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Diacylglycerol acyltransferase 2 links glucose utilization to fatty acid oxidation in the brown adipocytes.

ABSTRACT: Brown adipose tissue uptake of glucose and fatty acids is very high during nonshivering thermogenesis. Adrenergic stimulation markedly increases glucose uptake, de novo lipogenesis, and FA oxidation simultaneously. The mechanism that enables this concerted response has hitherto been unknown. Here, we find that in primary brown adipocytes and brown adipocyte-derived cell line (IMBAT-1), acute inhibition and longer-term knockdown of DGAT2 links the increased de novo synthesis of fatty acids from glucose to a pool of TAG that is simultaneously hydrolyzed, providing FA for mitochondrial oxidation. DGAT1 does not contribute to this pathway, but uses exogenous FA and glycerol to synthesize a functionally distinct pool of TAG to which DGAT2 also contributes. The DGAT2-dependent channelling of 14C from glucose into TAG and CO2 was reproduced in ?3-agonist-stimulated primary brown adipocytes. Knockdown of DGAT2 in IMBAT-1 affected the mRNA levels of UCP1 and genes important in FA activation and esterification. Therefore, in ?3-agonist activated brown adipocytes, DGAT2 specifically enables channelling of de novo synthesized FA into a rapidly mobilized pool of TAG, which is simultaneously hydrolyzed to provide substrates for mitochondrial fatty acid oxidation.

SUBMITTER: Irshad Z

PROVIDER: S-EPMC5234708 | biostudies-other | 2017 Jan

REPOSITORIES: biostudies-other

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Diacylglycerol acyltransferase 2 links glucose utilization to fatty acid oxidation in the brown adipocytes.

Irshad Zehra Z Dimitri Federica F Christian Mark M Zammit Victor A VA

Journal of lipid research 20161111 1

Brown adipose tissue uptake of glucose and fatty acids is very high during nonshivering thermogenesis. Adrenergic stimulation markedly increases glucose uptake, de novo lipogenesis, and FA oxidation simultaneously. The mechanism that enables this concerted response has hitherto been unknown. Here, we find that in primary brown adipocytes and brown adipocyte-derived cell line (IMBAT-1), acute inhibition and longer-term knockdown of DGAT2 links the increased de novo synthesis of fatty acids from g ...[more]

PMID: 27836993

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Project description:Claviceps purpurea, the fungal pathogen that causes the cereal disease ergot, produces glycerides that contain high levels of ricinoleic acid [(R)-12-hydroxyoctadec-cis-9-enoic acid] in its sclerotia. Recently, a fatty acid hydroxylase (C. purpurea FAH [CpFAH]) involved in the biosynthesis of ricinoleic acid was identified from this fungus (D. Meesapyodsuk and X. Qiu, Plant Physiol. 147:1325-1333, 2008). Here, we describe the cloning and biochemical characterization of a C. purpurea type II diacylglycerol acyltransferase (CpDGAT2) involved in the assembly of ricinoleic acid into triglycerides. The CpDGAT2 gene was cloned by degenerate RT-PCR (reverse transcription-PCR). The expression of this gene restored the in vivo synthesis of triacylglycerol (TAG) in the quadruple mutant strain Saccharomyces cerevisiae H1246, in which all four TAG biosynthesis genes (DGA1, LRO1, ARE1, and ARE2) are disrupted. In vitro enzymatic assays using microsomal preparations from the transformed yeast strain indicated that CpDGAT2 prefers ricinoleic acid as an acyl donor over linoleic acid, oleic acid, or linolenic acid, and it prefers 1,2-dioleoyl-sn-glycerol over 1,2-dipalmitoyl-sn-glycerol as an acyl acceptor. The coexpression of CpFAH with CpDGAT2 in yeast resulted in an increased accumulation of ricinoleic acid compared to the coexpression of CpFAH with the native yeast DGAT2 (S. cerevisiae DGA1 [ScDGA1]) or the expression of CpFAH alone. Northern blot analysis indicated that CpFAH is expressed solely in sclerotium cells, with no transcripts of this gene being detected in mycelium or conidial cells. CpDGAT2 was more widely expressed among the cell types examined, although expression was low in conidiospores. The high expression of CpDGAT2 and CpFAH in sclerotium cells, where high levels of ricinoleate glycerides accumulate, provided further evidence supporting the roles of CpDGAT2 and CpFAH as key enzymes for the synthesis and assembly of ricinoleic acid in C. purpurea.

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Diacylglycerol acyltransferase 2 links glucose utilization to fatty acid oxidation in the brown adipocytes.

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Diacylglycerol acyltransferase 2 links glucose utilization to fatty acid oxidation in the brown adipocytes.

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