日本科学家最近发现发现了一种有利于心脏发育的蛋白质。该研究论文发表 6月4日发表于《自然》。 科学家通过针对蝌蚪的实验,发现在蝌蚪的心脏发育完成之後,移除蝌蚪体内 的IGFBP-4蛋白质，蝌蚪的心脏变得越来越小最後竟然消失了。 研究人员目前尚不清楚IGFBP-4蛋白质是否能在人体胚胎干细胞分化过程中起 到作用。但是实验表明IGFBP-4蛋白质在维护心脏健康发育方面能起到非常重 要的作用。 IGFBP-4蛋白质是由肝脏产生的。胎儿首先形成的是心脏,然後等生长到中期 阶段时,IGFBP-4蛋白质才开始起作用,它对心脏的发育很重要。心脏长成之後 ,如果IGFBP-4蛋白质被移除,心脏就会慢慢消失。蝌蚪实验证实了这一理论。 IGFBP-4 is an inhibitor of canonical Wnt signalling required for cardiogenesis nsulin-like growth-factor-binding proteins (IGFBPs) bind to and modulate the actions of insulin-like growth factors (IGFs)1. Although some of the actions of IGFBPs have been reported to be independent of IGFs, the precise mechanisms of IGF-independent actions of IGFBPs are largely unknown1, 2. Here we report a previously unknown function for IGFBP-4 as a cardiogenic growth factor. IGFBP-4 enhanced cardiomyocyte differentiation in vitro, and knockdown of Igfbp4 attenuated cardiomyogenesis both in vitro and in vivo. The cardiogenic effect of IGFBP-4 was independent of its IGF-binding activity but was mediated by the inhibitory effect on canonical Wnt signalling. IGFBP-4 physically interacted with a Wnt receptor, Frizzled 8 (Frz8), and a Wnt co-receptor, low-density lipoprotein receptor-related protein 6 (LRP6), and inhibited the binding of Wnt3A to Frz8 and LRP6. Although IGF-independent, the cardiogenic effect of IGFBP-4 was attenuated by IGFs through IGFBP-4 sequestration. IGFBP-4 is therefore an inhibitor of the canonical Wnt signalling required for cardiogenesis and provides a molecular link between IGF signalling and Wnt signalling. --

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