Purchase this article with an account.
D. A. Scheiblin, V. N. Smirskii, K. J. Czymmek, M. K. Duncan; The Function of β1 Integrin on the Lateral Membranes of Lens Fiber Cells. Invest. Ophthalmol. Vis. Sci. 2010;51(13):6359.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
Previous work has shown that the lack of β1 integrin in the embryonic lens causes epithelial-mesenchymal transition of the lens epithelium followed by apoptosis. While lens fiber cells are also defective, it is unknown whether these defects arise secondarily due to the loss of the epithelial cells or reflect an important primary role for β1 integrin in the fibers. This work investigates the role of β1 integrin in lens fiber cells.
Mice homozygous for the β1 integrin floxed allele were bred with mice carrying the MLR39 Cre gene expressed only in lens fiber cells. Immunofluorescence and PCR was assessed to determine the deletion of the gene. The clarity of lenses that lacked β1 integrin and C57Bl/6 wildtype controls were assessed by darkfield microscopy. Lens ultrastructure was assessed using scanning electron microscopy (SEM).
The conditional deletion of β1 integrin resulted in the removal of exon 3 of the gene causing premature translational termination at amino acid 57. Mice lacking β1 integrin in lens fiber cells had variable phenotypes ranging from severe cataract to a grossly transparent, clear lens. Irrespective of gross phenotype, the vertices of the cortical fiber cell lateral membranes lacking β1 integrin had disordered ball and socket structures instead of the highly regular structural repeats of wildtype lens fibers. This became progressively more severe in older cortical fibers, which exhibit ball and sockets of variable width and extension from the cell. Finally, nuclear fibers lacking b1-integrin completely lack ball and sockets and instead have smooth lateral membranes. In wildtype lenses, membrane furrows were found in a random pattern on the lateral sides of nuclear fibers. In contrast, the membrane furrows in nuclear fibers lacking β1 integrin were of higher density, had more pronounced ridges and were highly organized into a lattice-like geometric pattern.
The function of β1 integrin protein is required to form the appropriate morphology of lens fiber cell lateral membranes.
This PDF is available to Subscribers Only