Lima, P. D. | bioRxiv Science

bioRxiv2024

Platelet bioenergetics correlate with skeletal muscle metabolism in C57BL/6J mice

Skeletal muscle insulin resistance is a key step in progression of cardiometabolic disease, and impaired mitochondrial bioenergetics has been implicated. However, mitochondrial bioenergetic research in skeletal muscle is limited by the need for muscle biopsies. We sought to determine if platelet bioenergetics could be used as a minimally invasive surrogate for skeletal muscle bioenergetics. Multiple parameters of mitochondrial respiration, measured by high resolution respirometry, correlated between platelets and gastrocnemius muscle in mice. We propose the coupling state of platelet mitochondria reflects that of skeletal muscle in mice, providing a foundation for future research on using platelets as a liquid biopsy for muscle mitochondrial health in cardiometabolic disease, offering early insights into muscle metabolism to enhance clinical biomarker implementation. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=158 SRC="FIGDIR/small/626404v1_ufig1.gif" ALT="Figure 1"> View larger version (26K): org.highwire.dtl.DTLVardef@1f65c4aorg.highwire.dtl.DTLVardef@125318borg.highwire.dtl.DTLVardef@d7bf1dorg.highwire.dtl.DTLVardef@442926_HPS_FORMAT_FIGEXP M_FIG C_FIG

molecular biology↗

bioRxiv2023

Efficacy of Drpitor1a, a Dynamin-Related Protein 1 inhibitor, in Pulmonary Arterial Hypertension

RationaleDynamin-related protein 1 (Drp1), a large GTPase, mediates mitochondrial fission. Increased Drp1-mediated fission permits accelerated mitosis, contributing to hyperproliferation of pulmonary artery smooth muscle cells (PASMC), which characterizes pulmonary arterial hypertension (PAH). We developed a Drp1 inhibitor, Drpitor1a, and tested its ability to regress PAH. ObjectivesAssess Drpitor1as efficacy and toxicity in: a)normal and PAH human PASMC (hPASMC); b)normal rats versus rats with established monocrotaline (MCT)-induced PAH. MethodsDrpitor1as effects on recombinant and endogenous Drp1-GTPase activity, mitochondrial fission, and cell proliferation were studied in hPASMCs (normal=3; PAH=5). Drpitor1as pharmacokinetics and tissue concentrations were measured (n=3 rats/sex). In a pilot study (n=3-4/sex/dose), Drpitor1a (1mg/kg/48-hours, intravenous) reduced adverse PA remodeling only in females. Consequently, we compared Drpitor1a to vehicle in normal (n=6 versus 8) and MCT-PAH (n=9 and 11) females, respectively. Drpitor1a treatment began 17-days post-MCT with echocardiography and cardiac catheterization performed 28-29 days post-MCT. ResultsDrpitor1a inhibited recombinant and endogenous Drp1 GTPase activity, which was increased in PAH hPASMC. Drpitor1a inhibited mitochondrial fission and proliferation and induced apoptosis, in PAH hPASMC but not normal hPASMC. Drpitor1a tissue levels were higher in female versus male RVs. In MCT-PAH females, Drpitor1a regressed PA obstruction, lowered pulmonary vascular resistance, and improved RV function, without hematologic, renal, or hepatic toxicity. ConclusionsDrpitor1a inhibits Drp1 GTPase, reduces mitochondrial fission, and inhibits cell proliferation in PAH hPASMC. Drpitor1a caused no toxicity in MCT-PAH and had no significant effect on normal rats or hPASMCs. Drpitor1a is a potential PAH therapeutic which displays an interesting therapeutic sexual dimorphism.

pharmacology and toxicology↗