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Published on: September 22, 2009
TGFbeta-Smad signalling in postoperative human lens epithelial cells
S Saika1, T Miyamoto, I Ishida
1Department of Ophthalmology, Wakayama Medical University, Japan. shizuya@wakayama-med.ac.jp
Aims:
To localise Smads3/4 proteins in lens epithelial cells (LECs) of fresh and postoperative human specimens. Smads3/4 are involved in signal transduction between transforming growth factor beta (TGFbeta) cell surface receptors and gene promoters. Nuclear localisation of Smads indicates achievement of endogenous TGFbeta signalling in cells.
Methods:
Three circular sections of the anterior capsule, one lens, and 17 capsules undergoing postoperative healing were studied. Immunohistochemistry was performed for Smads3/4 in paraffin sections of the specimens. The effect of exogenous TGFbeta2 on Smad3 subcellular localisation was examined in explant cultures of extracted human anterior lens epithelium.
Results:
The cytoplasm, but not the nuclei, of LECs of uninjured lenses was immunoreactive for Smads3/4. In contrast, nuclear immunoreactivity for Smads3/4 was detected in LECs during capsular healing. Nuclei positive for Smads3/4 were observed in monolayered LECs adjacent to the regenerated lens fibres of Sommerring's ring. Interestingly, the nuclei of LECs that were somewhat elongated, and appeared to be differentiating into fibre-like cells, were negative for Smads3/4. Fibroblast-like, spindle-shaped lens cells with nuclear immunoreactivity for nuclear Smads3/4 were occasionally observed in the extracellular matrix accumulated in capsular opacification. Exogenous TGFbeta induced nuclear translocation of Smad3 in LECs of anterior capsule specimens in explant culture.
Conclusions:
This is consistent with TGFbeta induced Smad signalling being involved in regulating the behaviour of LECs during wound healing after cataract surgery.
Insights
Smad3/4 proteins are found in the cytoplasm of healthy lens epithelial cells (LECs). Following cataract surgery, nuclear localization of Smad3/4 in LECs indicates transforming growth factor beta (TGFbeta) signaling is active during wound healing.
Area of Science:
- Ophthalmology
- Cell Biology
- Molecular Biology
Background:
- Smads3/4 proteins are key mediators in transforming growth factor beta (TGFbeta) signaling pathways.
- Nuclear localization of Smads signifies the activation of endogenous TGFbeta signaling within cells.
Purpose of the Study:
- To investigate the localization of Smads3/4 proteins in human lens epithelial cells (LECs) from fresh and post-operative specimens.
- To understand the role of Smad3/4 protein localization in LECs during wound healing after cataract surgery.
Main Methods:
- Immunohistochemistry was employed to detect Smads3/4 proteins in paraffin-embedded human anterior capsule and lens specimens.
- Explant cultures of human anterior lens epithelium were used to study the effect of exogenous TGFbeta2 on Smad3 subcellular localization.
Main Results:
- In uninjured lenses, Smads3/4 proteins were localized to the cytoplasm of LECs.
- During capsular healing post-surgery, nuclear immunoreactivity for Smads3/4 was observed in LECs.
- Exogenous TGFbeta stimulation induced nuclear translocation of Smad3 in LECs cultured in vitro.
Conclusions:
- The findings suggest that TGFbeta-induced Smad signaling plays a crucial role in regulating LEC behavior during the wound healing process after cataract surgery.
- Nuclear localization of Smads3/4 in LECs is a marker for active TGFbeta signaling during ocular wound repair.
