GSE201018
I536T variant of RBM20 affects splicing of cardiac structural proteins that are causative for developing dilated cardiomyopathy
Background: RBM20 gene is one of the genetic predispositions for dilated cardiomyopathy (DCM). Variants in RS domain has been reported in many DCM patients, while the pathogenicity of variants within the RNA-recognition motif remains unknown.  Methods and results: We detected two human patients of I536T-RBM20 variant without DCM phenotype in sudden death cohorts. We performed splicing reporter assay and generated I538T knock-in (KI) mouse model (Rbm20I538T) in order to reveal the significance of this variant. The reporter assay revealed that human I536T variant affected TTN splicing pattern compared to wild-type. In the mouse experiments, Rbm20I538T mice presented a different splicing pattern in Ttn, Ldb3, Camk2d and Ryr2. The expression of Casq1, Mybpc2 and Myot were upregulated in Rbm20I538T mice. Whereas, Rbm20I538T mice did show neither DCM nor cardiac dysfunction by histopathological examination and ultrasound echocardiography.  Conclusion: I536T-RBM20 (I538T-Rbm20) variant does not cause DCM phenotype, but changes the gene splicing and expression effect. The splicing and expression changes in Ttn and Ca handling genes such as Casq1, Camk2d and Ryr2 may be contributory to sudden arrhythmogenic death. Overall design: Using the CRISPR/Cas system, we generated KI mice harboring the c.T1613C (p.I538T) point mutation in the mouse Rbm20 gene, which corresponded to human c.T1607C (p.I536T).