title: Differential expression of E-cadherin at the surface of rat beta-cells as a marker of functional heterogeneity.
abstract: The aim of this study was to assess whether the expression of E-cadherin at the surface of rat beta-cells is regulated by insulin secretagogues and correlates with insulin secretion. When cultured under standard conditions, virtually all beta-cells expressed E-cadherin observed by immunofluorescence, but heterogeneous staining was observed. Using fluorescence-activated cell sorting (FACS), two beta-cell sub-populations were sorted: one that was poorly labeled ('ECad-low') and another that was highly labeled ('ECad-high'). After 1-h stimulation with 16.7 mM glucose, insulin secretion (reverse hemolytic plaque assay) from individual ECad-high beta-cells was higher than that from ECad-low beta-cells. Ca2+-dependent beta-cell aggregation was increased at 16.7 mM glucose when compared with 2.8 mM glucose. E-cadherin at the surface of beta-cells was increased after 18 h at 11.1 and 22.2 mM glucose when compared with 2.8 mM glucose, with the greatest increase at 22.2 mM glucose + 0.5 mM isobutylmethylxanthine (IBMX). While no labeling was detected on freshly trypsinized cells, the proportion of stained cells increased in a time-dependent manner during culture for 1, 3, and 24 h. This recovery was faster when cells were incubated at 16.7 vs 2.8 mM glucose. Cycloheximide inhibited expression of E-cadherin at 2.8 mM glucose, but not at 16.7 mM, while depolymerization of actin by either cytochalasin B or latrunculin B increased surface E-cadherin at low glucose. In conclusion, these results show that expression of E-cadherin at the surface of islet beta-cells is controlled by secretagogues including glucose, correlates with insulin secretion, and can serve as a surface marker of beta-cell function.
authors.affiliation: Surgical Research Unit, Department of Surgery, Cell Isolation and Transplantation Center, CMU, Geneva University Hospitals, 1, rue Michel-Servet, 1211 Geneva-4, Switzerland. domenico.bosco@medecine.unige.ch
authors.forename: Domenico
authors.initials: D
authors.lastname: Bosco
authors.forename: Dominique G
authors.initials: DG
authors.lastname: Rouiller
authors.forename: Philippe A
authors.initials: PA
authors.lastname: Halban
mesh_terms: D015056:1-Methyl-3-isobutylxanthine / Q000494:pharmacology; D000199:Actins / Q000378:metabolism; D000818:Animals; D015415:Biomarkers / Q000032:analysis; D019086:Bridged Bicyclo Compounds, Heterocyclic / Q000494:pharmacology; D015820:Cadherins / Q000032:analysis / Q000378:metabolism*; D002478:Cells, Cultured; D003513:Cycloheximide / Q000494:pharmacology; D003571:Cytochalasin B / Q000494:pharmacology; D003603:Cytotoxins / Q000494:pharmacology; D005434:Flow Cytometry; D005455:Fluorescent Antibody Technique; D005947:Glucose / Q000378:metabolism / Q000494:pharmacology; D007328:Insulin / Q000378:metabolism*; D000078790:Insulin Secretion; D007515:Islets of Langerhans / Q000737:chemistry / Q000378:metabolism*; D008297:Male; D008387:Marine Toxins / Q000494:pharmacology; D010726:Phosphodiesterase Inhibitors / Q000494:pharmacology; D011500:Protein Synthesis Inhibitors / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D053778:Thiazolidines / Q000494:pharmacology; D013997:Time Factors
chemical_list: D000199:Actins; D015415:Biomarkers; D019086:Bridged Bicyclo Compounds, Heterocyclic; D015820:Cadherins; D003603:Cytotoxins; D007328:Insulin; D008387:Marine Toxins; D010726:Phosphodiesterase Inhibitors; D011500:Protein Synthesis Inhibitors; D053778:Thiazolidines; D003571:Cytochalasin B; D003513:Cycloheximide; D005947:Glucose; C037068:latrunculin B; D015056:1-Methyl-3-isobutylxanthine