Identification and Characterization of α3β1 Integrin on Primary and Transformed Rat Islet Cells

Dispersed rat islet cells embedded in a matrix of collagen I are known to form aggregatesin vitroreminiscent of native islets. Furthermore, it appears that islet function and survival are better maintainedin vitrowhen cells are grown in the presence of extracellular matrix. These studies suggest an important role of cell–matrix interactions in the formation and maintenance of islet structure and function. The molecular basis of these interactions is mostly unknown. In the present study, we confirm the presence of β1 integrins on primary and transformed (RIN-2A line) rat islet cells. Perturbation studiesin vitroshow that β1 integrins play a role in islet cell attachment and spreading on bovine extracellular matrix and on the matrix produced by A-431 cells. The α3 integrin subunit is coimmunoprecipitated with β1 from extracts of both primary and transformed islet cells, and immunodepletion studies suggest that α3β1 represents nearly half of the total β1 integrins expressed on primary islet cells.In situ,α3 and β1 are expressed on the surface of all islet cell types, as shown by indirect immunocytochemistry on paraformaldehyde-fixed sections of rat pancreas. In conclusion, the study demonstrates the presence of α3β1 on primary and transformed rat islet cells, and an important role of β1 integrins in islet cell attachment and spreadingin vitro.