Cluster analysis of rat pancreatic islet gene mRNA levels after culture in low-, intermediate- and high-glucose concentrations.
OBJECTIVE
Survival and function of insulin-secreting pancreatic beta cells are markedly altered by changes in nutrient availability. In vitro, culture in 10 rather than 2 mmol/l glucose improves rodent beta cell survival and function, whereas glucose concentrations above 10 mmol/l are deleterious.


METHODS
To identify the mechanisms of such beta cell plasticity, we tested the effects of 18 h culture at 2, 5, 10 and 30 mmol/l glucose on the transcriptome of rat islets pre-cultured for 1 week at 10 mmol/l glucose using Affymetrix Rat 230 2.0 arrays.


RESULTS
Culture in either 2-5 or 30 mmol/l instead of 10 mmol/l glucose markedly impaired beta cell function, while little affecting cell survival. Of about 16,000 probe-sets reliably detected in islets, some 5,000 were significantly up- or downregulated at least 1.4-fold by glucose. Analysis of these probe-sets with GeneCluster software identified ten mRNA profiles with unidirectional up- or downregulation between 2 and 10, 2 and 30, 5 and 10, 5 and 30 or 10 and 30 mmol/l glucose. It also identified eight complex V-shaped or inverse V-shaped profiles with a nadir or peak level of expression in 5 or 10 mmol/l glucose. Analysis of genes belonging to these various clusters using Onto-express and GenMAPP software revealed several signalling and metabolic pathways that may contribute to induction of beta cell dysfunction and apoptosis after culture in low- or high- vs intermediate-glucose concentration.


CONCLUSIONS
We have identified 18 distinct mRNA profiles of glucose-induced changes in islet gene mRNA levels that should help understand the mechanisms by which glucose affects beta cell survival and function under states of chronic hypo- or hyperglycaemia.
Bensellam
M
M
Unit of Endocrinology and Metabolism, Faculty of Medicine, Université catholique de Louvain, Avenue Hippocrate 55 (UCL5530), 1200, Brussels, Belgium.
Van Lommel
L
L
Overbergh
L
L
Schuit
F C
FC
Jonas
J C
JC
D000818:Animals; D018929:Cell Culture Techniques; D002470:Cell Survival; D016000:Cluster Analysis; D020869:Gene Expression Profiling; D005934:Glucagon / Q000235:genetics; D005947:Glucose / Q000494:pharmacology*; D007328:Insulin / Q000235:genetics; D007515:Islets of Langerhans / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D007700:Kinetics; D008297:Male; D009693:Nucleic Acid Hybridization; D012333:RNA, Messenger / Q000235:genetics*; D051381:Rats; D017208:Rats, Wistar
D007328:Insulin; D012333:RNA, Messenger; D005934:Glucagon; D005947:Glucose