Limits...
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.

Show MeSH

Related in: MedlinePlus

Transcriptional induction according to real-time PCR analysis.Real-time PCR analysis was performed analysing mRNA levels of the 9 genes differentially regulated after 3, 6 and 16 hours treatment under hypoxic conditions (1% O2). Results of 4–6 independent experiments each performed in triplicate are expressed as mean values ± SE. Values are depicted relative to the untreated control. *** p<0.001; ** p<0.01; * p<0.05.
© Copyright Policy
Related In: Results  -  Collection


getmorefigures.php?uid=PMC3198480&req=5

pone-0026465-g005: Transcriptional induction according to real-time PCR analysis.Real-time PCR analysis was performed analysing mRNA levels of the 9 genes differentially regulated after 3, 6 and 16 hours treatment under hypoxic conditions (1% O2). Results of 4–6 independent experiments each performed in triplicate are expressed as mean values ± SE. Values are depicted relative to the untreated control. *** p<0.001; ** p<0.01; * p<0.05.

Mentions: To prove the validity of the microarray data, the set of the 9 significantly regulated genes after all investigated time periods (3, 6, 16 h) under hypoxia was also determined by real-time PCR. These validation experiments were equally performed for all time periods used in the microarray analysis and were assessed by repeated experiments (figure 5). Overall, the regulation patterns measured in the real-time PCR experiments reflected the results of the microarray data, with one exception: In the case of WDR73 of the validation experiments a significant regulation of gene expression in the opposite direction was observed compared to the microarray data. Given the verified transcriptional upregulation of ADM, ANKRD37, DDIT4, KDM3A, PFKFB4, PPP1R3C, VEGFA and ZNF395 on the one hand and their clustering in response to hypoxia according to gene ontology, we were interested in a potentially coordinated expression. Reinvestigating the 514 genes upregulated after 16 h, we noticed that HIF2A is on the one hand a transcription factor, binding to upregulated genes as diplayed in figure 3 and 4, and, on the other hand, upregulated itself in SBGS adipocytes after 16h of hypoxia. According to our binding site analysis, HIF1, HIF2A and TFAP4 together bind all eight genes which were verified by real time PCR to be upregulated under hypoxia (figure 4) and therefore might be sufficient to induce their activation.


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)

Transcriptional induction according to real-time PCR analysis.Real-time PCR analysis was performed analysing mRNA levels of the 9 genes differentially regulated after 3, 6 and 16 hours treatment under hypoxic conditions (1% O2). Results of 4–6 independent experiments each performed in triplicate are expressed as mean values ± SE. Values are depicted relative to the untreated control. *** p<0.001; ** p<0.01; * p<0.05.
© Copyright Policy
Related In: Results  -  Collection

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

pone-0026465-g005: Transcriptional induction according to real-time PCR analysis.Real-time PCR analysis was performed analysing mRNA levels of the 9 genes differentially regulated after 3, 6 and 16 hours treatment under hypoxic conditions (1% O2). Results of 4–6 independent experiments each performed in triplicate are expressed as mean values ± SE. Values are depicted relative to the untreated control. *** p<0.001; ** p<0.01; * p<0.05.
Mentions: To prove the validity of the microarray data, the set of the 9 significantly regulated genes after all investigated time periods (3, 6, 16 h) under hypoxia was also determined by real-time PCR. These validation experiments were equally performed for all time periods used in the microarray analysis and were assessed by repeated experiments (figure 5). Overall, the regulation patterns measured in the real-time PCR experiments reflected the results of the microarray data, with one exception: In the case of WDR73 of the validation experiments a significant regulation of gene expression in the opposite direction was observed compared to the microarray data. Given the verified transcriptional upregulation of ADM, ANKRD37, DDIT4, KDM3A, PFKFB4, PPP1R3C, VEGFA and ZNF395 on the one hand and their clustering in response to hypoxia according to gene ontology, we were interested in a potentially coordinated expression. Reinvestigating the 514 genes upregulated after 16 h, we noticed that HIF2A is on the one hand a transcription factor, binding to upregulated genes as diplayed in figure 3 and 4, and, on the other hand, upregulated itself in SBGS adipocytes after 16h of hypoxia. According to our binding site analysis, HIF1, HIF2A and TFAP4 together bind all eight genes which were verified by real time PCR to be upregulated under hypoxia (figure 4) and therefore might be sufficient to induce their activation.

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