Cynthia Chatterjee1,2, Jiajie Liu1, Carla Wood1, Christine Gagnon2, Elroy R Cober2, Judith A Frégeau-Reid2, Stephen Gleddie2, Chao-Wu Xiao3,4. 1. Nutrition Research Division, Food Directorate, Health Products and Food Branch, Health Canada, Banting Research Centre, 251 Sir Frederick Banting Drive, Ottawa, ON, K1A 0K9, Canada. 2. Ottawa Research & Development Centre, Central Experimental Farm, Agriculture and Agri-Food Canada, 960 Carling Avenue Building#21, Ottawa, ON, K1A 0C6, Canada. 3. Nutrition Research Division, Food Directorate, Health Products and Food Branch, Health Canada, Banting Research Centre, 251 Sir Frederick Banting Drive, Ottawa, ON, K1A 0K9, Canada. chaowu.xiao@hc-sc.gc.ca. 4. Food and Nutrition Science Program, Department of Chemistry, Carleton University, 1125 Colonel By Drive, Ottawa, ON, K1S 5B6, Canada. chaowu.xiao@hc-sc.gc.ca.
Abstract
PURPOSE: This study examined the effect of soy proteins with depletion of different subunits of the two major storage proteins, β-conglycinin and glycinin, on hepatic lipids and proteins involved in lipid metabolism in rats, since the bioactive component of soy responsible for lipid-lowering is unclear. METHODS: Weanling Sprague Dawley rats were fed diets containing either 20% casein protein in the absence (casein) or presence (casein + ISF) of isoflavones or 20% alcohol-washed soy protein isolate (SPI) or 20% soy protein concentrates derived from a conventional (Haro) or 2 soybean lines lacking the α' subunit of β-conglycinin and the A1-3 (1TF) or A1-5 (1a) subunits of glycinin. After 8 weeks, the rats were necropsied and liver proteins and lipids were extracted and analysed. RESULTS: The results showed that soy protein diets reduced lipid droplet accumulation and content in the liver compared to casein diets. The soy protein diets also decreased the level of hepatic mature SREBP-1 and FAS in males, with significant decreases in diets 1TF and 1a compared to the casein diets. The effect of the soy protein diets on female hepatic mature SREBP-1, FAS, and HMGCR was confounded since casein + ISF decreased these levels compared to casein alone perhaps muting the decrease by soy protein. A reduction in both phosphorylated and total STAT3 in female livers by ISF may account for the gender difference in mechanism in the regulation and protein expression of the lipid modulators. CONCLUSIONS: Overall, soy protein deficient in the α' subunit of β-conglycinin and A1-5 subunits of glycinin maintain similar hypolipidemic function compared to the conventional soy protein. The exact bioactive component(s) warrant identification.
PURPOSE: This study examined the effect of soy proteins with depletion of different subunits of the two major storage proteins, β-conglycinin and glycinin, on hepatic lipids and proteins involved in lipid metabolism in rats, since the bioactive component of soy responsible for lipid-lowering is unclear. METHODS: Weanling Sprague Dawley rats were fed diets containing either 20% casein protein in the absence (casein) or presence (casein + ISF) of isoflavones or 20% alcohol-washed soy protein isolate (SPI) or 20% soy protein concentrates derived from a conventional (Haro) or 2 soybean lines lacking the α' subunit of β-conglycinin and the A1-3 (1TF) or A1-5 (1a) subunits of glycinin. After 8 weeks, the rats were necropsied and liver proteins and lipids were extracted and analysed. RESULTS: The results showed that soy protein diets reduced lipid droplet accumulation and content in the liver compared to casein diets. The soy protein diets also decreased the level of hepatic mature SREBP-1 and FAS in males, with significant decreases in diets 1TF and 1a compared to the casein diets. The effect of the soy protein diets on female hepatic mature SREBP-1, FAS, and HMGCR was confounded since casein + ISF decreased these levels compared to casein alone perhaps muting the decrease by soy protein. A reduction in both phosphorylated and total STAT3 in female livers by ISF may account for the gender difference in mechanism in the regulation and protein expression of the lipid modulators. CONCLUSIONS: Overall, soy protein deficient in the α' subunit of β-conglycinin and A1-5 subunits of glycinin maintain similar hypolipidemic function compared to the conventional soy protein. The exact bioactive component(s) warrant identification.
Authors: Douglas G Mashek; Salmaan A Khan; Aishwarya Sathyanarayan; Jonathan M Ploeger; Mallory P Franklin Journal: Hepatology Date: 2015-05-09 Impact factor: 17.425
Authors: T Akiyama; J Ishida; S Nakagawa; H Ogawara; S Watanabe; N Itoh; M Shibuya; Y Fukami Journal: J Biol Chem Date: 1987-04-25 Impact factor: 5.157