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MAPKs and Mst1/Caspase-3 pathways contribute to H2B phosphorylation during UVB-induced apoptosis

ChengRong Lu1, Ying Shi, Yuan Luo

  • 1Aviation Medicine Research Laborabory, General Hospital of Air Force, Beijing, 100142, China. luchengrong@263.net

Science China. Life Sciences
|July 6, 2010
PubMed

Insights

Programmed cell death (apoptosis) involves histone modification. Ultraviolet B light (UVB) triggers H2B phosphorylation at Ser14 via MAPKs and caspase-3/Mst1 pathways, leading to chromatin condensation during apoptosis.

Area of Science:

  • Cell Biology
  • Molecular Biology
  • Biochemistry

Background:

  • Apoptosis, or programmed cell death, is a fundamental biological process in eukaryotes.
  • Histone modifications, particularly H2B phosphorylation at serine 14 (Ser14), are implicated in nuclear events during apoptosis.
  • Mst1 kinase is known to catalyze H2B (Ser14) phosphorylation, linking it to chromatin condensation.

Purpose of the Study:

  • To investigate the molecular mechanisms regulating H2B (Ser14) phosphorylation during ultraviolet B (UVB)-induced apoptosis.
  • To determine the roles of MAPKs (ERK1/2, JNK1/2, p38), Mst1, and caspase-3 in this process.

Main Methods:

  • UVB irradiation of cells to induce apoptosis.
  • Analysis of MAPK activation (ERK1/2, JNK1/2, p38).
  • Assessment of H2B phosphorylation (Ser14) and acetylation.
  • Enzyme activity assays for Mst1 and caspase-3.
  • Inhibition studies using specific kinase inhibitors and caspase inhibitors.

Main Results:

  • UVB exposure activated MAPKs (ERK1/2, JNK1/2, p38) and induced H2B (Ser14) phosphorylation in a time-dependent manner.
  • Inhibition of MAPKs abrogated UVB-induced H2B (Ser14) phosphorylation.
  • UVB activated caspase-3, which in turn regulated Mst1 activity, leading to H2B (Ser14) phosphorylation and chromatin condensation.
  • Complete caspase-3 inhibition partially reduced Mst1 activation and H2B (Ser14) phosphorylation without affecting MAPK activity.

Conclusions:

  • H2B (Ser14) phosphorylation during UVB-induced apoptosis is a coordinated event regulated by both MAPK signaling pathways and the caspase-3/Mst1 cascade.
  • These pathways converge to control histone modifications essential for chromatin condensation and apoptotic execution.

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