人源LGR4受体识别RSPO1配体的结构机制研究

发布时间：2018-01-08 13:20

本文关键词：人源LGR4受体识别RSPO1配体的结构机制研究　出处：《浙江大学》2017年博士论文　论文类型：学位论文

【摘要】：Wnt信号通路在胚胎发育以及成体组织更新等许多生理过程中发挥重要的作用。当Wnt信号通路在生殖细胞阶段发生突变时会导致遗传病的发生,而在体细胞中发生突变时则会导致肠癌以及其他相关疾病。R-spondin蛋白(简称RSPOs)是一组能够和Wnt蛋白一起协同刺激Wnt/β-catenin信号通路从而在发育以及组织更新等生理过程中发挥重要作用的糖蛋白。最近,孤儿受体LGR4以及它的同源蛋白被证实能够作为R-spondin蛋白的受体从而介导R-spondin对Wnt信号通路的激活。LGR4-6属于B型LGR受体,其特征除了经典的七次跨膜区域外,还包括细胞外和R-spondin蛋白结合的包含leucine-rich repeat(LRR)重复序列的结构域。尽管R-spondin和LGR蛋白具有非常重要生理功能,但是LGRs识别R-spondins的分子机理却依然没有得到很好的解释。在我们的这项研究中,我们采用了 leucine-rich repeat杂交技术获得了活性良好、性质均一的LGR415以及LGR49重组蛋白,并且成功地解析了单个LGR415以及LGR49/RSPO1复合物的晶体结构。结构表明LGR4胞外结构域呈扭曲的马蹄状结构,而RSPO1的CRD结构域以一种平坦的β样构象结合在LGR4的内表面,它们之间存在许多的亲水以及疏水作用。我们还注意到LGR4上和RSPO1作用的氨基酸在LGR4/5/6上都是保守的,推测LGR4/5/6应该以相同的界面结合R-spondin蛋白。综合先前其它小组解析的LGR5结构我们推测LGR4/5/6都是仅采用单独的内表面来结合R-spondins,表明B型LGR受体结合配体的模式是单位点结合,这和A型LGR受体(LGR1/2/3)的两步识别步骤以及C型LGR受体(LGR7/8)的多界面结合模式是有显著区别的。总之,我们的工作以及先前别人解析的结构很好地解释了 LGR受体超家族识别配体多样性的机制。
[Abstract]:Wnt signaling pathway plays an important role in many physiological processes, such as embryonic development and adult tissue renewal. When the Wnt signaling pathway is mutated in germ cells, it will lead to genetic diseases. Mutations in somatic cells can lead to bowel cancer and other related diseases. R-spondin protein (RSPOsS). It is a group of glycoproteins that can co-stimulate WNT / 尾 -catenin signaling pathway with Wnt protein to play an important role in physiological processes such as development and tissue renewal. Orphan receptor LGR4 and its homologous protein have been proved to be able to act as R-spondin receptor to mediate R-spondin activation of Wnt signaling pathway. LGR4-6 belongs to. Type B LGR receptor. In addition to the classical seven-times transmembrane region. Also included are extracellular and R-spondin protein-binding containing leucine-rich repeaters (LRRRs). Repeat sequence domain. Although R-spondin and LGR proteins have very important physiological functions. But the molecular mechanism of LGRs recognition of R-spondins is still not well explained. LGR415 and LGR49 recombinant proteins with good activity and homogeneity were obtained by leucine-rich repeat hybridization. The crystal structures of single LGR415 and LGR49/RSPO1 complexes were successfully elucidated. The results showed that the extracellular domain of LGR4 was a twisted horseshoe structure. The CRD domain of RSPO1 binds to the inner surface of LGR4 in a flat 尾-like conformation. There are many hydrophilic and hydrophobic interactions between them. We also note that amino acids on LGR4 and RSPO1 are conserved on LGR4/5/6. We conjectured that LGR4/5/6 should bind R-spondin protein with the same interface. We conjectured that the LGR4/5/6 only uses a single inner structure, taking into account the LGR5 structures that were previously explained by other groups. Surface bound to R-spondins. The pattern of B type LGR receptor binding ligand is unit point binding. This is significantly different from the two-step recognition process of type A LGR receptor LGR1 / 2 / 3 and the multi-interface binding pattern of type C LGR receptor LGR7 / 8. Our work and previous structures well explain the mechanism of LGR receptor superfamily recognition of ligand diversity.
【学位授予单位】：浙江大学
【学位级别】：博士
【学位授予年份】：2017
【分类号】：Q51

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