Through joint research with the University of Tokyo and the University of California, San Diego, a research group at Tohoku University discovered a phenomenon in which muscle cells of Drosophila are remodeled on a large scale by autophagy.A new function of autophagy during the metamorphosis of insects has been revealed.
Muscle cells have special intracellular structures such as myofibrils and T-tubules (transverse tubules).When muscle cells are damaged, membrane structures such as T-tubules are also destroyed and reconstructed, and cell homeostasis is maintained.However, it is difficult to culture muscle cells in vitro, and the mechanism of reconstruction has not been fully elucidated.
This time, the research group analyzed Drosophila muscle cells using a model system.As a result, we discovered a phenomenon in which muscle cells in the abdomen are completely destroyed and then reshaped during the metamorphosis period of Drosophila.In addition, when the causative gene of myotube myopathy, which is a human hereditary muscle disease, was deleted in the muscle cells of Drosophila, abnormal muscle cell reconstitution occurred. It is said that it seems to be preserved even after undergoing biological evolution.
Genetic analysis has identified a group of genes involved in the autophagy (autophagy in which cells degrade their own proteins) pathways as genes involved in muscle cell reconstitution, and further, autophagosomes (autophagosomes). ) And Rab2, a type of low-molecular-weight G protein involved in vesicle transport, was identified as a new molecule involved in the fusion of lysosomes (hydrophagosomes).When the action of Rab2 was suppressed in muscle cells, autophagosomes abnormally accumulated in the muscle cells, and the function of the muscle cells was lost.
It is hoped that this achievement will provide a new analytical model for understanding muscle cell reconstitution in higher animals, including humans, whose analysis has been lagging behind.
