Regulation of RBM20 expression and activity in cardiac development and disease

• Applicant: Professor Dr. Michael Gotthardt
• Subject Area: Cardiology, Angiology
• Term: from 2015 to 2022
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 271048839

Alternative splicing plays a major role in the regulation of gene expression and in the generation of proteome diversity. Lately it has been increasingly recognized that defects in splice factors as well as their target sites can cause human disease. Accordingly, alternative splicing has the potential to serve as a therapeutic target for various inherited diseases of the central nervous system, heart, and skeletal muscle. We have recently established RNA binding motif protein 20 (RBM20) as a regulator of cardiac splicing with a broad substrate spectrum that includes titin. Mutations in RBM20 result in severe forms of human dilated cardiomyopathy (DCM) with deregulation of several alternatively spliced transcripts that contribute to the disease state. As RBM20 modulates splicing of select substrates that orchestrate both electrical and mechanical cardiac function, an RBM20 directed therapy is expected to improve diverse aspects of cardiac pathology.The clinical relevance of RBM20 deficiency and its substrate spectrum have been described in the past five years and we are only beginning to understand its regulation on the RNA and protein level. Thus, little is known about the regulation of RBM20 expression, about the interactions of RBM20 with the basic splicing machinery, about the modulation of its splicing activity, and about the underlying mechanisms by which mutations in RBM20 contribute to cardiac pathology. To dissect the molecular functions of RBM20, to understand its regulation and to develop RBM20 as a therapeutic target, we propose the following aims:Aim 1: Regulation of RBM20 expressionHypothesis: The expression of RBM20 is spatially and temporally regulated to adapt titin isoform expression in developing and diseased striated muscleTest 1.1: Physiological RBM20 RNA and protein expression.Test 1.2: RBM20 levels in cardiac remodeling and disease.Test 1.3: Characterization of the human RBM20 promoter.Test 1.4: Pharmacological modulation of RBM20 transcript levels.Aim 2: Regulation of RBM20-mediated splicingHypothesis: RBM20 regulates alternative splicing through specific interactions with RNA and components of the splicing machineryTest 2.1: The molecular and mechanistic basis of RBM20-dependent splicing.Test 2.2: RBM20 protein domains involved in the regulation of alternative splicing.Aim 3: Functional consequences of RBM20 mutationsHypothesis: Mutations of RBM20 that are linked to DCM alter function, stability or localization of the proteinTest 3.1: Protein homeostasis of mutant RBM20.Test 3.2: Nuclear localization, RNA binding and splicing regulation of mutant RBM20.

• DFG Programme: Research Grants