title: microRNA-25 targets PKCζ and protects osteoblastic cells from dexamethasone via activating AMPK signaling.
abstract: AMP-activated protein kinase (AMPK) activation could protect osteoblasts from dexamethasone (Dex). This study aims to provoke AMPK activation via microRNA downregulation of its negative regulator protein kinase C ζ (PKCζ). Results show that microRNA-25-5p (miR-25-5p) targets PKCζ's 3' untranslated regions (UTRs). Forced-expression of miR-25 downregulated PKCζ and activated AMPK in human osteoblastic cells (OB-6 and hFOB1.19 lines), which thereafter protected cells from Dex. Reversely, expression of antagomiR-25, the miR-25 inhibitor, upregulated PKCζ and inhibited AMPK activation, exacerbating Dex damages. Notably, PKCζ shRNA knockdown similarly activated AMPK and protected osteoblastic cells from Dex. AMPK activation was required for miR-25-induced osteoblastic cell protection. AMPKα shRNA or dominant negative mutation almost completely blocked miR-25-induced cytoprotection against Dex. Further studies showed that miR-25 expression increased NADPH activity and suppressed Dex-induced oxidative stress in osteoblastic cells. Such effects by miR-25 were abolished with AMPKα knockdown or mutation. Significantly, miR-25-5p level was increased in patients' necrotic femoral head tissues, which was correlated with PKCζ downregulation and AMPK hyper-activation. These results suggest that miR-25-5p targets PKCζ and protects osteoblastic cells from Dex possibly via activating AMPK signaling.
authors.affiliation: Department of Orthopaedics, The Second Affiliated Hospital of Nantong University, Nantong 226001, Jiangsu, PR China.|Department of Orthopaedics, Jinling Hospital, Nanjing Medical University, Nanjing 210008, Jiangsu, PR China.
authors.forename: Jian-Bo
authors.initials: JB
authors.lastname: Fan
authors.affiliation: Department of Orthopaedics, The Second Affiliated Hospital of Nantong University, Nantong 226001, Jiangsu, PR China.
authors.forename: Wei
authors.initials: W
authors.lastname: Liu
authors.affiliation: Department of Orthopaedics, The Second Affiliated Hospital of Nantong University, Nantong 226001, Jiangsu, PR China.
authors.forename: Xin-Hui
authors.initials: XH
authors.lastname: Zhu
authors.affiliation: Department of Orthopaedics, The Second Affiliated Hospital of Nantong University, Nantong 226001, Jiangsu, PR China.
authors.forename: Hong
authors.initials: H
authors.lastname: Yi
authors.affiliation: Department of Orthopaedics, The Second Affiliated Hospital of Nantong University, Nantong 226001, Jiangsu, PR China.
authors.forename: Sheng-Yu
authors.initials: SY
authors.lastname: Cui
authors.affiliation: Department of Orthopaedics, Jinling Hospital, Nanjing Medical University, Nanjing 210008, Jiangsu, PR China.
authors.forename: Jian-Ning
authors.initials: JN
authors.lastname: Zhao
authors.affiliation: Department of Orthopaedics, The Second Affiliated Hospital of Nantong University, Nantong 226001, Jiangsu, PR China.
authors.forename: Zhi-Ming
authors.initials: ZM
authors.lastname: Cui
mesh_terms: D017209:Apoptosis / Q000187:drug effects; D002460:Cell Line; D003907:Dexamethasone / Q000494:pharmacology*; D005786:Gene Expression Regulation; D020868:Gene Silencing; D006801:Humans; D020935:MAP Kinase Signaling System / Q000187:drug effects*; D035683:MicroRNAs / Q000235:genetics*; D010006:Osteoblasts / Q000187:drug effects* / Q000378:metabolism*; D010020:Osteonecrosis / Q000235:genetics / Q000378:metabolism; D011493:Protein Kinase C / Q000235:genetics*; D034622:RNA Interference; D017382:Reactive Oxygen Species / Q000378:metabolism; D000099221:Protein Kinase C zeta
chemical_list: D003907:Dexamethasone; D035683:MicroRNAs; D011493:Protein Kinase C; D017382:Reactive Oxygen Species; D000099221:Protein Kinase C zeta; C543351:MIRN25 microRNA, human
keywords: AMP-activated protein kinase (AMPK); PKCζ; dexamethasone; microRNA-25; osteoblastic cells