Development of Zebrafish Enteric Nervous System and Intestinal Smooth Muscle

描述（申请人提供）：肠神经系统在肠的正常功能中起着至关重要的作用。肠神经元提供运动和感觉信息，以产生推进运动和维持器官稳态。肠神经元起源于神经嵴细胞，迁移到消化系统的吻端，进入外间质，并迁移到尾端。在此过程中，肠道前体增殖并分化为神经元和神经胶质，从而支配整个器官。巨结肠病证明了肠内神经支配的关键性。这种消化系统疾病发生在5000个活产儿中，并导致人类结肠的神经节段。神经节肠段的长度因多种导致疾病的遗传异常而变化。负责肠神经元发育的基因在包括斑马鱼在内的多种脊椎动物物种中都是高度保守的。遗传保守与脊椎动物消化系统结构和功能的保守相结合，使得斑马鱼等动物模型成为研究肠道和平滑肌发育遗传学的有效模型。我们将使用斑马鱼来确定肠道前体迁移和分化以及平滑肌发育的其他遗传成分。先前的研究已经确定，肠道神经元的发育使用了在其他模型系统中发现的同源途径。特异性目的1将确定野生型肠增殖模式和神经元亚型分化。特异性目的2验证了zFKBP/SMAP和BMP信号的斑马鱼同源性对肠道和肠道平滑肌的发育至关重要的假设。特异性目的3验证了消化突变体flotte latte（flo）和slimjim （slj）的肠道和肠道平滑肌缺陷部分归因于已确定的同源信号通路的假设。这些实验将使我们更全面地了解肠道和平滑肌发育的遗传学以及Hirschprung病的组成部分。

DESCRIPTION (provided by applicant): The enteric nervous system plays a critical role in normal function of the intestine. Enteric neurons provide motor and sensory information to generate propulsive movement and maintain organ homeostasis. Enteric neurons originate from neural crest cells, migrate to the rostral portion of the digestive system, enter the outer mesenchyme, and migrate to the caudal end. Along the way, the enteric precursors proliferate and differentiate into neurons and glia thereby innervating the entire organ. The critical nature of enteric neuron innervation of the intestine is demonstrated by Hirschsprung's disease. This digestive disease occurs in 1 in 5000 live births and results in aganglionic segments of the human colon. The length of aganglionic intestinal segments varies due to multiple genetic abnormalities that give rise to the disease. Genes responsible for development of the enteric neurons are strongly conserved across multiple vertebrate species, including zebrafish. Genetic conservation combined with conservation of structure and function of the vertebrate digestive system makes animal models like zebrafish an effective model to study the genetics of enteric and smooth muscle development. We will use zebrafish to determine additional genetic components underlying migration and differentiation of enteric precursors and development of smooth muscle. Previous investigations have determined that enteric neurons develop using homologous pathways that have been identified in other model systems. Specific aim1 will identify the wild type pattern of enteric proliferation and neuronal subtype differentiation. Specific aim 2 tests the hypothesis that the zebrafish homologue of zFKBP/SMAP and BMP signaling are critical for development of enteric and intestinal smooth muscle. Specific aim 3 tests the hypothesis that the enteric and intestinal smooth muscle defects in digestive mutants flotte latte(flo) and slimjim (slj) are due in part to identified homologous signaling pathways. These experiments will lead to a more complete understanding of the genetics of enteric and smooth muscle development and the components that underlie Hirschprung's disease.