RESUMO
CK1δ, a member of the casein kinase 1 family, is involved in the regulation of various cellular processes and has been associated with the pathophysiology of neurodegenerative diseases and cancer. Therefore recently, interest in generating highly specific inhibitors for personalized therapy has increased enormously. However, the efficacy of newly developed inhibitors is affected by the phosphorylation state of CK1δ. Cellular kinases phosphorylating CK1δ within its C-terminal domain have been identified but still more information regarding the role of site-specific phosphorylation in modulating the activity of CK1δ is required. Here we show that Chk1 phosphorylates rat CK1δ at serine residues 328, 331, 370, and threonine residue 397 as well as the human CK1δ transcription variants 1 and 2. CK1δ mutant proteins bearing one, two or three mutations at these identified phosphorylation sites exhibited significant differences in their kinetic properties compared to wild-type CK1δ. Additionally, CK1δ co-precipitates with Chk1 from HT1080 cell extracts and activation of cellular Chk1 resulted in a significant decrease in cellular CK1δ kinase activity. Taken together, these data point towards a possible regulatory relationship between Chk1 and CK1δ.
Assuntos
Caseína Quinase Idelta/genética , Fibroblastos/metabolismo , Regulação da Expressão Gênica , Proteínas Quinases/genética , Sequência de Aminoácidos , Animais , Caseína Quinase Idelta/metabolismo , Linhagem Celular Tumoral , Quinase 1 do Ponto de Checagem , Fibroblastos/citologia , Humanos , Dados de Sequência Molecular , Mutação , Fosforilação , Proteínas Quinases/metabolismo , Ratos , Proteínas Recombinantes de Fusão/genética , Proteínas Recombinantes de Fusão/metabolismo , Serina/genética , Serina/metabolismo , Transdução de Sinais , Treonina/genética , Treonina/metabolismoRESUMO
CK1delta, a member of the casein kinase 1 family of serine/threonine specific kinases, has been shown to be involved in the regulation of microtubule dynamics. We have now identified a 176 aa fragment of the light chain LC2 of MAP1A (termed LC2-P16) specifically interacting with CK1delta. Two CK1delta interacting domains of LC2 were identified, located between aa 2629 and 2753 close to aa 2683 and between aa 2712 and 2805 of LC2. The two regions necessary for the interaction of LC2 with CK1delta have been mapped between aa 76-103 and aa 351-375 of CK1delta. Furthermore, LC2 has been identified as a new substrate of CK1delta. We therefore propose a model in which CK1delta could modulate microtubule dynamics by changing the phosphorylation status of the light chain LC2 of MAP1A.
