Cells need a constant source of energy to function properly.
But how do cells maintain their energy supply when a person is starving?
Scientists studying X-chromosome-linked central nuclear myopathy (XLCNM) have found a new mechanism and published the results in the journal Science.
XLCNM is a myotonic dystrophy disorder with symptoms of impaired skeletal muscle development.
This genetic disorder is caused by a defect in the MTM1 gene, which encodes myotubularin that mediates signaling in the endosome (nucleus) of cells.
The researchers compared the internal structure of normal and patient myogenic cells.
It was found that normal cells can balance two forms of endoplasmic reticulum, forming closed flattened vesicles around the nucleus and tiny membrane tubes at the periphery of the cell
In contrast, myofibroblasts from XLCNM patients have more membrane tubes, and the flattened capsule cannot be closed because of the reduced membrane component.
When the body is starved and the cells are deprived of amino acids, the enzyme encoded by MTM1 regulates the connection between the inner nucleus and the peripheral membranous tubules, which are reduced.
The membrane tubules are converted into flattened vesicles to replenish the membrane component, allowing the flattened vesicles to fuse with the mitochondria to form a larger mitochondrion, which helps to increase the efficiency of fat metabolism for energy supply.
However, because cells with XLCNM lack the enzyme encoded by MTM1, the intranuclear bodies remain in contact with the peripheral membrane tubules during starvation, resulting in no deformation of the membrane tubules, pores in the flattened vesicles, and no enlargement of the mitochondria, which makes the cells poorly able to break down fats for energy supply, ultimately making them severely energy deficient.