Undercarboxylated osteocalcin inhibits the early differentiation of osteoclast mediated by Gprc6a

PeerJ

article

Hailong Wang¹  Jinqiao Li¹  Zihan Xu¹  Feng Wu¹  Hongyu Zhang¹  Chao Yang¹  Jian Chen¹  Bai Ding¹  Xiukun Sui¹  Zhifeng Guo¹  Yinghui Li¹  Zhongquan Dai¹ 

[1] State Key Laboratory of Space Medicine Fundamentals and Application, China Astronaut Research and Training Center;Space Engineering University;Department of Orthopaedics, Sir Run Run Shaw Hospital, School of Medicine, Zhejiang University

关键词: Undercarboxylated osteocalcin;    Osteoclast;    Gprc6a;    Differentiation;    Bone homeostasis;    Bone resorption;   

DOI  :  10.7717/peerj.10898

学科分类：社会科学、人文和艺术（综合）

来源: Inra

【 摘 要 】

Osteocalcin (OCN) was the most abundant noncollagen protein and considered as an endocrine factor. However, the functions of Undercarboxylated osteocalcin (ucOCN) on osteoclast and bone resorption are not well understood. In the present study, preosteoclast RAW264.7 cells and bone marrow mononuclear cells (BMMs) were treated with ucOCN purified from prokaryotic bacteria. Our results showed that ucOCN attenuated the proliferation of RAW264.7 cells with a concentration dependant manner by MTS assay. Scrape wounding assay revealed the decreased motility of RAW264.7 cells after ucOCN treatment. RT-qPCR results manifested the inhibitory effects of ucOCN on the expression of osteoclastic marker genes in RAW264.7 cells during inducing differentiation of RANKL. It was also observed that ucOCN inhibited the formation of multinucleated cells from RAW264.7 cells and BMMs detected by TRAP staining. The number and area of bone resorb pits were also decreased after treatment with ucOCN during their osteoclast induction by toluidine blue staining. The formation and integrity of the osteoclast actin ring were impaired by ucOCN by immunofluorescent staining. Time dependant treatment of ucOCN during osteoclastic induction demonstrated the inhibitory effects mainly occurred at the early stage of osteoclastogenesis. Signaling analysis of luciferase activity of the CRE or SRE reporter and ERK1/2 phosphorylation showed the selective inhibitor or siRNA of Gprc6a (a presumptive ucOCN receptor) could attenuate the promotion of ucOCN on CRE-luciferase activity. Taken together, we provided the first evidence that ucOCN had negative effects on the early differentiation and bone resorption of osteoclasts via Gprc6a.

【 授权许可】

CC BY