The function of oxidative phosphorylation in early B cell development

骨髓早期B细胞发育通过V(D)J/VJ重组和前B细胞增殖产生原代B细胞受体库（BCR）。在之前的工作中，我们已经描述了这种分化过程背后的代谢变化：我们发现在未转化的前B细胞和前B细胞中糖酵解和氧化磷酸化（OxPhos）相对减少。因此，我们最初怀疑糖酵解是驱动前b细胞扩增。然而，我们现在已经研究了氧化磷酸化（OxPhos）在早期B细胞发育中的作用。为此，我们通过mb1cre介导的重组在pro B细胞中诱导显性阴性线粒体解旋酶Twinkle （DNT）。DNT的表达减少了线粒体DNA （mtDNA）的拷贝数，从而减少了OxPhos。利用该系统，我们证明DNT的表达可以阻止前B细胞的形成，也可以阻止前B细胞中正常的IgM重链表达。一致地，这大大减少了前B细胞和成熟B细胞的数量。我们假设了在OxPhos大量减少的条件下调节前B细胞形成的几种机制。因此，该项目的总体目标是破译代谢，特别是OxPhos，前B细胞中IgM重链形成与随后的前B和B细胞发育之间的相互作用。我们将使用假设驱动和探索性方法的组合来解决主要问题。本课题涉及B细胞受体库的正常形成、衰老过程中受体库的改变、前B细胞的恶性转化以及B细胞耗竭后的B细胞再生。

Early B-cell development in bone marrow generates the primary B-cell receptor repertoire (BCR) through V(D)J/VJ recombination and proliferation of pre B cells. In previous work, we have described the metabolic changes underlying this differentiation process: We found a relative decrease in glycolysis versus oxidative phosphorylation (OxPhos) in nontransformed pre versus pro B cells. Therefore, we initially suspected that glycolysis was driving pre-B cell expansion. However, we have now investigated the role of oxidative phosphorylation (OxPhos) during early B cell development. To this end, we induced dominant-negative mitochondrial helicase Twinkle (DNT) in pro B cells by mb1Cre-mediated recombination. DNT expression reduces mitochondrial DNA (mtDNA) copy number, and thus OxPhos. Using this system, we demonstrated that DNT expression prevents pre-B cell formation as well as normal IgM heavy chain expression in pro B cells. Consistently, this greatly reduces the number of pre-B cells and mature B cells. We hypothesize several mechanisms that regulate the formation of pre B cells under conditions of greatly reduced OxPhos. The overall goal of this project is therefore to decipher the interplay between metabolism, in particular OxPhos, IgM heavy chain formation in pro-B cells and subsequent pre B and B cell development. We will use a combination of hypothesis-driven and exploratory approaches to address the main question. This project has references to the normal formation of the B cell receptor repertoire, its alteration in aging, malignant transformation of pre-B cells, and for B cell regeneration after B cell depletion.