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.
ABSTRACT
Objective To investigate the variation of the thioredoxin system (Trx),and the role of it in transient out-ward potassium current (Ito) channels in left ventricular myocytes of diabetes mellitus (DM) in rats. Methods Forty-five SD rats were divided into DM group and control group. DM group were treated with streptozotocin (STZ) to induce DM model. The values of left ventricular end diastolic diameter (LVEDD), end-systolic diameter (LVESD), fractional shortening (LVFS), ejection fraction (LVEF) and heart rate (HR), QRS duration and corrected QT (QTc) interval were detected by echocardiogra-phy (UCG) and electrocardiogram (ECG) in two groups. The left ventricular myocardial tissue samples were taken to detect the Trx,glutaredoxin (GRX),thioredoxin reductase (TrxR) and glutathione reductase (GR) by using UV spectrophotometer. The level of free thiol (P-SH) of total cardiac protein was detected by 5, 5′-dithio-bis-2-nitrobenzoic acid method. Ito of the cardiomyocytes was recorded by whole-cell patch-clamp method. After being incubated in vitro with insulin(Ins), treated with TrxR inhibitor-auranofin(AF) and 13-cis-retinoic acid(RA), the changes of Ito of the cardiomyocytes were observed. Results Compared with control group, the values of heart rate (HR), left ventricular minor axis decurtaion rate (LVFS), left ventricular ejection fraction (LVEF) and TrxR were lower in DM group. The values of LVEDD, LVESD, QRS and QTc inter-vals, Trx, Grx and P-SH were higher in DM group than those of control group. Ito density was significantly higher in DM+Ins group than that of DM group, Ins+RA group and Ins+AF group when the stimulation voltage ≥ 0 mV (P ＜ 0.05). Conclusion The impaired Trx system in diabetic rat myocardium was the electrophysiological basis of the reduced ventric-ular function and arrhythmia. And Ins was able to reverse the decreased Ito of cardiomyocytes in DM rats.
ABSTRACT
To cope with oxidative stress, Candida albicans possesses several enzymes involved in a number of biological processes, including superoxide dismutases (Sods) and glutaredoxins (Grxs). The resistance of C. albicans to reactive oxygen species is thought to act as a virulence factor. Genes such as SOD1 and GRX2, which encode for a Sod and Grx, respectively, in C. albicans are widely recognised to be important for pathogenesis. We generated a double mutant, Δgrx2/sod1, for both genes. This strain is very defective in hyphae formation and is susceptible to killing by neutrophils. When exposed to two compounds that generate reactive oxygen species, the double null mutant was susceptible to menadione and resistant to diamide. The reintegration of the SOD1 gene in the null mutant led to recovery in resistance to menadione, whereas reintegration of the GRX2 gene made the null mutant sensitive to diamide. Despite having two different roles in the responses to oxidative stress generated by chemical compounds, GRX2 and SOD1 are important for C. albicans pathogenesis because the double mutant Δgrx2/sod1 was very susceptible to neutrophil killing and was defective in hyphae formation in addition to having a lower virulence in an animal model of systemic infection.