Mechanisms by which diet and other endogenous factors modify the microsomal membrane fatty acid composition, structure, physical properties and membrane bound protein function

BRENNER, R.R.

Advances in Lipid Metabolism

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Lugar: Kerala, India; Año: 2007;

            The fatty acid (FA) composition and dynamics of the hepatic microsomal membrane may be altered by the diet or factors that modify the activity of enzymes like the ∆9, ∆6 and ∆5 desaturases that modulate the unsaturated FA biosynthesis. The effects of diets, diabetes and several nuclear receptors have been compared, determining the hepatic microsomal lipidic composition, mRNA and activity of the microsomal desaturases and the dynamic properties measured at different depths of the membrane. The mentioned factors modify the unsaturated fatty acid composition and the molecular species distribution, but in different ways and with different effects. Dietary EFA deficiency and 1% cholesterol administration similarly depress 20:4n-6 but increase 16:1 and 18:1n-9 by different mechanisms. Diabetes type 1 due to insulin absence, differently decreased both monoenoic fatty acids and 20:4n-6/18:2 ratio due to a depression of both SCD-1 and ∆6 and ∆5 desaturases. Insulin corrected these effects in a similar way to the in vivo activation of LXR, PPAR-á and SREBP-1c by increasing  mRNAs and activities of SCD-1 and ∆6 and ∆5 desaturases. All these factors altered the density of double bonds at different depths of the membrane and specifically the dynamic properties.