For the first time, scientists at Tohoku University have provided experimental evidence that cell stickiness helps maintain the state of being classified in the correct compartment during development. How tightly cells aggregate, known as cell adhesion, appears to be made possible by proteins that are well known for their role in the immune system.The findings were detailed in the journal Nature Communications..
Scientists have long observed the movement of unspecialized cells in a way that ensures that a group of cells directed to a particular tissue stay together. In 1964, American biologist Malcolm Steinberg proposed that cells with similar adhesiveness move into contact with each other to produce thermodynamically stable structures in order to minimize energy use. Did. This is known as the differential adhesion hypothesis.
“Many other theoretical studies emphasize the importance of differences in cell-cell adhesion to isolate cell populations and maintain boundaries between them, which is the epithelial tissue of living animals. It hasn’t been proven yet, “says Elina Kuranaga, a laboratory at Tohoku University, for the tissue developmental dynamics that led the study. “Our study has shown for the first time that cell sorting is regulated by changes in adhesion.”
Kuranaga and her team conducted experiments on fruit fly pupae and discovered that a gene called Toll-1 plays a major role in this attachment process.
As the Drosophila grows from an immature larval stage to a mature adult, epithelial tissue-forming cells called tissue blasts gather in several “nests” of the abdomen. Each nest contains anterior and posterior compartments. Tissue blasts are destined to replace larval cells and form the outermost layer of the fly, the epidermis of adults. The cells in each compartment form separate cell populations, so they need to form clear boundaries between them and stick them together.
Using fluorescent tags, Cranaga and her team observed that the Toll-1 protein was expressed primarily in the posterior compartment. Its fluorescence also showed a sharp boundary between the two compartments.
Further investigation has shown that Toll-1 acts as an adhesion molecule, encouraging similar cells to stick to each other. This process keeps the boundaries between the two compartments straight and corrects the strain that occurs as cells divide and increase in number.
Interestingly, tall proteins are best known for recognizing invading pathogens, and little is known about their function beyond the immune system. “Our work improves our understanding of the non-immune role of tall proteins,” says Kuranaga. She and her team then plan to study the function of other tall genes in fruit fly epithelial cells.
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