Extracellular ATP activates MAP kinase cascades through a P2Y purinergic receptor in the human intestinal Caco-2 cell line.
BACKGROUND
ATP exerts diverse effects on various cell types via specific purinergic P2Y receptors. Intracellular signaling cascades are the main routes of communication between P2Y receptors and regulatory targets in the cell.


RESULTS
We examined the role of ATP in the modulation of ERK1/2, JNK1/2, and p38 MAP kinases (MAPKs) in human colon cancer Caco-2 cells. Immunoblot analysis showed that ATP induces the phosphorylation of MAPKs in a time- and dose-dependent manner, peaking at 5 min at 10 microM ATP. Moreover, ATPgammaS, UTP, and UDP but not ADP or ADPbetaS increased phosphorylation of MAPKs, indicating the involvement of, at least, P2Y2/P2Y4 and P2Y6 receptor subtypes. RT-PCR studies and PCR product sequencing supported the expression of P2Y2 and P2Y4 receptors in this cell line. Spectrofluorimetric measurements showed that cell stimulation with ATP induced transient elevations in intracellular calcium concentration. In addition, ATP-induced phosphorylation of MAPKs in Caco-2 cells was dependent on Src family tyrosine kinases, calcium influx, and intracellular Ca2+ release and was partially dependent on the cAMP/PKA and PKC pathways and the EGFR.


CONCLUSIONS
These findings provide new molecular basis for further understanding the mechanisms involved in ATP functions, as a signal transducer and activator of MAP kinase cascades, in colon adenocarcinoma Caco-2 cells.
Buzzi
Natalia
N
Departamento de Biología, Bioquímica y Farmacia, Universidad Nacional del Sur, San Juan 670, 8000 Bahía Blanca, Argentina.
Bilbao
Paola Scodelaro
PS
Boland
Ricardo
R
de Boland
Ana Russo
AR
D000255:Adenosine Triphosphate / Q000378:metabolism / Q000494:pharmacology*; D018938:Caco-2 Cells; D045744:Cell Line, Tumor; D020895:Enterocytes / Q000187:drug effects / Q000378:metabolism; D004789:Enzyme Activation / Q000187:drug effects; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005110:Extracellular Space / Q000378:metabolism; D006801:Humans; D007413:Intestinal Mucosa / Q000378:metabolism; D007422:Intestines / Q000187:drug effects*; D048031:JNK Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism; D020935:MAP Kinase Signaling System / Q000187:drug effects*; D048052:Mitogen-Activated Protein Kinase 3 / Q000037:antagonists & inhibitors / Q000378:metabolism; D010766:Phosphorylation / Q000187:drug effects; D018048:Receptors, Purinergic P2 / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D013997:Time Factors; D048051:p38 Mitogen-Activated Protein Kinases / Q000378:metabolism
D004791:Enzyme Inhibitors; D018048:Receptors, Purinergic P2; D000255:Adenosine Triphosphate; D048031:JNK Mitogen-Activated Protein Kinases; D048052:Mitogen-Activated Protein Kinase 3; D048051:p38 Mitogen-Activated Protein Kinases