cellular response to oxygen levels

Definition

Target type: biologicalprocess

Any process that results in a change in state or activity of a cell (in terms of movement, secretion, enzyme production, gene expression, etc.) as a result of a stimulus reflecting the presence, absence, or concentration of oxygen. [GOC:mah]

Cellular response to oxygen levels is a fundamental process that allows cells to adapt to fluctuating oxygen availability. Oxygen is essential for aerobic respiration, the primary mechanism for generating ATP, the energy currency of cells. However, oxygen levels can vary significantly in different environments and within different tissues, requiring cells to develop sophisticated mechanisms to maintain their viability and function.

The central regulator of cellular oxygen response is the hypoxia-inducible factor (HIF) pathway. HIF is a transcription factor that activates the expression of genes involved in oxygen homeostasis, including angiogenesis, erythropoiesis, glycolysis, and cell survival.

Under normal oxygen conditions (normoxia), HIF is continuously hydroxylated by prolyl hydroxylases (PHDs), enzymes that require oxygen as a cofactor. Hydroxylation targets HIF for degradation by the proteasome.

When oxygen levels decrease (hypoxia), PHD activity is inhibited, leading to HIF stabilization and accumulation in the nucleus. HIF then binds to hypoxia response elements (HREs) in the promoter regions of target genes, stimulating their transcription.

One of the primary responses to hypoxia is the induction of angiogenesis, the formation of new blood vessels. HIF stimulates the production of vascular endothelial growth factor (VEGF), a potent angiogenic factor, which promotes blood vessel growth and improves oxygen delivery to tissues.

Another key response is the stimulation of erythropoiesis, the production of red blood cells. HIF increases the production of erythropoietin (EPO), a hormone that stimulates the production of red blood cells in the bone marrow, thereby increasing the oxygen-carrying capacity of the blood.

Hypoxia also triggers a metabolic shift towards glycolysis, a less efficient but oxygen-independent pathway for ATP production. HIF promotes the expression of glucose transporters and glycolytic enzymes, allowing cells to generate ATP even in the absence of sufficient oxygen.

Finally, HIF plays a crucial role in cell survival under hypoxic conditions. HIF activates the expression of genes involved in apoptosis inhibition, autophagy, and antioxidant defense, helping cells to cope with the stress of low oxygen availability.

In summary, cellular response to oxygen levels is a complex and multifaceted process that involves a cascade of molecular events, ultimately leading to the adaptation of cells to fluctuating oxygen environments. This response is essential for maintaining cellular homeostasis, promoting tissue survival, and ensuring organismal well-being.'
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Proteins (2)

Compounds (8)