Characterization of bovine pancreatic ductal cells isolated by a perfusion-digestion technique

Summary Bovine pancreatic ductal cells isolated by perfusing an enzyme solution into the lumen of the main duct were obtained as sheets of cells. Morphologic features of these cells were those of pancreatic ductal epithelial cells. These cells also contained alcian blue/periodic acid-Schiff positive material and bound lectins, and they stained for keratin in the same manner as intact ductal epithelium. In culture, the plating efficiency was high (13.6%) as determined by DNA content before and after 24 h plating, perhaps due to the gentle isolation technique and the isolation of sheets of cells rather than a single cell. Cell doubling time was 34.4 h in Eagle's minimal essential medium with 10% heat inactivated fetal bovine serum and antibodies, and over 95% of the cell incorporated [³H]thymidine during a 6 h labeling period after 4 d in primary culture. Isolated cells grew best in medium CMRL 1066 with 10% heat inactivated fetal bovine serum as determined by measuring DNA content. The paper is Publication 1100 from the Department of Pathology, University of Maryland School of Medicine. This study was supported in part by National Cancer Institute (Bethesda, MD) Contract NO1-CP-75947 and Grant CA-19197-06 through the National Pancreatic Cancer Project.     

Rab27a in pancreatic beta-cells, a busy protein in membrane trafficking

The small GTPases have the ‘active’ GTP-bound and ‘inactive’ GDP-bound states, and thereby act as a molecular switch in cells. Rab27a is a member of this family and exists in T-lymphocytes, melanocytes and pancreatic beta-cells. Rab27a regulates secretion of cytolytic granules from cytotoxic T-lymphocytes and intracellular transport of melanosomes in melanocytes. In pancreatic beta-cells, Rab27a controls pre-exocytotic stages of insulin secretion. A few GTP-dependent Rab27a effectors are known to mediate these cellular functions. We recently found that Rab27a also possesses the GDP-dependent effector coronin 3. Coronin 3 regulates endocytosis in pancreatic beta-cells through its interaction with GDP-Rab27a. These results imply that GTP- and GDP-Rab27a actively regulate distinct stages in the insulin secretory pathway. In this review, we provide an overview of the roles of both GTP- and GDP-Rab27a in pancreatic beta-cells.