AMP激活的蛋白激酶(AMPK)是一种多功能激酶,通过CLIP-170磷酸化调节微管(MT)动态不稳定性;然而,其在体内的生理相关性仍有待阐明。在这项研究中,我们确定了AMPK的活性形式,位于心脏的插入盘上,心肌细胞之间存在的特定细胞-细胞连接。一种收缩抑制剂,MYK-461阻止了AMPK在插入圆盘上的定位,MYK-461的去除逆转了这种效果,表明AMPK的定位受机械应力的调节。延时成像分析表明,AMPK对CLIP-170Ser-311磷酸化的抑制作用导致MT在插入的圆盘上积累。有趣的是,MYK-461以CLIP-170磷酸化依赖性方式增加心肌细胞的单个细胞面积。此外,心脏特异性CLIP-170S311A转基因小鼠表现出心肌细胞的伸长以及累积的MTs,导致心脏收缩逐渐下降。总之,这些发现表明,AMPK通过在插入的圆盘上CLIP-170的稳态磷酸化来调节MT的周转,从而调节心肌细胞的细胞形状和长宽比。
AMP-activated protein kinase (AMPK) is a multifunctional kinase that regulates microtubule (MT) dynamic instability through CLIP-170 phosphorylation; however, its physiological relevance in vivo remains to be elucidated. In this study, we identified an active form of AMPK localized at the intercalated disks in the heart, a specific cell-cell junction present between cardiomyocytes. A contractile inhibitor, MYK-461, prevented the localization of AMPK at the intercalated disks, and the effect was reversed by the removal of MYK-461, suggesting that the localization of AMPK is regulated by mechanical stress. Time-lapse imaging analysis revealed that the inhibition of CLIP-170 Ser-311 phosphorylation by AMPK leads to the accumulation of MTs at the intercalated disks. Interestingly, MYK-461 increased the individual cell area of cardiomyocytes in CLIP-170 phosphorylation-dependent manner. Moreover, heart-specific CLIP-170 S311A transgenic mice demonstrated elongation of cardiomyocytes along with accumulated MTs, leading to progressive decline in cardiac contraction. In conclusion, these findings suggest that AMPK regulates the cell shape and aspect ratio of cardiomyocytes by modulating the turnover of MTs through homeostatic phosphorylation of CLIP-170 at the intercalated disks.