Identification of an alternative triglyceride biosynthesis pathway

McLelland, Gian-Luca and Lopez-Osias, Marta and Verzijl, Cristy R. C. and Ellenbroek, Brecht D. and Oliveira, Rafaela A. and Boon, Nicolaas J. and Dekker, Marleen and van den Hengel, Lisa G. and Ali, Rahmen and Janssen, Hans and Song, Ji-Ying and Krimpenfort, Paul and van Zutphen, Tim and Jonker, Johan W. and Brummelkamp, Thijn R. (2023) Identification of an alternative triglyceride biosynthesis pathway. Nature, 621 (7977). pp. 171-178. ISSN 0028-0836

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Abstract

Triacylglycerols (TAGs) are the main source of stored energy in the body, providing an important substrate pool for mitochondrial beta-oxidation. Imbalances in the amount of TAGs are associated with obesity, cardiac disease and various other pathologies1,2. In humans, TAGs are synthesized from excess, coenzyme A-conjugated fatty acids by diacylglycerol O-acyltransferases (DGAT1 and DGAT2)3. In other organisms, this activity is complemented by additional enzymes4, but whether such alternative pathways exist in humans remains unknown. Here we disrupt the DGAT pathway in haploid human cells and use iterative genetics to reveal an unrelated TAG-synthesizing system composed of a protein we called DIESL (also known as TMEM68, an acyltransferase of previously unknown function) and its regulator TMX1. Mechanistically, TMX1 binds to and controls DIESL at the endoplasmic reticulum, and loss of TMX1 leads to the unconstrained formation of DIESL-dependent lipid droplets. DIESL is an autonomous TAG synthase, and expression of human DIESL in Escherichia coli endows this organism with the ability to synthesize TAG. Although both DIESL and the DGATs function as diacylglycerol acyltransferases, they contribute to the cellular TAG pool under specific conditions. Functionally, DIESL synthesizes TAG at the expense of membrane phospholipids and maintains mitochondrial function during periods of extracellular lipid starvation. In mice, DIESL deficiency impedes rapid postnatal growth and affects energy homeostasis during changes in nutrient availability. We have therefore identified an alternative TAG biosynthetic pathway driven by DIESL under potent control by TMX1.

Item Type: Article
Subjects: Archive Digital > Multidisciplinary
Depositing User: Unnamed user with email support@archivedigit.com
Date Deposited: 14 Nov 2023 07:49
Last Modified: 14 Nov 2023 07:49
URI: http://eprints.ditdo.in/id/eprint/1681

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