DNA damage activates a spatially distinct late cytoplasmic cell-cycle checkpoint network controlled by MK2-mediated RNA stabilization

Mol Cell. 2010 Oct 8;40(1):34-49. doi: 10.1016/j.molcel.2010.09.018.

Abstract

Following genotoxic stress, cells activate a complex kinase-based signaling network to arrest the cell cycle and initiate DNA repair. p53-defective tumor cells rewire their checkpoint response and become dependent on the p38/MK2 pathway for survival after DNA damage, despite a functional ATR-Chk1 pathway. We used functional genetics to dissect the contributions of Chk1 and MK2 to checkpoint control. We show that nuclear Chk1 activity is essential to establish a G(2)/M checkpoint, while cytoplasmic MK2 activity is critical for prolonged checkpoint maintenance through a process of posttranscriptional mRNA stabilization. Following DNA damage, the p38/MK2 complex relocalizes from nucleus to cytoplasm where MK2 phosphorylates hnRNPA0, to stabilize Gadd45α mRNA, while p38 phosphorylates and releases the translational inhibitor TIAR. In addition, MK2 phosphorylates PARN, blocking Gadd45α mRNA degradation. Gadd45α functions within a positive feedback loop, sustaining the MK2-dependent cytoplasmic sequestration of Cdc25B/C to block mitotic entry in the presence of unrepaired DNA damage. Our findings demonstrate a critical role for the MK2 pathway in the posttranscriptional regulation of gene expression as part of the DNA damage response in cancer cells.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • 3' Untranslated Regions
  • Active Transport, Cell Nucleus
  • Antibiotics, Antineoplastic / pharmacology
  • Cell Cycle Proteins / genetics*
  • Cell Cycle* / drug effects
  • Cell Cycle* / genetics
  • Cell Cycle* / radiation effects
  • Cell Nucleus / enzymology
  • Checkpoint Kinase 1
  • Cytoplasm / enzymology*
  • DNA Damage*
  • DNA Repair
  • Doxorubicin / pharmacology
  • Exoribonucleases / metabolism
  • Feedback, Physiological
  • HeLa Cells
  • Head and Neck Neoplasms / enzymology
  • Head and Neck Neoplasms / genetics
  • Heterogeneous-Nuclear Ribonucleoproteins / metabolism
  • Humans
  • Intracellular Signaling Peptides and Proteins / genetics
  • Intracellular Signaling Peptides and Proteins / metabolism*
  • Mitosis
  • Nuclear Proteins / genetics*
  • Phosphorylation
  • Protein Kinases / metabolism
  • Protein-Serine-Threonine Kinases / genetics
  • Protein-Serine-Threonine Kinases / metabolism*
  • RNA Interference
  • RNA Processing, Post-Transcriptional* / drug effects
  • RNA Processing, Post-Transcriptional* / radiation effects
  • RNA Stability* / drug effects
  • RNA Stability* / radiation effects
  • RNA, Messenger / metabolism*
  • RNA-Binding Proteins / metabolism
  • Signal Transduction
  • Time Factors
  • Transfection
  • Ultraviolet Rays
  • cdc25 Phosphatases / metabolism
  • p38 Mitogen-Activated Protein Kinases / metabolism

Substances

  • 3' Untranslated Regions
  • Antibiotics, Antineoplastic
  • Cell Cycle Proteins
  • GADD45A protein, human
  • HNRNPA0 protein, human
  • Heterogeneous-Nuclear Ribonucleoproteins
  • Intracellular Signaling Peptides and Proteins
  • Nuclear Proteins
  • RNA, Messenger
  • RNA-Binding Proteins
  • TIAL1 protein, human
  • Doxorubicin
  • Protein Kinases
  • MAP-kinase-activated kinase 2
  • CHEK1 protein, human
  • Checkpoint Kinase 1
  • Protein-Serine-Threonine Kinases
  • p38 Mitogen-Activated Protein Kinases
  • Exoribonucleases
  • poly(A)-specific ribonuclease
  • CDC25B protein, human
  • CDC25C protein, human
  • cdc25 Phosphatases