scholarly journals Anion Transport in Heart

2000 ◽  
Vol 80 (1) ◽  
pp. 31-81 ◽  
Author(s):  
Joseph R. Hume ◽  
Dayue Duan ◽  
Mei Lin Collier ◽  
Jun Yamazaki ◽  
Burton Horowitz
Keyword(s):  
Protein Kinase ◽  
Anion Exchange ◽  
Mammalian Cells ◽  
Anion Transport ◽  
Transport Proteins ◽  
Cardiac Cells ◽  
Transport Processes ◽  
Anion Channels ◽  
Voltage Dependent Anion Channel ◽  
Intracellular Membranes

Anion transport proteins in mammalian cells participate in a wide variety of cell and intracellular organelle functions, including regulation of electrical activity, pH, volume, and the transport of osmolites and metabolites, and may even play a role in the control of immunological responses, cell migration, cell proliferation, and differentiation. Although significant progress over the past decade has been achieved in understanding electrogenic and electroneutral anion transport proteins in sarcolemmal and intracellular membranes, information on the molecular nature and physiological significance of many of these proteins, especially in the heart, is incomplete. Functional and molecular studies presently suggest that four primary types of sarcolemmal anion channels are expressed in cardiac cells: channels regulated by protein kinase A (PKA), protein kinase C, and purinergic receptors ( I Cl.PKA); channels regulated by changes in cell volume ( I Cl.vol); channels activated by intracellular Ca2+ ( I Cl.Ca); and inwardly rectifying anion channels ( I Cl.ir). In most animal species, I Cl.PKA is due to expression of a cardiac isoform of the epithelial cystic fibrosis transmembrane conductance regulator Cl− channel. New molecular candidates responsible for I Cl.vol, I Cl.Ca, and I Cl.ir(ClC-3, CLCA1, and ClC-2, respectively) have recently been identified and are presently being evaluated. Two isoforms of the band 3 anion exchange protein, originally characterized in erythrocytes, are responsible for Cl−/HCO3 − exchange, and at least two members of a large vertebrate family of electroneutral cotransporters (ENCC1 and ENCC3) are responsible for Na+-dependent Cl− cotransport in heart. A 223-amino acid protein in the outer mitochondrial membrane of most eukaryotic cells comprises a voltage-dependent anion channel. The molecular entities responsible for other types of electroneutral anion exchange or Cl− conductances in intracellular membranes of the sarcoplasmic reticulum or nucleus are unknown. Evidence of cardiac expression of up to five additional members of the ClC gene family suggest a rich new variety of molecular candidates that may underlie existing or novel Cl− channel subtypes in sarcolemmal and intracellular membranes. The application of modern molecular biological and genetic approaches to the study of anion transport proteins during the next decade holds exciting promise for eventually revealing the actual physiological, pathophysiological, and clinical significance of these unique transport processes in cardiac and other mammalian cells.

Bicarbonate transport proteins

2002 ◽  
Vol 80 (5) ◽  
pp. 483-497 ◽  
Author(s):  
Deborah Sterling ◽  
Joseph R Casey
Keyword(s):  
Carbonic Anhydrase ◽  
Sodium Bicarbonate ◽  
Anion Exchange ◽  
Mammalian Cells ◽  
Ph Regulation ◽  
Transport Proteins ◽  
Bicarbonate Transport ◽  
Transport Mechanisms ◽  
Bicarbonate Transporter ◽  
Bicarbonate Transporters

Bicarbonate is not freely permeable to membranes. Yet, bicarbonate must be moved across membranes, as part of CO2 metabolism and to regulate cell pH. Mammalian cells ubiquitously express bicarbonate transport proteins to facilitate the transmembrane bicarbonate flux. These bicarbonate transporters, which function by different transport mechanisms, together catalyse transmembrane bicarbonate movement. Recent advances have allowed the identification of several new bicarbonate transporter genes. Bicarbonate transporters cluster into two separate families: (i) the anion exachanger (AE) family of Cl–/HCO[Formula: see text] exchangers is related in sequence to the NBC family of Na+/HCO[Formula: see text] cotransporters and the Na+-dependent Cl–/HCO[Formula: see text] exchangers and (ii) some members of the SLC26a family of sulfate transporters will also transport bicarbonate but are not related in sequence to the AE/NBC family of transporters. This review summarizes our understanding of the mammalian bicarbonate transporter superfamily.Key words: bicarbonate transport, anion exchange, pH regulation, sodium/bicarbonate co-transport, chloride/bicarborate exchange, carbonic anhydrase.

Recent advances in the molecular biology of nucleoside transporters of mammalian cells

1998 ◽  
Vol 76 (5) ◽  
pp. 761-770 ◽  
Author(s):  
Carol E Cass ◽  
James D Young ◽  
Stephen A Baldwin
Keyword(s):  
Molecular Biology ◽  
Mammalian Cells ◽  
Cell Types ◽  
Functional Expression ◽  
Transport Proteins ◽  
Transport Processes ◽  
Nucleoside Transport ◽  
Nucleoside Transporter ◽  
Protein Families ◽  
Public Data

Nucleosides are hydrophilic molecules and require specialized transport proteins for permeation of cell membranes. There are two types of nucleoside transport processes: equilibrative bidirectional processes driven by chemical gradients and inwardly directed concentrative processes driven by the sodium electrochemical gradient. The equilibrative nucleoside transport processes (es, ei) are found in most mammalian cell types, whereas the concentrative nucleoside transport processes (cit, cif, cib, csg, cs) are present primarily in specialized epithelia. Using a variety of cloning strategies and functional expression in oocytes of Xenopus laevis, we have isolated and characterized cDNAs encoding the rat and human nucleoside transporter proteins of the four major nucleoside transport processes of mammalian cells (es, ei, cit, cif). From the sequence relationships of these proteins with each other and with sequences in the public data bases, we have concluded that the equilibrative and concentrative nucleoside transport processes are mediated by members of two previously unrecognized groups of integral membrane proteins, which we have designated the equilibrative nucleoside transporter (ENT) and the concentrative nucleoside transporter (CNT) protein families. This review summarizes the current state of knowledge in the molecular biology of the ENT and CNT protein families, focusing on the characteristics of the four human (h) and rat (r) nucleoside transport proteins (r/hENT1, r/hENT2, r/hCNT1, r/hCNT2).Key words: nucleoside transporter, equilibrative, concentrative, ENT, CNT.

Early signalling events of autophagy

2013 ◽  
Vol 55 ◽  
pp. 1-15 ◽  
Author(s):  
Laura E. Gallagher ◽  
Edmond Y.W. Chan
Keyword(s):  
Protein Kinase ◽  
Focal Adhesion Kinase ◽  
Focal Adhesion ◽  
Mammalian Cells ◽  
Mammalian Target Of Rapamycin ◽  
Interacting Protein ◽  
The Core ◽  
Autophagy Gene ◽  
Autophagy Induction ◽  
Cellular Pathways

Autophagy is a conserved cellular degradative process important for cellular homoeostasis and survival. An early committal step during the initiation of autophagy requires the actions of a protein kinase called ATG1 (autophagy gene 1). In mammalian cells, ATG1 is represented by ULK1 (uncoordinated-51-like kinase 1), which relies on its essential regulatory cofactors mATG13, FIP200 (focal adhesion kinase family-interacting protein 200 kDa) and ATG101. Much evidence indicates that mTORC1 [mechanistic (also known as mammalian) target of rapamycin complex 1] signals downstream to the ULK1 complex to negatively regulate autophagy. In this chapter, we discuss our understanding on how the mTORC1–ULK1 signalling axis drives the initial steps of autophagy induction. We conclude with a summary of our growing appreciation of the additional cellular pathways that interconnect with the core mTORC1–ULK1 signalling module.

scholarly journals Control of PKR Protein Kinase by Hepatitis C Virus Nonstructural 5A Protein: Molecular Mechanisms of Kinase Regulation

1998 ◽  
Vol 18 (9) ◽  
pp. 5208-5218 ◽  
Author(s):  
Michael Gale ◽  
Collin M. Blakely ◽  
Bart Kwieciszewski ◽  
Seng-Lai Tan ◽  
Michelle Dossett ◽  
...  
Keyword(s):  
Hepatitis C Virus ◽  
Hepatitis C ◽  
Protein Kinase ◽  
Mammalian Cells ◽  
Molecular Mechanisms ◽  
Functional Assay ◽  
Binding Region ◽  
Dimerization Domain ◽  
Antiviral Effects

ABSTRACT The PKR protein kinase is a critical component of the cellular antiviral and antiproliferative responses induced by interferons. Recent evidence indicates that the nonstructural 5A (NS5A) protein of hepatitis C virus (HCV) can repress PKR function in vivo, possibly allowing HCV to escape the antiviral effects of interferon. NS5A presents a unique tool by which to study the molecular mechanisms of PKR regulation in that mutations within a region of NS5A, termed the interferon sensitivity-determining region (ISDR), are associated with sensitivity of HCV to the antiviral effects of interferon. In this study, we investigated the mechanisms of NS5A-mediated PKR regulation and the effect of ISDR mutations on this regulatory process. We observed that the NS5A ISDR, though necessary, was not sufficient for PKR interactions; we found that an additional 26 amino acids (aa) carboxyl to the ISDR were required for NS5A-PKR complex formation. Conversely, we localized NS5A binding to within PKR aa 244 to 296, recently recognized as a PKR dimerization domain. Consistent with this observation, we found that NS5A from interferon-resistant HCV genotype 1b disrupted kinase dimerization in vivo. NS5A-mediated disruption of PKR dimerization resulted in repression of PKR function and inhibition of PKR-mediated eIF-2α phosphorylation. Introduction of multiple ISDR mutations abrogated the ability of NS5A to bind to PKR in mammalian cells and to inhibit PKR in a yeast functional assay. These results indicate that mutations within the PKR-binding region of NS5A, including those within the ISDR, can disrupt the NS5A-PKR interaction, possibly rendering HCV sensitive to the antiviral effects of interferon. We propose a model of PKR regulation by NS5A which may have implications for therapeutic strategies against HCV.

scholarly journals High performance anion exchange ionomer for anion exchange membrane fuel cells

RSC Advances ◽  
2017 ◽  
Vol 7 (31) ◽  
pp. 19153-19161 ◽  
Author(s):  
Xueqiang Gao ◽  
Hongmei Yu ◽  
Jia Jia ◽  
Jinkai Hao ◽  
Feng Xie ◽  
...  
Keyword(s):  
Fuel Cells ◽  
Fuel Cell ◽  
Anion Exchange ◽  
High Performance ◽  
Catalyst Layer ◽  
Anion Transport ◽  
Anion Exchange Membrane ◽  
Exchange Membrane

The anion exchange ionomer incorporated into the electrodes of an anion exchange membrane fuel cell (AEMFC) enhances anion transport in the catalyst layer of the electrode, and thus improves performance and durability of the AEMFC.

scholarly journals Cell Volume-Activated and Volume-Correlated Anion Channels in Mammalian Cells: Their Biophysical, Molecular, and Pharmacological Properties

2018 ◽  
Vol 71 (1) ◽  
pp. 49-88 ◽  
Author(s):  
Yasunobu Okada ◽  
Toshiaki Okada ◽  
Kaori Sato-Numata ◽  
Md. Rafiqul Islam ◽  
Yuhko Ando-Akatsuka ◽  
...  
Keyword(s):  
Cell Volume ◽  
Mammalian Cells ◽  
Pharmacological Properties ◽  
Anion Channels

Genetic analysis of intracellular aminoglycerophospholipid traffic

2004 ◽  
Vol 82 (1) ◽  
pp. 156-169 ◽  
Author(s):  
Dennis R Voelker
Keyword(s):  
Genetic Analysis ◽  
Mammalian Cells ◽  
Molecular Genetic ◽  
Family Members ◽  
Molecular Genetic Analysis ◽  
Transport Processes ◽  
Membrane Biogenesis ◽  
Independent Manner ◽  
Multiple Genes ◽  
Vacuolar Protein

Inter- and intramembrane phospholipid transport processes are central features of membrane biogenesis and homeostasis. Relatively recent successes in the molecular genetic analysis of aminoglycerophospholipid transport processes in both yeast and mammalian cells are now providing important new information defining specific protein and lipid components that participate in these reactions. Studies focused on phosphatidylserine (PtdSer) transport to the mitochondria reveal that the process is regulated by ubiquitination. In addition, a specific mutation disrupts PtdSer transport between mitochondrial membranes. Analysis of PtdSer transport from the endoplasmic reticulum to the locus of PtdSer decarboxylase 2 demonstrates the requirement for a phosphatidylinositol-4-kinase, a phosphatidylinositol-binding protein, and the C2 domain of the decarboxylase. Examination of NBD-phosphatidylcholine transport demonstrates the involvement of the prevacuolar compartment and a requirement for multiple genes involved in regulating vacuolar protein sorting for transport of the lipid to the vacuole. In intramembrane transport, multiple genes are now identified including those encoding multidrug resistant protein family members, DNF family members, ATP binding cassette transporters, and pleiotropic drug resistance family members. The scramblase family constitutes a collection of putative transmembrane transporters that function in an ATP-independent manner. The genetic analysis of lipid traffic is uncovering new molecules involved in all aspects of the regulation and execution of the transport steps and also providing essential tools to critically test the involvement of numerous candidate molecules.Key words: lipid transport, lipid sorting, membrane biogenesis, organelles, flippase.

Regulation of Na+ pump expression by vascular smooth muscle cells

2001 ◽  
Vol 280 (4) ◽  
pp. H1869-H1874 ◽  
Author(s):  
Aslihan Aydemir-Koksoy ◽  
Julius C. Allen
Keyword(s):  
Smooth Muscle ◽  
Vascular Smooth Muscle ◽  
Smooth Muscle Cells ◽  
Vascular Smooth Muscle Cells ◽  
Mammalian Cells ◽  
Muscle Cells ◽  
Transport Processes ◽  
Western Blots ◽  
Cytoplasmic Transport ◽  
Low K

The Na+ pump and its regulation is important for maintaining membrane potential and transmembrane Na+gradient in all mammalian cells and thus is essential for cell survival and function. Vascular smooth muscle cells (VSMC) have a relatively low number of pump sites on their membrane compared with other cells. We wished to determine the mechanisms for regulating the number of pump sites in these cells. We used canine saphenous vein VSMC cultured in 10% serum and passaged one time. These cells were subcultured in 5% serum media with low K+ (1 mM vs. control of 5 mM), and their pump expression was assessed. These VSMC upregulated their pump sites as early as 4 h after treatment (measured by [3H]ouabain binding). At this early time point, there was no detectable increase in protein expression of either α1- or β1-subunits of the pump shown by Western blots. When the cells were treated with the phosphoinositide 3-kinase (PI-3-K) inhibitor LY-294002 (which is known to inhibit cytoplasmic transport processes) in low-K+ media, the pump site upregulation was inhibited. These data suggest that the low-K+-induced upregulation of Na+ pump number can occur by translocation of preformed pumps from intracellular stores.

Protein Kinase C-Mediated Desmin Phosphorylation is Related to Myofibril Disarray in Cardiomyopathic Hamster Heart1

2002 ◽  
Vol 227 (11) ◽  
pp. 1039-1046 ◽  
Author(s):  
Xupei Huang ◽  
Jian Li ◽  
Dalton Foster ◽  
Sharon L. Lemanski ◽  
Dipak K. Dube ◽  
...  
Keyword(s):  
Protein Kinase C ◽  
Protein Kinase ◽  
Premature Death ◽  
Cardiac Cells ◽  
Immunogold Electron Microscopy ◽  
Intermediate Filament Protein ◽  
Kinase C ◽  
Hamster Strain ◽  
Significant Difference ◽  
Hereditary Cardiomyopathy

The cardiomyopathic (CM) Syrian golden hamster (strain UM-X7.1) exhibits a hereditary cardiomyopathy, which causes premature death resulting from congestive heart failure. The CM animals show extensive cardiac myofibril disarray and myocardial calcium overload. The present study has been undertaken to examine the role of desmin phosphorylation in myofibril disarray observed in CM hearts. The data from skinned myofibril protein phosphorylation assays have shown that desmin can be phosphorylated by protein kinase C (PKC). There is no significant difference in the content of desmin between CM and control hamster hearts. However, the desmin from CM hearts has a higher phosphorylation level than that of the normal hearts. Furthermore, we have examined the distribution of desmin and myofibril organization with immunofluorescent microscopy and immunogold electron microscopy in cultured cardiac myocytes after treatment with the PKC-activating phorbol ester, 12-O-tetradecanylphorbol-13-acetate (TPA). When the cultured normal hamster cardiac cells are treated with TPA, desmin filaments are disassembled and the myofibrils become disarrayed. The myofibril disarray closely mimics that observed in untreated CM cultures. These results suggest that disassembly of desmin filaments, which could be caused by PKC-mediated phosphorylation, may be a factor in myofibril disarray in cardiomyopathic cells and that the intermediate filament protein, desmin, plays an Important role in maintaining myofibril alignment in cardiac cells.

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