Role of the Polarity Protein Scribble for Podocyte Differentiation and Maintenance
Figure 3
Schematic illustration of the translocation of polarity proteins during podocyte differentiation.
During podocyte differentiation the cell-cell contacts translocate from the apical site along the lateral membrane to basal, where primary processes and foot processes develop. Par3 localizes to the cell-cell contacts, moves with them to basal and localizes to the cell-cell contact of mature podocytes, the slit diaphragm, which bridges the filtration slit between foot processes. Scribble localizes basal of Par3 at the cell-cell junctions and the basolateral membrane of immature podocytes. In mature podocytes Scribble localizes to the basolateral membrane, which is defined as the area beneath the slit-diaphragm. Differentiation of podocytes is accompanied with an enlargement of the apical membrane area, marked by Podocalyxin, whose expression starts parallel with the translocation of the cell-cell contacts to basal in s-shaped body stage. Relative to this apical membrane enlargement the basolateral membrane, marked by Scribble, shrinks to the area beneath the slit-diaphragm in mature podocytes.