Fig. 5. Upregulation of epithelial and loss of mesenchymal characteristics in differentiated mutant MPC cells. (A,B) Distribution of the intermediate filament protein vimentin in wild-type (+/+) and mutant (-/-) differentiated MPC cells. Note that high levels of vimentin protein are expressed by wild-type MPC cells (A) and localised in cellular processes (inset in A). Mutant MPC cells express much lower levels or no vimentin (B). (C,D) Redistribution of the tight junction protein ZO-1 to cellular processes in differentiated wild-type MPC cells (see, for example, C, arrowhead). This redistribution is disrupted in MPC mutant cells (D). Note the rather homogenous ZO-1 distribution in cell membranes of mutant MPC cells. (E) Semi-quantitative RT-PCR analysis of several markers for mesenchymal and/or epithelial cell states. Vim: Expression of the intermediate filament protein vimentin is disrupted in MPC mutant cells (compare with B). ZO-1: Only one ZO-1 isoform is expressed by wild-type MPC cells, whereas both ZO-1 isoforms (± 
motif) are expressed by mutant MPC cells. DscI2: Expression of the epithelial desmosomal cadherin protein desmocollin type 2 is downregulated in wild-type MPC cells, but is maintained in mutant MPC cells. Slug: Expression of slug is disrupted in mutant MPC cells, whereas it is upregulated in wild-type MPC cells. Gpdh: Glyceraldehyde-3-phosphate dehydrogenase was used to normalise RNA content of samples.
