RNA-sequencing of patients with hypertrophic cardiomyopathy or patients with aortic stenosis compared to heart healthy donors

Hypertrophic cardiomyopathy (HCM) is often associated with heterozygous mutations in sarcomeric genes. One of the most commonly affected genes encodes for myosin binding protein C (cMyBP-C, MYBPC3). Interestingly, most mutations in MYBPC3 lead to premature termination codons which could result in truncated fragments of cMyBP-C. However, truncated cMyBP-C has not been detect, but rather a reduction of total wildtype cMyBP-C. Nonsense mediated mRNA decay of mutated MYBPC3-mRNA was often hypothesized as cause for the reduced MYBPC3-expression, however it has not been shown in human patients. Therefore, we performed RNA-sequencing of MYBPC3trunc patients, AS-patients and donors, to detect if expression of regulatory proteins of the NMD is altered in the MYBPC3trunc patients. By gene set enrichment analysis (GSEA) of the presented data, we found expression of NMD components to be enriched in the MYBPC3trunc patients, which was furthermore associated with upregulation of UP-frameshift protein (UPF3B, UPF3B) which is a regulator of NMD. Overall design: We analyzed patients with hypertrophic cardiomyopathy due to truncation mutations in myosin binding protein C (cMyBP-C, MYBPC3, MYBPC3trunc, n=6) or left verntricular hypertrophy due to aortic stenosis (AS-patients, n=5) and heart healthy donors (Donor, n=5). Total RNA was extracted from left ventricular cardiac tissue ground in a cryomortar. Gene expression of the MYBPC3trunc patients was either compared to donors or to AS-patients.