Examinando por Autor "Kiens, Bente"

Mostrando 1 - 3 de 3
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    Ítem
    mTOR Ser1261 is an AMPK-­ dependent phosphosite in mouse and human skeletal muscle not required for mTORC2 activity
    (John Wiley & Sons Inc., 2025-01-31) Li, Jingwen; Madsen, Agnete B.; Knudsen, Jonas R.; Henríquez-Olguín, Carlos; Persson, Kaspar W.; Li, Zhencheng; Raun, Steffen H.; Li, Tianjiao; Kiens, Bente; Wojtaszewski, Jørgen F. P.; Richter, Erik A.; Nogara, Leonardo; Blaauw, Bert; Ogasawara, Riki; Jensen, Thomas E.
    The kinases AMPK, and mTOR as part of either mTORC1 or mTORC2, are major orchestrators of cellular growth and metabolism. Phosphorylation of mTOR Ser1261 is reportedly stimulated by both insulin and AMPK activation and a regulator of both mTORC1 and mTORC2 activity. Intrigued by the possibilities that Ser1261 might be a convergence point between insulin and AMPK signaling in skeletal muscle, we investigated the regulation and function of this site using a combination of human exercise, transgenic mouse, and cell culture models. Ser1261 phosphorylation on mTOR did not respond to insulin in any of our tested models, but instead responded acutely to contractile activity in human and mouse muscle in an AMPK activity-dependent manner. Contraction-stimulated mTOR Ser1261 phosphorylation in mice was decreased by Raptor muscle knockout (mKO) and increased by Raptor muscle overexpression, yet was not affected by Rictor mKO, suggesting most of Ser1261 phosphorylation occurs within mTORC1 in skeletal muscle. In accordance, HEK293 cells mTOR Ser1261Ala mutation strongly impaired phosphorylation of mTORC1 substrates but not mTORC2 substrates. However, neither mTORC1 nor mTORC2-dependent
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    Ítem
    Revisiting insulin-stimulated hydrogen peroxide dynamics reveals a cytosolic reductive shift in skeletal muscle
    (Elsevier, 2025-04-25) Henríquez-Olguín, Carlos; Gallero, Samantha; Reddy, Anita; Persson, Kaspar W.; Schlabs, Farina L.; Voldstedlund, Christian T.; Valentinaviciute, Gintare; Meneses-Valdés, Roberto; Sigvardsen, Casper M.; Kiens, Bente; Chouchani, Edward T.; Richter, Erik A.; Jensen, Thomas E.
    The intracellular redox state is crucial for insulin responses in peripheral tissues. Despite the longstanding belief that insulin signaling increases hydrogen peroxide (H2O2) production leading to reversible oxidation of cysteine thiols, evidence is inconsistent and rarely involves human tissues. In this study, we systematically investigated insulin-dependent changes in subcellular H2O2 levels and reversible cysteine modifications across mouse and human skeletal muscle models. Utilizing advanced redox tools including genetically encoded H2O2 sensors and non-reducing immunoblotting we consistently observed no increase in subcellular H2O2 levels following insulin stimulation. Instead, stoichiometric cysteine proteome analyses revealed a selective pro-reductive shift in cysteine modifications affecting insulin transduction related proteins, including Cys179 on GSK3β and Cys416 on Ras and Rab Interactor 2 (RIN2). Our findings challenge the prevailing notion that insulin promotes H2O2 generation in skeletal muscle and suggest that an insulin-stimulated pro-reductive shift modulates certain aspects of insulin signal transduction.
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    Ítem
    Skeletal muscle Rac1 mediates exercise training adaptations towards muscle glycogen resynthesis and protein synthesis
    (Elsevier, 2025-08-28) Raun, Steffen H.; Henriquez-Olguín, Carlos; Frank, Emma; Schlabs, Farina; Hahn, Nanna Just; Roland Knudsen, Jonas; Ali, Mona S.; Andersen, Nicoline R.; Møller, Lisbeth L.V.; Davey, Jonathan; Qian, Hongwei; Coelho, Ana; Carl, Christian S.; Voldstedlund, Christian T.; Kiens, Bente; Holmdahl, Rikard; Gregorevic, Paul; Jensen, Thomas E.; Deshmukh, Atul S.; Richter, Erik A.; Sylow, Lykke
    Long-term exercise training elicits tremendous health benefits; however, the molecular understanding is incomplete and identifying therapeutic targets has been challenging. Rho GTPases are among the most regulated groups of proteins after exercise in human skeletal muscle, yet, unexplored candidates for mediating the effects of exercise training. We found that the Rho GTPase Rac1 was activated acutely after multiple exercise modalities in human skeletal muscle. Loss of Rac1 specifically in muscle attenuated contraction-induced muscle protein synthesis, diminished improvements in running capacity, and prevented muscle hypertrophy after exercise training in mice. Additionally, Ncf1* mice revealed that Rac1 regulated glycogen resynthesis via a NOX2-dependent mechanism. Molecularly, Rac1 was required for contraction-induced p38MAPK signaling towards HSP27, MNK1, and CREB phosphorylation. In vivo muscle-targeted overexpression of a hyperactive Rac1-mutant elevated reactive oxidant species production during exercise but did not affect muscle mass. Using mass spectrometry-based proteomics, we found that loss or gain of Rac1 muscle protein affected pathways related to cytoskeleton organization, muscle adaptation, and large ribosomal subunits. Thus, skeletal muscle Rac1 mediates both molecular and functional adaptation to exercise training.