Homer represents a diversified family of scaffold and transduction proteins made up of
several isoforms. Here, we present preliminary observations on skeletal muscle adaptation and
plasticity in a transgenic model of Homer 2-/- mouse using a multifaceted approach entailing morphometry,
quantitative RT-PCR, confocal immunofluorescence, and electrophysiology. Morphometry
shows that Soleus muscle (SOL), at variance with Extensor digitorum longus muscle (EDL) and
Flexor digitorum brevis muscle (FDB), displays sizable reduction of fibre cross-sectional area compared
to the WT counterparts. In SOL of Homer 2-/- mice, quantitative RT-PCR indicated the upregulation
of Atrogin-1 and Muscle ring finger protein 1 (MuRF1) genes, and confocal immunofluorescence
showed the decrease of neuromuscular junction (NMJ) Homer content. Electrophysiological
measurements of isolated FDB fibres from Homer 2-/- mice detected the exclusive presence of the
adult ε-nAChR isoform excluding denervation. As for NMJ morphology, data were not conclusive,
and further work is needed to ascertain whether the null Homer 2 phenotype induces any endplate
remodelling. Within the context of adaptation and plasticity, the present data show that Homer 2 is
a co-regulator of the normotrophic status in a muscle specific fashion.
