Cellular determinants of cardiopharyngeal multipotency and early fate choices

总结 常见的先天性疾病，包括Di乔治/22 q11 DS、努南综合征和相关综合征， 心脏缺陷和颅面畸形22 q11缺失综合征是由癫痫引起的。 导致TBX 1单倍不足的缺失，而努南综合征和相关综合征是影响 RAS-MAPK信号通路。然而，了解心颅面联合畸形的病因， 缺陷需要深入了解基因功能的细胞和发育背景。在早期， 胚胎，第二心脏领域（SHF）和branchiomeric/咽头肌出现从一个共同的 心咽中胚层中的多能祖细胞群体。TBX 1被认为在 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（FGF）-心脏发育过程中的MAPK信号传导，强调了 研究Tbx 1和FGF-MAPK信号在早期心咽发育的细胞背景下。 被囊玻璃海鞘作为一种简单而强大的脊索动物模型出现，以研究早期心咽 发展，具有很高的空间和时间分辨率。在玻璃海鞘中， 祖细胞经历定型迁移和细胞分裂，产生不同的第一和第二心脏，并且 咽肌谱系，部署与脊椎动物保守的基因网络。利用独特的 Ciona系统的优势，以及以前使用特定谱系扰动的广泛工作，包括 CRISPR/Cas9介导的诱变、定量成像和多重单细胞基因组学方法， 这项建议将首先探讨建立空间格局。拟议的工作将解决如何 动态心咽生态位有助于抑制MAPK信号传导和Tbx 1/10激活; 有丝分裂纺锤体定位的决定因素RhoGAP Depdc 1帮助祖细胞定向分裂， 并分析MAPK信号通路与细胞凋亡之间拮抗作用的分子基础。 早期心脏计划第二，本提案将探讨时间动力学之间的过渡 cardiopharyngeal状态，通过研究从头基因表达和命运选择如何与细胞 分裂，以及成熟祖细胞中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。完成这一雄心勃勃的 该提案将对心血管疾病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.