Establishment and identification of cardiomyocyte arhGEF18 gene conditional knockout mice

Left ventricular noncompaction (LVNC) is a heterogeneous disorder with unclear genetic causes. The arhGEF18 gene is a guanine nucleotide exchange factor related to the Rho pathway and a possible predisposing gene for LVNC. In this study, a mouse model of arhGEF18 gene conditional knockout (cKO) in cardiomyocytes was established using the Cre-LoxP system to provide an animal model for the genetic study of LVNC. ArhGEF18 cKO mice were obtained by crossing arhGEF18^f/+/myh6-Cre⁺ and arhGEF18^f/f mice. The mRNA and protein expression levels of arhGEF18 in different tissues were verified. The myocardial cytoskeleton and polar protein expression, the survival rate, cardiac function, and cardiac histology of model mice were determined. ArhGEF18 cKO mice were successfully established. ArhGEF18 was confirmed to be specifically knocked out in the myocardial tissue of arhGEF18^f/f/myh6-Cre⁺ mice at the mRNA and protein levels, and the knockout rate was approximately 75%. The relative expression levels of cytoskeleton and cell polarity proteins such as α/β-tubulin, Scribble, Crb2, and PAR3 in the cKO group were significantly lower than those in the control group (p < 0.05). During monitoring, the survival rate, cardiac systolic function, and myocardial structure of arhGEF18^f/f/myh6-Cre⁺ mice were not significantly different from those of control mice. A mouse model of cardiomyocyte arhGEF18 gene cKO was successfully established, and it was confirmed that knocking out arhGEF18 changed cytoskeleton and cell polar protein expression levels in the myocardium. However, there was no obvious LVNC phenotype in the constructed arhGEF18 cKO mice.