Study On The Expression Of Opticin In The Eye Of Diabetic Mice

Purpose:It is known that contraction of vitreous could induce the development or exacerbation of diabetic macular edema.Recent studies have shown that a novel member of extracellular matrix leucine rich repeat proteins called opticin has a function in maintaining vitreous stability and structure,its ability to bind chondroitin 4-sulfate of typeⅨcollagen and versican may allow vitreous to form a contiguous and stable collagen network.To determine whether a variety of opticin expression in diabetic vitreous in vivo to characterize further its role in the induction of diabetic vitreous alteration,real time PCR and western blot experiments were performed in this study to determine the discrepancy of opticin expression in Non-Obese Diabetic mice(NOD mice) with and without diabetes.Methods:NOD mice with a blood glucose level of 16.7mmol/L or higher at least twice by FPG test were included in diabetic group(n=10),while the same amounts of NOD mice without diabetes were used as non-diabetic controls.All the eyes of each animal were enucleated.After immediately frozen treatment,the eyeballs were sliced around the limbus area using microscopic operation,then the vitreous,retina and sclera was carefully separated.Opticin and the Optc gene mRNA levels in these tissues were measured by Western blot and real time PCR analysis respectively.Student's t-test was used to study differences between two groups.Statistical analyses were performed using SPSS version 11.0 software.Results:Western blot analysis specifically identified opticin as a prominent 55-72 kDa component,band of approximately 60 kDa was showed in all vitreous,retina and sclera but with decreasing contents(vitreous＞retina＞sclera).Opticin levels of vitreous and retina in diabetic group,were significantly lower than that of controls(vitreous; t=4.42,p＜0.01,retina;t=4.58,p＜0.01),on the other hand,opticin level did not change significantly in sclera(t=0.27,p＞0.05).Further real time PCR experiments demonstrated that mRNA of OPTC was present in vitreous,retina and sclera.Compared to the non-diabetic group,the decreases of OPTC mRNA in vitreous and retina in diabetic mouse were significant(vitreous;t=3.297,p＜0.05,retina;t=2.484,p＜0.05),but was still no significant in sclera in diabetic mice(t=0.269,p＞0.05).Conclusion:Based on our experiments,opticin was found to be expressed in vitreous,retina,and sclera,predominantly distributed in vitreous.Our results demonstrated the decreases of opticin both in vitreous and retina in diabetic mice suggesting that opticin expression may involve in the underlying pathologic alteration of diabetic vitreous.