Golubnitschaja O, Yeghiazaryan K, Skowasch D, Schild H, Bauriedel G
Department of Radiology, Rheinische Friedrich-Wilhelms-University of Bonn, Bonn, Germany.
Amino Acids. 2006 Oct;31(3):309-16. doi: 10.1007/s00726-006-0365-3. Epub 2006 Sep 5.
The mechanisms underlying aortic valve degeneration are largely unknown. Cardiac tissue responds to a variety of stimuli by hypertrophic growth. Molecular mechanisms resulting in the hypertrophic response indicate similarity and overlap with those involved in both cell growth and death. We hypothesized cell cycle control to be the key event in progression regulation of heart valve degeneration followed by tissue mineralization. Human post-operative tissue samples of native non-rheumatic stenosed aortic valves were categorized according to absence (group 1) or presence of calcification (group 2). The samples were ex vivo examined for cell density and presence of macrophage (CD68), as well as expression of two checkpoint genes, p21WAF1/CIP1 and 14-3-3 sigma, arresting the G1 and G2 cell cycle phases, respectively. Expression rates were measured by "Real-Time"-PCR on transcriptional level. Target protein expression was measured and their co-localization in different kinds of valvular cells was tested using immunohistochemical analysis. Whereas macrophages were localized predominantly in sub-endothelial layer of valvular fibrosis, p21WAF1/CIP1 and 14-3-3 sigma expression was observed also in the valvular spongiosa co-localized with alpha-actin positive cells. Significantly higher cell density and inflammation grade were observed in group 2 versus group 1. Accordingly, p21WAF1/CIP1 and 14-3-3 sigma expression was several fold higher in group 1 versus group 2 on both transcription and translation levels. The present findings on degenerated aortic valves show that increased cell density accompanied with consequent calcification might be attributed to the down-regulation of both G1 and G2 checkpoint genes.
主动脉瓣退变的潜在机制在很大程度上尚不清楚。心脏组织通过肥大性生长对多种刺激作出反应。导致肥大反应的分子机制表明与细胞生长和死亡所涉及的机制存在相似性和重叠。我们假设细胞周期控制是心脏瓣膜退变进展调节以及随后组织矿化过程中的关键事件。将人类非风湿性狭窄主动脉瓣的术后组织样本根据有无钙化分为两组（第1组无钙化，第2组有钙化）。对样本进行离体检查，检测细胞密度、巨噬细胞（CD68）的存在情况，以及分别阻滞G1期和G2期细胞周期的两个检查点基因p21WAF1/CIP1和14-3-3 sigma的表达。通过实时定量聚合酶链反应在转录水平测量表达率。测量靶蛋白表达，并使用免疫组织化学分析测试它们在不同类型瓣膜细胞中的共定位情况。巨噬细胞主要定位于瓣膜纤维化的内皮下层，而在瓣膜海绵体中也观察到p21WAF1/CIP1和14-3-3 sigma的表达，且与α-肌动蛋白阳性细胞共定位。与第1组相比，第2组观察到显著更高的细胞密度和炎症分级。相应地，在转录和翻译水平上，第1组中p21WAF1/CIP1和14-3-3 sigma的表达比第2组高几倍。关于退变主动脉瓣的当前研究结果表明，细胞密度增加以及随之而来的钙化可能归因于G1期和G2期检查点基因的下调。
