title: Collagen peptide ingestion alters lipid metabolism-related gene expression and the unfolded protein response in mouse liver.
abstract: Ingestion of collagen peptide (CP) elicits beneficial effects on the body, including improvement in blood lipid profiles, but the underlying mechanisms remain unclear. The purpose of this study was to investigate the effects of CP ingestion on the liver, which controls lipid metabolism in the body. Male BALB/cCrSlc mice were bred with the AIN-93M diet containing 14 % casein or the AIN-93M-based low-protein diet containing 10 % casein or a diet containing 6 % casein+4 % CP for 10 weeks (n 12/group). Total, free and esterified cholesterol levels in the blood decreased in the CP group. DNA microarray analysis of the liver revealed that expressions of genes related to lipid metabolic processes such as the PPAR signalling pathway and fatty acid metabolism increased in the CP group compared with the 10 % casein group. The expressions of several genes involved in steroid metabolic process, including Cyp7a1 and Cyp8b1, were decreased, despite being targets of transcriptional regulation by PPAR. These data suggest that lipid metabolism in the liver is altered by CP ingestion, and the decrease in blood cholesterol levels in the CP group is not due to enhancement of the steroid metabolic process. On the other hand, expressions of genes related to the unfolded protein response (UPR) significantly decreased at the mRNA level, suggesting that CP ingestion lowers endoplasmic reticulum stress. Indeed, protein levels of phosphorylated inositol-requiring enzyme 1 decreased after CP ingestion. Taken together, CP affects the broader pathways in the liver - not only lipid metabolism but also UPR.
authors.affiliation: 1Research Institute of Biomatrix,Nippi Inc.,520-11 Kuwabara,Toride,Ibaraki 302-0017,Japan.
authors.forename: Chisa
authors.initials: C
authors.lastname: Tometsuka
authors.affiliation: 1Research Institute of Biomatrix,Nippi Inc.,520-11 Kuwabara,Toride,Ibaraki 302-0017,Japan.
authors.forename: Yoh-Ichi
authors.initials: YI
authors.lastname: Koyama
authors.affiliation: 2Graduate School of Agricultural and Life Sciences,The University of Tokyo,1-1-1 Yayoi,Bunkyo-ku, Tokyo 113-8657,Japan.
authors.forename: Tomoko
authors.initials: T
authors.lastname: Ishijima
authors.affiliation: 2Graduate School of Agricultural and Life Sciences,The University of Tokyo,1-1-1 Yayoi,Bunkyo-ku, Tokyo 113-8657,Japan.
authors.forename: Tsudoi
authors.initials: T
authors.lastname: Toyoda
authors.affiliation: 3Department of Veterinary Microanatomy,School of Veterinary Medicine,Rakuno Gakuen University,582 Bunkyodai-Midorimachi,Ebetsu,Hokkaido 069-8601,Japan.
authors.forename: Miki
authors.initials: M
authors.lastname: Teranishi
authors.affiliation: 3Department of Veterinary Microanatomy,School of Veterinary Medicine,Rakuno Gakuen University,582 Bunkyodai-Midorimachi,Ebetsu,Hokkaido 069-8601,Japan.
authors.forename: Kazushige
authors.initials: K
authors.lastname: Takehana
authors.affiliation: 2Graduate School of Agricultural and Life Sciences,The University of Tokyo,1-1-1 Yayoi,Bunkyo-ku, Tokyo 113-8657,Japan.
authors.forename: Keiko
authors.initials: K
authors.lastname: Abe
authors.affiliation: 2Graduate School of Agricultural and Life Sciences,The University of Tokyo,1-1-1 Yayoi,Bunkyo-ku, Tokyo 113-8657,Japan.
authors.forename: Yuji
authors.initials: Y
authors.lastname: Nakai
mesh_terms: D000284:Administration, Oral; D000818:Animals; D003094:Collagen / Q000008:administration & dosage / Q000494:pharmacology*; D005786:Gene Expression Regulation / Q000187:drug effects*; D050356:Lipid Metabolism / Q000235:genetics / Q000502:physiology*; D008099:Liver / Q000378:metabolism*; D008297:Male; D051379:Mice; D056811:Unfolded Protein Response / Q000187:drug effects*
chemical_list: D003094:Collagen
keywords:  10C AIN-93M-based low-protein diet containing 10 % protein (as casein);  6C+4CP AIN-93M-based low-protein diet containing 6 % protein (as casein) plus 4 % protein (as collagen peptide);  CP collagen peptide;  GO Gene Ontology;  IRE1 inositol-requiring enzyme 1;  cDNA complementary DNA;  p-IRE1 phospho-IRE1; Collagen peptide; DNA microarray; Lipid metabolism; Liver; Unfolded protein response