Interactome dynamics of RAF1-BRAF kinase monomers and dimers

RAF kinases play major roles in cancer. BRAFV600E mutants drive ~6% of human cancers. Potent kinase inhibitors exist but show variable effects in different cancer types, sometimes even inducing paradoxical RAF kinase activation. Both paradoxical activation and drug resistance are frequently due to enhanced dimerization between RAF1 and BRAF, which maintains or restores the activity of the downstream MEK-ERK pathway. Here, using quantitative proteomics we mapped the interactomes of RAF1 monomers, RAF1-BRAF and RAF1-BRAFV600E dimers identifying and quantifying >1,000 proteins. In addition, we examined the effects of vemurafenib and sorafenib, two different types of clinically used RAF inhibitors. Using regression analysis to compare different conditions we found a large overlapping core interactome but also distinct condition specific differences. Given that RAF proteins have kinase independent functions such dynamic interactome changes could contribute to their functional diversification. Analysing this dataset may provide a deeper understanding of RAF signalling and mechanisms of resistance to RAF inhibitors.

RAF激酶（RAF kinases）在癌症发生发展中扮演核心调控角色。BRAFV600E突变体驱动约6%的人类癌症病例。目前已有强效激酶抑制剂问世，但此类药物在不同癌种中的疗效存在显著差异，甚至有时会引发矛盾性RAF激酶激活。矛盾性激活与耐药性通常源于RAF1与BRAF间二聚化作用增强，该过程可维持或恢复下游MEK-ERK通路的活性。本研究借助定量蛋白质组学技术，绘制了RAF1单体、RAF1-BRAF异二聚体以及RAF1-BRAFV600E异二聚体的相互作用组图谱，共鉴定并定量了超过1000种蛋白质。此外，本研究还考察了两种临床常用的RAF抑制剂——维莫非尼（vemurafenib）与索拉非尼（sorafenib）的作用效果。通过回归分析对比不同实验条件，本研究发现三类样本存在大量重叠的核心相互作用组，但同时也存在各自特有的条件特异性差异。鉴于RAF蛋白存在不依赖于激酶活性的功能，此类动态的相互作用组变化或可推动其功能多样化。对本数据集进行分析，将有助于更深入地理解RAF信号通路以及RAF抑制剂的耐药机制。