Lack of oxygen’s epigenetic effects

This 2016 Finnish review’s subject was the epigenetic effects of hypoxia:

“Ever since the Cambrian period, oxygen availability has been in the center of energy metabolism. Hypoxia stabilizes the expression of hypoxia-inducible transcription factor-1α (HIF-1α), which controls the expression of hundreds of survival genes related to enhanced energy metabolism and autophagy.

There are several other signals, mostly related to stresses, which can increase the expression of HIF factors and thus improve cellular survival. However, a chronic activation of HIF factors can have detrimental effects, e.g. stimulate cellular senescence and tissue fibrosis commonly enhanced in age-related diseases.

Stabilization of HIF-1α increases the expression of histone lysine demethylases (KDM). Hypoxia-inducible KDMs support locally the gene transcription induced by HIF-1α, although they can also control genome-wide chromatin landscape, especially KDMs which demethylate H3K9 and H3K27 sites (repressive epigenetic marks).”

Gene areas where HIF-1α is involved include:

  • “angiogenesis
  • autophagy
  • glucose uptake
  • glycolytic enzymes
  • immune responses
  • embryonic development
  • tumorigenesis
  • generation of miRNAs.”

Figure 1 was instructive in that the reviewers pointed out the lack of a feedback mechanism in HIF-1α signaling. A natural lack of feedback to the HIF-1α signaling source contributed to diseases such as:

  • “age-related macular degeneration
  • cancer progression
  • chronic kidney disease
  • cardiomyopathies
  • adipose tissue fibrosis
  • inflammation
  • detrimental effects which are linked to epigenetic changes.”

The point was similar to a study referenced in The PRice “equation” for individually evolving: Which equation describes your life? that:

“Evolution may preferentially mitigate damage to a biological system than reduce the source of this damage.”


The review was complicated primarily because the subject has many interdependencies and timings within a complex network. Contexts are important:

“The cross-talk between NF-κB [nuclear factor kappa B] and HIF-1α in inflammation might be organized in cell type and context-dependent manner.

It seems that ROS [reactive oxygen species] affect the HIF-1α signaling in a context-dependent manner.

Hypoxia stimulated the expression of KDM3A and KDM4B genes in different cellular contexts. Given that KDM3A and KDM4B are the major histone demethylases which remove the repressive H3K9 sites, their role as transcriptional cofactors seems to be important in the activation of HIF-1α signaling..members of KDM4 subfamily have a crucial role in the DNA repair systems, although the responses seem to be enzyme-specific and appear in a context-dependent manner.

Acute hypoxia can stimulate cell-cycle arrest but does not provoke cellular senescence in all contexts.”

It wasn’t mentioned that hypoxia evokes cellular Adaptations to stress encourage mutations in a DNA area that causes diseases.

The review was tailored for the publishing journal Aging and Disease, and the subject was best summed up by:

“HIF-1α can control cellular fate in adult animals, either stimulating proliferation or triggering cellular senescence, by regulating the expression of different KDMs in a context-dependent manner.”


The review covered hypoxic conditions during human development that are clearly the origins of many immediate and later-life diseases. However, the cited remedies only addressed symptoms.

That these distant causes can no longer be addressed is a hidden assumption of research and treatment of effects of health problems. Aren’t such assumptions testable here in 2016?

http://www.aginganddisease.org/article/2016/2152-5250/147502 “Hypoxia-Inducible Histone Lysine Demethylases: Impact on the Aging Process and Age-Related Diseases”

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