Effect And Mechanism Of ? 1,3 Galactosyltransferase 2 Gene Knockout Induce Cardiac Injury In Mice

Objective? 1,3-galactosyltransferase 2(B3GALT2)is a glycosyltransferase,which can change the configuration of metabolic substrates and affect metabolism.It is also a membrane surface protein located in ribosome and Golgi body.It can modify many proteins and participate in many biological processes,such as inflammation.Both metabolic abnormalities and inflammation can damage the heart.Therefore,this study used B3GALT2 gene knockout mice as a model to observe the changes of heart function and structure,and further explore its mechanism of action from the aspects of inflammation and apoptosis.MethodsSix-month-old SPF-grade B3GALT2 knockout mice were divided into wild type(WT),heterozygous(HET)and homozygosity(HOM)according to genotype test results.Wild type was the blank group.The left ventricular systolic fraction(LVFS)and left ventricular ejection fraction(LVEF)were compared by echocardiography in small animals to observe the changes of heart function.Body weight(BW),heart weight(HW)and left ventricular weight(LVW)were measured.The heart size was compared by calculating the whole heart index and left ventricular index;HE staining was used to observe the changes of cardiac structure;Western blot was used to detect the expression of ANP and BNP protein and observe the changes of hypertrophy index.Western blot was used to detect the expression of TLR4,NF-?B and pNF-?B.The expression of inflammatory signaling pathway-related proteins was observed.The expression of NF-?B was detected by immunohistochemistry.TUNEL staining was used to observe the nuclear staining and calculate the apoptotic rate.Western blot was used to detect the expression of Bcl-2,Bax and caspase-3 protein,and to clarify the effect of B3GALT2 on apoptosis.ResultsBlood pressure results showed that systolic blood pressure(SBP)and diastolic blood pressure(DBP)were decreased in HET and HOM groups,suggesting that B3GALT2 could affect the physiological function of mice.LVFS and LVEF results showed that HET group was significantly lower than WT group and HOM group,and HOM group was lower than WT group,suggesting that gene knockdown can reduce cardiac function.Comparing the heart size,we found that the heart of HET and HOM group was significantly larger than that of WT group.Further comparing the heart index and left ventricular index,we found that the heart index and left ventricular index of HET group and HOM group were significantly higher than that of WT group,and that of HET group was slightly higher than that of HOM group.HE staining showed that the volume of myocardial cells of HET group and HOM group was significantly larger than that of WT group,and that of HOM group was slightly smaller than that of HET group.Compared with WT group,the expression of ANP and BNP in HET group and HOM group increased significantly,but the expression of ANP and BNP in HOM group was lower than that in HET group.These results suggest that B3GALT2 knockout can lead to an increase in cardiac volume and weight,and an increase in cardiomyocyte volume.Compared with the WT group,the TLR4,NF-?B,pNF-?B protein in HET group and HOM group were highly expressed,and the expression of NF-?B in HET group was higher than that in HOM group.Immunohistochemical results showed that the expression of NF-?B in WT group was almost absent in the nucleus,and the expression of NF-?B in HET group was high in the nucleus and significantly increased in the whole.The expression of NF-?B in HOM group increased both in the nucleus and cytoplasm.These results suggest that B3GALT2 knockout can activate TLR4/ NF-?B signal and promote inflammation.The number of nuclei stained by TUNEL in HET group was significantly higher than that in other two groups,and that in HOM group was significantly higher than that in WT group.After calculating the apoptotic rate,it was found that the apoptotic rate in HET group was higher than that in HOM group and WT group,and that in HOM group was higher than that in WT group.Bax and caspase-3 were highly expressed in HET and HOM groups,while Bcl-2 was low.Bax and caspase-3 in HET group were higher than that in HOM group,and Bcl-2 was lower than that in HOM group.These results indicated that B3GALT2 knockout could increase the apoptotic rate of myocardial tissue.Conclusions1.B3GALT2 gene knockout can reduce cardiac function,alter myocardial structure and cause hypertrophy.2.B3GALT2 gene knockout can induce inflammation by activating TLR4/NF-?B signaling pathway.3.B3GALT2 gene knockout can promote apoptosis by activating the internal pathway of apoptosis.