Biology subjects

Laguerre, A.

Publications and source records attributed to Laguerre, A..

7 recordsLinked to original sources

bioRxiv2026

IL-10/ACOD1 axis regulates catabolism of phagocytosed lipids in trained macrophages

Macrophages clear excess host and microbial debris to restore homeostasis in inflamed tissues, yet the regulation and molecular fate of phagocytosed lipids during innate immune training remains largely unexplored. Leveraging stable isotope tracing of 13C-labeled bacteria, we establish an experimental framework to track microbe-to-host lipid transfer and define the fates of microbial lipids in macrophages in vitro and in vivo. While naive macrophages scavenge phagocytosed bacterial fatty acids into the host lipidome, TLR4-trained macrophages direct flux to mitochondria for {beta}-oxidation or lipid droplets in the context of mitochondrial dysfunction. While TLR4 signaling increases ACOD1 expression to produce itaconate that throttles TCA flux, trained macrophages produce IL-10 that reduces ACOD1 to sustain bacterial lipid disposal and promote resolution. These findings reveal an IL-10/ACOD1 regulatory axis in trained macrophages that reprograms lipid metabolism to optimally reestablish tissue homeostasis post-inflammation.

immunology↗

bioRxiv2026

Identifying Novel Estrogenic Mitochondrial Targets in Hypothalamic Proopiomelanocortin Neurons by Chemoproteomics

Loss of estrogens at menopause is linked to impaired brain metabolism and increased risk of Alzheimers disease (AD). However, estrogen replacement therapies are limited due to the deleterious effects of estrogen on peripheral organs and increased risk of vascular dementia. We have developed a non-steroidal estrogenic compound, STX, which does not bind to the classical estrogen receptors and {beta}, but mimics estrogenic signaling in the central nervous system (CNS) without the peripheral reproductive actions. STX is protective against neurodegeneration in stroke and AD models, but its molecular targets are unknown. Here, we identified and validated STX neural targets using chemoproteomic, molecular biological, electrophysiological and metabolic assays of hypothalamic proopiomelanocortin (POMC) neurons. Chemoproteomic profiling identified voltage dependent anion channels (VDAC1-3) as major intracellular binding partners in mHypo43 (POMC) cells. Based on quantitative single-cell PCR, Vdac2 was identified as the dominant isoform in female hypothalamic POMC neurons. Seahorse metabolic flux analyses showed that STX potently increased glycolysis, oxidative respiration and mitochondrial ATP production in mHypo43 cells. Nanomolar concentrations of STX enhanced VDAC2 voltage-dependent gating in reconstituted lipid membranes and shifted the low-conductance states toward anion selectivity, consistent with increased ATP flux. Together, these findings reveal a mechanism for the neuroprotective effects of STX through enhancing mitochondrial bioenergetics and modulating VDAC channel properties, potentially increasing cellular energy stores. Therefore, this work identifies previously unrecognized estrogenic mitochondrial targets and provides a mechanistic basis for the neuroprotective actions of STX relevant to menopause-associated brain vulnerability.

neuroscience↗

bioRxiv2025

Targeting serine dehydratase supports amino acid homeostasis and skin repair

Serine and glycine are altered in patients with metabolic disorders, and this dysregulation can lead to diverse pathologies1-6. Modulation of serine levels via diet can influence relevant phenotypes in mouse models of metabolic syndrome7,8. Here we identify serine dehydratase (Sds), a gluconeogenic hepatic enzyme involved in serine and threonine catabolism, as a key regulator of systemic serine and sphingolipid metabolism. We show that SDS is expressed and active in human liver tissue. Furthermore, Sds abundance strongly correlates with hepatic serine. This enzyme is highly active in BKS-db/db mice, which show amino acid alterations reminiscent of type 2 diabetes. Hepatic Sds overexpression increases serine and threonine degradation and promotes the accumulation of toxic 1-deoxysphingolipids (doxSLs). Conversely, Sds deletion dramatically increases systemic serine, glycine, and threonine while altering canonical and non-canonical sphingolipids. Finally, Sds deletion in BKS-db/db mice reduces skin doxSLs and accelerates wound healing. Our results demonstrate that Sds constrains serine levels in circulation and suggest therapeutic approaches for targeting this enzyme to improve chronic disorders.

physiology↗

bioRxiv2025

1-Deoxysphingolipids dysregulate membrane properties and cargo trafficking in the early secretory pathway

1-Deoxysphingolipids are non-canonical sphingolipids linked to several diseases, but their cellular effects are poorly understood. Here, we utilize lipid chemical biology approaches to investigate the role of 1-deoxysphingolipid metabolism on the properties and functions of secretory membranes. We first applied organelle-specific bioorthogonal labeling to visualize the subcellular distribution of metabolically tagged 1-deoxysphingolipids in RPE-1 cells, observing that they are retained in the endoplasmic reticulum (ER). We found that 1-deoxysphingolipids can be transported by the non-vesicular transporter CERT in vitro but are retained at ER exit sites (ERES) in cells, suggesting that they do not efficiently sort into vesicular carriers. Cells expressing disease-associated variants of serine palmitoyl-CoA transferase (SPT) accumulated long-chain 1-deoxysphingolipids, which reduced ER membrane fluidity and enlarged ERES. We observed that the rates of membrane protein release from the ER were altered in response to mutant SPT expression, in a manner that was dependent on the cargo affinity for ordered or disordered membranes. We propose that dysregulation of sphingolipid metabolism alters secretory membrane properties, which can then modulate protein trafficking.

cell biology↗

bioRxiv2024

Trace Amines are Essential Metabolites for the Autocrine Regulation of β-Cell Signaling and Insulin Secretion

Secretion of insulin in response to extracellular stimuli, such as elevated glucose levels and small molecules that act on G-protein coupled receptors (GPCRs), is the hallmark of {beta}-cell physiology. Trace amines (TAs) are small aromatic metabolites that were identified as low-abundant ligands of the trace amine-associated receptor 1 (TAAR1) in the central nervous system (CNS), a GPCR that is also expressed by pancreatic {beta}-cells. In the present work, we identify TAs as essential autocrine signaling factors for {beta}-cell activity and insulin secretion. We find that {beta}-cells are producing TAs in significant amounts and that the modulation of endogenous TA levels by the selective inhibition of TA biosynthetic pathways directly translated into changes of oscillations of the intracellular Ca2+ concentration ([Ca2+]i oscillations) and insulin secretion. Selective TAAR1 agonists or inhibitors of monoamine oxidases increased [Ca2+]i oscillations and insulin secretion. Opposite effects were mediated by selective TAAR1 antagonists, by recombinant monoamine oxidase action and by the inhibition of amino acid decarboxylase. As the modulation of TA biochemical pathways immediately translated into changes of [Ca2+]i oscillations, we inferred high metabolic turnover rates of TAs and autocrine feedback. We found that psychotropic drugs modulate [Ca2+]i oscillations and insulin secretion, either directly acting on TAAR1 or by altering endogenous TA levels. Our combined data support the hypothesis of TAs as essential autocrine signaling factors for {beta}-cell activity and insulin secretion as well as TAAR1 as an important mediator of amine-modulated insulin secretion.

biochemistry↗

bioRxiv2024

Cannabinoid Receptor Signaling is Dependent on Sub-Cellular Location

G protein-coupled receptors (GPCRs) are membrane bound signaling molecules that regulate many aspects of human physiology. Recent advances have demonstrated that GPCR signaling can occur both at the cell surface and internal cellular membranes. Our findings suggest that cannabinoid receptor 1 (CB1) signaling is highly dependent on its subcellular location. We find that intracellular CB1 receptors predominantly couple to Gi while plasma membrane receptors couple to Gs. Here we show subcellular location of CB1, and its signaling, is contingent on the choice of promoters and receptor tags. Heterologous expression with a strong promoter or N-terminal tag resulted in CB1 predominantly localizing to the plasma membrane and signaling through Gs. Conversely, CB1 driven by low expressing promoters and lacking N-terminal genetic tags largely localized to internal membranes and signals via Gi. Lastly, we demonstrate that genetically encodable non-canonical amino acids (ncAA) offer a solution to the problem of non-native N-terminal tags disrupting CB1 signaling. We identified sites in CB1R and CB2R which can be tagged with fluorophores without disrupting CB signaling or trafficking using (trans-cyclooctene attached to lysine (TCO*A)) and copper-free click chemistry to attach fluorophores in live cells. Together, our data demonstrate the origin of location bias in cannabinoid signaling which can be experimentally controlled and tracked in living cells through promoters and novel CBR tagging strategies.

molecular biology↗

bioRxiv2021

Incorporation of unnatural amino acid for the tagging of cannabinoid receptors 1 and 2 reveals receptor roles in regulating cAMP levels

The role of CB1/CB2 co-expression in cell signaling remains elusive. We established a simplified mammalian cell model system in which expression of CB1 or CB2 can be easily monitored under a confocal microscope. For this, we applied amber codon suppression in live cells to incorporate a single trans-cyclooctene (TCO) bearing amino acid in one of the extracellular loops of CB1 or CB2, followed by fluorescent labeling via click chemistry. We employed genetically encoded biosensors to measure the roles of CB1 and/or CB2 in regulating intracellular calcium ([Ca2+]i) and cAMP ([cAMP]i) levels. We show that the agonist-mediated activation of tagged-CB1 or -CB2 can transiently elevate [Ca2+]i levels. However, when the two receptors were co-expressed in the same cell, CB2 no longer signaled through calcium although CB1-mediated transient elevation of [Ca2+]i levels was unaffected. Because of the existence of crosstalk between calcium and cAMP signaling, we measured the effects of CB1 and/or CB2 in regulating adenylate cyclase activity. We found that the expression of CB1 increased forskolin-induced [cAMP]i levels compared to non-transfected cells. Conversely, CB2 expression decreased stimulated [cAMP]i levels under the same conditions. Finally, co-expressed CB1 and CB2 receptors showed additive yet opposing effects on stimulated [cAMP]i levels. These observations suggest that co-expressed CB1/CB2 act locally as a pair in regulating cell excitability by modulating stimulated [cAMP]i levels.

cell biology↗