Cell type-specific activation of intracellular transglutaminase 2 by oxidative stress or ultraviolet irradiation: Implications of transglutaminase 2 in age-related cataractogenesis

Dong Myung Shin, Ju Hong Jeon, Chai Wan Kim, Sung Yup Cho, Joon Cheol Kwon, Hye Jin Lee, Kyung Ho Choi, Sang Chul Park, In Gyu Kim

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Transglutaminase (TGase) 2 is a ubiquitously expressed enzyme that modifies proteins by cross-linking or polyamination. An aberrant activity of TGase 2 has implicated its possible roles in a variety of diseases including age-related cataracts. However, the molecular mechanism by which TGase 2 is activated has not been elucidated. In this report, we showed that oxidative stress or UV irradiation elevates in situ TGase 2 activity. Neither the expression level nor the in vitro activity of TGase 2 appeared to correlate with the observed elevation of in situ TGase 2 activity. Screening a number of cell lines revealed that the level of TGase 2 activation depends on the cell type and also the environmental stress, suggesting that unrecognized cellular factor(s) may specifically regulate in situ TGase 2 activity. Concomitantly, we observed that human lens epithelial cells (HLE-B3) exhibited about 3-fold increase in in situ TGase 2 activity in response to the stresses. The activated TGase 2 catalyzed the formation of water-insoluble dimers or polymers of αB-crystallin, βB2-crystallin, and vimentin in HLE-B3 cells, providing evidence that TGase 2 may play a role in cataractogenesis. Thus, our findings indicate that in situ TGase 2 activity must be evaluated instead of in vitro activity to study the regulation mechanism and function of TGase 2 in biological and pathological processes.

Original languageEnglish (US)
Pages (from-to)15032-15039
Number of pages8
JournalJournal of Biological Chemistry
Issue number15
StatePublished - Apr 9 2004


ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

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