title: Identification of an intracellular metabolic signature impairing beta cell function in the rat beta cell line INS-1E and human islets.
abstract: OBJECTIVE
  Chronic hyperglycaemia promotes the progressive failure of pancreatic beta cells in patients with type 2 diabetes mellitus, a clinically highly relevant phenomenon known as glucotoxicity. The intracellular metabolic consequences of a chronically high availability of glucose in beta cells are, as yet, poorly understood in its full complexity.
  
  
  METHODS
  An unbiased metabolite profiling analysis (GC-time-of-flight-MS) was used to identify the time course of core metabolite patterns in rat beta cell line INS-1E during exposure to high glucose concentrations and its relation to insulin expression.
  
  
  RESULTS
  We report here that pentose phosphate pathway (PPP) metabolites accumulate remarkably during chronic but not acute glucose treatment, indicating altered processing of glucose through the pentose phosphate pathway. Subsequent functional studies in INS-1E cells and human islets revealed that a disturbance in this pathway contributes to decreases in insulin gene expression and a lack of glucose-stimulated insulin secretion. These effects were found to depend on the activation of extracellular-regulated-kinase (ERK1/2). Long-term inhibition of 6-phosphogluconic acid dehydrogenase resulted in accumulation of PPP metabolites, induced ERK1/2 activation independently of high glucose and impaired beta cell function. In turn, inhibition of ERK1/2 overstimulation during chronic glucose exposure partly inhibited metabolite accumulation and restored beta cell function.
  
  
  CONCLUSIONS
  Based on unbiased metabolite analyses, the data presented here provide novel targets, namely the inhibition of PPP metabolite accumulation towards the therapeutic goal to preserve and potentially improve beta cell function in diabetes.
authors.affiliation: Department of Endocrinology, Diabetes and Nutrition, Charité-Universitaetsmedizin Berlin, Nuthetal, Germany.
authors.forename: I
authors.initials: I
authors.lastname: Goehring
authors.forename: N S
authors.initials: NS
authors.lastname: Sauter
authors.forename: G
authors.initials: G
authors.lastname: Catchpole
authors.forename: A
authors.initials: A
authors.lastname: Assmann
authors.forename: L
authors.initials: L
authors.lastname: Shu
authors.forename: K S
authors.initials: KS
authors.lastname: Zien
authors.forename: M
authors.initials: M
authors.lastname: Moehlig
authors.forename: A F H
authors.initials: AF
authors.lastname: Pfeiffer
authors.forename: J
authors.initials: J
authors.lastname: Oberholzer
authors.forename: L
authors.initials: L
authors.lastname: Willmitzer
authors.forename: J
authors.initials: J
authors.lastname: Spranger
authors.forename: K
authors.initials: K
authors.lastname: Maedler
mesh_terms: D000818:Animals; D015153:Blotting, Western; D002460:Cell Line; D003924:Diabetes Mellitus, Type 2 / Q000378:metabolism; D015870:Gene Expression / Q000187:drug effects; D005947:Glucose / Q000494:pharmacology; D006801:Humans; D050417:Insulin-Secreting Cells / Q000187:drug effects / Q000378:metabolism* / Q000502:physiology; D007515:Islets of Langerhans / Q000187:drug effects / Q000378:metabolism* / Q000503:physiopathology*; D013058:Mass Spectrometry; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3 / Q000378:metabolism; D010427:Pentose Phosphate Pathway / Q000502:physiology; D010734:Phosphogluconate Dehydrogenase / Q000378:metabolism; D051381:Rats
chemical_list: D010734:Phosphogluconate Dehydrogenase; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D005947:Glucose