Long-chain acyl-CoA synthetase regulates systemic lipid homeostasis via glycosylation-dependent lipoprotein production

Elucidating a novel metabolic pathway for enhanced antimicrobial glycolipid biosurfactant production in the yeast Meyerozyma guilliermondii

Biosurfactants offer good advantages over synthetic counterparts, including biodegradability, environmentally friendly and low toxicity. This study employed a yeast Meyerozyma guilliermondii MX strain for bioconversion of lignocellulosic xylose and palm oil to valuable glycolipid biosurfactant with desirable properties. The objective was to elucidate metabolic pathways related to production of glycolipids and its functional properties. To enhance de novo glycolipid production, manipulation of responsible enzymatic genes was conducted using media and environmental means in comparison to the industrial glycolipid producer, Candida bombicola. Proteomic profiles of yeast cells grown with or without palm oil uncovered novel key metabolic enzymes, namely fatty acid biosynthetic enzymes, leading to formation of glycolipid precursors. qRT-PCR identified some cluster genes responsible for biosynthesis of desirable glycolipids. Finally, LC-MS-based lipidomics of glycolipid fraction identified 15-(2'-O-β-D-glucopyranosyl-β-D-glucopyranosyloxy)hexadecanoic acid 1',4″-lactone 6',6″-diacetate (663.4525 m/z) as a major product. Using co-carbon substrates in the presence of salt and zinc, maximum glycolipid yield was achieved (55.72 g/L) with 55.30% emulsification activity and 10 mg/L of CMCs. Mixed glycolipids demonstrated antibiofilm activity against Candida albicans shown by reduction of metabolic activity. The novel biosurfactant-producing yeast M. guilliermondii MX is a promising cell factory of new antibiofilm glycolipids with potential for industrial-scale up.

The circadian clock at the intersection of metabolism and aging - emerging roles of metabolites

The circadian clock is a highly hierarchical network of endogenous pacemakers that primarily maintains and directs oscillations through transcriptional and translational feedback loops, which modulates an approximately 24-hour cycle of endocrine and metabolic rhythms within cells and tissues. While circadian clocks regulate metabolic processes and related physiology, emerging evidence indicates that metabolism and circadian rhythm are intimately intertwined. In this review, we highlight the concept of metabolites, including lipids and other polar metabolites generated from intestinal microbial metabolism and nutrient intake, as circadian pacemakers that drive changes in circadian rhythms, which in turn influence metabolism and aging. Furthermore, we discuss the roles of functional metabolites as circadian pacemakers, paving a new direction on potential intervention targets of circadian disruption, pathological aging, as well as metabolic diseases that are clinically important.

Branched-chain amino acid catabolism promotes M2 macrophage polarization

Introduction

During an immune response, macrophages undergo systematic metabolic rewiring tailored to support their functions. Branched-chain amino acid (BCAA) metabolism has been reported to modulate macrophage function; however, its role in macrophage alternative activation remain unclear. We aimed to investigate the role of BCAA metabolism in macrophage alternative activation.

Method

The metabolomics of BMDM-derived M0 and M2 macrophages were analyzed using LC-MS. BCAAs were supplemented and genes involved in BCAA catabolism were inhibited during M2 macrophage polarization. The expression of M2 marker genes was assessed through RT-qPCR, immunofluorescence, and flow cytometry.

Results and discussion

Metabolomic analysis identified increased BCAA metabolism as one of the most significantly rewired pathways upon alternative activation. M2 macrophages had significantly lower BCAA levels compared to controls. BCAA supplementation promoted M2 macrophage polarization both in vitro and in vivo and increased oxidative phosphorylation in M2 macrophages. Blocking BCAA entry into mitochondria by knockdown of SLC25A44 inhibited M2 macrophage polarization. Furthermore, M2 macrophages polarization was suppressed by knockdown of Branched-chain amino-acid transaminase 2 (BCAT2) and branched chain keto acid dehydrogenase E1 subunit alpha (BCKDHA), both of which are key enzymes involved in BCAA oxidation. Overall, our findings suggest that BCAA catabolism plays an important role in polarization toward M2 macrophages.