The role of the cytoskeleton in renal development.

The cytoskeleton is comprised of three separate filament networks: microtubules, microfilaments, and intermediate filaments. Collectively, these networks help establish and maintain the structural features of renal epithelial cells. During renal development, the cytoskeleton of the metanephric mesenchyme is extensively reorganized in order to create the cytoarchitectural elements that distinguish tubuloepithelial cells. This reorganization is coordinated with the formation of cell-cell contacts and cell-extracellular matrix interactions that are necessary to complete the developmental program. The actin cytoskeleton, microtubule network, and intermediate filament network all contribute to the development of polarity in the renal epithelial cells. The microtubule network determines the apical-basal axis of the cell. The actin cytoskeleton integrates topographic contacts between the cells and extracellular matrix. The tight junction and microvilli are subcellular structures that are associated with or comprised of actin filaments. Intermediate filament composition changes during the embryonic transition from metanephric mesenchyme to tubular epithelial cells. This review will describe the cell biology of the cytoskeletal elements in epithelial cells and the changes in cytoskeleton that accompany the formation of differentiated epithelial cells.