Differences in aggregation properties and levels of the neural cell adhesion molecule (NCAM) between islet cell types

Exp Cell Res. 1990 Dec;191(2):305-12. doi: 10.1016/0014-4827(90)90019-7.

Abstract

Cells within rat islets of Langerhans are typically organized as a core of B-cells, surrounded by the other cell types. When mixed in culture, primary islet cells and insulinoma (RIN2A) cells form aggregates where B-cells are centrally located, surrounded by non-B-cells, while RIN-cells segregate as the outermost layer. To gain insight into the molecular basis underlying this nonrandom cellular organization, the aggregation properties of the three cell populations were studied. Isolated islet cells were separated into B-cells and non-B-cells by autofluorescence-activated cell sorting (FACS). In a short-term aggregation assay, primary B-cell aggregation in the absence of calcium was only 19 +/- 3.7%, compared to the 67 +/- 2.9% seen in the presence of calcium (mean +/- SEM; P less than 0.001; n = 7). By contrast, non-B-cell aggregation and RIN cell aggregation in the absence of calcium (62 +/- 2 and 66 +/- 2%, respectively) were only slightly less than with calcium (70 +/- 3 and 76 +/- 3%). The surface density of the Ca2(+)-independent neural CAM (NCAM) was therefore measured by flow cytometry and found to be 2.64 +/- 0.82-fold higher in non-B-cells, compared to that in B-cells (P less than 0.01; n = 3). Even higher levels were found on RIN cells. In the three cell types, NCAM-140 was the only molecular form detected by immunoblotting. In conclusion, differences in the calcium dependency of aggregation and in the levels of NCAM are demonstrated among islet B-cells, non-B-cells, and RIN cells. Because cell-cell adhesion is crucial for the maintenance of adult tissue, these aggregation specificities might contribute to the concentric segregation of islet cell types in culture and to the nonrandom distribution of cells within rat islets.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Calcium / pharmacology
  • Cell Adhesion Molecules, Neuronal / analysis
  • Cell Adhesion Molecules, Neuronal / genetics
  • Cell Adhesion Molecules, Neuronal / metabolism*
  • Cell Aggregation / drug effects
  • Cell Aggregation / physiology
  • Cell Line
  • Cell Separation
  • Flow Cytometry
  • Gene Expression / drug effects
  • Immunoblotting
  • Insulinoma / chemistry
  • Insulinoma / metabolism
  • Insulinoma / pathology
  • Islets of Langerhans / chemistry
  • Islets of Langerhans / cytology*
  • Islets of Langerhans / metabolism
  • Pancreatic Neoplasms / chemistry
  • Pancreatic Neoplasms / metabolism
  • Pancreatic Neoplasms / pathology
  • Rats
  • Rats, Inbred Strains

Substances

  • Cell Adhesion Molecules, Neuronal
  • Calcium