Mechanisms of Impaired Granulopoiesis Due to CLPB Mutations

项目摘要/摘要 这项研究的目的是阐明严重先天性心脏病的分子发病机制。 由酪蛋白溶血肽酶B(ClpB)突变引起的中性粒细胞减少(SCN)。系统性红斑狼疮是一种先天性疾病 粒细胞生成的特点是从出生起就有严重的慢性中性粒细胞减少症，继发于 感染性并发症，并转化为髓系恶性肿瘤。通过对一个大的 SCN队列，候选人最近发现ClpB杂合性错义突变是一种新的 SCN的常见原因。ClpB是一种存在于线粒体内部的核编码蛋白质 在膜空间中，它作为分子伴侣发挥解聚和促进重新折叠的作用 错误折叠的蛋白质。然而，将ClpB功能受损与粒细胞缺陷联系起来的机制 编队情况尚不清楚。在这项提案中，首席调查员将检验突变的ClpB起作用的假设 以一种显性的方式扰乱ClpB的伴侣功能，导致线粒体应激受损 早幼粒细胞的反应和诱导凋亡。为了验证这一假设，以下是具体目标 建议：目的1)确定ClpB突变是否损害线粒体对内质的反应 粒细胞前体细胞中的网织应激；目的2)检查ClpB突变对开关的影响 早期粒细胞前体从糖酵解到氧化磷酸化。 建议的研究应提供对ClpB-的分子病理生理学的理解 突变型SCN。最终，对正常和SCN相关粒细胞生成的更好理解可能会提示新的 治疗或预防慢性肾小球肾炎患者中性粒细胞减少的治疗方法 清髓化疗。 这位内科科学家候选人的长期目标是建立一个富有成效和独立的 一家主要学术机构的实验室，研究正常和恶性造血。主要导师 丹尼尔·林克博士是一位杰出的科学家，也是一位经验丰富、尽职尽责的导师。一组 具有互补的科学和翻译专业知识的高级调查人员将在正式的K99上服务 导师委员会提供科学和职业指导。华盛顿大学是一个例外 培训初级研究人员的环境，特别是那些对造血感兴趣的人。有现成的通道 拥有众多核心设施和强大的智力环境，拥有干细胞生物学、中性粒细胞 生物学、线粒体生物学和造血的细胞模型。除了参加课程外， 生物统计学和生物信息学，应聘者将利用在 华盛顿大学帮助初级调查人员建立和运营一个独立的实验室。华盛顿 大学承诺提供实验室空间和资源，以促进候选人过渡到 独立。

Project Summary/Abstract The goal of the proposed research is to elucidate the molecular pathogenesis of severe congenital neutropenia (SCN) due to mutations of caseinolytic peptidase B (CLPB). SCN is an inborn disorder of granulopoiesis characterized by severe chronic neutropenia from birth, premature death secondary to infectious complications, and transformation to myeloid malignancy. Through exome sequencing of a large SCN cohort, the candidate has recently identified heterozygous missense mutations in CLPB as a new and frequent cause of SCN. CLPB is a nuclear-encoded protein that resides within the inner mitochondrial membrane space where it functions as a molecular chaperone to disaggregate and facilitate re-folding of misfolded proteins. However, the mechanisms linking impaired CLPB function to a defect in granulocyte formation are unclear. In this proposal, the principle investigator will test the hypothesis that mutant CLPB acts in a dominant fashion to disrupt the chaperone function of CLPB, resulting in impaired mitochondrial stress responses and induction of apoptosis in promyelocytes. To test this hypothesis, the following specific aims are proposed: Aim 1) to determine whether CLPB mutations impair the mitochondrial response to endoplasmic reticulum stress in granulocytic precursors; Aim 2) to examine the impact of CLPB mutations on the switch from glycolysis to oxidative phosphorylation in early granulocytic precursors. The proposed studies should provide an understanding of the molecular pathophysiology of CLPB- mutant SCN. Ultimately, a better understanding of normal and SCN-related granulopoiesis may suggest new therapeutic approaches to treat or prevent neutropenia in patients with SCN, and in patients receiving myeloablative chemotherapy. The long-term goal of this physician-scientist candidate is to establish a productive and independent laboratory at a major academic institution studying normal and malignant hematopoiesis. The primary mentor is Dr. Daniel Link, a distinguished scientist who is also an experienced and committed mentor. A panel of senior investigators with complementary scientific and translational expertise will serve on a formal K99 mentorship committee to provide both scientific and career guidance. Washington University is an exceptional environment to train junior investigators, especially those interested in hematopoiesis. There is ready access to numerous core facilities and a strong intellectual environment with experts in stem cell biology, neutrophil biology, mitochondrial biology, and cellular models of hematopoiesis. In addition to taking courses in biostatistics and bioinformatics, the candidate will take advantage of the broad portfolio of workshops offered at Washington University to help junior investigators establish and run an independent laboratory. Washington University has committed to providing laboratory space and resources to facilitate the candidate’s transition to independence.