A novel long noncoding RNA PGC1β-OT1 regulates adipocyte and osteoblast differentiation through antagonizing miR-148a-3p

Long noncoding RNAs (LncRNAs) have been implicated in the regulation of adipocyte and osteoblast differentiation. However, the functional contributions of LncRNAs to adipocyte or osteoblast differentiation remain largely unexplored. In the current study we have identified a novel LncRNA named peroxisome proliferator-activated receptor gamma coactivator-1 beta-OT1 (PGC1 beta-OT1). The expression levels of PGC1 beta-OT1 were altered during adipogenic and osteogenic differentiation from progenitor cells. 5'- and 3'-rapid amplification of cDNA ends (RACE) revealed that PGC1 beta-OT1 is 1759 nt in full length. Overexpression of PGC1 beta-OT1 in progenitor cells inhibited adipogenic differentiation, whereas silencing of endogenous PGC1 beta-OT1 induced adipogenic differentiation. By contrast, overexpression of PGC1 beta-OT1 in progenitor cells stimulated, whereas silencing of PGC1 beta-OT1 inhibited osteogenic differentiation. In vivo experiment showed that silencing of endogenous PGC1 beta-OT1 in marrow stimulated fat accumulation and decreased osteoblast differentiation in mice. Mechanism investigations revealed that PGC1 beta-OT1 contains a functional miR-148a-3p binding site. Overexpression of the mutant PGC1 beta-OT1 with mutation at the binding site failed to regulate either adipogenic or osteogenic differentiation. In vivo crosslinking combined with affinity purification studies demonstrated that PGC1 beta-OT1 physically associated with miR148a-3p through the functional miR-148a-3p binding site. Furthermore, PGC1 beta-OT1 affected the expression of endogenous miR-148a-3p and its target gene lysine-specific demethylase 6b (KDM6B). Supplementation of miR-148a-3p in progenitor cells blocked the inhibitory effect of PGC1 beta-OT1 on adipocyte formation. Moreover, overexpression of Kdm6b restored the osteoblast differentiation which was inhibited by silencing of endogenous PGC1 beta-OT. Our studies provide evidences that the novel LncRNA PGC1 beta-OT1 reciprocally regulates adipogenic and osteogenic differentiation through antagonizing miR-148a-3p and enhancing KDM6B effect.