I bet you think you’re pretty good at wearing the many proverbial hats in your life. I bet you can align a laser, walk your dog, change a diaper, and play in your awesome band of cell biologists. Well, integrins will put your hat-wearing to shame! Integrins are very important proteins (VIPs!) that play huge roles in adhesion, signaling, polarity, cell migration, cell division, and differentiation. Today’s image is from a paper describing new data on integrin trafficking.
Integrins are membrane proteins that interact with the environment outside of the cell to regulate cell adhesion and signaling. As part of the cell’s plasma membrane, integrins are constantly being brought into the cell and recycled back to the cell surface. Understanding this process is important—the way that integrins are recycled back to the cell’s surface (or not) can dramatically affect a cell’s ability to move, adhere to other cells, divide, and invade (in the case of cells in a tumor). A recent paper by Mai and colleagues describes a protein called RASA1 in regulating integrin recycling back to the membrane. RASA1 binds to integrin on a site where another protein called Rab21 also binds. So, these two proteins compete—Rab21 bound to integrin prevents its recycling back to the cell surface, while RASA1 binding allows integrin to traffic back to the surface. In the images above, when levels of RASA1 were reduced (bottom), cells were able to migrate more efficiently to close a “wound” scratched across a layer of cells, as compared to control cells (top). Images on the left show the wound shortly after it was created, while images on the right are four hours later.
Mai, A., Veltel, S., Pellinen, T., Padzik, A., Coffey, E., Marjomaki, V., & Ivaska, J. (2011). Competitive binding of Rab21 and p120RasGAP to integrins regulates receptor traffic and migration originally published in The Journal of Cell Biology, 194 (2), 291-306 DOI: 10.1083/jcb.201012126