HOMEPRODUCTSSERVICESCOMPANYCONTACTFAQResearchDictionaryPharmaMobileSign Up FREE or Login

Replication protein A2 phosphorylation after DNA damage by the coordinated action of ataxia telangiectasia-mutated and DNA-dependent protein kinase.

Abstract
Replication protein A (RPA, also known as human single-stranded DNA-binding protein) is a trimeric, multifunctional protein complex involved in DNA replication, DNA repair, and recombination. Phosphorylation of the RPA2 subunit is observed after exposure of cells to ionizing radiation (IR) and other DNA-damaging agents, which implicates the modified protein in the regulation of DNA replication after DNA damage or in DNA repair. Although ataxia telangiectasia-mutated (ATM) and DNA-dependent protein kinase (DNA-PK) phosphorylate RPA2 in vitro, their role in vivo remains uncertain, and contradictory results have been reported. Here we show that RPA2 phosphorylation is delayed in cells deficient in one of these kinases and completely abolished in wild-type, ATM, or DNA-PK-deficient cells after treatment with wortmannin at a concentration-inhibiting ATM and DNA-PK. Caffeine, an inhibitor of ATM and ATM-Rad3 related (ATR) but not DNA-PK, generates an ataxia-telangiectasia-like response in wild-type cells, prevents completely RPA2 phosphorylation in DNA-PKcs deficient cells, but has no effect on ataxia-telangiectasia cells. These observations rule out ATR and implicate both ATM and DNA-PK in RPA2 phosphorylation after exposure to IR. UCN-01, an inhibitor of protein kinase C, Chk1, and cyclin-dependent kinases, has no effect on IR-induced RPA2 phosphorylation. Because UCN-01 abrogates checkpoint responses, this observation dissociates RPA2 phosphorylation from checkpoint activation. Phosphorylated RPA has a higher affinity for nuclear structures than unphosphorylated RPA suggesting functional alterations in the protein. In an in vitro assay for DNA replication, DNA-PK is the sole kinase phosphorylating RPA2, indicating that processes not reproduced in the in vitro assay are required for RPA2 phosphorylation by ATM. Because RPA2 phosphorylation kinetics are distinct from those of the S phase checkpoint, we propose that DNA-PK and ATM cooperate to phosphorylate RPA after DNA damage to redirect the functions of the protein from DNA replication to DNA repair.
AuthorsH Wang, J Guan, H Wang, A R Perrault, Y Wang, G Iliakis
JournalCancer research (Cancer Res) Vol. 61 Issue 23 Pg. 8554-63 (Dec 1 2001) ISSN: 0008-5472 [Print] United States
PMID11731442 (Publication Type: Journal Article, Research Support, U.S. Gov't, P.H.S.)
Chemical References
  • Androstadienes
  • Cell Cycle Proteins
  • DNA, Neoplasm
  • DNA-Binding Proteins
  • Enzyme Inhibitors
  • Nuclear Proteins
  • RPA1 protein, human
  • Replication Protein A
  • Tumor Suppressor Proteins
  • Caffeine
  • ATM protein, human
  • Ataxia Telangiectasia Mutated Proteins
  • DNA-Activated Protein Kinase
  • PRKDC protein, human
  • Protein-Serine-Threonine Kinases
  • wortmannin
Topics
  • Androstadienes (pharmacology)
  • Ataxia Telangiectasia Mutated Proteins
  • Caffeine (pharmacology)
  • Cell Cycle Proteins
  • DNA Damage (physiology)
  • DNA, Neoplasm (radiation effects)
  • DNA-Activated Protein Kinase
  • DNA-Binding Proteins (metabolism)
  • Enzyme Inhibitors (pharmacology)
  • HeLa Cells
  • Humans
  • Nuclear Proteins
  • Phosphorylation (radiation effects)
  • Protein-Serine-Threonine Kinases (antagonists & inhibitors, metabolism)
  • Replication Protein A
  • Tumor Suppressor Proteins

Join CureHunter, for free Research Interface BASIC access!

Take advantage of free CureHunter research engine access to explore the best drug and treatment options for any disease. Find out why thousands of doctors, pharma researchers and patient activists around the world use CureHunter every day.
Realize the full power of the drug-disease research network!


Choose Username:
Email:
Password:
Verify Password: