The role of the endogenous retroviral family, IAP, in placentation.

内源性逆转录病毒家族 IAP 在胎盘形成中的作用。

• 批准号: 10577407
• 负责人: Julie C Baker
• 金额: $ 25.3万
• 依托单位: STANFORD UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2022
• 资助国家: 美国
• 起止时间: 2022-09-22 至 2027-07-31
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10577407
• 关键词: ATAC-seq; Alpha Particles; Binding; Binding Proteins; Biology; Cell membrane; Cells; Clustered Regularly Interspaced Short Palindromic Repeats; Communication; Data; Decidua; Decidual Cell; Defect; Elements; Embryo; Embryology; Endogenous Retroviruses; Evolution; Family; Frequencies; Gene Expression Regulation; Generations; Genome; Genomics; Goals; Human; Immunity; Investigation; Knock-out; Length; Location; Maternal Behavior; Maternal-Fetal Exchange; Mediating; Mothers; Mus; Mutagens; Mutation; Pattern; Placenta; Placentation; Pregnancy; Protein Family; Proteins; RNA; Regulation; Regulator Genes; Regulatory Element; Reporter; Research; Retrotransposition; Role; Signal Transduction; Somatic Mutation; Source; Testing; Tissues; Transcript; Transgenes; Viral; Viral Physiology; Viral Proteins; base; bisulfite sequencing; blastocyst; cell growth regulation; extracellular; extracellular vesicles; fetal; gag Gene Products; genetic approach; imprint; in vivo; insight; knock-down; myometrium; particle; protein function; small hairpin RNA; trophoblast stem cell; wound healing

ABSTRACT Endogenous retroviruses (ERVs) constitute 10% of all genomes, yet they remain the wild west of biology, even though they function within the host cell in a myriad of critical ways, including as regulatory elements, as extracellular messengers, as sources of viral-like particles (VLPs), and, importantly, as somatic mutagens. Our overreaching goal is to understand how the ERV family, IAP (Intracisternal type A Protein), functions at the mouse maternal-fetal interface. Thousands of genomic IAP instances exist that consist of gag, pro, pol sequences flanked by LTRs. These instances have lost the ancestral envelope (env) sequence and form naked VLPs that remain inside the cell and can transpose. Today, only a single copy, IAPE-D1, remains with a conserved envelope (env) sequence that mediates extracellular release of its VLPs. This strong evolutionary conservation of the env in IAPE-D1 suggests that it serves an important extracellular function. Thus, IAPs function in two distinct cellular domains: one as an extracellular messenger, and the other as an intracellular source of regulation and mutation. The rigor of prior research strongly supports this hypothesis. More than 50 years ago VLPs were described in placentas of all species, including mouse and human. The source of the mouse VLPs is likely IAP as we find that it is the only ERV family expressed during placentation. Our data suggests that these VLPs are functional as, when we knock down IAP using shRNA in trophoblast stem cells (TSCs) or in mouse embryos, we observe defects in differentiation and placentation. Further, we find that IAP binds specific RNAs in TSCs, including those that mediate differentiation and imprinting, suggesting that IAP VLPs contain cargo. Importantly, we find that IAP protein is expressed in maternal tissues in the absence of transcript, suggesting that it was transported from the neighboring placental cells. Based on our own preliminary results and more than 50 years of prior research on IAP, we hypothesize that 1) the only extracellular IAP, IAPE-D1, is forming VLPs in the mouse placenta that transport specific RNAs into the maternal decidua and 2) the intracellular IAPs serve multiple functions including the generation of naked VLPs that are mutagenic and as sequences that serve as critical regulatory elements within the placenta genome. While human placentas do not have IAP, they do have HERVK, which forms VLPs that are likely to serve similar functions especially given that the placenta is a hotspot for convergent evolution. Overall, this proposal will deliver the function and mechanism of a major fraction of the unexplored genome during pregnancy.

抽象的 内源性逆转录病毒 (ERV) 占所有基因组的 10%，但它们仍然是人类基因组的狂野西部。 生物学，尽管它们在宿主细胞内以多种关键方式发挥作用，包括作为调节 元素，作为细胞外信使，作为病毒样颗粒（VLP）的来源，并且重要的是作为体细胞 诱变剂。我们的首要目标是了解 ERV 家族、IAP（脑池内 A 型蛋白）如何 在小鼠母胎界面上发挥作用。存在数千个基因组 IAP 实例，其中包括堵嘴、 pro、pol 序列两侧为 LTR。这些实例丢失了祖先信封（env）序列并且 形成裸露的 VLP，保留在细胞内并可以转座。如今，只剩下一个副本 IAPE-D1 具有介导 VLP 胞外释放的保守包膜 (env) 序列。这个强 IAPE-D1 中 env 的进化保守性表明它具有重要的细胞外功能。 因此，IAP 在两个不同的细胞域中发挥作用：一个作为细胞外信使，另一个作为细胞域。 细胞内调节和突变的来源。 先前研究的严谨性有力地支持了这一假设。 50多年前，VLP 在所有物种的胎盘中都有描述，包括小鼠和人类。小鼠VLP的来源可能是IAP 因为我们发现它是胎盘期间唯一表达的 ERV 家族。我们的数据表明这些 VLP 其功能是，当我们在滋养层干细胞 (TSC) 或小鼠胚胎中使用 shRNA 敲除 IAP 时， 我们观察到分化和胎盘的缺陷。此外，我们发现 IAP 结合 TSC 中的特定 RNA， 包括那些介导分化和印记的，表明 IAP VLP 含有货物。 重要的是，我们发现 IAP 蛋白在没有转录本的情况下在母体组织中表达，这表明 它是从邻近的胎盘细胞转运而来的。基于我们自己的初步结果及更多信息 经过 50 年的 IAP 研究，我们假设 1) 唯一的细胞外 IAP，IAPE-D1，正在形成 小鼠胎盘中的 VLP 将特定 RNA 转运至母体蜕膜和 2) 细胞内 IAP 具有多种功能，包括产生具有诱变性和序列的裸 VLP 作为胎盘基因组内的关键调控元件。虽然人类胎盘没有 IAP， 他们确实有 HERVK，它形成的 VLP 可能具有类似的功能，特别是考虑到 胎盘是趋同进化的热点。总体而言，该提案将实现功能和机制 怀孕期间未探索的基因组的主要部分。