Docosahexaenoic acid (DHA) and hepatic gene transcription

Chem Phys Lipids. 2008 May;153(1):3-13. doi: 10.1016/j.chemphyslip.2008.02.007. Epub 2008 Feb 23.

Abstract

The type and quantity of dietary fat ingested contributes to the onset and progression of chronic diseases, like diabetes and atherosclerosis. The liver plays a central role in whole body lipid metabolism and responds rapidly to changes in dietary fat composition. Polyunsaturated fatty acids (PUFA) play a key role in membrane composition and function, metabolism and the control of gene expression. Certain PUFA, like the n-3 PUFA, enhance hepatic fatty acid oxidation and inhibit fatty acid synthesis and VLDL secretion, in part, by regulating gene expression. Our studies have established that key transcription factors, like PPARalpha, SREBP-1, ChREBP and MLX, are regulated by n-3 PUFA, which in turn control levels of proteins involved in lipid and carbohydrate metabolism. Of the n-3 PUFA, 22:6,n-3 has recently been established as a key controller of hepatic lipid synthesis. 22:6,n-3 controls the 26S proteasomal degradation of the nuclear form of SREBP-1. SREBP-1 is a major transcription factor that controls the expression of multiple genes involved fatty acid synthesis and desaturation. 22:6,n-3 suppresses nuclear SREBP-1, which in turn suppresses lipogenesis. This mechanism is achieved, in part, through control of the phosphorylation status of protein kinases. This review will examine both the general features of PUFA-regulated hepatic gene transcription and highlight the unique mechanisms by which 22:6,n-3 impacts gene expression. The outcome of this analysis will reveal that changes in hepatic 22:6,n-3 content has a major impact on hepatic lipid and carbohydrate metabolism. Moreover, the mechanisms involve 22:6,n-3 control of several well-known signaling pathways, such as Akt, Erk1/2, Gsk3beta and PKC (novel or atypical). 22:6,n-3 control of these same signaling pathways in non-hepatic tissues may help to explain the diverse actions of n-3 PUFA on such complex physiological processes as visual acuity and learning.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, U.S. Gov't, Non-P.H.S.
  • Review

MeSH terms

  • Animals
  • Docosahexaenoic Acids / metabolism*
  • Gene Expression Regulation*
  • Glycolysis
  • Humans
  • Lipid Metabolism*
  • Lipogenesis
  • Liver / metabolism*
  • Signal Transduction
  • Transcription Factors / metabolism*
  • Transcription, Genetic*

Substances

  • Transcription Factors
  • Docosahexaenoic Acids