Pathophysiological defects and transcriptional profiling in the RBM20-/- rat model

Area of Science:

• Cardiovascular Biology
• Molecular Genetics
• Cardiac Pathophysiology

Background:

• RNA binding motif 20 (Rbm20) is known to regulate gene splicing.
• Dysregulation of Rbm20 has been implicated in heart conditions.
• The precise molecular mechanisms linking Rbm20 to heart failure require further elucidation.

Purpose of the Study:

• To investigate the physiological, structural, and molecular consequences of Rbm20 deficiency in rats.
• To determine the impact of Rbm20 loss on titin splicing and cardiac function.
• To identify downstream molecular pathways affected by Rbm20 malfunction.

Main Methods:

• Quantitative and qualitative analysis of titin isoform expression using real-time RT-PCR and SDS agarose electrophoresis.
• Assessment of physiological parameters including exercise tolerance.
• Electron microscopy of cardiac and skeletal muscle ultrastructure.
• Analysis of gene and protein expression to identify activated pathways.

Main Results:

• Rbm20 deficiency led to significant alterations in titin splicing, primarily affecting transcription.
• Knockout rats exhibited reduced exercise endurance, suggesting impaired cardiac output or skeletal muscle function.
• Cardiac ultrastructure analysis revealed abnormal myofibril arrangement, Z line streaming, and lipofuscin accumulation in Rbm20(-/-) hearts.
• Skeletal muscle ultrastructure remained normal in knockout animals.
• Gene and protein expression data indicated activation of pathophysiological and muscle stress-activated pathways.

Conclusions:

• Splicing alterations driven by Rbm20 deficiency induce pathogenic changes in cardiac physiology and ultrastructure.
• Rbm20 malfunction is a direct cause of cardiomyopathy through disruption of titin and other gene splicing.
• The study provides novel insights into Rbm20's role in maintaining cardiac health and the consequences of its loss.