An increase in apoptosis and reduction in αB-crystallin expression levels in the lens underlie the cataractogenesis of Morioka cataract (MCT) mice

Abstract

We examined the morphological changes in fibers, localization of apoptotic cells, and protein expression of αB-crystallin in the lens of Morioka cataract (MCT) mice, a novel cataract model. Using a scanning electron microscope, swollen lens fibers and enlarged spaces between lens fibers were observed in the lens of 3-week-old MCT mice. At 2 weeks of age (before cataract), the single-strand DNA (ssDNA)-positive (indicating apoptosis) cell ratio of the lens epithelium was significantly higher in MCT than in wild-type ddY mice. At 2 and 4 weeks of age, αB-crystallin protein expression of the lens in MCT mice was significantly lower than that in wild-type ddY mice. These findings suggest that increase in apoptosis and reduction in αBcrystallin level are involved in the cataractogenesis of MCT mice.

Expression of transforming growth factor β and fibroblast growth factor 2 in the lens epithelium of Morioka cataract mice

“…In the present study, at 2 weeks after birth, the positive reaction of lens epithelial cells to anti-TGFβ in MCT mice was slightly stronger and the expression of TGFβ1 and TGFβ2 mRNA significantly higher than in agematched wild-type ddY mice. These results suggest that the elevated expression of TGFβ is involved in onset of cataractous histological changes since lens opacity appears at 6 to 8 weeks of age (Kondo et al 2010) and the swollen lens fiber is electron microscopically observed at 3 weeks after birth in the MCT mice (Kondo et al 2011). This notion is supported by the following reports: rats that receive a single intravitreal injection of TGFβ subsequently develop cataracts ; TGFβ stimula-tion induces lens epithelial cells to undergo aberrant growth and differentiation (Lovicu et al 2002).…”

“…) and the swollen lens fiber is electron microscopically observed at 3 weeks after birth in the MCT mice (Kondo et al. ). This notion is supported by the following reports: rats that receive a single intravitreal injection of TGFβ subsequently develop cataracts (Hales et al.…”

“…) and swollen lens fiber is electron microscopically observed at 3 weeks after birth (Kondo et al. ), and lens opacity appears at 6 to 8 weeks of age (Kondo et al. ).…”

“…Thus, the establishment of an animal model of cataracts will help elucidate the pathology underlying human cataractogenesis (Graw 2004). In the Morioka cataract (MCT) mice the cataract is inherited by an autosomal recessive manner (Kondo et al 2010) and swollen lens fiber is electron microscopically observed at 3 weeks after birth (Kondo et al 2011), and lens opacity appears at 6 to 8 weeks of age (Kondo et al 2010).…”