Intercellular contacts affect secretion and biosynthesis of pancreatic islet cells.

Cell protein biosynthesis is regulated by different factors, but implication of intercellular contacts on alpha and beta cell protein biosyntheses activity has not been yet investigated. Islet cell biosynthetic activity is essential in regulating not only the hormonal reserve within cells but also in renewing all the proteins involved in the control of secretion. Here we aimed to assess whether intercellular interactions affected similarly secretion and protein biosynthesis of rat alpha and beta cells.

Cadherin engagement improves insulin secretion of single human β-cells.

The aim of this study was to assess whether cadherin-mediated adhesion of human islet cells was affected by insulin secretagogues and explore the role of cadherins in the secretory activity of β-cells. Experiments were carried out with single islet cells adherent to chimeric proteins made of functional E-, N-, or P-cadherin ectodomains fused to the Fc fragment of immunoglobulin (E-cad/Fc, N-cad/Fc, and P-cad/Fc) and immobilized on an inert substrate. We observed that cadherin expression in islet cells was not affected by insulin secretagogues.

Expression and secretion of alpha1-proteinase inhibitor are regulated by proinflammatory cytokines in human pancreatic islet cells.

Aims/hypothesis: Alpha1-proteinase inhibitor (alpha1-PI) has been considered a key player in inflammatory processes. In humans, the main production site of alpha1-PI is the liver, but other tissues, including pancreatic islets, also synthesise this molecule. The aims of this study were to assess the islet cell types that produce alpha1-PI, to determine whether alpha1-PI is actually secreted by islet cells, and to assess how its production and/or secretion are regulated.

Optimization of neutral protease to collagenase activity ratio for islet of Langerhans isolation.

Aim: The optimal neutral protease to collagenase activity ratio has not been determined for islet isolation. We evaluated a new highly purified collagenase that can be blended with predetermined amounts of neutral protease (NP).

Methods: Islets were isolated from 7 groups of Sprague-Dawley rats.