title: Impaired lipid accumulation by trans10, cis12 CLA during adipocyte differentiation is dependent on timing and length of treatment.
abstract: 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.
authors.affiliation: Institute of Basic Medical Sciences, Department of Nutrition, University of Oslo, N-0316 Oslo, Norway.
authors.forename: Linda
authors.initials: L
authors.lastname: Granlund
authors.forename: Jan I
authors.initials: JI
authors.lastname: Pedersen
authors.forename: Hilde I
authors.initials: HI
authors.lastname: Nebb
mesh_terms: D016475:3T3 Cells; D017667:Adipocytes / Q000166:cytology / Q000187:drug effects* / Q000502:physiology*; D000818:Animals; D022763:CCAAT-Enhancer-Binding Protein-alpha / Q000235:genetics / Q000378:metabolism; D022762:CCAAT-Enhancer-Binding Proteins / Q000235:genetics / Q000378:metabolism; D018955:CD36 Antigens / Q000235:genetics / Q000378:metabolism; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism; D002454:Cell Differentiation / Q000502:physiology*; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D050556:Fatty Acid-Binding Proteins; D018507:Gene Expression Regulation, Developmental; D051275:Glucose Transporter Type 4; D006801:Humans; D044243:Linoleic Acids, Conjugated / Q000494:pharmacology*; D050356:Lipid Metabolism; D000071518:Liver X Receptors; D051379:Mice; D009004:Monosaccharide Transport Proteins / Q000235:genetics / Q000378:metabolism; D009124:Muscle Proteins / Q000235:genetics / Q000378:metabolism; D057093:Orphan Nuclear Receptors; D047495:PPAR gamma / Q000235:genetics / Q000378:metabolism; D018160:Receptors, Cytoplasmic and Nuclear / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction / Q000502:physiology; D051780:Sterol Regulatory Element Binding Protein 1; D013997:Time Factors; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism
chemical_list: D022763:CCAAT-Enhancer-Binding Protein-alpha; D022762:CCAAT-Enhancer-Binding Proteins; D018955:CD36 Antigens; D002352:Carrier Proteins; D004268:DNA-Binding Proteins; D050556:Fatty Acid-Binding Proteins; D051275:Glucose Transporter Type 4; D044243:Linoleic Acids, Conjugated; D000071518:Liver X Receptors; D009004:Monosaccharide Transport Proteins; D009124:Muscle Proteins; C000605213:NR1H3 protein, human; C000605214:Nr1h3 protein, mouse; D057093:Orphan Nuclear Receptors; D047495:PPAR gamma; D018160:Receptors, Cytoplasmic and Nuclear; C495692:SLC2A4 protein, human; C497387:SREBF1 protein, human; C495693:Slc2a4 protein, mouse; C497388:Srebf1 protein, mouse; D051780:Sterol Regulatory Element Binding Protein 1; D014157:Transcription Factors; C496197:trans-10,cis-12-conjugated linoleic acid