Biology subjects

Galmozzi, A.

Publications and source records attributed to Galmozzi, A..

8 recordsLinked to original sources

bioRxiv2026

Folic acid polyglutamylation triggers MAP2K5 signaling to induce adipocyte lipid catabolism

Adipocyte signaling adaptively responds to macronutrients, but how essential micronutrients impact lipid homeostasis remains poorly understood. Here, we demonstrate that folate polyglutamylation, the sequential conjugation of glutamate residues to folate, serves as a dynamic biochemical process regulating metabolic signaling. Using our folate metabolomics platform, we show that polyglutamylated folic acid accumulates in healthy adipose tissue, but is depleted in obesity across mice and humans, independent of circulating folate levels. Genetic ablation of the polyglutamylation enzyme folylpolyglutamate synthase (Fpgs) in adipocytes suppresses lipid catabolism to induce cell-autonomous lipid accumulation, operating independently of canonical adipogenesis or downstream one-carbon flux. Target-engagement proteomics identifies monoglutamylated folic acid as a Map2k5-interacting molecule that inhibits Map2k5 activity, whereas Fpgs-mediated folic acid polyglutamylation acts as a chemical switch that disrupts this interaction to promote lipolysis. In vivo, whole-body inhibition of Map2k5 or adipose-targeted genetic depletion of Fpgs increases body fat mass in the absence of dietary obesogenic triggers. Furthermore, single-cell and single-nuclear transcriptomic analyses establish the Fpgs-Map2k5 pathway as a core transcriptional signature of mouse and human adipose tissues. These findings uncover a non-canonical signaling role for folate that regulates adipocyte lipid homeostasis.

biochemistry↗

bioRxiv2026

Atlas of lysine acetylation in the mouse

Lysine acetylation has widespread ramifications from genetic regulatory effects to modulation of enzymatic function. With improved acetyl-lysine enrichment technologies and advances in mass spectrometer speed and sensitivity, we present a comprehensive atlas of the mouse acetylome comprising 17,952 unique lysine acetylation sites across 4,340 proteins and 15 tissues. This resource, which nearly doubles the known mouse acetyl-lysine catalog, shows at least 14% of the acetylome is shared across tissues. We focus our investigation on several acetylated proteins, including ribosomal acetylation and its potential to extend ribosomal half-life in the liver and pancreas. Additionally, we identify a novel acetylation event in the active site of carnitine O-acetyltransferase (Crat) that also mirrors tissue-specific Crat activity. By integrating these data with human pathogenic variants, we identify acetyl-lysine residues on cardiac troponin and homogentisate dioxygenase that likely mimic disease-causing mutations. This resource provides a foundational framework for investigating protein acetylation in metabolic health and disease.

biochemistry↗

bioRxiv2025

Tumor-Derived Polyamines Initiate Fat Wasting in Cancer Cachexia

Cancer-associated cachexia (CC) is a fatal metabolic condition characterized by progressive loss of fat and muscle mass, yet its early molecular drivers remain poorly defined. Here, we identify a polyamine-dependent tumor-adipose crosstalk that triggers adipocyte lipolysis and fat wasting during the pre-cachexia stage, preceding systemic inflammation and muscle atrophy. Cancer-derived polyamines are enriched in extracellular vesicles and promote lipid mobilization via eIF5A hypusination, independent of adrenergic signaling. In preclinical models, polyamine accumulation associates with early fat loss and elevated circulating fatty acids. Clinically, automated CT imaging of newly diagnosed pancreatic cancer patients reveals increased adipose density, reflecting lipolysis, that correlates with circulating polyamine levels and predicts poor survival. These findings support polyamine metabolism as a mechanistic driver and candidate biomarker of early cachexia, providing a framework for early detection and targeted intervention.

cancer biology↗

bioRxiv2025

White and Brown Adipose Tissue Share a Common Fibro-Adipogenic Progenitor Population

Adipose tissue heterogeneity has emerged as a central factor in regulating adipose tissue function in physiology and pathophysiology, yet tools to model and study this diversity in vitro remain limited. Here, we performed single-cell RNA sequencing on cultured primary white and brown preadipocytes to assess how in vitro conditions impact progenitor identity. We identified two major subpopulations in both depots: committed adipogenic precursors (CAPs) and fibro-adipogenic progenitor-like cells (FAPLs). Remarkably, FAPLs were also present in brown adipose tissue, expanding the known landscape of progenitor populations in this depot. Trajectory and regulon analyses revealed that both white and brown FAPLs exhibit similar pro-fibrotic, stress-responsive signatures and diverge early from proliferating progenitor states. Integration of datasets showed that FAPLs from both depots cluster together, emphasizing their conserved identity, while CAPs remain depot-specific. Comparison to previously published in vivo single-cell datasets revealed that these in vitro populations, including brown adipose FAPLs, correspond to adipose-resident progenitor subtypes, validating the physiological relevance of this model for studying adipose tissue heterogeneity and development.

physiology↗

bioRxiv2024

DUALISTIC SAHA DOSE-DEPENDENT EFFECTS ON GLIAL-INFLAMMATORY RESPONSE

Neuroinflammation comprises biochemical and cellular responses of the nervous system to injury, emerging as a central process in many neurological conditions. Although beneficial in nature, over-activation of the immune response may result in the production of neurotoxic factors that exacerbate the disease state. Due to the relevant role of histone acetylation in transcriptional regulation, inhibition of histone deacetylase (HDAC) activity plays a central role in the pathogenesis of inflammation. Here, we investigated the impact of HDACs inhibition in the regulation of the inflammatory response elicited by lipopolysaccharide (LPS) in glia cells using trichostatin A (TSA) and suberoylanilide hydroxamic acid (SAHA). We observed that acute and prolonged exposure to low doses of TSA boosts the inflammatory response in glia cells. Conversely, TSA pre-treatment in cells exposed to LPS decreases inflammation. Additionally, we observed that low and high doses of SAHA exert opposite effects on LPS-induced inflammatory response. Low dose (100 nM) potentiates inflammatory response by increasing the production of pro-inflammatory cytokines tumour necrosis factor (TNF)- and interleukin (IL) - 1{beta}; and reducing the anti-inflammatory mediator IL-10. Nevertheless, 5 {micro}M SAHA reverts the pro-towards anti-inflammatory profile. To better characterize SAHA dualistic effects in glia cells, we generated comparative genome-wide gene expression data. Simultaneous exposure to 5 {micro}M SAHA and LPS (10 ng/ml) alters the expression of 1628 genes, while the combination of 100 nM SAHA and LPS regulates the expression of 97 transcripts. Both doses of SAHA differentially regulate important pathways involved in cellular function maintenance, homeostasis, and survival. Likewise, inhibition of the Janus Kinase - signal transducers and activators of the transcription (JAK/STAT) signalling pathway seems to mediate the anti-inflammatory effects of 5 {micro}M SAHA. On the other hand, 100 nM SAHA increases pro-inflammatory cytokine levels possibly via modulation of the underlined feedback mechanisms triggered by IL-10 expression regulation. Together, these results contribute to outline a comprehensive picture of the involvement of HDACs inhibitors (HDACi) in the onset or prevention of neuroinflammation, showing that their effects depend on cell types, HDACi dosage and specificity, and protocol used.

molecular biology↗

bioRxiv2023

Heme biosynthesis regulates BCAA catabolism and thermogenesis in brown adipose tissue

With age, people tend to accumulate body fat and reduce energy expenditure1. Brown (BAT) and beige adipose tissue dissipate heat and increase energy expenditure via the activity of the uncoupling protein UCP1 and other thermogenic futile cycles2,3. The activity of brown and beige depots inversely correlates with BMI and age4-11, suggesting that promoting thermogenesis may be an effective approach for combating age-related metabolic disease12-15. Heme is an enzyme cofactor and signaling molecule that we recently showed to regulate BAT function16. Here, we show that heme biosynthesis is the primary contributor to intracellular heme levels in brown adipocytes. Inhibition of heme biosynthesis leads to mitochondrial dysfunction and reduction in UCP1. Although supplementing heme can restore mitochondrial function in heme-synthesis-deficient cells, the downregulation of UCP1 persists due to the accumulation of the heme precursors, particularly propionyl-CoA, which is a product of branched-chain amino acids (BCAA) catabolism. Cold exposure promotes BCAA uptake in BAT, and defects in BCAA catabolism in this tissue hinder thermogenesis17. However, BCAAs contribution to the TCA cycle in BAT and WAT never exceeds 2% of total TCA flux18. Our work offers a way to integrate current literature by describing heme biosynthesis as an important metabolic sink for BCAAs.

cell biology↗

bioRxiv2023

One-Hour Phosphoproteome Analysis with the Orbitrap Astral Mass Spectrometer

Owing to its roles in cellular signal transduction, protein phosphorylation plays critical roles in myriad cell processes. That said, detecting and quantifying protein phosphorylation has remained a challenge. We describe the use of a novel mass spectrometer (Orbitrap Astral) coupled with data-independent acquisition (DIA) to achieve rapid and deep analysis of human and mouse phosphoproteomes. With this method we map approximately 30,000 unique human phosphorylation sites within a half-hour of data collection. The technology was benchmarked to other state-of-the-art MS platforms using both synthetic peptide standards and with EGF-stimulated HeLa cells. We applied this approach to generate a phosphoproteome multi-tissue atlas of the mouse. Altogether, we detected 81,120 unique phosphorylation sites within 12 hours of measurement. With this unique dataset, we examine the sequence, structural, and kinase specificity context of protein phosphorylation. Finally, we highlight the discovery potential of this resource with multiple examples of novel phosphorylation events relevant to mitochondrial and brain biology.

systems biology↗

bioRxiv2020

Pharmacologic IRE1/XBP1s Activation Promotes Systemic Adaptive Remodeling in Obesity

In obesity, overexpression of the IRE1-regulated transcription factor XBP1s protects against metabolic dysfunction by stimulating adaptive remodeling of multiple tissues, most notably the liver.1-5 This observation suggests that pharmacologically increasing IRE1/XBP1s signaling might be an attractive approach to mitigate pathologies in obesity and its associated complications.6-8 Here, we tested this notion by treating diet-induced obese (DIO) mice with the pharmacologic IRE1/XBP1s activator IXA4.9 We show that IXA4 treatment selectively activated protective IRE1/XBP1s signaling in livers of DIO mice without inducing obesity-linked pathologies associated with IRE1 hyperactivity, such as liver inflammation and fibrosis.10,11 Chronic IXA4 treatment improved systemic glucose metabolism and feeding-induced insulin action in the liver of DIO mice. These improvements were linked to IRE1/XBP1s-induced remodeling of the liver transcriptome, which dampened glucose production and reduced hepatic steatosis. Further, we show that IXA4 treatment enhanced pancreatic {beta} cell function and insulin homeostasis, indicating that systemic activation of IRE1/XBP1s signaling engendered multi-tissue benefits that integrated to mitigate systemic metabolic dysfunction in DIO mice. Our findings show that selective pharmacological activation of protective IRE1/XBP1s signaling reprograms multiple metabolic tissues, such as liver and pancreas, and represents a potential strategy to correct metabolic alterations in obesity.

physiology↗