Proline Hydroxylation Primes Protein Kinases for Autophosphorylation and Activation.

Area of Science:

• Molecular Biology
• Biochemistry
• Cell Biology

Background:

• Dual-specificity tyrosine-phosphorylation-regulated kinases 1A and 1B (DYRK1A/B) activation depends on prolyl hydroxylation by PHD1 prolyl hydroxylase.
• Prolyl hydroxylation of DYRK1 triggers events releasing constraints on the von Hippel-Lindau (VHL) tumor suppressor.
• The specific proline residue targeted for hydroxylation and its role in DYRK1 tyrosine autophosphorylation were previously unknown.

Purpose of the Study:

• Identify the proline residue in DYRK1 hydroxylated by PHD1.
• Elucidate the role of prolyl hydroxylation in DYRK1 tyrosine autophosphorylation.
• Investigate the functional consequences of impaired prolyl hydroxylation on DYRK1 activity and VHL function.

Main Methods:

• Site-directed mutagenesis to identify the hydroxylation site.
• Biochemical assays to assess kinase activity and tyrosine autophosphorylation.
• Functional assays to evaluate VHL preservation and glioma suppression.

Main Results:

• A conserved proline in the DYRK1 kinase domain's CMGC insert is hydroxylated by PHD1.
• This hydroxylation event precedes and is necessary for tyrosine autophosphorylation.
• Mutating the hydroxylation site prevents DYRK1 autophosphorylation, proper folding, VHL function preservation, and glioma suppression.

Conclusions:

• Prolyl hydroxylation is a critical step in DYRK1 kinase maturation and activation.
• This hydroxylation mechanism is essential for DYRK1's role in VHL regulation and tumor suppression.
• Prolyl hydroxylation likely represents a general regulatory mechanism for CMGC kinases in eukaryotes.