Functional Interaction between the Fanconi Anemia D2 Protein and Proliferating Cell Nuclear Antigen (PCNA) via a Conserved Putative PCNA Interaction Motif

The USP1-UAF1 complex interacts with RAD51AP1 to promote homologous recombination repair

“…34 Unmodified FANCD2 is also required for chromatin loading of Blm, 35 and functionally interacts with FANCJ [36][37][38] and PCNA. 39 Among these functions of FANCD2, the recruitment of CtIP to the DSB ends would have significant effects on the HR repair, as the CtIP-induced DSB end resection is the initiating event of the HR repair process. Whether USP1 and UAF1 influence DSB end resection through FANCD2 deubiquitination remains a possibility, although our analysis suggests that they may only play a minor role in the process when cells were challenged with CPT (Fig.…”

The Fanconi anemia ID2 complex: Dueling saxes at the crossroads

“…26 FANCD2 contains a highly conserved PIP-motif (PCNA-interacting protein motif) which is necessary for the association of FANCD2 with PCNA (proliferating cell nuclear antigen), and for efficient FANCD2 monoubiquitination, nuclear foci formation and ICL repair, suggesting that PCNA may function as a molecular scaffold to facilitate FANCD2 function. 26 FANCD2 also harbors an amino-terminal CUE (coupling of ubiquitin conjugation to endoplasmic reticulum degradation) ubiquitin-binding domain (UBD). 27 The CUE domain adopts a triple a-helical configuration and mediates noncovalent ubiquitin binding.…”

“…For example, as mentioned earlier, FANCD2 interacts with the DNA polymerase processivity factor PCNA, via a conserved PIPbox, and this interaction is necessary for efficient FANCD2 monoubiquitination and ICL repair. 26 In addition, using a method called iPOND (isolation of proteins on nascent DNA), the Cortez group recently discovered that FANCD2 and FANCI, in addition to ATR, MRE11 and other proteins, are highly enriched at stalled and collapsed replication forks following depletion of deoxyribonucleotide pools. 112 Interestingly, FANCI, and not FANCD2, was also shown to accumulate at active replication forks prior to fork staling, suggesting common and independent functions for these proteins.…”

The E3 ubiquitin ligase RAD18 regulates ubiquitylation and chromatin loading of FANCD2 and FANCI

“…[6][7][8] Monoubiquitylated FANCD2 and FANCI are readily loaded onto chromatin, 9 where they colocalize in nuclear repair foci with FANCD1, FANCJ, and FANCN, as well as other DNA repair factors such as BRCA1 and RAD51 and the DNA replication processivity factor proliferating cell nuclear antigen (PCNA). [10][11][12][13] RAD18 is an E3 ubiquitin ligase best known for its role in the monoubiquitylation of PCNA in response to stalled replication forks. [14][15] Monoubiquitylation of PCNA on lysine-164 by RAD18 and its partner E2 enzyme, RAD6, triggers a mechanism known as polymerase switching.…”

“…The expression of RAD18 in HCT116 RAD18 Ϫ/Ϫ cells using adenoviral vectors resulted in partial correction of the defect in FANCD2 monoubiquitylation in untreated cells (compare lanes 2 and 4 in Figure 2D). Because RAD18 is known to monoubiquitylate PCNA, and it has recently been reported that PCNA interacts with FANCD2, 12 we next sought to determine whether the effect of RAD18 on FANCD2 monoubiquitylation was an indirect result of modification of PCNA. Using MRC-5 cells that express a ubiquitylationresistant form of PCNA harboring silent mutations that render it resistant to depletion by siRNA, 23 we depleted endogenous PCNA by siRNA transfection.…”