Mechanistic links between mutations in the CLPB gene and congenital neutropenia

项目总结/摘要 CLPB基因的遗传性双等位基因突变是先天性中性粒细胞减少症的原因 与MEGCANN相关，这是一种罕见的常染色体隐性遗传病（OMIM条目#616271）。在其 严重的形式，这种疾病导致死亡的几个月的年龄，由于显着的神经系统疾病， 症状或危及生命的感染。最近发现的新生单等位基因突变， CLPB基因以显性负性方式作用，也可引起严重的先天性中性粒细胞减少症。 CLPB基因编码一种广泛表达的线粒体蛋白，含有几个锚蛋白 重复序列和单个AAA+（与多种细胞活动相关的ATP酶）模块。的 中性粒细胞前体细胞中CLPB功能的分子机制尚不清楚， 突变CLPB变体引起的线粒体缺陷及其与缺陷性粒细胞生成的联系 定义不明确。我们假设CLPB是糖酵解代谢转变的关键 在中性粒细胞分化过程中的线粒体呼吸。我们将通过以下方式检验这一假设： 实现两个具体目标。在目的1中，我们将确定CLPB在线粒体中的作用， 形态学、代谢和中性粒细胞分化，使用成髓细胞系模型， 粒细胞生成。本目标将检验CLPB在以下方面发挥重要作用的子假设： 在中性粒细胞分化过程中的线粒体重塑和代谢重编程。在Aim中 2，我们将研究疾病突变对CLPB和关键蛋白之间相互作用的影响。 线粒体动力学和嵴形态的调节因子。这一目标将测试子- 双等位基因与单等位基因突变效应之间的主要差异 对CLPB活性的影响来自突变的CLPB变体的不同相互作用倾向。 在结果中，我们的研究将为CLPB在中性粒细胞中的作用提供新的见解 分化，将有助于了解疾病CLPB变体的分子缺陷，并将 为开发CLPB突变引起的血小板减少症的潜在治疗方法奠定了基础。

PROJECT SUMMARY/ABSTRACT Hereditary biallelic mutations in the CLPB gene are the cause of congenital neutropenia associated with MEGCANN, a rare autosomal recessive disease (OMIM entry #616271). In its severe form, the disease leads to death by a few months of age as a result of significant neurologic symptoms or life-threatening infections. Recently identified de novo monoallelic mutations in the CLPB gene act in a dominant-negative manner and also cause severe congenital neutropenia. The CLPB gene encodes a broadly expressed mitochondrial protein containing several ankyrin repeats and a single AAA+ (ATPases Associated with diverse cellular Activities) module. The molecular mechanism of CLPB function in neutrophil precursor cells is not known, and the mitochondrial defects elicited by mutated CLPB variants and their link to defective granulopoiesis are poorly defined. We hypothesize that CLPB is essential for the metabolic shift from glycolysis to mitochondrial respiration during neutrophil differentiation. We will test this hypothesis by completing two Specific Aims. In Aim 1, we will determine the role of CLPB in mitochondrial morphology, metabolism, and neutrophil differentiation using myeloblastic cell line models of granulopoiesis. This Aim will test the sub-hypothesis that CLPB plays an essential role in mitochondrial remodeling and metabolic reprogramming during neutrophil differentiation. In Aim 2, we will examine the effect of disease mutations on the interactions between CLPB and key regulators of mitochondrial dynamics and cristae morphology. This Aim will test the sub- hypothesis that the principal difference between the effects of biallelic vs. monoallelic mutations on the CLPB activity arises from distinct interaction propensities of the mutated CLPB variants. At the outcome, our studies will provide a new insight into the role of CLPB in neutrophil differentiation, will help understand the molecular defects of the disease CLPB variants, and will set the stage for developing potential treatments for neutropenias caused by CLPB mutations.