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Li Z, Liu T, Gilmore A, Gómez NM, Mitchell CH, Li YP, Oursler MJ, Yang S. Regulator of G Protein Signaling Protein 12 (Rgs12) Controls Mouse Osteoblast Differentiation via Calcium Channel/Oscillation and Gαi-ERK Signaling. J Bone Miner Res 2019; 34:752-764. [PMID: 30489658 PMCID: PMC7675783 DOI: 10.1002/jbmr.3645] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/29/2018] [Revised: 11/13/2018] [Accepted: 11/17/2018] [Indexed: 12/11/2022]
Abstract
Bone homeostasis intimately relies on the balance between osteoblasts (OBs) and osteoclasts (OCs). Our previous studies have revealed that regulator of G protein signaling protein 12 (Rgs12), the largest protein in the Rgs super family, is essential for osteoclastogenesis from hematopoietic cells and OC precursors. However, how Rgs12 regulates OB differentiation and function is still unknown. To understand that, we generated an OB-targeted Rgs12 conditional knockout (CKO) mice model by crossing Rgs12fl/fl mice with Osterix (Osx)-Cre transgenic mice. We found that Rgs12 was highly expressed in both OB precursor cells (OPCs) and OBs of wild-type (WT) mice, and gradually increased during OB differentiation, whereas Rgs12-CKO mice (OsxCre/+ ; Rgs12fl/fl ) exhibited a dramatic decrease in both trabecular and cortical bone mass, with reduced numbers of OBs and increased apoptotic cell population. Loss of Rgs12 in OPCs in vitro significantly inhibited OB differentiation and the expression of OB marker genes, resulting in suppression of OB maturation and mineralization. Further mechanism study showed that deletion of Rgs12 in OPCs significantly inhibited guanosine triphosphatase (GTPase) activity and cyclic adenosine monophosphate (cAMP) level, and impaired Calcium (Ca2+ ) oscillations via restraints of major Ca2+ entry sources (extracellular Ca2+ influx and intracellular Ca2+ release from endoplasmic reticulum), partially contributed by the blockage of L-type Ca2+ channel mediated Ca2+ influx. Downstream mediator extracellular signal-related protein kinase (ERK) was found inactive in OBs of OsxCre/+ ; Rgs12fl/fl mice and in OPCs after Rgs12 deletion, whereas application of pertussis toxin (PTX) or overexpression of Rgs12 could rescue the defective OB differentiation via restoration of ERK phosphorylation. Our findings reveal that Rgs12 is an important regulator during osteogenesis and highlight Rgs12 as a potential therapeutic target for bone disorders. © 2018 American Society for Bone and Mineral Research.
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Affiliation(s)
- Ziqing Li
- Department of Anatomy and Cell Biology, School of Dental Medicine, University of Pennsylvania Philadelphia, PA 19104, USA
| | - Tongjun Liu
- Department of Oral Biology, School of Dental Medicine, University of Buffalo, State University of New York, Buffalo, NY 14215, USA
- Department of Implantology, Shandong Provincial Key Laboratory of Oral Biomedicine, School of Stomatology, Shandong University
- Department of Stomatology, the Jinan Central Hospital Affiliated to Shandong University, Jinan, Shandong province 250000, China
| | - Alyssa Gilmore
- Department of Oral Biology, School of Dental Medicine, University of Buffalo, State University of New York, Buffalo, NY 14215, USA
| | - Néstor Más Gómez
- Department of Anatomy and Cell Biology, School of Dental Medicine, University of Pennsylvania Philadelphia, PA 19104, USA
| | - Claire H Mitchell
- Department of Anatomy and Cell Biology, School of Dental Medicine, University of Pennsylvania Philadelphia, PA 19104, USA
- Department of Physiology, School of Medicine, University of Pennsylvania Philadelphia, PA 19104, USA
| | - Yi-ping Li
- Department of Pathology, University of Alabama in Birmingham, Birmingham, AL 35294, USA
| | - Merry J Oursler
- Department of Medicine, Endocrine Research Unit, Mayo Clinic, Rochester, MN 55905, USA
| | - Shuying Yang
- Department of Anatomy and Cell Biology, School of Dental Medicine, University of Pennsylvania Philadelphia, PA 19104, USA
- The Penn Center for Musculoskeletal Disorders, University of Pennsylvania Philadelphia, PA 19104, USA
- Department of Oral Biology, School of Dental Medicine, University of Buffalo, State University of New York, Buffalo, NY 14215, USA
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