Jie Hong

Zinc and ring finger protein 3 (ZNRF3) functions as a transmembrane E3 ubiquitin ligase. Although genome-wide association studies have implicated ZNRF3 in body fat distribution, the evidence from human genetics and animal models has been lacking. Here, through whole-exome sequencing of 1,944 obese individuals and 2,161 healthy lean control individuals, we identified a rare loss-of-function mutation in human ZNRF3 (p.V228L) observed exclusively in 8 obese individuals. These carriers exhibit increased hip circumference and subcutaneous fat area and lower fasting glucose levels compared with noncarriers. In mice, adipocyte-specific Znrf3 deletion leads to progressive adiposity, with expansion of subcutaneous white adipose tissue (sWAT) and improved glucose tolerance after a long-term high-fat diet. Furthermore, Znrf3 deficiency impairs the browning capacity of sWAT and cold-induced thermogenesis. A knock-in mouse model harboring the homologous human p.V228L mutation recapitulates key features of carriers and knockout mice, including reduced sWAT thermogenic function, altered fat distribution, and improved glucose tolerance. Mechanistically, Znrf3 loss attenuates the cAMP/cAMP-dependent protein kinase signaling pathway, suppressing UCP1 expression and mitochondrial respiration. Collectively, these findings provide genetic and biological evidence that ZNRF3 regulates thermogenic capacity and remodeling of sWAT, offering new insights into obesity heterogeneity. Article Highlights: A rare loss-of-function variant in ZNRF3 (p.V228L) is enriched in individuals with obesity and is associated with increased subcutaneous white adipose tissue (sWAT) accumulation and lower fasting glucose levels. Both adipocyte-specific Znrf3 knockout and global variant knock-in impair sWAT browning, increase sWAT expansion, and improve glucose tolerance in mice. These findings establish ZNRF3 as a genetic regulator of fat distribution and thermogenic capacity, informing precise phenotyping of obesity. GWAS has implicated ZNRF3 in human fat distribution, yet its role in adipose tissue biology remains unknown.

Aims: To evaluate the impact of applying the International Diabetes Federation (IDF) 1‐hour plasma glucose (1h‐PG) criteria on diagnosing dysglycaemia in young Chinese adults with obesity, and to validate the metabolic basis and diagnostic performance of these criteria in this high‐risk population. Methods: This Cross‐Sectional Study Included 2484 Obese Individuals (Aged 18–40 Years, BMI ≥ 28 kg/m ² ). Participants underwent a 75‐g oral glucose tolerance test (OGTT). Glycaemic status was classified using both traditional American Diabetes Association (ADA) criteria (fasting and 2‐hour PG) and the IDF criteria (1h‐PG cutoffs: 8.6 mmol/L for intermediate hyperglycaemia, 11.6 mmol/L for diabetes). Insulin sensitivity, secretion and β‐cell function indices were calculated. Reclassification patterns were assessed, and the diagnostic accuracy of the 1h‐PG cutoffs was evaluated using receiver operating characteristic (ROC) curve analysis against the ADA criteria. Results: Applying IDF criteria doubled the prevalence of diabetes (from 12.0% to 22.7%) and significantly increased total dysglycaemia. This newly identified dysglycaemic population exhibited an intermediate metabolic phenotype with worsening insulin resistance and impaired early‐phase β‐cell function. ROC analysis demonstrated excellent diagnostic accuracy for the IDF diabetes cutoff (11.6 mmol/L; AUC 0.927), which matched the population‐optimal cutoff. The cutoff for intermediate hyperglycaemia (8.6 mmol/L) showed high sensitivity (86.8%) for detecting ADA‐defined prediabetes. Conclusions: The IDF 1h‐PG criteria uncover a substantial, previously unrecognised burden of dysglycaemia in young Chinese adults with obesity, supported by clear metabolic defects and strong diagnostic performance. These findings support the use of 1h‐PG as a practical tool for earlier risk stratification in this vulnerable population.

Obesity exhibits a high heritability with heterogeneity; however, the genetic variants identified as obesity-causing factors are still underexplored. By performing deep sequencing on 2295 cases of young-onset obesity from East Asian populations and 2292 lean controls, we identified five genes ( TUB , NR4A3 , HIST1H4D , DXO , and TELO2 ) with an excess burden of rare predicted loss-of-function (LoF) variants in cases. Among the variants, TUB p.R364G was identified as a potential deleterious variant that disrupted TUB protein’s subcellular localization. Knock-in mice carrying the homologous p.R363G variant exhibited hyperphagia and obesity in an allele dose–dependent manner when fed a high-fat diet. The TUB p.R363G variant also blunted responses to leptin-induced suppression of food intake, leading to leptin resistance in mice. Furthermore, we demonstrated that TUB acted as a positive regulator of the leptin pathway through its interaction with STAT3, and this interaction was impaired by the p.R364G variant. TUB silencing mitigated the inhibitory effects of leptin on the activities of agouti-related protein (AgRP)–expressing neurons. Consistently, conditional ablation of TUB in AgRP ⁺ neurons in mice led to hyperphagic obesity and attenuated leptin-induced appetite suppression in mice. Thus, our study demonstrates that rare LoF variants in TUB predispose to young-onset obesity in humans, likely through impairing leptin sensitivity in AgRP ⁺ neurons.

Lifestyle-induced weight loss improves metabolic health, but weight regain is common. Its hepatic consequences, particularly in relation to metabolic dysfunction–associated steatotic liver disease (MASLD), remain insufficiently characterized. This retrospective observational study included 213 patients categorized as weight regain (≥5% lifestyle-induced weight loss followed by return to or exceeding baseline weight) or weight sustain (weight change within ±5% of baseline) over 3 years. Propensity score matching (PSM) balanced age, sex, weight, and body mass index. Clinical, biochemical, and noninvasive liver indices were compared. In a bariatric surgery subset, liver histology, transcriptomics, quantitative PCR, and immunohistochemistry were performed. No significant differences were found in metabolic parameters between groups. After PSM, the weight regain group showed higher alanine aminotransferase (ALT) (median 59.00 vs 41.00 IU/L, P=0.007) and aspartate aminotransferase (AST) (33.50 vs 26.00 IU/L, P=0.041). In males, ALT (88.00 vs 47.00 IU/L, P<0.001) and AST (46.00 vs 30.00 IU/L, P=0.004) remained higher. Noninvasive indices of hepatic steatosis (Dallas Steatosis Index, DSI) and fibrosis (NFS, FIB-4) did not differ. In male patients with liver biopsy samples available, liver histology showed comparable NAFLD Activity Scores (NAS) and fibrosis stages, whereas transcriptomic analysis revealed immune-related pathway enrichment. Increased hepatic CD11B and CD68 expression was confirmed by quantitative PCR and immunohistochemistry. Weight regain after lifestyle-induced weight loss is associated with early liver-related biochemical abnormalities and hepatic innate immune activation in the absence of advanced fibrosis, underscoring the need for early liver risk assessment in individuals with weight cycling.

The gut microbiome is altered after bariatric surgery and is associated with weight loss. However, the commensal bacteria involved and the underlying mechanism remain to be determined. We performed shotgun metagenomic sequencing in obese subjects before and longitudinally after sleeve gastrectomy (SG), and found a significant enrichment in microbial species in Clostridia and bile acid metabolizing genes after SG treatment. Bile acid profiling further revealed decreased primary bile acids (PBAs) and increased conjugated secondary bile acids (C-SBAs) after SG. Specifically, glycodeoxycholic acid (GDCA) and taurodeoxycholic acid (TDCA) were increased at different follow-ups after SG, and were associated with the increased abundance of Clostridia and body weight reduction. Fecal microbiome transplantation with post-SG feces increased SBA levels, and alleviated body weight gain in the recipient mice. Furthermore, both Clostridia-enriched spore-forming bacteria and GDCA supplementation increased the expression of genes responsible for lipolysis and fatty acid oxidation in adipose tissue and reduced adiposity via Takeda G-protein-coupled receptor 5 (TGR5) signaling. Our findings reveal post-SG gut microbiome and C-SBAs as contributory to SG-induced weight loss, in part via TGR5 signaling, and suggest SBA-producing gut microbes as a potential therapeutic target for obesity intervention.