1
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Vallée M. Advances in steroid research from the pioneering neurosteroid concept to metabolomics: New insights into pregnenolone function. Front Neuroendocrinol 2024; 72:101113. [PMID: 37993022 DOI: 10.1016/j.yfrne.2023.101113] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/22/2023] [Revised: 11/13/2023] [Accepted: 11/19/2023] [Indexed: 11/24/2023]
Abstract
Advances in neuroendocrinology have led to major discoveries since the 19th century, identifying adaptive loops for maintaining homeostasis. One of the most remarkable discoveries was the concept of neurosteroids, according to which the brain is not only a target but also a source of steroid production. The identification of new membrane steroid targets now underpins the neuromodulatory effects of neurosteroids such as pregnenolone, which is involved in functions mediated by the GPCR CB1 receptor. Structural analysis of steroids is a key feature of their interactions with the phospholipid membrane, receptors and resulting activity. Therefore, mass spectrometry-based methods have been developed to elucidate the metabolic pathways of steroids, the ultimate approach being metabolomics, which allows the identification of a large number of metabolites in a single sample. This approach should enable us to make progress in understanding the role of neurosteroids in the functioning of physiological and pathological processes.
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Affiliation(s)
- Monique Vallée
- University Bordeaux, INSERM, Neurocentre Magendie, U1215, F-33000 Bordeaux, France.
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2
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McMorrow K, Allahabadi S, Frazier L, Quigley R, Serrano B, Cole BJ. One to Two Days of Rest Is Recommended Before Returning to Sport After Intra-Articular Corticosteroid Injection in the High-Level Athlete. Arthrosc Sports Med Rehabil 2023; 5:100763. [PMID: 37560144 PMCID: PMC10407144 DOI: 10.1016/j.asmr.2023.100763] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2023] [Accepted: 06/13/2023] [Indexed: 08/11/2023] Open
Abstract
UNLABELLED Return to sport following a corticosteroid injection is a complex decision. Multiple considerations should be taken into account, including steroid dose and formulation, involvement of the affected joint in the activity, and intensity of the activity. Research investigating the adverse effects of corticosteroid injections with early initiation of high-intensity activity is limited and has produced mixed results. Rest following injections has typically been recommended to minimize both chondrotoxic effects and systemic absorption. Based on the current research and extensive experience treating professional athletes, we recommend 1 to 2 days of rest of the affected joint or region with a progressive increase of activity following a corticosteroid injection with possible benefits including maximizing the beneficial effects of the injection and a reduced systemic effect. LEVEL OF EVIDENCE Level V, expert opinion.
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Affiliation(s)
| | | | | | - Ryan Quigley
- Midwest Orthopaedics at Rush, Chicago, Illinois, U.S.A
| | | | - Brian J. Cole
- Midwest Orthopaedics at Rush, Chicago, Illinois, U.S.A
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3
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Cushman DM, Kobayashi JK, Wheelwright JC, English J, Monson N, Teramoto M, Dunn R, Lash M, Zarate M. Prospective Evaluation of Pain Flares and Time Until Pain Relief Following Musculoskeletal Corticosteroid Injections. Sports Health 2023; 15:227-233. [PMID: 35331061 PMCID: PMC9950997 DOI: 10.1177/19417381221076470] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
BACKGROUND Corticosteroid injections are used ubiquitously within musculoskeletal medicine. One of the most common side effects is a postinjection pain flare, though little is known regarding this phenomenon. HYPOTHESIS Some risk factors are related to postinjection pain flare following an ultrasound-guided corticosteroid injection. STUDY DESIGN Prospective clinical research study. LEVEL OF EVIDENCE Level 2. METHODS Patients undergoing ultrasound-guided corticosteroid injections in an academic orthopaedic and sports medicine clinic were approached to participate. Patients completed a survey immediately following their injection and again 2 weeks later, asking them about their pain and side effects. A postinjection pain flare was defined as an increase in pain, as defined by the patient. RESULTS A total of 140 patients completed the entirety of the study, with 29 (20.7%) patients reporting a flare of pain. There was a significant effect of younger age on the development of a pain flare after the injection, estimated as 5.5% decreased odds of developing a flare per year of age (P < 0.01). Gender, injection location, body mass index (BMI), preinjection pain, and corticosteroid type had no contributing effect. When patients obtained relief following the corticosteroid injection, 60.4% had improved pain within 3 days, whereas over 93.7% obtained relief within a week. CONCLUSION Pain flares seem to affect approximately 1 in 5 patients. With increasing age, the likelihood of postinjection pain flare becomes less likely. Sex, injection location, BMI, preinjection pain, and corticosteroid type do not seem to significantly relate to an increase in pain following injection. CLINICAL RELEVANCE Corticosteroid injections are common procedures in the orthopaedic and sports medicine settings. Younger patients can be counseled on the higher likelihood of a pain flare following a corticosteroid injection.
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Affiliation(s)
- Daniel M. Cushman
- Daniel M. Cushman, MD,
University of Utah, 590 Wakara Way, Salt Lake City, UT 84108 (
)
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4
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Wakileh W, Watanabe N, Suga K, Ikushima N, Kajimura N, Mitsuoka K, Okamoto Y, Umakoshi H. “Dispersibility and Surface Properties of Hydrocortisone-incorporated Self-Assemblies”. Colloids Surf A Physicochem Eng Asp 2023. [DOI: 10.1016/j.colsurfa.2023.131217] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/07/2023]
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5
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Synthesis of gold and copper bimetallic nanoclusters with papain for fluorescence detection of cortisone in biological samples. Anal Bioanal Chem 2023; 415:335-343. [PMID: 36355222 DOI: 10.1007/s00216-022-04412-w] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2022] [Revised: 10/15/2022] [Accepted: 10/28/2022] [Indexed: 11/11/2022]
Abstract
In this work, bimetallic gold and copper nanoclusters (Au-Cu NCs) were fabricated by using papain as a ligand. The as-synthesized papain-Au-Cu NCs displayed red fluorescence at 365 nm of UV lamp. The as-prepared papain-Au-Cu NCs display a strong fluorescence at 656 nm when excited at 390 nm. Papain encapsulated Au-Cu NCs exhibit distinct interaction site towards cortisone, which results red fluorescence "turn-off". Papain-Au-Cu NCs exhibited a rapid response and remarkable fluorescence quenching with the addition of cortisone as a biomarker. The developed probe is demonstrated for the quantification of cortisone by plotting the calibration graph between the fluorescence ratio (I0/I) and cortisone concentration (0.031-1.00 μM) with an impressive detection limit of 1.89 nM. Interestingly, the response of papain-Au-Cu NCs towards other biomarkers and common interfering species is quite silent, signifying the selectivity of papain-Au-Cu NCs for the detection of cortisone. The probe was successfully applied to assay cortisone biomarker in urine and plasma samples. More importantly, the analytical validation of the probe was assessed by assaying cortisone in intra- and inter-day, demonstrating papain-Au-Cu NCs could serve as promising probe for the rapid detection of cortisone in biological samples.
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6
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Islam MZ, Hossain SI, Deplazes E, Saha SC. Concentration-dependent cortisone adsorption and interaction with model lung surfactant monolayer. MOLECULAR SIMULATION 2022. [DOI: 10.1080/08927022.2022.2113397] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/15/2022]
Affiliation(s)
- Mohammad Zohurul Islam
- School of Mechanical and Mechatronic Engineering, University of Technology Sydney, Ultimo, Australia
| | - Sheikh I. Hossain
- School of Life Sciences, University of Technology Sydney, Ultimo, Australia
| | - Evelyne Deplazes
- School of Life Sciences, University of Technology Sydney, Ultimo, Australia
| | - Suvash C. Saha
- School of Mechanical and Mechatronic Engineering, University of Technology Sydney, Ultimo, Australia
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7
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Crowley J, Withana M, Deplazes E. The interaction of steroids with phospholipid bilayers and membranes. Biophys Rev 2022; 14:163-179. [PMID: 35340606 PMCID: PMC8921366 DOI: 10.1007/s12551-021-00918-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2021] [Accepted: 11/18/2021] [Indexed: 12/13/2022] Open
Abstract
Steroids are critical for various physiological processes and used to treat inflammatory conditions. Steroids act by two distinct pathways. The genomic pathway is initiated by the steroid binding to nuclear receptors while the non-genomic pathway involves plasma membrane receptors. It has been proposed that steroids might also act in a more indirect mechanism by altering biophysical properties of membranes. Yet, little is known about the effect of steroids on membranes, and steroid-membrane interactions are complex and challenging to characterise. The focus of this review is to outline what is currently known about the interactions of steroids with phospholipid bilayers and illustrate the complexity of these systems using cortisone and progesterone as the main examples. The combined findings from current work demonstrate that the hydrophobicity and planarity of the steroid core does not provide a consensus for steroid-membrane interactions. Even small differences in the substituents on the steroid core can result in significant changes in steroid-membrane interactions. Furthermore, steroid-induced changes in phospholipid bilayer properties are often dependent on steroid concentration and lipid composition. This complexity means that currently there is insufficient information to establish a reliable structure-activity relationship to describe the effect of steroids on membrane properties. Future work should address the challenge of connecting the findings from studying the effect of steroids on phospholipid bilayers to cell membranes. Insights from steroid-membrane interactions will benefit our understanding of normal physiology and assist drug development.
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Affiliation(s)
- Jackson Crowley
- School of Life Sciences, University of Technology Sydney, Ultimo, NSW 2007 Australia
| | - Minduli Withana
- School of Life Sciences, University of Technology Sydney, Ultimo, NSW 2007 Australia
| | - Evelyne Deplazes
- School of Life Sciences, University of Technology Sydney, Ultimo, NSW 2007 Australia
- School of Chemistry and Molecular Biosciences, University of Queensland, St Lucia, QLD 4072 Australia
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8
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Cha J, Hong S, Lee J, Gwak J, Kim M, Kim T, Hur J, Giesy JP, Khim JS. Novel polar AhR-active chemicals detected in sediments of an industrial area using effect-directed analysis based on in vitro bioassays with full-scan high resolution mass spectrometric screening. THE SCIENCE OF THE TOTAL ENVIRONMENT 2021; 779:146566. [PMID: 34030261 DOI: 10.1016/j.scitotenv.2021.146566] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/06/2020] [Revised: 02/22/2021] [Accepted: 03/14/2021] [Indexed: 06/12/2023]
Abstract
Studies investigating aryl hydrocarbon receptor (AhR)-active compounds in the environment typically focus on non- and mid-polar substances, such as PAHs; while, information on polar AhR agonists remains limited. Here, we identified polar AhR agonists in sediments collected from the inland creeks of an industrialized area (Lake Sihwa, Korea) using effect-directed analysis combined with full-scan screening analysis (FSA; using LC-QTOFMS). Strong AhR-mediated potencies were observed for the polar and latter fractions of RP-HPLC (F3.5-F3.8) from sediment organic extracts in the H4IIE-luc in vitro bioassays. FSA was performed on the corresponding fractions. Twenty-eight tentative AhR agonists were chosen using a five-step process. Toxicological confirmation using bioassay revealed that canrenone, rutaecarpine, ciprofloxacin, mepanipyrim, genistein, protopine, hydrocortisone, and medroxyprogesterone were significantly active. The relative potencies of these AhR-active compounds compared to that of benzo[a]pyrene ranged from 0.00002 to 2.0. Potency balance analysis showed that polar AhR agonists explained, on average, ~6% of total AhR-mediated potencies in samples. Some novel polar AhR agonists also exhibited endocrine-disrupting potentials capable of binding to estrogen and glucocorticoid receptors, as identified by QSAR modeling. In conclusion, the focused studies on distributions, sources, fate, and ecotoxicological effects of novel polar AhR agonists in the environment are necessary.
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Affiliation(s)
- Jihyun Cha
- Department of Ocean Environmental Sciences, Chungnam National University, Daejeon 34134, Republic of Korea
| | - Seongjin Hong
- Department of Ocean Environmental Sciences, Chungnam National University, Daejeon 34134, Republic of Korea.
| | - Junghyun Lee
- School of Earth and Environmental Sciences & Research Institute of Oceanography, Seoul National University, Seoul 08826, Republic of Korea
| | - Jiyun Gwak
- Department of Ocean Environmental Sciences, Chungnam National University, Daejeon 34134, Republic of Korea
| | - Mungi Kim
- Department of Ocean Environmental Sciences, Chungnam National University, Daejeon 34134, Republic of Korea
| | - Taewoo Kim
- School of Earth and Environmental Sciences & Research Institute of Oceanography, Seoul National University, Seoul 08826, Republic of Korea
| | - Jin Hur
- Department of Environment & Energy, Sejong University, Seoul 05006, Republic of Korea
| | - John P Giesy
- Department of Veterinary Biomedical Sciences & Toxicology Centre, University of Saskatchewan, Saskatoon, Saskatchewan S7N5B3, Canada; Department of Environmental Science, Baylor University, Waco, TX 76798-7266, United States
| | - Jong Seong Khim
- School of Earth and Environmental Sciences & Research Institute of Oceanography, Seoul National University, Seoul 08826, Republic of Korea.
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9
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Bider RC, Lluka T, Himbert S, Khondker A, Qadri SM, Sheffield WP, Rheinstädter MC. Stabilization of Lipid Membranes through Partitioning of the Blood Bag Plasticizer Di-2-ethylhexyl phthalate (DEHP). LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2020; 36:11899-11907. [PMID: 32903014 DOI: 10.1021/acs.langmuir.0c01964] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
The safe storage of blood is of fundamental importance to health care systems all over the world. Currently, plastic bags are used for the collection and storage of donated blood and are typically made of poly(vinyl chloride) (PVC) plasticized with di-2-ethylhexyl phthalate (DEHP). DEHP is known to migrate into packed red blood cells (RBC) and has been found to extend their shelf life. It has been speculated that DEHP incorporates itself into the RBC membrane and alters membrane properties, thereby reducing susceptibility to hemolysis and morphological deterioration. Here, we used high-resolution X-ray diffraction and molecular dynamics (MD) simulations to study the interaction between DEHP and model POPC lipid membranes at high (9 mol %) and low (1 mol %) concentrations of DEHP. At both concentrations, DEHP was found to spontaneously partition into the bilayer. At high concentrations, DEHP molecules were found to aggregate in the aqueous phase before inserting as clusters into the membrane. The presence of DEHP in the bilayers resulted in subtle, yet statistically significant, alterations in several membrane properties in both the X-ray diffraction experiments and MD simulations. DEHP led to (1) an increase of membrane width and (2) an increase in the area per lipid. It was also found to (3) increase the deuterium order parameter, however, (4) decrease membrane orientation, indicating the formation of thicker, stiffer membranes with increased local curvature. The observed effects of DEHP on lipid bilayers may help to better understand its effect on RBC membranes in increasing the longevity of stored blood by improving membrane stability.
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Affiliation(s)
- Renée-Claude Bider
- Department of Physics and Astronomy, McMaster University, 1280 Main Street West, Hamilton, Ontario L8S 4M1, Canada
- Origins Institute, McMaster University, Hamilton, Ontario L8S 4M1, Canada
| | - Telmah Lluka
- Department of Physics and Astronomy, McMaster University, 1280 Main Street West, Hamilton, Ontario L8S 4M1, Canada
- Origins Institute, McMaster University, Hamilton, Ontario L8S 4M1, Canada
| | - Sebastian Himbert
- Department of Physics and Astronomy, McMaster University, 1280 Main Street West, Hamilton, Ontario L8S 4M1, Canada
- Origins Institute, McMaster University, Hamilton, Ontario L8S 4M1, Canada
| | - Adree Khondker
- Department of Physics and Astronomy, McMaster University, 1280 Main Street West, Hamilton, Ontario L8S 4M1, Canada
- Origins Institute, McMaster University, Hamilton, Ontario L8S 4M1, Canada
| | - Syed M Qadri
- Faculty of Health Sciences, Ontario Tech University, Oshawa, Ontario L1G 0C5, Canada
| | - William P Sheffield
- Department of Pathology and Molecular Medicine, McMaster University, Hamilton, Ontario L8S 4M1, Canada
- Centre for Innovation, Canadian Blood Services, Hamilton, Ontario L8S 4M1, Canada
| | - Maikel C Rheinstädter
- Department of Physics and Astronomy, McMaster University, 1280 Main Street West, Hamilton, Ontario L8S 4M1, Canada
- Origins Institute, McMaster University, Hamilton, Ontario L8S 4M1, Canada
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10
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Cholak E, Bugge K, Khondker A, Gauger K, Pedraz-Cuesta E, Pedersen ME, Bucciarelli S, Vestergaard B, Pedersen SF, Rheinstädter MC, Langkilde AE, Kragelund BB. Avidity within the N-terminal anchor drives α-synuclein membrane interaction and insertion. FASEB J 2020; 34:7462-7482. [PMID: 32277854 DOI: 10.1096/fj.202000107r] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2020] [Revised: 03/02/2020] [Accepted: 03/17/2020] [Indexed: 12/25/2022]
Abstract
In the brain, α-synuclein (aSN) partitions between free unbound cytosolic and membrane bound forms modulating both its physiological and pathological role and complicating its study due to structural heterogeneity. Here, we use an interdisciplinary, synergistic approach to characterize the properties of aSN:lipid mixtures, isolated aSN:lipid co-structures, and aSN in mammalian cells. Enabled by the isolation of the membrane-bound state, we show that within the previously described N-terminal membrane anchor, membrane interaction relies both on an N-terminal tail (NTT) head group layer insertion of 14 residues and a folded-upon-binding helix at the membrane surface. Both binding events must be present; if, for example, the NTT insertion is lost, the membrane affinity of aSN is severely compromised and formation of aSN:lipid co-structures hampered. In mammalian cells, compromised cooperativity results in lowered membrane association. Thus, avidity within the N-terminal anchor couples N-terminal insertion and helical surface binding, which is crucial for aSN membrane interaction and cellular localization, and may affect membrane fusion.
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Affiliation(s)
- Ersoy Cholak
- Department of Drug Design and Pharmacology, University of Copenhagen, Copenhagen, Denmark
| | - Katrine Bugge
- Structural Biology and NMR Laboratory, The Linderstrøm-Lang Centre for Protein Science and Department of Biology, University of Copenhagen, Copenhagen, Denmark
| | - Adree Khondker
- Department of Physics and Astronomy, McMaster University, Hamilton, ON, Canada
| | - Kimmie Gauger
- Section for Cell Biology and Physiology, Department of Biology, University of Copenhagen, Copenhagen, Denmark
| | - Elena Pedraz-Cuesta
- Section for Cell Biology and Physiology, Department of Biology, University of Copenhagen, Copenhagen, Denmark
| | | | - Saskia Bucciarelli
- Department of Drug Design and Pharmacology, University of Copenhagen, Copenhagen, Denmark
| | - Bente Vestergaard
- Department of Drug Design and Pharmacology, University of Copenhagen, Copenhagen, Denmark
| | - Stine F Pedersen
- Section for Cell Biology and Physiology, Department of Biology, University of Copenhagen, Copenhagen, Denmark
| | | | - Annette Eva Langkilde
- Department of Drug Design and Pharmacology, University of Copenhagen, Copenhagen, Denmark
| | - Birthe B Kragelund
- Structural Biology and NMR Laboratory, The Linderstrøm-Lang Centre for Protein Science and Department of Biology, University of Copenhagen, Copenhagen, Denmark
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11
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Saem S, Shahid O, Khondker A, Moran-Hidalgo C, Rheinstädter MC, Moran-Mirabal J. Benchtop-fabricated lipid-based electrochemical sensing platform for the detection of membrane disrupting agents. Sci Rep 2020; 10:4595. [PMID: 32165701 PMCID: PMC7067837 DOI: 10.1038/s41598-020-61561-7] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2019] [Accepted: 02/28/2020] [Indexed: 11/22/2022] Open
Abstract
There are increasing concerns about the danger that water-borne pathogens and pollutants pose to the public. Of particular importance are those that disrupt the plasma membrane, since loss of membrane integrity can lead to cell death. Currently, quantitative assays to detect membrane-disrupting (lytic) agents are done offsite, leading to long turnaround times and high costs, while existing colorimetric point-of-need solutions often sacrifice sensitivity. Thus, portable and highly sensitive solutions are needed to detect lytic agents for health and environmental monitoring. Here, a lipid-based electrochemical sensing platform is introduced to rapidly detect membrane-disrupting agents. The platform combines benchtop fabricated microstructured electrodes (MSEs) with lipid membranes. The sensing mechanism of the lipid-based platform relies on stacked lipid membranes serving as passivating layers that when disrupted generate electrochemical signals proportional to the membrane damage. The MSE topography, membrane casting and annealing conditions were optimized to yield the most reproducible and sensitive devices. We used the sensors to detect membrane-disrupting agents sodium dodecyl sulfate and Polymyxin-B within minutes and with limits of detection in the ppm regime. This study introduces a platform with potential for the integration of complex membranes on MSEs towards the goal of developing Membrane-on-Chip sensing devices.
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Affiliation(s)
- Sokunthearath Saem
- McMaster University, Department of Chemistry and Chemical Biology, Hamilton, L8S 4L8, Canada
| | - Osama Shahid
- McMaster University, Department of Chemistry and Chemical Biology, Hamilton, L8S 4L8, Canada
| | - Adree Khondker
- McMaster University, Department of Physics and Astronomy, Hamilton, L8S 4L8, Canada
| | - Camila Moran-Hidalgo
- McMaster University, Department of Chemistry and Chemical Biology, Hamilton, L8S 4L8, Canada
| | | | - Jose Moran-Mirabal
- McMaster University, Department of Chemistry and Chemical Biology, Hamilton, L8S 4L8, Canada.
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12
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Khondker A, Hub JS, Rheinstädter MC. Steroid-steroid interactions in biological membranes: Cholesterol and cortisone. Chem Phys Lipids 2019; 221:193-197. [PMID: 30951711 DOI: 10.1016/j.chemphyslip.2019.04.003] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2018] [Revised: 03/27/2019] [Accepted: 04/01/2019] [Indexed: 11/17/2022]
Abstract
Steroid flares are common side effects associated with corticosteroid treatment, and have been recently theorized to be a consequence of drug crystallization. It was previously reported that the lipid bilayer can promote crystallization of cortisone at high local concentrations. Here, we studied the effect of cholesterol on this membrane induced cortisone crystallization. By combining x-ray diffraction and Molecular Dynamics simulations we observe that that the presence of cholesterol suppresses cortisone-induced membrane thinning and cortisone transnucleation. Cortisone located in the head-tail interface of the membranes also in the presence of cholesterol. The cholesterol molecules were found to be tilted and displaced towards the bilayer center as function of cortisone concentration, away from their canonical position. Our results show that membrane cholesterol may play an important role in the ability of lipid bilayers to catalyze the formation of corticosteroid crystallites.
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Affiliation(s)
- Adree Khondker
- Department of Physics and Astronomy, McMaster University, Hamilton, Ontario, Canada; Origins Institute, McMaster University, Hamilton, Ontario, Canada
| | - Jochen S Hub
- Theoretical Physics and Center for Biophysics, Saarland University, Saarbrücken, Germany
| | - Maikel C Rheinstädter
- Department of Physics and Astronomy, McMaster University, Hamilton, Ontario, Canada; Origins Institute, McMaster University, Hamilton, Ontario, Canada.
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13
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Schmidt A, Alsop RJ, Rimal R, Lenzig P, Joussen S, Gervasi NN, Khondker A, Gründer S, Rheinstädter MC, Wiemuth D. Modulation of DEG/ENaCs by Amphiphiles Suggests Sensitivity to Membrane Alterations. Biophys J 2019; 114:1321-1335. [PMID: 29590590 DOI: 10.1016/j.bpj.2018.01.028] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2017] [Revised: 01/22/2018] [Accepted: 01/26/2018] [Indexed: 12/25/2022] Open
Abstract
The bile acid-sensitive ion channel is activated by amphiphilic substances such as bile acids or artificial detergents via membrane alterations; however, the mechanism of membrane sensitivity of the bile acid-sensitive ion channel is not known. It has also not been systematically investigated whether other members of the degenerin/epithelial Na+ channel (DEG/ENaC) gene family are affected by amphiphilic compounds. Here, we show that DEG/ENaCs ASIC1a, ASIC3, ENaC, and the purinergic receptor P2X2 are modulated by a large number of different, structurally unrelated amphiphilic substances, namely the detergents N-lauroylsarcosine, Triton X-100, and β-octylglucoside; the fenamate flufenamic acid; the antipsychotic drug chlorpromazine; the natural phenol resveratrol; the chili pepper compound capsaicin; the loop diuretic furosemide; and the antiarrythmic agent verapamil. We determined the modification of membrane properties using large-angle x-ray diffraction experiments on model lipid bilayers, revealing that the amphiphilic compounds are positioned in a characteristic fashion either in the lipid tail group region or in the lipid head group region, demonstrating that they perturbed the membrane structure. Collectively, our results show that DEG/ENaCs and structurally related P2X receptors are modulated by diverse amphiphilic molecules. Furthermore, they suggest alterations of membrane properties by amphiphilic compounds as a mechanism contributing to modulation.
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Affiliation(s)
- Axel Schmidt
- Institute of Physiology, RWTH Aachen University, Aachen, Germany
| | - Rick J Alsop
- Department of Physics and Astronomy, McMaster University, Hamilton, Ontario, Canada
| | - Rahul Rimal
- Institute of Physiology, RWTH Aachen University, Aachen, Germany
| | - Pia Lenzig
- Institute of Physiology, RWTH Aachen University, Aachen, Germany
| | - Sylvia Joussen
- Institute of Physiology, RWTH Aachen University, Aachen, Germany
| | - Natalie N Gervasi
- Department of Physics and Astronomy, McMaster University, Hamilton, Ontario, Canada
| | - Adree Khondker
- Department of Physics and Astronomy, McMaster University, Hamilton, Ontario, Canada
| | - Stefan Gründer
- Institute of Physiology, RWTH Aachen University, Aachen, Germany
| | | | - Dominik Wiemuth
- Institute of Physiology, RWTH Aachen University, Aachen, Germany.
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14
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Khondker A, Dhaliwal AK, Saem S, Mahmood A, Fradin C, Moran-Mirabal J, Rheinstädter MC. Membrane charge and lipid packing determine polymyxin-induced membrane damage. Commun Biol 2019; 2:67. [PMID: 30793045 PMCID: PMC6379423 DOI: 10.1038/s42003-019-0297-6] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2018] [Accepted: 01/11/2019] [Indexed: 01/14/2023] Open
Abstract
With the advent of polymyxin B (PmB) resistance in bacteria, the mechanisms for mcr-1 resistance are of crucial importance in the design of novel therapeutics. The mcr-1 phenotype is known to decrease membrane charge and increase membrane packing by modification of the bacterial outer membrane. We used X-ray diffraction, Molecular Dynamics simulations, electrochemistry, and leakage assays to determine the location of PmB in different membranes and assess membrane damage. By varying membrane charge and lipid tail packing independently, we show that increasing membrane surface charge promotes penetration of PmB and membrane damage, whereas increasing lipid packing decreases penetration and damage. The penetration of the PmB molecules is well described by a phenomenological model that relates an attractive electrostatic and a repulsive force opposing insertion due to increased membrane packing. The model applies well to several gram-negative bacterial strains and may be used to predict resistance strength.
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Affiliation(s)
- Adree Khondker
- Department of Physics and Astronomy, McMaster University, Hamilton, ON, Canada
- Origins Institute, McMaster University, Hamilton, ON, Canada
| | - Alexander K Dhaliwal
- Department of Physics and Astronomy, McMaster University, Hamilton, ON, Canada
- Origins Institute, McMaster University, Hamilton, ON, Canada
| | - Sokunthearath Saem
- Department of Chemistry and Chemical Biology, McMaster University, Hamilton, ON, Canada
| | - Ahmad Mahmood
- Department of Physics and Astronomy, McMaster University, Hamilton, ON, Canada
| | - Cécile Fradin
- Department of Physics and Astronomy, McMaster University, Hamilton, ON, Canada
- Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, ON, Canada
| | - Jose Moran-Mirabal
- Department of Chemistry and Chemical Biology, McMaster University, Hamilton, ON, Canada
| | - Maikel C Rheinstädter
- Department of Physics and Astronomy, McMaster University, Hamilton, ON, Canada.
- Origins Institute, McMaster University, Hamilton, ON, Canada.
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15
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Sun S, Sendecki AM, Pullanchery S, Huang D, Yang T, Cremer PS. Multistep Interactions between Ibuprofen and Lipid Membranes. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2018; 34:10782-10792. [PMID: 30148644 DOI: 10.1021/acs.langmuir.8b01878] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Ibuprofen (IBU) interacts with phosphatidylcholine membranes in three distinct steps as a function of concentration. In a first step (<10 μM), IBU electrostatically adsorbs to the lipid headgroups and gradually decreases the interfacial potential. This first step helps to facilitate the second step (10-300 μM), in which hydrophobic insertion of the drug occurs. The second step disrupts the packing of the lipid acyl chains and expands the area per lipid. In a final step, above 300 μM IBU, the lipid membrane begins to solubilize, resulting in a detergent-like effect. The results described herein were obtained by a combination of fluorescence binding assays, vibrational sum frequency spectroscopy, and Langmuir monolayer compression experiments. By introducing trimethylammonium-propane, phosphatidylglycerol, and phosphatidylethanolamine lipids as well as cholesterol, we demonstrated that both the chemistry of the lipid headgroups and the packing of lipid acyl chains can substantially influence the interactions between IBU and the membranes. Moreover, different membrane chemistries can alter particular steps in the binding interaction.
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Affiliation(s)
- Simou Sun
- Department of Chemistry , Penn State University , University Park , State College , Pennsylvania 16802 , United States
| | - Anne M Sendecki
- Department of Chemistry , Penn State University , University Park , State College , Pennsylvania 16802 , United States
| | - Saranya Pullanchery
- Department of Chemistry , Penn State University , University Park , State College , Pennsylvania 16802 , United States
| | - Da Huang
- Department of Chemistry , Penn State University , University Park , State College , Pennsylvania 16802 , United States
| | - Tinglu Yang
- Department of Chemistry , Penn State University , University Park , State College , Pennsylvania 16802 , United States
| | - Paul S Cremer
- Department of Chemistry , Penn State University , University Park , State College , Pennsylvania 16802 , United States
- Department of Biochemistry and Molecular Biology , Penn State University , State College , Pennsylvania 16802 , United States
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16
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Yousefpour A, Amjad-Iranagh S, Goharpey F, Modarress H. Effect of drug amlodipine on the charged lipid bilayer cell membranes DMPS and DMPS + DMPC: a molecular dynamics simulation study. EUROPEAN BIOPHYSICS JOURNAL: EBJ 2018; 47:939-950. [PMID: 29971510 DOI: 10.1007/s00249-018-1317-z] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/24/2018] [Revised: 05/19/2018] [Accepted: 06/26/2018] [Indexed: 01/03/2023]
Abstract
In this work, the effects of the anti-hypertensive drug amlodipine in native and PEGylated forms on the malfunctioning of negatively charged lipid bilayer cell membranes constructed from DMPS or DMPS + DMPC were studied by molecular dynamics simulation. The obtained results indicate that amlodipine alone aggregates and as a result its diffusion into the membrane is retarded. In addition, due to their large size aggregates of the drug can damage the cell, rupturing the cell membrane. It is shown that PEGylation of amlodipine prevents this aggregation and facilitates its diffusion into the lipid membrane. The interaction of the drug with negatively charged membranes in the presence of an aqueous solution of NaCl, as the medium, is investigated and its effects on the membrane are considered by evaluating the structural properties of the membrane such as area per lipid, thickness, lipid chain order and electrostatic potential difference between bulk solution and lipid bilayer surface. The effect of these parameters on the diffusion of the drug into the cell is critically examined and discussed.
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Affiliation(s)
- Abbas Yousefpour
- Department of Chemical Engineering, Amirkabir University of Technology (Tehran Polytechnic), 424 Hafez Ave, Tehran, P.O. Box 15875-4413, Iran
| | - Sepideh Amjad-Iranagh
- Department of Chemical Engineering, Amirkabir University of Technology (Tehran Polytechnic), 424 Hafez Ave, Tehran, P.O. Box 15875-4413, Iran
| | - Fatemeh Goharpey
- Department of Polymer Engineering, Amirkabir University of Technology (Tehran Polytechnic), Tehran, Iran
| | - Hamid Modarress
- Department of Chemical Engineering, Amirkabir University of Technology (Tehran Polytechnic), 424 Hafez Ave, Tehran, P.O. Box 15875-4413, Iran.
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17
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Kaddah S, Khreich N, Kaddah F, Khrouz L, Charcosset C, Greige-Gerges H. Corticoids modulate liposome membrane fluidity and permeability depending on membrane composition and experimental protocol design. Biochimie 2018; 153:33-45. [PMID: 29935242 DOI: 10.1016/j.biochi.2018.06.011] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2018] [Accepted: 06/15/2018] [Indexed: 01/22/2023]
Abstract
Given that literature data may give inconsistent results on the effect of a drug on lipid membrane properties, this work aims to investigate the impact of the liposome composition and experimental protocol design on glucocorticoids (GRs: cortisol, cortisone, fludrocortisone acetate, methylprednisolone, prednisolone and prednisone)-modulating membrane fluidity and permeability. GRs-loaded liposomes consisting of dipalmitoylphosphatidylcholine (DPPC) and cholesterol (CHOL) were prepared by reverse phase evaporation technique (REV) at DPPC:CHOL:GR molar ratios of 100:100:2.5, and 100:100:10. The formulations were characterized for their size and homogeneity, encapsulation efficiency and loading rates of GRs, incorporation rates and loading rates of DPPC and CHOL. Changes in DPPC membrane fluidity (CHOL% 0, 10, 20, 30 and 100) after exposure to methylprednisolone were monitored by using 5- and 16-doxyl stearic acids (DSA) as spin probes. For permeability studies, the above-mentioned GRs-loaded liposomes and the preformed liposomes exposed to GRs (2.5 mol%) were compared for the leakage of an encapsulated fluorescent dye, sulforhodamine B (SRB), at 37 °C in buffer (pH 7.5) containing NaCl. The SRB release kinetics were analyzed by the Higuchi model for two release phases (from 0 to 10 h, and from 10 to 48 h). All formulations exhibited a monodispersed size distribution of liposomes with a mean particle value close to 0.4 μm, also the DPPC and CHOL were highly incorporated (>95%). High loading rate values of DPPC and CHOL were also obtained. Except for fludrocortisone acetate (51%) and prednisolone (77%), high loading rate values of GRs were obtained (>81%). Fluidity and permeability studies showed that the GR concentration, CHOL content, experimental protocol design including the period of incubation represent critical parameters to be considered in analyzing the effect of drugs on the membrane properties.
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Affiliation(s)
- Samar Kaddah
- Bioactive Molecules Research Laboratory, Faculty of Sciences, Lebanese University, Lebanon; Laboratoire d'Automatique et de Génie des Procédés (LAGEP), Université Claude Bernard, Lyon 1, France
| | - Nathalie Khreich
- Bioactive Molecules Research Laboratory, Faculty of Sciences, Lebanese University, Lebanon
| | - Fouad Kaddah
- École Supérieure d'ingénieurs de Beyrouth, Université Saint Joseph, Beyrouth, Mar Roukoz-Dekwaneh, Lebanon
| | - Lhoussain Khrouz
- Laboratoire de Chimie, École Normale Supérieure de Lyon (ENS), Université Claude Bernard, Lyon 1, France
| | - Catherine Charcosset
- Laboratoire d'Automatique et de Génie des Procédés (LAGEP), Université Claude Bernard, Lyon 1, France
| | - Hélène Greige-Gerges
- Bioactive Molecules Research Laboratory, Faculty of Sciences, Lebanese University, Lebanon.
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18
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Khondker A, Malenfant DJ, Dhaliwal AK, Rheinstädter MC. Carbapenems and Lipid Bilayers: Localization, Partitioning, and Energetics. ACS Infect Dis 2018; 4:926-935. [PMID: 29582993 DOI: 10.1021/acsinfecdis.7b00156] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Carbapenems are broad-spectrum antibiotics used today to treat otherwise antibiotic resistant bacteria. As their target transpeptidase is located within the periplasm of the Gram-negative bacteria, they can participate in nonspecific interactions between the inner leaflet of the outer membrane and the outer leaflet of the inner membrane. We, therefore, studied the interaction of the four most clinically relevant carbapenems, namely, imipenem, doripenem, ertapenem, and meropenem, with model phospholipid bilayers made of 1,2-dimyristoyl- sn-glycero-3-phosphocholine (DMPC) using molecular dynamics (MD) simulations and X-ray diffraction at low and high concentration of the drugs corresponding to 1 and 8 mol % (with respect to the number of membrane lipids). Membrane solubility was found to decrease from imipenem to doripenem, ertapenem, and finally meropenem. At low concentrations, membrane insertion was found to be a two step process, where the drugs first adsorb to the lipid head groups before inserting through a rotation of the molecule. At higher drug concentrations, the molecules were found to form aggregates in the aqueous phase before making contact with the membranes and spontaneously inserting into the bilayers. Two populations of imipenem were found: in the headgroup at ∼17 Å from the bilayer center and an inserted population at z-values of about 7 Å. Other carbapenems were found to localize in the tail groups with meropenem at ∼10 Å, doripenem at ∼8 Å, and ertapenem at ∼8 Å. The observed membrane solubility of carbapenems can potentially impact the availability of the drug to the target penicillin-binding proteins, potentially affecting their clinical efficacy.
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Affiliation(s)
- Adree Khondker
- Department of Physics and Astronomy, McMaster University, 1280 Main Street West, Hamilton, Ontario L8S 4M1, Canada
- Origins Institute, McMaster University, Hamilton, Ontario L8S 4M1, Canada
| | - Dylan J. Malenfant
- Department of Physics and Astronomy, McMaster University, 1280 Main Street West, Hamilton, Ontario L8S 4M1, Canada
- Origins Institute, McMaster University, Hamilton, Ontario L8S 4M1, Canada
| | - Alexander K. Dhaliwal
- Department of Physics and Astronomy, McMaster University, 1280 Main Street West, Hamilton, Ontario L8S 4M1, Canada
- Origins Institute, McMaster University, Hamilton, Ontario L8S 4M1, Canada
| | - Maikel C. Rheinstädter
- Department of Physics and Astronomy, McMaster University, 1280 Main Street West, Hamilton, Ontario L8S 4M1, Canada
- Origins Institute, McMaster University, Hamilton, Ontario L8S 4M1, Canada
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19
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Alsop RJ, Dhaliwal A, Rheinstädter MC. Curcumin Protects Membranes through a Carpet or Insertion Model Depending on Hydration. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2017; 33:8516-8524. [PMID: 28548854 DOI: 10.1021/acs.langmuir.7b01562] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Curcumin is the main ingredient in turmeric, a common Indian spice. Curcumin shows a broad spectrum of effects, including anti-Alzheimer's and antioxidant properties. An interaction between curcumin and lipid membranes has been speculated as the root cause of this activity, and the molecule is often proposed to protect the bilayer. However, the detailed molecular mechanism of this protection is disputed. There is evidence that curcumin either (a) lies flat on the bilayer and provides a "carpet" for protection by forming a steric barrier, or (b) inserts into the membrane and stiffens tails, thereby protecting against peptide insertion. We studied the interaction between curcumin and 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) bilayers at different concentrations using high-resolution X-ray diffraction and molecular dynamics (MD) computer simulations. We observed curcumin molecules forming a carpet in dehydrated bilayers, whereas in hydrated membranes the curcumin molecules were found to insert into the bilayers. From calculations of the potential of mean force (PMF), we find two minima, a metastable state in the headgroup region, at |z| ≈ 22 Å, and a global minimum in the hydrophobic membrane core, at |z| ≈ 9 Å. The population of the two states depends on membrane hydration. Experiments may thus observe curcumin in a carpet or inserted position, depending on the osmotic pressure conditions created, for instance, by salts, buffer solutions, substrates, or macromolecular solutes. In the carpet model, curcumin dehydrates lipid bilayers and decreases fluidity. When inserted, curcumin leads to a further fluidification of the membranes and an increase in tail fluctuations, contrary to cholesterol's condensing effect.
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Affiliation(s)
- Richard J Alsop
- Department of Physics and Astronomy, McMaster University , Hamilton, Ontario L8S 4M1, Canada
| | - Alexander Dhaliwal
- Department of Physics and Astronomy, McMaster University , Hamilton, Ontario L8S 4M1, Canada
| | - Maikel C Rheinstädter
- Department of Physics and Astronomy, McMaster University , Hamilton, Ontario L8S 4M1, Canada
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20
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The Molecular Structure of Human Red Blood Cell Membranes from Highly Oriented, Solid Supported Multi-Lamellar Membranes. Sci Rep 2017; 7:39661. [PMID: 28045119 PMCID: PMC5206716 DOI: 10.1038/srep39661] [Citation(s) in RCA: 45] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2016] [Accepted: 11/24/2016] [Indexed: 12/30/2022] Open
Abstract
We prepared highly oriented, multi-lamellar stacks of human red blood cell (RBC) membranes applied on silicon wafers. RBC ghosts were prepared by hemolysis and applied onto functionalized silicon chips and annealed into multi-lamellar RBC membranes. High resolution X-ray diffraction was used to determine the molecular structure of the stacked membranes. We present direct experimental evidence that these RBC membranes consist of nanometer sized domains of integral coiled-coil peptides, as well as liquid ordered (lo) and liquid disordered (ld) lipids. Lamellar spacings, membrane and hydration water layer thicknesses, areas per lipid tail and domain sizes were determined. The common drug aspirin was added to the RBC membranes and found to interact with RBC membranes and preferably partition in the head group region of the lo domain leading to a fluidification of the membranes, i.e., a thinning of the bilayers and an increase in lipid tail spacing. Our results further support current models of RBC membranes as patchy structures and provide unprecedented structural details of the molecular organization in the different domains.
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21
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Lopes D, Jakobtorweihen S, Nunes C, Sarmento B, Reis S. Shedding light on the puzzle of drug-membrane interactions: Experimental techniques and molecular dynamics simulations. Prog Lipid Res 2017; 65:24-44. [DOI: 10.1016/j.plipres.2016.12.001] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2016] [Revised: 11/30/2016] [Accepted: 12/03/2016] [Indexed: 12/20/2022]
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22
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Khondker A, Dhaliwal A, Alsop RJ, Tang J, Backholm M, Shi AC, Rheinstädter MC. Partitioning of caffeine in lipid bilayers reduces membrane fluidity and increases membrane thickness. Phys Chem Chem Phys 2017; 19:7101-7111. [DOI: 10.1039/c6cp08104e] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Caffeine partitions in lipid membranes in the head to tail interface and leads to a thickening and defluidification.
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Affiliation(s)
- Adree Khondker
- Department of Physics and Astronomy
- McMaster University
- Hamilton
- Canada
| | | | - Richard J. Alsop
- Department of Physics and Astronomy
- McMaster University
- Hamilton
- Canada
| | - Jennifer Tang
- Department of Physics and Astronomy
- McMaster University
- Hamilton
- Canada
| | - Matilda Backholm
- Department of Physics and Astronomy
- McMaster University
- Hamilton
- Canada
- Department of Applied Physics
| | - An-Chang Shi
- Department of Physics and Astronomy
- McMaster University
- Hamilton
- Canada
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23
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Schmidt A, Löhrer D, Alsop RJ, Lenzig P, Oslender-Bujotzek A, Wirtz M, Rheinstädter MC, Gründer S, Wiemuth D. A Cytosolic Amphiphilic α-Helix Controls the Activity of the Bile Acid-sensitive Ion Channel (BASIC). J Biol Chem 2016; 291:24551-24565. [PMID: 27679529 DOI: 10.1074/jbc.m116.756437] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2016] [Revised: 09/19/2016] [Indexed: 12/22/2022] Open
Abstract
The bile acid-sensitive ion channel (BASIC) is a member of the degenerin/epithelial Na+ channel (Deg/ENaC) family of ion channels. It is mainly found in bile duct epithelial cells, the intestinal tract, and the cerebellum and is activated by alterations of its membrane environment. Bile acids, one class of putative physiological activators, exert their effect by changing membrane properties, leading to an opening of the channel. The physiological function of BASIC, however, is unknown. Deg/ENaC channels are characterized by a trimeric subunit composition. Each subunit is composed of two transmembrane segments, which are linked by a large extracellular domain. The termini of the channels protrude into the cytosol. Many Deg/ENaC channels contain regulatory domains and sequence motifs within their cytosolic domains. In this study, we show that BASIC contains an amphiphilic α-helical structure within its N-terminal domain. This α-helix binds to the cytosolic face of the plasma membrane and stabilizes a closed state. Truncation of this domain renders the channel hyperactive. Collectively, we identify a cytoplasmic domain, unique to BASIC, that controls channel activity via membrane interaction.
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Affiliation(s)
- Axel Schmidt
- From the Institute of Physiology, RWTH Aachen University, D-52074 Aachen, Germany and
| | - Daniel Löhrer
- From the Institute of Physiology, RWTH Aachen University, D-52074 Aachen, Germany and
| | - Richard J Alsop
- the Department of Physics and Astronomy, McMaster University, Hamilton, Ontario L8S 4M1, Canada
| | - Pia Lenzig
- From the Institute of Physiology, RWTH Aachen University, D-52074 Aachen, Germany and
| | | | - Monika Wirtz
- From the Institute of Physiology, RWTH Aachen University, D-52074 Aachen, Germany and
| | - Maikel C Rheinstädter
- the Department of Physics and Astronomy, McMaster University, Hamilton, Ontario L8S 4M1, Canada
| | - Stefan Gründer
- From the Institute of Physiology, RWTH Aachen University, D-52074 Aachen, Germany and
| | - Dominik Wiemuth
- From the Institute of Physiology, RWTH Aachen University, D-52074 Aachen, Germany and.
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