title: CaMKK2 Suppresses Muscle Regeneration through the Inhibition of Myoblast Proliferation and Differentiation.
abstract: Skeletal muscle has a major role in locomotion and muscle disorders are associated with poor regenerative efficiency. Therefore, a deeper understanding of muscle regeneration is needed to provide a new insight for new therapies. CaMKK2 plays a role in the calcium/calmodulin-dependent kinase cascade; however, its role in skeletal muscle remains unknown. Here, we found that CaMKK2 expression levels were altered under physiological and pathological conditions including postnatal myogensis, freeze or cardiotoxin-induced muscle regeneration, and Duchenne muscular dystrophy. Overexpression of CaMKK2 suppressed C2C12 myoblast proliferation and differentiation, while inhibition of CaMKK2 had opposite effect. We also found that CaMKK2 is able to activate AMPK in C2C12 myocytes. Inhibition of AMPK could attenuate the effect of CaMKK2 overexpression, while AMPK agonist could abrogate the effect of CaMKK2 knockdown on C2C12 cell differentiation and proliferation. These results suggest that CaMKK2 functions as an AMPK kinase in muscle cells and AMPK mediates the effect of CaMKK2 on myoblast proliferation and differentiation. Our data also indicate that CaMKK2 might inhibit myoblast proliferation through AMPK-mediated cell cycle arrest by inducing cdc2-Tyr15 phosphorylation and repress differentiation through affecting PGC1α transcription. Lastly, we show that overexpressing CaMKK2 in the muscle of mice via electroporation impaired the muscle regeneration during freeze-induced injury, indicating that CaMKK2 could serve as a potential target to treat patients with muscle injury or myopathies. Together, our study reveals a new role for CaMKK2 as a negative regulator of myoblast differentiation and proliferation and sheds new light on the molecular regulation of muscle regeneration.
authors: Key Laboratory of Food Safety Research, Institute for Nutritional Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, University of Chinese Academy of Sciences, Shanghai 200031, China. yecheng@sibs.ac.cn.
authors: Cheng
authors: C
authors: Ye
authors: Key Laboratory of Food Safety Research, Institute for Nutritional Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, University of Chinese Academy of Sciences, Shanghai 200031, China. zhangduo@sibs.ac.cn.
authors: Duo
authors: D
authors: Zhang
authors: Department of Neuromuscular Disease, Children's Hospital of Fudan University, Shanghai 201102, China. zhaolei1117@126.com.
authors: Lei
authors: L
authors: Zhao
authors: Key Laboratory of Food Safety Research, Institute for Nutritional Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, University of Chinese Academy of Sciences, Shanghai 200031, China. liyan02@sibs.ac.cn.
authors: Yan
authors: Y
authors: Li
authors: Key Laboratory of Food Safety Research, Institute for Nutritional Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, University of Chinese Academy of Sciences, Shanghai 200031, China. xhyao@sibs.ac.cn.
authors: Xiaohan
authors: X
authors: Yao
authors: Key Laboratory of Food Safety Research, Institute for Nutritional Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, University of Chinese Academy of Sciences, Shanghai 200031, China. wanghui01@sibs.ac.cn.
authors: Hui
authors: H
authors: Wang
authors: Key Laboratory of Food Safety Research, Institute for Nutritional Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, University of Chinese Academy of Sciences, Shanghai 200031, China. zhangshengjie@sibs.ac.cn.
authors: Shengjie
authors: S
authors: Zhang
authors: Key Laboratory of Food Safety Research, Institute for Nutritional Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, University of Chinese Academy of Sciences, Shanghai 200031, China. liuwei01@sibs.ac.cn.
authors: Wei
authors: W
authors: Liu
authors: Key Laboratory of Food Safety Research, Institute for Nutritional Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, University of Chinese Academy of Sciences, Shanghai 200031, China. hccao@sibs.ac.cn.
authors: Hongchao
authors: H
authors: Cao
authors: Key Laboratory of Food Safety Research, Institute for Nutritional Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, University of Chinese Academy of Sciences, Shanghai 200031, China. sxyu@sibs.ac.cn.
authors: Shuxian
authors: S
authors: Yu
authors: Shanghai Xuhui Central Hospital, Shanghai Clinical Center, Chinese Academy of Sciences, Shanghai 200031, China. candywang666@hotmail.com.
authors: Yucheng
authors: Y
authors: Wang
authors: Department of Endocrinology and Metabolism, Zhongshan Hospital, Fudan University, Shanghai 200031, China. superseraph@126.com.
authors: Jingjing
authors: J
authors: Jiang
authors: Key Laboratory of Food Safety Research, Institute for Nutritional Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, University of Chinese Academy of Sciences, Shanghai 200031, China. huiwang@sibs.ac.cn.|Key Laboratory of Food Safety Risk Assessment, Ministry of Health, Beijing 100021, China. huiwang@sibs.ac.cn.
authors: Hui
authors: H
authors: Wang
authors: Department of Neuromuscular Disease, Children's Hospital of Fudan University, Shanghai 201102, China. xihual@vip.sina.com.
authors: Xihua
authors: X
authors: Li
authors: Key Laboratory of Food Safety Research, Institute for Nutritional Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, University of Chinese Academy of Sciences, Shanghai 200031, China. yinghao@sibs.ac.cn.|Shanghai Xuhui Central Hospital, Shanghai Clinical Center, Chinese Academy of Sciences, Shanghai 200031, China. yinghao@sibs.ac.cn.|Key Laboratory of Food Safety Risk Assessment, Ministry of Health, Beijing 100021, China. yinghao@sibs.ac.cn.
authors: Hao
authors: H
authors: Ying
mesh_terms: D055372:AMP-Activated Protein Kinases / Q000378:metabolism*; D000818:Animals; D054737:Calcium-Calmodulin-Dependent Protein Kinase Kinase / Q000235:genetics / Q000378:metabolism*; D002454:Cell Differentiation; D002460:Cell Line; D049109:Cell Proliferation; D051379:Mice; D018482:Muscle, Skeletal / Q000502:physiology*; D032446:Myoblasts / Q000166:cytology* / Q000378:metabolism; D012038:Regeneration; D015398:Signal Transduction; D015854:Up-Regulation
chemical_list: D054737:Calcium-Calmodulin-Dependent Protein Kinase Kinase; C517700:Camkk2 protein, mouse; D055372:AMP-Activated Protein Kinases
keywords: AMPK; CaMKK2; differentiation; muscle regeneration; proliferation