Similar to the human circulatory system or lungs, the fruit fly’s tracheal system consists of a network of tubes. During the embryonic development of these insects, this network of tubes is filled with a special substance that gives them shape (an extracellular matrix), which is secreted by the surrounding cells. As the organs grow, the cells are closely connected to this extracellular matrix and “shimmy” along it to form the right shape and size of tubes.
The forces between the cells and the extracellular matrix shift during this time, for example due to strong cell growth. This could lead to deformation of the cell membranes because the overlying matrix cannot expand with them. When this happens, the protease Notopleural comes into play. This is an enzyme that cleaves proteins or peptides. The enzyme acts like a pair of scissors, cutting up the Piopio protein and breaking the cell-matrix bonds. “This trick avoids excessive tension and deformation of the cell membranes. If this does not happen, bumps and cracks form in the tube system and the fruit fly’s respiratory system does not function,” says Dr Matthias Behr, senior author of the study.
He explains that similar defects occur in the human circulatory system in the form of aortic aneurysms. Since the proteins that Behr and his colleagues have identified in their study in the fruit fly are also present in very similar form in humans, the mechanism described could support future research into the cause of aortic aneurysms and similar tubular diseases.
eLife
Experimental study
Animals
The proteolysis of ZP proteins is essential to control cell membrane structure and integrity of developing tracheal tubes in Drosophila
24-Oct-2023