Molecular Metabolism最新文献

Objectives: Brown adipose tissue (BAT) dissipates energy via non-shivering thermogenesis, but durable thermogenic benefit requires sustained cold remodeling that stabilizes a cold-adapted tissue state. While most studies have focused on adipocyte-intrinsic pathways that drive acute activation, how stromal niche cells-particularly the vasculature-sense and coordinate long-term adaptation remains poorly defined. Because GPCRs are key sensors of extracellular and neurohumoral cues, we mapped GPCR expression across mouse and human BAT at single-nucleus resolution and identified adhesion GPCRs as a prominent family enriched in vascular cells, with endothelial ADGRF5(GPR116) emerging as a leading candidate regulator.

Methods: Single-nucleus RNA sequencing of mouse and human BAT was used to map GPCR expression across cell types. Global, inducible endothelial-specific, and adipocyte-specific ADGRF5(GPR116) knockout mouse models were each challenged with acute and prolonged cold exposure. Endothelial and adipocyte states were analyzed using single-nucleus RNA sequencing transcriptional profiling, functional vascular assays, and cell-cell communication modeling.

Results: Endothelial deletion of ADGRF5(GPR116) impaired the ability of mice to sustain thermogenesis during prolonged cold exposure, whereas adipocyte-specific deletion did not affect thermogenic capacity in vivo. Loss of endothelial ADGRF5(GPR116) did not alter endothelial cell abundance, but induced endothelial transcriptional reprogramming characterized by disrupted quiescent remodeling programs, shifts in endothelial state with EndMT-like features, and context-dependent alterations in barrier-associated pathways, occurring in the absence of immune cell infiltration or overt fibrosis. Adipocyte reclustering revealed a failure to acquire a fully cold-adapted thermogenic state, with thermogenically inefficient programs and adrenergic hyporesponsiveness, despite preserved sympathetic input. CellChat and NicheNet analyses predicted altered endothelial-derived paracrine signaling capable of reshaping adipocyte identity.

Conclusions: Endothelial ADGRF5(GPR116) is a critical regulator of vascular adaptation during sustained cold exposure and supports full acquisition of the thermogenic adipocyte state through endothelial identity and paracrine signaling.

Glucagon-like peptide-1 receptor (GLP-1R) activation in the brain strongly reduces appetite, but most brain GLP-1Rs are not accessible for systemically administered GLP-1R agonists. Acute activation of nucleus tractus solitarius (NTS) GLP-1 neurons, known as preproglucagon (PPG) neurons, strongly suppresses food intake separate from GLP-1R agonists. However, it is unknown if chronic stimulation of PPG neurons is a viable strategy for appetite suppression, or if obesity disrupts their function. Here we demonstrate that PPG neurons in the NTS and intermediate reticular nucleus (IRT) determine meal size, and that their total number is inversely correlated with bodyweight gain. We report that PPG^NTS and PPG^IRT neurons receive distinct monosynaptic inputs, but have convergent efferent projection targets throughout the brain, and that combined ablation of both populations delays the onset of physiological satiation to a degree sufficient to promote weight gain under ad libitum chow fed conditions. Crucially, chronic daily chemogenetic activation of PPG^NTS+IRT neurons drives robust and sustained hypophagia and weight loss in obese mice without notable adverse effects, demonstrating their value as targets for obesity pharmacotherapy.

Rod and cone photoreceptors are among the most energy-demanding cells in the body, exhibiting a high rate of ATP consumption. Their primary energy source is glucose, which is metabolized through both glycolysis and mitochondrial pyruvate oxidative phosphorylation. The pyruvate dehydrogenase E1 subunit α1 is a critical component of the pyruvate dehydrogenase, which catalyzes the conversion of pyruvate to acetyl-CoA, thereby regulating mitochondrial pyruvate metabolism. To determine the significance of mitochondrial pyruvate metabolism in these cells, we investigated the impact of photoreceptor-specific Pdha1 deletion in the mouse retina. Rod- or cone-specific Pdha1 knockout mice at 2-5 months were used. These mice were evaluated across multiple modalities, including retinal structure and integrity (morphometry), retinal function (electroretinogram), photoreceptor ultrastructure (transmission electron microscopy), retinal metabolic profiles (mass spectrometry), gene expression (RT-PCR), and retinal stress response (glial activation analysis). Mice with rod- or cone-specific Pdha1 deletion exhibited retinal degeneration phenotype, manifested by impaired retinal morphology and light responses and significant retinal glial activation. Mechanistically, these retinas displayed profound metabolism reprogramming, evidenced by changes in key glycolysis and decreased tricarboxylic acid (TCA) cycle intermediates, carbohydrates, amino acids, nucleotides and their derivatives. This metabolic remodeling was further supported by enhanced glycolysis and decreased TCA cycle gene expression and was accompanied by impaired mitochondrial morphology. Our findings demonstrate that PDHA1 is essential for photoreceptor energy metabolism and for maintaining both their structural and functional integrity, thus highlighting the critical importance of proper mitochondrial glucose metabolism for photoreceptor health.

Hypoparathyroidism is a rare endocrine disorder characterized by hypocalcemia, hyperphosphatemia, and low or undetectable levels of parathyroid hormone (PTH). Advanced treatments that precisely maintain blood calcium levels within the normal range to improve disease symptoms and outcomes are needed. Canvuparatide (formerly known as MBX 2109) is a once-weekly investigational PTH analog that undergoes a controlled-release conversion to a biologically active peptide through an intramolecular cyclization reaction controlled by temperature and pH. Here we demonstrate the biologically active PTH analog, derived from the canvuparatide prodrug, stimulated dose-dependent accumulation of cyclic AMP to a similar degree and selectivity as a synthetic form of the human PTH(1-34) peptide in human cells overexpressing the PTH type 1 receptor. In healthy rats treated with canvuparatide at 4-40 nmol/kg/day for 28 days and healthy cynomolgus monkeys treated with single doses of canvuparatide 3.75-7.5 nmol/kg, prodrug and active peptide concentrations increased dose proportionally and correlated with increases in serum calcium concentrations. In parathyroidectomized rats, canvuparatide treatment at 10-40 nmol/kg normalized serum calcium levels and increased bone formation in a dose-proportional manner. In a phase 1, randomized, placebo-controlled study (NCT05158335), single subcutaneously administered doses of canvuparatide (50-600 μg) were well tolerated in healthy volunteers. Pharmacokinetic clinical profiles displayed geometric mean t_1/2 values of 81-101 (canvuparatide prodrug) and 133-186 h (canvuparatide active peptide) across dose groups, supporting once-weekly dosing. These collective findings support clinical advancement of once-weekly canvuparatide therapy for patients with hypoparathyroidism.