Dataset Information

Fan1 deficiency results in DNA interstrand cross-link repair defects, enhanced tissue karyomegaly, and organ dysfunction.

ABSTRACT: Deficiency of FANCD2/FANCI-associated nuclease 1 (FAN1) in humans leads to karyomegalic interstitial nephritis (KIN), a rare hereditary kidney disease characterized by chronic renal fibrosis, tubular degeneration, and characteristic polyploid nuclei in multiple tissues. The mechanism of how FAN1 protects cells is largely unknown but is thought to involve FAN1's function in DNA interstrand cross-link (ICL) repair. Here, we describe a Fan1-deficient mouse and show that FAN1 is required for cellular and organismal resistance to ICLs. We show that the ubiquitin-binding zinc finger (UBZ) domain of FAN1, which is needed for interaction with FANCD2, is not required for the initial rapid recruitment of FAN1 to ICLs or for its role in DNA ICL resistance. Epistasis analyses reveal that FAN1 has cross-link repair activities that are independent of the Fanconi anemia proteins and that this activity is redundant with the 5'-3' exonuclease SNM1A. Karyomegaly becomes prominent in kidneys and livers of Fan1-deficient mice with age, and mice develop liver dysfunction. Treatment of Fan1-deficient mice with ICL-inducing agents results in pronounced thymic and bone marrow hypocellularity and the disappearance of c-kit(+) cells. Our results provide insight into the mechanism of FAN1 in ICL repair and demonstrate that the Fan1 mouse model effectively recapitulates the pathological features of human FAN1 deficiency.

SUBMITTER: Thongthip S

PROVIDER: S-EPMC4803051 | biostudies-literature |

REPOSITORIES: biostudies-literature

ACCESS DATA

Similar Datasets

Project description:DNA interstrand cross-links (ICLs) are products of chemotherapeutic agents and cellular metabolic processes that block both replication and transcription. If left unrepaired, ICLs are extremely toxic to cells, and ICL repair mechanisms contribute to the survival of certain chemotherapeutic resistance tumors. A critical step in ICL repair involves unhooking the cross-link. In the absence of a homologous donor sequence, the resulting gap can be filled in by a repair synthesis step involving bypass of the cross-link remnant. Here, we examine the effect of cross-link structure on the ability of unhooked DNA substrates to undergo repair synthesis in mammalian whole cell extracts. Using 32P incorporation assays, we found that repair synthesis occurs efficiently past the site of damage when a DNA substrate containing a single N4C-ethyl-N4C cross-link is incubated in HeLa or Chinese hamster ovary cell extracts. This lesion, which can base pair with deoxyguanosine, is readily bypassed by both Escherichia coli DNA polymerase I and T7 DNA polymerase in a primer extension assay. In contrast, bypass was not observed in the primer extension assay or in mammalian cell extracts when DNA substrates containing a N3T-ethyl-N3T or N1I-ethyl-N3T cross-link, whose linkers obstruct the hydrogen bond face of the bases, were used. A modified phosphorothioate sequencing method was used to analyze the ICL repair patches created in the mammalian cell extracts. In the case of the N4C-ethyl-N4C substrate, the repair patch spanned the site of the cross-link, and the lesion was bypassed in an error-free manner. However, although the N3T-ethyl-N3T and N1I-ethyl-N3T substrates were unhooked in the extracts, bypass was not detected. These and our previous results suggest that although the chemical structure of an ICL may not affect initial cross-link unhooking, it can play a significant role in subsequent processing of the cross-link. Understanding how the physical and chemical differences of ICLs affect repair may provide a better understanding of the cytotoxic and mutagenic potential of specific ICLs.

Dataset Information

Fan1 deficiency results in DNA interstrand cross-link repair defects, enhanced tissue karyomegaly, and organ dysfunction.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets