维生素D缺乏是一个世界性的健康问题，可直接影响骨骼的生长发育。在前期研究中，我们发现维生素D受体（VDR）基因敲除胎鼠的股骨皮质面积明显小于野生型胎鼠，在VDR基因敲除鼠的原代骨细胞中发现miR-140表达明显低于野生型鼠，表明VDR可能通过miR-140调控骨骼发育。因此，本课题将根据VDR介导的细胞通路，通过体内外实验验证VDR是否与miR-140存在结合位点、PKC、MAPK通路是否参与miR-140表达的调控，明确VDR通过miR-140及其下游靶基因SP1、Smad3调控骨发育的分子机制，同时利用羊膜腔和皮下注射等方法上调miR-140在胎鼠体内的表达，观察对VDR敲除鼠的治疗效果，探索miR-140转基因治疗维生素D缺乏导致骨发育异常的最佳方法和治疗时间点，对预防和治疗胎儿骨骼畸形提供理论依据。

Recent evidence has indicated a reemergence of vitamin D-deficient rickets and an alarming prevalence of vitamin D insufficiency worldwide and it is well known that vitamin D status is related to musculoskeletal health. In previous study, we observed decreased femoral cortical area in vitamin D receptor (VDR) null fetuses compared with wild type control. Expression of miR-140 was downregulated in primary cultured bone cells from VDR null mice, indicating that VDR might regulate skeleton development through miR-140. In this project, we intend to investigate whether VDR interact with promoter region of miR-140, and whether its regulation is mediated through PKC or MAPK pathway, so that to clarify the mechanism of VDR and miR-140、target genes regulation on bone development. Furthermore we would treat VDR null mice with intraamniotic administration and subcutaneous injection of miR-140 and to explore the best treatment strategy and timepoint of miRNA administration on treatment of vitamin D deficiency. Our study might contribute to prevetion and treatment of fetal skeleton malformation.