OR05 Zebrafish dspb-/- Mutant as a Model for Non-Dilated Left Ventricular Cardiomyopathy: Exploring Cardiac Dysfunction and Exercise Modulation

Background/Objectives Zebrafish has been reported as model to study the Arrythmogenic Cardiomyopathy, which is generally associated with desmosomal gene mutations. We have identified a founder non-sense human variant in patients from our region (DSP p.Q447*) associated with left ventricle Arrythmogenic Cardiomyopathy and we have selected it for modelling in zebra fish by CRISPR/Cas9 method, choosing exon 10 as the region of homology to be mutated and obtaining the p.T449fs* variant that determines a premature stop codon. On the other hand, tert gene enables telomerase activity and telomere maintenance and mutations in this gene have been used for studying aging effects. After multiple crossings of our dspb model with tert mutants we have obtained dspb-/-tert+/- model line. Purpose Our aim was the characterization of dspb-/-tert+/- mutants, studying the impact of aging in the development of the disease. Methods The model was obtained by crossing dspb-/- and tert-/- mutants, crossing the heterozygous mutants and genotyping for the selection of the dspb-/-tert+/- mutants. The characterization of the phenotype was performed through viability assays, cardiac function measurements and gene expression assays in larvae (3 days post fertilization) young adult (8 months old) and old adult (3 years old) individuals. Results Viability assays showed that dspb-/-tert+/- mutants suffer a premature death, with much lower survival rates than the dspb-/- group (survival dspb-/- 61.3% vs dspb-/-tert+/- 35.6%, p<0.01). Larvae heart rate analysis showed no significant differences. Echocardiography in young adults showed no significant differences between dspb-/-tert+/- and dspb-/- mutants. In old adults, echocardiography showed differences in heart rate (dspb-/- 142.5 ± 15.5 vs dspb-/-tert+/ -97.5 ± 3.5, p<0.01), respiratory frequency (dspb-/- 288.7 ± 36.1 vs dspb-/-tert+/- 95 ± 49.4, p<0.01) and atrial contraction velocity (dspb-/-155.7 ± 26.09 vs dspb-/-tert+/ -227.2 ± 17.6, p<0.05). Gene expression analysis in larvae showed that dspb expression drastically decreased (dspb-/- 0.3 ± 0.1 vs dspb-/-tert+/ -0.01 ± 0.008, p<0.01). In adults, dspb expression drastically decreased in heart tissue (dspb-/- 0.4 ± 0.01 vs dspb-/-tert+/- 0.06 ± 0.004, p<0.01) and skin (dspb-/ -0.34 ± 0.02 vs dspb-/-tert+/- 0.25 ± 0.01, p<0.01). Conclusion The dspb-/-tert+/- zebrafish presented worse survival rates, lower dspb gene expression levels and worse pathological cardiac phenotype at adult stages than dspb-/- mutants, proving that age is an important factor in the development of the disease and proving that dspb-/-tert+/- zebrafish is an appropriate model to study the impact of aging.