Phosphorylation of the von Hippel-Lindau protein (VHL) by protein kinase CK2 reduces its protein stability and affects p53 and HIF-1alpha mediated transcription.
The von Hippel-Lindau tumour suppressor gene encodes a protein with 213 amino acids, which is known to be part of an E3-ubiquitin ligase targeting the HIF-1alpha transcription factor as well as to form a complex with p53. The VHL protein can be phosphorylated by protein kinase CK2 at serines 33, 38 and 43. However, the role of VHL phosphorylation in the context of p53 and HIF-1alpha regulation remained so far unknown. In the present study we investigated whether phosphorylation of VHL by CK2 might affect the function of p53 and HIF-1alpha. By using 4,5,6,7-tetrabromobenzotriazole (TBB), a CK2-specific inhibitor, as well as a mutant VHL where serines 33, 38 and 43 were replaced by alanines we found that CK2 phosphorylation affected the VHL protein half-life and increased VHL protein stability. Further, we found that inhibition of VHL phosphorylation by CK2 reduced p53 function. In addition, the enhanced levels of VHL due to CK2 inhibition contributed to the down-regulation of HIF-activity and degradation of HIF-1alpha. Thus, these results demonstrate that phosphorylation of VHL by CK2 plays an important role in the regulation of VHL protein stability and may contribute to the survival of tumour cells.
Ampofo
Emmanuel
E
Medizinische Biochemie und Molekularbiologie, Universität des Saarlandes, Homburg, Germany.
Kietzmann
Thomas
T
Zimmer
Andreas
A
Jakupovic
Mirza
M
Montenarh
Mathias
M
Götz
Claudia
C
D047390:Casein Kinase II / Q000037:antagonists & inhibitors / Q000378:metabolism*; D015536:Down-Regulation; D057809:HEK293 Cells; D006801:Humans; D051795:Hypoxia-Inducible Factor 1, alpha Subunit / Q000378:metabolism*; D016297:Mutagenesis, Site-Directed; D050505:Mutant Proteins / Q000235:genetics / Q000378:metabolism*; D010766:Phosphorylation; D011485:Protein Binding / Q000187:drug effects / Q000235:genetics; D055550:Protein Stability / Q000187:drug effects; D015533:Transcriptional Activation / Q000187:drug effects / Q000235:genetics; D019076:Transgenes / Q000235:genetics; D014230:Triazoles / Q000494:pharmacology; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism*; D051794:Von Hippel-Lindau Tumor Suppressor Protein / Q000235:genetics / Q000378:metabolism*
C405354:4,5,6,7-tetrabromobenzotriazole; C497442:HIF1A protein, human; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D050505:Mutant Proteins; D014230:Triazoles; D016159:Tumor Suppressor Protein p53; D051794:Von Hippel-Lindau Tumor Suppressor Protein; D047390:Casein Kinase II