Hypoxia

Definition: Hypoxia is a deficiency of oxygen, which causes cell injury by reducing aerobic oxidative respiration. Hypoxia is an extremely important and common cause of cell injury and cell death.

Although hypoxia is widely associated with adult pathologies such as cancer, it is also a physiological process that regulates cell differentiation during organogenesis.

Hypoxia and development

Low levels of oxygen (O2) occur naturally in developing embryos. Cells respond to their hypoxic microenvironment by stimulating several hypoxia-inducible factors (and other molecules that mediate O2 homeostasis), which then coordinate the development of the blood, vasculature, placenta, nervous system and other organs.

Furthermore, embryonic stem and progenitor cells frequently occupy hypoxic ’niches’ and low O2 regulates their differentiation.

There is an important link between factors that are involved in regulating stem and progenitor cell behaviour and hypoxia-inducible factors, which provides a molecular framework for the hypoxic control of differentiation and cell fate. (18285802)

See also

 cellular hypoxia
 tissular hypoxia
 systemic hypoxia
 fetal hypoxia
 Ischemia
 HIF1A
 response to hypoxia

References

Simon MC, Keith B. The role of oxygen availability in embryonic development and stem cell function. Nat Rev Mol Cell Biol. 2008 Apr;9(4):285-96. PMID: 18285802

 Sainson RC, Harris AL. Hypoxia-regulated differentiation: let’s step it up a Notch. Trends Mol Med. 2006 Apr;12(4):141-3. PMID: 16513423

 Pugh CW, Ratcliffe PJ. Regulation of angiogenesis by hypoxia: role of the HIF system. Nat Med. 2003 Jun;9(6):677-84. PMID: 12778166

 Michiels C. Physiological and pathological responses to hypoxia. Am J Pathol. 2004 Jun;164(6):1875-82. PMID: 15161623

 Poellinger L, Johnson RS. HIF-1 and hypoxic response: the plot thickens. Curr Opin Genet Dev. 2004 Feb;14(1):81-5. PMID: 15108809

 Li C, Jackson RM: Reactive species mechanisms of cellular hypoxia-reoxygenation injury. Am J Physiol Cell Physiol 282:C227, 2002.