Abstract
The cellular response to DNA damage is mediated by evolutionarily conserved Ser/Thr kinases, phosphorylation of Cdc25 protein phosphatases, binding to 14-3-3 proteins, and exit from the cell cycle. To investigate DNA damage responses mediated by the p38/stress-activated protein kinase (SAPK) axis of signaling, the optimal phosphorylation motifs of mammalian p38alpha SAPK and MAPKAP kinase-2 were determined. The optimal substrate motif for MAPKAP kinase-2, but not for p38 SAPK, closely matches the 14-3-3 binding site on Cdc25B/C. We show that MAPKAP kinase-2 is directly responsible for Cdc25B/C phosphorylation and 14-3-3 binding in vitro and in response to UV-induced DNA damage within mammalian cells. Downregulation of MAPKAP kinase-2 eliminates DNA damage-induced G2/M, G1, and intra S phase checkpoints. We propose that MAPKAP kinase-2 is a new member of the DNA damage checkpoint kinase family that functions in parallel with Chk1 and Chk2 to integrate DNA damage signaling responses and cell cycle arrest in mammalian cells.
Publication types
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Research Support, Non-U.S. Gov't
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Research Support, U.S. Gov't, P.H.S.
MeSH terms
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14-3-3 Proteins / genetics
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14-3-3 Proteins / metabolism
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Amino Acid Motifs
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Amino Acid Sequence
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Apoptosis
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Base Sequence
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Catalytic Domain
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Cell Cycle / physiology*
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Cell Cycle / radiation effects*
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Cell Cycle Proteins / genetics
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Cell Cycle Proteins / metabolism
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Cell Line
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DNA Damage
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Humans
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In Vitro Techniques
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Intracellular Signaling Peptides and Proteins
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Models, Biological
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Models, Molecular
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Phosphorylation
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Protein Kinases / chemistry
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Protein Kinases / genetics
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Protein Kinases / metabolism*
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Protein Serine-Threonine Kinases
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RNA, Small Interfering / genetics
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Recombinant Fusion Proteins / chemistry
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Recombinant Fusion Proteins / genetics
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Recombinant Fusion Proteins / metabolism
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Static Electricity
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Ultraviolet Rays
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cdc25 Phosphatases / genetics
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cdc25 Phosphatases / metabolism
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p38 Mitogen-Activated Protein Kinases / chemistry
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p38 Mitogen-Activated Protein Kinases / genetics
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p38 Mitogen-Activated Protein Kinases / metabolism
Substances
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14-3-3 Proteins
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Cell Cycle Proteins
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Intracellular Signaling Peptides and Proteins
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RNA, Small Interfering
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Recombinant Fusion Proteins
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Protein Kinases
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MAP-kinase-activated kinase 2
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Protein Serine-Threonine Kinases
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p38 Mitogen-Activated Protein Kinases
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CDC25B protein, human
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CDC25C protein, human
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cdc25 Phosphatases