Glycogen synthase kinase-3beta regulates cyclin D1 proteolysis and subcellular localization

Article Abstract:

Glycogen synthase kinase-3beta (GSK-3beta) phosphorylates cyclin D1 on the carboxyl terminus (Thr-286) specifically and by doing so triggers rapid cyclin D1 turnover. Activity of GSK-3beta can be held back by signaling along a pathway that sequentially involves phosphatidylinositol-3-OH kinase (PI3K), Ras, and protein kinase B (Akt). The turnover of cyclin D1 is Ras dependent as its assembly is and mitogen regulated as a result. Proteolytic turnover and phosphorylation of cyclin D1 and its subcellular localization in cell division are connected by activity of GSK-3beta.

Observations, Cellular signal transduction, Genetic regulation, Genetic transcription, Transcription (Genetics), Cell nuclei, Cell nucleus, Proteolysis, Molecular genetics

Structural basis of inhibition of CDK-cyclin complexes by INK4 inhibitors

Article Abstract:

Results reveal that INK4 inhibitor binding to the cyclin-dependent kinases 4 and 6 weakens the affinity of D-type cyclins to the enzyme as shown by the enzyme-cyclin-inhibitor complex crystal structure analysis. Data point out that the inhibition results from distortion of the ATP binding site and misalignment of catalytic residues.

Statistical Data Included, Analysis, Crystals, Crystal structure, Structure-activity relationships (Biochemistry), Binding sites (Biochemistry), Active sites (Biochemistry)

Phosphorylation-dependent regulation of cyclin D1 nuclear export and cyclin D1-dependent cellular transformation

Article Abstract:

Results show that cyclin D1 transport from nucleus to cytoplasm during S phase of cell cycle is mediated by CRM1 nuclear exporting protein. Data further indicate that nuclear export activation of cyclin D1 occurs via threonine-286 phosphorylation, which in turn favors D1-CRMI complex formation.

Biological transport, Active, Active biological transport, Physiological regulation, Phosphorylation