1
|
López CA, Zhang X, Aydin F, Shrestha R, Van QN, Stanley CB, Carpenter TS, Nguyen K, Patel LA, Chen D, Burns V, Hengartner NW, Reddy TJE, Bhatia H, Di Natale F, Tran TH, Chan AH, Simanshu DK, Nissley DV, Streitz FH, Stephen AG, Turbyville TJ, Lightstone FC, Gnanakaran S, Ingólfsson HI, Neale C. Asynchronous Reciprocal Coupling of Martini 2.2 Coarse-Grained and CHARMM36 All-Atom Simulations in an Automated Multiscale Framework. J Chem Theory Comput 2022; 18:5025-5045. [PMID: 35866871 DOI: 10.1021/acs.jctc.2c00168] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The appeal of multiscale modeling approaches is predicated on the promise of combinatorial synergy. However, this promise can only be realized when distinct scales are combined with reciprocal consistency. Here, we consider multiscale molecular dynamics (MD) simulations that combine the accuracy and macromolecular flexibility accessible to fixed-charge all-atom (AA) representations with the sampling speed accessible to reductive, coarse-grained (CG) representations. AA-to-CG conversions are relatively straightforward because deterministic routines with unique outcomes are achievable. Conversely, CG-to-AA conversions have many solutions due to a surge in the number of degrees of freedom. While automated tools for biomolecular CG-to-AA transformation exist, we find that one popular option, called Backward, is prone to stochastic failure and the AA models that it does generate frequently have compromised protein structure and incorrect stereochemistry. Although these shortcomings can likely be circumvented by human intervention in isolated instances, automated multiscale coupling requires reliable and robust scale conversion. Here, we detail an extension to Multiscale Machine-learned Modeling Infrastructure (MuMMI), including an improved CG-to-AA conversion tool called sinceCG. This tool is reliable (∼98% weakly correlated repeat success rate), automatable (no unrecoverable hangs), and yields AA models that generally preserve protein secondary structure and maintain correct stereochemistry. We describe how the MuMMI framework identifies CG system configurations of interest, converts them to AA representations, and simulates them at the AA scale while on-the-fly analyses provide feedback to update CG parameters. Application to systems containing the peripheral membrane protein RAS and proximal components of RAF kinase on complex eight-component lipid bilayers with ∼1.5 million atoms is discussed in the context of MuMMI.
Collapse
Affiliation(s)
- Cesar A López
- Theoretical Biology and Biophysics, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, United States
| | - Xiaohua Zhang
- Physical and Life Sciences Directorate, Lawrence Livermore National Laboratory, Livermore, California 94550, United States
| | - Fikret Aydin
- Physical and Life Sciences Directorate, Lawrence Livermore National Laboratory, Livermore, California 94550, United States
| | - Rebika Shrestha
- NCI RAS Initiative, Cancer Research Technology Program, Frederick National Laboratory for Cancer Research, Frederick, Maryland 21701, United States
| | - Que N Van
- NCI RAS Initiative, Cancer Research Technology Program, Frederick National Laboratory for Cancer Research, Frederick, Maryland 21701, United States
| | - Christopher B Stanley
- Computational Sciences and Engineering Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37830, United States
| | - Timothy S Carpenter
- Physical and Life Sciences Directorate, Lawrence Livermore National Laboratory, Livermore, California 94550, United States
| | - Kien Nguyen
- Theoretical Biology and Biophysics, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, United States
| | - Lara A Patel
- Theoretical Biology and Biophysics, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, United States.,Center for Nonlinear Studies, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, United States
| | - De Chen
- NCI RAS Initiative, Cancer Research Technology Program, Frederick National Laboratory for Cancer Research, Frederick, Maryland 21701, United States
| | - Violetta Burns
- Theoretical Biology and Biophysics, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, United States
| | - Nicolas W Hengartner
- Theoretical Biology and Biophysics, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, United States
| | - Tyler J E Reddy
- Theoretical Biology and Biophysics, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, United States
| | - Harsh Bhatia
- Computing Directorate, Lawrence Livermore National Laboratory, Livermore, California 94550, United States
| | - Francesco Di Natale
- Computing Directorate, Lawrence Livermore National Laboratory, Livermore, California 94550, United States
| | - Timothy H Tran
- NCI RAS Initiative, Cancer Research Technology Program, Frederick National Laboratory for Cancer Research, Frederick, Maryland 21701, United States
| | - Albert H Chan
- NCI RAS Initiative, Cancer Research Technology Program, Frederick National Laboratory for Cancer Research, Frederick, Maryland 21701, United States
| | - Dhirendra K Simanshu
- NCI RAS Initiative, Cancer Research Technology Program, Frederick National Laboratory for Cancer Research, Frederick, Maryland 21701, United States
| | - Dwight V Nissley
- NCI RAS Initiative, Cancer Research Technology Program, Frederick National Laboratory for Cancer Research, Frederick, Maryland 21701, United States
| | - Frederick H Streitz
- Physical and Life Sciences Directorate, Lawrence Livermore National Laboratory, Livermore, California 94550, United States
| | - Andrew G Stephen
- NCI RAS Initiative, Cancer Research Technology Program, Frederick National Laboratory for Cancer Research, Frederick, Maryland 21701, United States
| | - Thomas J Turbyville
- NCI RAS Initiative, Cancer Research Technology Program, Frederick National Laboratory for Cancer Research, Frederick, Maryland 21701, United States
| | - Felice C Lightstone
- Physical and Life Sciences Directorate, Lawrence Livermore National Laboratory, Livermore, California 94550, United States
| | - Sandrasegaram Gnanakaran
- Theoretical Biology and Biophysics, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, United States
| | - Helgi I Ingólfsson
- Physical and Life Sciences Directorate, Lawrence Livermore National Laboratory, Livermore, California 94550, United States
| | - Chris Neale
- Theoretical Biology and Biophysics, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, United States
| |
Collapse
|
2
|
Abstract
Cholesterol is a key steroidal, lipid biomolecule found abundantly in plasma membranes of eukaryotic cells. It is an important structural component of cellular membranes and regulates membrane fluidity and permeability. Cholesterol is also essential for normal functioning of key proteins including ion-channels, G protein-coupled receptors (GPCRs), membrane bound steroid receptors, and receptor kinases. It is thought that cholesterol exerts its actions via specific binding to chiral proteins and lipids as well as through non-specific physiochemical interactions. Distinguishing between the specific and the non-specific interactions can be difficult. Although much remains unclear, progress has been made in recent years by utilizing ent-cholesterol, the enantiomer of natural cholesterol (nat-cholesterol) as a probe. Ent-Cholesterol is the non-superimposable mirror image of nat-cholesterol and exhibits identical physiochemical properties as nat-cholesterol. Hence, if the biological effects of cholesterol result solely due to membrane effects, it is expected that there will be no difference between ent-cholesterol and nat-cholesterol. However, when direct binding with chiral proteins and lipids is involved, the enantiomer is expected to potentially elicit significantly different, measurable effects due to formation of diastereomeric complexes. In this chapter, we have reviewed the literature related to ent-cholesterol and its use as a probe for various biophysical and biological interactions of cholesterol.
Collapse
|
3
|
Surface interactions determined by stereostructure on the example of 7-hydroxycholesterol epimers – The Langmuir monolayer study. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2019; 1861:1275-1283. [DOI: 10.1016/j.bbamem.2019.05.005] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/23/2018] [Revised: 12/20/2018] [Accepted: 01/06/2019] [Indexed: 01/06/2023]
|
4
|
Bukiya AN, Dopico AM. Regulation of BK Channel Activity by Cholesterol and Its Derivatives. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2019; 1115:53-75. [DOI: 10.1007/978-3-030-04278-3_3] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
|
5
|
Sakai N, Matile S. Conjugated Polyimine Dynamers as Phase-Sensitive Membrane Probes. J Am Chem Soc 2018; 140:11438-11443. [PMID: 30156837 DOI: 10.1021/jacs.8b06668] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
In this report, dynamic polyimines are introduced as multifunctional sensors of lipid bilayer phases. Under mildly acidic conditions, self-condensation of push-pull amino formyl fluorenes into polyimines occurs in solid- or liquid-ordered phases but not in liquid-disordered phases of vesicular membranes. The obtained conjugated polymers are characterized by a progressive red shift of the absorption maxima, the appearance of exciton-coupled circular dichroism (CD) bands, and fluorescence quenching. These characteristics allow multiple modes of detection of membrane phases, which are known to change under membrane tension.
Collapse
Affiliation(s)
- Naomi Sakai
- Department of Organic Chemistry , University of Geneva , CH-1211 Geneva 4, Switzerland
| | - Stefan Matile
- Department of Organic Chemistry , University of Geneva , CH-1211 Geneva 4, Switzerland
| |
Collapse
|
6
|
Dopico AM, Bukiya AN. Regulation of Ca 2+-Sensitive K + Channels by Cholesterol and Bile Acids via Distinct Channel Subunits and Sites. CURRENT TOPICS IN MEMBRANES 2017; 80:53-93. [PMID: 28863822 DOI: 10.1016/bs.ctm.2017.07.001] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Cholesterol (CLR) conversion into bile acids (BAs) in the liver constitutes the major pathway for CLR elimination from the body. Moreover, these steroids regulate each other's metabolism. While the roles of CLR and BAs in regulating metabolism and tissue function are well known, research of the last two decades revealed the existence of specific protein receptors for CLR or BAs in tissues with minor contribution to lipid metabolism, raising the possibility that these lipids serve as signaling molecules throughout the body. Among other lipids, CLR and BAs regulate ionic current mediated by the activity of voltage- and Ca2+-gated, K+ channels of large conductance (BK channels) and, thus, modulate cell physiology and participate in tissue pathophysiology. Initial work attributed modification of BK channel function by CLR or BAs to the capability of these steroids to directly interact with bilayer lipids and thus alter the physicochemical properties of the bilayer with eventual modification of BK channel function. Based on our own work and that of others, we now review evidence that supports direct interactions between CLR or BA and specific BK protein subunits, and the consequence of such interactions on channel activity and organ function, with a particular emphasis on arterial smooth muscle. For each steroid type, we will also briefly discuss several mechanisms that may underlie modification of channel steady-state activity. Finally, we will present novel computational data that provide a chemical basis for differential recognition of CLR vs lithocholic acid by distinct BK channel subunits and recognition sites.
Collapse
Affiliation(s)
- Alex M Dopico
- College of Medicine, The University of Tennessee Health Science Center, Memphis, TN, United States.
| | - Anna N Bukiya
- College of Medicine, The University of Tennessee Health Science Center, Memphis, TN, United States
| |
Collapse
|
7
|
Zhang F, Sun Y, Tian D, Li H. Chiral Selective Transport of Proteins by Cysteine-Enantiomer-Modified Nanopores. Angew Chem Int Ed Engl 2017. [DOI: 10.1002/ange.201701255] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- Fan Zhang
- Key Laboratory of Pesticide and Chemical Biology (CCNU), Ministry of Education, College of Chemistry; Central China Normal University; Wuhan 430079 P.R. China
| | - Yue Sun
- Key Laboratory of Pesticide and Chemical Biology (CCNU), Ministry of Education, College of Chemistry; Central China Normal University; Wuhan 430079 P.R. China
| | - Demei Tian
- Key Laboratory of Pesticide and Chemical Biology (CCNU), Ministry of Education, College of Chemistry; Central China Normal University; Wuhan 430079 P.R. China
| | - Haibing Li
- Key Laboratory of Pesticide and Chemical Biology (CCNU), Ministry of Education, College of Chemistry; Central China Normal University; Wuhan 430079 P.R. China
| |
Collapse
|
8
|
Zhang F, Sun Y, Tian D, Li H. Chiral Selective Transport of Proteins by Cysteine-Enantiomer-Modified Nanopores. Angew Chem Int Ed Engl 2017; 56:7186-7190. [DOI: 10.1002/anie.201701255] [Citation(s) in RCA: 53] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2017] [Revised: 04/07/2017] [Indexed: 11/12/2022]
Affiliation(s)
- Fan Zhang
- Key Laboratory of Pesticide and Chemical Biology (CCNU), Ministry of Education, College of Chemistry; Central China Normal University; Wuhan 430079 P.R. China
| | - Yue Sun
- Key Laboratory of Pesticide and Chemical Biology (CCNU), Ministry of Education, College of Chemistry; Central China Normal University; Wuhan 430079 P.R. China
| | - Demei Tian
- Key Laboratory of Pesticide and Chemical Biology (CCNU), Ministry of Education, College of Chemistry; Central China Normal University; Wuhan 430079 P.R. China
| | - Haibing Li
- Key Laboratory of Pesticide and Chemical Biology (CCNU), Ministry of Education, College of Chemistry; Central China Normal University; Wuhan 430079 P.R. China
| |
Collapse
|
9
|
Suga K, Tauchi A, Ishigami T, Okamoto Y, Umakoshi H. Preferential Adsorption of l-Histidine onto DOPC/Sphingomyelin/3β-[N-(N',N'-dimethylaminoethane)carbamoyl]cholesterol Liposomes in the Presence of Chiral Organic Acids. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2017; 33:3831-3838. [PMID: 28272888 DOI: 10.1021/acs.langmuir.6b03264] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
We investigated the effect of organic acids such as mandelic acid (MA) and tartaric acid (TA) on the adsorption behavior of both histidine (His) and propranolol (PPL) onto liposomes. A cationic and heterogeneous liposome prepared using 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC)/sphingomyelin (SM)/3β-[N-(N',N'-dimethylaminoethane)carbamoyl]cholesterol (DC-Ch) in a ratio of (4/3/3) showed the highest adsorption efficiency of MA and TA independent of chirality, while neutral liposome DOPC/SM/cholesterol = (4/3/3) showed low efficiency. As expected, electrostatic interactions were dominant in MA or TA adsorption onto DOPC/SM/DC-Ch = (4/3/3) liposomes, suggesting that organic acids had adsorbed onto SM/DC-Ch-enriched domains. The adsorption behaviors of organic acids onto DOPC/SM/DC-Ch = (4/3/3) were governed by Langmuir adsorption isotherms. For adsorption, the membrane polarities slightly decreased (i.e., membrane surface was hydrophilic), but no alterations in membrane fluidity were observed. In the presence of organic acids that had been preincubated with DOPC/SM/DC-Ch = (4/3/3), the adsorption of l- and d-His onto those liposomes was examined. Preferential l-His adsorption was dramatically prevented only in the presence of l-MA, suggesting that the adsorption sites for l-His and l-MA on DOPC/SM/DC-Ch = (4/3/3) liposomes are competitive, while those for l-His and d-MA, l-TA, and d-TA are isolated.
Collapse
Affiliation(s)
- Keishi Suga
- Division of Chemical Engineering, Graduate School of Engineering Science, Osaka University , 1-3 Machikaneyamacho, Toyonaka, Osaka 560-8531, Japan
| | - Atsushi Tauchi
- Division of Chemical Engineering, Graduate School of Engineering Science, Osaka University , 1-3 Machikaneyamacho, Toyonaka, Osaka 560-8531, Japan
| | - Takaaki Ishigami
- Division of Chemical Engineering, Graduate School of Engineering Science, Osaka University , 1-3 Machikaneyamacho, Toyonaka, Osaka 560-8531, Japan
| | - Yukihiro Okamoto
- Division of Chemical Engineering, Graduate School of Engineering Science, Osaka University , 1-3 Machikaneyamacho, Toyonaka, Osaka 560-8531, Japan
| | - Hiroshi Umakoshi
- Division of Chemical Engineering, Graduate School of Engineering Science, Osaka University , 1-3 Machikaneyamacho, Toyonaka, Osaka 560-8531, Japan
| |
Collapse
|
10
|
Zhang B, Naik JS, Jernigan NL, Walker BR, Resta TC. Reduced membrane cholesterol limits pulmonary endothelial Ca 2+ entry after chronic hypoxia. Am J Physiol Heart Circ Physiol 2017; 312:H1176-H1184. [PMID: 28364016 DOI: 10.1152/ajpheart.00097.2017] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/13/2017] [Revised: 03/17/2017] [Accepted: 03/24/2017] [Indexed: 12/22/2022]
Abstract
Chronic hypoxia (CH)-induced pulmonary hypertension is associated with diminished production of endothelium-derived Ca2+-dependent vasodilators such as nitric oxide. Interestingly, ATP-induced endothelial Ca2+ entry as well as membrane cholesterol (Chol) are decreased in pulmonary arteries from CH rats (4 wk, barometric pressure = 380 Torr) compared with normoxic controls. Store-operated Ca2+ entry (SOCE) and depolarization-induced Ca2+ entry are major components of the response to ATP and are similarly decreased after CH. We hypothesized that membrane Chol facilitates both SOCE and depolarization-induced pulmonary endothelial Ca2+ entry and that CH attenuates these responses by decreasing membrane Chol. To test these hypotheses, we administered Chol or epicholesterol (Epichol) to acutely isolated pulmonary arterial endothelial cells (PAECs) from control and CH rats to either supplement or replace native Chol, respectively. The efficacy of membrane Chol manipulation was confirmed by filipin staining. Epichol greatly reduced ATP-induced Ca2+ influx in PAECs from control rats. Whereas Epichol similarly blunted endothelial SOCE in PAECs from both groups, Chol supplementation restored diminished SOCE in PAECs from CH rats while having no effect in controls. Similar effects of Chol manipulation on PAEC Ca2+ influx were observed in response to a depolarizing stimulus of KCl. Furthermore, KCl-induced Ca2+ entry was inhibited by the T-type Ca2+ channel antagonist mibefradil but not the L-type Ca2+ channel inhibitor diltiazem. We conclude that PAEC membrane Chol is required for ATP-induced Ca2+ entry and its two components, SOCE and depolarization-induced Ca2+ entry, and that reduced Ca2+ entry after CH may be due to loss of this key regulator.NEW & NOTEWORTHY This research is the first to examine the direct role of membrane cholesterol in regulating pulmonary endothelial agonist-induced Ca2+ entry and its components. The results provide a potential mechanism by which chronic hypoxia impairs pulmonary endothelial Ca2+ influx, which may contribute to pulmonary hypertension.
Collapse
Affiliation(s)
- Bojun Zhang
- Vascular Physiology Group, Department of Cell Biology and Physiology, University of New Mexico Health Sciences Center, Albuquerque, New Mexico
| | - Jay S Naik
- Vascular Physiology Group, Department of Cell Biology and Physiology, University of New Mexico Health Sciences Center, Albuquerque, New Mexico
| | - Nikki L Jernigan
- Vascular Physiology Group, Department of Cell Biology and Physiology, University of New Mexico Health Sciences Center, Albuquerque, New Mexico
| | - Benjimen R Walker
- Vascular Physiology Group, Department of Cell Biology and Physiology, University of New Mexico Health Sciences Center, Albuquerque, New Mexico
| | - Thomas C Resta
- Vascular Physiology Group, Department of Cell Biology and Physiology, University of New Mexico Health Sciences Center, Albuquerque, New Mexico
| |
Collapse
|
11
|
Kato R, Nakahara H, Shibata O. Interfacial Properties of Binary Systems Composed of DPPC and Perfluorinated Double Long-Chain Salts with Divalent Counterions of Separate Electric Charge. J Oleo Sci 2017; 66:479-489. [DOI: 10.5650/jos.ess16208] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Affiliation(s)
- Riku Kato
- Department of Biophysical Chemistry, Graduate School & Faculty of Pharmaceutical Sciences, Nagasaki International University
| | - Hiromichi Nakahara
- Department of Biophysical Chemistry, Graduate School & Faculty of Pharmaceutical Sciences, Nagasaki International University
| | - Osamu Shibata
- Department of Biophysical Chemistry, Graduate School & Faculty of Pharmaceutical Sciences, Nagasaki International University
| |
Collapse
|
12
|
Bisen S, Seleverstov O, Belani J, Rychnovsky S, Dopico AM, Bukiya AN. Distinct mechanisms underlying cholesterol protection against alcohol-induced BK channel inhibition and resulting vasoconstriction. BIOCHIMICA ET BIOPHYSICA ACTA 2016; 1861:1756-1766. [PMID: 27565113 PMCID: PMC5274633 DOI: 10.1016/j.bbalip.2016.08.013] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/04/2016] [Revised: 07/21/2016] [Accepted: 08/22/2016] [Indexed: 02/01/2023]
Abstract
Alcohol (ethanol) at concentrations reached in blood following moderate to heavy drinking (30-80mM) reduces cerebral artery diameter via inhibition of voltage- and calcium-gated potassium channels of large conductance (BK) in cerebral artery smooth muscle. These channels consist of channel-forming α and regulatory β1 subunits. A high-cholesterol diet protects against ethanol-induced constriction via accumulation of cholesterol within the vasculature. The molecular mechanisms of this protection remain unknown. In the present work, we demonstrate that in vitro cholesterol enrichment of rat middle cerebral arteries significantly increased cholesterol within arterial tissues and blunted constriction by 50mM of ethanol. Ethanol-induced BK channel inhibition in inside-out patches excised from freshly isolated cerebral artery myocytes was also abolished by cholesterol enrichment. Enrichment of arteries with enantiomeric cholesterol (ent-cholesterol) also blunted BK channel inhibition and cerebral artery constriction in response to ethanol. The similar protection of cholesterol and ent-cholesterol against ethanol action indicates that this protection does not require protein site(s) that specifically sense natural cholesterol. Cholesterol-driven protection against ethanol-induced BK channel inhibition and vasoconstriction was replicated in myocytes and middle cerebral arteries of C57BL/6 mice. BK β1 subunits are known to regulate vascular diameter and its modification by ethanol. However, blunting of an ethanol effect by in vitro cholesterol enrichment was observed in arteries and myocyte membrane patches from BK β1 (KCNMB1) knockout mice. Thus, BK β1 subunits are not needed for cholesterol protection against ethanol effect on BK channel function and cerebral artery diameter.
Collapse
Affiliation(s)
- Shivantika Bisen
- Department of Pharmacology, The University of Tennessee Health Science Center, Memphis, TN 38163, USA
| | - Olga Seleverstov
- Department of Pharmacology, The University of Tennessee Health Science Center, Memphis, TN 38163, USA
| | - Jitendra Belani
- Department of Chemistry, School of Physical Sciences, University of California, Irvine, 3038B FRH, Mail Code: 2025, Irvine, CA 92697, USA
| | - Scott Rychnovsky
- Department of Chemistry, School of Physical Sciences, University of California, Irvine, 3038B FRH, Mail Code: 2025, Irvine, CA 92697, USA
| | - Alex M Dopico
- Department of Pharmacology, The University of Tennessee Health Science Center, Memphis, TN 38163, USA
| | - Anna N Bukiya
- Department of Pharmacology, The University of Tennessee Health Science Center, Memphis, TN 38163, USA.
| |
Collapse
|
13
|
Fürst O, Nichols CG, Lamoureux G, D'Avanzo N. Identification of a cholesterol-binding pocket in inward rectifier K(+) (Kir) channels. Biophys J 2016; 107:2786-2796. [PMID: 25517146 DOI: 10.1016/j.bpj.2014.10.066] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2014] [Revised: 09/24/2014] [Accepted: 10/08/2014] [Indexed: 11/28/2022] Open
Abstract
Cholesterol is the major sterol component of all mammalian plasma membranes. Recent studies have shown that cholesterol inhibits both bacterial (KirBac1.1 and KirBac3.1) and eukaryotic (Kir2.1) inward rectifier K(+) (Kir) channels. Lipid-sterol interactions are not enantioselective, and the enantiomer of cholesterol (ent-cholesterol) does not inhibit Kir channel activity, suggesting that inhibition results from direct enantiospecific binding to the channel, and not indirect effects of changes to the bilayer. Furthermore, conservation of the effect of cholesterol among prokaryotic and eukaryotic Kir channels suggests an evolutionary conserved cholesterol-binding pocket, which we aimed to identify. Computational experiments were performed by docking cholesterol to the atomic structures of Kir2.2 (PDB: 3SPI) and KirBac1.1 (PDB: 2WLL) using Autodock 4.2. Poses were assessed to ensure biologically relevant orientation and then clustered according to location and orientation. The stability of cholesterol in each of these poses was then confirmed by molecular dynamics simulations. Finally, mutation of key residues (S95H and I171L) in this putative binding pocket found within the transmembrane domain of Kir2.1 channels were shown to lead to a loss of inhibition by cholesterol. Together, these data provide support for this location as a biologically relevant pocket.
Collapse
Affiliation(s)
- Oliver Fürst
- Département de Physiologie Moléculaire et Intégrative and Groupe d'Étude des Protéines Membranaires (GÉPROM), Université de Montréal, Montreal, Quebec, Canada
| | - Colin G Nichols
- Department of Cell Biology and Physiology and Center for Investigation of Membrane Excitabiltiy Diseases, Washington University School of Medicine, St. Louis, Missouri
| | - Guillaume Lamoureux
- Department of Chemistry and Biochemistry, Centre for Research in Molecular Modeling (CERMM), Groupe d'Étude des Protéines Membranaires (GÉPROM), Concordia University, Montreal, Quebec, Canada
| | - Nazzareno D'Avanzo
- Département de Physiologie Moléculaire et Intégrative and Groupe d'Étude des Protéines Membranaires (GÉPROM), Université de Montréal, Montreal, Quebec, Canada.
| |
Collapse
|
14
|
Caminati G, Cicchi S, Lascialfari L, Brandi A. Separation of Enantiomers of a Phospholipid in Langmuir Monolayers by a New Selector. Chirality 2015; 27:784-7. [DOI: 10.1002/chir.22508] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2015] [Revised: 07/31/2015] [Accepted: 08/03/2015] [Indexed: 11/10/2022]
Affiliation(s)
- Gabriella Caminati
- Department of Chemistry “Ugo Schiff,”; Università degli Studi di Firenze; Firenze Italy
| | - Stefano Cicchi
- Department of Chemistry “Ugo Schiff,”; Università degli Studi di Firenze; Firenze Italy
| | - Luisa Lascialfari
- Department of Chemistry “Ugo Schiff,”; Università degli Studi di Firenze; Firenze Italy
- Chemistry, Material and Chemical Engineering Department "Giulio Natta,"; Politecnico di Milano; Via L. Mancinelli 7 20131 Milano Italy
| | - Alberto Brandi
- Department of Chemistry “Ugo Schiff,”; Università degli Studi di Firenze; Firenze Italy
| |
Collapse
|
15
|
Salvador JAR, Carvalho JFS, Neves MAC, Silvestre SM, Leitão AJ, Silva MMC, Sá e Melo ML. Anticancer steroids: linking natural and semi-synthetic compounds. Nat Prod Rep 2013; 30:324-74. [PMID: 23151898 DOI: 10.1039/c2np20082a] [Citation(s) in RCA: 197] [Impact Index Per Article: 17.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Steroids, a widespread class of natural organic compounds occurring in animals, plants and fungi, have shown great therapeutic value for a broad array of pathologies. The present overview is focused on the anticancer activity of steroids, which is very representative of a rich structural molecular diversity and ability to interact with various biological targets and pathways. This review encompasses the most relevant discoveries on steroid anticancer drugs and leads through the last decade and comprises 668 references.
Collapse
Affiliation(s)
- Jorge A R Salvador
- Laboratory of Pharmaceutical Chemistry, Faculty of Pharmacy, University of Coimbra, Polo das Ciências da Saúde, 3000-508, Coimbra, Portugal.
| | | | | | | | | | | | | |
Collapse
|
16
|
Scholtysek P, Li Z, Kressler J, Blume A. Interactions of DPPC with semitelechelic poly(glycerol methacrylate)s with perfluoroalkyl end groups. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2012; 28:15651-62. [PMID: 23046205 DOI: 10.1021/la3028226] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Semitelechelic poly(glycerol methacrylate)s having a perfluoroalkyl end group (PGMA(n)-F(9)) were synthesized by ATRP. The interactions of these polymers with different degrees of polymerization with chiral or racemic dipalmitoylphosphatidylcholine (l-DPPC, d-DPPC, or rac-DPPC) monolayers at the air/water interface were studied. Langmuir trough measurements coupled with epifluorescence microscopy allowed for the observation of domain formation within the coexistence region of liquid-expanded (LE) and liquid-condensed (LC) states of DPPC in mixed DPPC-polymer films prepared by spreading a solution of both compounds in the same organic solvent (cospread films). Because of the incorporation of PGMA(n)-F(9) polymers into the LE phase and their line-active behavior, a formation of novel types of domains could be observed. During compression, a thinning out of the tips of two- to six-lobed flowerlike domain structures and consecutive spiral formation appeared for l- and d-DPPC within the two-phase coexistence region (LE/LC) of the monolayer. When rac-DPPC was used, symmetrical stripe formation was induced at the vertices of the domains and fingerprint-like structures were created by convection-inducing movements of the domains at the air/water interface. Additional investigations of the interaction of PGMA(n)-F(9) with DPPC vesicles using differential scanning calorimetry (DSC) supported the finding on the monolayer system that the incorporation of the polymers into the lipid monolayers is not solely driven by the perfluoroalkyl chain but significantly by the hydrophilic polymer part. Apparently, interactions of the PGMA chain with the lipid headgroups are important as the interactions increase with the elongation of the polymer chain, indicating that the polymer also has hydrophobic character.
Collapse
Affiliation(s)
- Peggy Scholtysek
- Institute of Chemistry, Martin-Luther University Halle-Wittenberg, Saale, Germany
| | | | | | | |
Collapse
|
17
|
Albada HB, Chiriac AI, Wenzel M, Penkova M, Bandow JE, Sahl HG, Metzler-Nolte N. Modulating the activity of short arginine-tryptophan containing antibacterial peptides with N-terminal metallocenoyl groups. Beilstein J Org Chem 2012; 8:1753-64. [PMID: 23209509 PMCID: PMC3511009 DOI: 10.3762/bjoc.8.200] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2012] [Accepted: 09/06/2012] [Indexed: 11/23/2022] Open
Abstract
A series of small synthetic arginine and tryptophan containing peptides was prepared and analyzed for their antibacterial activity. The effect of N-terminal substitution with metallocenoyl groups such as ferrocene (FcCO) and ruthenocene (RcCO) was investigated. Antibacterial activity in different media, growth inhibition, and killing kinetics of the most active peptides were determined. The toxicity of selected derivatives was determined against erythrocytes and three human cancer cell lines. It was shown that the replacement of an N-terminal arginine residue with a metallocenoyl moiety modulates the activity of WRWRW-peptides against Gram-positive and Gram-negative bacteria. MIC values of 2–6 µM for RcCO-W(RW)2 and 1–11 µM for (RW)3 were determined. Interestingly, W(RW)2-peptides derivatized with ferrocene were significantly less active than those derivatized with ruthenocene which have similar structural but different electronic properties, suggesting a major influence of the latter. The high activities observed for the RcCO-W(RW)2- and (RW)3-peptides led to an investigation of the origin of activity of these peptides using several important activity-related parameters. Firstly, killing kinetics of the RcCO-W(RW)2-peptide versus killing kinetics of the (RW)3 derivative showed faster reduction of the colony forming units for the RcCO-W(RW)2-peptide, although MIC values indicated higher activity for the (RW)3-peptide. This was confirmed by growth inhibition studies. Secondly, hemolysis studies revealed that both peptides did not lead to significant destruction of erythrocytes, even up to 500 µg/mL for (RW)3 and 250 µg/mL for RcCO-W(RW)2. In addition, toxicity against three human cancer cell lines (HepG2, HT29, MCF7) showed that the (RW)3-peptide had an IC50 value of ~140 µM and the RcW(RW)2 one of ~90 µM, indicating a potentially interesting therapeutic window. Both the killing kinetics and growth inhibition studies presented in this work point to a membrane-based mode of action for these two peptides, each having different kinetic parameters.
Collapse
Affiliation(s)
- H Bauke Albada
- Inorganic Chemistry I - Bioinorganic Chemistry, Faculty of Chemistry and Biochemistry, Ruhr University Bochum, Universitätsstraße 150, 44801 Bochum, Germany
| | | | | | | | | | | | | |
Collapse
|
18
|
Large conductance, calcium- and voltage-gated potassium (BK) channels: regulation by cholesterol. Pharmacol Ther 2012; 135:133-50. [PMID: 22584144 DOI: 10.1016/j.pharmthera.2012.05.002] [Citation(s) in RCA: 64] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2012] [Accepted: 04/09/2012] [Indexed: 11/21/2022]
Abstract
Cholesterol (CLR) is an essential component of eukaryotic plasma membranes. CLR regulates the membrane physical state, microdomain formation and the activity of membrane-spanning proteins, including ion channels. Large conductance, voltage- and Ca²⁺-gated K⁺ (BK) channels link membrane potential to cell Ca²⁺ homeostasis. Thus, they control many physiological processes and participate in pathophysiological mechanisms leading to human disease. Because plasmalemma BK channels cluster in CLR-rich membrane microdomains, a major driving force for studying BK channel-CLR interactions is determining how membrane CLR controls the BK current phenotype, including its pharmacology, channel sorting, distribution, and role in cell physiology. Since both BK channels and CLR tissue levels play a pathophysiological role in human disease, identifying functional and structural aspects of the CLR-BK channel interaction may open new avenues for therapeutic intervention. Here, we review the studies documenting membrane CLR-BK channel interactions, dissecting out the many factors that determine the final BK current response to changes in membrane CLR content. We also summarize work in reductionist systems where recombinant BK protein is studied in artificial lipid bilayers, which documents a direct inhibition of BK channel activity by CLR and builds a strong case for a direct interaction between CLR and the BK channel-forming protein. Bilayer lipid-mediated mechanisms in CLR action are also discussed. Finally, we review studies of BK channel function during hypercholesterolemia, and underscore the many consequences that the CLR-BK channel interaction brings to cell physiology and human disease.
Collapse
|
19
|
Sorrenti A, Altieri B, Ceccacci F, Di Profio P, Germani R, Giansanti L, Savelli G, Mancini G. Deracemization of bilirubin as the marker of the chirality of micellar aggregates. Chirality 2011; 24:78-85. [DOI: 10.1002/chir.21026] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2011] [Accepted: 08/11/2011] [Indexed: 11/10/2022]
|
20
|
D'Avanzo N, Hyrc K, Enkvetchakul D, Covey DF, Nichols CG. Enantioselective protein-sterol interactions mediate regulation of both prokaryotic and eukaryotic inward rectifier K+ channels by cholesterol. PLoS One 2011; 6:e19393. [PMID: 21559361 PMCID: PMC3084843 DOI: 10.1371/journal.pone.0019393] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2011] [Accepted: 03/29/2011] [Indexed: 02/06/2023] Open
Abstract
Cholesterol is the major sterol component of all mammalian cell plasma membranes and plays a critical role in cell function and growth. Previous studies have shown that cholesterol inhibits inward rectifier K+ (Kir) channels, but have not distinguished whether this is due directly to protein-sterol interactions or indirectly to changes in the physical properties of the lipid bilayer. Using purified bacterial and eukaryotic Kir channels reconstituted into liposomes of controlled lipid composition, we demonstrate by 86Rb+ influx assays that bacterial Kir channels (KirBac1.1 and KirBac3.1) and human Kir2.1 are all inhibited by cholesterol, most likely by locking the channels into prolonged closed states, whereas the enantiomer, ent-cholesterol, does not inhibit these channels. These data indicate that cholesterol regulates Kir channels through direct protein-sterol interactions likely taking advantage of an evolutionarily conserved binding pocket.
Collapse
Affiliation(s)
- Nazzareno D'Avanzo
- Department of Cell Biology and Physiology, and Center for Investigation of Membrane Excitability Diseases, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - Krzysztof Hyrc
- Department of Cell Biology and Physiology, and Center for Investigation of Membrane Excitability Diseases, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - Decha Enkvetchakul
- Department of Pharmacological and Physiological Science, Saint Louis University School of Medicine, St. Louis, Missouri, United States of America
| | - Douglas F. Covey
- Department of Developmental Biology, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - Colin G. Nichols
- Department of Cell Biology and Physiology, and Center for Investigation of Membrane Excitability Diseases, Washington University School of Medicine, St. Louis, Missouri, United States of America
- * E-mail:
| |
Collapse
|
21
|
Bukiya AN, Belani JD, Rychnovsky S, Dopico AM. Specificity of cholesterol and analogs to modulate BK channels points to direct sterol-channel protein interactions. J Gen Physiol 2011; 137:93-110. [PMID: 21149543 PMCID: PMC3010061 DOI: 10.1085/jgp.201010519] [Citation(s) in RCA: 70] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2010] [Accepted: 11/22/2010] [Indexed: 11/26/2022] Open
Abstract
The activity (Po) of large-conductance voltage/Ca(2+)-gated K(+) (BK) channels is blunted by cholesterol levels within the range found in natural membranes. We probed BK channel-forming α (cbv1) subunits in phospholipid bilayers with cholesterol and related monohydroxysterols and performed computational dynamics to pinpoint the structural requirements for monohydroxysterols to reduce BK Po and obtain insights into cholesterol's mechanism of action. Cholesterol, cholestanol, and coprostanol reduced Po by shortening mean open and lengthening mean closed times, whereas epicholesterol, epicholestanol, epicoprostanol, and cholesterol trisnorcholenic acid were ineffective. Thus, channel inhibition by monohydroxysterols requires the β configuration of the C3 hydroxyl and is favored by the hydrophobic nature of the side chain, while having lax requirements on the sterol A/B ring fusion. Destabilization of BK channel open state(s) has been previously interpreted as reflecting increased bilayer lateral stress by cholesterol. Lateral stress is controlled by the sterol molecular area and lipid monolayer lateral tension, the latter being related to the sterol ability to adopt a planar conformation in lipid media. However, we found that the differential efficacies of monohydroxysterols to reduce Po (cholesterol≥coprostanol≥cholestanol>>>epicholesterol) did not follow molecular area rank (coprostanol>>epicholesterol>cholesterol>cholestanol). In addition, computationally predicted energies for cholesterol (effective BK inhibitor) and epicholesterol (ineffective) to adopt a planar conformation were similar. Finally, cholesterol and coprostanol reduced Po, yet these sterols have opposite effects on tight lipid packing and, likely, on lateral stress. Collectively, these findings suggest that an increase in bilayer lateral stress is unlikely to underlie the differential ability of cholesterol and related steroids to inhibit BK channels. Remarkably, ent-cholesterol (cholesterol mirror image) failed to reduce Po, indicating that cholesterol efficacy requires sterol stereospecific recognition by a protein surface. The BK channel phenotype resembled that of α homotetramers. Thus, we hypothesize that a cholesterol-recognizing protein surface resides at the BK α subunit itself.
Collapse
Affiliation(s)
- Anna N. Bukiya
- Department of Pharmacology, College of Medicine, The University of Tennessee Health Science Center, Memphis, TN 38163
| | | | - Scott Rychnovsky
- Department of Chemistry, University of California, Irvine, CA 92697
| | - Alex M. Dopico
- Department of Pharmacology, College of Medicine, The University of Tennessee Health Science Center, Memphis, TN 38163
| |
Collapse
|
22
|
Manna M, Mukhopadhyay C. Cholesterol driven alteration of the conformation and dynamics of phospholamban in model membranes. Phys Chem Chem Phys 2011; 13:20188-98. [DOI: 10.1039/c1cp21793c] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
|
23
|
Mannock DA, Lewis RN, McMullen TP, McElhaney RN. The effect of variations in phospholipid and sterol structure on the nature of lipid–sterol interactions in lipid bilayer model membranes. Chem Phys Lipids 2010; 163:403-48. [DOI: 10.1016/j.chemphyslip.2010.03.011] [Citation(s) in RCA: 119] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2009] [Revised: 03/13/2010] [Accepted: 03/27/2010] [Indexed: 01/30/2023]
|
24
|
Minogue S, Chu KME, Westover EJ, Covey DF, Hsuan JJ, Waugh MG. Relationship between phosphatidylinositol 4-phosphate synthesis, membrane organization, and lateral diffusion of PI4KIIalpha at the trans-Golgi network. J Lipid Res 2010; 51:2314-24. [PMID: 20388919 DOI: 10.1194/jlr.m005751] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Type II phosphatidylinositol 4-kinase IIalpha (PI4KIIalpha) is the dominant phosphatidylinositol kinase activity measured in mammalian cells and has important functions in intracellular vesicular trafficking. Recently PI4KIIalpha has been shown to have important roles in neuronal survival and tumorigenesis. This study focuses on the relationship between membrane cholesterol levels, phosphatidylinositol 4-phosphate (PI4P) synthesis, and PI4KIIalpha mobility. Enzyme kinetic measurements, sterol substitution studies, and membrane fragmentation analyses all revealed that cholesterol regulates PI4KIIalpha activity indirectly through effects on membrane structure. In particular, we found that cholesterol levels determined the distribution of PI4KIIalpha to biophysically distinct membrane domains. Imaging studies on cells expressing enhanced green fluorescent protein (eGFP)-tagged PI4KIIalpha demonstrated that cholesterol depletion resulted in morphological changes to the juxtanuclear membrane pool of the enzyme. Lateral membrane diffusion of eGFP-PI4KIIalpha was assessed by fluorescence recovery after photobleaching (FRAP) experiments, which revealed the existence of both mobile and immobile pools of the enzyme. Sterol depletion decreased the size of the mobile pool of PI4KIIalpha. Further measurements revealed that the reduction in the mobile fraction of PI4KIIalpha correlated with a loss of trans-Golgi network (TGN) membrane connectivity. We conclude that cholesterol modulates PI4P synthesis through effects on membrane organization and enzyme diffusion.
Collapse
Affiliation(s)
- Shane Minogue
- Department of Inflammation, Division of Medicine, University College London, Centre for Molecular Cell Biology, London, United Kingdom
| | | | | | | | | | | |
Collapse
|
25
|
Sorrenti A, Diociaiuti M, Corvaglia V, Chistolini P, Mancini G. Chiral recognition of dipeptides in Langmuir monolayers. ACTA ACUST UNITED AC 2009. [DOI: 10.1016/j.tetasy.2009.10.023] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
|
26
|
Alakoskela JM, Vitovic P, Kinnunen PKJ. Screening for the drug-phospholipid interaction: correlation to phospholipidosis. ChemMedChem 2009; 4:1224-51. [PMID: 19551800 DOI: 10.1002/cmdc.200900052] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Phospholipid bilayers represent a complex, anisotropic environment fundamentally different from bulk oil or octanol, for instance. Even "simple" drug association to phospholipid bilayers can only be fully understood if the slab-of-hydrocarbon approach is abandoned and the complex, anisotropic properties of lipid bilayers reflecting the chemical structures and organization of the constituent phospholipids are considered. The interactions of drugs with phospholipids are important in various processes, such as drug absorption, tissue distribution, and subcellular distribution. In addition, drug-lipid interactions may lead to changes in lipid-dependent protein activities, and further, to functional and morphological changes in cells, a prominent example being the phospholipidosis (PLD) induced by cationic amphiphilic drugs. Herein we briefly review drug-lipid interactions in general and the significance of these interactions in PLD in particular. We also focus on a potential causal connection between drug-induced PLD and steatohepatitis, which is induced by some cationic amphiphilic drugs.
Collapse
Affiliation(s)
- Juha-Matti Alakoskela
- Division of Biochemistry, Institute of Biomedicine, University of Helsinki, Haartmaninkatu 8, 00014 Helsinki, Finland.
| | | | | |
Collapse
|
27
|
Manna M, Mukhopadhyay C. Cause and effect of melittin-induced pore formation: a computational approach. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2009; 25:12235-12242. [PMID: 19754202 DOI: 10.1021/la902660q] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Melittin embedded in a palmitoyl oleyl phosphatidylcholine bilayer at a high peptide/lipid ratio (1:30) was simulated in the presence of explicit water and ions. The simulation results indicate the incipience of an ion-permeable water pore through collective membrane perturbation by bound peptides. The positively charged residues of melittin not only act as "anchors" but also disrupt the membrane, leading to cell lysis. A detailed analysis of the lipid tail order parameter profile depicts localized membrane perturbation. The lipids in the vicinity of the aqueous cavity adopt a tilted conformation, which allows local bilayer thinning. The prepore thus formed can be considered as the melittin-induced structural defects in the bilayer membrane. Because of the strong cationic nature, the melittin-induced prepore exhibits selectivity toward anions over cations. As Cl(-) ions entered into the prepore, they are electrostatically entrapped by positively charged residues located at its wall. The confined motion of the Cl(-) ions in the membrane interior is obvious from calculated diffusion coefficients. Moreover, reorientation of the local lipids occurs in such a way that few lipid heads along with peptide helices can line the surface of the penetrating aqueous phase. The flipping of lipids argued in favor of melittin-induced toroidal pore over a barrel-stave mechanism. Thus, our result provides atomistic level details of the mechanism of membrane disruption by antimicrobial peptide melittin.
Collapse
Affiliation(s)
- Moutusi Manna
- Department of Chemistry, University of Calcutta, 92, A. P. C. Road, Kolkata-700 009, India
| | | |
Collapse
|
28
|
Covey DF. ent-Steroids: novel tools for studies of signaling pathways. Steroids 2009; 74:577-85. [PMID: 19103212 PMCID: PMC2668732 DOI: 10.1016/j.steroids.2008.11.019] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/08/2008] [Revised: 11/21/2008] [Accepted: 11/24/2008] [Indexed: 12/24/2022]
Abstract
Membrane receptors are often modulated by steroids and it is necessary to distinguish the effects of steroids at these receptors from effects occurring at nuclear receptors. Additionally, it may also be mechanistically important to distinguish between direct effects caused by binding of steroids to membrane receptors and indirect effects on membrane receptor function caused by steroid perturbation of the membrane containing the receptor. In this regard, ent-steroids, the mirror images of naturally occurring steroids, are novel tools for distinguishing between these various actions of steroids. The review provides a background for understanding the different actions that can be expected of steroids and ent-steroids in biological systems, references for the preparation of ent-steroids, a short discussion about relevant forms of stereoisomerism and the requirements that need to be fulfilled for the interaction between two molecules to be enantioselective. The review then summarizes results of biophysical, biochemical and pharmacological studies published since 1992 in which ent-steroids have been used to investigate the actions of steroids in membranes and/or receptor-mediated signaling pathways.
Collapse
Affiliation(s)
- Douglas F Covey
- Department of Developmental Biology, Campus Box 8103, Washington Univ. in St. Louis, School of Medicine, 660 S. Euclid Ave., St. Louis, MO 63110, United States.
| |
Collapse
|
29
|
Ordering effects of cholesterol and its analogues. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2009; 1788:97-121. [DOI: 10.1016/j.bbamem.2008.08.022] [Citation(s) in RCA: 450] [Impact Index Per Article: 30.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/15/2008] [Revised: 08/27/2008] [Accepted: 08/31/2008] [Indexed: 12/12/2022]
|
30
|
Katona BW, Anant S, Covey DF, Stenson WF. Characterization of enantiomeric bile acid-induced apoptosis in colon cancer cell lines. J Biol Chem 2008; 284:3354-3364. [PMID: 19054763 DOI: 10.1074/jbc.m805804200] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Bile acids are steroid detergents that are toxic to mammalian cells at high concentrations; increased exposure to these steroids is pertinent in the pathogenesis of cholestatic disease and colon cancer. Understanding the mechanisms of bile acid toxicity and apoptosis, which could include nonspecific detergent effects and/or specific receptor activation, has potential therapeutic significance. In this report we investigate the ability of synthetic enantiomers of lithocholic acid (ent-LCA), chenodeoxycholic acid (ent-CDCA), and deoxycholic acid (ent-DCA) to induce toxicity and apoptosis in HT-29 and HCT-116 cells. Natural bile acids were found to induce more apoptotic nuclear morphology, cause increased cellular detachment, and lead to greater capase-3 and -9 cleavage compared with enantiomeric bile acids in both cell lines. In contrast, natural and enantiomeric bile acids showed similar effects on cellular proliferation. These data show that bile acid-induced apoptosis in HT-29 and HCT-116 cells is enantiospecific, hence correlated with the absolute configuration of the bile steroid rather than its detergent properties. The mechanism of LCA- and ent-LCA-induced apoptosis was also investigated in HT-29 and HCT-116 cells. These bile acids differentially activate initiator caspases-2 and -8 and induce cleavage of full-length Bid. LCA and ent-LCA mediated apoptosis was inhibited by both pan-caspase and selective caspase-8 inhibitors, whereas a selective caspase-2 inhibitor provided no protection. LCA also induced increased CD95 localization to the plasma membrane and generated increased reactive oxygen species compared with ent-LCA. This suggests that LCA/ent-LCA induce apoptosis enantioselectively through CD95 activation, likely because of increased reactive oxygen species generation, with resulting procaspase-8 cleavage.
Collapse
Affiliation(s)
- Bryson W Katona
- Department of Developmental Biology, Division of Gastroenterology, Washington University School of Medicine, St. Louis, Missouri 63110
| | - Shrikant Anant
- Department of Medicine, University of Oklahoma Heath Sciences Center, Oklahoma City, Oklahoma 73104
| | - Douglas F Covey
- Department of Developmental Biology, Division of Gastroenterology, Washington University School of Medicine, St. Louis, Missouri 63110
| | - William F Stenson
- Department of Medicine, Division of Gastroenterology, Washington University School of Medicine, St. Louis, Missouri 63110.
| |
Collapse
|
31
|
Christenson E, Merlin S, Saito M, Schlesinger P. Cholesterol effects on BAX pore activation. J Mol Biol 2008; 381:1168-83. [PMID: 18590739 DOI: 10.1016/j.jmb.2008.06.037] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2008] [Revised: 06/11/2008] [Accepted: 06/13/2008] [Indexed: 01/29/2023]
Abstract
The importance of BCL-2 family proteins in the control of cell death has been clearly established. One of the key members of this family, BAX, has soluble, membrane-bound, and membrane-integrated forms that are central to the regulation of apoptosis. Using purified monomeric human BAX, defined liposomes, and isolated human mitochondria, we have characterized the soluble to membrane transition and pore formation by this protein. For the purified protein, activation, but not oligomerization, is required for membrane binding. The transition to the membrane environment includes a binding step that is reversible and distinct from the membrane integration step. Oligomerization and pore activation occur after the membrane integration. In cells, BAX targets several intracellular membranes but notably does not target the plasma membrane while initiating apoptosis. When cholesterol was added to either the liposome bilayer or mitochondrial membranes, we observed increased binding but markedly reduced integration of BAX into both membranes. This cholesterol inhibition of membrane integration accounts for the reduction of BAX pore activation in liposomes and mitochondrial membranes. Our results indicate that the presence of cholesterol in membranes inhibits the pore-forming activity of BAX by reducing the ability of BAX to transition from a membrane-associated protein to a membrane-integral protein.
Collapse
Affiliation(s)
- Eric Christenson
- Department of Cell Biology and Physiology, Washington University School of Medicine, St. Louis, MO 63110, USA
| | | | | | | |
Collapse
|