Investigation of fmnl2 in cerebellar development

fmnl2 在小脑发育中的研究

• 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
• 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' 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

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.

项目摘要 先天性共济失调通常是由于小脑的功能障碍和畸形引起的，尤其是 内侧vermis。这些疾病可能是由于缺乏适当的发育信号级联而引起的 决定神经元的增殖和形成。原发性纤毛为各种发育信号传导提供了枢纽 蛋白质（例如SHH或Wnt）。睫状蛋白功能障碍导致影响人类的罕见遗传疾病 神经系统，光学系统以及肝脏，肾脏和骨骼系统的发展。患者 像乔伯特综合征和相关疾病这样的纤毛病显示小脑vermis垂体性发育不全，上的增厚 小脑子花梗和一个加深的骨窝。细胞骨架的成分，例如肌动蛋白 和微管，在纤毛生成和现有睫状成分和维持中起着至关重要的作用 支撑脚手架。尽管已经发现许多与纤毛相关的基因是这些疾病的因果 formin家族的细胞骨架调节剂及其与纤毛的关系尚未完全定义，也没有 这些分子以前与脑发育异常有关。 我们的实验室使用一种前瞻性遗传方法来识别对小脑发育至关重要的途径 该大脑区域的神经元。通过化学诱变筛选，我们发现了一种共同的小鼠 表型的突变体类似于某些纤毛病中观察到的突变体：小脑海马发育不全， 异常叶面，沿前后轴的小脑伸长，以及上轴的失败 小脑花梗进行十二次。通过位置克隆，我们在FMNL2中的剪接受体上确定了一个突变， 导致外显子跳过FMNL2成绩单。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 通过该外显子，对于该蛋白质的稳定性是必需的。 FMNL2是一种自身抑制的细胞骨架效应子，以前已证明可以驱动肌动蛋白聚合在 培养细胞的丝状和薄片尖端。尽管该家族中的其他蛋白质已显示为结合和 调节微管，肌动蛋白和影响纤毛形成，该蛋白在微管中的作用和 大脑发育过程中的肌动蛋白尚不清楚。使用这种新型鼠标模型，我将研究FMNL2的作用 在肌动蛋白和微管稳定中 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。