Establishment of lens opacity model in Grx2 knockout mice based on CRISPR/cas9 system and the role of Grx2 in the pathogenesis of cataract / 中华实验眼科杂志

ABSTRACT

Objective:To explore the role of Grx2 in the pathogenesis of cataract by establishing Grx2 knockout (KO) and knockin (KI) mouse models. Methods:Ten black C57BL/6J mice were selected to make Grx2 KO model ( n=5) and Grx2 KI model ( n=5) using CRISPR/Cas9 system.The offspring mice were sequenced by tail clipping and included in the corresponding experimental group according to the genotype.The general condition and lens opacity was recorded.After the mice were sacrificed, the pathological changes of lens were observed by hematoxylin-eosin staining.The contents of reactive oxygen species (ROS) and 8-hydroxy-desoxyguanosine (8-OHdG) were analyzed by enzyme-linked immunosorbent assay (ELISA).The relative expression levels of Grx2, glutathione (GSH), B-cell lymphoma-2 (Bcl-2) , glutathione disulfide (GSSG) and Bcl-2-associated X protein (Bax) in mice lens were assayed.The use and feeding of experimental animals were in accordance with the Regulations on the Management of Experimental Animals issued by the State Science and Technology Commission.The study protocol was approved by the Ethics Committee of the Second Affiliated Hospital of Chongqing Medical University (No.2020-125). Results:The offspring of Grx2 KO and Grx2 KI homozygous and heterozygous mice were confirmed by tail cutting nested PCR and gene sequencing.Compared with the wild type (WT) mice of same age, the lens opacity of Grx2 KO heterozygous mice occurred earlier, while the lens of Grx2 KI homozygous mice remained transparent all the time.A large number of gaps and vacuoles were found in the lens fibers of 5-month-old Grx2 KO mice.The 8-OHdG content and ROS fluorescence intensity in the lens of 5-month-old Grx2 KO mice were (3.886±0.326)ng/ml and 1 594±132, which were significantly higher than (3.531±0.250)ng/ml and 1 157±123 in WT mice ( t=2.711, P=0.033; t=3.384, P=0.028).The relative expression levels of Grx2, GSH and Bcl-2 in the lens of 5-month-old Grx2 KO mice were 0.23±0.01, 0.70±0.06 and 0.32±0.03, which were significantly lower than 0.52±0.02, 1.04±0.08 and 0.49±0.04 of WT mice ( t=2.815, P=0.020; t=2.457, P=0.033; t=2.279, P=0.041). Conclusions:Grx2 KO and Grx2 KI mouse models are successfully established in this study.The occurrence and development of age-related cataract are accelerated in Grx2 KO mice.