When cells adhere to and interact with their surroundings in tissues, they generate and transmit molecular signals that control how the cells behave, such as whether they move, grow or divide. Molecules that carry these signals are often modified temporarily to switch the signals on or off. One important type of biochemical modification is phosphorylation, which plays a role in many cell signalling processes, including cell adhesion.
Adhesion signalling molecules activated by phosphorylation
Integrins are a family of adhesion proteins that interact with and sense neighbouring cells and the surrounding extracellular environment. They project from the surface of cells like antennae and transmit signals back and forth between the cell and its surroundings – this signalling controls a wide range of important cellular functions.
A network of cell adhesion proteins in the constellation of the proteome
Amazingly, to signal, the integrin molecules change shape in the cell membrane, twisting from a compact “inactive” position to an extended “active” position. Depending on the shape of the integrins, different proteins attach to them to assist in the signalling process. But which proteins bind to different conformations of integrins, and how does this change the behaviour of a cell in response to its surroundings?
Cells are connected to their surroundings by cell adhesion complexes, collections of interacting proteins that transmit cellular signals between the outside and the inside of the cell. This signalling allows a cell to sense its environment and respond in remarkable ways, such as by moving, secreting proteins or changing into a different type of cell. But how do cell adhesion complexes receive and integrate these cellular signals?
Network of adhesion complex changes upon cytoskeletal disruption
Kidneys perform the vital role of filtering waste products from the blood. Yet the complete catalogue of constituents that comprise these filters is not known. In new work, analyses of extracellular proteins present in specialised filtration units called glomeruli reveal a composition far more complex than previously appreciated.
Extracellular proteins of the glomerulus
The movement of cells in the body is of great importance to our lives. For us to learn a language, to fight a cold, to heal a wound, to grow a pair (of arms, say), cells must migrate to the right place at the right time. So cell migration must be tightly controlled – throughout our entire lives.
Cells have many in-built control mechanisms that ensure their appropriate movement, but we still don’t fully understand how these various mechanisms operate.
In new work, published in the Journal of Cell Science this week, Guillaume Jacquemet and others identify a way that cells can coordinate proper cell migration. The research is highlighted by the journal editors and features on the cover of the journal.
Journal of Cell Science cover, 2013, vol. 126 (no. 18)
Adam Byron 