Ubiquitination-Linked Phosphorylation of the FANCI S/TQ Cluster Contributes to Activation of the Fanconi Anemia I/D2 Complex

• Published in: Cell reports (Cambridge) Vol. 19; no. 12; pp. 2432 - 2440
• Main Authors: Cheung, Ronald S., Castella, Maria, Abeyta, Antonio, Gafken, Philip R., Tucker, Nyka, Taniguchi, Toshiyasu
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 20.06.2017; Elsevier
• Subjects: ATR; DNA damage response; DNA repair; FANCD2; FANCI; Fanconi anemia; Fanconi Anemia Complementation Group D2 Protein - metabolism; Fanconi Anemia Complementation Group Proteins - metabolism; HEK293 Cells; Humans; interstrand crosslink; monoubiquitination; Phosphorylation; Proteolysis; Serine - metabolism; Ubiquitination; USP1; FANCI; Fanconi anemia; interstrand crosslink; FANCD2; DNA damage response; USP1; DNA repair; phosphorylation; monoubiquitination; ATR
• ISSN: 2211-1247; 2211-1247
• DOI: 10.1016/j.celrep.2017.05.081

Repair of interstrand crosslinks by the Fanconi anemia (FA) pathway requires both monoubiquitination and de-ubiquitination of the FANCI/FANCD2 (FANCI/D2) complex. In the standing model, the phosphorylation of six sites in the FANCI S/TQ cluster domain occurs upstream of, and promotes, FANCI/D2 monoubiquitination. We generated phospho-specific antibodies against three different S/TQ cluster sites (serines 556, 559, and 565) on human FANCI and found that, in contrast to the standing model, distinct FANCI sites were phosphorylated either predominantly upstream (ubiquitination independent; serine 556) or downstream (ubiquitination-linked; serines 559 and 565) of FANCI/D2 monoubiquitination. Ubiquitination-linked FANCI phosphorylation inhibited FANCD2 de-ubiquitination and bypassed the need to de-ubiquitinate FANCD2 to achieve effective interstrand crosslink repair. USP1 depletion suppressed ubiquitination-linked FANCI phosphorylation despite increasing FANCI/D2 monoubiquitination, providing an explanation of why FANCD2 de-ubiquitination is important for function of the FA pathway. Our work results in a refined model of how FANCI phosphorylation activates the FANCI/D2 complex. [Display omitted] •FANCI phosphorylation may be either independent of or linked to ubiquitination•Ubiquitination-linked FANCI phosphorylation inhibits FANCD2 de-ubiquitination•Ubiquitination-linked FANCI phosphorylation fully activates the FANCI/D2 complex•Impairing USP1 suppresses ubiquitination-linked FANCI phosphorylation How the Fanconi anemia pathway is activated to repair interstrand crosslinks is incompletely understood. Cheung et al. use FANCI-phosphorylation-specific antibodies to identify ubiquitination-linked FANCI phosphorylation. Ubiquitination-linked FANCI phosphorylation fully activates the FANCI/D2 complex so that it can function without needing to undergo de-ubiquitination.