Publications

• Cloning of a cDNA encoding diacylglycerol acyltransferase from Arabidopsis thaliana and its functional expression.

  Hobbs D.H., Lu C., Hills M.J.

  Triacylglycerols are the most important storage lipids in most plants and animals. Acyl-CoA:diacylglycerol acyltransferase (EC 2.3.1.20) catalyzes the final step of the pathway of triacylglycerol synthesis and is the only step which is unique to this process. Diacylglycerol acyltransferase is requ ... >> More

  Triacylglycerols are the most important storage lipids in most plants and animals. Acyl-CoA:diacylglycerol acyltransferase (EC 2.3.1.20) catalyzes the final step of the pathway of triacylglycerol synthesis and is the only step which is unique to this process. Diacylglycerol acyltransferase is required for the synthesis of storage oil in a wide range of oil-bearing seeds and fruits and in floral structures such as petals, anthers and pollen. We describe the first cloning and functional expression of a cDNA encoding diacylglycerol acyltransferase from a plant. The cDNA, cloned from Arabidopsis thaliana, encodes a 520 amino acid protein with a predicted molecular mass of 59.0 kDa which shares 38% amino acid sequence identity with diacylglycerol acyltransferase from mouse. When expressed in insect cell cultures, the protein catalyzes the synthesis of [14C]triacylglycerol from [14C]diacylglycerol and acyl-CoA. Primer extension analysis revealed that the transcription begins 225 bases before the translation start site, yielding an unusually long 5' untranslated region. The gene is expressed in a wide range of tissues but most strongly in developing embryos and petals of flowers. << Less

  FEBS Lett. 452:145-149(1999) [PubMed] [EuropePMC]

• Identification of two novel human Acyl-CoA wax alcohol acyltransferases: members of the diacylglycerol acyltransferase 2 (DGAT2) gene superfamily.

  Turkish A.R., Henneberry A.L., Cromley D., Padamsee M., Oelkers P., Bazzi H., Christiano A.M., Billheimer J.T., Sturley S.L.

  The esterification of alcohols such as sterols, diacylglycerols, and monoacylglycerols with fatty acids represents the formation of both storage and cytoprotective molecules. Conversely, the overproduction of these molecules is associated with several disease pathologies, including atherosclerosis ... >> More

  The esterification of alcohols such as sterols, diacylglycerols, and monoacylglycerols with fatty acids represents the formation of both storage and cytoprotective molecules. Conversely, the overproduction of these molecules is associated with several disease pathologies, including atherosclerosis and obesity. The human acyl-CoA:diacylglycerol acyltransferase (DGAT) 2 gene superfamily comprises seven members, four of which have been previously implicated in the synthesis of di- or triacylglycerol. The remaining 3 members comprise an X-linked locus and have not been characterized. We describe here the expression of DGAT2 and the three X-linked genes in Saccharomyces cerevisiae strains virtually devoid of neutral lipids. All four gene products mediate the synthesis of triacylglycerol; however, two of the X-linked genes act as acyl-CoA wax alcohol acyltransferases (AWAT 1 and 2) that predominantly esterify long chain (wax) alcohols with acyl-CoA-derived fatty acids to produce wax esters. AWAT1 and AWAT2 have very distinct substrate preferences in terms of alcohol chain length and fatty acyl saturation. The enzymes are expressed in many human tissues but predominate in skin. In situ hybridizations demonstrate a differentiation-specific expression pattern within the human sebaceous gland for the two AWAT genes, consistent with a significant role in the composition of sebum. << Less

  J. Biol. Chem. 280:14755-14764(2005) [PubMed] [EuropePMC]

  This publication is cited by 9 other entries.

• Acylation of acylglycerols by acyl coenzyme A:diacylglycerol acyltransferase 1 (DGAT1). Functional importance of DGAT1 in the intestinal fat absorption.

  Cheng D., Iqbal J., Devenny J., Chu C.H., Chen L., Dong J., Seethala R., Keim W.J., Azzara A.V., Lawrence R.M., Pelleymounter M.A., Hussain M.M.

  Acyl coenzyme A:diacylglycerol acyltransferase 1 (DGAT1) is one of the four intestinal membrane bound acyltransferases implicated in dietary fat absorption. Recently, it was found that, in addition to acylating diacylglycerol (DAG), DGAT1 also possesses robust enzymatic activity for acylating mono ... >> More

  Acyl coenzyme A:diacylglycerol acyltransferase 1 (DGAT1) is one of the four intestinal membrane bound acyltransferases implicated in dietary fat absorption. Recently, it was found that, in addition to acylating diacylglycerol (DAG), DGAT1 also possesses robust enzymatic activity for acylating monoacylglycerol (MAG) (Yen, C. L., Monetti, M., Burri, B. J., and Farese, R. V., Jr. (2005) J. Lipid Res. 46, 1502-1511). In the current paper, we have conducted a detailed characterization of this reaction in test tube, intact cell culture, and animal models. Enzymatically, we found that triacylglycerol (TAG) synthesis from MAG by DGAT1 does not behave according to classic Michaelis-Menten kinetics. At low concentrations of 2-MAG (<50 microm), the major acylation product by DGAT1 was TAG; however, increased concentrations of 2-MAG (50-200 microm) resulted in decreased TAG formation. This unique product/substrate relationship is similar to MGAT3 but distinct from DGAT2 and MGAT2. We have also found that XP620 is an inhibitor that selectively inhibits the acylation of MAG by DGAT1 (IC(50) of human DGAT1: 16.6+/-4.0 nM (MAG as substrate) and 1499+/-318 nM (DAG as substrate); IC(50) values of human DGAT2, MGAT2, and MGAT3 are >30,000 nM). Using this pharmacological tool, we have shown that approximately 76 and approximately 89% of the in vitro TAG synthesis initiated from MAG is mediated by DGAT1 in Caco-2 cell and rat intestinal mucosal membranes, respectively. When applied to intact cultured cells, XP620 substantially decreased but did not abolish apoB secretion in differentiated Caco-2 cells. It also decreased TAG and DAG syntheses in primary enterocytes. Last, when delivered orally to rats, XP620 decreased absorption of orally administered lipids by approximately 50%. Based on these data, we conclude that the acylation of acylglycerols by DGAT1 is important for dietary fat absorption in the intestine. << Less

  J. Biol. Chem. 283:29802-29811(2008) [PubMed] [EuropePMC]

  This publication is cited by 1 other entry.

• Studies on the substrate and stereo/regioselectivity of adipose triglyceride lipase, hormone-sensitive lipase, and diacylglycerol-O-acyltransferases.

  Eichmann T.O., Kumari M., Haas J.T., Farese R.V. Jr., Zimmermann R., Lass A., Zechner R.

  Adipose triglyceride lipase (ATGL) is rate-limiting for the initial step of triacylglycerol (TAG) hydrolysis, generating diacylglycerol (DAG) and fatty acids. DAG exists in three stereochemical isoforms. Here we show that ATGL exhibits a strong preference for the hydrolysis of long-chain fatty aci ... >> More

  Adipose triglyceride lipase (ATGL) is rate-limiting for the initial step of triacylglycerol (TAG) hydrolysis, generating diacylglycerol (DAG) and fatty acids. DAG exists in three stereochemical isoforms. Here we show that ATGL exhibits a strong preference for the hydrolysis of long-chain fatty acid esters at the sn-2 position of the glycerol backbone. The selectivity of ATGL broadens to the sn-1 position upon stimulation of the enzyme by its co-activator CGI-58. sn-1,3 DAG is the preferred substrate for the consecutive hydrolysis by hormone-sensitive lipase. Interestingly, diacylglycerol-O-acyltransferase 2, present at the endoplasmic reticulum and on lipid droplets, preferentially esterifies sn-1,3 DAG. This suggests that ATGL and diacylglycerol-O-acyltransferase 2 act coordinately in the hydrolysis/re-esterification cycle of TAGs on lipid droplets. Because ATGL preferentially generates sn-1,3 and sn-2,3, it suggests that TAG-derived DAG cannot directly enter phospholipid synthesis or activate protein kinase C without prior isomerization. << Less

  J. Biol. Chem. 287:41446-41457(2012) [PubMed] [EuropePMC]

  This publication is cited by 28 other entries.

• Identification and validation of a selective small molecule inhibitor targeting the diacylglycerol acyltransferase 2 activity.

  Kim M.O., Lee S.U., Lee H.J., Choi K., Kim H., Lee S., Oh S.J., Kim S., Kang J.S., Lee H.S., Kwak Y.S., Cho S.

  Diacylglycerol acyltransferase 2 (DGAT2) is one of two distinct DGAT enzymes that catalyze the last step in triacylglycerol (TG) synthesis. Findings from previous studies suggest that inhibition of DGAT2 is a promising strategy for the treatment of hepatic steatosis and insulin resistance. Here, w ... >> More

  Diacylglycerol acyltransferase 2 (DGAT2) is one of two distinct DGAT enzymes that catalyze the last step in triacylglycerol (TG) synthesis. Findings from previous studies suggest that inhibition of DGAT2 is a promising strategy for the treatment of hepatic steatosis and insulin resistance. Here, we identified compound 122 as a potent and selective inhibitor of human DGAT2, which appeared to act competitively against oleoyl-CoA in vitro. The selective inhibition of DGAT2 was also confirmed by the reductions in enzymatic activity and de novo TG synthesis in DGAT2-overexpressing HEK293 cells and hepatic cells HepG2. Compound 122, as a newly identified inhibitor of DGAT2, will be useful for the research on DGAT2-related lipid metabolism as well as the development of therapeutic drug for several metabolic diseases. << Less

  Biol Pharm Bull 36:1167-1173(2013) [PubMed] [EuropePMC]

• Synthesis of a novel acetylated neutral lipid related to platelet-activating factor by acyl-CoA:1-O-alkyl-2-acetyl-sn-glycerol acyltransferase in HL-60 cells.

  Kawasaki T., Snyder F.

  Acyl-CoA:1-O-hexadecyl-2-acetyl-sn-glycerol acyl-transferase, a newly detected enzyme related to platelet-activating factor metabolism, has been characterized in microsomes of a human leukemia cell line (HL-60 cells). It has a sharp pH optimum of 6.8, does not require divalent metal ions, is stabl ... >> More

  Acyl-CoA:1-O-hexadecyl-2-acetyl-sn-glycerol acyl-transferase, a newly detected enzyme related to platelet-activating factor metabolism, has been characterized in microsomes of a human leukemia cell line (HL-60 cells). It has a sharp pH optimum of 6.8, does not require divalent metal ions, is stable at preincubation temperatures up to 45 degrees C, and among a variety of acyl-CoA thioesters (8:0-20:4) tested, linoleoyl-CoA is the best substrate. Km and Vmax values for 1-O-hexadecyl-2-acetyl-sn-glycerol acyltransferase are 8.5 microM and 1.7 nmol/min/mg of protein, respectively. For comparative purposes acyl-CoA:1,2-dioleoyl-sn-glycerol acyltransferase was also characterized in HL-60 microsomes. It has a relatively broad pH optimum of 6.1, is stimulated 1.4-fold by Mg2+, is relatively labile at preincubation temperatures higher than 25 degrees C, and among the various acyl-CoA thioesters tested, myristoyl-CoA is the best substrate. In substrate competition experiments, we found 1-O-hexadecyl-2-oleoyl-sn-glycerol is a competitive inhibitor (Ki = 32 microM). Our findings indicate acyl-CoA:1-O-hexadecyl-2-acetyl-sn-glycerol acyltransferase in HL-60 cells is distinctly different from acyl-CoA:1,2-dioleoyl-sn-glycerol acyltransferase. Our experimental results demonstrate that the unique enzyme activity characterized in this report also is expressed in intact HL-60 cells. << Less

  J Biol Chem 263:2593-2596(1988) [PubMed] [EuropePMC]

  This publication is cited by 14 other entries.