Induction of early response genes in trypsin inhibitor-induced pancreatic growth

Abstract

Endogenous CCK release induced by a synthetic trypsin inhibitor, camostat, stimulates pancreatic growth; however, the mechanisms mediating this growth are not well established. Early response genes often couple short-term signals with long-term responses. To study their participation in the pancreatic growth response, mice were fasted for 18 h and refed chow containing 0.1% camostat for 1–24 h. Expression of 18 early response genes were evaluated by quantitative PCR; mRNA for 17 of the 18 increased at 1, 2, 4, or 8 h. Protein expression for c-jun, c-fos, ATF-3, Egr-1, and JunB peaked at 2 h. Nuclear localization was confirmed by immunohistochemistry of c-fos, c-jun, and Egr-1. Refeeding regular chow induced only a small increase of c-jun and none in c-fos expression. JNKs and ERKs were activated 1 h after camostat feeding as was the phosphorylation of c-jun and ATF-2. AP-1 DNA binding evaluated by EMSA showed a significant increase 1–2 h after camostat feeding with participation of c-jun, c-fos, ATF-2, ATF-3, and JunB shown by supershift. The CCK antagonist IQM-95,333 blocked camostat feeding-induced c-jun and c-fos expression by 67 and 84%, respectively, and AP-1 DNA binding was also inhibited. In CCK-deficient mice, the maximal response of c-jun induction and AP-1 DNA binding were reduced by 64 and 70%, respectively. These results indicate that camostat feeding induces a spectrum of early response gene expression and AP-1 DNA binding and that these effects are mainly CCK dependent.

Profiling CCK-mediated pancreatic growth: the dynamic genetic program and the role of STATs as potential regulators

“…Cryostat sections (6 m thick) of snapfrozen pancreas were picked up on glass slides and fixed for 10 min in 100% methanol at Ϫ20°C. Immunofluorescence localization was performed following methods described previously (8). Rabbit monoclonal anti-P-STAT3 (#D3A7) antibody from Cell Signaling was diluted 1:800; secondary antibody was Alexa 594 diluted 1:200.…”

“…Work on CCK-driven pancreatic growth in vivo has thus far focused on the following three pathways: mitogen-activated protein kinases ERKs and JNKs (8), nutritional sensors AKT and mammalian target of rapamycin (mTOR) (3), as well as the calcineurin-nuclear factor of activated T-cells (CN/NFAT) cascade (41). First, elevated CCK-induced by administration of protease inhibitor (PI)-containing chow has been shown to activate ERK, JNK, and their downstream mediators, including activated protein-1 (AP-1) (8).…”

“…First, elevated CCK-induced by administration of protease inhibitor (PI)-containing chow has been shown to activate ERK, JNK, and their downstream mediators, including activated protein-1 (AP-1) (8). Second, CCK also activates the atypical kinase mTOR, which leads to phosphorylation of initiation factor 4E binding protein and protein S6 kinase, as well as resultant increase in protein synthesis (1).…”

Update Lecture: Benign Diseases of the Exocrine Pancreas

“…Furthermore, CCK and other hormones are involved in the regulation of protein synthesis, regeneration, and growth of the exocrine pancreas. Some genes involved in these processes respond rather early after CCK stimulation of the acinar cells [4]. …”

“…I may refer to the numerous outstanding scientific contributions in this field by my former mentor, John A. Williams, Ann Arbor, Mich., USA [e.g. [1,2,3,4]]. However, the main focus of this review will be on presentation of some new aspects of pathophysiology, diagnosis, and conservative treatment of both acute and chronic pancreatitis.…”