title: RhoG regulates anoikis through a phosphatidylinositol 3-kinase-dependent mechanism.
abstract: In normal epithelial cells, cell-matrix interaction is required for cell survival and proliferation, whereas disruption of this interaction causes epithelial cells to undergo apoptosis called anoikis. Here we show that the small GTPase RhoG plays an important role in the regulation of anoikis. HeLa cells are capable of anchorage-independent cell growth and acquire resistance to anoikis. We found that RNA interference-mediated knockdown of RhoG promoted anoikis in HeLa cells. Previous studies have shown that RhoG activates Rac1 and induces several cellular functions including promotion of cell migration through its effector ELMO and the ELMO-binding protein Dock180 that function as a Rac-specific guanine nucleotide exchange factor. However, RhoG-induced suppression of anoikis was independent of the ELMO- and Dock180-mediated activation of Rac1. On the other hand, the regulation of anoikis by RhoG required phosphatidylinositol 3-kinase (PI3K) activity, and constitutively active RhoG bound to the PI3K regulatory subunit p85alpha and induced the PI3K-dependent phosphorylation of Akt. Taken together, these results suggest that RhoG protects cells from apoptosis caused by the loss of anchorage through a PI3K-dependent mechanism, independent of its activation of Rac1.
authors.affiliation: Laboratory of Molecular Neurobiology, Graduate School of Biostudies, Kyoto University, Kyoto, Japan.
authors.forename: Nao
authors.initials: N
authors.lastname: Yamaki
authors.forename: Manabu
authors.initials: M
authors.lastname: Negishi
authors.forename: Hironori
authors.initials: H
authors.lastname: Katoh
mesh_terms: D048868:Adaptor Proteins, Signal Transducing / Q000378:metabolism; D000595:Amino Acid Sequence; D000818:Animals; D023102:Anoikis / Q000235:genetics; D001483:Base Sequence; D002465:Cell Movement; D002867:Chromones / Q000494:pharmacology; D006367:HeLa Cells; D006801:Humans; D051379:Mice; D008969:Molecular Sequence Data; D009025:Morpholines / Q000494:pharmacology; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism*; D000081082:Phosphoinositide-3 Kinase Inhibitors; D010766:Phosphorylation; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D034622:RNA Interference; D034741:RNA, Small Interfering / Q000494:pharmacology; D020744:rac GTP-Binding Proteins / Q000378:metabolism; D020830:rac1 GTP-Binding Protein / Q000378:metabolism; D020741:rho GTP-Binding Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D002867:Chromones; D009025:Morpholines; D019869:Phosphatidylinositol 3-Kinases; D000081082:Phosphoinositide-3 Kinase Inhibitors; D051057:Proto-Oncogene Proteins c-akt; D034741:RNA, Small Interfering; D020744:rac GTP-Binding Proteins; D020830:rac1 GTP-Binding Protein; D020741:rho GTP-Binding Proteins; C099818:DOCK1 protein, human; C465214:ELMO1 protein, human; C075397:RHOG protein, human; C085911:2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one