Signaling mechanisms of glucagon-like peptide 2-induced intestinal epithelial cell proliferation.
BACKGROUND
Glucagon-like peptide 2 (GLP-2) stimulates intestinal epithelial growth with high potency and specificity. However, the intracellular signaling pathways responsible for the growth-stimulatory action of GLP-2 are not clearly understood. Here we report possible signaling pathways mediating GLP-2's proliferative actions in the human intestinal epithelial cell line Caco-2.


METHODS
Caco-2 cells were subcultured under serum-deprived conditions in the presence or absence of GLP-2 (10 microM) and varying concentrations of inhibitors of three candidate kinases: genistein, a global tyrosine kinase inhibitor; LY294002, a phosphatidylinositide (PI) 3-kinase inhibitor; and PD 098059, a mitogen-activated/extracellular signal-regulated kinase (MEK) inhibitor. Proliferation was assessed using [(3)H]thymidine incorporation. Relative abundance of the phosphorylated forms of two specific mitogen-activated protein kinases (MAPKs), ERK1 and ERK2, was assessed by Western blotting.


RESULTS
GLP-2-treated cells demonstrated a greater than 10-fold increase in proliferation. This response was inhibited by genistein, LY294002, and PD 098059 in a dose-dependent fashion. A significantly greater abundance of the phosphorylated forms of both ERK-1 and ERK-2 was present in cells within 5 min of treatment with GLP-2.


CONCLUSIONS
GLP-2 stimulates the proliferation of Caco-2 cells in vitro. This increase in Caco-2 proliferation in response to GLP-2 may be due, at least in part, to the involvement of both the PI 3-kinase and the MAPK pathways.
Jasleen
J
J
Department of Surgery, Brigham and Women's Hospital, Boston, Massachusetts 02115, USA.
Shimoda
N
N
Shen
E R
ER
Tavakkolizadeh
A
A
Whang
E E
EE
Jacobs
D O
DO
Zinner
M J
MJ
Ashley
S W
SW
D018938:Caco-2 Cells; D002455:Cell Division / Q000187:drug effects; D004247:DNA / Q000096:biosynthesis; D053767:Glucagon-Like Peptide 2; D004763:Glucagon-Like Peptides; D006801:Humans; D007413:Intestinal Mucosa / Q000166:cytology / Q000187:drug effects*; D019950:Mitogen-Activated Protein Kinase 1 / Q000502:physiology; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases / Q000502:physiology; D010455:Peptides / Q000494:pharmacology*; D019869:Phosphatidylinositol 3-Kinases / Q000502:physiology; D015398:Signal Transduction
D053767:Glucagon-Like Peptide 2; D010455:Peptides; D004763:Glucagon-Like Peptides; D004247:DNA; D019869:Phosphatidylinositol 3-Kinases; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases