Genetic variation in the alternative splicing regulator RBM20 is associated with dilated cardiomyopathy

Abstract

BACKGROUND Dilated cardiomyopathy (DCM) is a leading cause of heart failure and death. The etiology of DCM is genetically heterogeneous. OBJECTIVES We sought to define the prevalence of mutations in the RNA splicing protein, RBM20, in a large cohort with DCM, and to determine if genetic variation in RBM20 is associated with clinical outcomes. METHODS Subjects included in the GRADE (Genetic Risk Assessment of Defibrillator Events) study were at least 18 years of age, had an ejection fraction of ≤ 30%, and an implantable cardioverter-defibrillator (ICD). The coding region and splice junctions of RBM20 were screened in DCM subjects; two common polymorphisms in RBM20, rs942077 and rs35141404, were genotyped in all GRADE subjects. RESULTS 1465 subjects were enrolled in the GRADE study and 283 with DCM were screened for RBM20 mutations. The mean age of subjects with DCM was 58 ± 13 years, 64% were male and the mean follow up was 24.2 ± 17.1 months after ICD placement. RBM20 mutations were identified in eight subjects with DCM (2.8%). Mutation carriers had a similar survival, transplantation rate, and frequency of ICD therapy compared to non-mutation carriers. Three of eight subjects (37.5%) with RBM20 mutations had atrial fibrillation (AF) whereas 19 (7.4%) subjects without mutations had AF (p= 0.02). Among all GRADE subjects, rs35141404 was associated with AF (minor allele OR 0.62, 95% CI 0.44–0.86, p=0.006). In the subset of GRADE subjects with DCM, rs35141404 was associated with AF (minor allele OR 0.58, p=0.047). CONCLUSIONS Mutations in RBM20 were observed in approximately 3% of subjects with DCM. There were no differences in survival, transplantation rate, and frequency of ICD therapy in mutation carriers.

RBFox1-mediated RNA splicing regulates cardiac hypertrophy and heart failure

“…A number of significantly enriched binding motifs, including CELF, TIA, ASF, hnRNPL, and RBFox1/2, were identified ( Figure 1A and Supplemental Table 2). The mRNA expression levels for Celf, Tia, Asf, and Hnrnpl were not significantly changed in failing mouse hearts compared with those in normal controls ( Figure 1B); neither were expression levels for 22 other known RNA splicing regulators, including those previously implicated in cardiac RNA splicing and the pathogenesis of cardiomyopathy, such as RBM20 (18,19,25), SC35 (13), and MBNL2 (ref. 26 and Supplemental Figure 2).…”

RNA Splicing

“…To date, only mutations in the splicing factor RNA-binding motif protein 20 (RBM20) have been causally linked to heart disease. [76][77][78] The lack of splicing factors in the list of heart disease-causing genes could have multiple explanations. It could be that mutations in splicing factors are severe and embryonically lethal.…”

“…Ever since, mutations in RBM20 have been found in multiple cohorts, being responsible for 3% to 5% of all familial DCM cases. 77,78 Subsequently, a molecular mechanism that links RBM20 to alternative splicing of several pivotal cardiac genes including titin was identified by Guo et al 80 Rbm20-deficient rats with a cardiac phenotype that closely resembles the DCM in individuals with RBM20 mutations were analyzed. RNA sequencing of hearts of the Rbm20-deficient rat and a human RBM20 mutation carrier revealed a set of 30 RBM20-dependent alternatively spliced genes that were conserved between rat and human.…”

Global impact of RNA splicing on transcriptome remodeling in the heart

“…Structural proteins, such as cardiac troponin T, or important signaling molecules, such as Ca 2+ /calmodulin-dependent protein kinase (CaM kinase), are subjected to alternative splicing in heart diseases (Ramchatesingh et al, 1995;Ding et al, 2004;Xu et al, 2005). Moreover, depletion of critical splicing regulators, including SC35 and RBM20, has been found to cause dilated cardiomyopathy in mouse and rat (Ding et al, 2004;Guo et al, 2012;Linke and Bucker, 2012;Refaat et al, 2012). In addition to classic SR and hnRNP proteins, CUG-BP1 and ETR-like factors (CELF)/Bruno-like family of RNA binding proteins and muscleblind-like proteins (MBNL proteins) have also been found to regulate both cardiac development and function (Warf and Berglund, 2007;Kalsotra et al, 2010;Koshelev et al, 2010;Dasgupta and Ladd, 2012).…”