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Identification of hypoxia-induced genes in human SGBS adipocytes by microarray analysis.

Geiger K, Leiherer A, Muendlein A, Stark N, Geller-Rhomberg S, Saely CH, Wabitsch M, Fraunberger P, Drexel H - PLoS ONE (2011)

Bottom Line: Therefore, we compared gene expression profiles of human Simpson-Golabi-Behmel syndrome (SGBS) adipocytes under normoxic or hypoxic conditions to detect hypoxia-responsive genes in adipocytes by using whole human genome microarrays.Moreover in six of these eight genes we identified HIF response elements in the proximal promoters, specific for the HIF transcription factor family members HIF1A and HIF2A.In addition, the identified hypoxia-regulated genes are likely involved in the regulation of obesity, the incidence of type 2 diabetes, and the metabolic syndrome.

View Article: PubMed Central - PubMed

Affiliation: Vorarlberg Institute for Vascular Investigation and Treatment, Feldkirch, Austria.

ABSTRACT
Hypoxia in adipose tissue is suggested to be involved in the development of a chronic mild inflammation, which in obesity can further lead to insulin resistance. The effect of hypoxia on gene expression in adipocytes appears to play a central role in this inflammatory response observed in obesity. However, the global impact of hypoxia on transcriptional changes in human adipocytes is unclear. Therefore, we compared gene expression profiles of human Simpson-Golabi-Behmel syndrome (SGBS) adipocytes under normoxic or hypoxic conditions to detect hypoxia-responsive genes in adipocytes by using whole human genome microarrays. Microarray analysis showed more than 500 significantly differentially regulated mRNAs after incubation of the cells under low oxygen levels. To gain further insight into the biological processes, hypoxia-regulated genes after 16 hours of hypoxia were classified according to their function. We identified an enrichment of genes involved in important biological processes such as glycolysis, response to hypoxia, regulation of cellular component movement, response to nutrient levels, regulation of cell migration, and transcription regulator activity. Real-time PCR confirmed eight genes to be consistently upregulated in response to 3, 6 and 16 hours of hypoxia. For adipocytes the hypoxia-induced regulation of these genes is shown here for the first time. Moreover in six of these eight genes we identified HIF response elements in the proximal promoters, specific for the HIF transcription factor family members HIF1A and HIF2A. In the present study, we demonstrated that hypoxia has an extensive effect on gene expression of SGBS adipocytes. In addition, the identified hypoxia-regulated genes are likely involved in the regulation of obesity, the incidence of type 2 diabetes, and the metabolic syndrome.

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Binding sites for transcription factors within promoter regions.(A) Tabulated view of all matched matrix sequences for transcription factors (TF) as displayed in figure 3. Hits for transcription factors which were generated according to different matrices representing the same transcription factor were summed up. (B) Schematic representation of matched binding sites for transcription factors (arrows) within proximal promoters of the eight verified hypoxia-induced genes and WDR73. Overlapping binding sites of different matrices which represent the same transcription factor (family) are indicated as single site in the figure. Binding sites of the unknown factor were omitted.
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pone-0026465-g004: Binding sites for transcription factors within promoter regions.(A) Tabulated view of all matched matrix sequences for transcription factors (TF) as displayed in figure 3. Hits for transcription factors which were generated according to different matrices representing the same transcription factor were summed up. (B) Schematic representation of matched binding sites for transcription factors (arrows) within proximal promoters of the eight verified hypoxia-induced genes and WDR73. Overlapping binding sites of different matrices which represent the same transcription factor (family) are indicated as single site in the figure. Binding sites of the unknown factor were omitted.

Mentions: We identified at least one binding site for the human hypoxia-inducible factor 1 alpha subunit (HIF1A) and the endothelial PAS domain protein 1 (EPAS1), also known as HIF2A, a transcriptional activator that acts in cell proliferation, cell migration, hemopoiesis and angiogenesis [32]–[34], sharing the consensus sequence 5′-ACGTG-3′ in ANKRD37, DDIT4, KDM3A, PPP1R3C, PFKFB4 and VEGFA (figure 4 A). Interestingly, several PWMs for the forkhead transcription factor superfamily and one specific for forkhead box O4 (FOXO4), which mediates HIF1A and VEGF downregulation [35] were also recognized. In case of ANKRD37, DDIT4 and PPP1R3C binding sites of FOX- and HIF-family transcription factors overlap (figure 4 B). Apart from that, binding sites for TCF12 and the repressors HES1 and MDS1 are located within the mentioned promoters. We also identified PWMs for transcription factor activating enhancer binding protein 2 (TFAP2A), which is known to activate ADM expression in monocytic leukemia cells [36], for TFAP4 and for transcriptional activators of the GATA binding protein family (figure 3 and 4).


Identification of hypoxia-induced genes in human SGBS adipocytes by microarray analysis.

Geiger K, Leiherer A, Muendlein A, Stark N, Geller-Rhomberg S, Saely CH, Wabitsch M, Fraunberger P, Drexel H - PLoS ONE (2011)

Binding sites for transcription factors within promoter regions.(A) Tabulated view of all matched matrix sequences for transcription factors (TF) as displayed in figure 3. Hits for transcription factors which were generated according to different matrices representing the same transcription factor were summed up. (B) Schematic representation of matched binding sites for transcription factors (arrows) within proximal promoters of the eight verified hypoxia-induced genes and WDR73. Overlapping binding sites of different matrices which represent the same transcription factor (family) are indicated as single site in the figure. Binding sites of the unknown factor were omitted.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3198480&req=5

pone-0026465-g004: Binding sites for transcription factors within promoter regions.(A) Tabulated view of all matched matrix sequences for transcription factors (TF) as displayed in figure 3. Hits for transcription factors which were generated according to different matrices representing the same transcription factor were summed up. (B) Schematic representation of matched binding sites for transcription factors (arrows) within proximal promoters of the eight verified hypoxia-induced genes and WDR73. Overlapping binding sites of different matrices which represent the same transcription factor (family) are indicated as single site in the figure. Binding sites of the unknown factor were omitted.
Mentions: We identified at least one binding site for the human hypoxia-inducible factor 1 alpha subunit (HIF1A) and the endothelial PAS domain protein 1 (EPAS1), also known as HIF2A, a transcriptional activator that acts in cell proliferation, cell migration, hemopoiesis and angiogenesis [32]–[34], sharing the consensus sequence 5′-ACGTG-3′ in ANKRD37, DDIT4, KDM3A, PPP1R3C, PFKFB4 and VEGFA (figure 4 A). Interestingly, several PWMs for the forkhead transcription factor superfamily and one specific for forkhead box O4 (FOXO4), which mediates HIF1A and VEGF downregulation [35] were also recognized. In case of ANKRD37, DDIT4 and PPP1R3C binding sites of FOX- and HIF-family transcription factors overlap (figure 4 B). Apart from that, binding sites for TCF12 and the repressors HES1 and MDS1 are located within the mentioned promoters. We also identified PWMs for transcription factor activating enhancer binding protein 2 (TFAP2A), which is known to activate ADM expression in monocytic leukemia cells [36], for TFAP4 and for transcriptional activators of the GATA binding protein family (figure 3 and 4).

Bottom Line: Therefore, we compared gene expression profiles of human Simpson-Golabi-Behmel syndrome (SGBS) adipocytes under normoxic or hypoxic conditions to detect hypoxia-responsive genes in adipocytes by using whole human genome microarrays.Moreover in six of these eight genes we identified HIF response elements in the proximal promoters, specific for the HIF transcription factor family members HIF1A and HIF2A.In addition, the identified hypoxia-regulated genes are likely involved in the regulation of obesity, the incidence of type 2 diabetes, and the metabolic syndrome.

View Article: PubMed Central - PubMed

Affiliation: Vorarlberg Institute for Vascular Investigation and Treatment, Feldkirch, Austria.

ABSTRACT
Hypoxia in adipose tissue is suggested to be involved in the development of a chronic mild inflammation, which in obesity can further lead to insulin resistance. The effect of hypoxia on gene expression in adipocytes appears to play a central role in this inflammatory response observed in obesity. However, the global impact of hypoxia on transcriptional changes in human adipocytes is unclear. Therefore, we compared gene expression profiles of human Simpson-Golabi-Behmel syndrome (SGBS) adipocytes under normoxic or hypoxic conditions to detect hypoxia-responsive genes in adipocytes by using whole human genome microarrays. Microarray analysis showed more than 500 significantly differentially regulated mRNAs after incubation of the cells under low oxygen levels. To gain further insight into the biological processes, hypoxia-regulated genes after 16 hours of hypoxia were classified according to their function. We identified an enrichment of genes involved in important biological processes such as glycolysis, response to hypoxia, regulation of cellular component movement, response to nutrient levels, regulation of cell migration, and transcription regulator activity. Real-time PCR confirmed eight genes to be consistently upregulated in response to 3, 6 and 16 hours of hypoxia. For adipocytes the hypoxia-induced regulation of these genes is shown here for the first time. Moreover in six of these eight genes we identified HIF response elements in the proximal promoters, specific for the HIF transcription factor family members HIF1A and HIF2A. In the present study, we demonstrated that hypoxia has an extensive effect on gene expression of SGBS adipocytes. In addition, the identified hypoxia-regulated genes are likely involved in the regulation of obesity, the incidence of type 2 diabetes, and the metabolic syndrome.

Show MeSH
Related in: MedlinePlus