Amino Acids, Peptides, and Proteins Commons^™

Methods For The Study Of Signaling Molecules In Membrane Lipid Rafts And Caveolae, Rennolds S. Ostrom, Paul A. Insel

Pharmacy Faculty Articles and Research

Lipid rafts and caveolae are cholesterol- and sphingolipid-rich microdomains of the plasma membrane that concentrate components of certain signal transduction pathways. Interest in and exploration of these microdomains has grown in recent years, especially after the discovery of the biochemical marker of caveolae, caveolin, and the recognition that caveolin interacts with many different signaling molecules via its scaffolding domain. There are three major types of caveolins (1, 2, and 3), with some selectivity in their expression in different tissues. Results assessing lipid raft/caveolae co-localization of molecules in signal transduction pathways have provided support for the idea that signaling components are …

Mouse Cytomegalovirus M33 Is Necessary And Sufficient In Virus-Induced Vascular Smooth Muscle Cell Migration, Ryan Melnychuk, Patsy Smith, Craig N. Kreklywich, Franziska Ruchti, Jennifer Totonchy, Laurel Hall, Lambert Loh, Jay A. Nelson, Susan L. Orloff, Daniel N. Streblow

Pharmacy Faculty Articles and Research

Mouse cytomegalovirus (MCMV) encodes two potential seven-transmembrane-spanning proteins with homologies to cellular chemokine receptors, M33 and M78. While these virus-encoded chemokine receptors are necessary for the in vivo pathogenesis of MCMV, the function of these proteins is unknown. Since vascular smooth muscle cell (SMC) migration is of critical importance for the development of atherosclerosis and other vascular diseases, the ability of M33 to promote SMC motility was assessed. Similar to human CMV, MCMV induced the migration of mouse aortic SMCs but not mouse fibroblasts. To demonstrate whether M33 was required for MCMV-induced SMC migration, we employed interfering-RNA technology to specifically …

The Evolving Role Of Lipid Rafts And Caveolae In G Protein-Coupled Receptor Signaling: Implications For Molecular Pharmacology, Rennolds S. Ostrom, Paul A. Insel

Pharmacy Faculty Articles and Research

The many components of G-protein-coupled receptor (GPCR) signal transduction provide cells with numerous combinations with which to customize their responses to hormones, neurotransmitters, and pharmacologic agonists. GPCRs function as guanine nucleotide exchange factors for heterotrimeric (α, β, γ) G proteins, thereby promoting exchange of GTP for GDP and, in turn, the activation of ‘downstream’ signaling components. Recent data indicate that individual cells express mRNA for perhaps over 100 different GPCRs (out of a total of nearly a thousand GPCR genes), several different combinations of G-protein subunits, multiple regulators of G-protein signaling proteins (which function as GTPase activating proteins), and various …

Nitric Oxide Inhibition Of Adenylyl Cyclase Type 6 Activity Is Dependent Upon Lipid Rafts And Caveolin Signaling Complexes, Rennolds S. Ostrom, Richard A. Bundey, Paul A. Insel

Pharmacy Faculty Articles and Research

Several cell types, including cardiac myocytes and vascular endothelial cells, produce nitric oxide (NO) via both constitutive and inducible isoforms of NO synthase. NO attenuates cardiac contractility and contributes to contractile dysfunction in heart failure, although the precise molecular mechanisms for these effects are poorly defined. Adenylyl cyclase (AC) isoforms type 5 and 6, which are preferentially expressed in cardiac myocytes, may be inhibited via a direct nitrosylation by NO. Because endothelial NO synthase (eNOS and NOS3), β-adrenergic ( AR) receptors, and AC6 all can localize in lipid raft/caveolin-rich microdomains, we sought to understand the role of lipid rafts in …

Human Cytomegalovirus Chemokine Receptor Us28-Induced Smooth Muscle Cell Migration Is Mediated By Focal Adhesion Kinase And Src, Daniel N. Streblow, Jennifer Totonchy, Patsy Smith, Ryan Melnychuk, Laurel Hall, Dora Pancheva, Martine Smit, Paola Casarosa, David D. Schlaepfer, Jay A. Nelson

Pharmacy Faculty Articles and Research

The human cytomegalovirus-encoded chemokine receptor US28 induces arterial smooth muscle cell (SMC) migration; however, the underlying mechanisms involved in this process are unclear. We have previously shown that US28-mediated SMC migration occurs by a ligand-dependent process that is sensitive to proteintyrosine kinase inhibitors. We demonstrate here that US28 signals through the non-receptor protein-tyrosine kinases Src and focal adhesion kinase (FAK) and that this activity is necessary for US28-mediated SMC migration. In the presence of RANTES (regulated on activation normal T cell expressed and secreted), US28 stimulates the production of a FAK Src kinase complex. Interestingly, Src co-immunoprecipitates with US28 in …

Determination Of The Substrate-Docking Site Of Protein Tyrosine Kinase C-Terminal Src Kinase, Sungsoo Lee, Xiaofeng Lin, Nguyen Hai Nam, Keykavous Parang, Gongqin Sun

Pharmacy Faculty Articles and Research

Protein tyrosine kinases (PTK) are key enzymes of mammalian signal transduction. For the fidelity of signal transduction, each PTK phosphorylates only one or a few proteins on specific Tyr residues. Substrate specificity is thought to be mediated by PTK–substrate docking interactions and recognition of the phosphorylation site sequence by the kinase active site. However, a substrate-docking site has not been determined on any PTK. C-terminal Src kinase (Csk) is a PTK that specifically phosphorylates Src family kinases on a C-terminal Tyr. In this study, by sequence alignment and site-specific mutagenesis, we located a substrate-docking site on Csk. Mutations in the …

Hypertonic Stress Co-Stimulates T Cell Il-2 Expression Through A Feedback Mechanism Involving Atp Release And P2 Receptor Activation Of P38 Map Kinase, William H. Loomis, Sachiko Namiki, Rennolds S. Ostrom, Paul A. Insel, Wolfgang G. Junger

Pharmacy Faculty Articles and Research

Hypertonic stress (HS) can alter the function of mammalian cells. We have reported that HS enhances differentiated responses of T cells by increasing their ability to produce interleukin (IL)-2, a finding of clinical interest because hypertonic infusions may modulate immune function in patients. HS shrinks cells and mechanically deforms membranes, which results in ATP release from many cell types. Here we investigate if ATP release is an underlying mechanism through which HS augments T cell function. We found that mechanical stress and HS induced rapid ATP release from Jurkat T cells. HS and exogenous ATP mobilized intracellular Ca2+, activated p38 …

Angiotensin Ii Enhances Adenylyl Cyclase Signaling Via Ca2+/Calmodulin. Gq-Gs Cross-Talk Regulates Collagen Production In Cardiac Fibroblasts, Rennolds S. Ostrom, Jennifer E. Naugle, Miki Hase, Caroline Gregorian, James S. Swaney, Paul A. Insel, Laurence L. Brunton, J. Gary Meszaros

Pharmacy Faculty Articles and Research

Cardiac fibroblasts regulate formation of extracellular matrix in the heart, playing key roles in cardiac remodeling and hypertrophy. In this study, we sought to characterize cross-talk between Gq and Gs signaling pathways and its impact on modulating collagen synthesis by cardiac fibroblasts. Angiotensin II (ANG II) activates cell proliferation and collagen synthesis but also potentiates cyclic AMP (cAMP) production stimulated by β-adrenergic receptors (β-AR). The potentiation of β-AR-stimulated cAMP production by ANG II is reduced by phospholipase C inhibition and enhanced by overexpression of Gq. Ionomycin and thapsigargin increased intracellular Ca2+ levels and potentiated isoproterenol- and forskolin-stimulated cAMP production, whereas …

Receptor Number And Caveolar Co-Localization Determine Receptor Coupling Efficiency To Adenylyl Cyclase, Rennolds S. Ostrom, Caroline Gregorian, Ryan M. Drenan, Yang Xiang, John W. Regan, Paul A. Insel

Pharmacy Faculty Articles and Research

Recent evidence suggests that many signaling molecules localize in microdomains of the plasma membrane, particularly caveolae. In this study, overexpression of adenylyl cyclase was used as a functional probe of G protein-coupled receptor (GPCR) compartmentation. We found that three endogenous receptors in neonatal rat cardiomyocytes couple with different levels of efficiency to the activation of adenylyl cyclase type 6 (AC6), which localizes to caveolin-rich membrane fractions. Overexpression of AC6 enhanced the maximal cAMP response to β1-adrenergic receptor (β1AR)-selective activation 3.7-fold, to β2AR-selective activation only 1.6-fold and to prostaglandin E2 (PGE2) not at all. Therefore, the rank order of efficacy in …

Modulation Of The Pharmacokinetics And Pharmacodynamics Of Proteins By Polyethylene Glycol Conjugation, Reza Mehvar

Pharmacy Faculty Articles and Research

With the rapid advances in the field of biotechnology during the last decade, many peptides and proteins have been produced and evaluated for therapy of various diseases, including cancer. However, rapid clearance and the possibility of immunogenicity after the in vivo administration of these biotechnology-driven products have impeded their marketing. To circumvent these problems, synthetic and natural polymers such as polyethylene glycol (PEG) and dextrans, respectively, have been covalently attached to proteins, and some of these protein-polymer conjugates have shown promising therapeutic results. The conjugation of proteins with polymers usually causes a reduction in the recognition of the protein by …

Cellular Release Of And Response To Atp As Key Determinants Of The Set-Point Of Signal Transduction Pathways, Rennolds S. Ostrom, Caroline Gregorian, Paul A. Insel

Pharmacy Faculty Articles and Research

The determinants of “basal” activity of signaling pathways regulating cellular responses are poorly defined. One possibility is that cells release factors to establish the set-point of such pathways. Here we show that treatment of Madin-Darby canine kidney cells with the nucleotidase apyrase decreases basal arachidonic acid release and cAMP production 30–40% and that inhibitors of P2Y receptor action also affect basal and forskolin-stimulated cAMP accumulation. Changing medium prominently increases extracellular levels of ATP in Madin-Darby canine kidney, COS-7, and HEK-293 cells. Mechanical stimulation of ATP release likely occurs in virtually every experimental protocol with cultured cells, implicating such release and …

Protein Adducts Of Iso[4]Levuglandin E2, A Product Of The Isoprostane Pathway, In Oxidized Low Density Lipoprotein, Robert G. Salomon, Wei Sha, Cynthia Brame, Kamaljit Kaur, Ganesamoorthy Subbanagounder, June O'Neil, Henry F. Hoff, L. Jackson Roberts Ii

Pharmacy Faculty Articles and Research

Levuglandin (LG) E₂, a cytotoxic seco prostanoic acid co-generated with prostaglandins by nonenzymatic rearrangements of the cyclooxygenase-derived endoperoxide, prostaglandin H₂, avidly binds to proteins. That LGE₂-protein adducts can also be generated nonenzymatically is demonstrated by their production during free radical-induced oxidation of low density lipoprotein (LDL). Like oxidized LDL, LGE₂-LDL, but not native LDL, undergoes receptor-mediated uptake and impaired processing by macrophage cells. Since radical-induced lipid oxidation produces isomers of prostaglandins, isoprostanes (isoPs), via endoperoxide intermediates, we postulated previously that a similar family of LG isomers, isoLGs, is cogenerated with isoPs. Now …

Inhibition Of Cpla2-Mediated Arachidonic Acid Release By Cyclic Amp Defines A Negative Feedback Loop For P2y-Receptor Activation In Mdck-D1 Cells, Mingzhao Xing, Steven Post, Rennolds S. Ostrom, Michael Samardzija, Paul A. Insel

Pharmacy Faculty Articles and Research

In Madin-Darby canine kidney D1cells extracellular nucleotides activate P2Y receptors that couple to several signal transduction pathways, including stimulation of multiple phospholipases and adenylyl cyclase. For one class of P2Y receptors, P2Y2 receptors, this stimulation of adenylyl cyclase and increase in cAMP occurs via the conversion of phospholipase A2 (PLA2)-generated arachidonic acid (AA) to prostaglandins (e.g. PGE2). These prostaglandins then stimulate adenylyl cyclase activity, presumably via activation of prostanoid receptors. In the current study we show that agents that increase cellular cAMP levels (including PGE2, forskolin, and the β-adrenergic agonist isoproterenol) can inhibit P2Y receptor-promoted AA release. The protein kinase …

In Vitro Anti-Hepatitis B Virus Activities Of 5’-O-Myristoyl Analogue Derivatives Of 3’-Fluoro-2’,3’-Dideoxythymidine (Flt) And 3’-Azido-2’,3’- Dideoxythymidine (Azt), Keykavous Parang, Leonard I. Wiebe, Edward E. Knaus, Jyy-Shiang Huang, David L. Tyrrell

Pharmacy Faculty Articles and Research

The objective of this study was to evaluate a dual action prodrug concept wherein an unnatural myristic acid analogue is coupled via an ester moiety to the 5’-position of FLT or AZT. Subsequent intracellular cleavage of the prodrug ester would simultaneously release FLT or AZT that could inhibit reverse transcriptase (RT), and the myristic acid analogue that could inhibit myristoyl- CoA:protein N-myristoyltransferase (NMT). Methods: Cytotoxicity (2.2.15 cell culture), and antihepatitis B activity of 5’-O-myristoyl analogue prodrug derivatives of FLT and AZT (2-8) were evaluated in vitro using human liver hepatitis B virus (HBV) producing 2.2.15 cell lines. Results: The 5’- …

Phosphorylation Of The Rex Protein Of Human T-Cell Leukemia Virus Type 1, Yoshifumi Adachi, Terry D. Copeland, Chiaki Takahashi, Tetsuya Nosaka, Aftab Ahmed, Stephen Oroszlan, Masakazu Hatanaka

Pharmacy Faculty Articles and Research

Rex protein, the posttranscriptional regulator of human T-cell leukemia virus type I (HTLV-I), is required for the control of viral structural protein expression and virus replication. Rex is a phosphoprotein found predominantly in the cell nucleolus, whose function is thought to be regulated by its nucleolar localization and phosphorylation. Therefore, we investigated the in vivo phosphorylation of Rex protein in more detail. Phosphorylation of Rex occurred in all HTLV-I-infected cell lines examined in vivo, primarily at serine residues and to a very small extent at threonine residues. Treatment of cells with 12-O-tetradecanoylphorbol-13-acetate (TPA) led to significant but transient enhancement of …

The Amino Acid Sequence Of The Adult Sumatran Tiger (Panthera Tigris, Carnivora) Hemoglobins, Meeno Jahan, Aftab Ahmed, Gerhard Braunitzer, Reinhard Göltenboth

Pharmacy Faculty Articles and Research

The complete amino-acid sequences of the hemoglobins from the adult Sumatran tiger (Panthera tigris sumatrae) have been determined on automatic liquid- and gas-phase sequenators. The globin chains were isolated by reverse phase HPLC on a column of Nucleosil-C4.7V-Acetylserine was detected by FAB-mass spectroscopy as TV-terminal amino acid residue of the βI chain. Comparing the sequences of the globin chains of the tiger with that of human Hb-A, 23 substitutions were recognized in the a, 29 in βI and 28 in the βII chain.

Hemoglobin E B-Thalassemia In A Pakistani Family, Aftab Ahmed, Atiya Abbasi, Gerhard Braunitzer, Zafar H. Zaidi

Pharmacy Faculty Articles and Research

Hemoglobin E is a slow moving B chain variant of hemoglobin, first discovered by Itano¹. Characterized by Hunt et al² showed glutamic acid at B 26 to be replaced by lysine. It is a common variant of hemoglobin in the world and reported in high frequency from South-East Asia^3-6. Cases of Hb E, in combination with thalassemia have been reported on the basis of electrophoretic pattern only. In this communication a case of Hb E with B thalassemia is reported on the basis of amino acid sequencing of the abnormal peptide.

The Primary Structure Of Hemoglobins Of The Adult Jaguar (Panthera Onco, Carnivora), Aftab Ahmed, Meeno Jahan, Zafar H. Zaidi, Gerhard Braunitzer, Reinhard Göltenboth

Pharmacy Faculty Articles and Research

The primary structure of the hemoglobins from Jaguar (Panthera onco) are presented. Electrophoretic separations without and with a dissociating agent revealed the presence of two hemoglobin components, OL2ß\ and a2 02. The separation of the hemoglobin components was achieved by ion-exchange chromatography. The globin chains were separated by ion-exchange chromatography and also by reversed phase HPLC. The amino-acid sequences of the native chains and peptides were determined by liquid-phase and gas-phase sequencing. N-Acetylserine was detected by FAB-mass spectroscopy as N-terminal group of the ßl chain. The sequences are compared with that of human hemoglobin (Hb A).

Abnormal Hemoglobin11 - Hb (Karachi), An A-Chain Abnormality At Position 5 Ala Pro, Aftab Ahmed, Zafar H. Zaidi, S. Ehsanullah

Pharmacy Faculty Articles and Research

Hemoglobin Karachi is a new a chain Variant with amino acid substitution a 5 (A3) Ala-“ Pro. The hematological data on the propositus were normal. In cellulose acetateelectro phoresis this hemoglobin migrated towards the anode slower than HbA.

It is the first a-chain abnormal hemoglobin reported from Pakistani population (JPMA 36:206, 1986).