Li, M., Andersson-Lendahl, M., Sejersen, T., and Arner, A. (2013) Knockdown of desmin in zebrafish larvae affects interfilament spacing and mechanical properties of skeletal muscle. The Journal of general physiology. 141(3):335-345.
Skeletal muscle was examined in zebrafish larvae in order to address questions related to the function of the intermediate
filament protein desmin and its role in the pathogenesis of human desminopathy. A novel approach including mechanical and
structural studies of 4–6-d-old larvae was applied. Morpholino antisense oligonucleotides were used to knock down desmin.
Expression was assessed using messenger RNA and protein analyses. Histology and synchrotron light–based small angle x-ray
diffraction were applied. Functional properties were analyzed with in vivo studies of swimming behavior and with in vitro
mechanical examinations of muscle. The two desmin genes normally expressed in zebrafish could be knocked down by <50%. This
resulted in a phenotype with disorganized muscles with altered attachments to the myosepta. The knockdown larvae were smaller
and had diminished swimming activity. Active tension was lowered and muscles were less vulnerable to acute stretch-induced
injury. X-ray diffraction revealed wider interfilament spacing. In conclusion, desmin intermediate filaments are required
for normal active force generation and affect vulnerability during eccentric work. This is related to the role of desmin in
anchoring sarcomeres for optimal force transmission. The results also show that a partial lack of desmin, without protein
aggregates, is sufficient to cause muscle pathology resembling that in human desminopathy.