Browsing by Author "Raymond F"

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    Mitochondrial oxidative capacity and NAD+ biosynthesis are reduced in human sarcopenia across ethnicities
    (Springer Nature Limited, 2019-12-20) Migliavacca E; Tay SKH; Patel HP; Sonntag T; Civiletto G; McFarlane C; Forrester T; Barton SJ; Leow MK; Antoun E; Charpagne A; Seng Chong Y; Descombes P; Feng L; Francis-Emmanuel P; Garratt ES; Giner MP; Green CO; Karaz S; Kothandaraman N; Marquis J; Metairon S; Moco S; Nelson G; Ngo S; Pleasants T; Raymond F; Sayer AA; Ming Sim C; Slater-Jefferies J; Syddall HE; Fang Tan P; Titcombe P; Vaz C; Westbury LD; Wong G; Yonghui W; Cooper C; Sheppard A; Godfrey KM; Lillycrop KA; Karnani N; Feige JN
    The causes of impaired skeletal muscle mass and strength during aging are well-studied in healthy populations. Less is known on pathological age-related muscle wasting and weakness termed sarcopenia, which directly impacts physical autonomy and survival. Here, we compare genome-wide transcriptional changes of sarcopenia versus age-matched controls in muscle biopsies from 119 older men from Singapore, Hertfordshire UK and Jamaica. Individuals with sarcopenia reproducibly demonstrate a prominent transcriptional signature of mitochondrial bioenergetic dysfunction in skeletal muscle, with low PGC-1α/ERRα signalling, and downregulation of oxidative phosphorylation and mitochondrial proteostasis genes. These changes translate functionally into fewer mitochondria, reduced mitochondrial respiratory complex expression and activity, and low NAD+ levels through perturbed NAD+ biosynthesis and salvage in sarcopenic muscle. We provide an integrated molecular profile of human sarcopenia across ethnicities, demonstrating a fundamental role of altered mitochondrial metabolism in the pathological loss of skeletal muscle mass and function in older people.
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    Transcriptome and translational signaling following endurance exercise in trained skeletal muscle: Impact of dietary protein
    (American Physiological Society, 2011) Rowlands DS; Thomson JS; Timmons BW; Raymond F; Fuerholz A; Mansourian R; Zwahlen M-C; Métairon S; Glover E; Stellingwerff T; Kussmann M; Tarnopolsky MA
    Postexercise protein feeding regulates the skeletal muscle adaptive response to endurance exercise, but the transcriptome guiding these adaptations in well-trained human skeletal muscle is uncharacterized. In a crossover design, eight cyclists ingested beverages containing protein, carbohydrate and fat (PTN: 0.4, 1.2, 0.2 g/kg, respectively) or isocaloric carbohydrate and fat (CON: 1.6, 0.2 g/kg) at 0 and 1 h following 100 min of cycling. Biopsies of the vastus lateralis were collected at 3 and 48 h following to determine the early and late transcriptome and regulatory signaling responses via microarray and immunoblot. The top gene ontology enriched by PTN were: muscle contraction, extracellular matrix--signaling and structure, and nucleoside, nucleotide, and nucleic acid metabolism (3 and 48 h); developmental processes, immunity, and defense (3 h); glycolysis, lipid and fatty acid metabolism (48 h). The transcriptome was also enriched within axonal guidance, actin cytoskeletal, Ca2+, cAMP, MAPK, and PPAR canonical pathways linking protein nutrition to exercise-stimulated signaling regulating extracellular matrix, slow-myofibril, and metabolic gene expression. At 3 h, PTN attenuated AMPKα1Thr172 phosphorylation but increased mTORC1Ser2448, rps6Ser240/244, and 4E-BP1-γ phosphorylation, suggesting increased translation initiation, while at 48 h AMPKα1Thr172 phosphorylation and PPARG and PPARGC1A expression increased, supporting the late metabolic transcriptome, relative to CON. To conclude, protein feeding following endurance exercise affects signaling associated with cell energy status and translation initiation and the transcriptome involved in skeletal muscle development, slow-myofibril remodeling, immunity and defense, and energy metabolism. Further research should determine the time course and posttranscriptional regulation of this transcriptome and the phenotype responding to chronic postexercise protein feeding.