Chk2 regulates irradiation-induced, p53-mediated apoptosis in Drosophila.
The tumor suppressor function of p53 has been attributed to its ability to regulate apoptosis and the cell cycle. In mammals, DNA damage, aberrant growth signals, chemotherapeutic agents, and UV irradiation activate p53, a process that is regulated by several posttranslational modifications. In Drosophila melanogaster, however, the regulation modes of p53 are still unknown. Overexpression of D. melanogaster p53 (Dmp53) in the eye induced apoptosis, resulting in a small eye phenotype. This phenotype was markedly enhanced by coexpression with D. melanogaster Chk2 (DmChk2) and was almost fully rescued by coexpression with a dominant-negative (DN), kinase-dead form of DmChk2. DN DmChk2 also inhibited Dmp53-mediated apoptosis in response to DNA damage, whereas overexpression of Grapes (Grp), the Drosophila Chk1-homolog, and its DN mutant had no effect on Dmp53-induced phenotypes. DmChk2 also activated the Dmp53 transactivation activity in cultured cells. Mutagenesis of Dmp53 amino terminal Ser residues revealed that Ser-4 is critical for its responsiveness toward DmChk2. DmChk2 activates the apoptotic activity of Dmp53 and Ser-4 is required for this effect. Contrary to results in mammals, Grapes, the Drosophila Chk1-homolog, is not involved in regulating Dmp53. Chk2 may be the ancestral regulator of p53 function.
Peters
Malte
M
Advanced Medical Discoveries Institute, Ontario Cancer Institute, University of Toronto, 620 University Avenue, Toronto, ON, Canada M5G 2C1.
DeLuca
Carmela
C
Hirao
Atsushi
A
Stambolic
Vuk
V
Potter
Julia
J
Zhou
Lily
L
Liepa
Jennifer
J
Snow
Bryan
B
Arya
Sudha
S
Wong
Jorge
J
Bouchard
Denis
D
Binari
Richard
R
Manoukian
Armen S
AS
Mak
Tak W
TW
D000818:Animals; D030801:Animals, Genetically Modified; D017209:Apoptosis / Q000528:radiation effects*; D001483:Base Sequence; D002460:Cell Line; D000071877:Checkpoint Kinase 1; D064447:Checkpoint Kinase 2; D003001:Cloning, Molecular; D017931:DNA Primers / Q000235:genetics; D029721:Drosophila Proteins; D004331:Drosophila melanogaster / Q000166:cytology / Q000235:genetics / Q000528:radiation effects*; D005434:Flow Cytometry; D016158:Genes, p53 / Q000528:radiation effects; D016678:Genome; D006801:Humans; D007668:Kidney; D007700:Kinetics; D007814:Larva; D016366:Open Reading Frames; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism*; D011994:Recombinant Proteins / Q000378:metabolism; D014162:Transfection; D016159:Tumor Suppressor Protein p53 / Q000235:genetics / Q000378:metabolism*
D017931:DNA Primers; D029721:Drosophila Proteins; D011994:Recombinant Proteins; D016159:Tumor Suppressor Protein p53; D064447:Checkpoint Kinase 2; D000071877:Checkpoint Kinase 1; D017346:Protein Serine-Threonine Kinases; C000605877:grp protein, Drosophila; C112435:lok protein, Drosophila