title: B1 integrin/Fak/Src signaling in intestinal epithelial crypt cell survival: integration of complex regulatory mechanisms.
abstract: The molecular determinants which dictate survival and apoptosis/anoikis in human intestinal crypt cells remain to be fully understood. To this effect, the roles of beta1 integrin/Fak/Src signaling to the PI3-K/Akt-1, MEK/Erk, and p38 pathways, were investigated. The regulation of six Bcl-2 homologs (Bcl-2, Mcl-1, Bcl-X(L), Bax, Bak, Bad) was likewise analyzed. We report that: (1) Anoikis causes a down-activation of Fak, Src, Akt-1 and Erk1/2, a loss of Fak-Src association, and a sustained/enhanced activation of p38beta, which is required as apoptosis/anoikis driver; (2) PI3-K/Akt-1 up-regulates the expression of Bcl-X(L) and Mcl-1, down-regulates Bax and Bak, drives Bad phosphorylation (both serine112/136 residues) and antagonizes p38beta activation; (3) MEK/Erk up-regulates Bcl-2, drives Bad phosphorylation (serine112 residue), but does not antagonize p38bactivation; (4) PI3-K/Akt-1 is required for survival, whereas MEK/Erk is not; (5) Src acts as a cornerstone in the engagement of both pathways by beta1 integrins/Fak, and is crucial for survival; and (6) beta1 integrins/Fak and/or Src regulate Bcl-2 homologs as both PI3-K/Atk-1 and MEK/Erk combined. Hence, beta1 integrin/Fak/Src signaling translates into integrated mediating functions of p38beta activation and regulation of Bcl-2 homologs by PI3-K/Akt-1 and MEK/Erk, consequently determining their requirement (or not) for survival.
authors.affiliation: Département d'Anatomie et de Biologie Cellulaire, Faculté de Médecine et des Sciences de la Santé, Université de Sherbrooke, Sherbrooke, QC, Canada.
authors.forename: Véronique
authors.initials: V
authors.lastname: Bouchard
authors.forename: Charlène
authors.initials: C
authors.lastname: Harnois
authors.forename: Marie-Josée
authors.initials: MJ
authors.lastname: Demers
authors.forename: Sonya
authors.initials: S
authors.lastname: Thibodeau
authors.forename: Vincent
authors.initials: V
authors.lastname: Laquerre
authors.forename: Rémy
authors.initials: R
authors.lastname: Gauthier
authors.forename: Anne
authors.initials: A
authors.lastname: Vézina
authors.forename: Dominique
authors.initials: D
authors.lastname: Noël
authors.forename: Naoya
authors.initials: N
authors.lastname: Fujita
authors.forename: Takashi
authors.initials: T
authors.lastname: Tsuruo
authors.forename: Mélina
authors.initials: M
authors.lastname: Arguin
authors.forename: Pierre H
authors.initials: PH
authors.lastname: Vachon
mesh_terms: D023102:Anoikis / Q000502:physiology*; D002470:Cell Survival / Q000502:physiology*; D002478:Cells, Cultured; D015536:Down-Regulation; D051417:Focal Adhesion Kinase 1 / Q000502:physiology*; D006801:Humans; D019012:Integrin beta1 / Q000502:physiology*; D007413:Intestinal Mucosa / Q000166:cytology / Q000502:physiology*; D020930:MAP Kinase Kinase Kinases / Q000502:physiology; D019950:Mitogen-Activated Protein Kinase 1 / Q000502:physiology; D048290:Mitogen-Activated Protein Kinase 11 / Q000502:physiology; D048052:Mitogen-Activated Protein Kinase 3 / Q000502:physiology; D015688:Oncogene Protein pp60(v-src) / Q000502:physiology*; D019869:Phosphatidylinositol 3-Kinases / Q000502:physiology; D051057:Proto-Oncogene Proteins c-akt / Q000502:physiology; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000502:physiology; D015398:Signal Transduction / Q000502:physiology*; D015854:Up-Regulation
chemical_list: D019012:Integrin beta1; D019253:Proto-Oncogene Proteins c-bcl-2; D019869:Phosphatidylinositol 3-Kinases; D051417:Focal Adhesion Kinase 1; D015688:Oncogene Protein pp60(v-src); C496050:PTK2 protein, human; C494918:AKT1 protein, human; D051057:Proto-Oncogene Proteins c-akt; D019950:Mitogen-Activated Protein Kinase 1; D048290:Mitogen-Activated Protein Kinase 11; D048052:Mitogen-Activated Protein Kinase 3; D020930:MAP Kinase Kinase Kinases