Disease relevance of MOGAT1

• The discovery of the MGAT2 gene will facilitate studies to determine the functional role of MGAT2 in fat absorption in the intestine and to determine whether blocking MGAT activity in enterocytes is a feasible approach to inhibit fat absorption and treat obesity [1].
• In order to study the regulation of MGAT, we developed a rapid assay that can be performed directly on permeabilized HA rat hepatocyte/hepatoma hybrid cells, a line that expresses levels of hepatic MGAT activity and a lipogenic program characteristic of fetal hepatocytes [2].

High impact information on MOGAT1

• Acyl CoA:monoacylglycerol acyltransferase (MGAT) catalyzes the synthesis of diacylglycerol, a precursor of triacylglycerol [1].
• In the intestine, MGAT plays a major role in the absorption of dietary fat by catalyzing the resynthesis of triacylglycerol in enterocytes [1].
• Although the mouse small intestine exhibits the highest MGAT enzyme activity among all of the tissues studied, the gene encoding the enzyme has not been identified so far [3].
• Expression of the MGAT2 cDNA in either insect or mammalian cells markedly increased MGAT activity in cell membranes [1].
• We also analyzed the biochemical features of MGAT2 and demonstrated homogenate protein-, time-, and substrate concentration-dependent MGAT enzyme activity in transiently transfected COS-7 cells [3].

Biological context of MOGAT1

• In MOGAT1, a missense mutation in exon 4 was found that causes a non-conservative substitution of cysteine170 (uncharged, hydrophobic) by lysine (positively charged, hydrophilic) [4].
• The pH optimum of MGAT activity was 7.0, and the dependence of the activity on the concentration of 2-monoolein showed saturation kinetics [5].
• Previous results from this laboratory suggested that the hydrolysis of stored triacylglycerol to sn-2-monoacylglycerol followed by the stereospecific acylation of sn-2-monoacylglycerol catalyzed by a monoacylglycerol-acyltransferase (MGAT) could be the major route of AKH-stimulated sn-1,2-diacylglycerol synthesis [5].
• MGAT activity increased directly with cell density and was unrelated to the number of days in culture [2].
• Although the changes were consistent with active year-round triacylglycerol synthesis, the higher summer MGAT activity observed in the squirrel liver and WAT suggest that MGATs function may not be limited to conserving essential fatty acids during physiological states of lipolysis [6].

Anatomical context of MOGAT1

• Previously, we identified a gene encoding MGAT1, which in mice is expressed in the stomach, kidney, adipose tissue, and liver but not in the intestine [1].
• Despite a significant level of hMGAT2 mRNA in the human liver, little MGAT activity was detected in liver microsomes when tested against monoacyglcerols with different unsaturated side chains, suggesting possible posttranscriptional regulation [7].
• In this study we characterized the MGAT activity from the Manduca sexta fat body [5].

Associations of MOGAT1 with chemical compounds

• AKH did not stimulate MGAT activity, suggesting that either the enzyme is not under hormonal regulation or the monoacylglycerol pathway is not involved in the AKH-stimulated production of sn-1,2-diacylglycerol in the M. sexta fat body [5].
• Activity was low with the 1(3)- and sn-2-ether analogs of monooleoylglycerol, supporting the conclusion that the cells express the hepatic isoenzyme of MGAT [2].
• In permeabilized HA cells, MGAT activity was proportional to the time of incubation and was highly dependent on added sn-2-monoacylglycerol and palmitoyl-CoA [2].
• Long-term incubation (2-4 days) of HA cells with various hormones (including triiodothyronine, human placental lactogen, epidermal growth factor, glucagon and growth hormone) showed that only a combination of dexamethasome and insulin resulted in significantly decreased MGAT activity [2].

Other interactions of MOGAT1

• We report the cloning and initial characterization of the genes encoding DGAT2 (diacylglycerol transferase 2), MOGAT1 and MOGAT2 (monoacylglycerol transferases 1 and 2) in domestic cattle (Bos taurus) [4].
• Genomic organization of the DGAT2/MOGAT gene family in cattle (Bos taurus) and other mammals [4].

References