A Mouse Model of Human Congenital Heart Disease

Abstract

Background Heterozygous human mutations of NKX2-5 are highly penetrant and associated with varied congenital heart defects. The heterozygous knockout of murine Nkx2-5, in contrast, manifests less profound cardiac malformations, with low disease penetrance. We sought to study this apparent discrepancy between human and mouse genetics. Since missense mutations in the NKX2-5 homeodomain (DNA binding domain) are the most frequently reported type of human mutation, we replicated this genetic defect in a murine knock-in model. Methods and Results We generated a murine model in a 129/Sv genetic background by knocking-in an Nkx2-5 homeodomain missense mutation previously identified in humans. The mutation was located at homeodomain position 52Arg→Gly (R52G). All the heterozygous neonatal Nkx2-5+/R52G mice demonstrated a prominent trabecular layer in the ventricular wall, so called noncompaction, along with diverse cardiac anomalies, including atrioventricular septal defects, Ebstein’s malformation of the tricuspid valve, and perimembranous and/or muscular ventricular septal defects. In addition, P10 Nkx2-5+/R52G mice demonstrated atrial septal anomalies, with significant increase in the size of the inter-atrial communication and fossa ovalis, and decrease in the length of the flap valve compared to control Nkx2-5+/+ or Nkx2-5+/− mice. Conclusion The results of our study demonstrate that heterozygous missense mutation in the murine Nkx2-5 homeodomain (R52G) are highly penetrant, and result in pleiotropic cardiac effects. Thus, in contrast to heterozygous Nkx2-5 knockout mice, the effects of the heterozygous knock-in mimic findings in humans with heterozygous missense mutation in NKX2-5 homeodomain.

Mouse Model of Human Congenital Heart Disease

“…In addition, ventricular noncompaction (100%), ventricular septal defects (82%), atrioventricular septal defects (18%) and tricuspid valvar anomalies (47%) were displayed in the knock-in mice. These lesions were not demonstrated in wild-type mice, but some of them were found with lower incidences in heterozygous knock-out mice 8 .…”

“…In order to understand the potential disease mechanisms underlying heterozygous NKX2-5 mutation, we recently generated and analyzed a heterozygous knock-in mouse model by introducing a disease-causing missense mutation in homeodomain position 52, and Nkx2-5 protein position 188 in Nkx2-5 proteins, Arg52(188)Gly, Nkx2-5 +/R52G 8 . In contrast to heterozygous knock-out mice ( Nkx2-5 +/− ), we found that the cardiac effects of knock-in mice ( Nkx2-5 +/R52G ), hereafter described as Nkx2-5-KI mice, were similar to those observed in humans.…”

Single-Cell Resolution of Temporal Gene Expression during Heart Development

“…Nkx2.5 +/− mice recapitulate many of these cardiac phenotypes albeit with incomplete penetrance (Ashraf et al, 2014; Biben et al, 2000; Bruneau et al, 2001). We hypothesized that haploinsufficiency of transcription factors Nkx2.5 cause heart malformations by altering developmental transcription in specific cardiac lineages.…”

“…We identified transcripts that delineated atrial and ventricular CMs, and ECs and fibroblast-enriched cell lineages. We also characterized CMs derived from stem cells and CMs and ECs derived from a congenital heart disease mouse model with haploinsufficiency of Nkx2.5 , a critical transcription factor that is expressed early in cardiogenesis (Ashraf et al, 2014; Biben et al, 2000; Bruneau et al, 2001). …”

Formation and Malformation of Cardiac Trabeculae: Biological Basis, Clinical Significance, and Special Yield of Magnetic Resonance Imaging in Assessment

“…13 Excessive trabeculation discovered at the time of cardiac imaging may therefore represent one of three things: a benign phenotype not uncommon in the general population, 13 a distinguishing feature of isolated LVNC, or a shared morphological trait 10,14,15 common to many cardiac diseases clinically and clustering into distinct phenotypes. Phenotyping in small animal models of LVNC has already shown how excessive trabeculation is commonly associated with either dilated cardiomyopathy 16 (DCM) or congenital heart disease (CHD) [17][18][19] and the same is also true in adult and paediatric cardiology given that 8 of the 12 LVNC phenotypes reported in the Online Mendelian Inheritance in Man database 20 (OMIM) have similar associations ( Table 2). Human genetic studies have shown how, like many other heart muscle disorders, LVNC exhibits significant genetic heterogeneity 10 (e.g.…”