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Mutations in Topoisomerase IIbeta result in B cell immunodeficiency

拓扑异构酶 IIbeta 突变导致 B 细胞免疫缺陷

基本信息

批准号：
10786524
负责人：
Lori Broderick
金额：
$ 39.5万
依托单位：
UNIVERSITY OF CALIFORNIA, SAN DIEGO
依托单位国家：
美国
项目类别：
财政年份：
2023
资助国家：
美国
起止时间：
2023-03-17 至 2024-02-29
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/10786524
关键词：
Affect Antibody Diversity B cell differentiation B-Cell Development B-Lymphocytes Binding Bioinformatics Cell Compartmentation Cell physiology Cells Chromatin Loop Chromosomal Rearrangement Chromosome abnormality Collaborations Collection Communities Critical Pathways DNA DNA Binding Domain DNA Double Strand Break DNA Repair DNA Repair Gene DNA biosynthesis Data Defect Development Disease Dominant-Negative Mutation Enzymes Essential Genes Failure Generations Genes Genetic Transcription Genetically Engineered Mouse Genomics Heterozygote Human Immune Immunoglobulin Class Switching Immunoglobulin Switch Recombination Immunologic Deficiency Syndromes Immunologics Immunology Impairment In Vitro Infection Inherited Investigation Knock-in Knowledge Lead Link Lymphoid Mediating Metabolic Modeling Molecular Mus Mutant Strains Mice Mutate Mutation Nonhomologous DNA End Joining Pathway interactions Patients Pattern Play Proteins Relaxation Reporting Research Personnel Role Saccharomyces cerevisiae Scientist Single-Gene Defect Site Stem Cell Development Stress Syndrome System T cell regulation T-Cell Activation T-Cell Development Testing Topoisomerase Topoisomerase II Transcription Process V(D)J Recombination autoreactivity autosome body system central tolerance congenital immunodeficiency experimental study functional disability homologous recombination human disease in vivo induced pluripotent stem cell innovation loss of function mutation malformation mouse model mutant negative affect novel prevent progenitor recruit repaired seal stem cell model therapeutic target

项目摘要

Project Summary/Abstract The study of rare immunodeficiency patients has been extremely instructive to our understanding of B cell development and human disease, revealing mechanisms of B cell development, central tolerance and protection from infection. Syndromic immunodeficiencies, in which the physical malformations are often more pronounced than the underlying immunologic defects, are less frequently studied and less well understood. We recently discovered that mutations in TOP2B underlie the autosomal dominant syndromic B cell immunodeficiency (Hoffman syndrome). Topoisomerases are essential genes required for relaxation of topological stress during DNA replication and gene transcription, acting to prevent the generation of free DNA breaks. We recently reported the first description of a role for TOP2B in a monogenetic human disease, and revealed that heterozygous, dominant negative mutations in the DNA-binding domain of TOP2B led to negative effects on development and function of B cells, while T cell activation was not affected. In this New Investigator proposal, we take a bold, multi-species approach using novel S. cerevisiae models, innovative genetically engineered mice developed by our group, the largest collection of TOP2B mutations in patients with TOP2b mediated immunodeficiency, as well as newly developed patient- derived induced pluripotent stem cells (iPSCs) to explore our hypotheses in an otherwise unobtainable human system. The central hypothesis is that loss of enzymatic function leads to erroneous gene transcription, limited V(D)J recombination, and subsequently the failure of normal B cell differentiation and function. Three specific aims are proposed to test this hypothesis. Specific Aim 1 will determine how mutations in TOP2B generate B cell immunodeficiency through malfunction in the ability to create and re- seal double strand breaks. In vitro and in vivo experiments will examine how patient-associated mutations in TOP2B lead to impaired homologous recombination and non-homologous end joining, disrupting early B cell development. Studies of genomic interactions will examine how mutant Top2b impacts chromatin loop extrusion and impairs fundamental mechanisms of V(D)J recombination and class switching. Specific Aim 2 will determine how mutations in TOP2B impact the recruitment of repair proteins to sites of double strand breaks, leading to reduced break repair, and resulting in reduced efficacy of nonhomologous end joining. Finally, Specific Aim 3 will delineate how Top2b enzymatic function modulates B cell development. Using our distinctive murine models including knock-in and conditional murine models, and iPSCs, we have a unique opportunity to understand the molecular mechanisms underlying this B cell immunodeficiency.

项目总结/文摘