡啶受体或α-肌动蛋白mRNA水平均未发现变化。Northern印迹和核糖核酸酶保护试验表明，SERCA2a在心脏中降低了61%，而选择性剪接的异构体SERCA2b降低了27%。对胫前肌、膈肌和腓肠肌的Western分析显示，SERCA1蛋白水平分别降低了46%、64%和42%，而肌浆网Ca(2+)-ATP酶活性（SERCA表达的功能相关指标）在相同肌肉中分别降低了38%、38%和40%，SERCA2蛋白表达在衰竭心脏中降低了36%。mRNA和蛋白质水平的降低表明SERCA1表达存在翻译前调控，而腓肠肌中SERCA1 mRNA未降低表明存在翻译调控。在所研究的所有肌肉中SERCA蛋白表达的降低可能导致了与心力衰竭中兴奋-收缩偶联功能相关的收缩异常。
