Correlation Between Foxa2 Gene And The Formation Of Atrial Septal Defect In NIPBL Deficient Mice

Background:Delong heat Syndrome?Cornelia DE Lange Syndrome,CdLS?is a kind of expression which is system developmental disorders of genetic disease,according to the related research at present think with disease and autosomal dominant and main X-ray chain two genetic ways,often show the growth and development obstacle,arm and hand malformations,mental retardation and abnormal behavior of the interval and heart defects.The incidence of the disease in the general population is 1 in 10,000,and its occurrence has a serious impact on the quality of life of patients and the financial burden of their families.CdLS has a high mortality rate,and the cause of death is related to congenital organ development abnormalities,especially congenital heart disease,among which ventricular septal and atrial septal defects are the most common^[1].In 2004,Tonkin et al.found that Nipped-B similar gene?Nipped-B-like,NIPBL?mutation can lead to autosomal dominant inheritance of CdLS^[2].Kawauch et al.reported that NIPBL^+/-transgenic mice carrying haploid NIPBL gene.Approximately 75 to 80%of NIPBL^+/-mice died within 4 weeks of birth,and by prenatal?E17.5--E18.5?41%of all offspring had mutations in their genotypes,suggesting a nearly normal 50%Mendelian distribution.In E17.5--E18.5,nearly half of NIPBL^+/-embryos were found to have a large atrial septal defect,and abnormalities of ventricle and ventricular muscle were also found.Studies have shown that the most direct effect of the decrease of NIPBL gene level is that the decrease of SOX17 or Foxa2expression level leads to intestinal defects.More importantly,when the SOX17 and Foxa2expression levels are reduced at the same time,nearly 60%of embryos show severe intestinal defects and the embryo rate of intestinal defects increases sharply^[3].SOX17 and Foxa2 these genes in heart,and play an important role in the development of the internal organs,the main function of these genes is to regulate the endoderm development^[4]heart and gut development comes from the common endoderm,and the development of the heart changes more complex than blind development,SOX17 and Foxa2 during the differentiation of the endoderm has a certain degree of change.At the same time,Foxa2 expression level in the axial direction?nodal and notochord?of the endoderm and mesoderm was significantly higher than that of other endoderm marker genes^[5],and the expression range involved epitaxy,myocardium,endocardium,anterior heart,outflow tract and cardiac cushion^[6].Therefore,we hypothesized that the formation of atrial septal defect in the NIPBL^+/-mouse model may be related to the down-regulation of Foxa2 gene expression.Objective:In this study,the growth and development of mice were evaluated by measuring the body weight,and the expression of the transcription factor Forkhead box A2?Foxa2?gene in the heart tissue was also discussed,so as to investigate the relationship between the formation of atrial septal defect and Foxa2 gene expression in the NIPBL^+/-mouse model.It provides a new idea for the diagnosis and intervention of CdLS and congenital heart disease.Methods:NIPBL^+/-mice were used as the experimental group,and wild-type NIPBL^+/+mice were used as the control group.Pathological sections and HE staining were made from mouse heart tissue to observe the effect of NIPBL gene defect on the development and changes of mouse heart,as well as the structural characteristics of atrial septal defect.Residual cardiac tissue using reverse transcription PCR?reverse transcription PCR,rt-pcr?method to detect Foxa2 in the experimental group and control group in the heart tissue mRNA level,using Western imprinting method to detect the cell samples Foxa2 gene protein expression level.Results:Abnormal defect was found in the atrial septum of NIPBL defect mice.The weight of mice in the experimental group was lower than that of the control group,P<0.05.At the same time,Foxa2 gene expression and protein expression were decreased in the samples without atrial septal defect in the experimental group,P<0.05,and the difference was statistically significant.Conclusion:Foxa2 gene expression was decreased in NIPBL^+/-deficient mice,which resulted in growth retardation and weight loss to some extent.The abnormal cardiac septal defect in nipbl-deficient mice might be related to the decreased expression of Foxa2 gene in myocardial cells caused by the defective NIPBL gene in mice.