title: Synthesis of the suspected trans-11,cis-13 conjugated linoleic acid isomer in ruminant mammary tissue by FADS3-catalyzed Δ13-desaturation of vaccenic acid.
abstract: The octadecadienoic conjugated linoleic acid (CLA) isomer with trans-11 and cis-13 double bonds (trans-11,cis-13 CLA) has been described in ruminant milk. For now, this specific CLA is suspected to derive exclusively from ruminal biohydrogenation of dietary α-linolenic acid. However, in rodents, the fatty acid desaturase 3 (FADS3) gene was recently shown to code for an enzyme able to catalyze the unexpected Δ13-desaturation of vaccenic acid, producing a Δ11,13-CLA with all the structural characteristics of the trans-11,cis-13 isomer, although no commercial standard exists for complete conclusive identification. Because the FADS3 gene has already been reported in bovine animals, we hypothesized in the present study that an alternative direct FADS3-catalyzed Δ13-desaturation of vaccenic acid in mammary tissue may therefore co-exist with α-linolenic acid biohydrogenation to explain the final ruminant milk trans-11,cis-13 CLA presence. Here, we first confirm that the FADS3 gene is present in ruminant mammal genomic sequence databases. Second, we demonstrate that the Δ11,13-CLA found in milk fat and the highly probable trans-11,cis-13 CLA isomer produced by rodent FADS3 possess exactly the same structural characteristics. Then, we show that bovine mammary MAC-T and BME-UV epithelial cells express both FADS3 and stearoyl-CoA desaturase 1 (SCD1) mRNA and are able to synthesize both the suspected trans-11,cis-13 CLA and cis-9,trans-11CLA (rumenic acid) isomers when incubated with vaccenic acid. Finally, the concomitant presence of the suspected trans-11,cis-13 CLA isomer with FADS3 mRNA was shown in goat mammary tissue, whereas both were conversely very low or even absent in goat liver. Therefore, this study provides several lines of evidence that, by analogy with rumenic acid, trans-11,cis-13 CLA may originate both from ruminal biohydrogenation and from direct FADS3-catalyzed Δ13-desaturation of vaccenic acid in mammary tissue.
authors.affiliation: Laboratoire de Biochimie Agrocampus Ouest-INRA, USC1378, 35000 Rennes, France.
authors.forename: Cyrielle
authors.initials: C
authors.lastname: Garcia
authors.affiliation: Laboratoire de Biochimie Agrocampus Ouest-INRA, USC1378, 35000 Rennes, France.
authors.forename: Cécile
authors.initials: C
authors.lastname: Duby
authors.affiliation: Laboratoire de Biochimie Agrocampus Ouest-INRA, USC1378, 35000 Rennes, France.
authors.forename: Daniel
authors.initials: D
authors.lastname: Catheline
authors.affiliation: INRA, UR1213 Herbivores, 63122 Saint-Genès-Champanelle, France.
authors.forename: Pablo G
authors.initials: PG
authors.lastname: Toral
authors.affiliation: INRA, UR1213 Herbivores, 63122 Saint-Genès-Champanelle, France.
authors.forename: Laurence
authors.initials: L
authors.lastname: Bernard
authors.affiliation: Laboratoire de Biochimie Agrocampus Ouest-INRA, USC1378, 35000 Rennes, France.
authors.forename: Philippe
authors.initials: P
authors.lastname: Legrand
authors.affiliation: Laboratoire de Biochimie Agrocampus Ouest-INRA, USC1378, 35000 Rennes, France. Electronic address: vincent.rioux@agrocampus-ouest.fr.
authors.forename: Vincent
authors.initials: V
authors.lastname: Rioux
mesh_terms: D000821:Animal Feed / Q000032:analysis; D000818:Animals; D002417:Cattle; D004032:Diet / Q000662:veterinary; D004847:Epithelial Cells / Q000187:drug effects / Q000378:metabolism; D044943:Fatty Acid Desaturases / Q000235:genetics / Q000378:metabolism*; D005260:Female; D006041:Goats; D007536:Isomerism; D044243:Linoleic Acids, Conjugated / Q000032:analysis / Q000096:biosynthesis*; D008321:Mammary Glands, Animal / Q000378:metabolism*; D008892:Milk / Q000737:chemistry; D009829:Oleic Acids / Q000378:metabolism*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D013230:Stearoyl-CoA Desaturase / Q000235:genetics / Q000378:metabolism; D017962:alpha-Linolenic Acid / Q000008:administration & dosage
chemical_list: D044243:Linoleic Acids, Conjugated; D009829:Oleic Acids; D012333:RNA, Messenger; D017962:alpha-Linolenic Acid; C046938:9,11-linoleic acid; D044943:Fatty Acid Desaturases; D013230:Stearoyl-CoA Desaturase; C073651:delta-13 fatty acid desaturase; C050413:11-octadecenoic acid
keywords: fatty acid desaturase 3; stearoyl-CoA desaturase 1; trans-11,cis-13 conjugated linoleic acid; vaccenic acid