Biology subjects

Desrouleaux, R.

Publications and source records attributed to Desrouleaux, R..

3 recordsLinked to original sources

bioRxiv2024

Spatiotemporal control of subcellular O-GlcNAc signaling using Opto-OGT

The posttranslational modification of intracellular proteins through O-linked {beta}-N-acetylglucosamine (O-GlcNAc) is a conserved regulatory mechanism in multicellular organisms. Catalyzed by O-GlcNAc transferase (OGT), this dynamic modification plays an essential role in signal transduction, gene expression, organelle function, and systemic physiology. Here we present Opto-OGT, an optogenetic probe that allows for precise spatiotemporal control of OGT activity through light stimulation. By fusing a photosensitive cryptochrome protein to OGT, Opto-OGT can be robustly and reversibly activated with high temporal resolution by blue light and exhibits minimal background activity without illumination. Transient activation of Opto-OGT results in mTORC activation and AMPK suppression which recapitulate nutrient-sensing signaling. Furthermore, Opto-OGT can be customized to be localized at specific subcellular sites. By targeting OGT to the plasma membrane, we demonstrate downregulation of site-specific AKT phosphorylation and signaling outputs in response to insulin stimulation. Thus, Opto-OGT is a powerful tool to define the role of O-GlcNAcylation in cell signaling and physiology.

cell biology↗

bioRxiv2022

Gene Expression and Tracer-Based Metabolic Flux Analysis Reveals Tissue-Specific Metabolic Scaling in vitro, ex vivo, and in vivo

Metabolic scaling, the inverse correlation of metabolic rates to body mass, has been appreciated for more than 80 years. Studies of metabolic scaling have almost exclusively been restricted to mathematical modeling of oxygen consumption. The possibility that other metabolic processes scale with body size has not been studied. To address this gap in knowledge, we employed a systems approach spanning from transcriptomics to in vitro and in vivo tracer-based flux. Gene expression in livers of five species spanning a 30,000-fold range in mass revealed differential expression of genes related to cytosolic and mitochondrial metabolic processes, in addition to detoxication of oxidative damage. This suggests that transcriptional scaling of damage control mechanisms accommodates increased oxidative metabolism in smaller species. To determine whether flux through key implicated metabolic pathways scaled, we applied stable isotope tracer methodology to study multiple cellular compartments, tissues, and species. Comparing mice and rats, we demonstrate that while scaling of metabolic fluxes is not observed in the cell-autonomous setting, it is present in liver slices and in vivo. Together, these data reveal that metabolic scaling extends beyond oxygen consumption to numerous other metabolic pathways, and is likely regulated at the level of gene expression and substrate supply.

physiology↗

bioRxiv2020

Hepatic FGF21 mediates tissue tolerance during bacterial inflammation by preserving cardiac function

Sickness behaviors, including anorexia, are evolutionarily conserved responses to acute infections. Inflammation-induced anorexia causes dramatic metabolic changes, of which components critical to survival are unique depending on the type of inflammation. Glucose supplementation during the anorectic period induced by bacterial inflammation suppresses adaptive fasting metabolic pathways, including fibroblast growth factor-21 (FGF21), and decreases survival. Consistent with this observation, FGF21 deficient mice are more susceptible to mortality from endotoxemia and poly-bacterial peritonitis, but not viral infection. Here we report that increased circulating FGF21 during bacterial inflammation is hepatic-derived, promotes cardiac function, and is required for survival. FGF21 signaling downstream of its obligate co-receptor beta-Klotho (KLB) is required. However, mice with central nervous system or adipose-specific deletion of Klb do not demonstrate any difference in response to bacterial inflammation, suggesting that multiple tissues and/or a novel FGF21 target tissue are required for the full protective effect of FGF21. These data suggest that hepatic FGF21 is a novel cardioprotective factor in bacterial sepsis. eTOC SummaryIn response to bacterial inflammation, hepatic fibroblast growth factor 21 (FGF21), an endocrine hormone that mediates adaptive responses to metabolic stresses such as starvation, promotes survival by supporting heart function.

immunology↗