Regulation of Zebrasfish Development by Semaphorin-Olfactomedin 2 Interactions

描述（由申请人提供）：信号素通路在轴突引导中的作用已经被很好地表征。此外，最近的研究结果强调了该途径在其他关键领域的重要作用，如血管生成、血管生成、细胞迁移/分化、免疫调节和癌症病理。Pi的实验室最近发现了斑马鱼的嗅觉蛋白2 (OM2)，这是一种分泌的糖蛋白，具有高度保守的嗅觉蛋白结构域。初步的表达和功能表征研究表明，OM2在三个重要的发育过程中发挥作用：轴突引导、神经嵴迁移/分化和血管生成。对OM2突变体的表型与已发表的信号蛋白通路中断的表型进行比较分析，一致地使PI提出以下总体假设：OM2通过与信号蛋白通路的相互作用调节轴突引导、神经嵴细胞迁移/分化和血管生成。为了测试om2信号通路在这些过程中的联系，提出了三个特定的目的。特异性目的1：验证OM2变异体中高度特异性的颅轴突引导缺陷是由于OM2和信号蛋白受体复合物之间的直接相互作用受到干扰的假设。具体目的2：验证OM2突变体中咽软骨缺失是由于颅神经嵴细胞（cNCC）迁移和/或分化受到干扰的假设，而颅神经嵴细胞的迁移和/或分化严重依赖于信号蛋白通路。特异性目的3：验证OM2变异体中仅在迟发性颅血管中发现的高度特异性缺陷是由于信号素-神经匹林和/或vegf -神经匹林通路的干扰所致的假设。

DESCRIPTION (provided by applicant): Semaphorin pathways have been well characterized for their roles in axon guidance. Moreover, recent findings highlight significant roles of this pathway in other critical areas such as vasculogenesis, angiogenesis, cell migration/differentiation, immune regulation, and cancer pathology. The Pi's laboratory has recently identified zebra fish olfactomedin 2 (OM2), a secreted glycoprotein with a highly conserved olfactomedin domain. Initial expression and functional characterization studies revealed OM2's roles in three important developmental processes: axon guidance, neural crest migration/differentiation, and angiogenesis. Analyses on phenotypes of OM2 morphants in comparison with published phenotypes from disrupted semaphorin pathways, consistently led the PI to formulate the following overall hypothesis: OM2 regulates axon guidance, neural crest cell migration/differentiation, and angiogenesis via its interaction with the semaphorin pathway. In order to test the OM2-semaphorin pathway link in these processes, three Specific Aims are proposed. Specific Aim 1: To test the hypothesis that highly specific cranial axon guidance defects in OM2 morphants are due to the perturbation of direct interaction between OM2 and semaphorin receptor complexes. Specific Aim 2: To test the hypothesis that the absence of pharyngeal cartilages in OM2 morphants is due to the perturbation of cranial neural crest cell (cNCC) migration and/or differentiation, which is critically dependent upon semaphorin pathways. Specific Aim 3: To test the hypothesis that highly specific defects found only in late-onset cranial vasculature in OM2 morphants are due to perturbation in semaphorin-neuropilin and/or VEGF-neuropilin pathways. These hypotheses will be tested by (1) high resolution expression analysis of OM2 and semaphorin signaling molecules, deficiency of which results in highly similar phenotypes as OM2-deficiency phenotypes; (2) concomitant inhibition of semaphorin components and OM2 to verify functional convergence of OM2 in the semaphorin signaling pathway; (3) testing direct molecular interactions between OM2 and components of the semaphorin receptor complex. Given that the semaphorin pathway is known to be critically involved in adult nerve regeneration, craniofacial malformation (most frequent human birth defects), and tumor angiogenesis, novel insights into the regulation of this signaling pathway will be of paramount health benefit.