bims-obesme 2026-07-26 papers

Issue of 2026–07–26
six papers selected by
Xiong Weng, University of Edinburgh

Cell Metab. 2026 Jul 21. pii: S1550-4131(26)00274-3. [Epub ahead of print]

Competitive catabolism drives hyperglycemia and hyperinsulinemia in obesity.

Daniel R Weilandt, Won Dong Lee, Michael R MacArthur, Lingfan Liang, Corey D Holman, Qingwei Chu, Alexis J Cowan, Joseph A Baur, Ned S Wingreen, Joshua D Rabinowitz.

Systemic metabolic homeostasis maintains circulating nutrient concentrations within physiological ranges. Insulin is central to this process, lowering circulating levels of glucose, lactate, free fatty acids, and ketones. Yet how the simultaneous homeostasis of these nutrients is achieved remains unclear. Here, we develop a differential equation model of fasting metabolic homeostasis. Grounded in mass action kinetics, this multi-nutrient model reveals how a fixed energy demand naturally leads to competition between major circulating nutrients for oxidation ("competitive catabolism"). Perturbative nutrient infusions confirm this emergent behavior. The multi-nutrient model predicts that insulin promotes fasting glucose homeostasis primarily indirectly by slowing lipolysis. It further identifies a physiological circuit by which obesity causes insulin resistance: increased fat mass promotes lipolysis, releasing fatty acids into circulation that compete with glucose for oxidation, elevating glucose and thus insulin, which acts to restore proper lipid catabolic flux. Thus, quantitative modeling reveals a physiological homeostatic circuit through which obesity causes type 2 diabetes.

Keywords: competitive catabolism; differential equation modeling; hyperinsulinemia; insulin regulation; insulin resistance; mass action kinetics; metabolic homeostasis; nutrient competition; obesity; type 2 diabetes

DOI: https://doi.org/10.1016/j.cmet.2026.07.001

J Clin Invest. 2026 Jul 23. pii: e207089. [Epub ahead of print]

Palmitic acid coordinates impaired visceral adipose ICOShi Treg-mediated immunosuppression and systemic metabolic disturbance during obesity.

Regulatory T (Treg) cells in visceral adipose tissue (VAT) play essential roles in systemic metabolic homeostasis under distinct physiological and pathological conditions. However, the metabolic cues that drive Treg cell subset specialization in the obese VAT niche remain elusive. Here, we demonstrated that palmitic acid instigated chronic VAT inflammation and systemic metabolic disturbance by compromising the immunosuppressive function of the ICOShi Treg subset. Palmitic acid, but not oleic acid, activated Crebzf expression in VAT Treg cells from HFHS diet-induced obese and ob/ob mice. Crebzf deficiency significantly attenuated diet-induced obesity and inflammation by upregulating the suppressive function of VAT ICOShi Treg cells. Moreover, adoptive transfer of Crebzf-deficient ICOShi Treg cells into Rag1-/- mice alleviated HFHS diet-induced inflammation and metabolic disorders more effectively than transfer of Crebzf-sufficient ICOShi Treg cells. Mechanistically, CREBZF interacted with c-JUN to inhibit Foxp3 activity, thereby impairing the stability and inhibitory cytokine production of ICOShi Treg cells. In human subjects, CREBZF levels in VAT Treg cells were elevated and negatively correlated with FOXP3 activity. Collectively, these findings uncover a specific ICOShi Treg subset that responds to palmitic acid, thereby coupling obesogenic signals to VAT remodeling and systemic metabolic homeostasis.

Keywords: Inflammation; Metabolism; Obesity; T cells

DOI: https://doi.org/10.1172/JCI207089

Nat Rev Genet. 2026 Jul 23.

Human genetics across levels of biological organization.

Diederik S Laman Trip, Pedro Beltrao.

Genetic variation influences human physiology across biological scales from molecules to cells, tissues, organs and the whole organism. Unravelling how variants and their genetic effects propagate across these levels, through molecular interactions, cellular programmes and tissue architectures, to shape phenotypes remains a central challenge in human genetics. Resolving this challenge requires deciphering the genetic architecture of each biological layer and developing systems-level analyses that aim to integrate across scales. Network-based and computational approaches, including artificial intelligence, offer opportunities to move beyond statistical associations towards a context-aware, mechanistic understanding of the genetics underlying human traits and disease, although integration across layers remains limited. Here we review recent advances in mapping genetic effects across biological scales, from intracellular networks that capture molecular interactions, through single-cell and spatial omics approaches that define cellular and tissue contexts, to population-scale imaging genomics that links genetic variation to organ-level and organismal phenotypes. We discuss emerging strategies and remaining challenges for integrating these layers into mechanistic models of genotype-phenotype relationships.

DOI: https://doi.org/10.1038/s41576-026-00991-x

Nat Metab. 2026 Jul 24.

Distinct brain regions mediate regulation of food intake in response to GIPR agonism or antagonism.

Jo Edward Lewis, Mireia Montaner, Danae Nuzzaci, Paula-Peace James-Okoro, Norio Harada, Nobuya Inagaki, W Scott Dodson, Patrick J Knerr, Jonathan D Douros, Fiona Mary Gribble, Frank Reimann.

The development of dual agonists for the glucagon-like peptide-1 receptor (GLP-1R) and glucose-dependent insulinotropic polypeptide receptor (GIPR) has been a landmark moment in the treatment of type 2 diabetes and obesity. However, for reasons that are incompletely understood, in preclinical and clinical studies, adding either a GIPR agonist or GIPR antagonist to GLP-1R agonism causes additional weight loss1. Here we show that distinct brain regions mediate the appetite-suppressing effects of GIPR agonists and the synergistic weight loss effects conferred by GIPR antagonists. We knock out Gipr in either the area postrema (AP) or hypothalamus of mice (GiprAP-KO and Giprhypo-KO, respectively) and compare body weight and food intake responses to GIPR agonists and antagonists, alone and in combination with the GLP-1R agonist liraglutide. GiprAP-KO mice exhibit partial protection against diet-induced obesity, reduced responsiveness to the appetite-suppressing effects of acyl-GIP and a reduced ability of acyl-GIP to prevent avoidance triggered by peptide YY. Weight loss effects of liraglutide are comparable in GiprAP-KO and control mice, and the co-administration of a GIPR antagonist peptide causes similar additional weight loss in both groups. Giprhypo-KO mice, by contrast, exhibit normal appetite suppression by acyl-GIP but enhanced weight loss on liraglutide compared with control mice. Giprhypo-KO also abolishes the synergistic effect of a GIPR antagonist when combined with liraglutide-an effect that is not mediated by nucleus tractus solitarius preproglucagon neurons. GIPR antagonism and Giprhypo-KO also sensitise to cagrilintide-induced weight loss. Overall, our results suggest that the AP is responsible for the appetite-suppressing effects of GIPR agonism but that GIP receptors in the hypothalamus underlie the ability of GIPR antagonism to enhance the weight loss effects of GLP-1R and amylin receptor agonists.

DOI: https://doi.org/10.1038/s42255-026-01575-z

Sci Adv. 2026 Jul 24. 12(30): eaeb0060

Single-cell chromatin state transitions during epigenetic memory formation.

Taihei Fujimori, Abby R Thurm, Simon Gaudin, Carolina Rios-Martinez, Benjamin R Doughty, Michaela M Hinks, Joydeb Sinha, Derek Le, Antonina Hafner, William J Greenleaf, Alistair N Boettiger, Lacramioara Bintu.

Repressive chromatin modifications compact chromatin and mediate heritable gene silencing, but how structural changes quantitatively relate to epigenetic memory remains unclear. Using targeted recruitment of the KRAB repressor to induce H3K9me3 at a reporter gene, combined with single-molecule 3D chromatin imaging, we show that irreversible silencing is associated with large-scale chromatin compaction across tens of kilobases. In contrast, histone deacetylation produces reversible silencing without such compaction. Despite substantial single-cell heterogeneity, average compaction at the end of silencing quantitatively predicts epigenetic memory weeks after KRAB removal. Here, memory arises not through stable H3K9me3 domains but rather through a dynamic handoff in which H3K9me3 is gradually lost and replaced by DNA methylation. Stochastic simulations recapitulating these dynamics suggest that compaction enhances read-write feedback to promote this transition. Similar compaction is observed at endogenous loci during differentiation and fate commitment, suggesting that spatial organization may be predictive of epigenetic memory in other systems.

DOI: https://doi.org/10.1126/sciadv.aeb0060

Science. 2026 Jul 23. 393(6809): eadx0673

Human body single-cell atlas of three-dimensional genome organization and DNA methylation.

Higher-order chromatin structure and DNA methylation are critical for gene regulation, but how these vary across the human body remains unclear. We performed multiomic profiling of three-dimensional (3D) genome structure and DNA methylation for 86,689 single nuclei across 16 tissues, identifying 35 major and 206 cell subtypes. We revealed extensive changes in CG and non-CG methylation across cell types and characterized 3D chromatin structure at an unprecedented cellular resolution. Extensive discrepancies exist between cell types delineated by DNA methylation and genome structure, which indicates that the role of distinct epigenomic features in maintaining cell identity may vary by lineage. This study expands our understanding of the diversity of DNA methylation and chromatin structure and offers a reference for exploring gene regulation in human health and disease.

DOI: https://doi.org/10.1126/science.adx0673