Biology subjects

Holmdahl, R.

Publications and source records attributed to Holmdahl, R..

3 recordsLinked to original sources

bioRxiv2019

Functional and signaling characterization of the neutrophil FPR2 selective agonist Act-389949

Despite the steadily increased numbers of formyl peptide receptor (FPR) ligands identified over the years, few have been characterized in studies using animal disease models and even less have entered clinical trials in human subjects. A small-molecule compound, Act-389949, was however recently tested in a phase I clinical trial and found to be safe and well tolerated in healthy human subjects. The desired anti-inflammatory property of Act-389949 was proposed to be mediated through FPR2, one of the FPRs expressed in neutrophils, but no basic characterization was included in the study. To gain more insights into FPR2 recognition of this first-in-class compound for future utility of the agonist, we have in this study determined the receptor preference and down-stream signaling characteristics induced by Act-389949 in human blood neutrophils isolated from healthy donors. Our data demonstrate that Act-389949 is an agonist for FPR2 that triggers functional/signaling repertoires comparable to what has been earlier described for other FPR2 agonists, including neutrophil chemotaxis, granule mobilization and activation of the NADPH-oxidase. In fact, Act-389949 was found to be as potent as the prototype FPR2 peptide agonist WKYMVM and had the advantage of being resistant to oxidation by the MPO-H2O2-halide derived oxidants, as compared to the sensitive WKYMVM. The down-stream signals generated by Act-389949 include an FPR2-dependent and Gq-independent transient rise in intracellular Ca2+ and recruitment of {beta}-arrestin. In summary, our data show that Act-389949 serves as an excellent tool-compound for further dissection of FPR2-regulated activities in vitro and in vivo. Potent and stable FPR ligands such as Act-389949 may therefore be used to develop the next generation of FPR signaling regulating anti-inflammatory therapeutics.

pharmacology and toxicology↗

bioRxiv2019

NADPH-oxidase 2 is required for molecular adaptations to high-intensity interval training in skeletal muscle.

Objective: Reactive oxygen species (ROS) have been proposed as signaling molecules mediating exercise training adaptation, but the ROS source has remained unclear. This study aimed to investigate the requirement for NADPH oxidase (NOX)2-dependent redox changes induced by acute and long-term high-intensity interval training (HIIT) in skeletal muscle in a mouse model lacking functional NOX2 complex due to deficient p47phox (Ncf1) subunit expression (ncf1* mutation). Methods: HIIT was investigated after an acute bout of exercise and after a chronic intervention (3x week for 6 weeks) in wildtype (WT) vs. NOX2 activity-deficient (ncf1*) mice. NOX2 activation during HIIT was measured using a genetically-encoded biosensor. Immunoblotting and single-fiber staining were performed to measure classical exercise-training responsive endpoints in skeletal muscle. Results: A single bout of HIIT increased NOX2 activity measured using electroporated p47roGFP oxidation immediately after exercise but not 1h after exercise. After a 6-week of HIIT regime, improvements in maximal running capacity and some muscle training-markers responded less to HIIT in the ncf1* mice compared to WT, including superoxide dismutase (SOD)2, catalase, hexokinase II (HK II), pyruvate dehydrogenase (PDH) and protein markers of mitochondrial oxidative phosphorylation complexes. Strikingly, HIIT-training increased mitochondrial network area and decreased fragmentation in WT mice only. Conclusion: This study provided evidence that HIIT exercise activates NOX2 complex in skeletal muscle and that the presence of functional NOX2 is required for specific skeletal muscle adaptations to HIIT relating to antioxidant defense, glucose metabolism, and mitochondria.

physiology↗

bioRxiv2019

Exercise-stimulated muscle ROS production and glucose uptake requires NADPH oxidase 2

Reactive oxygen species (ROS) act as intracellular compartmentalized second messengers mediating metabolic stress-adaptation. In skeletal muscle fibers, ROS have been suggested to stimulate glucose transporter 4 (GLUT4)-dependent glucose transport during artificially evoked contraction ex vivo but whether myocellular ROS production is stimulated by in vivo exercise to control metabolism is unclear. Here, we combined exercise in humans and mice with fluorescent dyes, genetically-encoded biosensors, and NADPH oxidase 2 (NOX2) loss-of-function models to demonstrate that NOX2 is the main source of cytosolic ROS during moderate-intensity exercise in skeletal muscle. Furthermore, two NOX2 loss-of-function mouse models lacking either p47phox or Rac1 presented striking phenotypic similarities, including greatly reduced exercise-stimulated glucose uptake and GLUT4 translocation. These findings indicate that NOX2 is a major myocellular ROS source regulating glucose transport capacity during moderate-intensity exercise.

physiology↗