Molecular mechanisms of Hedgehog receptor function

Hedgehog受体功能的分子机制

基本信息

批准号：
8350531
负责人：
PHILIP A BEACHY
金额：
$ 29.83万
依托单位：
STANFORD UNIVERSITY
依托单位国家：
美国
项目类别：
财政年份：
2012
资助国家：
美国
起止时间：
2012-08-15 至 2016-03-31
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/8350531
关键词：
Accounting Address Adult Affect Affinity Binding Biochemical Biological Assay C-terminal Cell Line Cell membrane Cell model Chemical Structure Chlamydomonas Cilia Congenital Abnormality Coupling Development Disease Drosophila genus Embryo Erinaceidae Event Family Family member Flagella Fractionation Genetic Genetic Transcription Human Insecta Integral Membrane Protein Ion Channel Ions Lead Lifting Light Link Lipids Malignant Neoplasms Mammalian Cell Mammals Maps Mass Spectrum Analysis Measures Mediating Mediator of activation protein Membrane Methods Microscopy Molecular Molecular Models Mus Mutation Natural regeneration Neoplasms Organ Pathway interactions Pattern Phenotype Physiology Plants Platyhelminths Play Protein Family Proteins Protons Reagent Regulation Resistance Role Screening procedure Series Signal Transduction Signaling Protein Source Specific qualifier value Teratogens Testing Therapeutic Tissues Transmembrane Transport Xenopus oocyte Yeasts base ciliopathy cyclopamine extracellular hedgehog signal transduction human SMO protein light effects member molecular modeling receptor receptor function response small molecule smoothened signaling pathway tissue regeneration trafficking

项目摘要

DESCRIPTION (provided by applicant): The Hedgehog (Hh) signaling pathway plays a central role in specifying the embryonic patterning of metazoan organs. Post-embryonically, Hh signaling mediates homeostatic regeneration of adult tissues and is associated with numerous cancers when inappropriately active. Despite its importance in development, physiology, and disease we fundamentally do not understand how the extracellular Hedgehog signal is transduced across the membrane. The central question is the mechanism by which the Hh receptor Patched (Ptc; Ptch1 in mammals), a transporter-like protein, acts to regulate Smoothened (Smo), a member of the seven transmembrane protein family. From flatworms to insects to mammals, Ptc inhibits Smo activity in the absence of Hh, and thisinhibition is lifted upon Hh binding to Ptc and its co-receptors, thu releasing Smo for pathway activation through a series of downstream events and consequent changes in gene transcription. Mechanistically, Ptch1 is thought to act as a proton-dependent transmembrane transporter of a lipidic modulator of Smo activity across the membrane, but this modulator remains to be identified. In addition, mammalian Hh signal transduction has been linked to the primary cilium, but the actual role of the primary cilium in transduction is not understood. To elucidate the molecular and cellular mechanisms of Hh receptor function in the cilium we propose to define intrinsic sequence requirements and cellular factors required for Ptch1/Smo ciliary trafficking and signal transduction, focusing in particular on signals and factors that are regulated by Hh pathway activity. We will identify endogenous small molecules that mediate Ptch1 regulation of Smo activity, having initially identified Chlamydomonas flagella as an enriched source of such a modulatory lipid. We will test whether Ptch1 functions as a transmembrane transporter that depends on a chemiosmotic gradient and investigate the effects of Ptch1 function on the dynamics of Smo ciliary trafficking. Our findings will be integrated into a detailed cellular and molecular account of Hh signal transduction, and may provide a basis for improvements in therapies for Hh pathway-dependent cancers. PUBLIC HEALTH RELEVANCE: We propose a multi-disciplinary approach to address the question of how presence of the extracellular Hedgehog protein signal is transmitted across the cell membrane by the Patched and Smoothened components. Our findings will illuminate the causes of and possible therapies for birth defects and neoplastic growth associated with derangements of Hedgehog pathway regulation and activity.

描述（由申请人提供）： Hedgehog (Hh) 信号通路在指定后生动物器官的胚胎模式中发挥着核心作用。胚胎后，Hh 信号传导介导成体组织的稳态再生，并且当活动不当时与多种癌症相关。尽管它在发育、生理学和疾病中很重要，但我们从根本上不了解细胞外 Hedgehog 信号是如何跨膜转导的。核心问题是 Hh 受体 Patched（Ptc；哺乳动物中的 Ptch1）（一种转运蛋白样蛋白）调节 Smoothened（Smo）（七跨膜蛋白家族成员）的机制。从扁虫到昆虫再到哺乳动物，Ptc 在 Hh 不存在的情况下抑制 Smo 活性，并且这种抑制在 Hh 与 Ptc 及其共受体结合后解除，从而通过一系列下游事件和随后的基因转录变化释放 Smo 来激活通路。从机制上讲，Ptch1 被认为是 Smo 跨膜活性脂质调节剂的质子依赖性跨膜转运蛋白，但这种调节剂仍有待鉴定。此外，哺乳动物的Hh信号转导与初级纤毛有关，但初级纤毛在转导中的实际作用尚不清楚。为了阐明纤毛中 Hh 受体功能的分子和细胞机制，我们建议定义 Ptch1/Smo 纤毛运输和信号转导所需的内在序列要求和细胞因子，特别关注受 Hh 通路活性调节的信号和因子。我们将鉴定介导 Ptch1 对 Smo 活性调节的内源性小分子，初步确定衣藻鞭毛是这种调节脂质的丰富来源。我们将测试 Ptch1 是否作为依赖于化学渗透梯度的跨膜转运蛋白发挥作用，并研究 Ptch1 功能对 Smo 纤毛运输动力学的影响。我们的研究结果将被整合到 Hh 信号转导的详细细胞和分子解释中，并可能为改进 Hh 通路依赖性癌症的治疗提供基础。公共卫生相关性：我们提出了一种多学科方法来解决细胞外 Hedgehog 蛋白信号如何通过修补和平滑组件跨细胞膜传输的问题。我们的研究结果将阐明与 Hedgehog 通路调节和活性紊乱相关的出生缺陷和肿瘤生长的原因和可能的治疗方法。