Biological Mechanism of INF2-mediated FSGS

INF2介导的FSGS的生物学机制

• 批准号: 8517110
• 负责人: MARTIN R. POLLAK
• 金额: $ 39.66万
• 依托单位: BETH ISRAEL DEACONESS MEDICAL CENTER
• 依托单位国家: 美国
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-07-15 至 2014-11-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8517110
• 关键词: Actins; Alleles; Amino Acids; Binding; Biochemical; Biological; C-terminal; Cell physiology; Cells; Defect; Disease; Endoplasmic Reticulum; Engineering; Exons; Family; Family member; Focal Segmental Glomerulosclerosis; Genes; Glomerular Filtration Rate; Histologic; Human; Inherited; Injury; Kidney; Kidney Diseases; Kidney Failure; Lead; Mediating; Microfilaments; Microtubules; Modeling; Monomeric GTP-Binding Proteins; Mus; Mutate; Mutation; N-terminal; Pattern; Phenotype; Physiology; Point Mutation; Proteins; Proteinuria; RNA Splicing; Renal function; Role; Structure; Subgroup; Testing; Variant; base; depolymerization; formin-2; gain of function; glomerular function; human disease; in vivo; in vivo Model; loss of function; member; mouse model; mutant mouse model; podocyte; polymerization; public health relevance; research study; rho

DESCRIPTION (provided by applicant): We have identified a new gene which when mutated leads to a form of progressive kidney disease characterized by proteinuria, reduced glomerular filtration rate, and a histologic pattern of injury characterized by focal and segmental glomerulosclerosis (FSGS). This gene, INF2 (for Inverted Formin 2), is a member of the diaphanous subgroup of the formin family. INF2, like other members of the diaphanous formin subfamily, functions to accelerate actin filament polymerization. Unlike other members, INF2 can also accelerate actin depolymerization. Members of this subfamily of formins are able to autoinhibit their activity by an intramolecular interaction between two domains, the N-terminal DID (diaphanous inhibitory domain) and the C-terminal DAD (diaphanous autoregulatory domain). We have found point mutations in the DID of INF2 in eleven unrelated families with autosomal dominant FSGS. These mutations segregate with disease, are absent from controls, and alter highly conserved amino acids. The mode of inheritance, the absence of clear loss-of-function alleles, and the localization of all of the mutations to the DID, suggest a gain-of-function effect. In this application, we propose experiments to help define the mechanism by which INF2 mutations lead to human disease and to understand the role of INF2 in kidney function. In Aim 1, we propose to explore the effects of INF2 mutations on its biochemical functions. We will examine the hypothesis that FSGS- associated mutations in INF2 disrupt intramolecular interactions leading to functional changes in INF2. We will test the effects of FSGS-causing mutations on INF2 intramolecular interactions (DID with DAD), on the ability of INF2 to mediate actin filament polymerization and depolymerization, and the interactions of INF2 with actin filaments and microtubules. In Aim 2, we will define the effects of INF2 mutations on cellular functions. We will examine the hypothesis that INF2 mutations, by disinhibiting INF2 activity, alter actin- based cell function. We will study the role of INF2 in cells and the effect of INF2 mutations on actin-based structures, on actin dynamics, on the dynamics of the endoplasmic reticulum, and on interacting proteins. In Aim 3, we will develop and analyze two new INF2 mutant mouse models. We will use these models to test the role of INF2 in the podocyte and observe the effects of an INF2 point mutation in an in vivo model. We will engineer a mouse model with a disease-associated INF2 point mutation and also develop a podocyte-specific INF2 deficient mouse. We will examine the effect of INF2 mutation and deficiency on glomerular function in vivo. PUBLIC HEALTH RELEVANCE: We have identified a new focal segmental glomerulosclerosis (FSGS) gene. When mutated, this gene, INF2, causes kidney disease in humans. Better understanding how defects in this gene cause human disease will have significant and direct implications for understanding, and ultimately, treating, common forms of renal failure and renal failure progression.

描述（由申请人提供）：我们已经确定了一种新的基因，该基因突变会导致一种以蛋白尿、肾小球滤过率降低和局灶性和节段性肾小球硬化（FSGS）为特征的进行性肾脏疾病。这个基因，INF2（倒置双Formin 2），是双Formin家族中透明亚群的成员。与其他透明双胍亚家族成员一样，INF2具有加速肌动蛋白丝聚合的功能。与其他成员不同，INF2也可以加速肌动蛋白解聚。该形成蛋白亚家族的成员能够通过两个结构域，n端DID（透明抑制结构域）和c端DAD（透明自调节结构域）之间的分子内相互作用来自动抑制它们的活性。我们在11个不相关的常染色体显性FSGS家族中发现了INF2的DID点突变。这些突变与疾病分离，在对照中不存在，并改变高度保守的氨基酸。遗传模式、缺乏明确的功能丧失等位基因以及所有突变都定位于DID，表明存在功能获得效应。在这项应用中，我们提出了一些实验来帮助确定INF2突变导致人类疾病的机制，并了解INF2在肾功能中的作用。在目的1中，我们拟探讨INF2突变对其生化功能的影响。我们将检验一种假设，即INF2中FSGS相关的突变会破坏分子内相互作用，从而导致INF2的功能改变。我们将测试fsgs引起的突变对INF2分子内相互作用（DID与DAD）的影响，对INF2介导肌动蛋白丝聚合和解聚的能力的影响，以及INF2与肌动蛋白丝和微管的相互作用。在目标2中，我们将定义INF2突变对细胞功能的影响。我们将检验假设，即INF2突变，通过去抑制INF2活性，改变基于肌动蛋白的细胞功能。我们将研究INF2在细胞中的作用，以及INF2突变对肌动蛋白结构、肌动蛋白动力学、内质网动力学和相互作用蛋白的影响。在Aim 3中，我们将开发和分析两种新的INF2突变小鼠模型。我们将使用这些模型来测试INF2在足细胞中的作用，并在体内模型中观察INF2点突变的影响。我们将设计一个带有疾病相关的INF2点突变的小鼠模型，并开发一个足细胞特异性的INF2缺陷小鼠。我们将研究体内INF2突变和缺乏对肾小球功能的影响。