Research by scientists at Cancer Research UK's London Research Institute (LRI; now part of the Francis Crick Institute) offers a possible explanation for how human tissues such as skin grow in response to stretching forces.
Dr Barry Thompson's group at LRI found a new function for the Spectrin cytoskeleton - the lesser known of three types of cytoskeleton. Cytoskeletons are the networks in cells that provide structure, shape and help with cell movement. Dr Thompson's group found that the Spectrin cytoskeleton also plays a role in sensing forces and regulating tissue growth.
It was already known that Spectrin proteins associate closely with the inside surface of a cell's plasma membrane (which separates the contents of the cell from the outside environment). It was also known that Spectrins can form spring-like networks that can stretch under force. The team has now shown that cells can use the Spectrin cytoskeleton to regulate cell multiplication and growth in response to outside forces.
The scientists removed the genes for Spectrin in the fruit fly Drosophila and looked at how this affected tissue growth. They also used a technique called RNA interference to turn off the Spectrin genes in Drosophila and human epithelial cells.
Their results revealed that, in normal cells under normal conditions, Spectrins keep cell growth levels low through a molecular pathway known as Hippo. However when there is tension exerted on the cells, Spectrins no longer activate the Hippo pathway and cells begin to grow and divide.
Dr Thompson said: "Our findings suggest a new way in which cells can sense external forces applied to them, and can then use this information to regulate their behaviour.
"The growth of human tissues such as skin is known to be stimulated by stretching forces, so our results suggest a possible mechanism to explain how this works."
The paper, The Spectrin cytoskeleton regulates the Hippo signalling pathway, is published inThe EMBO Journal.
