HIF-1α Promotes Transcription Of TAK1 In Cardiac Hypertrophy Induced By AngⅡ

Objective:Hypertensive myocardial hypertrophy is a disease caused by pressure load and angiotensin II(Angiotensin II,Ang Ⅱ).It increases the probability of cardiovascular occurrence by 2-4 times.If it is not intervened and treated in time,heart failure,myocardial infarction and other heart diseases will occur if it is not allowed to develop,which is a serious threat to human health.Hypoxia-inducible factor 1α(HIF-1α)was increased and stable under the condition of hypoxia.HIF-1αenters into the nucleus and forms a stable dimer with HIF-1β to promote the transcription of the related genes.It is reported that HIF-1α can regulate oxygen transport under hypoxia by regulating angiogenesis and remodeling.Knockout of HIF-1α showed decreased capillaries and abnormal myocardial metabolism in rats.Moreover,the expression of HIF-1α is increased in the heart of patients with ischmic cardiomyopathy.In addition to hypoxia-induced expression of HIF-1α,AngⅡ can also induce the increase in HIF-1α in vascular tissue.Transformation growth factorβ-activated kinase 1(TAK1)also increases under the treatment of AngⅡ.As an important regulator of cardiac hypertrophy,TAK1 plays an important role in the occurrence and development of cardiac hypertrophy.TAK1 gene mutation in rats will show vasodilation,deficiency in vascular smooth muscle and other phenomena.Under AngⅡ stimulation or pressure overload,the expression of TAK1 is increased.Activated TAK1 cascade causes downstream signal pathways to promote the expression of hypertrophy-related factors.Although it has been reported that HIF-1αand TAK1 play an important role in the occurrence of pathological myocardial hypertrophy,respectively,the correlation between them is not clear.Therefore,we explored the relationship between HIF-1α and TAK1 in pathological cardiac hypertrophy.Materials and methods:In vivo experiment: the myocardial tissue of patients with myocardial hypertrophy was collected,the rat model of cardiac hypertrophy was established,and the cardiac tissue sections were prepared.Hematoxylin-eosin Staining(HE)was used to determine whether cardiac hypertrophy occurred,and immunohistochemistry was used to determine the expression of HIF-1α and TAK1 during cardiac hypertrophy.In vitro experiment: human AC16 cells were transfected with sh HIF-1α plasmid lentivirus and overexpressed HIF-1α plasmid lentivirus,respectively,and the stable cell lines were screened.The luciferase reporter gene plasmids inserted with different TAK1 promoters were cotransfected into different cells and stimulated with AngⅡ for 0 or 24 hours,and the samples were collected.The protein levels of ANP,HIF-1α and TAK1 were detected by western blot,and the binding of HIF-1α to TAK1 promoter was detected by Dual-luciferase reporter assay and Chromatin Immunoprecipitation assay.Results:In vivo,cardiomyocyte hypertrophy occurred in the myocardium of patients with cardiac hypertrophy and AngⅡ-induced cardiomyocyte hypertrophy in rats,and the expression of HIF-1α and TAK1 increased at the same time.In vitro,when AC16 cells were stimulated with different concentrations of AngⅡ(0μM,0.1μM,1μM),the expressions of HIF-1α and TAK1 increased with the increase of AngⅡ concentration.When sh HIF-1α cells were stimulated with different concentrations of AngⅡ(0μM,1μM)for 24 hours,the expression of HIF-1α was inhibited and the expression of ANP and TAK1 protein was also decreased.Different TAK1 promoter sequences and mutant sequences were inserted into luciferase reporter gene plasmid and co-transfected into AC16 cells,and stimulated with AngⅡ for 0 or 24 hours.The results showed that the protein expression of HIF-1α in cells stimulated by AngⅡ for 24 hours was increased,and the activity of TAK1 promoter was enhanced when AC16 was inserted into all sequences of TAK1 promoter,-2000~-1000 bp and-1285~-1274 bp.When-2000~-1000 bp and-1285~-1274 bp sequences were inserted into luciferase reporter gene plasmid and co-transfected into sh RNA-HIF-1α cells,the expression of HIF-1α decreased and the activity of TAK1 promoter decreased.When-2000~-1000 bp and-1285~-1274 bp sequences were inserted into luciferase reporter gene plasmid and co-transfected into p CDNA-HIF-1α cells,the expression of HIF-1αwas increased,and the activity of TAK1 promoter was enhanced.In AC16 cells,after being stimulated by AngⅡ for 24 hours,there was a large amount of HIF-1α binding to promoter of TAK1.In p CDNA-HIF-1α cells,the binding amount of HIF-1α to TAK1 DNA sequence increased.Conclusion:(1)In the heart of patients with cardiac hypertrophy,the expressions of HIF-1α and TAK1 protein increase at the same time.(2)Cell hypertrophy occurred in rat cardiomyocytes and AC16 cells induced by AngⅡ,and the expressions of HIF-1α and TAK1 protein increase at the same time.(3)As a transcription factor of TAK1,HIF-1α binds to the TAK1 promoter-1285~-1274 bp sequence to promote the expression of TAK1 and promotes the occurrence of cardiac hypertrophy.