Biology subjects

San-Millan, I.

Publications and source records attributed to San-Millan, I..

3 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

Role of Lactate in the Regulation of Transcriptional Activity of Breast Cancer-Related Genes and Epithelial-to-Mesenchymal Transition Proteins: A Comparison of MCF7 and MDA-MB-231 Cancer Cell Lines

The Warburg Effect is characterized by accelerated glycolytic metabolism and lactate production and under fully aerobic conditions is a hallmark of cancer cells. Recently, we have demonstrated the role of endogenous, glucose-derived lactate as an oncometabolite which regulates gene expression in the estrogen receptor positive (ER+) MCF7 cell line cultivated in glucose media. Presently, with the addition of a triple negative breast cancer (TNBC) cell line, MDA-MB-231, we further confirm the effect of lactate on gene expression patterns and extend results to include lactate effects on protein expression. As well, we report effects of lactate on the expression of E-cadherin and vimentin, proteins associated with epithelial-to-mesenchymal transition (EMT). Endogenous lactate regulates the expression of multiple genes involved in carcinogenesis. In MCF7 cells, lactate increased the expression of EGFR, VEGF, HIF-1a, KRAS, MIF, mTOR, PIK3CA, TP53, and CDK4 as well as decreased the expression of ATM, BRCA1, BRCA2, E2F1, MET, MYC, and RAF mainly after 48h of exposure. On the other hand, in the MDA-MB-231 cell line, lactate increased the expressions of PIK3CA, VEGF, EGFR, mTOR, HIF-1, ATM, E2F1, TP53 and decreased the expressions of BRCA1, BRCA2, CDK4, CDK6, MET, MIF, MYC, and RAF after 48h of exposure. In response to endogenous lactate, changes in protein expression of representative genes corroborated changes in mRNA expressions. Finally, lactate exposure decreased E-cadherin protein expression in MCF7 cells and increased vimentin expression in MDA-MB-231 cells. Further-more, by genetically silencing LDHA in MCF7 cells, we show suppression of protein expression of EGFR and HIF-1, while full protein expression occurred under glucose and glucose + exogenous lactate exposure. Hence, endogenous, glucose-derived lactate, and not glucose, elicited changes in gene and protein expression levels. In this study, we demonstrate that endogenous lactate produced under aerobic conditions (Warburg Effect) elicits important changes in gene and protein expression in both ER+ and TNBC cell lines. The widespread regulation of multiple genes by lactate and involves those involved in carcinogenesis including DNA repair, cell growth, proliferation, angiogenesis, and metastasis. Furthermore, lactate affected the expression of two relevant EMT biomarkers, E-cadherin and vimentin, which could contribute to the complex process of EMT and a shift towards a more mesenchymal phenotype in the two cancer cell lines studied.

cancer biology↗

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↗