AUTHOR=Sun Jie , Qiao Yan-Ning , Tao Tao , Zhao Wei , Wei Li-Sha , Li Ye-Qiong , Wang Wei , Wang Ye , Zhou Yu-Wei , Zheng Yan-Yan , Chen Xin , Pan Hong-Chun , Zhang Xue-Na , Zhu Min-Sheng 

TITLE=Distinct Roles of Smooth Muscle and Non-muscle Myosin Light Chain-Mediated Smooth Muscle Contraction

JOURNAL=Frontiers in Physiology

VOLUME=11

YEAR=2020

URL=https://www.frontiersin.org/journals/physiology/articles/10.3389/fphys.2020.593966

DOI=10.3389/fphys.2020.593966

ISSN=1664-042X

ABSTRACT=<p>Both smooth muscle (SM) and non-muscle (NM) myosin II are expressed in hollow organs such as the bladder and uterus, but their respective roles in contraction and corresponding physiological functions remain to be determined. In this report, we assessed their roles by analyzing mice deficient of <italic>Myl9</italic>, a gene encoding the SM myosin regulatory light chain (SM RLC). We find that global <italic>Myl9</italic>-deficient bladders contracted with an apparent sustained phase, despite no initial phase. This sustained contraction was mediated by NM myosin RLC (NM RLC) phosphorylation by myosin light chain kinase (MLCK). NM myosin II was expressed abundantly in the uterus and young mice bladders, of which the force was accordingly sensitive to NM myosin inhibition. Our findings reveal distinct roles of SM RLC and NM RLC in SM contraction.</p>