Laminins in Epithelial Cell Polarization: Old Questions in Search of New Answers.
Laminin, a basement membrane protein discovered in 1979, was shortly thereafter implicated in the polarization of epithelial cells in both mammals and a variety of lower organisms. To transduce a spatial cue to the intrinsic polarization machinery, laminin must polymerize into a dense network that forms the foundation of the basement membrane. Evidence suggests that activation of the small GTPase Rac1 by β1-integrins mobilizes laminin-binding integrins and dystroglycan to consolidate formation of the laminin network and initiate rearrangements of both the actin and microtubule cytoskeleton to help establish the apicobasal axis. A key coordinator of spatial signals from laminin is the serine-threonine kinase Par-1, which is known to affect dystroglycan availability, microtubule and actin organization, and lumen formation. The signaling protein integrin-linked kinase (ILK) may also play a role. Despite significant advances, knowledge of the mechanism by which assembled laminin produces a spatial signal remains fragmentary, and much more research into the complex functions of laminin in polarization and other cellular processes is needed.
Department of Surgery, The University of Chicago, Chicago, Illinois 60637-1470.
Karl S
KS
Matlin
Biocenter Oulu, Oulu Center for Cell-Matrix Research, Faculty of Biochemistry and Molecular Medicine, University of Oulu, Oulu 90220, Finland.
Satu-Marja
SM
Myllymäki
Biocenter Oulu, Oulu Center for Cell-Matrix Research, Faculty of Biochemistry and Molecular Medicine, University of Oulu, Oulu 90220, Finland.
Aki
A
Manninen
D000818:Animals; D016764:Cell Polarity; D004847:Epithelial Cells / Q000502:physiology*; D007797:Laminin / Q000502:physiology*
D007797:Laminin