Mechanistic links between mutations in the CLPB gene and congenital neutropenia

项目摘要/摘要 遗传性ClpB基因双等位基因突变是先天性中性粒细胞减少症的原因 与巨细胞遗传病有关的是一种罕见的常染色体隐性遗传病(OMIM条目#616271)。在ITS中 由于严重的神经系统疾病，这种疾病会导致几个月大的婴儿死亡。 症状或危及生命的感染。最近发现了新的单等位基因突变 ClpB基因以显性-负性方式起作用，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，含有几个强链蛋白 重复和单个AAA(与不同细胞活动相关的ATPase)模块。这个 ClpB在中性粒细胞前体细胞中发挥作用的分子机制尚不清楚，而且 ClpB突变引起的线粒体缺陷及其与粒细胞生成缺陷的关系 是定义不清的。我们假设ClpB对于糖酵解的代谢转变是必不可少的。 在中性粒细胞分化过程中对线粒体呼吸的影响。我们将通过以下方式验证这一假设 完成两个具体目标。在目标1中，我们将确定ClpB在线粒体中的作用 小鼠成髓细胞系模型的形态、代谢和中性粒细胞分化 粒细胞生成。这一目标将检验ClpB在其中发挥关键作用的子假说 中性粒细胞分化过程中线粒体重塑和代谢重编程。在AIM 2，我们将研究疾病突变对ClpB和KEY之间相互作用的影响 线粒体动力学和嵴形态的调节器。这一目标将考验潜艇-- 假设双等位基因突变和单等位基因突变的影响之间的主要差异 在ClpB上，活性源于突变的ClpB变体的不同相互作用倾向。 在这一结果中，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 为开发针对ClpB突变引起的中性粒细胞减少症的潜在治疗方法奠定基础。

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.