Journal Article

DEPTOR regulates osteogenic differentiation via inhibiting MEG3-mediated activation of BMP4 signaling and is involved in osteoporosis

Chen, Si, Jia, Lingfei, Zheng, Yunfei, Zhang, Shan, Zhou, Yongsheng

2018

Overview

Background The mammalian target of rapamycin (mTOR) pathway plays a significant role in osteogenic differentiation and bone maintenance. As the only known endogenous inhibitor of mTOR function, DEP domain containing mTOR interacting protein (DEPTOR) is potentially involved in stem cell differentiation, although the pathophysiological significance and its molecular mechanisms remain unclear. The present study aimed to elucidate the effects of DEPTOR on the progress of osteoporosis and investigate the underlying molecular mechanisms of osteogenic regulation. Methods An ovariectomy mouse model with decreased bone formation and osteogenic induction with bone marrow mesenchymal stem cells (BMSCs) were used to investigate the relationship between DEPTOR and osteogenic events. A loss-of-function investigation was then performed to explore the role of DEPTOR in the osteogenic differentiation of BMSCs both in vitro and in vivo. Finally, long noncoding RNA (lncRNA) and mRNA sequences were investigated to reveal the underlying mechanisms of DEPTOR in osteogenic regulation. RNA interference, western blotting, and chromatin immunoprecipitation assays were performed for further mechanistic determination. Results The results indicated that DEPTOR contributes to the progress of osteoporosis, and higher expression of Deptor was observed in osteoporotic bones. The expression of DEPTOR was reduced during the osteogenic differentiation of BMSCs, and knockdown of DEPTOR promoted BMSC osteogenesis in vitro and in vivo. lncRNA and mRNA sequences indicated that knockdown of DEPTOR upregulated the expression of maternally expressed 3 (nonprotein coding) ( MEG3 ), which subsequently activated bone morphogenetic protein 4 (BMP4) signaling. Furthermore, DEPTOR could bind to a specific region (− 1000 bp ~ 0) of the MEG3 promoter to regulate its transcription, and inhibition of MEG3 reduced BMP4 activation triggered by DEPTOR knockdown. Conclusions Taken together, our study revealed a novel function of DEPTOR in osteogenic differentiation by inhibiting MEG3-mediated activation of BMP4 signaling, which suggested that DEPTOR could be a therapeutic target for bone loss diseases and skeletal tissue regeneration.

• Publisher: BioMed Central,BioMed Central Ltd,Springer Nature B.V,BMC
• Subject: Animals / Antibiotics / Biomedical and Life Sciences / Biomedical Engineering and Bioengineering / Bone engineering / Bone growth / Bone loss / Bone marrow / Bone morphogenetic protein 4 / Bone Morphogenetic Protein 4 - genetics / Bone Morphogenetic Protein 4 - metabolism / Bone morphogenetic proteins / Cancer / Cell Biology / Cell Differentiation - genetics / Cell Differentiation - physiology / Chromatin / DEP domain containing mTOR interacting protein / Dosage and administration / Female / Fractures / Gene expression / Genetic aspects / Immunoprecipitation / Intracellular Signaling Peptides and Proteins - genetics / Intracellular Signaling Peptides and Proteins - metabolism / Kinases / Life Sciences / Maternally expressed 3 (nonprotein coding) / Mesenchymal Stem Cells - drug effects / Mesenchymal Stem Cells - metabolism / Mesenchyme / Mice / Mice, Inbred C57BL / Molecular modelling / Older people / Osteogenesis / Osteogenesis - genetics / Osteogenesis - physiology / Osteoporosis / Osteoporosis - genetics / Osteoporosis - metabolism / Osteoporosis - physiopathology / Ovariectomy / Prognosis / Proteins / Rapamycin / Regeneration / Regenerative Medicine/Tissue Engineering / RNA, Long Noncoding - genetics / RNA, Long Noncoding - metabolism / RNA-mediated interference / Signal Transduction - genetics / Signal Transduction - physiology / Stem cell transplantation / Stem Cells / Therapeutic applications / Tissue engineering / TOR protein / Transcription / Western blotting