Lack of stearoyl-CoA desaturase-1 function induces a palmitoyl-CoA Δ6 desaturase and represses the stearoyl-CoA desaturase-3 gene in the preputial glands of the mouse

A higher content of C16:1 n-10 has recently been reported in the preputial gland of mice with a targeted disruption of the gene encoding stearoyl-CoA desaturase 1 (SCD1 ؊ / ؊ mice) when compared with wild-type mice. This result has provided the first physiological evidence for the presence and regulation of a palmitoyl-CoA ⌬ 6-desaturase in mammals. To investigate the putative involvement of the known ⌬ 6-desaturase (FADS2) in this process, COS-7 cells expressing rat ⌬ 6-desaturase were incubated with C16:0. Transfected cells were able to synthesize C16:1 n-10, while nontransfected cells did not produce any C16:1 n-10. Evidence is therefore presented that the rat ⌬ 6-desaturase, which acts on the 18-and 24-carbon fatty acids of the n-6 and n-3 series, is also able to catalyze palmitic acid ⌬ 6-desaturation. The presence of a palmitoyl-CoA ⌬ 6-desaturase has recently been described in mice (1). This unexpected ⌬ 6-desaturase activity was found in mice deficient for stearoyl-CoA desaturase 1 (SCD1 Ϫ / Ϫ mice). However, this palmitoyl-CoA ⌬ 6-desaturase activity has not yet been ascribed to any known desaturase gene.The ⌬ 6-desaturase (FADS2) has been cloned in several mammalian species (2, 3). In a previous work (4), we reported that recombinant rat ⌬ 6-desaturase expressed in COS-7 cells acts on 18-and 24-carbon fatty acids of the n-3 and n-6 series in polyunsaturated fatty acid (PUFA) biosynthesis. This result, consistent with experiments performed in yeast (5) and the PUFA biosynthetic pathway initially proposed by Sprecher and coworkers (6), illustrated the broad chain length specificity of the ⌬ 6-desaturase.In the present work, we investigated the putative involvement of FADS2 protein in the ⌬ 6-desaturation of palmitic acid. We established that C16:0 is desaturated to C16:1 n-10 by COS-7 cells when expressing rat ⌬ 6-desaturase. Moreover, coexpression of both ⌬ 6-desaturase and SCD1 resulted in both ⌬ 6-and ⌬ 9-desaturation of palmitic acid. Therefore, this study reports for the first time that a single gene encodes a mammalian ⌬ 6-desaturase that acts on one saturated fatty acid in addition to act on PUFAs. MATERIALS AND METHODS ChemicalsFetal calf serum (FCS) was purchased from Perbio (Bezons, France). Solvents were purchased from Fischer Scientific (Elancourt, France). Fatty acids and other reagents were from Sigma (St Quentin Fallavier, France). Radiolabeled [1-14 C]palmitic acid was purchased from Perkin Elmer Life Sciences (Paris, France). The anti-rat liver ⌬ 9-desaturase serum was a generous gift from Dr J. Ozols (7). Plasmid construction for expression of rat ⌬ 6-and ⌬ 9-desaturasesThe plasmid constructed for expression of rat ⌬ 6-desaturase in mammalian cells (referred to as pCMV/ ⌬ 6) has already been described (4). A plasmid coding for rat ⌬ 9-desaturase (SCD1) was constructed for expression in mammalian cells and is referred to as pcDNA3/ ⌬ 9. From the published (8) rat SCD1 sequence (GenBank accession number J02585), oligonucleotide primers were designed to PCR amplify the entire codi...

Section: Discussionmentioning

confidence: 99%

“…The presence of a palmitoyl-CoA ⌬ 6-desaturase has recently been described in mice (1). This unexpected ⌬ 6-desaturase activity was found in mice deficient for stearoyl-CoA desaturase 1 (SCD1 Ϫ / Ϫ mice).…”

mentioning

confidence: 99%

Conversion of hexadecanoic acid to hexadecenoic acid by rat Δ6-desaturase

Guillou¹,

Rioux²,

Catheline³

et al. 2003

“…While mouse SCD1 is expressed at high levels in adipose tissue and is induced in liver under high-carbohydrate conditions, SCD3 expression is restricted to skin, Harderian gland, and the preputial gland (17)(18)(19). We took advantage of the substrate preferences of distinct SCD isoforms to restore oleate (human SCD5) or palmitoleate (mouse SCD3) synthesis in the liver only in GKO mice.…”

Section: Liver Histologymentioning

confidence: 99%

Hepatic oleate regulates adipose tissue lipogenesis and fatty acid oxidation

Burhans

Flowers

Harrington

et al. 2015

Self Cite

This article is available online at http://www.jlr.orgRecently, the prevalence of overweight among all adults in the US was estimated to be nearly 70% ( 1 ), and has increased more than 2-fold since 1980 ( 2 ). With increased adiposity, lipids accumulate ectopically and are associated with increased risk for detrimental metabolic conditions such as nonalcoholic fatty liver disease, insulin resistance, and hypertriglyceridemia ( 3-5 ). The balance of lipid storage between liver and adipose depots may play an important role in disease vulnerability. Fat may be synthesized from dietary carbohydrates via de novo lipogenesis (DNL), or sequestered from circulating lipids. The contribution of hepatic and adipose tissue DNL-derived fat to wholebody adiposity is controversial. While it is considered to be quantitatively minimal by some ( 6, 7 ), others have demonstrated that DNL-derived lipids can negatively impact metabolic health and contribute to hepatic steatosis and visceral adiposity in humans ( 8-10 ). Of particular importance in the context of whole-body metabolic homeostasis, recent evidence suggests that de novo synthesized fatty acids and lipids serve important signaling and regulatory roles in cellular and systemic metabolism ( 7,11 ).MUFAs are major components of tissue lipids such as TGs, cholesteryl esters (CEs), and GPs , and high levels of MUFAs are inversely associated with metabolic health. The stearoyl-CoA desaturase (SCD) family of enzymes catalyzes the synthesis of MUFAs by insertion of a cis double bond at the ⌬ 9 position of saturated fatty acids. DK062388, ADA 7-13-BS-118, and USDA Hatch W2005 (to J.M.N.), and NIH Grant RO1 AG037000 (to R.M.A.) Abbreviations: ASM, acid soluble metabolite; CE, cholesteryl ester; DNL, de novo lipogenesis; GKO, stearoyl-CoA desaturase 1 global knockout; GLC, gas liquid chromatography; GLS5, global knockout liver-specifi c stearoyl-CoA desaturase 5 transgenic; GLS3, global knockout liver-specifi c stearoyl-CoA desaturase 3 transgenic; LD, lipogenic diet; LKO, stearoyl-CoA desaturase 1 liver knockout; SCD, stearoyl-CoA desaturase; WAT, white adipose tissue .1 To whom correspondence should be addressed. e-mail: jmntambi@wisc.edu The online version of this article (available at http://www.jlr.org) contains supplementary data in the form of three fi gures and nine tables. METHODS Animals and dietsTwo liver transgenic mouse lines were generated by cloning either the human SCD5 cDNA sequence or the mouse SCD3 cDNA sequence into the pLiv.LE6 vector construct (a kind gift from John Taylor, Gladstone Institute) ( 20 ). Mice were backcrossed at least seven generations with C57BL/6 mice to generate SCD5Tg+ and SCD3Tg+ mice. SCD5Tg+ and SCD3Tg+ mice were then crossed with SCD1 GKO mice (in C57BL/6 background) to generate compound heterozygous mice, SCD1+/ Ϫ carrying one copy of the SCD5 or SCD3 transgene. These compound heterozygous mice were then bred with female SCD1+/ Ϫ or male SCD1 Ϫ / Ϫ mice to generate SCD5Tg+;SCD1 Ϫ / Ϫ (GLS5) and SCD3Tg+;SCD1 Ϫ / Ϫ (GLS3) mice.Mice wer...

“…Exogenous saturated fatty acids (0.2 mM) were added into YPD in the presence of 1% Tergitol NP-40 (Sigma). The double bond positions of the monounsaturated fatty acid methyl ester were determined by GC-MS analysis of the dimethyl disulfide derivatives (11,22).…”

Section: Fatty Acid Analysismentioning

confidence: 99%

“…SCD2 is expressed primarily in the brain and neuronal tissue, particularly during the neonatal mylenation period (6). SCD3 expression is restricted to sebocytes in skin, preputial gland, and Harderian gland (9)(10)(11). SCD4 is expressed predominantly in heart (7).…”

mentioning

confidence: 99%

Identification of mouse palmitoyl-coenzyme A Δ9-desaturase

Miyazaki

Bruggink

Ntambi

2006

Self Cite

115

101

Stearoyl-coenzyme A desaturase (SCD) catalyzes the desaturation of saturated fatty acids to monounsaturated fatty acids in mammalian cells. Currently, there are four known enzymatic isoforms (SCD1-SCD4) in the mouse genome. The physiological roles for multiple SCD isoforms and their substrate specificities are unknown at present. We report here distinct substrate specificities for the mouse SCD isoforms. Each SCD isoform was able to complement the ole1 mutation in Saccharomyces cerevisiae through heterologous expression of transgenic SCD. Fatty acid analysis showed that mouse SCD1, SCD2, and SCD4 desaturate both C18:0 and C16:0, whereas mouse SCD3 uses C16:0 but not C18:0.We identify SCD3 as a mammalian palmitotyl-CoA D9-desaturase, and its existence in mouse helps explain distinct physiological roles for each SCD isoform. Supplementary key words stearoyl-CoA desaturase . oleate . palmitoleate . substrate specificity D9-desaturase is a fatty acid-modifying enzyme in the biosynthesis of monounsaturated fatty acids. Because this enzyme commonly introduces a cis double bond at the 9,10 position of stearoyl-CoA to form oleoyl-CoA, it has been commonly known as stearoyl-coenzyme A desaturase (SCD) (1-5). Four SCD isoforms (SCD1-SCD4) have been characterized in mice (6-9). All mouse SCD genes are colocalized to chromosome 19 (9).Despite the fact that the four SCD isoforms share .75% nucleotide and amino acid sequence identities, they differ in their 59-flanking promoter, which results in divergent tissue-specific expression (2). SCD1 is expressed in lipogenic tissues, including liver and adipose tissue (8). SCD2 is expressed primarily in the brain and neuronal tissue, particularly during the neonatal mylenation period (6). SCD3 expression is restricted to sebocytes in skin, preputial gland, and Harderian gland (9-11). SCD4 is expressed predominantly in heart (7). Mouse SCD1 and SCD2 are the best characterized isoforms because of the availability of SCD1 and SCD2 knockout mice (SCD1 2/2 and SCD2 2/2 ) (12, 13). Adult SCD1 2/2 mice exhibit a decrease in the synthesis of esterified lipids, including triglycerides, cholesteryl esters, and wax esters. As a consequence, SCD12/2 mice are protected against adiposity and liver steatosis, but they develop alopecia and close eye fissure (12,14,15). In contrast, SCD2 mice have a defect in skin permeability barrier formation and show a decrease in the synthesis of lipids during early development but not at late stages of development (13). These results have suggested that although SCD1 is crucial in adult mice, SCD2 controls lipid metabolism in early life.Currently, it is unknown why multiple SCD isoforms exist in mammalian genomes. Both the tissue-specific expression and the resulting phenotypes of SCD1 and SCD2 mouse isoform knockouts suggest that each isoform has a distinct physiological role; however, it is not clear how the enzymes accomplish the different roles biochemically. Liver microsomes from SCD1 2/2 and SCD2 2/2 mice displayed a decrease in the conversions of...