Muscle Cell Physiology

Signal transduction leading to skeletal muscle adaptation to exercise is being studied by a group of progressively independent scientists that started under the general leadership of Enrique Jaimovich.

In skeletal muscle, increased use, disuse and fiber damage are known to trigger adaptive processes. Cellular mechanisms involved in these adaptive processes are nevertheless poorly known. The process of muscle adaptation is controlled by nerve activity and by nerve-muscle interaction; it constitutes therefore a model for both plasticity and regeneration of excitable tissues.

Work in the recent years has allowed this laboratory to describe a molecular mechanism of signal transduction that transduces the electrical stimuli in the muscle fiber membrane to regulation of gene expression in the myofiber nuclei.

Presently, research has evolved to three main areas: one of them, led by Mariana Casas is the molecular mechanism of exci tation-signaling coupling in the transverse tubule membrane; a protein complex (studied by Sonja Buvinic) involving channels, receptors, scaffolding proteins and enzymes is responsible of the first step in the transduction process.

The second area of research deals with excitation-metabolism coupling; from glucose transport to the muscle fiber to mitochondria activity and expression of metabolic genes are an important part of muscle adaptation and it is altered in pathological conditions as insulin resistance. Ariel Contreras-Ferrat, Paola Llanos and Alejandra Espinosa lead different aspects of this research.

The third area of research deals with the intracellular pathways leading to gene expression and with the abnormalities in this signaling present in different models of muscle wasting such as Duchenne muscular dystrophy, cancer cachexia and aging sarcopenia.