Involvement of RhoA, ROCK I and myosin II in inverted orientation of epithelial polarity.
In multicellular epithelial tissues, the orientation of polarity of each cell must be coordinated. Previously, we reported that for Madin-Darby canine kidney cells in three-dimensional collagen gel culture, blockade of beta1-integrin by the AIIB2 antibody or expression of dominant-negative Rac1N17 led to an inversion of polarity, such that the apical surfaces of the cells were misorientated towards the extracellular matrix. Here, we show that this process results from the activation of RhoA. Knockdown of RhoA by short hairpin RNA reverses the inverted orientation of polarity, resulting in normal cysts. Inhibition of RhoA downstream effectors, Rho kinase (ROCK I) and myosin II, has similar effects. We conclude that the RhoA-ROCK I-myosin II pathway controls the inversion of orientation of epithelial polarity caused by AIIB2 or Rac1N17. These results might be relevant to the hyperactivation of RhoA and disruption of normal polarity frequently observed in human epithelial cancers.
Yu
Wei
W
Department of Anatomy, Neurology, University of California, San Francisco, California 94143, USA. wei.f.yu@ucsf.edu
Shewan
Annette M
AM
Brakeman
Paul
P
Eastburn
Dennis J
DJ
Datta
Anirban
A
Bryant
David M
DM
Fan
Qi-Wen
QW
Weiss
William A
WA
Zegers
Mirjam M P
MM
Mostov
Keith E
KE
D000818:Animals; D015153:Blotting, Western; D002460:Cell Line; D016764:Cell Polarity; D004847:Epithelial Cells / Q000166:cytology / Q000378:metabolism*; D006801:Humans; D024462:Myosin Type II / Q000235:genetics / Q000378:metabolism*; D034741:RNA, Small Interfering / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014162:Transfection; D054460:rho-Associated Kinases / Q000235:genetics / Q000378:metabolism*; D020742:rhoA GTP-Binding Protein / Q000235:genetics / Q000378:metabolism*
D034741:RNA, Small Interfering; D054460:rho-Associated Kinases; D024462:Myosin Type II; D020742:rhoA GTP-Binding Protein