Loss of cytokeratin expression and formation of actin stress fibers in dedifferentiated MDCK-C7 cell lines.
MDCK-C7 cells dedifferentiated either by transient alkaline stress (C7F cells) or by transfection with a constitutively active mutant of the mitogen-activated protein kinase kinase MEK1 (C7caMEK1 cells) were analyzed by western blot and immunofluorescence microscopy to compare the expression of different cytokeratins, vimentin, and alpha-smooth muscle actin. Expression of all cytokeratins tested, the type II-neutral and basic cytokeratins CK5, CK7, CK8 as well as the type I-acidic keratins CK17 and CK19, was substantially reduced in dedifferentiated cell lines C7F and C7caMEK1 when compared with epithelial wild-type MDCK-C7 cells or mock-transfected MDCK-C7 cells. While vimentin expression was detected in all of the four MDCK-C7 cell lines examined, only the dedifferentiated cell lines C7F and C7caMEK1, which have been reported to express highly active ERK2, exhibited formation of alpha-smooth muscle actin-containing stress fibers. Taken together our results show that, associated with an increase in ERK2 activity, an epithelial to mesenchymal dedifferentiation occurred in both MDCK-C7F cells and caMEK1-transfected MDCK-C7 cells.
Pollack
V
V
Department of Physiology, University of Innsbruck, Austria.
Scheiber
K
K
Pfaller
W
W
Schramek
H
H
D000199:Actins / Q000378:metabolism*; D000818:Animals; D002454:Cell Differentiation; D002460:Cell Line; D003599:Cytoskeleton / Q000378:metabolism; D004285:Dogs; D004847:Epithelial Cells / Q000378:metabolism* / Q000648:ultrastructure; D018507:Gene Expression Regulation, Developmental; D007633:Keratins / Q000378:metabolism*; D007685:Kidney Tubules, Collecting / Q000378:metabolism* / Q000648:ultrastructure; D048369:MAP Kinase Kinase 1; D020929:Mitogen-Activated Protein Kinase Kinases; D017346:Protein Serine-Threonine Kinases / Q000235:genetics; D011505:Protein-Tyrosine Kinases / Q000235:genetics; D014162:Transfection; D014746:Vimentin / Q000378:metabolism
D000199:Actins; D014746:Vimentin; D007633:Keratins; D011505:Protein-Tyrosine Kinases; D017346:Protein Serine-Threonine Kinases; D048369:MAP Kinase Kinase 1; D020929:Mitogen-Activated Protein Kinase Kinases