The human protein kinase HIPK2 phosphorylates and downregulates the methyl-binding transcription factor ZBTB4.
HIPK2 is a eukaryotic Serine-Threonine kinase that controls cellular proliferation and survival in response to exogenous signals. Here, we show that the human transcription factor ZBTB4 is a new target of HIPK2. The two proteins interact in vitro, colocalize and associate in vivo, and HIPK2 phosphorylates several conserved residues of ZBTB4. Overexpressing HIPK2 causes the degradation of ZBTB4, whereas overexpressing a kinase-deficient mutant of HIPK2 has no effect. The chemical activation of HIPK2 also decreases the amount of ZBTB4 in cells. Conversely, the inhibition of HIPK2 by drugs or by RNA interference causes a large increase in ZBTB4 levels. This negative regulation of ZBTB4 by HIPK2 occurs under normal conditions of cell growth. In addition, the degradation is increased by DNA damage. These findings have two consequences. First, we have recently shown that ZBTB4 inhibits the transcription of p21. Therefore, the activation of p21 by HIPK2 is two-pronged: stimulation of the activator p53, and simultaneous repression of the inhibitor ZBTB4. Second, ZBTB4 is also known to bind methylated DNA and repress methylated sequences. Consequently, our findings raise the possibility that HIPK2 might influence the epigenetic regulation of gene expression at loci that remain to be identified.
Yamada
D
D
CNRS UMR218, Institut Curie, Paris, France.
Pérez-Torrado
R
R
Filion
G
G
Caly
M
M
Jammart
B
B
Devignot
V
V
Sasai
N
N
Ravassard
P
P
Mallet
J
J
Sastre-Garau
X
X
Schmitz
M L
ML
Defossez
P-A
PA
D000595:Amino Acid Sequence; D000818:Animals; D015153:Blotting, Western; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism*; D045744:Cell Line, Tumor; D004249:DNA Damage; D015536:Down-Regulation; D045325:HCT116 Cells; D006801:Humans; D047468:Immunoprecipitation; D008164:Luminescent Proteins / Q000235:genetics / Q000378:metabolism; D051379:Mice; D008969:Molecular Sequence Data; D009154:Mutation; D041681:NIH 3T3 Cells; D010766:Phosphorylation; D011485:Protein Binding; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism*; D034622:RNA Interference; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017386:Sequence Homology, Amino Acid; D013912:Threonine / Q000378:metabolism; D020798:Two-Hybrid System Techniques
D002352:Carrier Proteins; D008164:Luminescent Proteins; D012097:Repressor Proteins; C508974:ZBTB4 protein, human; D013912:Threonine; C115114:HIPK2 protein, human; D017346:Protein Serine-Threonine Kinases