Preliminary Observations on Skeletal Muscle Adaptation and Plasticity in Homer 2<sup>-/-</sup> Mice

oleh: Paola Lorenzon, Sandra Furlan, Barbara Ravara, Alessandra Bosutti, Gabriele Massaria, Annalisa Bernareggi, Marina Sciancalepore, Gabor Trautmann, Katharina Block, Dieter Blottner, Paul F. Worley, Sandra Zampieri, Michele Salanova, Pompeo Volpe

Format: Article
Diterbitkan: MDPI AG 2021-09-01

Deskripsi

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<sup>-/-</sup> mouse using a multifaceted approach entailing morphometry, quantitative RT-PCR (Reverse Transcription PCR), confocal immunofluorescence, and electrophysiology. Morphometry shows that <i>Soleus</i> muscle (SOL), at variance with <i>Extensor digitorum longus</i> muscle (EDL) and <i>Flexor digitorum brevis</i> muscle (FDB), displays sizable reduction of fibre cross-sectional area compared to the WT counterparts. In SOL of Homer 2<sup>-/-</sup> mice, quantitative RT-PCR indicated the upregulation of <i>Atrogin-1</i> and <i>Muscle ring finger protein 1 (MuRF1)</i> genes, and confocal immunofluorescence showed the decrease of neuromuscular junction (NMJ) Homer content. Electrophysiological measurements of isolated FDB fibres from Homer 2<sup>-/-</sup> 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 <i>status</i> in a muscle specific fashion.