Gene expression profiles during beta cell maturation and after IL-1? exposure reveal important roles of Pdx-1 and Nkx6.1 for IL-1? sensitivity

Abstract

Aim/hypothesis. Maturation of the beta cells in the islets of Langerhans is dependent upon sequential activation of different transcription factors such as Pdx-1 and Nkx6.1. This maturation is associated with an acquired sensitivity to cytokines and may eventually lead to type 1 diabetes. The aims of this study were to characterise changes in mRNA expression during beta cell maturation as well as after interleukin-1β (IL-1β) exposure. Methods. Transcriptome analyses were performed on two phenotypes characterised as a glucagon-producing pre-beta-cell phenotype (NHI-glu), which matures to an IL-1β-sensitive insulin-producing beta cell phenotype (NHI-ins). Beta cell lines over-expressing Pdx-1 or Nkx6.1, respectively, were used for functional characterisation of acquired IL-1β sensitivity.Results. During beta cell maturation 98 fully annotated mRNAs changed expression levels. Of these, 50 were also changed after 24 h of IL-1β exposure. In addition, 522 and 197 fully annotated mRNAs, not affected by maturation, also changed expression levels following IL-1β exposure of the beta cell and the prebeta-cell phenotype, respectively. Beta cell maturation was associated with an increased expression of Nkx6.1, whereas both Pdx-1 and Nkx6.1 expression were decreased following IL-1β exposure. Over-expression of Nkx6.1 or Pdx-1 in cell lines resulted in a significantly increased sensitivity to IL-1β. Conclusions/interpretation. These results suggest that the final beta cell maturation accompanied by increased IL-1β sensitivity is, in part, dependent upon the expression of genes regulated by Pdx-1 and Nkx6.1. Future classification of the genes regulated by these transcription factors and changed during beta cell maturation should elucidate their role in the acquired sensitivity to IL-1β and may be helpful in identifying new targets for intervention/prevention strategies.

The intrauterine metabolic environment modulates the gene expression pattern in fetal rat islets: prevention by maternal taurine supplementation

“…These changes are smaller than those observed in islets exposed to acute stress, e.g. by cytokines [30] or to high glucose levels [31]. However, significant changes in the expression levels of 10% of islet genes seem sufficient to modify the fetal beta cell phenotype.…”

Transcriptional profiling of type 1 diabetes genes on chromosome 21 in a rat beta-cell line and human pancreatic islets

“…5 Cells were cultured in RPMI 1640 with or without 500 ng/ml doxycycline. After 24 h, IL-1b (40 ng/ml) 6 was added, and cells were harvested at 2, 4, 6, 12 and 24 h, respectively. Insulin and nitric oxide measurements were carried out on media to confirm an effect of the IL-1b exposure.…”

“…Insulin and nitric oxide measurements were carried out on media to confirm an effect of the IL-1b exposure. 6 RNA and array processing were carried out as described in. 5 Interacting proteins with similar expression profile (correlation coefficient40.7) are shown.…”

“…The first approach was based on a rat insulinoma cell line (INS-1ab) overexpressing pancreatic duodenum homeobox 1 (pdx-1). 5,6 Beta-cell maturation is dependent on sequential activation of different transcription factors, including pdx-1, 5 and is accompanied by increased sensitivity to the toxic effects of interleukin 1b (IL-1b). 7 Cytokines have been shown to play a key role in the destruction of beta cells, 8 and we have demonstrated an increased sensitivity to IL-1b in INS-1ab overexpressing pdx-1.…”

“…7 Cytokines have been shown to play a key role in the destruction of beta cells, 8 and we have demonstrated an increased sensitivity to IL-1b in INS-1ab overexpressing pdx-1. 6 Extensive microarray analysis was carried out with these cells treated with IL-1b for different periods of time. In the second approach, human pancreatic islets from eight donors were examined in another array-based evaluation of gene expression of the 33 positional human candidate genes with and without stimulation with a mixture of cytokines, mimicking the presumed pathogenesis of T1D in humans.…”