THE ROLE OF ACTIN-BINDING PROTEINS IN EPITHELIAL MORPHOGENESIS - MODELS BASED UPON LISTERIA MOVEMENT

We summarize recent findings on the organization of the protein actin in eucaryotic cells. In particular we focus on how actin can be used t o generate a vectorial force that is required for cell movement. These forces arise from protein molecules that recruit actin to the plasma membrane in such a manner that actin filaments extend outward from the cell body. This type of actin dependent force generation has been des cribed in a nucleation-release model, which is one of several models c urrently being tested to explain actin dependent cell movement. Data i n support of this model has arisen unexpectedly from studies of an int racellular bacteria, Listeria monocytogenes. This bacteria uses actin to propel itself during infection of eucaryotic cells. By studying Lis teria movement, the roles of several eucaryotic actin interacting prot eins have been identified. One of these is zyxin, a human protein that shares important structural and possibly functional properties with A ctA, an actin dependent force generating protein of Listeria. We inten d to test the function of these and other actin interacting proteins i n a simplified system that should facilitate precise measurement of th eir properties of force generation in vitro. (C) 1997 Elsevier Science B.V.