Cell-to-cell contact influences proliferative marker expression and apoptosis in MIN6 cells grown in islet-like structures.
Cell-to-cell interactions play an important role in the development and maintenance of the beta-cell phenotype. Here, we have investigated whether E-cadherin plays a role in regulating the growth of insulin-secreting MIN6 cells configured as three-dimensional islet-like clusters (pseudoislets). Pseudoislets form by cell aggregation rather than by proliferation from individual cells and attain the size of primary mouse islets after approximately 7 days of maintenance in culture. E-cadherin is known to mediate homotypic cell adhesion between beta-cells and has also been implicated in a number of cellular processes, including proliferation, apoptosis, and differentiation. E-cadherin and its associated intracellular elements, alpha- and beta-catenin, were upregulated in MIN6 pseudoislets. Pseudoislet formation was associated with an increased expression of cyclin-dependent kinase inhibitors and a concomitant downregulation of Ki67, suggesting an overall reduction in cellular proliferation. However, measurements of 5-bromo-2'-deoxyuridine incorporation revealed that there were no differences in the rate of MIN6 cell proliferation whether they were configured as monolayers or as pseudoislets, which is likely to be a result of their being a transformed cell line. Cells within pseudoislets were not necrotic, but apoptosis appeared to be upregulated in the islet-like structures. However, no differential expression of Fas and FasL was detected in monolayers and pseudoislets. These results suggest that cell-to-cell interactions within islet-like structures may initiate antiproliferative and proapoptotic signals.
Beta-Cell Development and Function Group, Division of Reproductive Health, Endocrinology and Development, Hodgkin Bldg., King's College London, Guy's Campus, London Bridge, London SE1 1UL, UK.
Melanie J
MJ
Luther
Emma
E
Davies
Dany
D
Muller
Moira
M
Harrison
Adrian J
AJ
Bone
Shanta J
SJ
Persaud
Peter M
PM
Jones
D000818:Animals; D017209:Apoptosis / Q000502:physiology*; D015415:Biomarkers / Q000378:metabolism*; D015153:Blotting, Western; D001973:Bromodeoxyuridine / Q000378:metabolism; D015820:Cadherins / Q000378:metabolism; D002449:Cell Aggregation / Q000502:physiology; D002450:Cell Communication / Q000502:physiology*; D018797:Cell Cycle Proteins / Q000378:metabolism; D045744:Cell Line, Tumor; D049109:Cell Proliferation; D050759:Cyclin-Dependent Kinase Inhibitor p21; D050760:Cyclin-Dependent Kinase Inhibitor p27; D003598:Cytoskeletal Proteins / Q000378:metabolism; D004247:DNA / Q000096:biosynthesis; D053222:Fas Ligand Protein; D006651:Histocytochemistry; D020287:In Situ Nick-End Labeling; D007515:Islets of Langerhans / Q000166:cytology / Q000378:metabolism / Q000502:physiology*; D019394:Ki-67 Antigen / Q000378:metabolism; D008562:Membrane Glycoproteins / Q000378:metabolism; D051379:Mice; D015534:Trans-Activators / Q000378:metabolism; D025521:Tumor Suppressor Proteins / Q000378:metabolism; D051178:alpha Catenin; D051176:beta Catenin; D001616:beta-Galactosidase / Q000032:analysis; D019014:fas Receptor / Q000378:metabolism
D015415:Biomarkers; C495267:CTNNB1 protein, mouse; D015820:Cadherins; C493957:Cdkn1a protein, mouse; C493961:Cdkn1b protein, mouse; D018797:Cell Cycle Proteins; C495272:Ctnna1 protein, mouse; D050759:Cyclin-Dependent Kinase Inhibitor p21; D003598:Cytoskeletal Proteins; D053222:Fas Ligand Protein; C505658:Fasl protein, mouse; D019394:Ki-67 Antigen; D008562:Membrane Glycoproteins; D015534:Trans-Activators; D025521:Tumor Suppressor Proteins; D051178:alpha Catenin; D051176:beta Catenin; D019014:fas Receptor; D050760:Cyclin-Dependent Kinase Inhibitor p27; D004247:DNA; D001616:beta-Galactosidase; D001973:Bromodeoxyuridine