PAP, a pancreatic secretory protein induced during acute pancreatitis, is expressed in rat intestine.

The pancreatitis-associated protein (PAP) is a lectin-related secretory protein present in small amounts in the rat pancreas and rapidly overexpressed during the acute phase of pancreatitis. We demonstrate in this report that PAP is also expressed in rat intestine. A cDNA library from rat jejunum was probed with pancreatic PAP cDNA. The inserts of the selected recombinant clones corresponded to a transcript whose nucleotide sequence was identical to that of pancreatic PAP mRNA. The transcript was detected in duodenum, jejunum, ileum, and colon. A protein with same molecular mass (16 kDa) and pI (8.2) as pancreatic PAP was actually immunodetected in ileum homogenate after separation by two-dimensional sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Intestinal PAP was immunolocalized to the epithelial cells of the lower part of the villi. The protein accounted respectively for 0.02, 0.05, and 0.1% of soluble proteins in duodenum, jejunum, and ileum homogenates, as measured by enzyme-linked immunosorbent assay, and could not be detected in stomach and colon. Influence of fasting and feeding on PAP mRNA concentration was analyzed in ileum. Concentration decreased by 81 and 94% after animals were fasted for 24 and 48 h, respectively. Feeding restored the initial content within 6 h. On the other hand, intestinal PAP mRNA concentration was not altered during acute pancreatitis.