Articles

After development, adult skeletal muscle retains the capacity to regenerate by activating muscle stem cells. Here the authors demonstrate that the glycosylphosphatidylinositol-anchored membrane protein GAS1, which is induced in muscle stem cells with age, suppresses muscle regenerative capacity but can be inhibited by glial cell line-derived neurotrophic factor (GDNF).

The liver is a heterogeneous organ organized in lobules that are radially polarized. The use of single-cell spatial transcriptomics has revealed that half of hepatic genes are differentially expressed across the lobule. Ben-Moshe et al. show how a multi-omics approach, which consists of transcriptomics, micro RNA profiling and proteomics, allows for characterization of liver heterogeneity with higher resolution.

Tajima and colleagues identify mitochondrial lipoylation as a post-transcriptional molecular signature of aged brown adipose tissue (BAT) in mice. Reduced mitochondrial lipoylation is tightly coupled with the age-associated decline in BAT function, whereas enhanced lipoylation restores BAT activity in aged mice.

Chen et al. report that TGF-β signalling, although largely considered anti-inflammatory, has proinflammatory effects on endothelial cells. Inhibition of endothelial TGF-β signalling decreases atherosclerosis in mice and reverts established plaques, in part by decreasing endothelial-to-mesenchymal transitions.

Some follicular B cell lymphomas harbour activating mutations in RRAGC, activator of the nutrient sensor mTORC1. Here the authors show that these mutations confer insensitivity to nutrient deprivation and synergize with paracrine cues from the supportive T cell microenvironment to accelerate lymphomagenesis, but impose vulnerability to inhibition of mTORC1.

Folgueira et al. show that dopamine signalling in the lateral hypothalamic area and the zona incerta reduces body weight and increases energy expenditure by increasing brown adipose tissue thermogenesis in rodents. Weight loss and increased energy expenditure were also observed in patients treated with a dopamine receptor 2 agonist.

Brown adipose tissue (BAT) has high thermogenic potential and is considered a promising target to counteract obesity. Here de Jong et al. demonstrate that human BAT is more similar to classical brown than to beige adipose tissue from mice kept at thermoneutrality and challenged with a high-fat diet.

Although germline removal normally extends Caenorhabditis elegans lifespan, Lee et al. show that low temperature does not extend lifespan in germline-lacking mutant worms. Cold temperatures (10 °C, 15 °C) delay germline stem cell exhaustion, releasing prostaglandin E2 hormone, which induces cbs-1 in the intestine to produce hydrogen sulfide and prolong lifespan.

Macrophages engage in a sequence of dynamic functional changes during immune responses. Here the authors elucidate a two-stage remodelling of the tricarboxylic acid cycle during this process, which is driven by regulation of the pyruvate dehydrogenase and the oxoglutarate dehydrogenase complexes, and causes transient accumulation of immunoregulatory metabolites.

Spontaneous control of HIV is linked to the ability of CD8⁺ T cells to eliminate infected CD4⁺ T cells. Here, the authors uncover metabolic differences between HIV-specific, central memory CD8⁺ T cells from spontaneous HIV controllers and antiretrovirally treated non-controllers, and show that in vitro metabolic reprogramming enhances the antiviral response in non-controllers cells.

Increased metabolic activity promotes HIV-1 infection in CD4 T lymphocytes, but the contribution of different metabolic pathways is unclear. Here the authors show that carbon entry into the citric acid cycle is required to support the early stages of HIV-1 infection.

Non-coding RNAs are important regulators of several biological processes, including metabolic functions. Here Arcinas and colleagues demonstrate that circular RNAs, a class of non-coding RNAs, are widely expressed in adipose tissue and display dynamic regulation during adipogenesis and obesity.

Non-alcoholic steatosis is characterized by lipid accumulation within hepatocytes and can progress to NASH. Haas and colleagues demonstrate that livers from people with NASH show a distinct but reversible gene profile from simple steatosis and accumulation of intrahepatic cDC and CD8 T cells.

In this study, the authors use ATAC-seq and promoter capture Hi-C data from human adipocytes treated with fatty acids to identify gene–environment (G×E) interactions that influence body-mass index in humans. They report 154 genes that respond to saturated fat and discover 38 new G×E variants for body-mass index in data from the UK Biobank.

Bioproduct synthesis via reductive metabolism occurs with different efficiencies according to the availability of carbons, ATP and reducing agents. To maximize overall product synthesis efficiency, the authors develop a substrate cofeeding strategy, which circumvents catabolite repression and drives synergy in lipid synthesis from CO₂ using two microbes.

Pancreatic β-cells are highly connected, and this network is crucial for the pulsatile release of insulin. Here Salem and colleagues demonstrated the existence of leader β-cells that respond first to glucose and are more closely linked to the other β-cells. They also showed that glucose increases β-cell calcium dynamics and connectivity between the leader and non-leader β-cells.

Iron homoeostasis is tightly orchestrated to avoid toxic iron overload. Here Lim and colleagues show that iron excess activates Nrf2 via mitochondrial reactive oxygen species, enhancing the expression of Bmp6 in liver sinusoidal endothelial cells, which in turn promotes hepcidin expression by hepatocytes, decreasing systemic iron levels.

Metabolism is tightly regulated through communication among cells and organs. Here Gong and colleagues show that a liver-secreted factor, Gpnmb, promotes lipogenesis in adipose tissue and worsens metabolic dysfunctions during diet-induced obesity, whereas its inhibition reduces weight gain and insulin resistance.

Here the authors demonstrate a mechanism by which PNPLA3 and its risk variant I148M contribute to intracellular lipid metabolism. PNPLA3 interacts with ABHD5 to prevent the PNPLA2–ABHD5 interaction, thereby inhibiting lipolysis in brown adipocytes and promoting lipid storage. The PNPLA3 I148M variant enhances this interaction.

Dietary protein influences metabolic health and ageing. Here Solon-Biet et al. show that, rather than having a direct toxic effect, dietary branched-chain amino acids (BCAAs) appear to induce hyperphagia, owing to an imbalance between BCAAs and other amino acids, which reduces lifespan as a consequence of obesity.