title: Pseudoislet formation enhances gene expression, insulin secretion and cytoprotective mechanisms of clonal human insulin-secreting 1.1B4 cells.
abstract: We have studied the effects of cell communication on human beta cell function and resistance to cytotoxicity using the novel human insulin-secreting cell line 1.1B4 configured as monolayers and pseudoislets. Incubation with the incretin gut hormones GLP-1 and GIP caused dose-dependent stimulation of insulin secretion from 1.1B4 cell monolayers and pseudoislets. The secretory responses were 1.5-2.7-fold greater than monolayers. Cell viability (MTT), DNA damage (comet assay) and apoptosis (acridine orange/ethidium bromide staining) were investigated following 2-h exposure of 1.1B4 monolayers and pseudoislets to ninhydrin, H2O2, streptozotocin, glucose, palmitate or cocktails of proinflammatory cytokines. All agents tested decreased viability and increased DNA damage and apoptosis in both 1.1B4 monolayers and pseudoislets. However, pseudoislets exhibited significantly greater resistance to cytotoxicity (1.5-2.7-fold increases in LD50) and lower levels of DNA damage (1.3-3.4-fold differences in percentage tail DNA and olive tail moment) and apoptosis (1.3-1.5-fold difference) compared to monolayers. Measurement of gene expression by reverse-transcription, real-time PCR showed that genes involved with insulin secretion (INS, PDX1, PCSK1, PCSK2, GLP1R and GIPR), cell-cell communication (GJD2, GJA1 and CDH1) and antioxidant defence (SOD1, SOD2, GPX1 and CAT) were significantly upregulated in pseudoislets compared to monolayers, whilst the expression of proapoptotic genes (NOS2, MAPK8, MAPK10 and NFKB1) showed no significant differences. In summary, these data indicate cell-communication associated with three-dimensional islet architecture is important both for effective insulin secretion and for protection of human beta cells against cytotoxicity.
authors.affiliation: SAAD Centre for Pharmacy and Diabetes, University of Ulster, Cromore Road, Coleraine, BT52 1SA, Northern Ireland, UK.
authors.forename: Alastair D
authors.initials: AD
authors.lastname: Green
authors.affiliation: SAAD Centre for Pharmacy and Diabetes, University of Ulster, Cromore Road, Coleraine, BT52 1SA, Northern Ireland, UK. s.vasu@ulster.ac.uk.
authors.forename: Srividya
authors.initials: S
authors.lastname: Vasu
authors.affiliation: SAAD Centre for Pharmacy and Diabetes, University of Ulster, Cromore Road, Coleraine, BT52 1SA, Northern Ireland, UK.
authors.forename: Neville H
authors.initials: NH
authors.lastname: McClenaghan
authors.affiliation: SAAD Centre for Pharmacy and Diabetes, University of Ulster, Cromore Road, Coleraine, BT52 1SA, Northern Ireland, UK.
authors.forename: Peter R
authors.initials: PR
authors.lastname: Flatt
mesh_terms: D017209:Apoptosis; D002450:Cell Communication; D002460:Cell Line; D016207:Cytokines / Q000494:pharmacology; D004249:DNA Damage; D006801:Humans; D054795:Incretins / Q000494:pharmacology; D007328:Insulin / Q000378:metabolism*; D050417:Insulin-Secreting Cells / Q000187:drug effects / Q000378:metabolism*; D018384:Oxidative Stress; D055571:Secretory Pathway
chemical_list: D016207:Cytokines; D054795:Incretins; D007328:Insulin
keywords: 1.1B4 cells; Beta cell; Cell communication; Cytotoxicity; Insulin secretion