Human intestinal epithelial crypt cell survival and death: Complex modulations of Bcl-2 homologs by Fak, PI3-K/Akt-1, MEK/Erk, and p38 signaling pathways.
To investigate the mechanisms responsible for survival and apoptosis/anoikis in normal human intestinal epithelial crypt cells, we analyzed the roles of various signaling pathways and cell adhesion on the expression of six Bcl-2 homologs (Bcl-2, Bcl-XL, Mcl-1, Bax, Bak, Bad) in the well established HIEC-6 cell model. Pharmacological inhibitors and/or dominant-negative constructs were used to inhibit focal adhesion kinase (Fak) and p38 isoforms, as well as the phosphatidylinositol 3'-kinase (PI3-K)/Akt-1 and mitogen-activated protein kinase [MAPK] kinase (MEK)/extracellular regulated kinases (Erk) pathways. Cell adhesion was disrupted by antibody-inhibition of integrin binding or forced cell suspension. The activation levels of studied kinase pathways were also analyzed. Herein, we report that beta1 integrins, Fak, and the PI3-K/Akt-1 pathway, but not beta4 integrins or the MEK/Erk pathway, are crucial for the survival of HIEC-6 cells. Conversely, p38beta, but not p38alpha or gamma, is required for the induction of apoptosis/anoikis in HIEC-6 cells. However, each of the signaling molecules/pathways analyzed were found to affect distinctively the individual expression of the Bcl-2 homologs studied. For example, the inhibition of the PI3-K/Akt-1 pathway down-regulated Bcl-XL, Mcl-1, and Bad, while at the same time up-regulating Bax, whereas the inhibition of Fak up-regulated both Bax and Bak, down-regulated Bad, and did not affect the other Bcl-2 homologs analyzed. These results indicate that integrins, Fak, PI3-K/Akt-1, MEK/Erk, and p38 isoforms perform distinct roles in the regulation of HIEC-6 cell survival and/or death. In addition, our data show that the functions performed by these molecules/pathways in promoting cell survival or apoptosis/anoikis translate into complex, differential modulations of individual Bcl-2 homologs.
Harnois
Charlène
C
Canadian Institutes of Health Research Group on the Functional Development and Physiopathology of the Digestive Tract, Département d'Anatomie et de Biologie Cellulaire, Faculté de Médecine, Université de Sherbrooke, Sherbrooke, Québec, Canada.
Demers
Marie-Josée
MJ
Bouchard
Véronique
V
Vallée
Karine
K
Gagné
David
D
Fujita
Naoya
N
Tsuruo
Takashi
T
Vézina
Anne
A
Beaulieu
Jean-François
JF
Côté
André
A
Vachon
Pierre H
PH
D017209:Apoptosis / Q000502:physiology*; D015153:Blotting, Western; D002448:Cell Adhesion / Q000502:physiology; D002470:Cell Survival / Q000502:physiology; D004789:Enzyme Activation; D051417:Focal Adhesion Kinase 1; D051416:Focal Adhesion Protein-Tyrosine Kinases; D006801:Humans; D016023:Integrins / Q000502:physiology; D007413:Intestinal Mucosa / Q000502:physiology*; D048728:MAP Kinase Kinase Kinase 1; D020928:Mitogen-Activated Protein Kinases / Q000502:physiology; D019869:Phosphatidylinositol 3-Kinases / Q000502:physiology; D011233:Precipitin Tests; D017346:Protein Serine-Threonine Kinases / Q000502:physiology; D011505:Protein-Tyrosine Kinases / Q000502:physiology; D011518:Proto-Oncogene Proteins; D051057:Proto-Oncogene Proteins c-akt; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000502:physiology; D015398:Signal Transduction / Q000502:physiology*; D014162:Transfection; D048051:p38 Mitogen-Activated Protein Kinases
D051417:Focal Adhesion Kinase 1; D051416:Focal Adhesion Protein-Tyrosine Kinases; D016023:Integrins; D048728:MAP Kinase Kinase Kinase 1; D020928:Mitogen-Activated Protein Kinases; D019869:Phosphatidylinositol 3-Kinases; D017346:Protein Serine-Threonine Kinases; D011505:Protein-Tyrosine Kinases; D011518:Proto-Oncogene Proteins; D051057:Proto-Oncogene Proteins c-akt; D019253:Proto-Oncogene Proteins c-bcl-2; D048051:p38 Mitogen-Activated Protein Kinases; C496050:PTK2 protein, human; C494918:AKT1 protein, human; C482576:MAP3K1 protein, human