Normal oxygen delivery is essential for survival of metazoan organisms and evo-lutionarily conserved mechanisms have been developed to maintain oxygen homeostasis. Changes in tissue oxygen levels in pathologic conditions are caused by an imbalance between cellular oxygen demand and tissue oxygen delivery. Thus, tissue hypoxia is a hallmark of a number of pathologic conditions ranging from cancer to inflammatory diseases. Oxygen homeostasis is by and large maintained through a family of hypoxia-inducible transcription factors (HIFs), composed of a constitutively expressed HIF-1beta subunit and a HIF-alpha subunit (HIF-1alpha and HIF-2alpha) that is tightly regulated by tissue oxygen levels.
展开▼
