title: A low fish oil inhibits SREBP-1 proteolytic cascade, while a high-fish-oil feeding decreases SREBP-1 mRNA in mice liver: relationship to anti-obesity.
abstract: Rodents fed fish oil showed less obesity with a reduction of triglyceride synthesis in liver, relative to other dietary oils, along with a decrease of mature form of sterol regulatory element binding protein-1 (SREBP-1) and activation of peroxisome proliferator-activated receptor alpha (PPARalpha). Decrease of mature SREBP-1 protein by fish oil feeding was due to either inhibition of SREBP-1 proteolytic cascade or to decrease of its mRNA. To clarify its mechanism and relation to antiobesity effect, mice were fed fish oil in a range from 10 to 60 energy percent (en%). Fish oil feeding decreased body weight and fat mass in a dose-dependent manner, in parallel with PPARalpha activation and a decrease of SREBP-1 mRNA. However, compared with 0 en% fish oil feeding, 10 en% fish oil feeding decreased mature SREBP-1 protein by 50% with concomitant decreases of lipogenic genes, while precursor SREBP-1 protein rather increased by 1.3-fold. These data suggest that physiological doses of fish oil feeding effectively decrease expression of liver lipogenic enzymes by inhibiting SREBP-1 proteolytic cascade, while substantial decrease of SREBP-1 expression is observed in its pharmacological doses, and that activation of PPARalpha rather than SREBP-1 decrease might be related to the antiobesity effect of fish oil feeding.
authors.affiliation: Division of Clinical Nutrition, National Institute of Health and Nutrition, 1-23-1 Toyama, Shinjuku-ku, Tokyo 162-8636, Japan.
authors.forename: Teruyo
authors.initials: T
authors.lastname: Nakatani
authors.forename: Hyoun-Ju
authors.initials: HJ
authors.lastname: Kim
authors.forename: Yasushi
authors.initials: Y
authors.lastname: Kaburagi
authors.forename: Kazuki
authors.initials: K
authors.lastname: Yasuda
authors.forename: Osamu
authors.initials: O
authors.lastname: Ezaki
mesh_terms: D000103:Acetyl-CoA Carboxylase / Q000235:genetics; D000273:Adipose Tissue / Q000502:physiology; D000818:Animals; D001835:Body Weight; D022762:CCAAT-Enhancer-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D004041:Dietary Fats / Q000008:administration & dosage / Q000378:metabolism; D064429:Fatty Acid Synthases / Q000235:genetics; D005260:Female; D005395:Fish Oils / Q000008:administration & dosage* / Q000378:metabolism; D008099:Liver / Q000737:chemistry / Q000166:cytology / Q000378:metabolism / Q000502:physiology*; D051379:Mice; D008810:Mice, Inbred C57BL; D018482:Muscle, Skeletal / Q000502:physiology; D009765:Obesity / Q000378:metabolism*; D009929:Organ Size; D012333:RNA, Messenger / Q000378:metabolism*; D018160:Receptors, Cytoplasmic and Nuclear / Q000378:metabolism; D013230:Stearoyl-CoA Desaturase / Q000235:genetics; D051780:Sterol Regulatory Element Binding Protein 1; D013347:Subcellular Fractions / Q000737:chemistry / Q000378:metabolism; D014157:Transcription Factors / Q000378:metabolism
chemical_list: D022762:CCAAT-Enhancer-Binding Proteins; D004268:DNA-Binding Proteins; D004041:Dietary Fats; D005395:Fish Oils; D012333:RNA, Messenger; D018160:Receptors, Cytoplasmic and Nuclear; C497388:Srebf1 protein, mouse; D051780:Sterol Regulatory Element Binding Protein 1; D014157:Transcription Factors; D013230:Stearoyl-CoA Desaturase; D064429:Fatty Acid Synthases; D000103:Acetyl-CoA Carboxylase