Cellular and Molecular Analysis of the Role of Inositol in Neurulation

描述(申请人提供)：神经管缺陷(NTD)是人类最常见的出生缺陷之一，仅脊柱裂的发生率为千分之一。鉴于NTDS的高频率，一个重要的研究领域一直是预防方法。在许多情况下，母体补充叶酸可以预防NTDS。然而，大约30%的NTDS对这种膳食补充剂没有反应，目前还没有针对这些缺陷的治疗方法。越来越多的证据表明，补充肌醇可以帮助预防叶酸耐药性NTDS，目前正在进行一项临床试验来测试这一可能性。我们的长期目标是了解肌醇在神经形成过程中如何发挥其保护作用。这项建议的目的是以斑马鱼为模型系统，研究肌醇代谢促进神经收敛延伸(CE)的可能机制，CE是神经形成的早期和必要阶段。我们将解决一般假设，即肌醇1，3，4，5，6-五磷酸2-激酶(IPK1)，产生肌醇六磷酸(IP6)，与纤毛蛋白Ift88相互作用，介导极化的细胞运动，驱动神经CE。在目标1中，我们将研究Ift88在神经CE中的作用机制。我们的工作假设是，Ift88形成细胞质微管(MTs)，我们知道这是极化细胞运动所必需的。这一假说将通过检查Ift88缺失胚胎中MT网络的完整性来检验。在目标2中，我们将确定Ipk1是否通过以Ift88依赖的方式调节MT来促进神经CE。通过比较在Ipk1、Ift88和Ipk1；Ift88双突变体中观察到的表型，并测试中心体对Ipk1的需求，可以实现这一研究目标。这项工作将增加我们对Ift88和Ipk1功能的理解，揭示神经管形成的基本机制，并为肌醇保护作用的模型提供基础。

DESCRIPTION (provided by applicant): Neural tube defects (NTDs) are among the most frequent birth defects in humans, with a frequency of 1/1000 for spinal bifida alone. Given the high frequency of NTDs, an important area of research focus has been on preventative methods. In many cases NTDs can be prevented by maternal supplementation with folic acid. Nevertheless, around 30% of NTDs are unresponsive to this dietary supplement and there is currently no therapy available for these defects. Increasing evidence suggests that inositol supplementation can help prevent folate-resistant NTDs and a clinical trial is currently underway to test this possibility. Our long-term objective is to understand how inositol exerts its protectve effect during neurulation. The goal of this proposal is to investigate a putative mechanism by which inositol metabolism promotes neural convergence extension (CE), an early and essential stage of neurulation, using zebrafish as a model system. We will address the general hypothesis that Inositol 1,3,4,5,6-pentakisphosphate 2-kinase (Ipk1), the kinase that generates inositol hexakisphosphate (IP6), interacts with the ciliary protein Ift88 to mediate the polarized cell movements that drive neural CE. In Aim 1 we will investigate the mechanism by which Ift88 functions in neural CE. Our working hypothesis is that Ift88 nucleates cytoplasmic microtubules (MTs), which we know to be required for polarized cell movement. This hypothesis will be tested by examining the integrity of the MT network in Ift88-depleted embryos. In Aim 2 we will determine if Ipk1 promotes neural CE by regulating MTs in an Ift88-dependent manner. This research goal will be achieved by comparing the phenotypes observed in Ipk1, Ift88 and Ipk1; Ift88 double mutants and testing the requirement for Ipk1 in the centrosome, the organelle that nucleates MTs. The proposed work should increase our understanding of the function of Ift88 and Ipk1, reveal essential mechanisms underlying neural tube formation and provide the basis for a model on the protective effect of inositol.