title: Type 2 diabetes susceptibility gene expression in normal or diabetic sorted human alpha and beta cells: correlations with age or BMI of islet donors.
abstract: BACKGROUND
  Genome-wide association studies have identified susceptibility genes for development of type 2 diabetes. We aimed to examine whether a subset of these (comprising FTO, IDE, KCNJ11, PPARG and TCF7L2) were transcriptionally restricted to or enriched in human beta cells by sorting islet cells into alpha and beta - specific fractions. We also aimed to correlate expression of these transcripts in both alpha and beta cell types with phenotypic traits of the islet donors and to compare diabetic and non-diabetic cells.
  
  
  RESULTS
  Islet cells were sorted using a previously published method and RNA was extracted, reverse transcribed and used as the template for quantitative PCR. Sorted cells were also analysed for insulin and glucagon immunostaining and insulin secretion from the beta cells as well as insulin, glucagon and GLP-1 content. All five genes were expressed in both alpha and beta cells, with significant enrichment of KCNJ11 in the beta cells and of TCF7L2 in the alpha cells. The ratio of KCNJ11 in beta to alpha cells was negatively correlated with BMI, while KCNJ11 expression in alpha cells was negatively correlated with age but not associated with BMI. Beta cell expression of glucagon, TCF7L2 and IDE was increased in cells from islets that had spent more time in culture prior to cell sorting. In beta cells, KCNJ11, FTO and insulin were positively correlated with each other. Diabetic alpha and beta cells had decreased expression of insulin, glucagon and FTO.
  
  
  CONCLUSIONS
  This study has identified novel patterns of expression of type 2 diabetes susceptibility genes within sorted islet cells and suggested interactions of gene expression with age or BMI of the islet donors. However, expression of these genes in islets is less associated with BMI than has been found for other tissues.
authors.affiliation: Department of Cell Physiology and Metabolism, University of Geneva, Geneva, Switzerland.
authors.forename: Clare L
authors.initials: CL
authors.lastname: Kirkpatrick
authors.forename: Piero
authors.initials: P
authors.lastname: Marchetti
authors.forename: Francesco
authors.initials: F
authors.lastname: Purrello
authors.forename: Salvatore
authors.initials: S
authors.lastname: Piro
authors.forename: Marco
authors.initials: M
authors.lastname: Bugliani
authors.forename: Domenico
authors.initials: D
authors.lastname: Bosco
authors.forename: Eelco J P
authors.initials: EJ
authors.lastname: de Koning
authors.forename: Marten A
authors.initials: MA
authors.lastname: Engelse
authors.forename: Julie
authors.initials: J
authors.lastname: Kerr-Conte
authors.forename: François
authors.initials: F
authors.lastname: Pattou
authors.forename: Claes B
authors.initials: CB
authors.lastname: Wollheim
mesh_terms: D001483:Base Sequence; D015992:Body Mass Index; D016022:Case-Control Studies; D017931:DNA Primers; D003924:Diabetes Mellitus, Type 2 / Q000235:genetics* / Q000473:pathology / Q000601:surgery; D020022:Genetic Predisposition to Disease; D055106:Genome-Wide Association Study; D006801:Humans; D016381:Islets of Langerhans Transplantation; D016133:Polymerase Chain Reaction; D014019:Tissue Donors
chemical_list: D017931:DNA Primers