Genome-wide identification of palmitate-regulated immediate early genes and target genes in pancreatic beta-cells reveals a central role of NF-κB.
Free fatty acid-induced pancreatic β-cell dysfunction plays a key role in the pathogenesis of type 2 diabetes. We conducted gene expression microarray analysis to comprehensively investigate the transcription machinery of palmitate-regulated genes in pancreatic β-cells in vitro. In particular, mouse pancreatic βTC3 cells were treated with palmitate in the presence or absence of cycloheximide (CHX), which blocks protein synthesis and thereby allows us to distinguish immediate early genes (IEGs) from their target genes. The microarray experiments identified 34 palmitate-regulated IEGs and 74 palmitate-regulated target genes. In silico promoter analysis revealed that transcription factor binding sites for NF-κB were over-represented, regulating approximately one-third of the palmitate-regulated target genes. In cells treated with CHX, nfkb1 showed an up-regulation by palmitate, suggesting that NF-κB could be an IEG. Functional enrichment analysis of 27 palmitate-regulated genes with NF-κB binding sites showed an over-representation of genes involved in immune response, inflammatory response, defense response, taxis, regulation of cell proliferation, and regulation of cell death pathways. Electrophoretic mobility shift assay showed that palmitate stimulates NF-κB activity both in the presence and absence of CHX. In conclusion, by identifying IEGs and target genes, the present study depicted a comprehensive view of transcription machinery underlying palmitate-induced inflammation and cell proliferation/death in pancreatic β-cells and our data demonstrated the central role of NF-κB.
Department of Internal Medicine, Seoul National University College of Medicine, Seoul, Korea.
Hyung Jin
HJ
Choi
Seungwoo
S
Hwang
Se-Hee
SH
Lee
You Ri
YR
Lee
Jiyon
J
Shin
Kyong Soo
KS
Park
Young Min
YM
Cho
D000818:Animals; D001665:Binding Sites; D002478:Cells, Cultured; D003513:Cycloheximide / Q000494:pharmacology; D020869:Gene Expression Profiling; D005786:Gene Expression Regulation; D053263:Gene Regulatory Networks; D017781:Genes, Immediate-Early; D016678:Genome; D050417:Insulin-Secreting Cells / Q000378:metabolism*; D051379:Mice; D016328:NF-kappa B / Q000502:physiology*; D020411:Oligonucleotide Array Sequence Analysis; D010168:Palmitates / Q000494:pharmacology*; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D014176:Protein Biosynthesis / Q000187:drug effects; D060066:Protein Interaction Maps
D016328:NF-kappa B; D010168:Palmitates; D003513:Cycloheximide