Serine/threonine-protein kinase involved in transcription regulation and TNF-mediated cellular apoptosis. Plays a role as a corepressor for homeodomain transcription factors. Phosphorylates DAXX and MYB. Phosphorylates DAXX in response to stress, and mediates its translocation from the nucleus to the cytoplasm. Inactivates MYB transcription factor activity by phosphorylation. Prevents MAP3K5-JNK activation in the absence of TNF. TNF triggers its translocation to the cytoplasm in response to stress stimuli, thus activating nuclear MAP3K5-JNK by derepression and promoting apoptosis. May be involved in anti-oxidative stress responses. Involved in the regulation of eye size, lens formation and retinal lamination during late embryogenesis. Promotes angiogenesis and to be involved in erythroid differentiation. May be involved in malignant squamous cell tumor formation. Phosphorylates PAGE4 at 'Thr-51' which is critical for the ability of PAGE4 to potentiate the transcriptional activator activity of JUN (PubMed:24559171).
HIPK1 phosphorylates Daxx on Ser 669, and phosphorylation of this site is important in modulating the ability of Daxx to function as a transcriptional repressor. | Therefore, phosphorylation at Ser 669 by HIPK1 diminishes the ability of Daxx to repress transcription.
Here, we have identified homeodomain-interacting protein kinase 1 (HIPK1), also a component of the stress-response pathway, as a kinase that phosphorylates PAGE4 at T51 | We show that phosphorylation of PAGE4 is critical for its transcriptional activity since mutating this T residue abolishes its ability to potentiate c-Jun transactivation.