Effects of a miR-31,Runx2, andSatb2Regulatory Loop on the Osteogenic Differentiation of Bone Mesenchymal Stem Cells

Abstract

Recently, a cohort of miRNAs, including miR-31, was reported to be downregulated during osteogenic induction by miR microarray analysis. It remains unclear how changes in miR-31 expression collaborate with bone transcription factors to activate the biological pathways that regulate the differentiation of bone mesenchymal stem cells (BMSCs). Here the effects of miR-31, Runx2, and Satb2 on the osteogenic differentiation of BMSCs were investigated using mimics and inhibitors of miR-31, small interfering RNA for knockdown of Runx2 and plasmids for overexpression of Runx2. Our results showed that miR-31 expression decreased progressively in BMSC cultures during differentiation. Inhibition of miR-31 dramatically increased the alkaline phosphatase activity and mineralization in BMSC cultures. Additionally, miR-31 diminished the levels of the Satb2 protein without significantly affecting Satb2 mRNA levels, and Runx2 directly repressed miR-31 expression. Overexpression of miR-31 significantly reduced expression of the osteogenic transcription factors OPN, BSP, OSX, and OCN, but not Runx2. Furthermore, the high expression of miR-31 in BMSCs cultured in the proliferation medium repressed Satb2 protein levels, which may contribute to the maintenance of BMSCs in an undifferentiated state. In conclusion, our results suggest that a Runx2, Satb2, and miR-31 regulatory mechanism may play an important role in inducing BMSC osteogenic differentiation. The results of this study provide us with a better understanding of the molecular mechanisms that govern the BMSC fate.

MicroRNA‐31a‐5p from aging BMSCs links bone formation and resorption in the aged bone marrow microenvironment

“…The reduced protein levels of SATB2 suggested that expression of miR‐31a‐5p was negatively correlated with SATB2 levels. We used TargetScan to predict the target of miR‐31a‐5p and found that miR‐31a‐5p could bind to the 3′‐untranslated region (3′UTR) of SATB2 (Figure 3g), a pluripotency transcription factor, which has been previously demonstrated (Deng, Wu et al., 2013; Ge et al., 2015). To further demonstrate whether miR‐31a‐5p regulated osteogenesis via SATB2, the osteogenic capacity of si‐SATB2 treated BMSCs was rejuvenated by miR‐31a‐5p inhibition (Figure 3h,i).…”

“…It has been reported that miR‐31a‐5p negatively regulates skeletogenesis and osteogenesis (Deng, Wu et al., 2013; Jin et al., 2016; Stepicheva, & Song, 2015; Weilner et al., 2016). Previous studies also demonstrated that decreased stemness and increased senescence are the primary causes of declines in osteogenic differentiation of BMSCs (Fehrer, & Lepperdinger, 2005; Zhou et al., 2016).…”

“…The increased level of miR‐31a‐5p was further confirmed by the estrogen‐deficient aging model, replicative aging model and human aging model. SATB2 is a target gene of miR‐31a‐5p, which has been proven by some prior studies (Aprelikova et al., 2010; Deng, Weng et al., 2013; Deng, Zhou et al., 2013). Our previous investigation has demonstrated that SATB2, as a transcriptional regulator, functions broadly (Dong et al., 2015) and is involved in osteogenic differentiation in age‐related BMSCs (Strickland, Wasserman, Giassi, Djordjevic, & Parra‐Herran, 2016; Zhou et al., 2016).…”

“…Our previous results also demonstrated that SATB2 improves the stemness capacity and osteogenic differentiation of aged human BMSCs (Zhou et al., 2016). In addition, miR‐31a‐5p has been reported to directly target bone relevant markers, such as RUNX2, OSX, and DKK1 (Baglio, Devescovi, Granchi, & Baldini, 2013; Deng, Wu et al., 2013; Gao et al., 2011; Lv et al., 2017). Furthermore, it has been reported that regulation of miR‐31a‐5p expression could be used to modulate senescence‐related pathological conditions such as cancer, and the aging process (Capri et al., 2017; Cho, Dimri, & Dimri, 2015), which highlights us the important role of miR‐31a‐5p in cellular senescence.…”

Scaffold‐Based microRNA Therapies in Regenerative Medicine and Cancer

“…This work highlighted a Runx2/Satb2/miR-31 regulatory loop activated by BMP to play a vital function in ASC osteogenesis and bone regeneration. Having previously reported that knockdown of endogenous miR-31 in vitro significantly improved the osteogenic capacity of BM-MSCs, [152] the group went on to assess the therapeutic potential of lentivirus-miR-31-modified BM-MSCs cultured on poly(glycerol sebacate) scaffolds. [46] Results demonstrated that miR-31 inhibition could successfully enhance bone repair in the defect area.…”