Post translational modifications (PTM) of C/EBPß and functional implications

利用两种互补的筛选方法（APS和PRISMA），揭示了先驱转录因子C/EBPbeta的一个全面的和翻译后修饰（PTM）依赖的相互作用组，分别返回了大约650和1500个蛋白质组相互作用。实验诱导的淋巴细胞-髓细胞转分化表明，PTMs修饰C/EBPbeta决定了其重编程成髓细胞亚系的潜力，并提示了C/EBPbeta的表观遗传PTM索引代码。混合谱系标记表达是高C/EBPbeta表达的淋巴瘤实体的一个显著特征，包括霍奇金淋巴瘤、间变性大细胞淋巴瘤、曼特尔细胞淋巴瘤（HL、ALCL、MCL）和多发性骨髓瘤（MM）。我们认为谱系转换在肿瘤发生中与细胞反分化事件和选择性增殖优势有关。为了确定C/EBPbeta在转化和淋巴-髓细胞重编程中的核心功能，我们将采用最先进的质谱分析淋巴瘤细胞系和原代细胞中的C/EBPbeta PTM指数及其相互作用组，并结合基于CRISPR/Cas9的ALCL细胞系C/EBPbeta突变体功能基因组互补系统。最后，SUMOylation被确定为一个动态的PTM和额外的C/EBPbeta修饰的瓶颈。summoylation缺陷的C/EBPbeta，小鼠品系的β敲敲已经被构建，并将被检查以探索信号事件如何耦合到C/EBPbeta修饰和表观遗传功能。

A comprehensive and post-translational modification (PTM) dependent interactome of the pioneer transcription factor C/EBPbeta was disclosed using two complementary screening methods (APS and PRISMA) that returned approximately 650 and 1500 proteomic interactions, respectively. Experimentally induced lymphoid - myeloid trans-differen¬tiation revealed that decoration of C/EBPbeta with PTMs determines its reprogramming potential into myeloid sub-lineages and suggested an epigenetic PTM indexing-code on C/EBPbeta. Mixed lineage marker expression is a salient feature of lymphoma entities that express high C/EBPbeta levels, including Hodgkin-, anaplastic large cell-, Mantel cell lymphoma (HL, ALCL, MCL) and multiple myeloma (MM). We consider lineage switching in tumorigenesis in connection with cellular trans-differentiation events and a selective proliferative advantage. To determine the core functions of C/EBPbeta in transformation and lympho-myeloid reprogramming, we will employ state-of-the-art mass spectrometric analysis of the C/EBPbeta PTM index and its interactome in lymphoma cell lines and primary cells, in combination with a CRISPR/Cas9 based functional genomic complementation system of C/EBPbeta mutants in an ALCL cell line. Finally, SUMOylation was identified as a dynamic PTM and bottleneck for additional C/EBPbeta modifications. SUMOylation deficient C/EBPalpha,beta knock in mouse strains have been constructed and will be examined to explore how signaling events are coupled to C/EBPbeta modifications and epigenetic functions.