HeLa response to hypoxia

Oxygen is vital for the development and survival of mammals. In response to hypoxia, the brain initiates numerous adaptive responses at the organ level as well as at the molecular and cellular level, including the alteration of gene expression. Astrocytes play critical roles in the proper functioning of the brain, thus the manner in which astrocytes respond to hypoxia is likely important in determining the outcome of brain hypoxia. We used microarray gene expression profiling and data analysis algorithms to identify and analyze hypoxia-responsive genes in primary human astrocytes. We also compared the gene expression patterns in astrocytes with those in human HeLa cells and pulmonary artery endothelial cells (ECs). Remarkably, in astrocytes, 5 times as many genes were up-regulated as down-regulated, whereas in HeLa and pulmonary ECs, as many or more genes were down-regulated as up-regulated. More genes encoding hypoxia-inducible functions, such as glycolytic enzymes and angiogenic growth factors, were strongly induced in astrocytes compared to HeLa cells. The extent of induction was also greater than in HeLa cells. Further, gene ontology and computational algorithms revealed that many target genes of the EGF and insulin signaling pathways and the transcriptional regulators Myc, Jun and p53 were selectively altered by hypoxia in astrocytes and HeLa cells to a varying degree. These results provide a global view of the signaling and regulatory network mediating oxygen regulation in astrocytes, in comparison with that in HeLa cells. Keywords: response to hypoxia Gene expression profiles of three independent batches of HeLa cells grown under normoxia were compared to gene expression profiles of three independent batches of HeLa cells grown under 1% oxygen for 24 hours. Affymetrix U133 plus 2.0 microarrays were used.