Characterizing Mammalian Embryonic polyA Binding Protein

描述（由申请人提供）：为了使候选人在发育生物学和分子遗传学方面获得必要的教学和科学培训，并使他能够在学术生殖内分泌学方面发展事业，重点是卵母细胞和早期胚胎发育的分子生物学以及相关的生殖疾病，特提交此申请临床科学家发展奖。阐明配子体发生和早期胚胎发生过程中基因表达调控的分子机制，可能对理解和治疗卵母细胞老化、非整倍体和胚胎丢失等生殖问题具有重要意义。在本申请中，候选人提出研究哺乳动物多a结合蛋白（PABP）及其在卵母细胞和早期胚胎发育过程中调控基因表达的作用。卵母细胞成熟与转录抑制有关。成熟卵母细胞和早期胚胎直至合子转录激活的基因表达受母源mrna的翻译激活和抑制调控。储存的母体mrna的翻译激活的第一步是polyA尾部的细胞质延伸。下一步是将掩膜- elf4e络合物解离，从而形成翻译必需的elF4E-elF4G络合物。这两个过程都在爪蟾卵母细胞中得到了深入的研究。在那里，去除掩蔽需要细胞质聚腺苷化和PABP。虽然细胞质PABP （PABP1）早已被发现，但它在卵母细胞和早期胚胎中并不表达。该候选人最近在非洲爪蟾中发现了一种卵母细胞和胚胎特异性PABP，命名为ePAB。ePAB作为爪蟾早期发育过程中的主要PABP和deadenylation抑制剂，很可能调控polyA尾长和母体mrna的揭膜/翻译。基于爪蟾和小鼠在调控胞质聚腺苷化的分子机制上的相似性，该候选人假设哺乳动物存在ePAB，并确定了一个假定的小鼠ePAB同源物。在这项应用中，他的目的是通过确定其时间和组织特异性表达模式来证实最初的发现，并进一步表征其在细胞质聚腺苷化中的功能，特别是在加工性和尾长控制方面。随后，候选人将创建ePAB敲除小鼠。申请K08导师奖，是为了使候选人在发育生物学和分子遗传学方面获得必要的教学和科学培训，并使他能够在生殖内分泌学学术领域发展事业，重点研究卵母细胞和早期胚胎发育的分子生物学以及相关的生殖疾病。

DESCRIPTION (provided by applicant): This application for the Mentored Clinical Scientist Development Award is submitted so as to enable the candidate to gain necessary didactic and scientific training in developmental biology and molecular genetics, and to enable him to develop a career in academic reproductive endocrinology with a focus on molecular biology of oocyte and early embryo development as well as associated reproductive disorders. Elucidation of molecular mechanisms regulating gene expression during gametogenesis and early embryogenesis may have important implications for the understanding and treatment of reproductive problems such as oocyte aging, aneuploidy, and embryo loss. In this application, the candidate proposes to investigate a mammalian polyA binding protein (PABP) and its role in the regulation of gene expression during oocyte and early embryo development. Oocyte maturation is associated with suppression of transcription. Gene expression in mature oocyte and early embryo until the activation of zygotic transcription is regulated by translational activation and repression of maternally derived mRNAs. The first step in translational activation of stored maternal mRNAs is cytoplasmic extension of the polyA tail. A subsequent step is dissociation of the maskin-elF4E complex, so that the translationally essential elF4E-elF4G complex can form. Both of these processes have been intensively studied in the Xenopus oocyte. There, unmasking requires both cytoplasmic polyadenylation and a PABP. Although a cytoplasmic PABP (PABP1) has long been known, it is not expressed in oocytes and early embryos. The candidate has recently identified an oocyte and embryo-specific PABP in Xenopus named ePAB. As the predominant PABP during Xenopus early development and an inhibitor of deadenylation, ePAB most likely regulates polyA tail length and unmasking/translation of maternal mRNAs. Based on similarities between Xenopus and mouse in the molecular mechanisms regulating the control of cytoplasmic polyadenylation, the candidate hypothesized that a mammalian ePAB exists, and he identified a putative mouse ePAB ortholog. In this application, he aims to confirm the initial findings by determining its time- and tissue-specific expression pattern, and to further characterize its function in cytoplasmic polyadenylation, specifically in processivity and tail length control. Subsequently, the candidate will create an ePAB knock-out mouse. This application for the mentored grant K08 award is submitted so as to enable the candidate to gain necessary didactic and scientific training in developmental biology and molecular genetics, and to enable him to develop a career in academic Reproductive Endocrinology with a focus on molecular biology of oocyte and early embryo development and associated reproductive disorders.