Bloom's syndrome (BS), an autosomal recessive disorder, is characterized by short stature, sunlight sensitivity, an increased susceptibility to infections and respiratory illness, and a strong disposition to a wide spectrum of cancers. The mean age of death is 27 years and the cause is most frequently cancer-related. At the cellular level, BS exhibits highly elevated levels of sister chromatid exchanges, interhomologue recombination, and ectopic recombination, indicative of homologous recombination (HR) deregulation. It has been proposed that abnormal HR events lead to the general destabilization of the genome in BS, manifested as chromosome aberrations and rearrangements including breaks, quadriradials, and translocations. BLM, the protein encoded by the gene mutated in BS, is a member of the RecQ helicase family. BLM has the ability to unwind DNA substrates including those that resemble HR intermediates, and it works in conjunction with Topo III alpha, a type IA topoisomerase, to dissolve the double Holliday junction (DHJ) to yield non-crossover recombinants. BLM also associates with a novel polypeptide BLAP75 and binds the hRad51 recombinase. Importantly, our preliminary studies have found a dramatic stimulatory effect of BLAP75 on the reactions mediated by BLM-Topo III alpha. This research project comprising molecular studies under three specific aims strives to decipher the biological significance of the BLM-Topo III alpha-BLAP75 (BTB) complex with regard to the processing of HR intermediates, defining HR pathway choice, and regulating the activity of hRad51. Specifically, we will (1) delineate the functional roles of BLM, Topo III alpha, and BLAP75 in the BTB complex needed for HR modulation, (2) define the contributions of BLAP75-mediated ligand interactions to BTB complex functions, and (3) test hypotheses concerning the functional significance of the BLM-hRad51 interaction. The results from our research endeavors will shed mechanistic light on BLM-dependent control mechanisms of HR and will provide an explanation for the genome instability and cancer susceptibility in BS patients.

Agency
National Institute of Health (NIH)
Institute
National Institute of Environmental Health Sciences (NIEHS)
Type
Research Project (R01)
Project #
5R01ES015632-04
Application #
7793626
Study Section
Radiation Therapeutics and Biology Study Section (RTB)
Program Officer
Reinlib, Leslie J
Project Start
2007-04-16
Project End
2012-03-31
Budget Start
2010-04-01
Budget End
2011-03-31
Support Year
4
Fiscal Year
2010
Total Cost
$361,278
Indirect Cost
Name
Yale University
Department
Biochemistry
Type
Schools of Medicine
DUNS #
043207562
City
New Haven
State
CT
Country
United States
Zip Code
06520
Crickard, J Brooks; Kaniecki, Kyle; Kwon, YoungHo et al. (2018) Spontaneous self-segregation of Rad51 and Dmc1 DNA recombinases within mixed recombinase filaments. J Biol Chem 293:4191-4200
Crickard, J Brooks; Kaniecki, Kyle; Kwon, Youngho et al. (2018) Meiosis-specific recombinase Dmc1 is a potent inhibitor of the Srs2 antirecombinase. Proc Natl Acad Sci U S A 115:E10041-E10048
Gobbini, Elisa; Cassani, Corinne; Vertemara, Jacopo et al. (2018) The MRX complex regulates Exo1 resection activity by altering DNA end structure. EMBO J 37:
Kaniecki, Kyle; De Tullio, Luisina; Gibb, Bryan et al. (2017) Dissociation of Rad51 Presynaptic Complexes and Heteroduplex DNA Joints by Tandem Assemblies of Srs2. Cell Rep 21:3166-3177
Daley, James M; Jimenez-Sainz, Judit; Wang, Weibin et al. (2017) Enhancement of BLM-DNA2-Mediated Long-Range DNA End Resection by CtIP. Cell Rep 21:324-332
De Tullio, Luisina; Kaniecki, Kyle; Kwon, Youngho et al. (2017) Yeast Srs2 Helicase Promotes Redistribution of Single-Stranded DNA-Bound RPA and Rad52 in Homologous Recombination Regulation. Cell Rep 21:570-577
Buzovetsky, Olga; Kwon, Youngho; Pham, Nhung Tuyet et al. (2017) Role of the Pif1-PCNA Complex in Pol ?-Dependent Strand Displacement DNA Synthesis and Break-Induced Replication. Cell Rep 21:1707-1714
Kumar, S; Peng, X; Daley, J et al. (2017) Inhibition of DNA2 nuclease as a therapeutic strategy targeting replication stress in cancer cells. Oncogenesis 6:e319
Wang, Weibin; Daley, James M; Kwon, Youngho et al. (2017) Plasticity of the Mre11-Rad50-Xrs2-Sae2 nuclease ensemble in the processing of DNA-bound obstacles. Genes Dev 31:2331-2336
Chen, Xuefeng; Niu, Hengyao; Yu, Yang et al. (2016) Enrichment of Cdk1-cyclins at DNA double-strand breaks stimulates Fun30 phosphorylation and DNA end resection. Nucleic Acids Res 44:2742-53

Showing the most recent 10 out of 46 publications