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Note for: Cooperative Roles of Vertebrate Fbh1 and Blm DNA Helicases in Avoidance of Crossovers during Recombination Initiated by Replication Fork Collapse (doi: 10.1128/MCB.02043-06) Fbh1 (F-box DNA helicase 1) -- treating with the DNA damaging agents; no prominent phenotype, contradict with yeast -- there might be the compensate pw in DT40. FBH(-/-) phenotype in DT40; 1.increase sister chromatid exchange 2.formation of radial structures 3.prevent extensive strand exchange during HR 4.work with Bloom helicase - controling recombination-mediated DSB repair at replication block 5.work with Bloom helicase - reduce frequency of crossover Two major pw to release the replication block; 1. TLS -- using TLS polymerase, synthesis directly across the DNA damage 2. HR -- transient template switch from the damage to newly synthesized daughter strands There has been proposed that db holliday junctions are dissolved by concerted action of RecQ helicase, Blm and Topo-IIIalpha R...

Note for: Disruption of the BLM gene in ATM-null DT40 cells does not exacerbate either phenotype (doi: 10.1038/sj.onc.1207276 ) BLM and ATM; 1. autosomal recessive human disorder 2. immunodefficiency 3. genome instability 4. predisposition to develop cancer -- - BLM interact with ATM and recognize the abnormal DNA structures from the literature - in DT40; BLM+ATM-KO viable - no exacerbation of this KO is observed - in the end, conclude that each protein has "largely" distinct roles in recognizing the DNA lesion-but there are some parts overlap. ATM phosphorylates Nbs1 at Ser343-->stop Nbs to play role as lesion detection but change the function to be the adaptor and facilitating ATM-dependent phosphorylation of structural maintenance of structural maintenance of chromosome protein (SMC1)-->S-phase checkpoint ATM-->phosphorylate FANCD2 on Ser222--> it is suggested the role in ATM-FA damage response. Characteristic of BS-autosomal re...

Note for: Werner and Bloom helicases are involved in DNA repair in a complementary fashion (doi:  https://doi.org/10.1038/sj.onc.1205143 ) Werner syndrome; 1. rare autosomal recessive disorder 2. premature senescence Bloom syndrome; 1. short stature 2. immunodeficiency 3. rare autosomal recessive common for these two; 1. chromosomal instability-->tumorigenesis WRN and BLM-->closely relate to RecQ helicase WRN and BLM - involve in DNA repair in a complementary fashion. Both BLM and WRN; 1. contain 7 signature motifs conserved in DNA/RNA helicases 2. BLM shows most similarity to RecQ subfamily of DNA helicases Recombinant WRN and BLM; 1. unwind duplex DNA in 3-5 direction with 3' overhang tail 2. both interact with RPA to facilitate the unwinding WRN has the exonuclease activity (N-terminal) which functions as proofreading during the DNA synthesis. BLM and WRN show very different profiles of sensitivity toward DNA da...