16 research outputs found

    The IQ Motif is Crucial for Cav1.1 Function

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    Ca2+-dependent modulation via calmodulin, with consensus CaM-binding IQ motif playing a key role, has been documented for most high-voltage-activated Ca2+ channels. The skeletal muscle Cav1.1 also exhibits Ca2+-/CaM-dependent modulation. Here, whole-cell Ca2+ current, Ca2+ transient, and maximal, immobilization-resistant charge movement (Qmax) recordings were obtained from cultured mouse myotubes, to test a role of IQ motif in function of Cav1.1. The effect of introducing mutation (IQ to AA) of IQ motif into Cav1.1 was examined. In dysgenic myotubes expressing YFP-Cav1.1AA, neither Ca2+ currents nor evoked Ca2+ transients were detectable. The loss of Ca2+ current and excitation-contraction coupling did not appear to be a consequence of defective trafficking to the sarcolemma. The Qmax in dysgenic myotubes expressing YFP-Cav1.1AA was similar to that of normal myotubes. These findings suggest that the IQ motif of the Cav1.1 may be an unrecognized site of structural and functional coupling between DHPR and RyR

    Metabolic Phenotype and Adipose Tissue Inflammation in Patients with Chronic Obstructive Pulmonary Disease

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    Potential links between metabolic derangements and adipose tissue (AT) inflammation in patients with chronic obstructive pulmonary disease (COPD) are unexplored. We investigated AT expressions of interleukin (IL)-6, tumor necrosis factor (TNF)-α, CD68 (macrophage cell surface receptor), caspase-3, and Bax, and their relationships to the metabolic phenotype in nine cachectic, 12 normal-weight, 12 overweight, and 11 obese patients with COPD (age 62.3 ± 7.2 years). With increasing body mass index, increases in AT expressions of IL-6, TNF-α, and CD68 were observed (P < .001; P = .005; P < .001, resp.), in association with reduced insulin sensitivity (P < .001). No differences were observed between cachectic and normal-weight patients in AT expressions of inflammatory or proapoptotic markers. Adipose tissue CD68 and TNF-α expressions predicted insulin sensitivity independently of known confounders (P = .005; P = .025; R2 = 0.840). Our results suggest that AT inflammation in obese COPD patients relates to insulin resistance. Cachectic patients remain insulin sensitive, with no AT upregulation of inflammatory or proapoptotic markers

    Hypericin in the Dark: Foe or Ally in Photodynamic Therapy?

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    Photosensitizers (PSs) in photodynamic therapy (PDT) are, in most cases, administered systemically with preferential accumulation in malignant tissues; however, exposure of non-malignant tissues to PS may also be clinically relevant, when PS molecules affect the pro-apoptotic cascade without illumination. Hypericin (Hyp) as PS and its derivatives have long been studied, regarding their photodynamic and photocytotoxic characteristics. Hyp and its derivatives have displayed light-activated antiproliferative and cytotoxic effects in many tumor cell lines without cytotoxicity in the dark. However, light-independent effects of Hyp have emerged. Contrary to the acclaimed Hyp minimal dark cytotoxicity and preferential accumulation in tumor cells, it was recently been shown that non-malignant and malignant cells uptake Hyp at a similar level. In addition, Hyp has displayed light-independent toxicity and anti-proliferative effects in a wide range of concentrations. There are multiple mechanisms underlying Hyp light-independent effects, and we are still missing many details about them. In this paper, we focus on Hyp light-independent effects at several sub-cellular levels—protein distribution and synthesis, organelle ultrastructure and function, and Hyp light-independent effects regarding reactive oxygen species (ROS). We summarize work from our laboratories and that of others to reveal an intricate network of the Hyp light-independent effects. We propose a schematic model of pro- and anti-apoptotic protein dynamics between cell organelles due to Hyp presence without illumination. Based on our model, Hyp can be explored as an adjuvant therapeutic drug in combination with chemo- or radiation cancer therapy

    Endosomes: Guardians Against [Ru(Phen)3]2+ Photo-action In Endothelial Cells During In Vivo pO2 Detection?

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    Phototoxicity is a side-effect of in vitro and in vivo oxygen partial pressure (pO(2)) detection by luminescence lifetime measurement methods. Dichlorotris(1,10-phenanthroline)-ruthenium(II) hydrate ([Ru(Phen)(3)](2+)) is a water soluble pO(2) probe associated with low phototoxicity, which we investigated in vivo in the chick's chorioallantoic membrane (CAM) after intravenous or topical administration and in vitro in normal human coronary artery endothelial cells (HCAEC). In vivo, the level of intravenously injected [Ru(Phen)(3)](2+) decreases within several minutes, whereas the maximum of its biodistribution is observed during the first 2 h after topical application. Both routes are followed by convergence to almost identical "intra/extra-vascular" levels of [Ru(Phen)(3)](2+). In vitro, we observed that [Ru(Phen)(3)](2+) enters cells via endocytosis and is then redistributed. None of the studied conditions induced modification of lysosomal or mitochondrial membranes without illumination. No nuclear accumulation was observed. Without illumination [Ru(Phen)(3)](2+) induces changes in endoplasmic reticulum (ER)-to-Golgi transport. The phototoxic effect of [Ru(Phen)(3)](2+) leads to more marked ultrastructural changes than administration of [Ru(Phen)(3)](2+) only (in the dark). These could lead to disruption of Ca2+ homeostasis accompanied by mitochondrial changes or to changes in secretory pathways. In conclusion, we have demonstrated that the intravenous injection of [Ru(Phen)(3)](2+) into the CAM model mostly leads to extracellular localization of [Ru(Phen)(3)](2+), while its topical application induces intracellular localization. We have shown in vivo that [Ru(Phen)(3)](2+) induces minimal photo-damage after illumination with light doses larger by two orders of magnitude than those used for pO(2) measurements. This low phototoxicity is due to the fact that [Ru(Phen)(3)](2+) enters endothelial cells via endocytosis and is then redistributed towards peroxisomes and other endosomal and secretory vesicles before it is eliminated via exocytosis. Cellular response to [Ru(Phen)(3)](2+), survival or death, depends on its intracellular concentration and oxidation-reduction properties
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