ACSS2-mediated acetyl-CoA synthesis from acetate is necessary for human cytomegalovirus infection

Abstract

Recent studies have shown that human cytomegalovirus (HCMV) can induce a robust increase in lipid synthesis which is critical for the success of infection. In mammalian cells the central precursor for lipid biosynthesis, cytosolic acetyl CoA (Ac-CoA), is produced by ATPcitrate lyase (ACLY) from mitochondria-derived citrate or by acetylCoA synthetase short-chain family member 2 (ACSS2) from acetate. It has been reported that ACLY is the primary enzyme involved in making cytosolic Ac-CoA in cells with abundant nutrients. However, using CRISPR/Cas9 technology, we have shown that ACLY is not essential for HCMV growth and virally induced lipogenesis. Instead, we found that in HCMV-infected cells glucose carbon can be used for lipid synthesis by both ACLY and ACSS2 reactions. Further, the ACSS2 reaction can compensate for the loss of ACLY. However, in ACSS2-KO human fibroblasts both HCMV-induced lipogenesis from glucose and viral growth were sharply reduced. This reduction suggests that glucose-derived acetate is being used to synthesize cytosolic Ac-CoA by ACSS2. Previous studies have not established a mechanism for the production of acetate directly from glucose metabolism. Here we show that HCMV-infected cells produce more glucose-derived pyruvate, which can be converted to acetate through a nonenzymatic mechanism.human cytomegalovirus | ACLY | ACSS2 | acetate | Acetyl-CoA

De novo acetate production is coupled to central carbon metabolism in mammals

“…We then employed LC-HRMS to enable spectral resolution of [ 18 O 1 ]-acetate from other isotopically labeled species. Analysis of the incorporation of 18 O into tryptophan-related metabolites that are produced through oxygenation and stable labeling after 48 hrs demonstrated that 45% of the total O 2 is 18 O labeled in this setup (Fig. 2c).…”

“…2a top), and the reaction would involve incorporation of the oxygen into H 2 O 2 via production of superoxides and then into acetate. H 2 O 2 thus obtains oxygen from molecular O 2 and therefore, culturing cells in the presence of 18 O 2 and monitoring incorporation of 18 O into peer-reviewed) is the author/funder. All rights reserved.…”

“…No reuse allowed without permission. 18 O 2 , d4-acetaldehyde, d3-sodium acetate, ammonium tetrathiomolybdate (TTM), CPI-613, RPMI 1640 (without sodium bicarbonate), HEPES buffer, pyruvate dehydrogenase and ketoglutarate dehydrogeanse (from porcine heart) were purchased from Sigma. d3-acetyl-carnitine hydrochloride was purchased from Santa Cruz Biotechnology.…”

“…This pathway is essential in nutrient deprived tumor microenvironments and other diverse contexts but the origin of acetate has been unclear [8][9][10][11][12][13][14] . It has been postulated that acetate may be synthesized de novo in cells [15][16][17][18][19] but the pathways and quantitative reaction mechanisms through which this may occur are unknown. Given that alternative carbon sources often arise from overflow metabolism, we suspected that such a mechanism may allow for acetate generation.…”

Recent advances in CMV tropism, latency, and diagnosis during aging

“…Previous system-level examination of metabolites and their fluxes found that HCMV infection resulted in remodeling of carbon metabolism (Chambers et al 2010;Munger et al 2006;Purdy et al 2015;Vastag et al 2011;Hwang et al 2014). The flow of carbons from glucose to fatty acid metabolism is increased, possibly involving the non-enzymatic conversation of a pyruvate to acetate to generate the substrates required for fatty acid synthesis and elongation (Vysochan et al 2017). Likewise, carbons from glutamine are redirected for anaplerotic usage to replenish the TCA cycle (Munger et al 2008;Chambers et al 2010).…”