The HIF (hypoxia-inducible factor) family of oxygen-sensing proteins are a crucial element of cells’ responses to alterations in their immediate environment, kicking off a signaling cascade involving more than 1000 genes. HypOxystation users Taylor and See at the University of Liverpool describe novel insights into the subcellular localization of some of the HIF proteins and why the “where” determines the “how”.

HIF-2α and HIF-1α both form heterodimers with HIF-1β, and while similarities abound between the isoforms, the two subunits are differentially expressed and regulated and have distinctly separate target genes. Taylor and See triggered HIF activation using microscope stage incubators and the Hypoxystation by Don Whitley Scientific to incubate HeLa cells in hypoxia (1%). They found that while HIF-1α distributes homogenously in the nucleus, HIF-2α diffuses freely through the nucleus but is concentrated in speckles that are tethered to nuclear structures close to active RNA polymerases. This distribution is not significantly altered by low oxygen levels.

The Hypoxystation provides physiologically relevant, in vivo conditions for cell culture and manipulation to ensure authentic behavior of cells. User-defined parameters for temperature, CO2, O2 and humidity, plus the workstation format, where cells reside throughout the entire duration of the assays, minimize the extra-physiologic shock that is known to negatively impact metabolism and growth. As the degree and duration of hypoxia are among the factors controlling HIF activity, the customizable oxygen atmosphere inside the HypOxystation can contribute to deciphering the functionality of oxygen-sensitive signaling pathways.

It was previously found that the DNA sequence of HRE elements in genes controlled by HIF-2α does not differ from those controlled by HIF-1α, even though target genes generally exhibit a preference either for HIF-2α or HIF-1α. Taylor and See demonstrated that sequestering HIF-2α in specific sites such as speckles, perhaps in conjunction with other transcription factors, may serve to regulate movement of this transcription factor and thus, potentially, its availability for transcription of specific genes. The speckles scrutinized by Taylor and See offer a novel model for how access and mobility can differentially regulate gene expression in response to the microenvironment.

Click here to view Dr. See on using the HypOxystation: ”We are very happy with it, because it is reliable and we get an excellent support service.”