Fig 2: Immunofluorescent staining of RNF207 in canine cardiac tissue. Healthy canine non-Dobermann cardiac tissue (top three rows) was stained for RNF207 to detect the differences in the expression or localization associated with disease and genotype. Additionally, tissue was stained for Hoechst in blue to show the nuclei and for actinin alpha 2 (ACTN2) in green to visualize the sarcomere structures. Localization is indicated from a transversal and longitudinal perspective. RNF207 is expressed in the cytoplasm of cardiomyocytes, intercalated disks (arrows), and perinuclearly (asterisks). In the cardiac tissue of the single DCM case homozygous for the RNF207c.1297-1G > A variant, a patchy expression resembling cellular mosaicism was detected (bottom row)

Fig 3: Immunofluorescent staining of RNF207 in canine cardiac tissue. Healthy canine non-Dobermann cardiac tissue (top three rows) was stained for RNF207 to detect the differences in the expression or localization associated with disease and genotype. Additionally, tissue was stained for Hoechst in blue to show the nuclei and for actinin alpha 2 (ACTN2) in green to visualize the sarcomere structures. Localization is indicated from a transversal and longitudinal perspective. RNF207 is expressed in the cytoplasm of cardiomyocytes, intercalated disks (arrows), and perinuclearly (asterisks). In the cardiac tissue of the single DCM case homozygous for the RNF207c.1297-1G > A variant, a patchy expression resembling cellular mosaicism was detected (bottom row)

Fig 4: Alternative splicing and potentially damaging human variants in RNF207. The position of the canine RNF207 splice variant (chr5:60,111,983G > A) is indicated with a red triangle. a Exon-intron structure of the canine RNF207 transcript (ENSCAFT00000037199.3). b The location of the variant at the splice acceptor site of exon 13 (ENSCAFT00000037199.3:c.1297-1G > A, r.1297_1305del). c Representative chromatograms of RNF207 cDNA in Dobermanns with different chr5:60,111,983 genotypes. The first nine bases of exon 13 are skipped in dogs with at least one copy of the A allele. d The average read depth and coverage at the variant site in the mRNA-seq data of the same Dobermanns as in c. Reads without the first nine bases of exon 13, indicated within the dashed lines, are observed in dogs with at least one copy of the A allele. Two reads that likely comprised pre-mRNA are observed at the deletion site in the A/A dog. e A schematic representation of the canine RNF207 protein (ENSCAFP00000032663.2, E2RD18). The p.(R433_Q435del) variant is indicated with a red triangle, and positions corresponding to protein-changing, potentially damaging variants in human cardiomyopathy patients with black lines. f Coiled-coil conformation of the wild type and p.(R433_Q435del) sequences at residues 403–463 as predicted by DeepCoil2. The coiled-coil domain may be affected by the loss of residues 433–435 in the altered protein. The propensity of coiled-coil conformation and detected peaks are indicated in blue and light blue for the wild-type sequence and in red and pink for the mutated sequence