Chkl binds and phosphorylates BAD protein.
Chk1 (checkpoint kinase 1) is a serine-threonine kinase that is critical for G2/M arrest in response to DNA damage. Chk1 phosphorylates Cdc25C at serine-216, a major regulatory site, in response to DNA damage. Furthermore, Chk1 also phosphorylates Cdc25A on serine 123 which accelerates its degradation through the ubiquitin-proteasome pathway and arrests cells in late G2-phase after DNA damage. In the present study, we demonstrated that Chk1 phosphorylates pro-apoptotic protein BAD (Bcl-2/Bcl-XL-Antagonist, causing cell Death) in vitro. In vitro phosphorylation analysis with various mouse BAD peptides has revealed two phosphorylation sites for Chk1 at serine-155 and serine-170. When wild-type and mutant BAD (S155A) constructs were transfected into 293T cells, an association between BAD and Chk1 was observed by co-immunoprecipitation. In addition, there was an increase in the phosphorylation of serine-155 following DNA damage by adriamycin treatment. Our results suggest that Chk1 associates with BAD and phosphorylates the BAD protein at serine-155. Taken together, our results suggest that Chk1 may inactivate BAD by associating with and phosphorylating residues critical for BAD function in response to DNA damage.
Han
Edward Kyu-ho
EK
Department R47S, AP9A, Cancer Research, Global Pharmaceutical Research Division, Abbott Laboratories, 100 Abbott Park Road, Abbott Park, IL 60064, USA. edward.k.han@abbott.com
Butler
Chris
C
Zhang
Haichao
H
Severin
Jean M
JM
Qin
Wenying
W
Holzman
Tom F
TF
Gubbins
Earl J
EJ
Simmer
Robert L
RL
Rosenberg
Saul
S
Giranda
Vincent L
VL
Ng
Shi-Chung
SC
Luo
Y
Y
D000595:Amino Acid Sequence; D002352:Carrier Proteins / Q000378:metabolism*; D002460:Cell Line; D000071877:Checkpoint Kinase 1; D004622:Embryo, Mammalian; D006801:Humans; D007668:Kidney / Q000166:cytology; D008969:Molecular Sequence Data; D011106:Polyisoprenyl Phosphates; D011485:Protein Binding; D011494:Protein Kinases / Q000378:metabolism*; D051025:bcl-Associated Death Protein
C494819:BAD protein, human; D002352:Carrier Proteins; D011106:Polyisoprenyl Phosphates; D051025:bcl-Associated Death Protein; C105485:phosprenyl; D011494:Protein Kinases; C000605867:CHEK1 protein, human; D000071877:Checkpoint Kinase 1; C000605869:Chek1 protein, mouse