Professor Lucia Tabares from the department of Medical Physiology and Biophysics at the University of Seville in Spain was awarded an SMA Europe grant to study calcium homeostasis in SMN-deficient motor neurons.
Professor Tabares trained in Electrophysiology and Imaging, from ion channels function to neurotransmission. After medical school, she obtained her Ph.D. through the discovery that adrenal cortical cells are electrically excitable. As a postdoc, she worked on the calcium channels permeation mechanisms with Clay Armstrong at the University of Pennsylvania and the MBL at Woods Hole (USA). During a second postdoc, at the laboratory of David Clapham at the Mayo Clinic (Rochester, MN), she characterised two chloride channels at the cell nucleus membrane. In 2002, she returned to her lab in Spain and started work on SMA. Since then, she has been committed to investigating the neurotransmission defects and the synaptic morphological alterations in this disease and in others mouse models of synaptopathies. In parallel, and in collaboration with Prof. Bill Betz (Univ. of Colorado, USA), she contributed to the understanding of how active zones organisation relates to synaptic transmission regulation. Thet also performed live imaging of the exo-endocytosis dynamics at motor nerve terminals in synaptopHluorin transgenic mice. Professor Tabares was promoted to Professor in 2009.
Her lab is interested in synaptic function. They investigate the dynamics of quanta release and vesicle replenishment at the motor nerve terminal, as well as the pathogenic mechanisms in diseases where the synapse undergoes degenerative processes such as in SMA. For the study of both synaptic function and dysfunction they combine molecular, electrophysiological, and optical tools and use genetic mouse models. At present, they are investigating exo- and endocytosis in real-time in motor nerve terminals and are studying the role of the mitochondria as a calcium buffer system to modulate cell calcium homeostasis in health and disease.
Low levels of the survival motoneuron (SMN) protein causes spinal muscular atrophy (SMA), a devastating neuromuscular disease characterised by motoneuron loss and muscle weakness. What causes the loss of motor neurons is still debated but in SMA, several pieces of evidence signal that cellular calcium (Ca2+) homeostasis is altered. Calcium plays an important role in the ability of motor neurons to transmit signals to muscle cells.
Professor Tabares will investigate to what extend Ca2+ homeostasis is perturbed, the mechanisms implicated, and how Ca2+ dysregulation contributes to the pathogenesis of the disease. She will also test the effectiveness over Ca2+ homeostasis and cell survival of compounds that regulate cell electrical activity. This project will allow Professor Tabares to integrate distinct aspects of the pathophysiology of motoneurons at the level of the cell membrane, the cytosol, and the mitochondria (the cell’s power house) and explore new therapeutic opportunities to protect motor neurons in SMA, in conjunction with SMA-restoring strategies. This has formed the basis of Riluzole in ALS/ MND therapeutics.
Dr. Christian Simon from Leipzig University is currently a group leader at the Carl-Ludwig-Institute for Physiology as a part of Professor Stefan Hallermann’s laboratory. Dr. Simon’s group studies the mechanisms of neuronal death and dysfunction in motor neuron diseases. During his Masters and PhD, under the supervision of Professor Michael Sendtner at the University of Würzburg, Dr. Simon studied the beneficial effects of neurotrophic factors in SMA mouse models by applying molecular and imaging techniques. In 2012, he joined Prof. George Mentis’ group at Columbia University as a Postdoc, to study neuronal circuitry dysfunction in the spinal cord of SMA mice and stem cell-derived motor neurons. By applying intracellular recordings combined with high resolution microscopy, Dr. Simon could identify novel mechanistic insights of neuronal death and the important contribution of proprioceptive neurons during SMA disease progression. In 2013, he received the Roche Young Investigator Award for neurological research. After his return to Germany in 2017, a grant from the German Research Council allowed him to start his own group in Leipzig.
Dr. Christian Simon has been granted an SMA Europe award to investigate how proprioceptive synapses degenerate and how their function could be improved, which may aid the discovery of novel therapeutic strategies in humans.
Muscle shrinkage and paralysis are the most prominent physical features of SMA patients. Motor neurons that control muscle function are increasingly lost in this disease, which was the main focus of SMA research for decades. However, Dr. Simon and his team recently showed that proprioceptive neurons, which receive spatial information from the muscle and in turn activate motor neurons for proper movement, contribute to SMA immobility.
In this proposal, Dr. Simon will explore, in mice, whether proprioceptive neurons can be used as a non-invasive, functional biomarker of the disease progression in SMA patients before and during treatment. Furthermore, he will investigate how proprioceptive synapses degenerate and how their function can be improved, in mice.
Dr. Simon’s work may aid the discovery of novel therapeutic strategies for people living with SMA.