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Connor M Pettem, Jennifer M Briens, David M Janz, Lynn P Weber
Selenium (Se) is considered an essential trace element, involved in important physiological and metabolic functions for all vertebrate species. Fish require dietary concentrations of 0.1-0.5 μg Se/g dry mass (d.m.) to maintain normal physiological and selenoprotein function, however concentrations exceeding 3 μg/g d.m. have been shown to cause toxicity. As Se is reported to have a narrow margin between essentiality and toxicity, there is growing concern surrounding the adverse effects of elevated Se exposure caused by anthropogenic activities...
March 8, 2018: Aquatic Toxicology
Ayushi Guleria, Neha Thukral, Sudhir Chandna
Sf9 lepidopteran insect cells are 100-200 times more radioresistant than mammalian cells. This distinctive feature thus makes them suitable for studies exploring radioprotective molecular mechanisms. It has been established from previous studies of our group that downstream mitochondrial apoptotic signaling pathways in Sf9 cells are quite similar to mammalian cells, implicating the upstream signaling pathways in their extensive radioresistance. In the present study, intracellular and mitochondrial calcium levels remained unaltered in Sf9 cells in response to radiation, in sharp contrast to human (HEK293T) cells...
March 10, 2018: Biochemical and Biophysical Research Communications
Val A Fajardo, John S Mikhaeil, Cameron F Leveille, A Russell Tupling, Paul J LeBlanc
BACKGROUND: An increase in phosphatidylcholine:phosphatidylethanolamine (PC:PE) and a decrease in fatty acyl chain length, monounsaturated:polyunsaturated (MUFA:PUFA) fatty acyl ratio reduces SERCA activity in liposomes and in mouse models of obesity and muscular dystrophy. We have previously shown that maximal SERCA activity is significantly reduced in mechanically overloaded (OVL) plantaris, however, whether changes in PC:PE ratio or fatty acyl composition may contribute to the alterations in maximal SERCA activity remain unknown...
March 13, 2018: Lipids in Health and Disease
Sarah E D Nelson, Kim N Ha, Tata Gopinath, Mara H Exline, Alessandro Mascioni, David D Thomas, Gianluigi Veglia
Approximately, 70% of the Ca2+ ion transport into the sarcoplasmic reticulum is catalyzed by the sarcoplasmic reticulum Ca2+ -ATPase (SERCA), whose activity is endogenously regulated by phospholamban (PLN). PLN comprises a TM inhibitory region and a cytoplasmic regulatory region that harbors a consensus sequence for cAMP-dependent protein kinase (PKA). The inhibitory region binds the ATPase, reducing its apparent Ca2+ binding affinity. β-adrenergic stimulation activates PKA, which phosphorylates PLN at Ser 16, reversing its inhibitory function...
March 1, 2018: Biochimica et Biophysica Acta
Yan G Zhao, Hong Zhang
The ER forms contacts with other endomembrane systems to exchange materials (e.g., calcium and lipids) and also to modulate dynamic organelle processes, including fission, cargo sorting and movement. During autophagosome formation, dynamic contacts between the ER and the phagophore membrane are crucial for phagophore expansion and closure. Little is known about the mechanisms underlying the formation and disassembly of the ER contacts. We found that the ER-localized autophagy protein EPG-3/VMP1 plays an essential role in controlling ER-phagophore dissociation and also the disassembly of ER contacts with LDs, mitochondria and endolysosomes...
March 1, 2018: Autophagy
Edgar Djaha Yoboue, Roberto Sitia, Thomas Simmen
Many cellular redox reactions housed within mitochondria, peroxisomes and the endoplasmic reticulum (ER) generate hydrogen peroxide (H2 O2 ) and other reactive oxygen species (ROS). The contribution of each organelle to the total cellular ROS production is considerable, but varies between cell types and also over time. Redox-regulatory enzymes are thought to assemble at a "redox triangle" formed by mitochondria, peroxisomes and the ER, assembling "redoxosomes" that sense ROS accumulations and redox imbalances...
February 28, 2018: Cell Death & Disease
Megha Amar, Birendra Nath Mallick
Rapid eye movement sleep (REMS) plays an important role in maintaining brain excitability by regulating noradrenaline (NA) level and Na-K ATPase activity. We showed earlier that REMS deprivation (REMSD) associated elevated NA increased neuronal, while decreased glial Na-K ATPase activity. However, our knowledge was insufficient on how the REMSD-associated effect is sustained particularly under chronic condition. Using Neuro-2a cells as a model, we investigated the molecular mechanism of NA-induced increase in mRNA expression of Na-K ATPase subunit and the enzyme activity...
February 22, 2018: Brain Research Bulletin
Renata Gonçalves, Ana Paula Zanatta, Fernanda Carvalho Cavalari, Monica Andressa Wessner do Nascimento, Christelle Delalande-Lecapitaine, Hélène Bouraïma-Lelong, Fátima Regina Mena Barreto Silva
We investigated the acute effect of low concentrations of BPA on calcium influx and the mechanism of action of BPA in this rapid response in the rat testis. BPA increased calcium influx at 1 pM and 1 nM at 300 s of incubation, in a similar manner to that of estradiol. At 1 pM, BPA stimulated calcium influx independently of classical estrogen receptors, consistent with a G-protein coupled receptor. This effect also involves the modulation of ionic channels, such as K+ , TRPV1 and Cl- channels. Furthermore, BPA is able to modulate calcium from intracellular storages by inhibiting SERCA and activating IP3 receptor/Ca2+ channels at the endoplasmic reticulum and activate kinase proteins, such as PKA and PKC...
February 21, 2018: Reproductive Toxicology
Patrycja Kaczara, Bartosz Proniewski, Christopher Lovejoy, Kamil Kuś, Roberto Motterlini, Andrey Y Abramov, Stefan Chlopicki
Carbon monoxide-releasing molecules (CO-RMs) induce nitric oxide (NO) release (which requires NADPH), and Ca2+ -dependent signalling; however, their contribution in mediating endothelial responses is not clear. Here, we studied the effects of CO liberated from CORM-401 on NO production, calcium signalling and pentose phosphate pathway (PPP) activity in human endothelial cell line (EA.hy926). CORM-401 induced NO production and two types of calcium signalling: a peak-like calcium signal and a gradual increase in cytosolic calcium...
February 21, 2018: FEBS Journal
Joseph O Primeau, Gareth P Armanious, M'Lynn E Fisher, Howard S Young
The calcium pump (a.k.a. Ca2+ -ATPase or SERCA) is a membrane transport protein ubiquitously found in the endoplasmic reticulum (ER) of all eukaryotic cells. As a calcium transporter, SERCA maintains the low cytosolic calcium level that enables a vast array of signaling pathways and physiological processes (e.g. synaptic transmission, muscle contraction, fertilization). In muscle cells, SERCA promotes relaxation by pumping calcium ions from the cytosol into the lumen of the sarcoplasmic reticulum (SR), the main storage compartment for intracellular calcium...
2018: Sub-cellular Biochemistry
Wei Zhang, Terunao Takahara, Takuya Achiha, Hideki Shibata, Masatoshi Maki
NFAT is a cytoplasm-localized hyper-phosphorylated transcription factor that is activated through dephosphorylation by calcineurin, a Ca2+ /calmodulin-dependent phosphatase. A non-palindromic NFAT-response element (RE) found in the IL2 promoter region has been commonly used for a Ca2+ -response reporter gene system, but requirement of concomitant activation of AP-1 (Fos/Jun) often complicates the interpretation of obtained results. A new nanoluciferase (NanoLuc) reporter gene containing nine-tandem repeats of a pseudo-palindromic NFAT-RE located upstream of the IL8 promoter was designed to monitor Ca2+ -induced transactivation activity of NFAT in human embryonic kidney (HEK) 293 cells by measuring luciferase activities of NanoLuc and co-expressed firefly luciferase for normalization...
February 18, 2018: International Journal of Molecular Sciences
Ivan Luptak, Aaron L Sverdlov, Marcello Panagia, Fuzhong Qin, David R Pimentel, Dominique Croteau, Deborah A Siwik, Joanne S Ingwall, Markus M Bachschmid, James A Balschi, Wilson S Colucci
Metabolic syndrome is a cluster of obesity-related metabolic abnormalities that lead to metabolic heart disease (MHD) with left ventricular pump dysfunction. Although MHD is thought to be associated with myocardial energetic deficiency, two key questions have not been answered. First, it is not known whether there is a sufficient energy deficit to contribute to pump dysfunction. Second, the basis for the energy deficit is not clear. To address these questions, mice were fed a high fat, high sucrose (HFHS) 'Western' diet to recapitulate the MHD phenotype...
January 31, 2018: Journal of Molecular and Cellular Cardiology
Hongliang Li, Sung Eun Shin, Mi Seon Seo, Jin Ryeol An, Il-Whan Choi, Won-Kyo Jung, Amy L Firth, Dae-Sung Lee, Mi-Jin Yim, Grace Choi, Jeong Min Lee, Sung Hun Na, Won Sun Park
AIM: Considering the clinical efficacy of dapagliflozin in patients with type 2 DM and the pathophysiological relevance of Kv channels for vascular reactivity. We investigate the vasodilatory effect of dapagliflozin and related mechanisms using phenylephrine (Phe)-induced contracted aortic rings. MATERIAL AND METHODS: Arterial tone measurement was performed in aortic smooth muscle. KEY FINDINGS: Application of dapagliflozin induced vasodilation in a concentration-dependent manner...
January 31, 2018: Life Sciences
Peter Boknik, Katharina Drzewiecki, John Eskandar, Ulrich Gergs, Stephanie Grote-Wessels, Larissa Fabritz, Paulus Kirchhof, Frank U Müller, Frank Stümpel, Wilhelm Schmitz, Norbert Zimmermann, Uwe Kirchhefer, Joachim Neumann
Background: Adenosine can be produced in the heart and acts on cardiac adenosine receptors. One of these receptors is the A2A-adenosine receptor (A2A-AR). Methods and Results: To better understand its role in cardiac function, we generated and characterized mice (A2A-TG) which overexpress the human A2A-AR in cardiomyocytes. In isolated atrial preparations from A2A-TG but not from WT, CGS 21680, an A2A-AR agonist, exerted positive inotropic and chronotropic effects. In ventricular preparations from A2A-TG but not WT, CGS 21680 increased the cAMP content and the phosphorylation state of phospholamban and of the inhibitory subunit of troponin in A2A-TG but not WT...
2018: Frontiers in Pharmacology
Nicholas C Vierra, Matthew T Dickerson, Kelli L Jordan, Prasanna K Dadi, Ketaki A Kadare, Molly K Altman, Sarah C Milian, David A Jacobson
OBJECTIVE: Single-cell RNA sequencing studies have revealed that the type-2 diabetes associated two-pore domain K+ (K2P) channel TALK-1 is abundantly expressed in somatostatin-secreting δ-cells. However, a physiological role for TALK-1 in δ-cells remains unknown. We previously determined that in β-cells, K+ flux through endoplasmic reticulum (ER)-localized TALK-1 channels enhances ER Ca2+ leak, modulating Ca2+ handling and insulin secretion. As glucose amplification of islet somatostatin release relies on Ca2+-induced Ca2+ release (CICR) from the δ-cell ER, we investigated whether TALK-1 modulates δ-cell Ca2+ handling and somatostatin secretion...
January 31, 2018: Molecular Metabolism
Stine A Mikkelsen, Peter Vangheluwe, Jens Peter Andersen
The sarco(endo)plasmic reticulum Ca2+-ATPase (SERCA) 2b isoform possesses an extended C terminus (SERCA2b tail) forming an 11th transmembrane (TM) helix, which slows conformational changes of the Ca2+-pump reaction cycle. Here, we report that a Darier disease (DD) mutation of SERCA2b that changes a glutamate to lysine in the cytoplasmic loop between TM8 and TM9 (E917K) relieves these kinetic constraints. We analyzed the effects of this mutation on the overall reaction and the individual partial reactions of the Ca2+ pump compared with the corresponding mutations of the SERCA2a and SERCA1a isoforms lacking the SERCA2b tail...
January 23, 2018: Journal of Biological Chemistry
Sara Damiano, Serena Montagnaro, Maria Valeria Puzio, Lorella Severino, Ugo Pagnini, Marcella Barbarino, Daniele Cesari, Antonio Giordano, Salvatore Florio, Roberto Ciarcia
In clinical practice for the treatment of chronic myeloid leukemia, second generation of tyrosine kinase inhibitors such as Nilotinib (NIL) specific and potent inhibitor of the BCR/ABL kinase and Dasatinib (DAS) a inhibitor of BCR/ABL and Src family kinase were developed to clinically overcome imatinib resistance. In this study we wanted to test the ability of some antioxidants such Resveratrol (RES) or a new recombinant mitochondrial manganese containing superoxide dismutase (rMnSOD) or δ-tocotrienol (δ-TOCO) to interact with DAS and NIL on viability, reactive oxygen species (ROS) production, lipid peroxidation and apoptosis...
January 18, 2018: Journal of Cellular Biochemistry
Neal J Dawson, Sulayman A Lyons, Danielle A Henry, Graham R Scott
AIM: We examined the effects of chronic hypoxia on diaphragm function in high- and low-altitude populations of Peromyscus mice. METHODS: Deer mice (P. maniculatus) native to high altitude and congeneric mice native to low altitude (P. leucopus) were born and raised in captivity to adulthood, and were acclimated to normoxia or hypobaric hypoxia (12 or 9 kPa, simulating hypoxia at 4300 m and 7000 m) for 6-8 weeks. We then measured indices of mitochondrial respiration capacity, force production, and fatigue resistance in the diaphragm...
January 9, 2018: Acta Physiologica
Ki Cheong Park, Seung Won Kim, Jeong Yong Jeon, A Ra Jo, Hye Ji Choi, Jung Min Kim, Hyun Gyu Lee, Yonjung Kim, Gordon B Mills, Sung Hoon Noh, Min Goo Lee, Eun Sung Park, Jae-Ho Cheong
PURPOSE: Cancer cells grow in an unfavorable metabolic milieu in the tumor microenvironment and are constantly exposed to metabolic stress such as chronic nutrient depletion. Cancer stem-like cells (CSCs) are intrinsically resistant to metabolic stress, thereby surviving nutrient insufficiency and driving more malignant tumor progression. In this study, we aimed to demonstrate the potential mechanisms by which CSCs avoid Ca2+-dependent apoptosis during glucose deprivation. EXPERIMENTAL DESIGN: We investigated cell viability and apoptosis under glucose deprivation, performed genome-wide transcriptional profiling of paired CSCs and parental cells, studied the effect of calcium/calmodulin-dependent protein kinase 2 alpha (CaMK2α) gene knockdown, and investigated the role of nuclear factor kappa B (NFκB) in CSCs during time-dependent Ca2+-mediated and glucose deprivation-induced apoptosis...
December 26, 2017: Clinical Cancer Research: An Official Journal of the American Association for Cancer Research
Thomas P Keeley, Richard C M Siow, Ron Jacob, Giovanni E Mann
Unregulated increases in cellular Ca2+ homeostasis are a hallmark of pathophysiological conditions and a key trigger of cell death. Endothelial cells cultured under physiologic O2 conditions (5% O2) exhibit a reduced cytosolic Ca2+ response to stimulation. The mechanism for reduced plateau [Ca2+]i upon stimulation was due to increased sarco/endoplasmic reticulum Ca2+ ATPase (SERCA)-mediated reuptake rather than changes in Ca2+ influx capacity. Agonist-stimulated phosphorylation of the SERCA regulatory protein phospholamban was increased in cells cultured under 5% O2 Elevation of cytosolic and mitochondrial [Ca2+] and cell death after prolonged ionomycin treatment, as a model of Ca2+ overload, were lower when cells were cultured long-term under 5% compared with 18% O2 This protection was abolished by cotreatment with the SERCA inhibitor cyclopiazonic acid...
December 22, 2017: FASEB Journal: Official Publication of the Federation of American Societies for Experimental Biology
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