Cooperation of DNA-PKcs and WRN helicase in the maintenance of telomeric D-loops

TY - JOUR

T1 - Cooperation of DNA-PKcs and WRN helicase in the maintenance of telomeric D-loops

AU - Kusumoto-Matsuo, Rika

AU - Opresko, Patricia L

AU - Ramsden, Dale

AU - Tahara, Hidetoshi

AU - Bohr, Vilhelm A

PY - 2010/5/1

Y1 - 2010/5/1

N2 - Werner syndrome is an inherited human progeriod syndrome caused by mutations in the gene encoding the Werner Syndrome protein, WRN. It has both 3'-5' DNA helicase and exonuclease activities, and is suggested to have roles in many aspects of DNA metabolism, including DNA repair and telomere maintenance. The DNA-PK complex also functions in both DNA double strand break repair and telomere maintenance. Interaction between WRN and the DNA-PK complex has been reported in DNA double strand break repair, but their possible cooperation at telomeres has not been reported. This study analyzes thein vitro and in vivo interaction at the telomere between WRN and DNA-PKcs, the catalytic subunit of DNA-PK. The results show that DNA-PKcs selectively stimulates WRN helicase but not WRN exonuclease in vitro, affecting that WRN helicase unwinds and promotes the release of the full-length invading strand of a telomere D-loop model substrate. In addition, the length of telomeric G-tails decreases in DNA-PKcs knockdown cells, and this phenotype is reversed by overexpression of WRN helicase. These results suggest that WRN and DNA-PKcs may cooperatively prevent G-tail shortening in vivo.

AB - Werner syndrome is an inherited human progeriod syndrome caused by mutations in the gene encoding the Werner Syndrome protein, WRN. It has both 3'-5' DNA helicase and exonuclease activities, and is suggested to have roles in many aspects of DNA metabolism, including DNA repair and telomere maintenance. The DNA-PK complex also functions in both DNA double strand break repair and telomere maintenance. Interaction between WRN and the DNA-PK complex has been reported in DNA double strand break repair, but their possible cooperation at telomeres has not been reported. This study analyzes thein vitro and in vivo interaction at the telomere between WRN and DNA-PKcs, the catalytic subunit of DNA-PK. The results show that DNA-PKcs selectively stimulates WRN helicase but not WRN exonuclease in vitro, affecting that WRN helicase unwinds and promotes the release of the full-length invading strand of a telomere D-loop model substrate. In addition, the length of telomeric G-tails decreases in DNA-PKcs knockdown cells, and this phenotype is reversed by overexpression of WRN helicase. These results suggest that WRN and DNA-PKcs may cooperatively prevent G-tail shortening in vivo.

KW - Calcium-Binding Proteins

KW - Cell Line

KW - DNA

KW - DNA Repair

KW - Exodeoxyribonucleases

KW - Humans

KW - RecQ Helicases

KW - Telomere

KW - Werner Syndrome

M3 - Journal article

C2 - 20519774

SN - 1945-4589

VL - 2

SP - 274

EP - 284

JO - Aging

JF - Aging

IS - 5

ER -