Developmental truncations of connexin 50 by caspases adaptively regulate gap junctions/hemichannels and protect lens cells against ultraviolet radiation

Ke Wang, Sumin Gu, Xinye Yin, Susan E Weintraub, Zichun Hua, Jean X Jiang

Research output: Contribution to journalArticle

7 Citations (Scopus)

Abstract

The gap junction-forming connexin (Cx) 50 is truncated gradually during lens development. Premature cleavage of lens connexins is thought to be associated with cataract formation. We have shown previously that Cx50 is likely to be cleaved by caspase-3 like protease during chick lens development. Here, using HPLC-electrospray tandem mass spectrometry, we mapped two cleavage sites at the C terminus of Cx50 after Glu- 368 and Asp-379 and identified caspase-3 and caspase-1 as the responsible proteases, respectively. The activity of caspase-1, like caspase-3, was detected in the outer cortex increased during lens development, which coincided with the accumulation of the truncated fragments of Cx50 in the core region of the lens. The truncated Cx50 fragments present in older lenses were reproduced in the younger lens after treatment with UV radiation; this cleavage could be partially blocked by caspase-1/3-specific inhibitors. Interestingly, as compared with full-length Cx50, caspase-truncated Cx50 showed a dramatic decrease in gap junction coupling and a loss of hemichannel function. Furthermore, expression of caspase-truncated Cx50 fragments increased cell viability against UV radiation as compared with full-length Cx50. Together, these results suggest that both caspase-1 and -3 are responsible for the cleavage at the C terminus of Cx50 during lens development. The reduction of gap junction coupling and closure of hemichannels formed by truncated Cx50 are likely to adaptively protect cells against elevated oxidative stress associated with lens aging.

Original languageEnglish (US)
Pages (from-to)15786-15797
Number of pages12
JournalJournal of Biological Chemistry
Volume287
Issue number19
DOIs
StatePublished - May 4 2012

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Gap Junctions
Caspases
Ultraviolet radiation
Lenses
Radiation
Caspase 1
Caspase 3
Peptide Hydrolases
connexin 50
Connexins
Oxidative stress
Tandem Mass Spectrometry
Cataract
Mass spectrometry
Cell Survival
Oxidative Stress
Aging of materials
High Pressure Liquid Chromatography
Cells

ASJC Scopus subject areas

  • Biochemistry
  • Cell Biology
  • Molecular Biology

Cite this

Developmental truncations of connexin 50 by caspases adaptively regulate gap junctions/hemichannels and protect lens cells against ultraviolet radiation. / Wang, Ke; Gu, Sumin; Yin, Xinye; Weintraub, Susan E; Hua, Zichun; Jiang, Jean X.

In: Journal of Biological Chemistry, Vol. 287, No. 19, 04.05.2012, p. 15786-15797.

Research output: Contribution to journalArticle

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