RGD Reference Report - Dietary polyunsaturated fats regulate rat liver sterol regulatory element binding proteins-1 and -2 in three distinct stages and by different mechanisms. - Rat Genome Database

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Dietary polyunsaturated fats regulate rat liver sterol regulatory element binding proteins-1 and -2 in three distinct stages and by different mechanisms.

Authors: Xu, J  Cho, H  O'Malley, S  Park, JH  Clarke, SD 
Citation: Xu J, etal., J Nutr. 2002 Nov;132(11):3333-9.
RGD ID: 2308833
Pubmed: PMID:12421847   (View Abstract at PubMed)

Male Sprague-Dawley rats, trained to consume their daily energy needs in a single 3-h meal (0900-1200 h), were used to examine the hypothesis that polyunsaturated fatty acids (PUFA) lowered the nuclear content of sterol regulatory element binding protein (SREBP)-1 and/or -2 by suppressing the proteolytic release of mature SREBP from the membrane-anchored precursor pool. The nuclear concentrations of hepatic SREBP-1 and -2 were 50 and 42% lower (P < 0.05) in rats that consumed a single PUFA-supplemented meal (i.e., 10 g fish oil/100 g fat-free diet) than in rats fed the fat-free diet alone. This was paralleled by 63 and 52% reductions in the expression of the SREBP-1 and -2 target genes, fatty acid synthase and HMG-CoA synthase, respectively; but the marked increase in the amount of precursor SREBP-1 and -2 resulting from meal ingestion was unaffected. After the consumption of a second meal of fish oil, the nuclear level of mature SREBP-1 was only 16% of that in rats fed the fat-free diet, but the amount of nuclear SREBP-2 was not different from the level in rats fed the fat-free diet. Again, the sizes of the SREBP-1 and -2 precursor pools were not reduced. A decrease in the hepatic concentration of precursor SREBP-1 did not occur until rats had consumed 5 meals of fish oil. At this point, the nuclear content of SREBP-2 was actually twofold higher (P < 0.05) in rats fed fish oil or safflower oil, but the amount of precursor SREBP-2 was unaffected. These data indicate that PUFA suppress the in vivo proteolytic release of SREBP-1 and -2, but the effect on SREBP-2 is transitory, possibly reflecting the ability of PUFA to enhance cholesterol losses via bile acid synthesis.



Gene Ontology Annotations    Click to see Annotation Detail View

Biological Process

  
Object SymbolSpeciesTermQualifierEvidenceWithNotesSourceOriginal Reference(s)
Srebf1Ratresponse to lipid  IEP  RGD 

Objects Annotated

Genes (Rattus norvegicus)
Srebf1  (sterol regulatory element binding transcription factor 1)


Additional Information