Purchase this article with an account.
Q Yan, D Blake, T Wight, JI Clark, EH Sage; Compromised Permeability of the Lens Capsule Contributes to Cataract Formation in SPARC-null Mice . Invest. Ophthalmol. Vis. Sci. 2002;43(13):4001.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
Purpose: To investigate the role of SPARC (secreted protein acidic and rich in cysteine) in the structural integrity of the lens capsule, and in the expression and organization of lens capsular extracellular matrix (ECM). Methods: Lens morphology was studied by light and electron microscopy (EM). Lens capsule permeability was analyzed by dye penetration of the lens. Lens fiber cell proteins were analyzed by SDS-PAGE. Lens capsular ECM proteins were identified by immunohistochemistry and immunoblotting. Results: Cortical opacification of SPARC-null lenses begins at 1 month after birth when a few lens secondary fiber cells exhibit a swollen shape. By 3 months, all the secondary fibers lose their hexagonal profile and become swollen. By SDS-PAGE, the profile of fiber proteins of the SPARC-null lens is similar to that of the wild-type lens at 3 months; inappropriate enzymatic activity in SPARC-null cells therefore appears minimal. EM revealed that lens fiber cells at the bow region protrude into the posterior lens capsule and disrupt the structural integrity of the lens as early as 1 month of age. Increased permeability of the lens capsule in SPARC-null lenses was demonstrated by penetration of trypan blue into the lens. Furthermore, the expression and organization of laminin 1 and perlecan were altered in SPARC-null lenses. Conclusion: Compromised permeability of the lens capsule could alter the osmotic balance in the fiber cells in SPARC-null lenses and could lead to the entry of water into the cells. Alterations in the levels and distribution of capsular ECM in the SPARC-null lens are likely to compromise its structural integrity and cellular functions. We propose that increased permeability is a major component of cataractogenesis in SPARC-null mice. Supported by EY13180, and F32EY06987 to QY.
This PDF is available to Subscribers Only