GATA4 Protects From Hyperglycemia Induced Endothelial Dysfunction Via Regulating NOX4 Transcription

Background:Diabetes is a chronic disease,caused by a lack of the insulin secretion or insulin utilization deficiency.It is an important public health problem in the 21st century.According to data from the world health organization and the global alliance for diabetes,there are 422 million adults in the world suffer from diabetes in 2014,that means one in eleven adults suffers from diabetes,and another 318 million adults are under impaired glucose tolerance.Impaired glucose tolerance is high risk factor of diabetes in the future.The increasing of the number of diabetes patients is much more than we expected.The WHO estimates that to 2040,the number of diabetic patients will be 642 million,it equals to one in ten adults is diabetes.The mortality and morbidity of Diabetes are very high.According to statistics,diabetes and cardiovascular disease,cancer,chronic respiratory diseases together to become the world’s four major cause of death.Compared with people without diabetes,patients with diabetes are at higher risk of suffering the disabling or fatal diseases.Diabetes is often accompanied by the occurrence of cardiovascular diseases,about 41%of the patients with type 2 diabetes complicated with cardiovascular diseases.Compared with people without diabetes,the probability of coronary heart disease and stroke in Type 2 diabetes patients increases to 2～4 times.75%～80%of diabetes patients died of myocardial infarction.As a result,we think "diabetes is equal to cardiovascular diseases".Endothelial dysfunction is the main pathogenesis of cardiovascular diseases in diabetes.Hyperglycemia impaired endothelial dependent diastolic function,means NOX family produces a large number of ROS in endothelial cells.On the one hand,NO reacts with super oxygen ions generating NO3-,which reduce the biological activity of NO.On the other hand NO3-uncoupling eNOS,eNOS no longer generate NO,O2-production instead,mediate the occurrence and development of cardiovascular disease.However in recent years,some studies find that NOX4 has a protective effect on endothelial dysfunction.However,the mechanism remained unclear.So a more comprehensive understanding of NOX4 signaling was essential and will be useful for endothelial dysfunction treatment.Aim:Recent studies indicated that NOX4 which was reported to produce H2O2 had a protective role on endothelial dysfunction by activating AKT1/peNOS pathway.However,the mechanism remained unclear.Here we investigated the upstream signaling and mechanism involved in NOX4 regulation.Methods:1.The promoter-binding transcription factors profiling plate array was performed to detect GATA family has a transcriptional role on NOX4.Since this assay cannot differentiate the subtype of GATA family,then we use GATA1-6 overexpression plasmid and chromatin immunoprecipitation assay to confirm GATA4 is the transcription factor for NOX4.2.In this study,mice received an intraperitoneal injection of STZ to make a diabetes model.As the result in Immunohistochemistry,mice with diabetes had a lower expression of GATA4 in the endothelium of thoracic aorta.3.HUVEC was exposed to 33 mM glucose for 72h.Compare with the control group,as shown in WB and Q-PCR,hyperglycemia induced a decrease in GATA4 expressions in hyperglycemia HUVECs in both mRNA and protein levels.4.We make the transfection of GATA4 overexpression plasmid to make GATA4 overexpression,then measure the NO as well as the NOX4、p-eNOS level in hyperglycemia stimulated endothelial cellsResults:1.The promoter-binding transcription factors profiling plate array was performed to detect GATA family has a transcriptional role on NOX4.Since this assay cannot differentiate the subtype of GATA family,we measured NOX4 mRNA level using GATA1-6 overexpression plasmid.As shown in our result,GATA4 induced a largest increase in NOX4 mRNA level.Thus we assumed that GATA4 was the transcription factor for NOX4 then we use Chromatin immunoprecipitation assay to confirm GATA4 is the transcription factor for NOX4.2.GATA4 is downregulated in hyperglycemia HUVECs and diabetes mice.3.Compared with the control group,GATA4 overexpression increased the NO as well as the NOX4 level and p-eNOS level in hyperglycemia stimulated endothelial cells.GATA4 improved endothelial function in diabetes.Conclusion:NOX4 improved endothelial function in diabetes.GATA4 is the transcription factor for NOX4,it starts the expression of NOX4,by raising peNOS and increasing the release of NO,protecting the endothelial dysfunction in diabetes.