Trans10, cis12-conjugated linoleic acid prevents triacylglycerol accumulation in adipocytes by acting as a PPARgamma modulator

A group of polyunsaturated fatty acids called conjugated linoleic acids (CLAs) are found in ruminant products, where the most common isomers are cis9, trans11 (c 9,t11) and trans10, cis12 (t10,c12) CLA. A crude mixture of these isomers has been shown in animal studies to alter body composition by a reduction in body fat mass as well as an increase in lean body mass, with the t10,c12 isomer having the most pronounced effect. The objective of this study was to establish the molecular mechanisms by which t10,c12 CLA affects lipid accumulation in adipocytes. We have shown that t10,c12 CLA prevents lipid accumulation in human and mouse adipocytes at concentrations as low as 5 microM and 25 microM, respectively. t10,c12 CLA fails to activate peroxisome proliferator-activated receptor gamma (PPARgamma) but selectively inhibits thiazolidinedione-induced PPARgamma activation in 3T3-L1 adipocytes. Treatment of mature adipocytes with t10,c12 CLA alone or in combination with Darglitazone down-regulates the mRNA expression of PPARgamma as well as its target genes, fatty acid binding protein (aP2) and liver X receptor alpha (LXRalpha). Taken together, our results suggest that the trans10, cis12 CLA isomer prevents lipid accumulation in adipocytes by acting as a PPARgamma modulator.     

Isomers of conjugated linoleic acid modulate human preadipocyte differentiation

Conjugated linoleic acids (CLAs) reduce fat deposition in several mammalian species. Among the proposed mechanisms for this effect are reduced preadipocyte proliferation and differentiation. We measured proliferation and differentiation of cultured human preadipocytes treated with CLAs. Preadipocytes were differentiated with insulin, hydrocortisone, transferrin, and 10% fetal bovine serum, with isobutyl-methylxanthine included for the first 2 d. The differentiation medium contained 200 microM oleic acid (C18:1), 50 microM cis-9,trans-11-CLA (9,11-CLA), or 50 microM trans-10,cis-12-CLA (10,12-CLA); the negative control medium contained no added fatty acid, and the cells did not differentiate. Cell number increased three to four times during the 17 d of differentiation, but was 30-35% lower in the CLA-treated cells than in the negative control cells. Compared with the negative control cells, differentiation was increased in the cells treated with C18:1 (increased Oil Red O-stained material [OROSM], triacylglycerol, glycerol 3-phosphate dehydrogenase activity [GPDH], peroxisome proliferator-activated receptor-gamma [PPAR gamma] messenger ribonucleic acid [mRNA], and lipoprotein lipase [LPL] mRNA). In effect, the C18:1-treated cells act as a positive control to demonstrate the differentiation capacity of each cell lot. Both 9,11-CLA- and 10,12-CLA-treated cells had increased differentiation (increased OROSM, triacylglycerol, GPDH, PPAR gamma, and LPL) compared with the negative control cells. The data suggest that early in differentiation when de novo fatty acid (FA) synthesis is limited and competition for FAs by membrane and triacylglycerol synthetic pathways is great, human preadipocytes do not differentiate unless a PPAR gamma ligand is added. Either CLA isomer or C18:1 can provide such a ligand.     

Conjugated linoleic acids promote human fat cell apoptosis.

Conjugated linoleic acids (CLAs) are conjugated dienoic isomers of linoleic acid. Some isomers have been shown to reduce fat mass in animal and cell culture models. However, controversial results were obtained in studies of supplementation of CLAs in human subjects. In order to get more insights into the direct effects of CLAs on human fat cells, we have studied the influence of cis-9, trans-11 CLA and trans-10, cis-12 CLA on the biology of human SGBS preadipocytes and adipocytes. Both CLA isomers equally inhibited the proliferation of preadipocytes in a dose-dependent manner. Continuous treatment with 1-10 microM trans-10, cis-12 CLA, and to a weaker extent cis-9, trans-11 CLA, inhibited accumulation of lipids during adipogenic differentiation. Treatment with higher doses of CLA induced apoptosis in preadipocytes, in differentiating cells, and adipocytes. The trans-10, cis-12 isomer had a higher apoptotic potency in adipocytes than cis-9, trans-11 CLA. Taken together, the treatment of human preadipocytes and adipocytes with physiological relevant concentrations of CLAs resulted in an impairment of proliferation and differentiation and induction of apoptosis. The trans-10, cis-12 isomer was more potent than the cis-9, trans-11 isomer. Further clinical studies are needed to evaluate the effects of CLAs on human fat mass and metabolism in vivo.     

Isomer-specific effects of conjugated linoleic acid on mineralized bone nodule formation from human osteoblast-like cells

Mixed isomers of conjugated linoleic acid (CLA) have been shown to have variable effects on bone formation and resorption in animals. The variable effects of CLA on bone physiology may be due to the different isomers present in common commercial preparations of CLA, and the effects of the predominant individual isomers (9cis,11trans and 10trans,12cis CLA) are not clear. The objective of this study was to determine the effects of individual and mixed isomers of CLA on mineralized bone nodule formation and alkaline phosphatase (ALP) activity in vitro using long-term cultures of SaOS-2 cells. Mineralized bone nodules were stained using the von Kossa method, and ALP activity in cell lysates was measured as a marker of early osteoblast differentiation. The 9cis,11trans isomer increased the number (~4- to 11-fold) and size (~2- to 5-fold) of mineralized bone nodules from 25 to 100 microM, but the 10trans,12cis isomer did not. The increase in mineralized bone nodule formation by 9cis,11trans CLA was accompanied by a variable increase in ALP activity. These results show that the 9cis,11trans isomer of CLA increases the formation of mineralized bone nodules using bone cells of human origin, and provide evidence for isomer-specific effects of CLA on bone health.     

The effect of conjugated linoleic acid on arachidonic acid metabolism and eicosanoid production in human saphenous vein endothelial cells

The effects of a conjugated linoleic acid (CLA) mixture of single isomers (50:50, w/w, cis9,trans11:trans10,cis12) and the individual isomers on (a) the production of resting and calcium ionophore stimulated (14)C-eicosanoids and (b) the incorporation of (14)C-arachidonic acid (AA) into membrane phospholipids of human saphenous vein endothelial cells were investigated. The CLA mixture and the individual isomers were found to inhibit resting production of (14)C-prostaglandin F(2a) by 50, 43 and 40%, respectively. A dose dependent inhibition of stimulated (14)C-prostaglandins was observed with the CLA mixture (IC(50) 100 microM). The cis9,trans11 and trans10,cis12 (50 microM) isomers individually inhibited the overall production of stimulated (14)C-prostaglandins (between 35 and 55% and 23 and 42%, respectively). When tested at a high concentration (100 microM), cis9,trans11 was found to inhibit eicosanoid production in contrast to trans10,cis12 that caused stimulation. The overall degree of (14)C-AA incorporation into membrane phospholipids of the CLA (mixture and individual isomers) treated cells was found to be lower than that of control cells and the cis9,trans11 isomer was found to increase the incorporation of (14)C-AA into phosphatidylcholine. Docosahexaenoic acid, eicosapentaenoic acid and linoleic acid did not alter the overall degree of incorporation of (14)C-AA. The results of this study suggest that both isomers inhibit eicosanoid production, and although trans10,cis12 exhibits pro-inflammatory activity at high concentrations, the CLA mixture maintains its beneficial anti-inflammatory action that contributes to its anti-carcinogenic and anti-atherogenic properties.     

The effect of conjugated linoleic acid on the viability and metabolism of human osteoblast-like cells

Studies in experimental animals and murine osteoblast cells in culture have produced conflicting findings on the effect of conjugated linoleic acid (CLA) on bone formation. The present study investigated the influence of CLA on viability and metabolism of two human osteoblast-like cell lines (SaOS2 and MG63). Both cell lines were exposed to increasing concentrations (0-50 microM) of CLA either as pure cis (c) 9: trans (t) 11 and t10:c12 CLA isomers or a blend of isomers, or linoleic acid (C18:2). Cell cytotoxicity and degree of DNA fragmentation were unaffected by any fatty acid treatment. PGE2 biosynthesis by both cell lines was variably reduced by CLA isomer blend and t10:c12 CLA, but not c9:t11 CLA. Alkaline phosphatase activity was variably increased by all CLA treatments. These results suggest a lack of cytotoxic effect of CLA on human osteoblast-like cells and tentatively suggest a possible beneficial effect on bone formation in humans.     

Linoleic acid partially restores the triglyceride content of conjugated linoleic acid-treated cultures of 3T3-L1 preadipocytes

We have previously demonstrated that a crude mixture of commercially available conjugated linoleic acid (CLA) isomers suppressed triglyceride (TG) content and induced apoptosis in post-confluent cultures of murine 3T3-L1 preadipocytes. Furthermore, we found that 100 μM of trans-10, cis-12 isomer of CLA had a greater TG-lowering and apoptotic effect than the crude mixture of CLA isomers. Therefore, the purpose of this study was to: 1) compare the potencies of the two main isomers found in the crude mixture of CLA isomers, e.g. cis-9, trans-11 (41%) and trans-10, cis-12 (44%); and 2) determine if the TG-reducing actions of CLA could be attenuated by the addition of increasing levels of linoleic acid to the cultures. Preadipocyte differentiation was assessed on day 7 of the differentiation protocol by measuring TG content (per 10⁶ cells), cell size, and lipid staining. In experiment 1, post-confluent cultures of 3T3-L1 preadipocytes treated for the first 6 d of differentiation with 100 μM of a crude mixture of CLA isomers or 44 μM of trans-10, cis-12 CLA had less TG content than all other cultures. In contrast, cultures supplemented with 41 μM of the cis-9, trans-11 CLA isomer had the same amount of TG as the BSA controls. In experiment 2, post-confluent cultures of 3T3-L1 preadipocytes treated for the first 6 d of differentiation with 50 μM trans-10, cis-12 CLA had less TG content and a greater number of smaller cells (10–12.5 microns) compared to all other treatments. CLA-treated cultures supplemented with increasing levels of linoleic acid (50–200 μM) had greater TG contents and greater numbers of larger cells (15–20 microns) than cultures treated with 50 μM of the trans-10, cis-12 CLA isomer alone. These data demonstrate that: 1) the TG-lowering effects of the crude mixture of CLA isomers is due almost exclusively to the trans-10, cis-12 isomer; and 2) linoleic acid partially reverses CLA’s attenuation of TG content, suggesting that these unsaturated fatty acids may compete for incorporation into TG or phospholipid-derived eicosanoids that regulate preadipocyte differentiation.     

Potentiation of the anti-tumour effect of docetaxel by conjugated linoleic acids (CLAs) in breast cancer cells in vitro

Response rates of tumours to docetaxel (DOCT) are 45-60% in advanced breast cancer but problems associated with side effects, drug resistance and high costs occur. Conjugated linoleic acids (CLAs) also have anti-tumorigenic activity that elicits similar changes in oncogene expression to DOCT and could augment DOCT efficacy. CLA isomers appear to differ in cytotoxicity toward cancer cells. Effects of two CLA isomers on cytotoxicity of DOCT in breast cancer cells (MCF-7; MDA-MB-231) in vitro were assessed. Cells were incubated up to 72 h with 40 microM each of LA or CLA isomers (cis-9, trans-10 CLA, or trans-10, cis-12 CLA) or a 50:50 isomer mix, alone or with DOCT (0-64 microM); a pilot study determined IC(50) and IC(70) concentrations. Treatments were concurrent (CLA and DOCT together) or sequential (CLA then DOCT). MTT assay determined cell viability. Trans-10, cis-12 CLA was the most effective fatty acid (P<0.001) and increased with treatment time. IC(50) and IC(70) concentrations of DOCT were determined, concurrently or sequentially, with and without fatty acids, in the two cell types. Concurrent treatment with trans-10, cis-12 CLA and DOCT augmented inhibition of cell growth in one or both cell lines (decreased IC(50) and IC(70) in MCF-7; P<0.05 but only IC(50) in MDA-MB-231; P<0.05). CLA mix reduced IC(50) and IC(70) in MDA-MB-231 (P<0.001) but not in MCF-7. Cis-9, trans-11 CLA and LA had no effect. Sequential treatment with CLAs then DOCT reduced IC(50) and IC(70) in MCF-7 but not in MDA-MB-231. The latter had increased IC(50) and IC(70) with LA treatment (P<0.05) and increased IC(70) with cis-9, trans-11 CLA (P<0.05) with sequential but not concurrent treatment. Longer pre-incubation times with trans-10, cis-12 CLA (24-72 h) elicited greater reductions in IC(50) and IC(70) in MCF-7 cells. Results show that CLA isomers augment anti-tumour effects of docetaxel in breast cancer cells and suggest possible dual treatment regimens.     

Effect of dietary conjugated linoleic acid and selenized yeast on the concentration of fatty acids and minerals in rats

The main objective of this study was to evaluate the influence of diets enriched in individual conjugated linoleic acid (CLA) isomers, their mixture, and/or selenized yeast (Se-yeast) on the concentration of CLA isomers, long-chain polyunsaturated fatty acids (PUFA) and Se in the heart, muscles and liver of rats. The investigation was performed on 73 female Wistar rats (8 weeks of age, 200 g initial BW). After one week sub-maintenance feeding, rats received diets supplemented with 1% individual CLA isomers or 1 or 2% of a CLA isomers mixture, without or with 1.2 mg Se/kg (as Se-yeast) for 29 days. Feeding diets with 2% CLA isomer mixture reduced feed intake and body weight gain of rats, while addition of trans10,cis12 CLA and Se-yeast resulted in the highest body weight gain. CLA supplementation generally elevated the concentration of CLA isomers in heart and muscles significantly, although cis9,trans11 CLA accumulated preferentially. Regardless of the presence of Se-yeast, the dietary enrichment with CLA isomers caused a reduction in the capacity of A9-desaturase. Addition of Se-yeast to diets with individual CLA isomers or a 1% mixture of CLA isomers elevated the accumulation of CLA isomers in the heart and muscles, whereas all treatments with supplemented CLA and Se-yeast increased the accumulation of Se in rats compared with animals fed the diet containing Se only. Furthermore, CLA isomer supplementation decreased the concentration of PUFA and total fatty acids in the heart and muscles compared with control rats. Moreover, addition of CLA isomers interfered in the conversion of linoleic and linolenic acids to higher metabolites due to competition of CLA isomers for the same enzymes (delta6-, delta5-, delta4-desaturases and elongase).     

CLA isomers inhibit TNFalpha-induced eicosanoid release from human vascular smooth muscle cells via a PPARgamma ligand-like action

Conjugated linoleic acids (CLAs) were reported to have anti-atherogenic properties in animal feeding experiments. In an attempt to elucidate the molecular mechanisms of these anti-atherogenic effects, the modulatory potential of CLA on cytokine-induced eicosanoid production from smooth muscle cells (SMCs), which contributes to the chronic inflammatory response associated with atherosclerosis, has been investigated in the present study. cis-9, trans-11 CLA and trans-10, cis-12 CLA were shown to reduce proportions of the eicosanoid precursor arachidonic acid in SMC total lipids and to inhibit cytokine-induced NF-kappaB DNA-binding activity, mRNA levels of inducible enzymes involved in eicosanoid formation (cPLA2, COX-2, mPGES), and the production of the prostaglandins PGE2 and PGI2 by TNFalpha-stimulated SMCs in a dose-dependent manner. The effect of 50 micromol/L of either CLA isomer was as effective as 10 micromol/L of the PPARgamma agonist troglitazone in terms of inhibiting the TNFalpha-stimulated eicosanoid production by SMCs. PPARgamma DNA-binding activity was increased by both CLA isomers compared to control cells. Moreover, it was shown that the PPARgamma antagonist T0070907 partially abrogated the inhibitory action of CLA isomers on cytokine-induced eicosanoid production and NF-kappaB DNA-binding activity by vascular SMCs suggesting that PPARgamma signalling is at least partially involved in the action of CLA in human vascular SMCs. With respect to the effects of CLA on experimental atherosclerosis, our findings suggest that the anti-inflammatory effect of CLA is at least partially responsible for the anti-atherogenic effects of CLA observed in vivo.     

Effect of dietary conjugated linoleic acid and selenized yeast on the concentration of fatty acids and minerals in rats

Abstract

The main objective of this study was to evaluate the influence of diets enriched in individual conjugated linoleic acid (CLA) isomers, their mixture, and/or selenized yeast (Se-yeast) on the concentration of CLA isomers, long-chain polyunsaturated fatty acids (PUFA) and Se in the heart, muscles and liver of rats. The investigation was performed on 73 female Wistar rats (8 weeks of age, 200 g initial BW). After one week sub-maintenance feeding, rats received diets supplemented with 1% individual CLA isomers or 1 or 2% of a CLA isomers mixture, without or with 1.2 mg Se/kg (as Se-yeast) for 29 days. Feeding diets with 2% CLA isomer mixture reduced feed intake and body weight gain of rats, while addition of trans10,cis12 CLA and Se-yeast resulted in the highest body weight gain. CLA supplementation generally elevated the concentration of CLA isomers in heart and muscles significantly, although cis9,trans11 CLA accumulated preferentially. Regardless of the presence of Se-yeast, the dietary enrichment with CLA isomers caused a reduction in the capacity of Δ9-desaturase. Addition of Se-yeast to diets with individual CLA isomers or a 1% mixture of CLA isomers elevated the accumulation of CLA isomers in the heart and muscles, whereas all treatments with supplemented CLA and Se-yeast increased the accumulation of Se in rats compared with animals fed the diet containing Se only. Furthermore, CLA isomer supplementation decreased the concentration of PUFA and total fatty acids in the heart and muscles compared with control rats. Moreover, addition of CLA isomers interfered in the conversion of linoleic and linolenic acids to higher metabolites due to competition of CLA isomers for the same enzymes (Δ6-, Δ5-, Δ4-desaturases and elongase).     

Troglitazone but not conjugated linoleic acid reduces gene expression and activity of matrix-metalloproteinases-2 and -9 in PMA-differentiated THP-1 macrophages

Gene expression and activity of matrix-metalloproteinases (MMP)-2 and -9 in macrophages are reduced through peroxisome proliferator-activated receptor gamma (PPARgamma)-dependent inhibition of NF-kappaB. Since conjugated linoleic acids (CLAs) are PPARgamma ligands and known to inhibit NF-kappaB via PPARgamma, we studied whether CLA isomers are capable of reducing gene expression and gelatinolytic activity of MMP-2 and -9 in PMA-differentiated THP-1 macrophages, which has not yet been investigated. Incubation of PMA-differentiated THP-1 cells with either c9t11-CLA, t10c12-CLA or linoleic acid (LA), as a reference fatty acid, resulted in a significant incorporation of the respective fatty acids into total cell lipids relative to control cells (P<.05). Treatment of PMA-differentiated THP-1 cells with 10 and 20 mumol/L troglitazone but not with 10 or 100 mumol/L c9t11-CLA, t10c12-CLA or LA reduced relative mRNA concentrations and activity of MMP-2 and MMP-9 compared to control cells (P<.05). DNA-binding activity of NF-kappaB and PPARgamma and mRNA expression of the NF-kappaB target gene cPLA(2) were not influenced by treatment with CLA. In contrast, treatment of PMA-differentiated THP-1 cells with troglitazone significantly increased transactivation of PPARgamma and decreased DNA-binding activity of NF-kappaB and relative mRNA concentration of cPLA(2) relative to control cells (P<.05). In conclusion, the present study revealed that CLA isomers, in contrast to troglitazone, did not reduce gene expression and activity of MMP-2 and -9 in PMA-differentiated THP-1 macrophages, which is probably explained by the observation that CLA isomers neither activated PPARgamma nor reduced DNA-binding activity of NF-kappaB. This suggests that CLA isomers are ineffective in MMP-associated extracellular matrix degradation which is thought to contribute to the progression and rupture of advanced atherosclerotic plaques.     

Conjugated linoleic acid metabolism

Conjugated linoleic acid (CLA) is a naturally occurring fatty acid that is produced by a bio-hydrogenation process in the rumen, and thus is present in dairy products and ruminant meat. In this case the predominant isomer formed is 9cis,11trans. However, CLA includes 28 positional and geometrical isomers, of which only 9cis,11trans and 10trans,12cis have thus far been proven to possess biological activities. Both of these CLA isomers have been shown to undergo elongation and desaturation processes similar to those that occur with linoleic acid, maintaining the conjugated diene structure. There are evidences supporting the hypothesis that CLA metabolism may interfere with eicosanoid formation. Other metabolites with 16 carbon atoms (conjugated 16:2 and 16:3, which are probably derived from peroxisomal beta-oxidation of CLA and its metabolites, respectively) have been detected. This suggests an efficient metabolism of CLA and its metabolites in peroxisomes, which might be linked to their capacity to activate peroxisome proliferator-activated receptors.     

Effects of structural changes of fatty acids on lipid accumulation in adipocytes and primary hepatocytes

Conjugated linoleic acids (CLAs), tetradecylthioacetic acid (TTA), eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) are all shown to differently affect lipid homeostasis. Additionally, previous studies have shown that introducing a methyl group in the molecule potentiates the hypolipidemic effect of EPA. The objective of this study was to determine how cis9,trans11 CLA, trans10,cis12 CLA, TTA, EPA and DHA affect lipid accumulation in 3T3-L1 adipocytes and in cultured primary rat hepatocytes, and to what extent changes in cis/trans configuration or introducing a methyl group in the molecules influence their way of affecting lipid accumulation in these cells. Our results show that trans10,cis12 CLA is highly specific in preventing lipid accumulation in adipocytes, and that small structural changes in the molecule (changing to trans/trans or introducing an alpha-methyl group) totally abolish this effect and up-regulate the expression levels of adipogenic marker genes towards control levels. Furthermore, all the fatty acids increased hepatic lipid accumulation, whereas the lipid content was normalized after adding an alpha-methyl group into the molecules. Taken together, our data demonstrate that the various fatty acids are highly specialized molecules, and that small structural changes markedly alter their way of affecting lipid accumulation in adipocytes and hepatocytes.     

Radiosensitizing effect of conjugated linoleic acid on tumor cells MCF-7 and MDA-MB-231

Apoptotic pathways in breast cancer cells are frequently altered, reducing the efficiency of radiotherapy. Conjugated linoleic acid (CLA), known to trigger apoptosis, was tested as radiosensitizer in breast cancer cells MCF-7 and MDA-MB-231. The CLA-mix, made up of the isomers CLA-9cis 11trans and CLA-10trans 12cis, was compared to three purified isomers, i.e., the CLA-9cis 11cis, CLA-9cis 11trans, and CLA-10trans 12cis. Using the apoptotic marker YO-PRO-1, the CLA-9cis 11cis at 50 micro mol/L turned out to be the best apoptotic inducer leading to a 10-fold increase in MCF-7 cells and a 2,5-fold increase in MDA-MB-231 cells, comparatively to the CLA-mix. Contrary to previous studies on colorectal and prostate cancer cells, CLA-10trans 12cis does not lead to an apoptotic response on breast cancer cell lines MCF-7 and MDA-MB-231. Our results also suggest that the main components of the CLA-mix (CLA-9cis 11trans and CLA-10trans 12cis) are not involved in the induction of apoptosis in the breast cancer cells studied. A dose of 5 Gy did not induce apoptosis in MCF-7 and MDA-MB-231 cells. The addition of CLA-9cis 11cis or CLA-mix has allowed us to observe a radiation-induced apoptosis, with the CLA-9cis 11cis being about 8-fold better than the CLA-mix. CLA-9cis 11cis turned out to be the best radiosensitizer, although the isomers CLA-9cis 11trans and CLA-10trans 12cis have also reduced the cell survival following irradiation, but using a mechanism not related to apoptosis. In conclusion, the radiosensitizing property of CLA-9cis 11cis supports its potential as an agent to improve radiotherapy against breast carcinoma.     

Impaired lipid accumulation by trans10, cis12 CLA during adipocyte differentiation is dependent on timing and length of treatment

Conjugated linoleic acids (CLAs) are a group of polyunsaturated fatty acids found in ruminant products, where the predominant isomers are cis9, trans11 (c9,t11) and trans10, cis12 (t10,c12) CLA. We have previously shown that t10,c12 CLA prevents lipid accumulation in mature adipocytes in part by acting as a peroxisome proliferator-activated receptor gamma (PPAR gamma) modulator. The objective of this study was to further establish the molecular mechanisms underlying the attenuating effect on lipid accumulation by t10,c12 CLA, with focus on time point and duration of treatment during adipogenesis. We have shown that t10,c12 CLA treatment has its most attenuating effect early (day (D) 0-6) during differentiation. Treatment during this period is sufficient to prevent lipid accumulation in mature adipocytes. The adipogenic marker genes PPAR gamma and CCAAT/enhancer binding protein alpha (C/EBP alpha) are both down-regulated after treatment within the period from D0-6, while additional treatment also down-regulates the expression of sterol regulatory element binding protein-1c (SREBP-1c), liver X receptor alpha (LXR alpha), fatty acid binding protein (aP2), fatty acid translocase (CD36) and insulin-sensitive glucose transporter 4 (GLUT4). These effects of t10,c12 CLA reflect the subsequent attenuation of lipid accumulation observed in mature adipocytes. Interestingly, the early B-cell factor (O/E-1), which is known to promote adipogenesis and to be involved in control of genes important for terminal adipocyte differentiation, is unaffected by treatment of t10,c12 CLA. Taken together, our data indicate that inhibition of lipid accumulation induced by t10,c12 CLA treatment during adipocyte differentiation is associated with a tight regulatory cross-talk between early (PPAR gamma and C/EBP alpha) and late (LXR alpha, aP2 and CD36) adipogenic marker genes.     

Selective production of cis-9,trans-11 isomer of conjugated linoleic acid from trans-vaccenic acid methyl ester by Delacroixia coronata

Aims:  Bio-process development for isomer selective and efficient production of cis -9, trans -11-octadecadienoic acid (CLA) from trans -vaccenic acid ( t -VA, trans -11-octadecenoic acid) through microbial fatty acid Δ9-desaturation reaction.
Methods and Results:  A total of 550 strains of fungi and yeasts were screened for CLA production from t -VA through Δ9 desaturation. Delacroixia coronata IFO 8586 was selected as a potent producer of CLA from t -VA. Efficient CLA production was observed during cultivation in medium supplemented with the methyl ester of t -VA ( t -VAME). Under the optimal conditions with 33·3 mg ml⁻¹ of t -VAME as substrate, 10·5 mg ml⁻¹ CLA was produced by D. coronata IFO 8586 after 7 days of cultivation in the medium containing dextrin (5·0%), tryptone (2·0%) and thiourea (0·83 μmol ml⁻¹). The strain produced the cis -9, trans -11 isomer of CLA selectively (98% of total CLA), with a small amount of the trans -9, trans -11 isomer (2% of total CLA), mainly in the form of triacylglycerols (69% of total CLA).
Conclusions:  A practical bio-process for selective production of cis -9, trans -11 isomer of CLA using filamentous fungus D. coronata IFO 8586 was successfully established.
Significance and Impact of the Study:  Isomer selective bio-process for the practical production of cis -9, trans -11-CLA was first established. The process is benefitable for expanding the application of CLA for medicinal and nutraceutical purposes.