Dysregulation of skeletal muscle morphology and metabolism is associated with chronic diseases such as obesity and type 2 diabetes. The enzyme glycogen synthase kinase 3 (GSK3) is highly involved in skeletal muscle physiology and metabolism, acting as a negative regulator of muscle size, strength, adaptive thermogenesis, and glucose homeostasis. Correspondingly, we have shown that partial knockdown (∼40%) of GSK3 specifically in skeletal muscle increases lean mass, reduces fat mass, and activates muscle-based adaptive thermogenesis via sarco(endo)plasmic reticulum Ca (SERCA) uncoupling in male mice.
View Article and Find Full Text PDFHereditary leiomyomatosis and renal cell cancer (HLRCC) is a cancer syndrome caused by inactivating germline mutations in fumarate hydratase (FH) and subsequent accumulation of fumarate. Fumarate accumulation leads to profound epigenetic changes and the activation of an anti-oxidant response via nuclear translocation of the transcription factor NRF2. The extent to which chromatin remodeling shapes this anti-oxidant response is currently unknown.
View Article and Find Full Text PDFSarco(endo)plasmic reticulum Ca-ATPase (SERCA) uncoupling in skeletal muscle and mitochondrial uncoupling via uncoupling protein 1 (UCP1) in brown/beige adipose tissue are two mechanisms implicated in energy expenditure. Here, we investigated the effects of glycogen synthase kinase 3 (GSK3) inhibition via lithium chloride (LiCl) treatment on SERCA uncoupling in skeletal muscle and UCP1 expression in adipose. C2C12 and 3T3-L1 cells treated with LiCl had increased SERCA uncoupling and UCP1 protein levels, respectively, ultimately raising cellular respiration; however, this was only observed when LiCl treatment occurred throughout differentiation.
View Article and Find Full Text PDFBackground: Tissue hypoxia is a key feature of several endemic hepatic diseases, including alcoholic and non-alcoholic fatty liver disease, and organ failure. Hypoxia imposes a severe metabolic challenge on the liver, potentially disrupting its capacity to carry out essential functions including fuel storage and the integration of lipid metabolism at the whole-body level. Mitochondrial respiratory function is understood to be critical in mediating the hepatic hypoxic response, yet the time-dependent nature of this response and the role of the respiratory chain in this remain unclear.
View Article and Find Full Text PDFCalcineurin is a Ca/calmodulin (CaM)-dependent phosphatase that plays a critical role in promoting the slow fiber phenotype and myoblast fusion in skeletal muscle, thereby making calcineurin an attractive cellular target for enhancing fatigue resistance, muscle metabolism, and muscle repair. Neurogranin (Ng) is a CaM-binding protein thought to be expressed solely in brain and neurons, where it inhibits calcineurin signaling by sequestering CaM, thus lowering its cellular availability. Here, we demonstrate for the first time the expression of Ng protein and in mammalian skeletal muscle.
View Article and Find Full Text PDFResveratrol (RES) is a polyphenol produced by certain plant species that has been well studied due to its ability to slow the growth of cancer cells. In numerous cell types and tissues, RES has been demonstrated to promote mitochondrial biogenesis, fusion, and oxidative phosphorylation. The present study investigated the interaction between RES's effects on growth and metabolism in PC3 prostate cancer cells, and demonstrated that RES-mediated growth inhibition is only observed under conditions in which a metabolic shift from glucose fermentation to mitochondrial respiration can occur.
View Article and Find Full Text PDFThe production and use of multi-modal imaging agents is on the rise. The vast majority of these imaging agents are limited to a single length scale for the agent (e.g.
View Article and Find Full Text PDFMost mammalian tissue cells experience oxygen partial pressures equivalent to 1-6% O (i.e., physioxia).
View Article and Find Full Text PDFDysregulated mitochondrial function is associated with the pathology of a wide range of diseases including renal disease and cancer. Thus, investigating regulators of mitochondrial function is of particular interest. Previous work has shown that the von Hippel-Lindau tumor suppressor protein (pVHL) regulates mitochondrial biogenesis and respiratory chain function.
View Article and Find Full Text PDFSome adult vertebrate species, such as newts, axolotls and zebrafish, have the ability to regenerate their central nervous system (CNS). However, the factors that establish a permissive CNS environment for correct morphological and functional regeneration in these species are not well understood. Recent evidence supports a role for retinoid signaling in the intrinsic ability of neurons, in these regeneration-competent species, to regrow after CNS injury.
View Article and Find Full Text PDFBiochem Biophys Res Commun
November 2017
Although oxygen levels in the extracellular space of most mammalian tissues are just a few percent, under standard cell culture conditions they are not regulated and are often substantially higher. Some cellular sources of reactive oxygen species, like NADPH oxidase 4, are sensitive to oxygen levels in the range between 'normal' physiological (typically 1-5%) and standard cell culture (up to 18%). Hydrogen peroxide in particular participates in signal transduction pathways via protein redox modifications, so the potential increase in its production under standard cell culture conditions is important to understand.
View Article and Find Full Text PDFMitochondria exist in a dynamic cycle of fusion and fission whose balance directly influences the morphology of the 'mitochondrial network', a term that encompasses the branched, reticular structure of fused mitochondria as well as the separate, punctate individual organelles within a eukaryotic cell. Over the past decade, the significance of the mitochondrial network has been increasingly appreciated, motivating the development of various approaches to analyze it. Here, we describe the Mitochondrial Network Analysis (MiNA) toolset, a relatively simple pair of macros making use of existing ImageJ plug-ins, allowing for semi-automated analysis of mitochondrial networks in cultured mammalian cells.
View Article and Find Full Text PDFBiochem Biophys Res Commun
April 2017
Resveratrol (RES) is a plant-derived stilbene associated with a wide range of health benefits. Mitochondria are a key downstream target of RES, and in some cell types RES promotes mitochondrial biogenesis, altered cellular redox status, and a shift toward oxidative metabolism. Mitochondria exist as a dynamic network that continually remodels via fusion and fission processes, and the extent of fusion is related to cellular redox status and metabolism.
View Article and Find Full Text PDFA variety of mitochondria-targeted small molecules have been invented to manipulate mitochondrial redox activities and improve function in certain disease states. 3-Hydroxypropyl-triphenylphosphonium-conjugated imidazole-substituted oleic acid (TPP-IOA) was developed as a specific inhibitor of cytochrome c peroxidase activity that inhibits apoptosis by preventing cardiolipin oxidation and cytochrome c release to the cytosol. Here we evaluate the effects of TPP-IOA on oxidative phosphorylation in isolated mitochondria and on mitochondrial function in live cells.
View Article and Find Full Text PDFBODIPY fluorophores bearing azide or terminal alkyne functions were conjugated with glycans modified with terminal alkyne or azido through the Cu(I)-catalyzed 1,3-dipolar azide-alkyne cycloaddition (CuAAC) chemistry under microwave heating while these reactions did not proceed when heated in an oil-bath. The BODIPY-glycan conjugate product 8a undergoes self-assembly into liposomes when hydrated. Formation of liposomes was confirmed by both bright field and confocal microscopy.
View Article and Find Full Text PDFSince its inception more than four decades ago, the Mitochondrial Free Radical Theory of Aging (MFRTA) has served as a touchstone for research into the biology of aging. The MFRTA suggests that oxidative damage to cellular macromolecules caused by reactive oxygen species (ROS) originating from mitochondria accumulates in cells over an animal's lifespan and eventually leads to the dysfunction and failure that characterizes aging. A central prediction of the theory is that the ability to ameliorate or slow this process should be associated with a slowed rate of aging and thus increased lifespan.
View Article and Find Full Text PDFComp Biochem Physiol A Mol Integr Physiol
July 2012
Within mammalian species, standard metabolic rate (SMR) increases disproportionately with body mass (Mb), such that the mass-specific SMR correlates negatively with Mb. This phenomenon can be explained in part by reduced cellular metabolic rates in larger species. To better understand the cause(s) of this cellular metabolic rate allometry we have used an ex vivo approach to isolate and identify potential contributors.
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