Formation of multicellular epithelial structures.
The kidney is primarily comprised of highly polarized epithelial cells. Much has been learned recently about the mechanisms of epithelial polarization. However, in most experimental systems the orientation of this polarity is determined by external cues, such as growth of epithelial cells on a filter support. When Madin-Darby canine kidney (MDCK) cells are grown instead in a three-dimensional (3D) collagen gel, the cells form hollow cysts lined by a monolayer of epithelial cells, with their apical surfaces all facing the central lumen. We have found that expression of a dominant-negative (DN) form of the small GTPase Rac1 causes an inversion of epithelial polarity, such that the apical surface of the cells instead faces the periphery of the cyst. This indicates that the establishment of polarity and the orientation of polarity can be experimentally separated by growing cells in a 3D collagen gel, where there is no filter support to provide an external cue for orientation. DN Rac1 causes a defect in the assembly of laminin into its normal basement membrane network, and addition of a high concentration of exogenous laminin rescues the inversion of polarity caused by DN Rac1.
Mostov
Keith
K
Department of Anatomy, University of California, San Francisco 94143-2140, USA.
Brakeman
Paul
P
Datta
Anirban
A
Gassama
Ama
A
Katz
Leonid
L
Kim
Minji
M
Leroy
Pascale
P
Levin
Max
M
Liu
Kathleen
K
Martin
Fernando
F
O'Brien
Lucy E
LE
Verges
Marcel
M
Su
Tao
T
Tang
Kitty
K
Tanimizu
Naoki
N
Yamaji
Toshiyuki
T
Yu
Wei
W
D000818:Animals; D002450:Cell Communication; D002460:Cell Line; D016764:Cell Polarity; D003094:Collagen; D004285:Dogs; D004847:Epithelial Cells / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism*; D017228:Hepatocyte Growth Factor / Q000494:pharmacology; D019108:Tight Junctions / Q000502:physiology; D020830:rac1 GTP-Binding Protein / Q000378:metabolism
D017228:Hepatocyte Growth Factor; D003094:Collagen; D020830:rac1 GTP-Binding Protein