Optical analysis of cellular oxygen sensing.

Molecular imaging of the assembly of hypoxia inducible factor (HIF) complexes in living cells may lead to a deeper understanding of cellular oxygen sensing. Sophisticated live cell imaging has extended the toolbox to study the molecular response to changes in oxygen supply. In this respect fluorescence resonance energy transfer (FRET) as a technique to investigate protein-protein interaction in the nanoscale range gets increasing interest. Herein, we review FRET studies related to hypoxia research, emphasizing on recent progress, but also demonstrating how FRET studies are complementary or potentially superior to conventional biochemical as well as histochemical techniques. Technical advances in the application of FRET in living cells will overcome restrictions to end-point analysis on the population rather than single cell level and will thereby provide progress in understanding the cellular hypoxic response by HIF.