Biology subjects

Stefanoni, D.

Publications and source records attributed to Stefanoni, D..

4 recordsLinked to original sources

bioRxiv2024

Metabolic and Cellular Differences Between Sedentary and Active Individuals at Rest and During Exercise

BackgroundPhysical inactivity is a major contributor to cardiometabolic disease and mortality. Although mitochondrial dysfunction characterizes overt pathology, whether a distinct mitochondrial phenotype is present in apparently healthy sedentary adults remains unclear. MethodsNine sedentary (SED) and ten physically active (AC) healthy males (42 {+/-} 14 yr) were studied. Skeletal muscle bioenergetics were assessed using high-resolution respirometry, fluxomics, metabolomics and protein expression analyses. Whole-body physiology was evaluated using cardiopulmonary exercise testing (CPET) including fat oxidation and blood lactate measurements. ResultsAt rest, SED exhibited marked reductions in mitochondrial capacity, including Complex I (-36%), Complex II (-28%), electron transport system capacity (-34%), and ATP-synthase-coupled respiration (-30%, all p < 0.01). The most pronounced alteration was a 49% reduction in mitochondrial pyruvate carrier (MPC1) expression, which closely correlated with reduced pyruvate oxidation (-37%, p = 0.006) and lower TCA intermediates. SED also showed reduced MCT1 abundance, impaired fatty acid oxidation capacity (-32% to -35%), decreased CPT1 activity (-51%), altered cardiolipin composition and elevated ROS/O flux ratios. During exercise, SED demonstrated lower VO max (-38%), reduced fat oxidation (-35%) and higher blood lactate accumulation (>60%, p < 0.001). Mitochondrial function was strongly associated with exercise performance (r = 0.57-0.78, p < 0.01). ConclusionsHealthy sedentary adults are characterized by reduced mitochondrial function characterized by decreased substrate entry and oxidation, reduced oxidative capacity and diminished metabolic flexibility. CPET-derived fat oxidation and blood lactate responses closely reflect skeletal muscle mitochondrial function, providing non-invasive physiological markers of metabolic health. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=178 SRC="FIGDIR/small/608601v2_fig1.gif" ALT="Figure 1"> View larger version (51K): org.highwire.dtl.DTLVardef@1a3a629org.highwire.dtl.DTLVardef@f1ea48org.highwire.dtl.DTLVardef@4c4a96org.highwire.dtl.DTLVardef@b4f879_HPS_FORMAT_FIGEXP M_FIG O_FLOATNOFigure 1.C_FLOATNO Schematic of skeletal muscle mitochondrion: SED side shows reduced MPC, CPT1, L4CL, and TCA flux with elevated ROS; AC side shows robust OXPHOS, fat oxidation, and lactate clearance. Arrows link to CPET as a non-invasive diagnostic tool for mitochondrial health. C_FIG

biochemistry↗

bioRxiv2023

Inhibition of Asparagine Synthetase Effectively Retards Polycystic Kidney Disease Progression

Polycystic Kidney Disease (PKD) is a genetic disorder characterized by bilateral cyst formation. We showed that PKD cells and kidneys display metabolic alterations, including the Warburg effect and glutaminolysis, sustained in vitro by the enzyme asparagine synthetase (ASNS). Here, we used antisense oligonucleotides (ASO) against Asns in orthologous and slowly progressive PKD murine models and show that treatment leads to a drastic reduction of total kidney volume (measured by MRI) and a prominent rescue of renal function in the mouse. Mechanistically, the upregulation of an ATF4-ASNS axis in PKD is driven by the amino acid response (AAR) branch of the integrated stress response (ISR). Metabolic profiling of PKD or control kidneys treated with Asns-ASO or Scr-ASO revealed major changes in the mutants, several of which are rescued by Asns silencing in vivo. Indeed, ASNS drives glutamine-dependent de novo pyrimidine synthesis and proliferation in cystic epithelia. Notably, while several metabolic pathways were completely corrected by Asns-ASO, glycolysis was only partially restored. Accordingly, combining the glycolytic inhibitor 2DG with Asns-ASO further improved efficacy. Our studies identify a new therapeutic target and novel metabolic vulnerabilities in PKD.

biochemistry↗

bioRxiv2022

Metabolic Signatures of Performance in Elite World Tour Professional Cyclists

IntroductionMetabolomics studies of recreational and elite athletes have been so far limited to venipuncture-dependent blood sample collection in the setting of controlled training and medical facilities. However, limited to no information is currently available if findings in laboratory settings are translatable to real world scenario in elite competitions. MethodsTo characterize molecular profiles of exertion in elite athletes during cycling, we performed metabolomics analyses on blood isolated from twenty-eight international-level elite World Tour professional male athletes from a Union Cycliste Internationale (UCI) World Team taken before and after a graded exercise test (GXT) to volitional exhaustion and before and after a long aerobic training session. Moreover, established signatures were then used to characterize the metabolic physiology of five of these cyclists that were selected to represent the same UCI World Team during a 7-stage elite World Tour race. ResultsUsing dried blood spot collection to circumvent logistical hurdles associated with field sampling, these studies defined metabolite signatures and fold change ranges of anaerobic or aerobic exertion in elite cyclists, respectively. Blood signatures derived in controlled settings enabled comparison with blood sampled during competition, thus providing insight into fatigue status of the cyclists during the course of the race. Collectively, these studies provide a unique view of alterations in the blood metabolome of elite athletes during competition and at the peak of their performance capabilities. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=146 SRC="FIGDIR/small/507793v4_ufig1.gif" ALT="Figure 1"> View larger version (54K): org.highwire.dtl.DTLVardef@1a6bddeorg.highwire.dtl.DTLVardef@1fb6df5org.highwire.dtl.DTLVardef@1f0034eorg.highwire.dtl.DTLVardef@69053c_HPS_FORMAT_FIGEXP M_FIG C_FIG SummaryNemkov et al. leveraged field sampling and blood metabolomics and lipidomics approaches to follow a professional Team of elite cyclists upon graded exercise test to volitional exhaustion, field aerobic training (180 km) and a during multi-stage World Tour race. They identify markers of cycling performance beyond lactate thresholds (ranging from 3.75 to 6.5 watts per kilogram in this group), including carboxylic acids, fatty acids and acylcarnitines. Key pointsO_LIWe profiled metabolism of 28 international-level elite World Tour professional male athletes from a Union Cycliste Internationale UCI World Team during training and World Tour multi-stage race; C_LIO_LIDried blood spot sampling affords metabolomics analyses to monitor exercise performance; C_LIO_LIDetermination of lactate thresholds during graded exercise test (GXT) to volitional exhaustion shows a range of from 3.75 to 6.5 watts per kilogram in this group; C_LIO_LIBlood profiles of lactate, carboxylic acids, fatty acids and acylcarnitines differed between different exercise modes (GXT and 180 km aerobic training session); C_LIO_LIMetabolic profiles were affected by stage-specific challenges (sprint vs climbing) during a World Tour multi-stage race. C_LI

biochemistry↗

bioRxiv2019

Gene-diet interactions: dietary rescue of metabolic defects in spen-depleted Drosophila

Obesity and its co-morbidities are a growing health epidemic. Interactions between genetic background and the environment and behavior (i.e. diet) greatly influence organismal energy balance. Previously, we described obesogenic mutations in the gene Split ends (Spen) in Drosophila melanogaster, and roles for Spen in fat storage and metabolic state. In Spen-deficient storage cells lipid catabolism is impaired, accompanied by a compensatory increase in glycolytic flux and protein catabolism. Here we investigate gene-diet interactions to determine if diets supplemented with specific macronutrients can rescue metabolic dysfunction in Spen-depleted animals. We show that a high-yeast diet partially rescues adiposity and developmental defects. High sugar partially improves developmental timing as well as adult longevity. Gene-diet interactions were heavily influenced by developmental-stage-specific organismal needs: extra yeast provides benefits early in development (larval stages) but becomes detrimental in adulthood. High sugar confers benefits at both larval and adult stages, with the caveat of increased adiposity. A high-fat diet is detrimental according to all tested criteria, regardless of genotype. Whereas Spen depletion influenced phenotypic responses to supplemented diets, diet was the dominant factor in directing the whole-organism steady-state metabolome. Obesity is a complex disease of genetic, environmental, and behavioral inputs. Our results show that diet customization can ameloriate metabolic dysfunction underpinned by a genetic factor.

genetics↗