BMP2/7异二聚体高效诱导成骨的信号通路机制的研究

The bone morphogenetic protein (BMP)-based tissue engineering is one of the hottest research focuses for the treatment of large-volume bone defects. In our previous studies, we found that heterodimeric BMP could induce the in-vitro osteoblastogenesis more rapidly with a lower concentration and a significantly higher dose-efficiency in comparison with homodimeric BMP. Our in-vivo experiment also corroborated that the low-dose heterodimeric BMP2/7 facilitated more rapid bone regeneration and more mature microstructure in peri-implant bone defects than the homodimeric BMPs. However, the signaling pathways and molecular mechanisms responsible for the high efficiency of heterodimeric BMPs remain unveiled. We have already screened the expression of osteogenesis-related mRNA using microarray. In addition, we also put forward with possible molecular mechanisms in the aspects of both extracellular interactions of BMP-ligands-receptor-antagonists and intracellular signaling pathways. In this proposal, we will test our hypotheses using RNA sequencing, microarray, RNA silencing, and pathway inhibitors, etc. We will uncover the signaling pathways of heterodimeric BMP2/7 and identify the molecular mechanisms for its efficient and unique functions in osteogensis. We are also aiming to establish theoretical basis for heterodimeric BMP-based tissue engineering and facilitate its earlier clinical application.

以骨形态发生蛋白（BMP）为基础的骨组织工程是修复大体积骨组织缺损这一重大医学难题的研究热点。本课题组多项研究证实：与BMP同二聚体相比，BMP 异二聚体能够高效诱导体外成骨细胞化生，快速修复体内骨组织缺损，并促进骨微结构的改建和成熟。然而，BMP 异二聚体的信号通路和分子机制尚不明确。我们前期利用microarray技术检测了其信号通路相关基因的表达规律，并从细胞外配体-受体-拮抗剂的相互作用和细胞内信号通路两大方面提出了可能的分子机制。在本项目中，课题组拟采用表面等离子共振技术、RNA测序(RNA-Seq)、microarray、RNA干扰、信号通路抑制剂等细胞及分子生物学技术来验证我们的假设,进而阐明其信号通路转导机制,揭示BMP异二聚体高效诱导成骨的分子机制。为有效构建以BMP异二聚体为基础的组织工程化骨提供理论依据，促进其早期实现临床转化。

以骨形态发生蛋白（BMP）等细胞因子为基础的骨组织工程是修复大体积骨缺损这一重大医学难题的研究热点之一。本课题组前期研究发现：与BMP同二聚体相比，BMP 异二聚体在体外诱导成骨具有起效早、剂量低，作用快等优点。体内试验也证实：极低剂量BMP 异二聚体能够快速修复骨缺损，促进骨微结构的改建和成熟。此外, BMP 异二聚体在胚胎发育和抗肿瘤方面也显示出独特的作用。然而，BMP 异二聚体的信号转导和分子机制罕见报道。但BMP2/7异二聚体这一作用特点的信号机制尚不明确。故本研究分别选取成骨细胞系（小鼠前体成骨细胞）、原代骨髓间充质干细胞，分别检测了BMP2/7异二聚体、BMP2同二聚体及BMP7同二聚体诱导成骨分化及其内在机制及在细胞外拮抗剂作用下，三种骨形态发生蛋白与受体结合情况；进一步引入细胞成骨分化抑制剂ATRA，从而检测BMP2/7在成骨分化抑制剂作用下的诱导成骨效果及其机制。此外项目组引入破骨前体细胞系，检测BMP2/7异二聚体、BMP2同二聚体及BMP7同二聚体在有/无ATRA作用下诱导破骨分化的相关指标，并引入RAR受体抑制剂，最终评价三种骨形态发生蛋白诱导破骨分化的效果，揭示其内在机制，为有效构建以BMP异二聚体为基础组织工程化骨提供理论依据，促进其早期实现临床转化，修复大体积骨缺损。