StarD7及Wnt/β-catenin信号通路对Annexin5刺激大鼠睾丸Leydig细胞合成睾酮的影响

Our previous study found that ,in rat Leydig cells, annexin 5 (A5) can promote the testosterone(T) synthesis by regulating cell StarD7 expression. Beta-catenin also participate in the process of T synthesis stimulated by A5. It has been reported, beta catenin through the TCF/LEF combind with StarD7 promoter, and then modulate StarD7 gene expression. Based on these findings, this research intends to investigate the mechanism of beta-catenin and StarD7 participate in T synthesis. Aim to clearify: (1) effect of starD7 and Wnt/beta-catenin pathway on upstream key molecular expression of T synthesis in Leydig cells. (2) A5 augument beta-catenin into the nucleus, the beta - catenin and TCF/LEF form complex, and then combinded with cis role element (TCF4) of StarD7 promoter through the TCF/LEF, promote StarD7 transcription and expression in Leydig cells, and further increase T synthesis.This research would find a new local mechanism of T synthetic way and provide theoretical basis for the male reproductive endocrine research.

我们先前的研究发现，在大鼠睾丸Leydig细胞，膜联蛋白5(A5)是通过调节细胞StarD7的表达，进而促进睾酮(T)的合成；β-catenin也参与A5调节T合成的过程。已有报道，β-catenin通过TCF/LEF与StarD7启动子结合，进而促进StarD7基因的表达。基于这些发现，本课题拟对β-catenin和StarD7参与T合成的机制进行研究。明确：（1）StarD7和Wnt/β-catenin通路参与Annexin 5刺激Leydig细胞T合成的过程；（2）StarD7和Wnt/β-catenin通路通过影响T合成上游关键分子进而影响T合成的。以期发现一条新的T局部合成途径并阐明其机制，为男性生殖内分泌的研究提供理论基础。

为了研究StarD7及Wnt/β-catenin信号通路在annexin5作用Leydig细胞合成T中过程中的作用，我们用Wnt/β-catenin信号通路特异性阻断剂Dkk1作用于Leydig细胞，Dkk1的单独作用下，睾酮、StarD7、β-catenin、3β-HSD、17β-HSD的表达均有所下降，且在Dkk1和A5共同作用下，与单独A5作用相比，睾酮、StarD7、β-catenin、3β-HSD的表达均有不同程度的下降，由此提示Wnt/β-catenin信号通路参与annexin5调控Leydig细胞T合成的生理过程；同时利用siRNA-StarD7转染培养Leydig细胞，测定annexin 5刺激转染后Leydig 细胞的T含量，结果显示在StarD7的表达被干扰后，睾酮合成明显下降，其关键合成调节酶3β-HSD、17β-HSD在mRNA水平和蛋白水平均有显著性下降。由此说明，StarD7的表达调节了Wnt/β-catenin信号通路对睾酮合成关键调节酶的调控，从而调节睾酮合成。