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Mechanisms for luminal cell filling induced by active Rac 1 and K‐Ras
Author(s) -
Kiyokawa Etsuko
Publication year - 2012
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.26.1_supplement.657.15
Subject(s) - rac1 , rhoa , cdc42 , microbiology and biotechnology , cell polarity , gtpase , cell , förster resonance energy transfer , chemistry , rac gtp binding proteins , cell migration , cell cortex , cell membrane , small gtpase , cell division , biophysics , biology , cytoskeleton , signal transduction , biochemistry , fluorescence , physics , quantum mechanics
It has been reported that Rho‐family small GTPases play important roles in cell polarity and cell migration in two‐dimensional environment. However, it has not been shown when and where the GTPases are activated in 3‐dimensional epithelial structures. Based on the principal of Foerster (or Fluorescence) resonance energy transfer (FRET), we visualized the spatio‐temporal changes of RhoA, Rac1, and Cdc42 activity during cysto‐ and tubulo‐genesis of MDCK cells. We found Rac1 activity is homogenous at the entire plasma membrane in early stages of cystogenesis, whereas in later stages Rac1 activity is higher at the lateral than the apical plasma membrane. If Rac1 is activated at the apical membrane in later stages, however, the monolayer cells proliferate into the luminal space. In these cells, tight junctions are disrupted, resulting in mislocalization of polarization markers and disorientation of cell division. These observations indicate that Rac1 suppression at the apical membrane is essential for the maintenance of cyst structure. We also found that the active variant of KRas induced similar luminal cell filling, however, the cell division was not accompanied with this Ras‐induced phenotype. These results suggest that Rac and Ras utilize different mechanism to induce similar phenotypes.