Activation of mitogen-activated protein kinases in different models of pancreatic acinar cell damage.
Mitogen-activated protein kinase (MAPK) family members, namely MAPK, c-Jun NH2-terminal protein kinase (JNK), and p38MAPK, have been recently reported to have opposing effects on apoptosis.


OBJECTIVE
To determine the activity of MAPKs and the level of Bax, Bcl-2 and p53--proteins known to be involved in the regulation of apoptosis--in pancreatic acini subjected to stressful stimuli leading to cell death.


RESULTS
Isolated pancreatic acini were irradiated for 30 min with ultraviolet B (UV-B) or stimulated with supraphysiological concentrations of cholecystokinin (CCK). As it was assessed by means of acridine orange/ethidium bromide staining, irradiation with UV-B induced predominantly apoptosis while necrosis predominated in CCK-stimulated acini. The activity of MAPK, JNK and p38MAPK was determined by means of Western-blotting, with the use of antibodies which recognize active, dually phosphorylated enzymes. Irradiation with UV-B induced a rapid, 3-fold increase in MAPK activity. It had a maximum at 30 min and then gradually declined to reach the normal level at 120 min. Concomitantly, early activation of p38-MAPK was found at 30 min. However, unlike MAPK, p38-MAPK activity was then gradually rising to reach a maximum (5-fold increase) at 180 min. UV-B-induced activation of both kinases was not affected by the pretreatment with antioxidant--N-acetylo-L-cysteine or protein kinase C inhibitor--GF-109203X. In UV-B-irradiated cells, we did not detect any significant JNK activation as well as any significant changes in Bax, Bcl-2 and p53 levels assessed by means of Western-blotting.


CONCLUSIONS
It seems likely that a specific interaction between MAPK and p38MAPK signaling pathway may be involved in the determination of the cell death mechanism in pancreatic acini subjected to stressful stimuli.
Dabrowski
A
A
Department of Gastroenterology, Medical School of Bialystok, Poland. adabrows@amb.ac.bialystok.pl
Tribillo
I
I
Dabrowska
M I
MI
Wereszczynska-Siemiatkowska
U
U
Gabryelewicz
A
A
D000818:Animals; D017209:Apoptosis / Q000187:drug effects / Q000502:physiology* / Q000528:radiation effects; D016923:Cell Death / Q000187:drug effects / Q000502:physiology / Q000528:radiation effects; D002766:Cholecystokinin / Q000494:pharmacology; D004789:Enzyme Activation / Q000187:drug effects / Q000528:radiation effects; D020935:MAP Kinase Signaling System / Q000187:drug effects / Q000502:physiology* / Q000528:radiation effects; D008297:Male; D010179:Pancreas / Q000166:cytology* / Q000187:drug effects / Q000528:radiation effects; D011518:Proto-Oncogene Proteins / Q000502:physiology; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000502:physiology; D051381:Rats; D017208:Rats, Wistar; D016159:Tumor Suppressor Protein p53 / Q000502:physiology; D014466:Ultraviolet Rays; D051028:bcl-2-Associated X Protein
C494828:Bax protein, rat; D011518:Proto-Oncogene Proteins; D019253:Proto-Oncogene Proteins c-bcl-2; D016159:Tumor Suppressor Protein p53; D051028:bcl-2-Associated X Protein; D002766:Cholecystokinin