RESUMO
BACKGROUND:The second heart field is crucial for the development of the embryonic heart.Abnormal development of the second heart field can result in multiple cardiac malformations.After Cx43 gene knockout,reduced formation and proliferation of cells of the second heart field can be observed,but the specific reason remains unclear. OBJECTIVE:(1)To determine whether β-catenin,Smo and Cx43 were co-expressed in the second heart field and the endoderm,we observed the expression patterns of these proteins.(2)To explore whether Cx43 interacts with the Wnt/β-catenin pathway or the Shh pathway in the development of the second heart field. METHODS:Serial paraffin sections of the mouse embryos at embryonic days 10-12 were selected for immunohistochemical staining,hematoxylin-eosin staining and immunofluorescence staining.The primitive gut of mouse embryos at embryonic day 11 was separated for western blot assay and co-immunoprecipitation. RESULTS AND CONCLUSION:(1)Cx43 and Isl1 were co-expressed in some mesenchymal cells on the ventral side of the foregut and dorsal wall of the pericardial cavity of mouse embryos at embryonic days 10-12;Isl1 positive cells increased while Cx43 positive cells increased.(2)Cx43 and β-catenin were co-expressed in the ventral part of the endoderm at embryonic days 10-12.(3)Cx43 and Smo were co-expressed in the endoderm at embryonic days 10-12.(4)The co-immunoprecipitation results confirmed that there was an interaction between Cx43 and β-catenin,which suggested that Cx43 interacted with β-catenin to participate in the development of the second heart field.
RESUMO
Hypoplastic right heart syndrome(HRHS) is characterized by hypoplastic right ventricle (RV); Numerous transcriptional cascades in the second heart field (SHF) regulateRVdevelopment. The relationship of SHF gene variants with humanHRHS remains unknown. The whole lengths of 17 SHF genes were sequenced in 16 HRHS, and the selected single-nucleotide variants (SNVs) were then genotyped in HRHS, other congenital heart disease (CHD) and healthy control. Luciferase assay was performed to verify the effect of FOXC2: rs34221221A>GandTBX20: rs59854940C>Gat the transcription level. There were 151 (12.86%) novel SNVs after sequence analysis, of which three were in exons (one was synonymous SNV and two were nonsynonymous SNVs), two in promoter, and most SNVs (89.95%) were in intronic regions. Genotype analyses revealed that the minor alleles of FOXC2: rs34221221 A>G and TBX20: rs59854940 C>G could increase HRHS risk (P<0.05), but not in other CHD or healthy control. Luciferase assay showed that the minor G allele in rs34221221 significantly increased FOXC2 transcription while in rs59854940 it decreased TBX20 transcription significantly. Novel variants of SHF gene associated with HRHS were identified. Minor alleles in two variants from FOXC2 and TBX20 could increase the risk of HRHS.