May 7, 2019
Keio University School of Medicine
St. Marianna University School of Medicine
Professor Michisuke Yuzaki from the Department of Physiology, Keio University School of Medicine, Assistant Professor Keiji Ibata and Professor Kazuhisa Kohda from the Department of Physiology, St. Marianna University School of Medicine, and their colleagues have revealed through experiments using mice that Cbln1, a protein that creates new synapses, is secreted from lysosomes in nerve cells in response to neuronal activity.
Lysosomes are intracellular organelles containing protein-degrading enzymes and are responsible for breaking down unnecessary intracellular proteins. This study found that Cbln1 is present in lysosomes within the axons of nerve cells. It was also discovered for the first time that when neuronal activity is enhanced, the contents of lysosomes (protein-degrading enzymes and Cbln1) are secreted from the axon to the outside of the cell.
These experimental results suggest that the destruction of the extracellular environment by protein-degrading enzymes (scrap) and synapse formation by Cbln1 (build) work in concert, potentially causing synaptic reorganization in response to neuronal activity. Synaptic reorganization is the physical basis of memory and learning, and its impairment has been reported in many psychiatric disorders and neurodevelopmental disorders. The findings of this research are expected to lead to a better understanding of normal developmental mechanisms and these pathological conditions, as well as the development of new therapeutic methods.
The results of this research were published in the online early edition of the American scientific journal "Neuron" on May 6, 2019 (U.S. Eastern Time).
For the full press release, please see below.