p35/cdk5 binds and phosphorylates beta-catenin and regulates beta-catenin/presenilin-1 interaction.
The neuronal cyclin-dependent kinase p35/cdk5 comprises a catalytic subunit (cdk5) and an activator subunit (p35). To identify novel p35/cdk5 substrates, we utilized the yeast two-hybrid system to screen for human p35 binding partners. From one such screen, we identified beta-catenin as an interacting protein. Confirmation that p35 binds to beta-catenin was obtained by using glutathione S-transferase (GST)-beta-catenin fusion proteins that interacted with both endogenous and transfected p35, and by showing that beta-catenin was present in p35 immunoprecipitates. p35 and beta-catenin also displayed overlapping subcellular distribution patterns in cells including neurons. Finally, we demonstrated that p35/cdk5 phosphorylates beta-catenin. beta-catenin also binds to presenilin-1 and altered beta-catenin/presenilin-1 interactions may be mechanistic in Alzheimer's disease (AD). Abnormal p35/cdk5 activity has also been suggested to contribute to AD. We therefore investigated how modulation of p35/cdk5 activity influenced beta-catenin/presenilin-1 interactions. Inhibition of p35/cdk5 with roscovitine did not alter the steady state levels of either beta-catenin or presenilin-1 but reduced the amount of presenilin-1 bound to beta-catenin. Thus, p35/cdk5 binds and phosphorylates beta-catenin and regulates its binding to presenilin-1. The findings reported here therefore provide a novel molecular framework to connect p35/cdk5 with beta-catenin and presenilin-1 in AD.
Kesavapany
S
S
Department of Neuroscience, The Institute of Psychiatry, Denmark Hill, London SE5 8AF, UK.
Lau
K F
KF
McLoughlin
D M
DM
Brownlees
J
J
Ackerley
S
S
Leigh
P N
PN
Shaw
C E
CE
Miller
C C
CC
D000544:Alzheimer Disease / Q000378:metabolism; D000818:Animals; D016466:CHO Cells; D002154:Calpain / Q000378:metabolism; D002540:Cerebral Cortex / Q000166:cytology; D006224:Cricetinae; D051360:Cyclin-Dependent Kinase 5; D018844:Cyclin-Dependent Kinases / Q000378:metabolism*; D003598:Cytoskeletal Proteins / Q000378:metabolism*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006801:Humans; D007668:Kidney / Q000166:cytology; D008565:Membrane Proteins / Q000378:metabolism*; D009410:Nerve Degeneration / Q000378:metabolism; D009419:Nerve Tissue Proteins / Q000378:metabolism*; D010766:Phosphorylation; D053764:Presenilin-1; D011485:Protein Binding / Q000187:drug effects / Q000502:physiology; D011687:Purines / Q000494:pharmacology; D051381:Rats; D000077546:Roscovitine; D015534:Trans-Activators; D051176:beta Catenin
C495270:CTNNB1 protein, human; C495268:Ctnnb1 protein, rat; D003598:Cytoskeletal Proteins; D004791:Enzyme Inhibitors; D008565:Membrane Proteins; D009419:Nerve Tissue Proteins; C508853:PSEN1 protein, human; D053764:Presenilin-1; D011687:Purines; D015534:Trans-Activators; D051176:beta Catenin; C089495:neuronal Cdk5 activator (p25-p35); D000077546:Roscovitine; D051360:Cyclin-Dependent Kinase 5; C495905:CDK5 protein, human; C495907:Cdk5 protein, rat; D018844:Cyclin-Dependent Kinases; D002154:Calpain