title: MiR-132 regulates osteogenic differentiation via downregulating Sirtuin1 in a peroxisome proliferator-activated receptor β/δ-dependent manner.
abstract: MicroRNAs (miRNAs) play significant roles in multiple diseases by regulating the expression of their target genes. Type 2 diabetes mellitus (T2DM) is a chronic endocrine and metabolic disease with complex mechanisms. T2DM can result in diabetic osteoporosis (DO), which is characterized by bone loss, decreased bone mineral density and increased bone fractures. The promotion of osteogenic differentiation of osteoblasts is an effective way to treat osteoporosis. In the present study, high glucose (HG) and free fatty acids (FFA) were employed to mimic T2DM in MC3T3-E1 cells. To induce osteogenic differentiation, MC3T3-E1 cells were cultured in osteogenic medium. The results showed that osteogenic differentiation was significantly suppressed by HG and FFA. We found that miR-132 expression was significantly upregulated and much higher in HG-FFA-induced cells than other selected miRNAs, indicating that miR-132 might play an important role in DO. Furthermore, overexpression of miR-132 markedly inhibited the expression of key markers of osteogenic differentiation and alkaline phosphatase (ALP) activity. Reciprocally, inhibition of miR-132 restored osteogenic differentiation, even under treatment with HG-FFA. We also showed that Sirtuin 1 (Sirt1) was one of the target genes of miR-132, whose expression was controlled by miR-132. Ectopic expression of Sirt1 reversed the decrease in osteogenic differentiation caused by miR-132 and HG-FFA. These results demonstrated the direct role of miR-132 in suppressing osteogenic differentiation through downregulating Sirt1. Moreover, we demonstrated that peroxisome proliferator-activated receptor β/δ (PPARβ/δ) was a downstream molecule of Sirt1, and its knockout by PPARβ/δ siRNA significantly abolished the promotive effects of Sirt1 on osteogenic differentiation, indicating that Sirt1 functioned in a PPARβ/δ-dependent manner. Taken together, we provide crucial evidence that miR-132 plays a key role in regulating osteogenic differentiation through Sirt1 in a PPARβ/δ-dependent manner, indicating that miR-132 and Sirt1-PPARβ/δ may act as potential therapeutic targets for T2DM-induced osteoporosis.
authors.affiliation: Department of Orthopaedics, Chengdu Military General Hospital, Chengdu, 610083, China.
authors.forename: Kai
authors.initials: K
authors.lastname: Gong
authors.affiliation: Department of Orthopaedics, Chengdu Military General Hospital, Chengdu, 610083, China.
authors.forename: Bo
authors.initials: B
authors.lastname: Qu
authors.affiliation: Department of Orthopaedics, Chengdu Military General Hospital, Chengdu, 610083, China.
authors.forename: Dongfa
authors.initials: D
authors.lastname: Liao
authors.affiliation: Department of Orthopaedics, Chengdu Military General Hospital, Chengdu, 610083, China.
authors.forename: Da
authors.initials: D
authors.lastname: Liu
authors.affiliation: Department of Orthopaedics, Chengdu Military General Hospital, Chengdu, 610083, China.
authors.forename: Cairu
authors.initials: C
authors.lastname: Wang
authors.affiliation: Department of Orthopaedics, Chengdu Military General Hospital, Chengdu, 610083, China.
authors.forename: Jingsong
authors.initials: J
authors.lastname: Zhou
authors.affiliation: Department of Orthopaedics, Chengdu Military General Hospital, Chengdu, 610083, China. Electronic address: xianmingpanxj@163.com.
authors.forename: Xianming
authors.initials: X
authors.lastname: Pan
mesh_terms: D000818:Animals; D041702:BALB 3T3 Cells; D002454:Cell Differentiation / Q000502:physiology; D015536:Down-Regulation / Q000502:physiology; D018507:Gene Expression Regulation, Developmental / Q000502:physiology; D051379:Mice; D035683:MicroRNAs / Q000378:metabolism*; D010006:Osteoblasts / Q000166:cytology / Q000473:pathology*; D010012:Osteogenesis / Q000502:physiology*; D047495:PPAR gamma / Q000378:metabolism*; D048068:PPAR-beta / Q000378:metabolism*; D056564:Sirtuin 1 / Q000378:metabolism*
chemical_list: C546976:MIRN132 microRNA, mouse; D035683:MicroRNAs; D047495:PPAR gamma; D048068:PPAR-beta; C470545:Sirt1 protein, mouse; D056564:Sirtuin 1
keywords: Diabetic osteoporosis; MiR-132; Osteogenic differentiation; Peroxisome proliferator-activated receptor β/δ; Sirtuin1