Functional Consequences of Ubiquitin Depletion During B Lymphocyte Differentiation

B 淋巴细胞分化过程中泛素耗竭的功能后果

• 批准号: 10459410
• 负责人: Giada Bianchi
• 金额: $ 20.73万
• 依托单位: BRIGHAM AND WOMEN'S HOSPITAL
• 依托单位国家: 美国
• 财政年份: 2020
• 资助国家: 美国
• 起止时间: 2020-08-13 至 2025-07-31
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10459410
• 关键词: Apoptosis; B cell differentiation; B lymphoid malignancy; B-Lymphocytes; Biological Markers; Biology; Bone Marrow; Cancer Biology; Cancerous; Cell Death; Cell Survival; Cells; Cellular biology; Cessation of life; Clustered Regularly Interspaced Short Palindromic Repeats; DNA; DNA Damage; DNA Repair; DNA Sequence Alteration; DNA analysis; Data; Development; Disease; Educational workshop; Generations; Genetic; Genomic Instability; Goals; Heavy-Chain Immunoglobulins; Hematologic Neoplasms; Immunoglobulins; Impairment; Innovative Therapy; International; Investigation; Knock-out; Knowledge; Life; Link; Malignant - descriptor; Malignant Neoplasms; Mass Spectrum Analysis; Mediating; Mentors; Modeling; Molecular; Monoclonal gammopathy of uncertain significance; Multiple Myeloma; Mutation; Nuclear; Oncogenic; Oncology; Outcome; Pathogenesis; Pathologic; Physiological; Plant Roots; Plasma Cells; Precancerous Conditions; Proliferating; Proteins; Proteomics; Public Health; Publishing; Research; Research Personnel; Rest; Secondary to; Stress; Structure of germinal center of lymph node; Technology; Testing; Tetracyclines; Time; Transfection; Transgenic Mice; Tumor Suppressor Genes; UBC gene; Ubiquitin; Western Blotting; Western World; Work; base; career; design; driver mutation; experimental study; innovation; knock-down; meetings; molecular targeted therapies; mouse model; multicatalytic endopeptidase complex; novel; novel therapeutics; plasma cell differentiation; protein degradation; proteotoxicity; response; small hairpin RNA

Project Summary/Abstract Multiple myeloma (MM) is an incurable cancer of terminally differentiated plasma cells (PC), characterized by abundant immunoglobulin (Ig) synthesis. Most PC are short lived and die only a few days after differentiation through unclear molecular mechanisms. MM pathogenesis also remain elusive with no single genetic driver mutation, but pervasive DNA damage. We have previously shown increased cargo of polyubiquitinated (polyUb) proteins and decreased proteasome activity in differentiating B lymphocytes and we hypothesized proteotoxicity as driver of PC death. By using absolute mass spectrometry (AQUA) to quantify ubiquitin (Ub) in the same B cell differentiation model, our preliminary data show that 60% free Ub depletion occurs in PC compared to resting B cells, concomitantly with maximal Ig secretion and apoptosis. Second, we discovered that cells surviving long term post differentiation can be identified and display markers of ongoing DNA damage. As Ub is necessary for proper DNA damage response (DDR), polyUb protein degradation and DDR compete for the same Ub pool. Based on our work, we propose a unifying model for short-lived PC death and MM pathogenesis centered on critical Ub depletion. Our core hypothesis is that in PC, proteotoxic stress secondary to sustained Ig synthesis, leads to free Ub depletion thus causing impaired DDR. Most PC will be unable to recover from this crisis, however a small subset of genomically unstable PC may survive, presumably due to accumulation of survival promoting mutations, constituting a premalignant state for MM. We further hypothesize that Ub gene Ubc may be a haploinsufficient tumor suppressor genes in B cell malignancies. Herein, the applicant, Dr. Giada Bianchi, presents a comprehensive plan to test these hypotheses articulated in 2 specific aims: (1) to probe a causative link between Ig synthesis, Ub depletion and apoptosis in PC; and (2) to evaluate whether Ub depletion is sufficient to cause genomic instability in PC and drive MM pathogenesis. Data gathered during the course of our investigation will provide novel data regarding the biology of normal and malignant PC and potentially uncover a novel oncogenic mechanism - functional depletion of Ub - with applicability to other malignancies and opportunity for innovative, molecularly targeted therapies. To this end, Dr. Bianchi has carefully selected a mentoring committee and collaborators who are world-renowned experts in Ub, MM, DDR, proteomics and B cell biology. Such team will provide knowledge, models and technologies to render the testing of Dr. Bianchi’s hypotheses feasible within the proposed 5-year frame. The applicant’s mentoring committee has furthermore designed a detailed career plan based on regular meeting, attendance of workshops, classes and international meetings which will further accelerate the trajectory of Dr. Bianchi to become an independent investigator in cancer biology in the next 5 years.

项目总结/文摘