Pancreas Vol. 7, No. 5 , pp. 556-561 0 1992 Raven Press, Ltd., New York

Carbonic Anhydrase I1 Gene Expression in Mouse Pancreatic Duct Cells Sherwood Githens, Jane A. Schexnayder, and *Marsha L. Frazier Department of Biological Sciences, University of New Orleans, New Orleans, Louisiana, and *Section of Gastrointestinal Oncology and Digestive Diseases, University of Texas M.D. Anderson Cancer Center, Houston, Texas, U.S.A.

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Summary: Our goal is to create a transgenic mouse model for human pancreatic duct cell adenocarcinoma using the promoterlenhancer region of the carbonic anhydrase (CA) I1 gene to drive the expression of SV-40 T-antigen in pancreatic duct cells. This requires that the CA I1 gene be expressed in mouse pancreatic duct cells and not in other pancreatic cells, as has already been shown to be the case in the human and guinea pig pancreas. We have shown with an enzyme histochemical assay that mouse pancreatic duct cells contain CA activity in both intact pancreas and cultured interlobular duct epithelium. In addition, CA activity was detected with a biochemical assay in homogenates of cultured duct epithelium. The specific activity of duct cells was 2.75-fold greater than in whole pancreas, suggesting that a substantial amount of total pancreatic CA activity is contributed by duct cells. At least some of the CA in cultured duct cells was inferred to be CA I1 by Northern blot analysis of RNA extracted from the cells. The concentration of CA 11 mRNA in the cultured duct cells was substantially greater than in whole pancreas and would appear to account for the majority, if not all, of the CA I1 in the mouse pancreas. Key Words: Carbonic anhydrase-Duct-Epithelial cell culture-Pancreas.

current evidence indicates that the CA I1 isozyme is produced in pancreatic duct cells, but not in islet or acinar cells (4). In a recent immunohistochemical study on CA I1 gene expression, CA I1 was detected in the colon but not in the pancreas of the mouse, while the ducts of the guinea pig pancreas were intensely positive for CA I1 ( 5 ) . Because the mouse is often used as a model for molecular studies on the pancreas and because we are interested in developing a transgenic mouse model for human pancreatic duct cell adenocarcinoma, we wanted to verify these findings using different methodologies. In the present study, we used biochemical, enzyme histochemical, and Northern blot analyses to demonstrate that CA activity and CA I1 mRNA are produced by mouse pancreatic duct cells.

Carbonic anhydrases (CAs) are zinc-containing metalloenzymes that are products of a multigene family. In pancreatic duct cells, CA catalyzes the hydration of carbon dioxide, thus providing bicarbonate anions required for the elaboration of the bicarbonate-rich solution secreted by the duct epithelium (1,2). The pancreatic duct epithelium comprises

Carbonic anhydrase II gene expression in mouse pancreatic duct cells.

Our goal is to create a transgenic mouse model for human pancreatic duct cell adenocarcinoma using the promoter/enhancer region of the carbonic anhydr...
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