BTF Interacts With BACH1 To Participate In DNA Damage Repair

BTF(Bcl2 associated transcription factor 1,BTF or BCALF1)was originally identified as a protein that interacts with anti-apoptotic members of the BCL2 family.Preliminary studies have shown that this protein acts as an apoptosis-inducing factor and a transcriptional repressor.Subsequent studies have shown that BTF plays a key role in a wide range of processes that are not normally associated with the role of BCL2 family members,including lung development,T cell activation,and the control of lytic infection programs of Kaposi sarcoma-associated herpes viruses.Recent studies indicate that BTF plays a role in the post-transcriptional process that affects mRNA metabolism.BACH1(BRCA1 interacting protein C-terminal helicase 1)is known to be involved in the Fanconi anemia signaling pathway and homologous recombination repair(HR).BRCA1(Breast cancer 1,early onset,BRCA1)is the core protein of HR.BRCA1 can interacts with BACH1 then participates in homologous recombination repair.Our initial study found that BTF was present in purified BACH1,suggests that both BTF and BACH1 are in a common complex.Previous reports did not address the existence of a common signaling network with BTF and BACH1.In order to identify the key region(s)for the interaction between BTF and BACH1,SFB-BTF,GFP-BACH1 wild type and several mutated plasmids were transiently transfected in U2 OS cells.CoIP results have shown that amino acid of BTF from 625 to 716 is important for the interaction between BTF and BACH1,which has been confirmed by GST pull-down experiments.To further explore the mechanisms by which BTF involved in DNA damage response,we tested the cellular location of BTF following induced DNA damage.We constructed GFP-BTF and GFP-BACH1 respectively,and observed that BTF and BACH1 were recruited to DNA damage sites induced by laser-induced DNA damage.In wild type cells,BTF and BACH1 are rapidly recruited to the DNA damage sites.In addition,we found that when BACH1 is knocked down by siRNA,BTF cannot be recruited to the DNA damage sites.In the BRCA1 deficiency cell line HCC1937,BTF and BACH1 could not be recruited to DNA damage sites.These results suggested that BRCA1 is in the upstream of the BACH1 and BTF?...