title: Orai1 mediates osteogenic differentiation via BMP signaling pathway in bone marrow mesenchymal stem cells.
abstract: Orai1 is a pore-subunit of store-operated Ca(2+) release-activated Ca(2+) (CRAC) channel that mediates Ca(2+) influx in most non-excitable cells via store-operated Ca(2+) entry (SOCE) mechanism. We previously demonstrated that Orai1 is involved in mediating osteogenic potential of mesenchymal stem cells (MSCs), but the underlying mechanism of this function remains unknown. Here, we report that Orai1 mediates osteogenic differentiation via bone morphogenic protein (BMP) signaling pathway in bone marrow MSCs (BMSCs). In osteogenic conditions, BMSCs derived from wild-type mice underwent osteoblastic differentiation and induced mineralization as demonstrated by increased alkaline phosphatase activity and alizarin red S staining, respectively. The expression of Runx2, a master regulator of osteoblast differentiation, and osteogenic differentiation markers were markedly increased in wild-type BMSCs under osteogenic conditions. In contrast, osteogenic conditions failed to induce such effects in BMSCs derived from Orai1-deficient (Orai1(-/-)) mice, indicating that Orai1 is, in part, necessary for osteogenic differentiation of MSCs. We also found that BMP2 successfully induced phosphorylation of Smad1/5/8, the immediate effector molecules of BMP signaling, in wild-type BMSCs, but failed to do so in Orai1(-/-) BMSCs. Downstream target genes of BMP signaling pathway were consistently increased by osteogenic conditions in wild-type BMSCs, but not in Orai1(-/-) BMSCs, suggesting a novel molecular link between Orai1 and BMP signaling pathway in the osteogenic differentiation process. Further functional studies demonstrated that activation of BMP signaling rescues osteogenic differentiation capacity of Orai1(-/-) BMSCs. In conclusion, Orai1 regulates osteogenic differentiation through BMP signaling, and the Orai1-BMP signaling may be a possible therapeutic target for treating bone-related diseases.
authors.affiliation: The Shapiro Family Laboratory of Viral Oncology and Aging Research, UCLA School of Dentistry, Los Angeles, CA 90095, USA.
authors.forename: Sung Hee
authors.initials: SH
authors.lastname: Lee
authors.affiliation: The Shapiro Family Laboratory of Viral Oncology and Aging Research, UCLA School of Dentistry, Los Angeles, CA 90095, USA.
authors.forename: Yongtae
authors.initials: Y
authors.lastname: Park
authors.affiliation: The Shapiro Family Laboratory of Viral Oncology and Aging Research, UCLA School of Dentistry, Los Angeles, CA 90095, USA.
authors.forename: Minju
authors.initials: M
authors.lastname: Song
authors.affiliation: Department of Physiology, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095, USA.
authors.forename: Sonal
authors.initials: S
authors.lastname: Srikanth
authors.affiliation: The Shapiro Family Laboratory of Viral Oncology and Aging Research, UCLA School of Dentistry, Los Angeles, CA 90095, USA.
authors.forename: Sol
authors.initials: S
authors.lastname: Kim
authors.affiliation: The Shapiro Family Laboratory of Viral Oncology and Aging Research, UCLA School of Dentistry, Los Angeles, CA 90095, USA; UCLA Jonsson Comprehensive Cancer Center, Los Angeles, CA 90095, USA.
authors.forename: Mo K
authors.initials: MK
authors.lastname: Kang
authors.affiliation: Department of Physiology, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095, USA.
authors.forename: Yousang
authors.initials: Y
authors.lastname: Gwack
authors.affiliation: The Shapiro Family Laboratory of Viral Oncology and Aging Research, UCLA School of Dentistry, Los Angeles, CA 90095, USA; UCLA Jonsson Comprehensive Cancer Center, Los Angeles, CA 90095, USA; Department of Medicine, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095, USA.
authors.forename: No-Hee
authors.initials: NH
authors.lastname: Park
authors.affiliation: The Shapiro Family Laboratory of Viral Oncology and Aging Research, UCLA School of Dentistry, Los Angeles, CA 90095, USA; UCLA Jonsson Comprehensive Cancer Center, Los Angeles, CA 90095, USA. Electronic address: rkim@dentistry.ucla.edu.
authors.forename: Reuben H
authors.initials: RH
authors.lastname: Kim
authors.affiliation: The Shapiro Family Laboratory of Viral Oncology and Aging Research, UCLA School of Dentistry, Los Angeles, CA 90095, USA; UCLA Jonsson Comprehensive Cancer Center, Los Angeles, CA 90095, USA. Electronic address: kshin@dentistry.ucla.edu.
authors.forename: Ki-Hyuk
authors.initials: KH
authors.lastname: Shin
mesh_terms: D000818:Animals; D001854:Bone Marrow Cells / Q000166:cytology / Q000502:physiology; D019485:Bone Morphogenetic Proteins / Q000378:metabolism*; D002113:Calcification, Physiologic / Q000502:physiology*; D020013:Calcium Signaling; D002454:Cell Differentiation / Q000502:physiology; D002478:Cells, Cultured; D059630:Mesenchymal Stem Cells / Q000166:cytology* / Q000502:physiology*; D051379:Mice; D010012:Osteogenesis / Q000502:physiology*; D015398:Signal Transduction / Q000502:physiology*
chemical_list: D019485:Bone Morphogenetic Proteins
keywords: BMP2; Bone marrow stem cells; Orai1; Osteogenic differentiation