The Proregion of Mouse BMP15 Regulates the Cooperative Interactions of BMP15 and GDF9
The Proregion of Mouse BMP15 Regulates the Cooperative Interactions of BMP15 and GDF9
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DOI：
10.1095/biolreprod.108.068163
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发表时间：
2008-11-01
影响因子：
3.6
通讯作者：
Juengel, Jennifer L.
中科院分区：
文献类型：
--
作者：
McIntosh, C. Joy;Lun, Stan;Juengel, Jennifer L.
骨形态发生蛋白15(BMP15)和生长分化因子9(GDF9)由哺乳动物卵母细胞分泌，是卵泡发育、排卵和生育所必需的。然而，BMP15和GDF9蛋白的分泌形式以及BMP15和GDF9之间的协同分子相互作用的性质还没有得到充分的研究。在本研究中，我们发现重组小鼠BMP15和GDF9以裂解的成熟蛋白和前区蛋白的形式分泌，BMP15也以未裂解的成熟蛋白的形式分泌。每种生长因子的成熟蛋白和前区域蛋白之间存在非共价相互作用。此外，GDF9成熟蛋白被发现与BMP15前区域免疫共沉淀，提示BMP15和GDF9之间存在异构体关联。小鼠GDF9主要以成熟蛋白二聚体的形式存在，在BMP15存在和不存在的情况下都是如此。相反，当BMP15与GDF9结合时，主要形成前区域和成熟蛋白的多聚体，为异构体相互作用提供了进一步的证据。在大鼠颗粒细胞胸苷掺入生物实验中，小鼠BMP15与GDF9协同作用，并通过BMPR2和ACVR1B/TGFBR1/ACVR1C受体介导的信号通路发挥作用。用GDF9成熟蛋白抗体进行的免疫中和实验表明，这些协同作用具有物种特异性。此外，与前区域抗体的免疫中和强调了BMP15前区域参与BMP15/GDF9的合作相互作用。综上所述，这些发现支持一个新的假说，即重组小鼠BMP15和GDF9的细胞外协同作用是多聚体的，涉及BMP15的前区域，并且很可能是物种特异性的。
Bone morphogenetic protein 15 (BMP15) and growth and differentiation factor 9 (GDF9) are secreted by the mammalian oocyte and are essential for ovarian follicular development, ovulation, and fertility. However, the secreted forms of the BMP15 and GDF9 proteins and the nature of cooperative molecular interactions between BMP15 and GDF9 previously reported have not been fully characterized. In this study, we found that recombinant mouse BMP15 and GDF9 are secreted as cleaved mature and proregion proteins, with BMP15 also secreted as uncleaved promature protein. Noncovalent interactions were identified between the mature and proregion proteins of each growth factor. Moreover, GDF9 mature protein was found to coimmunoprecipitate with the BMP15 proregion, suggestive of a heteromeric association between BMP15 and GDF9. Mouse GDF9 was found to exist mostly as a dimer of mature protein, in both the presence and absence of BMP15. In contrast, BMP15 formed mostly multimers of proregion and mature protein when combined with GDF9, providing further evidence for heteromeric interaction. Mouse BMP15 was found to act cooperatively with GDF9 in a rat granulosa cell thymidine incorporation bioassay and to signal through the BMPR2 and ACVR1B/TGFBR1/ACVR1C receptor-mediated pathways. Immunoneutralization experiments using GDF9 mature protein antibody indicated that these cooperative interactions are species specific. Additionally, immunoneutralization with proregion antibodies highlighted the involvement of the BMP15 proregion in BMP15/GDF9 cooperative interactions. Taken together, these findings support a novel hypothesis where the extracellular cooperative interactions of recombinant mouse BMP15 and GDF9 are multimeric, involving the proregion of BMP15, and may well be species specific.