Fancd2-flox Mouse

FANCD2, the Fanconi anemia group D2 protein, is a pivotal component of the Fanconi anemia (FA) signaling pathway, a key genomic maintenance pathway. This pathway is activated in response to replication stress, and FANCD2 plays crucial roles in multiple aspects of cellular life, especially in the cellular responses to DNA damage [3].

Phosphorylation of FANCD2 by CHK1 triggers its FBXL12-dependent proteasomal degradation, facilitating its clearance at stalled replication forks and promoting efficient DNA replication under replication stress conditions [1]. Defects in the FA pathway, including those related to FANCD2, lead to R-loop accumulation, which contributes to genomic instability. The splicing factor SRSF1 and FANCD2 interact physically to suppress R-loop formation via mRNA export regulation [2]. Also, FANCD2-dependent mitotic DNA synthesis relies on PCNA K164 ubiquitination, as lack of this ubiquitination impairs FANCD2-dependent functions [4]. FANCD2-FANCI complex surveys DNA, binds to double-stranded DNA and stalls at single-stranded-double-stranded DNA junctions, identifying sites of DNA damage [5]. Monoubiquitination of FANCD2 and FANCI by the FA core complex is a key step in the FA pathway, and deubiquitination by the USP1-UAF1 complex is also critical for interstrand cross-link (ICL) repair [6,7]. In SHH medulloblastoma, FANCD2 is highly expressed, and its deficiency sensitizes the tumor cells to radiotherapy via ferroptosis [8]. A PP2A phosphatase complex dephosphorylates an inhibitory cluster in FANCD2, licensing its loading onto chromosomes in response to DNA damage [9]. In osteosarcoma, FANCD2 inhibits ferroptosis by regulating the JAK2/STAT3 pathway [10].

In conclusion, FANCD2 is essential for DNA damage response, replication fork protection, and regulation of processes like R-loop formation, mitotic DNA synthesis, and ferroptosis. Studies related to FANCD2, including those using loss-of-function models, have enhanced our understanding of its role in diseases such as cancer, highlighting its potential as a therapeutic target in certain cancers like SHH medulloblastoma and osteosarcoma.