Spatial correlation was observed between the localization of laminin-1 at the inner limiting membrane (ILM) and extensive Muller glial process arborization in the same area, as demonstrated by immunolabeling of Muller glial processes and laminin-1 in rat retinae in situ. To test if this spatial correlation is due to a functional relationship, we investigated the impact of laminin-1 on the motility of cultured primary rat and mouse retinal Muller glial cells by statistical analysis of computer-controlled videomicroscopic time-lapse images. We demonstrate that laminin-1 increases motility and path-searching activity of Muller cells in vitro and it also enhances the cells' process formation/withdrawal dynamism. The increase in path-searching activity and cell process dynamism indicates that there is a functional relationship between laminin-1 and Muller glial cells presumably involving signaling towards the cytoskeleton. We hypothesize that laminin-1 is involved in process arborization of Muller cells at the vitread border of the retina resulting in the formation of the functional barrier made up of Muller glial endfeet.
Copyright 2002 Wiley-Liss, Inc.