Cyclin-dependent kinase 5 phosphorylates serine 31 of tyrosine hydroxylase and regulates its stability.
Tyrosine hydroxylase (TH) is the rate-limiting enzyme in catecholamine biosynthesis, and its activity is regulated by phosphorylation in the N-terminal regulatory domain. The proline-directed serine/threonine kinase cyclin-dependent kinase 5 (cdk5) plays an important role in diverse neuronal processes. In the present study, we identify TH as a novel substrate of cdk5. We show that cdk5 phosphorylates TH at serine 31 and that this phosphorylation is associated with an increase in total TH activity. In transgenic mice with increased cdk5 activity, the immunoreactivity for phosphorylated TH at Ser-31 is enhanced in neurons of the substantia nigra, a brain region enriched with TH-positive neurons. In addition, we demonstrate that co-expression of cdk5 and its regulatory activator p35 with TH increases the stability of TH. Consistent with these findings, TH protein levels are reduced in cdk5 knock-out mice. Importantly, the TH activity and protein turnover of the phosphorylation-defective mutant TH S31A was not altered by cdk5 activity. Taken together, these data suggest that cdk5 phosphorylation of TH is an important regulator of TH activity through stabilization of TH protein levels.
Moy
Lily Y
LY
Department of Pathology and Howard Hughes Medical Institute, Harvard Medical School, Boston, Massachusetts 02115, USA. lily_moy@hms.harvard.edu
Tsai
Li-Huei
LH
D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D051360:Cyclin-Dependent Kinase 5; D018844:Cyclin-Dependent Kinases / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*; D004795:Enzyme Stability; D006801:Humans; D051379:Mice; D018345:Mice, Knockout; D008822:Mice, Transgenic; D008969:Molecular Sequence Data; D009419:Nerve Tissue Proteins / Q000378:metabolism; D009474:Neurons / Q000201:enzymology; D016716:PC12 Cells; D010766:Phosphorylation; D051381:Rats; D011993:Recombinant Fusion Proteins; D016415:Sequence Alignment; D012694:Serine / Q000378:metabolism*; D013329:Structure-Activity Relationship; D013378:Substantia Nigra / Q000201:enzymology; D014162:Transfection; D014446:Tyrosine 3-Monooxygenase / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*
D009419:Nerve Tissue Proteins; D011993:Recombinant Fusion Proteins; C089495:neuronal Cdk5 activator (p25-p35); D012694:Serine; D014446:Tyrosine 3-Monooxygenase; D051360:Cyclin-Dependent Kinase 5; C495905:CDK5 protein, human; C495906:Cdk5 protein, mouse; C495907:Cdk5 protein, rat; D018844:Cyclin-Dependent Kinases