Casein kinase II associates with Egr-1 and acts as a negative modulator of its DNA binding and transcription activities in NIH 3T3 cells.
Although the activation domains within early growth response gene protein 1 (Egr-1) have been mapped, little is known of the kinases which phosphorylate Egr-1 and how phosphorylation correlates with the transcriptional activity of Egr-1. In this study we report that casein kinase II (CKII) co-immunoprecipitates with Egr-1 from NIH 3T3 cell lysates. The association of Egr-1 and CKII requires the C terminus of Egr-1 and CKII phosphorylates Egr-1 in vitro. The in vitro phosphorylation of Egr-1 by CKII and that induced by serum in vivo was compared by examining the CNBr-digested fragments of the phosphorylated Egr-1. CKII strongly phosphorylates fragments 7 and 10 which cover part of the activation/nuclear localization and DNA binding domains of Egr-1. CKII also phosphorylates, albeit weakly, fragments 5 and 8 which cover part of activation domain and the entire repression domain of Egr-1, respectively. Strong phosphorylation on fragment 10 as well as fragment 5 was also observed in Egr-1 immunoprecipitated from serum-induced, 32P-labeled cells. CKII phosphorylation of Egr-1 resulted in a decrease of its DNA binding as well as its transcriptional activities.
Jain
N
N
Signal Transduction Laboratory, Institute of Molecular and Cell Biology, National University of Singapore, Singapore 119260, Republic of Singapore.
Mahendran
R
R
Philp
R
R
Guy
G R
GR
Tan
Y H
YH
Cao
X
X
D016475:3T3 Cells; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D001665:Binding Sites; D047390:Casein Kinase II; D004247:DNA / Q000235:genetics / Q000378:metabolism; D017931:DNA Primers / Q000235:genetics; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D051766:Early Growth Response Protein 1; D017874:Immediate-Early Proteins; D066298:In Vitro Techniques; D051379:Mice; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D010449:Peptide Mapping; D010766:Phosphorylation; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism*; D014157:Transcription Factors / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D014158:Transcription, Genetic
D017931:DNA Primers; D004268:DNA-Binding Proteins; D051766:Early Growth Response Protein 1; C486109:Egr1 protein, mouse; D017874:Immediate-Early Proteins; D010446:Peptide Fragments; D014157:Transcription Factors; D004247:DNA; D047390:Casein Kinase II; D017346:Protein Serine-Threonine Kinases