Serum lipoprotein-derived fatty acids regulate hypoxia-inducible factor.

Area of Science:

• Biochemistry
• Molecular Biology
• Cell Biology

Background:

• Oxygen is a key regulator of hypoxia-inducible factors (HIF), influencing critical cellular processes like metabolism and angiogenesis.
• The role of lipids, specifically fatty acids, in modulating HIF activity remains largely unknown.

Purpose of the Study:

• To investigate whether lipids, particularly lipoprotein-derived fatty acids, act as independent regulators of HIF activity.
• To elucidate the mechanism by which fatty acids influence HIF signaling and its downstream effects.

Main Methods:

• Experiments were conducted using cultured cells and two animal models (zebrafish and mice).
• Assays included measuring HIF prolyl hydroxylation, HIFα subunit accumulation, and downstream target gene expression.
• Studies involved manipulating extracellular lipid supply and supplementing with fatty acids.

Main Results:

• Lipoprotein-derived fatty acids were identified as an independent regulator of HIF.
• Reduced lipid supply inhibited HIF prolyl hydroxylation, leading to HIFα accumulation and target gene activation, mimicking hypoxia.
• Fatty acid addition suppressed this signaling, dependent on an intact mitochondrial respiratory chain.
• This lipid-HIF signaling pathway was observed in developing zebrafish, adult mice, and various cancer cell types.

Conclusions:

• Fatty acids represent a novel physiological modulator of HIF activity, distinct from oxygen.
• This pathway provides a mechanism for lipoprotein regulation of HIF, operating in parallel to oxygen sensing.
• The findings have implications for understanding cell metabolism, angiogenesis, and cancer biology.