Investigation of fmnl2 in cerebellar development

fmnl2 在小脑发育中的研究

基本信息

批准号：
10641755
负责人：
Joyce Tran
金额：
$ 4.14万
依托单位：
UNIVERSITY OF CALIFORNIA, SAN DIEGO
依托单位国家：
美国
项目类别：
财政年份：
2022
资助国家：
美国
起止时间：
2022-06-02 至 2026-06-01
项目状态：
未结题

来源：
https://reporter.nih.gov/project-details/10641755
关键词：
3&apos Splice Site Actins Affect Alleles Anterior Ataxia Axon Behavior Binding Brain Brain Diseases Brain region Candidate Disease Gene Cell surface Cells Cerebellar Diseases Cerebellar malformation Cerebellar vermis structure Cerebellum Chemicals Cilia Cilium Microtubule Cognitive deficits Complement Critical Pathways Cultured Cells Cytoskeleton Data Defect Development Developmental Delay Disorders Disease Exons FMNL2 gene Failure Family Filopodia Fossa Functional disorder Genes Hippocampus Human Human Development Induced Mutation Investigation Joubert syndrome Kidney Knockout Mice Laboratory Finding Length Link Liver Maintenance Medial Microtubule Stabilization Microtubules Molecular Morphology Motor Mus Mutagenesis Mutant Strains Mice Mutation Nerve Degeneration Nervous System Neurodevelopmental Disorder Neurologic Neurons Optics Patients Phenotype Play Point Mutation Polymers Proliferating Protein Family Proteins RNA Splicing Regulation Role SHH gene Sequence Analysis Signal Transduction Signaling Protein Skeletal system Structure System Transcript base brain abnormalities cancer cell cell type ciliopathy cilium biogenesis conditional knockout exon skipping experimental study forward genetics functional status genetic approach granule cell human disease in vivo insight kinetosome malformation migration mouse model mutant nerve stem cell novel polymerization positional cloning protein function rare genetic disorder scaffold screening social deficits trafficking

项目摘要

PROJECT SUMMARY Congenital ataxias generally result from dysfunctions and malformations of the cerebellum, particularly the medial vermis. These disorders may result from the lack of proper developmental signaling cascades which dictate the proliferation and formation of neurons. Primary cilia provide a hub for various developmental signaling proteins such as SHH or WNT. Dysfunction in ciliary proteins leads to rare genetic disorders affecting human development in the nervous system, optical system, and liver, kidney, and skeletal systems. Patients with ciliopathies like Joubert Syndrome and related disorders display cerebellar vermis hypoplasia, thickened superior cerebellar peduncles, and a deepened interpeduncular fossa. Components of the cytoskeleton, such as actin and microtubules, play a vital role in ciliogenesis and the maintenance of existing ciliary components and supporting scaffold. Although many cilia-related genes have been found to be causal for these disorders, cytoskeletal regulators of the formin family and their relationship with cilia has not yet been fully defined, nor have these molecules been previously associated with abnormal brain development. Our lab uses a forward genetic approach to identify pathways critical to cerebellar development and degeneration of neurons in this brain region. Through a chemical mutagenesis screening, we discovered an ataxic mouse mutant with phenotypes similar to those observed in some ciliopathies: cerebellar hippocampal hypoplasia, abnormal foliation, cerebellar elongation along the anterior-posterior axis, as well as the failure of the superior cerebellar peduncle to decussate. By positional cloning, we identified a mutation at a splice acceptor in Fmnl2, leading to exon skipping in Fmnl2 transcripts. Interestingly, levels of Fmnl2 transcripts in the brain of mutant mice are unchanged compared to WT, but protein levels are reduced, suggesting that the in-frame deletion encoded by this exon are necessary for stability of this protein. FMNL2 is an autoinhibited cytoskeletal effector that has been previously shown to drive actin polymerization at filopodia and lamellipodia tips of cultured cells. Although other proteins in this family have shown to bind and regulate microtubules, actin, and influence cilia formation, whether this protein functions in microtubules and actin during brain development is unknown. Using this novel mouse model, I will investigate the role of FMNL2 in actin and microtubule stabilization and determine how the hypomorphic loss of this protein may impact ciliogenesis and cilia maintenance. These studies will enlighten our understanding of cerebellar malformations and impact our understanding of the mechanisms underlying the role of microtubules and actin in human ciliopathies.

项目概要先天性共济失调通常是由小脑功能障碍和畸形引起的，特别是小脑内侧蚓部。这些疾病可能是由于缺乏适当的发育信号级联而导致的决定神经元的增殖和形成。初级纤毛为各种发育信号提供中心蛋白质，例如 SHH 或 WNT。纤毛蛋白功能障碍导致影响人类的罕见遗传性疾病神经系统、视觉系统、肝、肾和骨骼系统的发育。患者患有纤毛病，如朱伯特综合征和相关疾病，表现为小脑蚓部发育不全、上肢增厚小脑脚和加深的脚间窝。细胞骨架的成分，例如肌动蛋白和微管，在纤毛发生和现有纤毛成分的维护中发挥着至关重要的作用支撑脚手架。尽管许多纤毛相关基因被发现与这些疾病有关，福明家族的细胞骨架调节因子及其与纤毛的关系尚未完全确定，也未完全确定。这些分子以前是否与大脑发育异常有关？我们的实验室使用正向遗传方法来识别对小脑发育和退化至关重要的途径该大脑区域的神经元。通过化学诱变筛选，我们发现了共济失调小鼠具有与某些纤毛病中观察到的表型相似的突变体：小脑海马发育不全，异常的叶状结构、小脑沿前后轴的伸长以及上脑的衰竭小脑脚交叉。通过定位克隆，我们鉴定了 Fmnl2 剪接受体处的突变，导致 Fmnl2 转录本中的外显子跳跃。有趣的是，突变小鼠大脑中 Fmnl2 转录物的水平与 WT 相比没有变化，但蛋白质水平降低，表明框内缺失编码该外显子对于该蛋白质的稳定性是必要的。 FMNL2 是一种自抑制细胞骨架效应器，之前已被证明可以驱动肌动蛋白聚合培养细胞的丝状伪足和片状伪足尖端。尽管该家族中的其他蛋白质已被证明可以结合并调节微管、肌动蛋白并影响纤毛形成，无论该蛋白是否在微管中发挥作用，大脑发育过程中的肌动蛋白尚不清楚。使用这种新颖的小鼠模型，我将研究 FMNL2 的作用肌动蛋白和微管稳定性，并确定该蛋白质的亚形性丢失如何影响纤毛发生和纤毛维持。这些研究将启发我们对小脑畸形的理解并影响我们对微管和肌动蛋白在人类中作用的机制的理解纤毛病。