Abstract
Purpose :
To test a hypothesis that Periaxin (Prx) gene variant of 129 mouse strain background acts as a gain-of-function variant to facilitate severe nuclear cataract in connexin 46 knockout (Cx46KO) lenses by characterizing Prx-Cx46 double knockout (DKO) lens phenotypes. To determine the underlying cellular mechanism for functional association between connexin 46 and periaxin in lens homeostasis, stiffness and cataract formation.
Methods :
Biochemical approaches including western blotting and morphological tools including laser confocal microscopic imaging were used to characterize and compare the molecular and cellular changes among lenses of wild-type, Cx46KO at different strain backgrounds and the Prx-Cx46 DKO mice in vivo. Prx gene variances were characterized in cultured cells in vitro.
Results :
Severe nuclear cataracts in Cx46KO lenses were associated with the presence of highly expressed 129-periaxin proteins that were colocalized with F-actin in protrusions in lens fiber cells. The presence of 129-periaxin appeared to be associated with increased lens stiffness. Prx-Cx46 DKO at 129 strain background developed mild cataract that was similar to mild cataract in Cx46KO at C57BL/6J background, which expressed a low level of Prx variant in lens fibers.
Conclusions :
Mild cataracts in DKO lenses suggest that a loss of periaxin significantly attenuate the development of severe nuclear cataracts in Cx46KO lenses at 129 strain background and 129-Prx gene acts as a gain-of-function variant to facilitate cataractogenesis caused by increased calcium levels in Cx46KO lenses. This result further indicates that both Cx46-mediated cell communication and Prx-mediated membrane-cytoskeletal complex regulate the calcium homeostasis in the lens fibers.
This abstract was presented at the 2022 ARVO Annual Meeting, held in Denver, CO, May 1-4, 2022, and virtually.