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JY Lu, JR Kuszak, KJ Al-Ghoul; Localization of Basal Membrane Complex Components at Lens Sutures . Invest. Ophthalmol. Vis. Sci. 2002;43(13):457.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose:To localize specific components of the Basal Membrane Complex (BMC) in elongating lens fiber ends as they approach and form posterior suture branches. Methods:Normal, juvenile (4-6 week old) Sprague-Dawley rat lenses (n=24) were fixed immediately following enucleation, embedded in 2 % agar, then sectioned with a vibrating knife microtome. Three-four serial sections, 100µm thick, were cut parallel to the equatorial plane beginning at the posterior pole. F-actin was localized with phalloidin-FITC; myosin, beta-1 integrin and N-cadherin were localized by immunofluorescent techniques. Specimens were visualized on a laser scanning confocal microscope. Negative controls were performed to assure specificity of immuno-labeling. Results:As fibers approached the posterior suture branches, F-actin labeling was seen to be predominately localized to the periphery of the BMC. This was consistent with F-actin localization in more laterally-positioned fiber ends. At sutures, F-actin in the BMC was rearranged into numerous small profiles. Furthermore, in fibers which had detached from the capsule, a band of intense F-actin staining was noted adjacent to the sutures. Myosin was present in the BMC as a diffuse plaque which filled the fiber ends. Although beta-I integrin was also distributed throughout the BMC, it was overlain by instances of bright, punctate fluorescence. Directly adjacent to and at the suture branches, immuno-fluorescence for beta-1 integrin was markedly reduced. As expected, initial N-cadherin characterization showed a strong localization to the periphery of the BMC. Conclusion:F-actin and integrin components of the BMC undergo a major rearrangement in the final stages of migration and in detachment from the capsule to form suture branches. Further, the intense staining of F-actin in detached fibers adjacent to the sutures suggests that lens fibers may have a structure analogous to the terminal web of other epithelia.
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