Article

Diabetologia

, Volume 50, Issue 5, pp 1006-1014

Global profiling of genes modified by endoplasmic reticulum stress in pancreatic beta cells reveals the early degradation of insulin mRNAs

  • P. PirotAffiliated withLaboratory of Experimental Medicine, Université Libre de Bruxelles (ULB)
  • , N. NaamaneAffiliated withLaboratory of Experimental Medicine, Université Libre de Bruxelles (ULB)
  • , F. LibertAffiliated withInstitute of Interdisciplinary Research (IRIBHM), Université Libre de Bruxelles (ULB)
  • , N. E. MagnussonAffiliated withMolecular Diagnostic Laboratory, Department of Clinical Biochemistry, Aarhus University Hospital
  • , T. F. ØrntoftAffiliated withMolecular Diagnostic Laboratory, Department of Clinical Biochemistry, Aarhus University Hospital
  • , A. K. CardozoAffiliated withLaboratory of Experimental Medicine, Université Libre de Bruxelles (ULB)
  • , D. L. EizirikAffiliated withLaboratory of Experimental Medicine, Université Libre de Bruxelles (ULB) Email author 

Abstract

Aims/hypothesis

Pancreatic beta cells respond to endoplasmic reticulum (ER) stress by activating the unfolded protein response. If the stress is prolonged, or the adaptive response fails, apoptosis is triggered. We used a ‘homemade’ microarray specifically designed for the study of beta cell apoptosis (the APOCHIP) to uncover mechanisms regulating beta cell responses to ER stress.

Materials and methods

A time course viability and microarray analysis was performed in insulin-producing INS-1E cells exposed to the reversible ER stress inducer cyclopiazonic acid (CPA). Modification of selected genes was confirmed by real-time RT-PCR, and the observed inhibition of expression of the insulin-1 (Ins1) and insulin-2 (Ins2) genes was further characterised in primary beta cells exposed to a diverse range of agents that induce ER stress.

Results

CPA-induced ER stress modified the expression of 183 genes at one or more of the time points studied. The expression of most of these genes returned to control levels after a 3 h recovery period following CPA removal, with all cells surviving. Two groups of genes were particularly affected by CPA, namely, those related to cellular responses to ER stress, which were mostly upregulated, and those related to differentiated beta cell functions, which were downregulated. Levels of Ins1 and Ins2 mRNAs were severely decreased in response to CPA treatment as a result of degradation, and there was a concomitant increase in the level of IRE1 activation.

Conclusions/interpretation

In this study we provide the first global analysis of beta cell molecular responses to a severe ER stress, and identify the early degradation of mRNA transcripts of the insulin genes as an important component of this response.

Keywords

Apoptosis CPA Cyclopiazonic acid Diabetes mellitus Endoplasmic reticulum stress Insulin Interleukin-1 Pancreatic beta cells