Purchase this article with an account.
Wiktor Stopka, Tom Libby, Eddie Wang, Chun-hong Xia, Xiaohua Gong; Lens Stiffness in Connexin Mutant Lenses. Invest. Ophthalmol. Vis. Sci. 2015;56(7 ):3559.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
Connexin Gja3 knockout mice displayed variable cataracts between the C57BL/6J (B6) strain and the 129SvJae (129) strain backgrounds. 129 wild-type (WT) mice lack lens beaded intermediate filaments and utilize a periaxin gene variance. Periaxin is a scaffold protein known to be important in the cytoskeleton of the lens fiber cells. The goal of this project is to test the hypothesis that gap junctions, beaded filaments, and a periaxin-mediated cytoskeleton synergistically regulate lens stiffness and nuclear cataract formation.
A modified muscle lever system has been established to measure the stiffness of mouse lenses from WT and connexin mutant mice. Lenses were compressed to a maximum of 2mN of force over 2 minutes. Displacement values at the point of maximum force were used in comparing the stiffness of lenses of differing age and genotype. Lenses of B6 WT, 129 WT, Gja3 connexin (Cx46 or α3) knockout (Gja3-/-) mice in both WT strain backgrounds, between 4 weeks to 48 weeks of age, were measured. 4-week old lenses from B6 a3+/- (comparable to B6 WT) with the 129 variant of periaxin, and 129 WT with the B6 variant of periaxin were also measured.
Results show that old 129 WT lenses were compressed 239.6µm +/- 28.8µm (n=14 lenses) while old 129 Gja3-/- lenses were only compressed 127.7µm +/- 22.5µm (n=7). Thus, the Gja3-/- lenses appear significantly stiffer than WT (p<0.01). A similar trend is seen in old B6 WT (177.7µm +/- 13.5, n=11) vs B6 Gja3-/- (129.4µm +/- 23.0µm, n=12) lenses (p<0.01). In young (4 weeks) lenses of 129 WT with B6 periaxin (364.4µm +/- 18.4µm, n=5), lenses appeared significantly softer when compared with young 129 WT (305.1µm +/- 20.8µm, n=6) (p<0.01). Alternatively, young B6 a3+/- with 129 periaxin (281.4µm +/- 15.6µm, n=7) appeared significantly stiffer compared to young B6 WT (328.4µm +/- 19.2µm, n=9) (p<0.01).
Both the presence of B6 periaxin and loss of CP49 appear to contribute to the softening of the lens, as can be seen in the 129 background with B6 periaxin lenses. On the other hand, the presence of 129 periaxin appears to stiffen the lens, as in the B6 a3+/- with 129 periaxin lenses. The loss of the Gja3 protein appears to stiffen the lens, in both young and old samples, but more drastically in older lenses. Perhaps, the loss of Gja3 protein affects the structures of fiber cell interdigitations, leading to impairment in the elasticity of the fiber cells resulting in lens hardening.
This PDF is available to Subscribers Only