Differences between two types of integrins

Sep 21 2009

The adhesion of cells to the various components of their environment is mediated mainly by molecules known as integrins. Two integrins, α₅β₁ and α_vβ₃, mediate adhesion with fibronectin, which is present in the extracellular matrix. But why are 2 molecules involved in the adhesion to a single extracellular component? An article published on-line in Proceedings of the National Academy of Sciences (PNAS), whose main author is Pere Roca-Cusachs, an IBEC researcher, offers the first experimental answer to this question.

The article shows the functional difference between the 2 integrins, as well as their complementarity. The integrin α₅β₁ is responsible for resisting the forces of the cellular environment while at the same time maintaining the integrity of the bond between the cell and its environment. The integrin α_vβ₃, on the other hand, merely detects such forces, without exerting any additional resistance. This discovery also confirms the intuitive idea that the cell is like a microscopic machine with a capacity for detection and resistance with which it relates to its environment.

The study was carried out with fibroblasts. Specifically, we studied the adhesion of the 2 integrins with fibronectin, a protein that is essential for cellular adhesion, wound healing, and embryogenesis. The communication of the cell with its environment is also an important factor in the development of tumors, as an increase in tissue rigidity is one of the first changes detected in a tumor. As the environment becomes more rigid, the behavior of the cell can be transformed from normal to cancerous. Anticancer therapies based on the inhibition of integrins are currently available, and an understanding of the mechanisms by which integrins affect the response of tissue cells is essential in order to develop drugs that are more specific and that have fewer secondary effects.  The identification of integrin α_vβ₃ as a detector of forces makes it a candidate for consideration in the development of anticancer therapies, as its role can account for some of the malignant behavior of tumors associated with changes in rigidity.