1
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Potier-Cartereau M, Raoul W, Weber G, Mahéo K, Rapetti-Mauss R, Gueguinou M, Buscaglia P, Goupille C, Le Goux N, Abdoul-Azize S, Lecomte T, Fromont G, Chantome A, Mignen O, Soriani O, Vandier C. Potassium and Calcium Channel Complexes as Novel Targets for Cancer Research. Rev Physiol Biochem Pharmacol 2020; 183:157-176. [PMID: 32767122 DOI: 10.1007/112_2020_24] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
The intracellular Ca2+ concentration is mainly controlled by Ca2+ channels. These channels form complexes with K+ channels, which function to amplify Ca2+ flux. In cancer cells, voltage-gated/voltage-dependent Ca2+ channels and non-voltage-gated/voltage-independent Ca2+ channels have been reported to interact with K+ channels such as Ca2+-activated K+ channels and voltage-gated K+ channels. These channels are activated by an increase in cytosolic Ca2+ concentration or by membrane depolarization, which induces membrane hyperpolarization, increasing the driving force for Ca2+ flux. These complexes, composed of K+ and Ca2+ channels, are regulated by several molecules including lipids (ether lipids and cholesterol), proteins (e.g. STIM), receptors (e.g. S1R/SIGMAR1), and peptides (e.g. LL-37) and can be targeted by monoclonal antibodies, making them novel targets for cancer research.
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Affiliation(s)
| | - William Raoul
- N2C UMR 1069, University of Tours, INSERM, Tours, France
| | - Gunther Weber
- N2C UMR 1069, University of Tours, INSERM, Tours, France
| | - Karine Mahéo
- N2C UMR 1069, University of Tours, INSERM, Tours, France
| | | | | | - Paul Buscaglia
- LBAI UMR 1227, University of Brest, INSERM, Brest, France
| | - Caroline Goupille
- N2C UMR 1069, University of Tours, INSERM, CHRU de Tours, Tours, France
| | - Nelig Le Goux
- LBAI UMR 1227, University of Brest, INSERM, Brest, France
| | | | - Thierry Lecomte
- EA 7501 GICC, University of Tours, CHRU de Tours, Department of Hepato-Gastroenterology and Digestive Oncology, Tours, France
| | - Gaëlle Fromont
- N2C UMR 1069, University of Tours, INSERM, CHRU de Tours, Department of Pathology, Tours, France
| | | | - Olivier Mignen
- LBAI UMR 1227, University of Brest, INSERM, Brest, France
| | - Olivier Soriani
- iBV, INSERM, CNRS, University of the Côte d'Azur, Nice, France
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2
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Herrera F, Sevrain CM, Jaffrès PA, Couthon H, Grélard A, Dufourc EJ, Chantôme A, Potier-Cartereau M, Vandier C, Bouchet AM. Singular Interaction between an Antimetastatic Agent and the Lipid Bilayer: The Ohmline Case. ACS OMEGA 2017; 2:6361-6370. [PMID: 30023517 PMCID: PMC6045331 DOI: 10.1021/acsomega.7b00936] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/06/2017] [Accepted: 09/08/2017] [Indexed: 06/08/2023]
Abstract
SK3 channels are abnormaly expressed in metastatic cells, and Ohmline (OHM), an ether lipid, has been shown to reduce the activity of SK3 channels and the migration capacity of cancer cells. OHM incorporation into the plasma membrane is proposed to dissociate the protein complex formed between SK3 and Orai1, a potassium and a calcium channel, respectively, and would lead to a modification in the lipid environment of both the proteins. Here, we report the synthesis of deuterated OHM that affords the determination, through solid-state NMR, of its entire partitioning into membranes mimicking the SK3 environment. Use of deuterated lipids affords the demonstration of an OHM-induced membrane disordering, which is dose-dependent and increases with increasing amounts of cholesterol (CHOL). Molecular dynamics simulations comfort the disordering action and show that OHM interacts with the carbonyl and phosphate groups of stearoylphosphatidylcholine and sphingomyelin and to a minor extent with CHOL. OHM is thus proposed to remove the CHOL OH moieties away from their main binding sites, forcing a new rearrangement with other lipid groups. Such an interaction takes its origin at the lipid-water interface, but it propagates toward the entire lipid molecules and leads to a cooperative destabilization of the lipid acyl chains, that is, membrane disordering. The consequences of this reorganization of the lipid phases are discussed in the context of the OHM-induced inhibition of SK3 channels.
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Affiliation(s)
- Fernando
E. Herrera
- Physics
Department, Universidad Nacional del Litoral,
Ciudad Universitaria, 3000 Santa Fe, Argentina
| | - Charlotte M. Sevrain
- Université
de Brest, CEMCA, UMR CNRS 6521, IBSAM, 6, Avenue Victor le Gorgeu, 29238 Brest, France
- Network
and Cancer-Canceropole Grand Ouest, (IC-CGO), Maison de la Recherche
en Santé, 63 Quai
Magellan, 44000 Nantes, France
| | - Paul-Alain Jaffrès
- Université
de Brest, CEMCA, UMR CNRS 6521, IBSAM, 6, Avenue Victor le Gorgeu, 29238 Brest, France
- Network
and Cancer-Canceropole Grand Ouest, (IC-CGO), Maison de la Recherche
en Santé, 63 Quai
Magellan, 44000 Nantes, France
| | - Hélène Couthon
- Université
de Brest, CEMCA, UMR CNRS 6521, IBSAM, 6, Avenue Victor le Gorgeu, 29238 Brest, France
- Network
and Cancer-Canceropole Grand Ouest, (IC-CGO), Maison de la Recherche
en Santé, 63 Quai
Magellan, 44000 Nantes, France
| | - Axelle Grélard
- Université
Bordeaux, Institute of Chemistry & Biology of Membranes &
Nanoobjects, UMR5248 CNRS, Allée de Geoffroy St Hilaire Bât B14 Pessac, 33600 Bordeaux, France
| | - Erick J. Dufourc
- Université
Bordeaux, Institute of Chemistry & Biology of Membranes &
Nanoobjects, UMR5248 CNRS, Allée de Geoffroy St Hilaire Bât B14 Pessac, 33600 Bordeaux, France
| | - Aurélie Chantôme
- Network
and Cancer-Canceropole Grand Ouest, (IC-CGO), Maison de la Recherche
en Santé, 63 Quai
Magellan, 44000 Nantes, France
- Université
François Rabelais de Tours, Nutrition, Croissance et Cancer, Inserm UMR1069, 10 Boulevard Tonnellé Bât. Dutrochet, 2ème étage, 37032 Tours, France
| | - Marie Potier-Cartereau
- Network
and Cancer-Canceropole Grand Ouest, (IC-CGO), Maison de la Recherche
en Santé, 63 Quai
Magellan, 44000 Nantes, France
- Université
François Rabelais de Tours, Nutrition, Croissance et Cancer, Inserm UMR1069, 10 Boulevard Tonnellé Bât. Dutrochet, 2ème étage, 37032 Tours, France
| | - Christophe Vandier
- Network
and Cancer-Canceropole Grand Ouest, (IC-CGO), Maison de la Recherche
en Santé, 63 Quai
Magellan, 44000 Nantes, France
- Université
François Rabelais de Tours, Nutrition, Croissance et Cancer, Inserm UMR1069, 10 Boulevard Tonnellé Bât. Dutrochet, 2ème étage, 37032 Tours, France
| | - Ana M. Bouchet
- Network
and Cancer-Canceropole Grand Ouest, (IC-CGO), Maison de la Recherche
en Santé, 63 Quai
Magellan, 44000 Nantes, France
- Université
François Rabelais de Tours, Nutrition, Croissance et Cancer, Inserm UMR1069, 10 Boulevard Tonnellé Bât. Dutrochet, 2ème étage, 37032 Tours, France
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3
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Hassan-Zadeh E, Hussain F, Huang J. Gramicidin Peptides Alter Global Lipid Compositions and Bilayer Thicknesses of Coexisting Liquid-Ordered and Liquid-Disordered Membrane Domains. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2017; 33:3324-3332. [PMID: 28267920 DOI: 10.1021/acs.langmuir.6b03688] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Effects of adding 1 mol % of gramicidin-A on the biochemical properties of coexisting liquid-ordered and liquid-disordered (Lo + Ld) membrane domains were investigated. Quaternary giant unilamellar vesicles (GUV) of di18:1PC(DOPC)/di18:0PC(DSPC)/cholesterol/gramicidin-A were prepared using our recently developed damp-film method. The phase boundary of Lo + Ld coexisting region was determined using video fluorescence microscopy. Through fitting Nile Red fluorescence emission spectra, the thermodynamic tie-lines in the Lo + Ld two-phase region were determined. We found that at 1 mol % (i.e., ∼7% of membrane area), gramicidin peptides alter the phase boundary and thermodynamic tie-lines. Gramicidin abolishes the coexisting phases at some lipid compositions but induces phase separation at others. Previous studies of gramicidin emphasize the local perturbation of bilayer thickness adjacent to the protein through the interaction of "hydrophobic mismatch". For the first time, it becomes clear that adding gramicidin produces significant long-range and global effects on the structure of membrane domains: it alters the overall lipid compositions and bilayer thicknesses of coexisting Lo and Ld domains. We also found that gramicidin partitions favorably into the Ld phase. Adding gramicidin decreases cholesterol in the Ld phase and increases cholesterol in the Lo phase. Those compositional changes broaden the bilayer thickness difference between Lo and Ld domains and facilitate preferential partition of gramicidin into thinner Ld domains. Our results demonstrate that membrane proteins play significant roles in determining lipid compositions and bilayer thicknesses of biomembrane domains.
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Affiliation(s)
- Ebrahim Hassan-Zadeh
- Department of Physics, Mahshahr Branch, Islamic Azad University , Mahshahr, Iran
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4
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Soto-Arriaza M, Olivares-Ortega C, Lissi E. Effect of the addition of alkanols of different topology to dipalmitoyl-phosphatidylcholine vesicles in the presence of gramicidin. J Colloid Interface Sci 2012; 385:48-57. [DOI: 10.1016/j.jcis.2012.07.028] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2012] [Revised: 07/06/2012] [Accepted: 07/07/2012] [Indexed: 11/29/2022]
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5
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Kelkar DA, Chattopadhyay A. The gramicidin ion channel: A model membrane protein. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2007; 1768:2011-25. [PMID: 17572379 DOI: 10.1016/j.bbamem.2007.05.011] [Citation(s) in RCA: 264] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/10/2006] [Revised: 05/09/2007] [Accepted: 05/10/2007] [Indexed: 02/07/2023]
Abstract
The linear peptide gramicidin forms prototypical ion channels specific for monovalent cations and has been extensively used to study the organization, dynamics and function of membrane-spanning channels. In recent times, the availability of crystal structures of complex ion channels has challenged the role of gramicidin as a model membrane protein and ion channel. This review focuses on the suitability of gramicidin as a model membrane protein in general, and the information gained from gramicidin to understand lipid-protein interactions in particular. Special emphasis is given to the role and orientation of tryptophan residues in channel structure and function and recent spectroscopic approaches that have highlighted the organization and dynamics of the channel in membrane and membrane-mimetic media.
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Affiliation(s)
- Devaki A Kelkar
- Centre for Cellular and Molecular Biology, Uppal Road, Hyderabad 500 007, India
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6
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Agner G, Kaulin YA, Schagina LV, Takemoto JY, Blasko K. Effect of temperature on the formation and inactivation of syringomycin E pores in human red blood cells and bimolecular lipid membranes. BIOCHIMICA ET BIOPHYSICA ACTA 2000; 1466:79-86. [PMID: 10825433 DOI: 10.1016/s0005-2736(00)00173-5] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
The effects of temperature on the formation and inactivation of syringomycin E (SRE) pores were investigated with human red blood cells (RBCs) and lipid bilayer membranes (BLMs). SRE enhanced the RBC membrane permeability of 86Rb and monomeric hemoglobin in a temperature dependent manner. The kinetics of 86Rb and hemoglobin effluxes were measured at different temperatures and pore formation was found to be only slightly affected, while inactivation was strongly influenced by temperature. At 37 degrees C, SRE pore inactivation began 15 min after and at 20 degrees C, 40 min after SRE addition. At 6 degrees C, below the phase transition temperature of the major lipid components of the RBC membrane, no inactivation occurred for as long as 90 min. With BLMs, SRE induced a large current that remained stable at 14 degrees C, but at 23 degrees C it decreased over time while the single channel conductance and dwell time did not change. The results show that the temperature dependent inactivation of SRE pores is due to a decrease in the number of open pores.
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Affiliation(s)
- G Agner
- Institute of Biophysics and Radiation Biology, Semmelweis University of Medicine, Bupapest VIII, Budapest, Hungary
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7
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Salom D, Pérez-Payá E, Pascal J, Abad C. Environment- and sequence-dependent modulation of the double-stranded to single-stranded conformational transition of gramicidin A in membranes. Biochemistry 1998; 37:14279-91. [PMID: 9760266 DOI: 10.1021/bi980733k] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The role of the membrane lipid composition and the individual Trp residues in the conformational rearrangement of gramicidin A along the folding pathway to its channel conformation has been examined in phospholipid bilayers by means of previously described size-exclusion high-performance liquid chromatography HPLC-based strategy (Bañó et al. (1991) Biochemistry 30, 886). It has been demonstrated that the chemical composition of the membrane influences the transition rate of the peptide rearrangement from double-stranded dimers to beta-helical monomers. The chemical modification of Trp residues, or its substitution by the more hydrophobic residues phenylalanine or naphthylalanine, stabilized the double-stranded dimer conformation in model membranes. This effect was more notable as the number of Trp-substituted residues increased (tetra > tri > di > mono), and it was also influenced by the specific position of the substituted amino acid residue in the sequence, in the order Trp-9 approximately Trp-13 > Trp-11 > Trp-15. Moreover, it was verified that nearly a full contingent of indoles (Trp-13, -11, and -9) is necessary to induce a quantitative conversion from double-stranded dimers to single-stranded monomers, although Trp-9 and Trp-13 seemed to be key residues for the stabilization of the beta-helical monomeric conformation of gramicidin A. The conformation adopted for monomeric Trp --> Phe substitution analogues in lipid vesicles resulted in CD spectra similar to the typical single-stranded beta6.3-helical conformation of gramicidin A. However, the Trp --> Phe substitution analogues showed decreased antibiotic activity as the number of Trp decreased.
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Affiliation(s)
- D Salom
- Departament de Bioquímica i Biologia Molecular, Universitat de València, Burjassot, Spain
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8
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Blasko K, Schagina LV, Agner G, Kaulin YA, Takemoto JY. Membrane sterol composition modulates the pore forming activity of syringomycin E in human red blood cells. BIOCHIMICA ET BIOPHYSICA ACTA 1998; 1373:163-9. [PMID: 9733959 DOI: 10.1016/s0005-2736(98)00101-1] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
The effect of lipopeptide antifungal agent, syringomycin E (SRE) on the membrane permeability of human red blood cells (RBCs) was studied. SRE added to RBCs above a concentration of 2x106 molecules/cell (50 microgram/ml RBCs) caused a rapid and concentration dependent lysis of a small subpopulation of RBCs; the extent of this lysis remained unchanged as long as 100 min. During this time period the membranes of the unlysed cells had enhanced permeability for ions which was monitored by direct measurement of 86Rb flux. Both the extent of cell lysis and ion transport rate showed linear relationships with SRE concentration demonstrating a random distribution of SRE molecules in red blood cells. The kinetics of the 86Rb efflux suggested pore formation by syringomycin E. The pores had discrete life times and were eventually inactivated. The pores were also a pathway for efflux of monomeric haemoglobin. Alteration of the membrane sterol composition, i.e. depletion of cholesterol by 50% or partial ergosterol substitution of the cholesterol increased the SRE induced membrane permeability for 86Rb by two orders compared to membranes with unaltered sterol composition. This modification of the sterol composition promotes the pore forming activity of this lipopeptide in the membrane.
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Affiliation(s)
- K Blasko
- Institute of Biophysics, Semmelweis University of Medicine, POB 263, 1444 Budapest, Hungary.
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9
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Kolf-Clauw M, Chevy F, Siliart B, Wolf C, Mulliez N, Roux C. Cholesterol biosynthesis inhibited by BM15.766 induces holoprosencephaly in the rat. TERATOLOGY 1997; 56:188-200. [PMID: 9358606 DOI: 10.1002/(sici)1096-9926(199709)56:3<188::aid-tera2>3.0.co;2-y] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
To confirm that blocking 7-dehydrocholesterol delta 7 reductase (7DHC reductase), as observed in Smith-Lemli-Opitz syndrome (SLOS), induces craniofacial defects, we tested BM15.766, which blocks 7DHC reductase but is chemically unrelated to the holoprosencephaly-inducing teratogen AY9944. Rats were given BM15.766 either in methylcellulose from days (D) 1 through D11 (3 treated groups: protocol A) or in olive oil from D4 through D7 (300 mg/kg/d: protocol B). The sera were sampled on D0, D3, and D5 or D6, D10, D14, and D21 to measure cholesterol and dehydrocholesterols in all groups and steroid hormones in protocol B. D21 fetuses showed the holoprosencephaly spectrum of malformations and the treated dams low cholesterol and accumulation of 7DHC, 8DHC, and trienols, as in SLOS-affected children. In the 3 dosage groups the malformations were dose-related and enzymatic cholesterol decreased to a plateau. The DHC reached 25-44% of the total sterols in the dams. In protocol B, one-third of the BM15.766-treated fetuses presented facial malformations and almost two-thirds pituitary agenesis. On D10, cholesterol reached a minimum and the DHC a maximum while estradiol 17 beta and progesterone were lowered, the latter decreasing in correlation with cholesterolemia. A sterol profile similar to that previously observed after AY9944 associated with a similarly high incidence of pituitary agenesis confirmed that time-limited inhibition of 7DHC reductase induces holoprosencephaly and that pituitary agenesis is the minor form of holoprosencephaly.
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Affiliation(s)
- M Kolf-Clauw
- Toxicology Department, Ecole Nationale Vétérinaire d'Alfort, Maisons-Alfort, France
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10
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Feigin AM, Schagina LV, Takemoto JY, Teeter JH, Brand JG. The effect of sterols on the sensitivity of membranes to the channel-forming antifungal antibiotic, syringomycin E. BIOCHIMICA ET BIOPHYSICA ACTA 1997; 1324:102-10. [PMID: 9059503 DOI: 10.1016/s0005-2736(96)00214-3] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
The ability of three sterols of different structure to influence the interaction of syringomycin E (an antifungal antibiotic that forms voltage dependent channels in planar lipid bilayers) with a planar lipid bilayer was evaluated. The rate of increase of bilayer conductance induced by syringomycin E was about 1000-times less in bilayers containing 50 mol% of cholesterol compared to bilayers without sterols. The effect of ergosterol (the primary sterol of fungal cells) on the sensitivity of bilayers to syringomycin E was much weaker than that of cholesterol, while stigmasterol (one of the main sterols of plant cells) did not significantly influence the ability of syringomycin E to induce a conductance increase in the bilayer. None of the sterols altered the single channel conductance properties of syringomycin E. These observations suggest that cholesterol affects the sensitivity of target membranes to syringomycin E by enlarging the energy barrier for channel formation rather than participating in channel formation itself.
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Affiliation(s)
- A M Feigin
- Monell Chemical Senses Center, Philadelphia, PA 19104-3308, USA.
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11
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Tint GS, Batta AK, Xu G, Shefer S, Honda A, Irons M, Elias ER, Salen G. The Smith-Lemli-Opitz syndrome: a potentially fatal birth defect caused by a block in the last enzymatic step in cholesterol biosynthesis. Subcell Biochem 1997; 28:117-44. [PMID: 9090293 DOI: 10.1007/978-1-4615-5901-6_5] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Affiliation(s)
- G S Tint
- Research Service, Department of Veterans Affairs Medical Center, East Orange, New Jersey 07019, USA
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12
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Otten-Kuipers MA, Beumer TL, Kronenburg NA, Roelofsen B, Op den Kamp JA. Effects of gramicidin and tryptophan-N-formylated gramicidin on the sodium and potassium content of human erythrocytes. Mol Membr Biol 1996; 13:225-32. [PMID: 9116761 DOI: 10.3109/09687689609160600] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
In order to get a better understanding in the mechanism by which tryptophan-N-formylated gramicidin (NFG) and gramicidin kill the malaria parasite Plasmodium falciparum in vitro, we studied the capacity of these peptides to change the potassium, as well as the sodium, composition of normal human erythrocytes, and their ability to cause cell lysis. It is shown that both peptides are able to induce potassium leakage from, and sodium flux into, erythrocytes in such a manner that it is most likely that they are able to form cation channels in the membrane of these cells. For both peptides, potassium efflux proceeds at a faster rate than sodium influx, but this difference is greater for NFG than for gramicidin. This explains the observation that gramicidin is more lytic than NFG is, even when comparing concentrations that show the same antimalarial activity. The finding that gramicidin is approximately 10 times more active than NFG in causing potassium efflux from normal erythrocytes, as well as in killing the malaria parasite, supports the hypothesis that peptide-induced parasite death is related to their capacity to induce potassium leakage from infected erythrocytes. Finally, the observation that erythrocytes are able to restore their normal ion contents after losing more than 50% of their potassium content by incubation with NFG or gramicidin, suggests that, in vivo, and upon treatment with drug concentrations that cause full inhibition of parasite growth, these cells would not be irreversibly damaged by action of the drugs.
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Affiliation(s)
- M A Otten-Kuipers
- Department of Lipid Biochemistry, Centre for Biomembranes and Lipid Enzymology, Institute of Biomembranes, Utrecht University, The Netherlands
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13
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Kolf-Clauw M, Chevy F, Wolf C, Siliart B, Citadelle D, Roux C. Inhibition of 7-dehydrocholesterol reductase by the teratogen AY9944: a rat model for Smith-Lemli-Opitz syndrome. TERATOLOGY 1996; 54:115-25. [PMID: 8987154 DOI: 10.1002/(sici)1096-9926(199609)54:3<115::aid-tera1>3.0.co;2-2] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Our aim is to verify the validity of a rat model proposed for Smith-Lemli-Opitz (SLO) syndrome, a developmental disorder characterized by a defect in 7-dehydrocholesterol-delta 7 (7DHC)-reductase and by facial dysmorphism close to the holoprosencephaly caused by the teratogen AY9944. We investigated the sterol profile in rats treated with AY9944 blocking 7DHC-reductase. AY9944 was given orally to rats on gestation day 3 (D3). The sera were sampled for kinetic data on D3, D6, D9, D12, and D21. Cholesterol was measured in parallel by the routine enzymatic method and by the gas chromatography/mass spectrometry (GC-MS) procedure used in SLO diagnosis. In addition to sterols, we dosed steroid hormones punctually on D4 and on D10, and examined D21 fetuses in other animals. The enzymatic method was not specific for cholesterol, and measured 70% pure 7DHC added to a normal serum. On D21, 77% live fetuses showed pituitary agenesis. Cholesterol was rapidly reduced by more than 50% on D6 involving an accumulation of 7DHC, 8DHC, and trienols, as identified in SLO-affected children. The most abundant 7DHC reached a maximum from D9 to D12, equaling cholesterol on D9 (11 mg/dl). On D10, the magnitudes of hypocholesterolemic and of 7DHC accumulation were found to be dose-dependent. Progesterone was reduced as early as 24 hr after treatment and dropped to 40% of the levels in the controls on D10, correlating to the decrease in cholesterolemia. This rat model reproduces the same biochemical perturbations as seen in SLO, strongly suggesting that aberrant sterols (7DHC, 8DHC, or nortrienol) may contribute to the developmental defects.
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Affiliation(s)
- M Kolf-Clauw
- Toxicology Department, Ecole Nationale Vétérinaire d'Alfort, Maisons-Alfort, France
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14
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Waldeck AR, Nouri-Sorkhabi MH, Sullivan DR, Kuchel PW. Effects of cholesterol on transmembrane water diffusion in human erythrocytes measured using pulsed field gradient NMR. Biophys Chem 1995; 55:197-208. [PMID: 7626740 DOI: 10.1016/0301-4622(95)00007-k] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
The effect of cholesterol on the diffusional permeability of water in suspensions of human erythrocytes was studied by means of pulsed field gradient NMR, which unlike the relaxation NMR method avoids the use of Mn2+ ions. The analysis allows the internal and external diffusion coefficients, as well as the lifetime characterizing the rate of exchange between the two regions, to be extracted from the data. The cholesterol content of the erythrocyte membranes was altered by incubating the cells with sonicated dispersions of cholesterol/dipalmitoyl phosphatidylcholine at 310 K. It was shown that decreasing the molar ratio of cholesterol to phospholipid (C/P ratio) of the membrane, from a mean value of 0.92 for normal cells (controls) to a value of 0.46, had little effect on the intracellular mean residence lifetime and the diffusional permeability. Enriching the cholesterol content of the membrane, however, had a marked effect on the exchange lifetime and the diffusional permeability. At a C/P ratio of approximately 1.5 the rate of transport was reduced approximately 3.5-fold. A further increase of the cholesterol content, to a C/P ratio of approximately 1.9, resulted in an enhancement of the rate of transport back to a normal (control) value, which was characterized by a lifetime of 8-9 ms. The combined inhibition of the water permeability by cholesterol and pCMBS for cells with C/P ratios of 1.44 and 1.54, and by pCMBS alone for cells with a control C/P ratio resulted in the same value for Pd within experimental error.
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Affiliation(s)
- A R Waldeck
- Department of Biochemistry, University of Sydney, N.S.W., Australia
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