Local and global dynamics of the basement membrane during branching morphogenesis require protease activity and actomyosin contractility.

Many epithelial tissues expand rapidly during embryonic development while remaining surrounded by a basement membrane. Remodeling of the basement membrane is assumed to occur during branching morphogenesis to accommodate epithelial growth, but how such remodeling occurs is not yet clear. We report that the basement membrane is highly dynamic during branching of the salivary gland, exhibiting both local and global remodeling.

Region-specific epithelial cell dynamics during branching morphogenesis.

Background: Epithelial cells of developing embryonic organs, such as salivary glands, can display substantial motility during branching morphogenesis. Their dynamic movements and molecules involved in their migration are not fully characterized.

Results: We generated transgenic mice expressing photo-convertible KikGR and tracked the movements of individual cells highlighted by red fluorescence in different regions of developing salivary glands.

EphB regulates L1 phosphorylation during retinocollicular mapping.

Interaction of the cell adhesion molecule L1 with the cytoskeletal adaptor ankyrin is essential for topographic mapping of retinal ganglion cell (RGC) axons to synaptic targets in the superior colliculus (SC). Mice mutated in the L1 ankyrin-binding motif (FIGQY(1229)H) display abnormal mapping of RGC axons along the mediolateral axis of the SC, resembling mouse mutant phenotypes in EphB receptor tyrosine kinases. To investigate whether L1 functionally interacts with EphBs, we investigated the role of EphB kinases in phosphorylating L1 using a phospho-specific antibody to the tyrosine phosphorylated FIGQY(1229) motif.

Cell-matrix adhesions in 3D.

Cells in a three-dimensional (3D) extracellular matrix environment often display different properties and behavior compared to cells cultured on a two-dimensional (2D) substrate. Recent studies characterizing the cell-matrix adhesions formed by cells within a 3D matrix have arrived at contradictory conclusions regarding the presence and composition of adhesions. Here we review this literature, and provide a comparative compilation of information found in published studies from the 3D cell-matrix adhesion field in order to identify shared and divergent conclusions and conceptually important areas that require further research.

Direct comparisons of the morphology, migration, cell adhesions, and actin cytoskeleton of fibroblasts in four different three-dimensional extracellular matrices.

Interactions between cells and the extracellular matrix are at the core of tissue engineering and biology. However, most studies of these interactions have used traditional two-dimensional (2D) tissue culture, which is less physiological than three-dimensional (3D) tissue culture. In this study, we compared cell behavior in four types of commonly used extracellular matrix under 2D and 3D conditions.