Preserved Left Ventricular Function despite Myocardial Fibrosis and Myopathy in the Dystrophin-Deficient D2.B10-Dmd mdx /J Mouse.

Duchenne muscular dystrophy involves an absence of dystrophin, a cytoskeletal protein which supports cell structural integrity and scaffolding for signalling molecules in myocytes. Affected individuals experience progressive muscle degeneration that leads to irreversible loss of ambulation and respiratory diaphragm function. Although clinical management has greatly advanced, heart failure due to myocardial cell loss and fibrosis remains the major cause of death. We examined cardiac morphology and function in D2.B10-Dmd mdx /J (D2-mdx) mice, a relatively new mouse model of muscular dystrophy, which we compared to their wild-type background DBA/2J mice (DBA/2). We also tested whether drug treatment with a specific blocker of mitochondrial permeability transition pore opening (Debio-025), or ACE inhibition (Perindopril), had any effect on dystrophy-related cardiomyopathy. D2-mdx mice were treated for six weeks with Vehicle control, Debio-025 (20 mg/kg/day), Perindopril (2 mg/kg/day), or a combination (n = 8/group). At 18 weeks, compared to DBA/2, D2-mdx hearts displayed greater ventricular collagen, lower cell density, greater cell diameter, and greater protein expression levels of IL-6, TLR4, BAX/Bcl2, caspase-3, PGC-1α, and notably monoamine oxidases A and B. Remarkably, these adaptations in D2-mdx mice were associated with preserved resting left ventricular function similar to DBA/2 mice. Compared to vehicle, although Perindopril partly attenuated the increase in heart weight and collagen at 18 weeks, the drug treatments had no marked impact on dystrophic cardiomyopathy.

Identification, amplification and characterization of miR-17-92 from canine tissue.

Recently, a novel group of genes encoding small RNA molecules, termed microRNAs (miRNAs), has been discovered to play a vital role in eukaryotic gene expression. Known to act in a post-transcriptional fashion, miRNAs can inhibit translation by binding to messenger RNA (mRNA) or by targeting mRNA for degradation. A search of genetic databases revealed significant conservation of miRNA genes between the domestic dog and the human. This finding suggests that expression patterns may also be conserved. Proof of principle experiments, including serial dilutions and sequencing, were performed to verify that primers made to amplify human mature miRNAs can be used to amplify canine miRNAs, providing that the mature sequences are conserved. TaqMan Real-time PCR techniques were used to isolate the first miRNA mature products from canine tissues. The expression levels of miR-17-3p, miR-17-5p, miR-18, miR-19a, miR-19b, miR-20, and miR-92 were evaluated in five canine tissues (heart, lung, brain, kidney, and liver) using the delta-delta Ct (critical threshold) method.

Identification of microsatellite markers linked to progressive retinal atrophy in American Eskimo Dogs.

OBJECTIVE: To identify microsatellite markers linked to progressive retinal atrophy (PRA) in American Eskimo Dogs. SAMPLE POPULATION: Blood samples or buccal epithelial cells from 66 American Eskimo Dogs, including 53 PRA-unaffected and 13 PRA-affected dogs. PROCEDURE: The genotypes of unaffected and affected dogs were determined by use of microsatellite markers spanning canine chromosome 9 (CFA09). Homozygosity mapping was used to detect linkage between markers and the gene locus for PRA. RESULTS: Significant allelic association between marker alleles and the gene locus for PRA was detected for GALK1 and TK1, indicating linkage between these markers and the causative gene locus for PRA. CONCLUSIONS AND CLINICAL RELEVANCE: These data indicate that PRA in American Eskimo Dogs is located on CFA09 and allow for the development of a microsatellite-based test to identify carrier (unaffected) and affected dogs before clinical signs appear.