DNA damage in transcribed genes induces apoptosis via the JNK pathway and the JNK-phosphatase MKP-1.
The nucleotide excision repair (NER) system consists of two sub-pathways, global genome repair (GGR) and transcription-coupled repair (TCR), which exhibit distinct functions in the cellular response to genotoxic stress. Defects in TCR result in prolonged UV light-induced stalling of RNA polymerase II and hypersensitivity to apoptosis induced by UV and certain chemotherapeutic drugs. Here, we show that low doses of UV trigger delayed activation of the stress-induced MAPkinase JNK and its proapoptotic targets c-Jun and ATF-3 in TCR-deficient primary human fibroblasts from Xeroderma Pigmentosum (XP) and Cockayne syndrome (CS) patients. This delayed activation of the JNK pathway is not observed in GGR-deficient TCR-proficient XP cells, is independent of functional p53, and is established through repression of the JNK-phosphatase MKP-1 rather than by activation of the JNK kinases MKK4 and 7. Enzymatic reversal of UV-induced cyclobutane pyrimidine dimers (CPDs) by CPD photolyase abrogated JNK activation, MKP-1 repression, and apoptosis in TCR-deficient XPA cells. Ectopic expression of MKP-1 inhibited DNA-damage-induced JNK activity and apoptosis. These results identify both MKP-1 and JNK as sensors and downstream effectors of persistent DNA damage in transcribed genes and suggest a link between the JNK pathway and UV-induced stalling of RNApol II.
Hamdi
Mohamed
M
Department of Molecular Cell Biology, Leiden University Medical Center, Wassenaarseweg 72, 2333AL Leiden, The Netherlands.
Kool
Jaap
J
Cornelissen-Steijger
Paulien
P
Carlotti
Francoise
F
Popeijus
Herman E
HE
van der Burgt
Corina
C
Janssen
Josephine M
JM
Yasui
Akira
A
Hoeben
Rob C
RC
Terleth
Carrol
C
Mullenders
Leon H
LH
van Dam
Hans
H
D017209:Apoptosis / Q000528:radiation effects*; D018797:Cell Cycle Proteins / Q000378:metabolism*; D002461:Cell Line, Transformed; D002472:Cell Transformation, Viral; D002478:Cells, Cultured; D003057:Cockayne Syndrome / Q000235:genetics; D004249:DNA Damage; D004260:DNA Repair; D054638:Dual Specificity Phosphatase 1; D005347:Fibroblasts / Q000528:radiation effects; D005434:Flow Cytometry; D006801:Humans; D017874:Immediate-Early Proteins / Q000378:metabolism*; D048031:JNK Mitogen-Activated Protein Kinases / Q000378:metabolism*; D010749:Phosphoprotein Phosphatases / Q000378:metabolism*; D054645:Protein Phosphatase 1; D017027:Protein Tyrosine Phosphatases / Q000378:metabolism*; D018808:Transcription Factor AP-1 / Q000378:metabolism; D014158:Transcription, Genetic; D014466:Ultraviolet Rays; D014983:Xeroderma Pigmentosum / Q000235:genetics; D051760:Xeroderma Pigmentosum Group A Protein / Q000378:metabolism
D018797:Cell Cycle Proteins; D017874:Immediate-Early Proteins; D018808:Transcription Factor AP-1; D051760:Xeroderma Pigmentosum Group A Protein; D048031:JNK Mitogen-Activated Protein Kinases; D010749:Phosphoprotein Phosphatases; D054645:Protein Phosphatase 1; C517019:DUSP1 protein, human; D054638:Dual Specificity Phosphatase 1; D017027:Protein Tyrosine Phosphatases