Division of Endocrinology and Centre for Research in Anabolic Skeletal Targets in Health and Illness (ASTHI), CSIR-Central Drug Research Institute, B.S. 10/1, Sector-10, Jankipuram Extension, Lucknow, India.
J Mol Med (Berl). 2018 May;96(5):427-444. doi: 10.1007/s00109-018-1624-y. Epub 2018 Mar 9.
We report the role of miR-1187 in regulation of osteoblast functions. Over-expression of miR-1187 inhibited osteoblast differentiation. Target prediction analysis tools and experimental validation by luciferase 3' UTR reporter assay identified BMPR-II and ArhGEF-9 as direct targets of miR-1187. ArhGEF-9 activates Cdc42 which has a major role in actin reorganization. BMP-2 also induces actin polymerization. Role of miR-1187 in actin reorganization was determined by western blotting, immunofluorescence, and in vivo gene silencing studies. Reduced protein levels of BMPR-II, activated Cdc42, and downstream signaling molecules were observed in miR-1187-transfected osteoblasts. miR-1187 over-expression resulted in decreased actin polymerization. Additionally, P-cofilin, which does not bind F-actin, was decreased in miR-1187-transfected cells. These results were corroborated by administration of BMPR-II exogenously in miR-1187-transfected osteoblasts. Silencing of miR-1187 in neonatal mice mitigated all the inhibitory effects of miR-1187 on actin cytoskeletal rearrangement. Importantly, in vivo treatment of miR-1187 inhibitor to ovariectomized BALB/c mice led to significant improvement in trabecular bone microarchitecture. Overall, miR-1187 functions as a negative regulator of osteogenesis by repressing BMPR-II and ArhGEF-9 expression thus suppressing non-Smad BMP2/Cdc42 signaling pathway and inhibiting actin reorganization. miR-1187 functions as a negative regulator of osteogenesis by repressing BMPR-II expression, which in turn, suppresses non-Smad BMP2/Cdc42 signaling pathway, thus inhibiting actin cytoskeletal rearrangement. Silencing of miR-1187 significantly improves trabecular bone microarchitecture. As miR-1187 exerts a negative regulatory role in osteoblasts function, hence, we propose that therapeutic approaches targeting miR-1187 could be useful in enhancing the bone formation and treatment of pathological conditions of bone loss.
我们报告了 miR-1187 在调节成骨细胞功能中的作用。miR-1187 的过表达抑制了成骨细胞分化。靶预测分析工具和荧光素酶 3'UTR 报告分析实验鉴定出 BMPR-II 和 ArhGEF-9 是 miR-1187 的直接靶标。ArhGEF-9 激活 Cdc42，Cdc42 在肌动蛋白重排中起主要作用。BMP-2 也诱导肌动蛋白聚合。通过 Western blot、免疫荧光和体内基因沉默研究确定了 miR-1187 在肌动蛋白重排中的作用。在转染 miR-1187 的成骨细胞中观察到 BMPR-II 蛋白水平降低，Cdc42 激活和下游信号分子激活。miR-1187 过表达导致肌动蛋白聚合减少。此外，在转染 miR-1187 的细胞中，不结合 F-肌动蛋白的 P-丝切蛋白减少。这些结果在转染 miR-1187 的成骨细胞中添加外源性 BMPR-II 时得到了证实。在新生小鼠中沉默 miR-1187 减轻了 miR-1187 对肌动蛋白细胞骨架重排的所有抑制作用。重要的是，体内给予 miR-1187 抑制剂治疗去卵巢 BALB/c 小鼠可显著改善小梁骨微结构。总的来说，miR-1187 通过抑制 BMPR-II 和 ArhGEF-9 的表达来抑制成骨作用，从而抑制非 Smad BMP2/Cdc42 信号通路并抑制肌动蛋白重排。miR-1187 通过抑制 BMPR-II 的表达来抑制成骨作用，从而抑制非 Smad BMP2/Cdc42 信号通路，抑制肌动蛋白细胞骨架重排。沉默 miR-1187 可显著改善小梁骨微结构。由于 miR-1187 在成骨细胞功能中发挥负调控作用，因此，我们提出针对 miR-1187 的治疗方法可能有助于增强骨形成和治疗骨丢失的病理状况。
