Nkx2—5基因与心脏发育

心脏发育是一个极其复杂的过程，它涉及胚胎发育过程中不同时间、不同空间的若干基因的先后表达。大量研究表明Ｎｋｘ２－５／Ｃｓｘ基因作为与发育密切相关的同源盒基因（ｈｏｍｅｏｂｏｘｇｅｎｅ）的一种，在心脏发育过程中起重要作用。本文根据已发表的文献资料，系统地阐述Ｎｋｘ２－５基因的结构、表达及其在心脏的调节功能与途径，进而在分子水平上对心脏的发生和发病有更深入的了解。     

Over-expression of Nkx2.5 and/or cardiac α-actin inhibit the contraction ability of ADSCs-derived cardiomyocytes

Adipose tissue-derived stromal cells (ADSCs) can differentiate into cardiomyocytes, which provide a source of new cardiomyocyte progenitors for tissue engineering. Here, we showed that ADSCs isolated from subcutaneous adipose tissues of mouse were largely negative for CD31, CD34, but positive for CD105. About 1.62% cells in these cells can spontaneously differentiate into cardiac-like cells (cells expressing cardiac marker proteins) when cultured in Dulbecco’s modified Eagle’s medium (DMEM) supplemented only with penicillin, streptomycin, and 20% newborn bovine serum (NBS), expressed cardiac markers such as MF20, Connexin45, cMHC, cTnT, a-actin, Nkx2.5, and GATA4, and part of these cells (account for about 0.47% of inoculated cells) showed spontaneous contractions accompanied by transient Ca²⁺ activity in culture. In vitro, although over-expression of Nkx2.5 and/or cardiac α-actin increased the number of cardiac-like cells expressing cardiac-specific proteins, but while inhibited the contraction function of ADSCs-derived cardiomyocytes.     

间充质干细胞分化为心肌细胞过程中细胞形态变化与Nkx2.5表达相关性的初步研究

体外BMSCs分化为心肌细胞过程中,细胞在形态及相关基因的表达上发生明显的变化。本研究以心肌组织裂解液诱导BMSCs,观察分化过程中细胞形态变化,根据心肌细胞发生过程中细胞形态变化规律,选定5个检测点,行PCR检测细胞中Nkx2.5的表达,以探究分化过程中细胞形态变化与相关基因表达规律及其之间的相关性。实验结果表明BMSCs分化为心肌细胞的过程中,细胞形态变化呈现明显规律:由单个大核,胞浆饱满,折光性好的纺锤形;逐渐演变为短杆状;形成突起并连接成网状结构;细胞端相接呈"竹节样"改变;最后形成肌管样结构;诱导前细胞不表达Nkx2.5,诱导过程中随着细胞形态的不断变化Nkx2.5持续表达并逐渐增强。说明间充质干细胞分化为心肌细胞的过程中,Nkx2.5表达相对量的变化与细胞的形态变化可能有一定的相关。