Autoregulatory Mechanisms of Phosphorylation of Checkpoint Kinase 1
| Autor: | Xiangzi Han, Youwei Zhang, Jingna Wang |
|---|---|
| Rok vydání: | 2012 |
| Předmět: |
Cancer Research
animal structures genetic processes Cell Cycle Proteins Ataxia Telangiectasia Mutated Proteins Protein Serine-Threonine Kinases environment and public health Article Phosphorylation cascade MAP2K7 Catalytic Domain Cell Line Tumor Serine Homeostasis Humans Point Mutation Protein Interaction Domains and Motifs Protein phosphorylation CHEK1 Phosphorylation DNA-PKcs Cell Proliferation biology Cyclin-dependent kinase 2 G2-M DNA damage checkpoint Cell biology enzymes and coenzymes (carbohydrates) HEK293 Cells Oncology Checkpoint Kinase 1 biology.protein Cancer research biological phenomena cell phenomena and immunity Protein Kinases Protein Processing Post-Translational HeLa Cells |
| Zdroj: | Cancer Research. 72:3786-3794 |
| ISSN: | 1538-7445 0008-5472 |
| DOI: | 10.1158/0008-5472.can-12-0523 |
| Popis: | Checkpoint kinase 1 (Chk1), a serine/threonine protein kinase, is centrally involved in cell-cycle checkpoints and cellular response to DNA damage. Phosphorylation of Chk1 at 2 Ser/Gln (SQ) sites, Ser-317 and Ser-345, by the upstream kinase ATR is critical for checkpoint activation. However, the precise molecular mechanisms controlling Chk1 phosphorylation and subsequent checkpoint activation are not well understood. Here, we report unique autoregulatory mechanisms that control protein phosphorylation of human Chk1, as well as checkpoint activation and cell viability. Phosphorylation of Ser-317 is required, but not sufficient, for maximal phosphorylation at Ser-345. The N-terminal kinase domain of Chk1 prevents Chk1 phosphorylation at the C-terminus by ATR in the absence of DNA damage. Loss of the inhibitory effect imposed by the N-terminus causes constitutive phosphorylation of Chk1 by ATR under normal growth conditions, which in turn triggers artificial checkpoints that suppress the S-phase progression. Furthermore, two point mutations were identified that rendered Chk1 constitutively active, and expression of the constitutively active mutant form of Chk1 inhibited cancer cell proliferation. Our findings therefore reveal unique regulatory mechanisms of Chk1 phosphorylation and suggest that expression of constitutively active Chk1 may represent a novel strategy to suppress tumor growth. Cancer Res; 72(15); 3786–94. ©2012 AACR. |
| Databáze: | OpenAIRE |
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