GnT-V modulates myocardial injury in diabetic mice by affecting autophagy
Objective To investigate the effect of N-acetylglucosaminetransferase-V on myocardial injury in diabetic cardiomyopathy(DCM)mice and its potential molecular mechanism.Methods Thirty 6-8-week-old male C57BL/6 mice were randomly divided into control group(Con group),DCM group,and DCM+adeno-associated virus carrying GnT-V-specific small hairpin RNA(DCM+AAV-shGnT-V group),with 10 mice in each group.The mice in DCM group were injected intraperitoneally with 50 mg/kg streptozotocin for 5 d to induce a diabetes model(randomized blood glucose ≥16.7 mmol/L),and then continued to be fed with universal diet for 12 weeks to induce a diabetic cardiomyopathy model.The mice in Con group were intraperitoneally injected with the corresponding dose of citrate buffer.The mice in DCM+AAV-shGnT-V group were given 40 μL of AAV-shGnT-V with a titer of 1 × 1010 PFU/mL by myo-cardial injection 4 weeks after the successful induction in diabetes model to knock down the GnT-V gene.Echocardiography was used to detect the cardiac function,Masson staining was used to observe the myocardial fibrosis,TUNEL staining was used to detect the apoptosis,immunohistochemical staining was used to observe the expressions of GnT-V and Beclin1 in myocardial tissues,and Western blot was used to detect the expressions of autophagy-related proteins LC3,P62,and PI3K/AKT pathway-related proteins.Results Compared to Con group,the cardiac contractile function was significantly reduced in DCM group(P＜0.05),the fibrosis of myocardial tissue was significantly increased(P＜0.05),the apoptosis rate of cardiomyocytes was significantly increased(P＜0.05),the expres-sions of GnT-V,Beclin1,and LC3 Ⅱ/LC3 Ⅰ were significantly increased in myocardial tissue,the expression of P62 was significantly reduced(P＜0.05),and PI3K and AKT phosphorylation levels were significantly reduced(P＜0.05).Compared to DCM group,the cardiac contractile function was significantly improved in DCM+AAV-shGnT-V group(P＜0.05),the myocardial tissue fibrosis was significantly decreased(P＜0.05),the apoptosis rate of cardiomyocytes was significantly reduced(P＜0.05),the expressions of GnT-V,Beclin1 and LC3 Ⅱ/LC3 Ⅰ were significantly downregulated,the expression of P62 was significantly increased(P＜0.05),and PI3K and AKT phosphorylation levels were significantly enhanced(P＜0.05).Conclusion GnT-V knockdown can improve the progression of myocardial tissue fibrosis and reduce the cardiomyocyte apoptosis in diabetic cardiomyopathy mice.This effect may be related to the activation of the PI3K/AKT signaling pathway,thus inhibiting the myocardial autophagy.
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