Farhadian F, Barrieux A, Lortet S, Marotte F, Oliviero P, Rappaport L, Samuel J L
Inserm Unité 127, IFR Circulation Lariboisière, Université D. Diderot Hôpital Lariboisière, Paris.
Lab Invest. 1994 Oct;71(4):552-9.
Fibronectin, an extracellular matrix protein, exists as multiple isoforms expressed in a time- and cell-dependent manner. Since the developmental pattern of fibronectin expression has not been determined in the heart, the first issue of this study was to investigate the expression of total fibronectin mRNA as well as its isoforms during cardiac ontogeny. In adults, pressure overload induces a shift towards the fetal form of proteins expressed by either muscle or nonmuscle cardiac cells. Fetal forms of fibronectin mRNA being found in smooth and nonmuscle cardiac cells soon after imposition of pressure overload, the pattern of fibronectin expression during the development of pathological growth was analyzed to determine whether the two conditions of cardiac growth resulted in an identical pattern of fibronectin expression.
Total RNA were isolated from rat heart (a) during in utero and postnatal life and (b) at varying periods of time after imposition of a pressure overload induced by coarctation of the thoracic aorta in 25-day-old rats. Fibronectin-EIIIA+ or -EIIIB+ and total fibronectin mRNAs were quantitated by reverse transcription-polymerase chain reactions and dot-blot analysis, respectively.
Fibronectin mRNA, abundant in the 14-day-old fetal heart, rapidly decreased during cardiac physiologic growth (> 5-fold); no changes in the fibronectin mRNA level was observed during the development of pressure-induced cardiac hypertrophy. The percentages of fibronectin transcripts containing EIIIA or EIIIB exons, very high in the early fetal heart (> 45%), harmoniously decreased during cardiac maturation (< 12%). Aortic coarctation resulted in an early, transient (12 to 48 hours) and preferential expression of fibronectin-EIIIA+ mRNA (approximately 40%).
In rat heart, neither physiologic nor pressure-induced growth requires increased amounts of fibronectin mRNA but the growth conditions specifically modulated the fibronectin pre-mRNA splicing.
纤连蛋白是一种细胞外基质蛋白，以多种同工型存在，其表达具有时间和细胞依赖性。由于尚未确定心脏中纤连蛋白表达的发育模式，本研究的首要问题是研究心脏个体发育过程中总纤连蛋白mRNA及其同工型的表达。在成体中，压力超负荷会导致心肌细胞或非心肌细胞表达的蛋白质向胎儿形式转变。压力超负荷后不久，在平滑肌和非心肌细胞中发现了胎儿形式的纤连蛋白mRNA，因此分析了病理性生长发育过程中纤连蛋白的表达模式，以确定两种心脏生长状况是否导致相同的纤连蛋白表达模式。
从大鼠心脏中分离总RNA，(a) 在子宫内和出生后，以及(b) 在25日龄大鼠胸主动脉缩窄诱导压力超负荷后的不同时间段。分别通过逆转录-聚合酶链反应和斑点印迹分析对纤连蛋白-EIIIA+或-EIIIB+以及总纤连蛋白mRNA进行定量。
纤连蛋白mRNA在14日龄胎儿心脏中丰富，在心脏生理生长过程中迅速下降（>5倍）；在压力诱导的心肌肥大发育过程中，未观察到纤连蛋白mRNA水平的变化。含有EIIIA或EIIIB外显子的纤连蛋白转录本百分比在胎儿早期心脏中非常高（>45%），在心脏成熟过程中协调下降（<12%）。主动脉缩窄导致纤连蛋白-EIIIA+ mRNA早期、短暂（12至48小时）且优先表达（约40%）。
在大鼠心脏中，生理性生长和压力诱导的生长均不需要增加纤连蛋白mRNA的量，但生长条件特异性地调节了纤连蛋白前体mRNA的剪接。
