PDF(Pubmed)
Abstract：
Microtubule affinity-regulating kinases (MARKs) are nonreceptor Ser/Thr protein kinases known to regulate cell polarity and microtubule dynamics in Caenorhabditis elegans, Drosophila, invertebrates, vertebrates, and mammals. An earlier study has shown that MARK4 is present at the ectoplasmic specialization and blood-testis barrier (BTB) in the seminiferous epithelium of adult rat testes. Here, we report the function of MARK4 and another isoform MARK2 in Sertoli cells at the BTB. Knockdown of MARK2, MARK4, or MARK2 and MARK4 by RNAi using the corresponding siRNA duplexes without apparent off-target effects was shown to impair tight junction (TJ)-permeability barrier at the Sertoli cell BTB. It also disrupted microtubule (MT)- and actin-based cytoskeletal organization within Sertoli cells. Although MARK2 and MARK4 were shown to share sequence homology, they likely regulated the Sertoli cell BTB and MT cytoskeleton differently. Disruption of the TJ-permeability barrier following knockdown of MARK4 was considerably more severe than loss of MARK2, though both perturbed the barrier. Similarly, loss of MARK2 affected MT organization in a different manner than the loss of MARK4. Knockdown of MARK2 caused MT bundles to be arranged around the cell periphery, whereas knockdown of MARK4 caused MTs to retract from the cell edge. These differences in effects on the TJ-permeability barrier are likely from the unique roles of MARK2 and MARK4 in regulating the MT cytoskeleton of the Sertoli cell.
摘要：
MARKs（微管亲和调节激酶）是非受体Ser/Thr蛋白激酶，已知可调节秀丽隐杆线虫的细胞极性和微管动力学，果蝇,无脊椎动物,脊椎动物和哺乳动物。较早的研究表明，MARK4存在于成年大鼠睾丸生精上皮的外质特化（EC）和血睾丸屏障（BTB）中。这里,我们报道了MARK4和另一种亚型MARK2在BTB支持细胞中的功能。使用相应的siRNA双链体通过RNAi对MARK2，MARK4或MARK2和MARK4的敲除没有明显的脱靶效应，已显示出损害支持细胞BTB的TJ通透性屏障。它还破坏了支持细胞内的微管（MT）和基于肌动蛋白的细胞骨架组织。尽管显示MARK2和MARK4具有相同的序列同源性,它们可能对支持细胞BTB和MT细胞骨架的调节不同。击倒MARK4后TJ渗透性屏障的破坏比MARK2的破坏严重得多，尽管两者都干扰了屏障。同样，MARK2的损失对MT组织的影响与MARK4的损失不同。MARK2的击倒导致MT束排列在细胞周围，而MARK4的敲除导致MT从细胞边缘缩回。对TJ通透性屏障的影响的这些差异可能是由于MARK2和MARK4在调节支持细胞的MT细胞骨架中的独特作用。
