Proteolytic cleavage and activation of PAK2 during UV irradiation- induced apoptosis in A431 cells

Tswen Kei Tang, Wen Chang Chang, Wen Hsiung Chan, Shiaw Der Yang, Mei Hui Ni, Jau Song Yu

Research output: Contribution to journalArticlepeer-review

42 Citations (Scopus)


Exposure of mammalian cells to ultraviolet (UV) light elicits a cellular response and can also lead to apoptotic cell death. In this report, we show that a 36-kDa myelin basic protein (MBP) kinase detected by an in-gel kinase assay can be dramatically activated during the early stages of UV irradiation-triggered apoptosis of A431 cells. Immunoblot analysis revealed that this 36-kDa MBP kinase could be recognized by an antibody against the C- terminal regions of a family of p21(Cdc42/Rac)-activated kinases (PAKs). By using this antibody and a PAK2-specific antibody against the N-terminal region of PAK2 as studying tools, we further demonstrated that UV irradiation caused cleavage of PAK2 to generate a 36-kDa C-terminal catalytic fragment and a 30-kDa N-terminal fragment in A431 cells. The appearance of the 36-kDa C-terminal catalytic fragment of PAK2 matched exactly with the activation of the 36-kDa MBP kinase in A431 cells upon UV irradiation. In addition, UV irradiation also led to activation of CPP32/caspase-3, but not ICH- 1L/caspase-2 and ICE/caspase-1, in A431 cells and the kinetics of activation of CPP32/caspase-3 appeared to correlate well with that of DNA fragmentation and of cleavage/activation of PAK2, respectively. Moreover, blockage of activation of CPP32/caspase-3 by pretreating the cells with two specific tetrapeptidic inhibitors for caspases (Ac-DEVD-cho and Ac-YVAD-cmk) could significantly attenuate the extent of cleavage/activation of PAK2 induced by UV irradiation. Collectively, the results demonstrate that cleavage and activation of PAK2 can be induced during the early stages of UV irradiation- triggered apoptosis and indicate the involvement of CPP32/caspase-3 in this process.

Original languageEnglish
Pages (from-to)442-454
Number of pages13
JournalJournal of Cellular Biochemistry
Issue number4
Publication statusPublished - Sept 15 1998
Externally publishedYes


  • A431 cells
  • Apoptosis
  • CPP32/caspase-3
  • PAK2
  • UV irradiation

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology


Dive into the research topics of 'Proteolytic cleavage and activation of PAK2 during UV irradiation- induced apoptosis in A431 cells'. Together they form a unique fingerprint.

Cite this