Employing a new force-sensing technique, a multidisciplinary team of researchers at Stanford were able closely examine how cells connect to one another and how individual cells control their own shape and movement within larger tissues.
Their findings, which were recently published in the Proceedings of the National Academy of Sciences, could help scientists better understand how tissues and tumors form and grow and how complex living organisms organize themselves. A Stanford Report story today offers more details about the work:
At its most basic level, a cell is like a balloon filled with saltwater, [Alexander Dunn, PhD, assistant professor of chemical engineering,] said. The exterior of the cell, the balloon part, is known as the membrane. Protruding through the membrane, with portions both inside and outside the cell, are certain proteins called cadherins.
Outside of the cell, cadherins bind one cell to its neighbors like Velcro. The "herin" portion of the name, in fact, shares a Latin root with "adhere."
On the inside of the cell, cadherin is connected to long fibers of actin and myosin that stretch from membrane to nucleus to membrane again. Actin and myosin work together as the muscle of the cell, providing tension that gives the cell shape and the ability to control its own movement. Without this force, the balloon of the cell would be a shapeless, immobile blob.
While it was understood that cadherin and actin are connected to one another by other proteins known as catenins, what was not known was how, when and where the cells might be using their muscles (actin and myosin) to tug on the Velcro (cadherin) holding them to other cells.
Dunn and his colleagues have shown for the first time that the actin-catenin-cadherin structure transmits force within the cell and, further, that cadherin can convey mechanical forces from one cell to the next. This is an important problem in the development of organisms, since a cell must somehow control its shape and its attachments to other cells as it grows, divides and migrates from one place to another within the tissue.
Photo of Dunn by Norbert von der Groeben