Heart and neural tube defects in transgenic mice overexpressing the Cx43 gap junction gene

Abstract

Transgenic mice were generated containing a cytomegaloviral promoter driven construct (CMV43) expressing the gap junction polylpeptide connexin 43. RNA and protein analysis confirmed that the transgene was being expressed. In situ hybridization analysis of embryo sections revealed that transgene expression was targeted to the dorsal neural tube and in subpopulations of neural crest cells. This expression pattern was identical to that seen in transgenic mice harboring other constructs driven by the cytomegaloviral promoter (Kothary, R., Barton, S. C., Franz, T., Norris, M. L., Hettle, S. and Surani, M. A. H. (1991) Mech. Develop. 35, 25–31; Koedood, M., Fitchel, A., Meier, P. and Mitchell, P. (1995) J. Virol. 69, 2194–2207), and corresponded to a subset of the endogenous Cx43 expression domains. Significantly, dye injection studies showed that transgene expression resulted in an increase in gap junctional communication. Though viable and fertile, these transgenic mice exhibited reduced postnatal viability. Examination of embryos at various stages of development revealed developmental perturbations consisting of cranial neural tube defects (NTD) and heart malformations. Interestingly, breeding of the CMV43 transgene into the Cx43 knockout mice extended postnatal viability of mice homozygote for the Cx43 knockout allele, indicating that the CMV43 trangsene may partially complement the Cx43 deletion. Both the Cx43 knockout and the CMV43 transgenic mice exhibit heart defects associated with malformations in the conotruncus, a region of the heart in which neural crest derivatives are known to have important roles during development. Together with our results indicating neural-crest-specific expression of the transgene in our CMV-based constructs, these observations strongly suggest a role for Cx43-mediated gap junctional communication in neural crest development. Furthermore, these observations indicate that the precise level of Cx43 function may be of critical importance in downstream events involving these migratory cell populations. As such, the CMV43 mouse may represent a powerful new model system for examining the role of extracardiac cell populations in cardiac morphogenesis and other developmental processes.

Generation and Characterization of an Inducible Cx43 Overexpression System in Mouse Embryonic Stem Cells

“…We have opted for an inducible genetic system because CMV-driven ubiquitous Cx43 overexpression in mice was reported to cause morbidity and postnatal mortality due to neural tube and conotruncal heart defects [ 29 ], a phenotype which was reminiscent of Cx43 KO models [ 21 , 47 ]. We tested our genetic construct in ES cells, as well as HeLa cells and 3T3-fibroblasts, and observed no leakiness in the absence of Cre, whereas AAV-Cre-mediated excision of the floxed stop cassettes resulted in Cx43 overexpression in cells with and without endogenous Cx43 expression.…”

“…To address these aspects, we have taken a different approach from KOs by generating an inducible Cx43 overexpression model in pluripotent mouse embryonic stem (ES) cells. This strategy was chosen, since earlier experiments in mice illustrated that ubiquitous overexpression of Cx43 resulted in embryonic and postnatal morbidity and reduced postnatal viability [ 29 ]. We reasoned that Cx43 overexpression could also have (adverse) effects on the propagation, development, and differentiation of native cells and/or ES cell-derived cell populations in vitro.…”

The atlas of ACE2 expression in fetal and adult human hearts reveals the potential mechanism of heart-injured patients infected with SARS-CoV-2

“…In our study, the GJA5 was downregulated in CM-A in CAD HF, and Vozzi et al ( 57 ) found that the connexin40 was expressed higher in atrium than that in ventricle in human heart. However, the expression level of GJA1 was enhanced in DCM HF, and some studies had reported that both decrease and increase of GJA1 could cause abnormal heart function ( 58 , 59 ). Previous study also showed that the downregulation expressions of connexin40 and connexin43, which disturbed the Wnt signaling and caused the calcium signal dysregulation ( 36 , 37 , 60 ).…”

History of the study of the neural crest (review)

“…Нокаут гиалуронансинтазы-2 (Has2), одного из членов семейства трех генов, участвующих в синтезе гиалуронана у млекопитающих, нарушает развитие эндокардиальной подушки сердца (производное клеток нервного гребня) (tuber endocardiale atrioventriculare, LNE), сформированный дефект связан с ингибированием миграции клеток сердечного нервного гребня (CarNCCs) [128][129][130][131][132].…”