Cellular determinants of cardiopharyngeal multipotency and early fate choices

摘要 普遍的先天性疾病，包括Di George/22q11DS、Noonan和相关综合征，与 心脏缺陷和颅面畸形。22q11缺失综合征源于同名 导致TBX1单倍性功能不全的缺失，而Noonan和相关综合征是影响 Ras-MAPK信号通路。然而，了解心颅面联合的病因 缺陷需要对基因功能的细胞和发育背景有深入的了解。在早期羊水中 胚胎、第二心区(SHF)和分支/咽头肌来自共同的 心咽中胚层中的多能祖细胞种群。TBX1是中的思想功能 心咽祖细胞，控制咽肌发生和SHF发育，并与 成纤维细胞生长因子-MAPK在心脏发育过程中的信号转导，强调了 在早期心咽发育的细胞背景下研究TBX1和成纤维细胞生长因子MAPK信号。 被囊状脊索骨是研究早期心咽的一种简单而强大的脊索状模型 发展，具有高空间和时间分辨率。在Ciona，四个多功能心咽部 祖细胞经历刻板的迁移和细胞分裂，产生不同的第一和第二心脏，以及 部署与脊椎动物保守的基因网络的咽肌谱系。利用独特的 Ciona系统的优点，以及使用特定于谱系的扰动进行的大量先前工作，包括 CRISPR/Cas9介导的突变、定量成像和多重单细胞基因组学方法， 这一建议将首先探索建立空间格局。拟议的工作将解决如何 动态的心咽生态位有助于极化MAPK信号和TBX1/10激活；内在的 有丝分裂纺锤体定位的决定因素，RhoGAP Depdc1，帮助祖细胞通过 关注生态位，分析MAPK信号与MAPK信号通路拮抗的分子基础 早期心脏计划。其次，这项提议将探索潜在的时间动力学之间的过渡 心咽状态，通过研究从头基因表达和命运选择是如何与细胞耦合的 分裂，以及成熟祖细胞转录组的变化如何决定 心咽前体细胞形成心脏和咽肌前体细胞。完成这一雄心勃勃的计划 该提案将对心血管领域具有广泛意义的新兴概念产生深远的见解 发育和干细胞生物学。

SUMMARY Prevalent congenital diseases, including the Di George/22q11DS, Noonan and related syndromes, present with both cardiac defects and craniofacial dysmorphism. The 22q11 Deletion Syndrome arises from eponymous deletions that cause TBX1 haploinsufficiency, while Noonan and related syndromes are RASopathies that affect the RAS-MAPK signaling pathway. However, understanding the etiology of combined cardio-craniofacial defects requires insights into the cellular and developmental contexts of gene function. In early amniote embryos, the second heart field (SHF) and branchiomeric/pharyngeal head muscles emerge from a common population of multipotent progenitors in the cardiopharyngeal mesoderm. TBX1 is thought function in cardiopharyngeal progenitors, to control both pharyngeal myogenesis and SHF development, and interact with Fibroblast Growth Factor (FGF)-MAPK signaling during heart development, highlighting the importance of studying Tbx1 and FGF-MAPK signaling in the cellular context of early cardiopharyngeal development. The tunicate Ciona emerged as a simple and powerful chordate model to study early cardiopharyngeal development, with high spatial and temporal resolution. In Ciona, four multipotent cardiopharyngeal progenitors undergo stereotyped migration and cell divisions, producing distinct first and second cardiac, and pharyngeal muscle lineages that deploy gene networks conserved with vertebrates. Leveraging the unique strengths of the Ciona system, and extensive previous work using lineage-specific perturbations, including CRISPR/Cas9-mediated mutagenesis, quantitative imaging, and multiplexed single cell genomics methods, this proposal will first explore the establishment of spatial patterns. The proposed work will address how a dynamic cardiopharyngeal niche helps polarize MAPK signaling and Tbx1/10 activation; how an intrinsic determinant of mitotic spindle positioning, the RhoGAP Depdc1, helps progenitors orient their divisions with regards to the niche, and analyze the molecular basis for the antagonism between MAPK signaling and the early heart program. Second, this proposal will explore the temporal dynamics underlying transitions between cardiopharyngeal states, by studying how de novo gene expression and fate choices are coupled with cell divisions, and how transcriptome changes in maturing progenitors determine the competence of cardiopharyngeal progenitors to form heart and pharyngeal muscle precursors. Completion of this ambitious proposal will yield far-reaching insights into emerging concepts of broad significance for cardiovascular developmental and stem cell biology.