Protein kinases that regulate chromosome stability and their downstream targets.
Upon genotoxic stress, checkpoint machinery in eukaryotic cells induces cell-cycle arrest, thus allowing the cells to repair damaged DNA or stalled replication forks. The checkpoint machinery is mediated by phosphorylation cascades involving protein kinases and their target proteins. Since the genome is under constant threat from DNA damage due to radiation, chemicals and replication errors, checkpoint dysregulation can cause catastrophic DNA damage, resulting in chromosome instability, aneuploidy, and even tumorigenesis. Two parallel pathways that respond to DNA-damage stress have been extensively studied. The first is the ATM pathway, which responds to double-stranded DNA breaks, while the second is the ATR pathway, which primarily responds to agents that interfere with normal DNA replication. The ATM and ATR kinases activate their downstream target proteins by phosphorylating specific serine or threonine residues. Dephosphorylation by protein phosphatase (PP2A) also participates in the regulation of these phosphorylation signals. Of the target proteins, the two effector kinases CHK1 and CHK2 are particularly important because they phosphorylate additional substrates to maintain chromosome stability after various DNA damaging insults. Recent observations indicate that other protein kinases that control centrosome duplication and chromosome segregation during the cell cycle also play essential roles in maintaining genomic stability.
Nojima
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Department of Molecular Genetics, Research Institute for Microbial Diseases, Osaka University, Osaka, Japan.
D064007:Ataxia Telangiectasia Mutated Proteins; D018797:Cell Cycle Proteins / Q000378:metabolism; D000071877:Checkpoint Kinase 1; D064447:Checkpoint Kinase 2; D043171:Chromosomal Instability; D004249:DNA Damage; D004268:DNA-Binding Proteins / Q000378:metabolism; D004789:Enzyme Activation; D015971:Gene Expression Regulation, Enzymologic; D016678:Genome; D006801:Humans; D008954:Models, Biological; D009153:Mutagens; D010766:Phosphorylation; D011494:Protein Kinases / Q000235:genetics* / Q000378:metabolism; D054648:Protein Phosphatase 2 / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D025521:Tumor Suppressor Proteins / Q000378:metabolism
D018797:Cell Cycle Proteins; D004268:DNA-Binding Proteins; D009153:Mutagens; D025521:Tumor Suppressor Proteins; D011494:Protein Kinases; D064447:Checkpoint Kinase 2; C576324:ATM protein, human; C576597:ATR protein, human; D064007:Ataxia Telangiectasia Mutated Proteins; C000605867:CHEK1 protein, human; C578634:CHEK2 protein, human; D000071877:Checkpoint Kinase 1; D017346:Protein Serine-Threonine Kinases; D054648:Protein Phosphatase 2