MicroRNA-25 targets PKC? 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 ? (PKC?). Results show that microRNA-25-5p (miR-25-5p) targets PKC?'s 3' untranslated regions (UTRs). Forced-expression of miR-25 downregulated PKC? 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 PKC? and inhibited AMPK activation, exacerbating Dex damages. Notably, PKC? shRNA knockdown similarly activated AMPK and protected osteoblastic cells from Dex. AMPK activation was required for miR-25-induced osteoblastic cell protection. AMPK? 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 AMPK? knockdown or mutation. Significantly, miR-25-5p level was increased in patients' necrotic femoral head tissues, which was correlated with PKC? downregulation and AMPK hyper-activation. These results suggest that miR-25-5p targets PKC? and protects osteoblastic cells from Dex possibly via activating AMPK signaling.

SUBMITTER: Fan JB 

PROVIDER: S-EPMC5356877 | biostudies-other | 2017 Jan

REPOSITORIES: biostudies-other