Abstract
Abstract: :
Purpose:We have reported transient nuclear trasnlocation of Smads3/4 and up-regulation of AP-1 in healing, injured, lens epithelium (Saika et al. Exp. Eye Res. 72, 679-686; 2001; Shirai et al. Exp. Eye Res. 73, 461-468; 2001). To determine whether endogenous TGFß is regulating human lens cell behavior during repair after cataract extraction, we localized Smad proteins in human post-operative healing capsules. Methods:Three circular sections of the anterior capsule, one crystalline lens and seventeen capsules undergoing postoperative healing were studied. Paraffin sections were immunostained for Smads3/4. Expression of a-smooth muscle actin was also examined. Lens cell differentiation was examined by beta-crystalline expression. Results:Epithelial cells of uninjured crystalline lenses stained for Smads3/4 in the cytoplasm, but not in nuclei. Nuclei of epithelial cells lining the anterior capsular sections were also unstained. Nuclear Smads3/4 staining was then detected in lens cells during capsular healing. Nuclei positive for Smads3/4 were observed in monolayer lens epithelial cells adjacent to the regenerated lens fibers of Sommerring's ring. Interestingly, the nuclei of lens cells somewhat elongated, presumably initiated to differentiate into fiber cells expression ß-crystalline, were negative for Smads3/4. Fibroblast-like, spindle-shaped lens cells with nuclear immunoreactivity for nuclear Smads3/4 were occasionally observed in extracellular matrix accumulation. Especially, such cells with nuclear Smads3/4 were prominent in the fibrous tissue adjacent to the optic portion of the IOL. Conclusion:Endogenous TGFß is thought to regulate lens epithelial cells behaviors. Lens cells under differentiation toward regenerated fiber cells might be escaping TGFß-Smads3/4 signaling.
Keywords: 423 growth factors/growth factor receptors • 631 wound healing • 580 signal transduction