A Noncatalytic Domain of Glycogen Synthase Kinase-3 (GSK-3) Is Essential for Activity |
| |
Authors: | Jessica L Buescher and Christopher J Phiel |
| |
Institution: | From the ‡Integrated Biomedical Science Graduate Program, College of Medicine, The Ohio State University, Columbus, Ohio 43210 and ;the §Center for Molecular and Human Genetics, The Research Institute at Nationwide Children''s Hospital, Columbus, Ohio 43205 |
| |
Abstract: | Glycogen synthase kinase-3 (GSK-3) isoforms, GSK-3α and GSK-3β, are serine/threonine kinases involved in numerous cellular processes and diverse diseases, including Alzheimer disease, cancer, and diabetes. GSK-3 isoforms function redundantly in some settings, while, in others, they exhibit distinct activities. Despite intensive investigation into the physiological roles of GSK-3 isoforms, the basis for their differential activities remains unresolved. A more comprehensive understanding of the mechanistic basis for GSK-3 isoform-specific functions could lead to the development of isoform-specific inhibitors. Here, we describe a structure-function analysis of GSK-3α and GSK-3β in mammalian cells. We deleted the noncatalytic N and C termini in both GSK-3 isoforms and generated point mutations of key regulatory residues. We examined the effect of these mutations on GSK-3 activity toward Tau, activity in Wnt signaling, interaction with Axin, and GSK-3α/β Tyr279/216 phosphorylation. We found that the N termini of both GSK-3 isoforms were dispensable, whereas progressive C-terminal deletions resulted in protein misfolding exhibited by deficient activity, impaired ability to interact with Axin, and a loss of Tyr279/216 phosphorylation. Our data predict that small molecules targeting the divergent C terminus may lead to isoform-specific GSK-3 inhibition through destabilization of the GSK-3 structure. |
| |
Keywords: | Enzyme Structure Neurodegeneration Phosphorylation Enzymes Signal Transduction Wnt Pathway |
|
|