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Van Lommel J, Holtof M, Tilleman L, Cools D, Vansteenkiste S, Polgun D, Verdonck R, Van Nieuwerburgh F, Vanden Broeck J. Post-feeding transcriptomics reveals essential genes expressed in the midgut of the desert locust. Front Physiol 2023; 14:1232545. [PMID: 37692997 PMCID: PMC10484617 DOI: 10.3389/fphys.2023.1232545] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2023] [Accepted: 07/26/2023] [Indexed: 09/12/2023] Open
Abstract
The digestive tract constitutes an important interface between an animal's internal and external environment. In insects, available gut transcriptome studies are mostly exploratory or look at changes upon infection or upon exposure to xenobiotics, mainly performed in species belonging to holometabolan orders, such as Diptera, Lepidoptera or Coleoptera. By contrast, studies focusing on gene expression changes after food uptake and during digestion are underrepresented. We have therefore compared the gene expression profiles in the midgut of the desert locust, Schistocerca gregaria, between three different time points after feeding, i.e., 24 h (no active digestion), 10 min (the initial stage of feeding), and 2 h (active food digestion). The observed gene expression profiles were consistent with the polyphagous herbivorous lifestyle of this hemimetabolan (orthopteran) species. Our study reveals the upregulation of 576 genes 2 h post-feeding. These are mostly predicted to be associated with digestive physiology, such as genes encoding putative digestive enzymes or nutrient transporters, as well as genes putatively involved in immunity or in xenobiotic metabolism. The 10 min time point represented an intermediate condition, suggesting that the S. gregaria midgut can react rapidly at the transcriptional level to the presence of food. Additionally, our study demonstrated the critical importance of two transcripts that exhibited a significant upregulation 2 h post-feeding: the vacuolar-type H(+)-ATPase and the sterol transporter Niemann-Pick 1b protein, which upon RNAi-induced knockdown resulted in a marked increase in mortality. Their vital role and accessibility via the midgut lumen may make the encoded proteins promising insecticidal target candidates, considering that the desert locust is infamous for its huge migrating swarms that can devastate the agricultural production in large areas of Northern Africa, the Middle East, and South Asia. In conclusion, the transcriptome datasets presented here will provide a useful and promising resource for studying the midgut physiology of S. gregaria, a socio-economically important pest species.
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Affiliation(s)
- Joachim Van Lommel
- Molecular Developmental Physiology and Signal Transduction Lab, Department of Biology, University of Leuven, Leuven, Belgium
| | - Michiel Holtof
- Molecular Developmental Physiology and Signal Transduction Lab, Department of Biology, University of Leuven, Leuven, Belgium
| | | | - Dorien Cools
- Molecular Developmental Physiology and Signal Transduction Lab, Department of Biology, University of Leuven, Leuven, Belgium
| | - Seppe Vansteenkiste
- Molecular Developmental Physiology and Signal Transduction Lab, Department of Biology, University of Leuven, Leuven, Belgium
| | - Daria Polgun
- Molecular Developmental Physiology and Signal Transduction Lab, Department of Biology, University of Leuven, Leuven, Belgium
| | - Rik Verdonck
- Molecular Developmental Physiology and Signal Transduction Lab, Department of Biology, University of Leuven, Leuven, Belgium
- Environmental Biology, Centre for Environmental Sciences, Hasselt University, Hasselt, Belgium
| | | | - Jozef Vanden Broeck
- Molecular Developmental Physiology and Signal Transduction Lab, Department of Biology, University of Leuven, Leuven, Belgium
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Coyan FC, Abderemane-Ali F, Amarouch MY, Piron J, Mordel J, Nicolas CS, Steenman M, Mérot J, Marionneau C, Thomas A, Brasseur R, Baró I, Loussouarn G. A long QT mutation substitutes cholesterol for phosphatidylinositol-4,5-bisphosphate in KCNQ1 channel regulation. PLoS One 2014; 9:e93255. [PMID: 24681627 PMCID: PMC3969324 DOI: 10.1371/journal.pone.0093255] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2013] [Accepted: 03/03/2014] [Indexed: 01/08/2023] Open
Abstract
Introduction Phosphatidylinositol-4,5-bisphosphate (PIP2) is a cofactor necessary for the activity of KCNQ1 channels. Some Long QT mutations of KCNQ1, including R243H, R539W and R555C have been shown to decrease KCNQ1 interaction with PIP2. A previous study suggested that R539W is paradoxically less sensitive to intracellular magnesium inhibition than the WT channel, despite a decreased interaction with PIP2. In the present study, we confirm this peculiar behavior of R539W and suggest a molecular mechanism underlying it. Methods and Results COS-7 cells were transfected with WT or mutated KCNE1-KCNQ1 channel, and patch-clamp recordings were performed in giant-patch, permeabilized-patch or ruptured-patch configuration. Similar to other channels with a decreased PIP2 affinity, we observed that the R243H and R555C mutations lead to an accelerated current rundown when membrane PIP2 levels are decreasing. As opposed to R243H and R555C mutants, R539W is not more but rather less sensitive to PIP2 decrease than the WT channel. A molecular model of a fragment of the KCNQ1 C-terminus and the membrane bilayer suggested that a potential novel interaction of R539W with cholesterol stabilizes the channel opening and hence prevents rundown upon PIP2 depletion. We then carried out the same rundown experiments under cholesterol depletion and observed an accelerated R539W rundown that is consistent with this model. Conclusions We show for the first time that a mutation may shift the channel interaction with PIP2 to a preference for cholesterol. This de novo interaction wanes the sensitivity to PIP2 variations, showing that a mutated channel with a decreased affinity to PIP2 could paradoxically present a slowed current rundown compared to the WT channel. This suggests that caution is required when using measurements of current rundown as an indicator to compare WT and mutant channel PIP2 sensitivity.
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Affiliation(s)
- Fabien C. Coyan
- l'institut du thorax, Institut National de la Santé et de la Recherche Médicale, Nantes, France
- Unité Mixte de Recherche 6291, Centre National de la Recherche Scientifique, Nantes, France
- Unité de Formation et de Recherche de Médecine, Université de Nantes, Nantes, France
| | - Fayal Abderemane-Ali
- l'institut du thorax, Institut National de la Santé et de la Recherche Médicale, Nantes, France
- Unité Mixte de Recherche 6291, Centre National de la Recherche Scientifique, Nantes, France
- Unité de Formation et de Recherche de Médecine, Université de Nantes, Nantes, France
| | - Mohamed Yassine Amarouch
- l'institut du thorax, Institut National de la Santé et de la Recherche Médicale, Nantes, France
- Unité Mixte de Recherche 6291, Centre National de la Recherche Scientifique, Nantes, France
- Unité de Formation et de Recherche de Médecine, Université de Nantes, Nantes, France
| | - Julien Piron
- l'institut du thorax, Institut National de la Santé et de la Recherche Médicale, Nantes, France
- Unité Mixte de Recherche 6291, Centre National de la Recherche Scientifique, Nantes, France
- Unité de Formation et de Recherche de Médecine, Université de Nantes, Nantes, France
| | - Jérôme Mordel
- l'institut du thorax, Institut National de la Santé et de la Recherche Médicale, Nantes, France
- Unité Mixte de Recherche 6291, Centre National de la Recherche Scientifique, Nantes, France
- Unité de Formation et de Recherche de Médecine, Université de Nantes, Nantes, France
| | - Céline S. Nicolas
- l'institut du thorax, Institut National de la Santé et de la Recherche Médicale, Nantes, France
- Unité Mixte de Recherche 6291, Centre National de la Recherche Scientifique, Nantes, France
- Unité de Formation et de Recherche de Médecine, Université de Nantes, Nantes, France
| | - Marja Steenman
- l'institut du thorax, Institut National de la Santé et de la Recherche Médicale, Nantes, France
- Unité Mixte de Recherche 6291, Centre National de la Recherche Scientifique, Nantes, France
| | - Jean Mérot
- l'institut du thorax, Institut National de la Santé et de la Recherche Médicale, Nantes, France
- Unité Mixte de Recherche 6291, Centre National de la Recherche Scientifique, Nantes, France
- Unité de Formation et de Recherche de Médecine, Université de Nantes, Nantes, France
| | - Céline Marionneau
- l'institut du thorax, Institut National de la Santé et de la Recherche Médicale, Nantes, France
- Unité Mixte de Recherche 6291, Centre National de la Recherche Scientifique, Nantes, France
- Unité de Formation et de Recherche de Médecine, Université de Nantes, Nantes, France
| | - Annick Thomas
- Institut de Pharmacologie et de Biologie Structurale, Centre National de la Recherche Scientifique, Toulouse, France
| | - Robert Brasseur
- Centre de Biophysique Moléculaire Numérique, University of Liège, Gembloux, Belgium
| | - Isabelle Baró
- l'institut du thorax, Institut National de la Santé et de la Recherche Médicale, Nantes, France
- Unité Mixte de Recherche 6291, Centre National de la Recherche Scientifique, Nantes, France
- Unité de Formation et de Recherche de Médecine, Université de Nantes, Nantes, France
| | - Gildas Loussouarn
- l'institut du thorax, Institut National de la Santé et de la Recherche Médicale, Nantes, France
- Unité Mixte de Recherche 6291, Centre National de la Recherche Scientifique, Nantes, France
- Unité de Formation et de Recherche de Médecine, Université de Nantes, Nantes, France
- * E-mail:
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Caragata EP, Rancès E, O'Neill SL, McGraw EA. Competition for amino acids between Wolbachia and the mosquito host, Aedes aegypti. MICROBIAL ECOLOGY 2014; 67:205-218. [PMID: 24337107 DOI: 10.1007/s00248-013-0339-4] [Citation(s) in RCA: 110] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/02/2013] [Accepted: 11/28/2013] [Indexed: 06/03/2023]
Abstract
The endosymbiont Wolbachia represents a promising method of dengue control, as it reduces the ability of the primary vector, the mosquito Aedes aegypti, to transmit viruses. When mosquitoes infected with the virulent Wolbachia strain wMelPop are fed non-human blood, there is a drastic reduction in mosquito fecundity and egg viability. Wolbachia has a reduced genome and is clearly dependent on its host for a wide range of nutritional needs. The fitness defects seen in wMelPop-infected A. aegypti could be explained by competition between the mosquito and the symbiont for essential blood meal nutrients, the profiles of which are suboptimal in non-human blood. Here, we examine cholesterol and amino acids as candidate molecules for competition, as they have critical roles in egg structural development and are known to vary between blood sources. We found that Wolbachia infection reduces total cholesterol levels in mosquitoes by 15-25%. We then showed that cholesterol supplementation of a rat blood meal did not improve fecundity or egg viability deficits. Conversely, amino acid supplementation of sucrose before and after a sheep blood meal led to statistically significant increases in fecundity of approximately 15-20 eggs per female and egg viability of 30-40%. This mosquito system provides the first empirical evidence of competition between Wolbachia and a host over amino acids and may suggest a general feature of Wolbachia-insect associations. These competitive processes could affect many aspects of host physiology and potentially mosquito fitness, a key concern for Wolbachia-based mosquito biocontrol.
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Affiliation(s)
- Eric P Caragata
- School of Biological Sciences, Monash University, Melbourne, VIC, Australia, 3800
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Ormerod KG, Rogasevskaia TP, Coorssen JR, Mercier AJ. Cholesterol-independent effects of methyl-β-cyclodextrin on chemical synapses. PLoS One 2012; 7:e36395. [PMID: 22590538 PMCID: PMC3348160 DOI: 10.1371/journal.pone.0036395] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2011] [Accepted: 04/05/2012] [Indexed: 01/22/2023] Open
Abstract
The cholesterol chelating agent, methyl-β-cyclodextrin (MβCD), alters synaptic function in many systems. At crayfish neuromuscular junctions, MβCD is reported to reduce excitatory junctional potentials (EJPs) by impairing impulse propagation to synaptic terminals, and to have no postsynaptic effects. We examined the degree to which physiological effects of MβCD correlate with its ability to reduce cholesterol, and used thermal acclimatization as an alternative method to modify cholesterol levels. MβCD impaired impulse propagation and decreased EJP amplitude by 40% (P<0.05) in preparations from crayfish acclimatized to 14 °C but not from those acclimatized to 21 °C. The reduction in EJP amplitude in the cold-acclimatized group was associated with a 49% reduction in quantal content (P<0.05). MβCD had no effect on input resistance in muscle fibers but decreased sensitivity to the neurotransmitter L-glutamate in both warm- and cold-acclimatized groups. This effect was less pronounced and reversible in the warm-acclimatized group (90% reduction in cold, P<0.05; 50% reduction in warm, P<0.05). MβCD reduced cholesterol in isolated nerve and muscle from cold- and warm-acclimatized groups by comparable amounts (nerve: 29% cold, 25% warm; muscle: 20% cold, 18% warm; P<0.05). This effect was reversed by cholesterol loading, but only in the warm-acclimatized group. Thus, effects of MβCD on glutamate-sensitivity correlated with its ability to reduce cholesterol, but effects on impulse propagation and resulting EJP amplitude did not. Our results indicate that MβCD can affect both presynaptic and postsynaptic properties, and that some effects of MβCD are unrelated to cholesterol chelation.
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Affiliation(s)
- Kiel G. Ormerod
- Department of Biological Sciences, Brock University, St. Catharines, Ontario, Canada
| | - Tatiana P. Rogasevskaia
- Department of Physiology and Biophysics, Faculty of Medicine, University of Calgary, Calgary, Alberta, Canada
| | - Jens R. Coorssen
- Department of Molecular Physiology, School of Medicine and the Molecular Medicine Research Group, University of Western Sydney, Penrith South DC, New South Wales, Australia
| | - A. Joffre Mercier
- Department of Biological Sciences, Brock University, St. Catharines, Ontario, Canada
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Drosophila QVR/SSS modulates the activation and C-type inactivation kinetics of Shaker K(+) channels. J Neurosci 2011; 31:11387-95. [PMID: 21813698 DOI: 10.1523/jneurosci.0502-11.2011] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
The quiver/sleepless (qvr/sss) gene encodes a small, glycosylphosphatidylinositol-anchored protein that plays a critical role in the regulation of sleep in Drosophila. Loss-of-function mutations in qvr/sss severely suppress sleep and effect multiple changes in in situ Shaker K(+) currents, including decreased magnitude, slower time-to-peak, and cumulative inactivation. Recently, we demonstrated that SLEEPLESS (SSS) protein modulates Shaker channel activity, possibly through a direct interaction at the plasma membrane. We show here that SSS accelerates the activation of heterologously expressed Shaker channels with no effect on deactivation or fast N-type inactivation. Furthermore, this SSS-induced acceleration is sensitive to the pharmacological disruption of lipid rafts and sufficiently accounts for the slower time-to-peak of in situ Shaker currents seen in qvr/sss mutants. We also find that SSS decreases the rate of C-type inactivation of heterologously expressed Shaker channels, providing a potential mechanism for the cumulative inactivation phenotype induced by qvr/sss loss-of-function mutations. Kinetic modeling based on the in vitro results suggests that the SSS-dependent regulation of channel kinetics accounts for nearly 40% of the decrease in Shaker current magnitude in flies lacking SSS. Sleep duration in qvr/sss-null mutants is restored to normal by a qvr/sss transgene that fully rescues the Shaker kinetic phenotypes but only partially rescues the decrease in current magnitude. Together, these results suggest that the role of SSS in the regulation of sleep in Drosophila correlates more strongly with the effects of SSS on Shaker kinetics than current magnitude.
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Abstract
The last 10 years have seen a rebirth of interest in lipid biology in the fields of Drosophila development and neurobiology, and sphingolipids have emerged as controlling many processes that have not previously been studied from the viewpoint of lipid biochemistry. Mutations in sphingolipid regulatory enzymes have been pinpointed as affecting cell survival and growth in tissues ranging from muscle to retina. Specification of cell types are also influenced by sphingolipid regulatory pathways, as genetic interactions of glycosphingolipid biosynthetic enzymes with many well-known signaling receptors such as Notch and epidermal growth factor receptor reveal. Furthermore, studies in flies are now uncovering unexpected roles of sphingolipids in controlling lipid storage and response to nutrient availability. The sophisticated genetics of Drosophila is particularly well suited to uncover the roles of sphingolipid regulatory enzymes in development and metabolism, especially in light of conserved pathways that are present in both flies and mammals. The challenges that remain in the field of sphingolipid biology in Drosophila are to combine traditional developmental genetics with more analytical biochemical and biophysical methods, to quantify and localize the responses of these lipids to genetic and metabolic perturbations.
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Affiliation(s)
- Rachel Kraut
- School of Biological Sciences, Nanyang Technological University, Singapore, Singapore.
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Abstract
Synaptic vesicles have a high sterol content, but the importance of vesicular sterols during vesicle recycling is unclear. We used the Drosophila temperature-sensitive dynamin mutant, shibire-ts1, to block endocytosis of recycling synaptic vesicles and to trap them reversibly at the plasma membrane where they were accessible to sterol extraction. Depletion of sterols from trapped vesicles prevented recovery of synaptic transmission after removal of the endocytic block. Measurement of vesicle recycling with synaptopHluorin, FM1-43, and FM4-64 demonstrated impaired membrane retrieval after vesicular sterol depletion. When plasma membrane sterols were extracted before vesicle trapping, no vesicle recycling defects were observed. Ultrastructural analysis indicated accumulation of endosomes and a defect in the formation of synaptic vesicles in synaptic terminals subjected to vesicular sterol depletion. Our results demonstrate the importance of a high vesicular sterol concentration for endocytosis and suggest that vesicular and membrane sterol pools do not readily intermingle during vesicle recycling.
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Abstract
A variety of ion channels, including members of all major ion channel families, have been shown to be regulated by changes in the level of membrane cholesterol and partition into cholesterol-rich membrane domains. In general, several types of cholesterol effects have been described. The most common effect is suppression of channel activity by an increase in membrane cholesterol, an effect that was described for several types of inwardly-rectifying K(+) channels, voltage-gated K(+) channels, Ca(+2) sensitive K(+) channels, voltage-gated Na(+) channels, N-type voltage-gated Ca(+2) channels and volume-regulated anion channels. In contrast, several types of ion channels, such as epithelial amiloride-sensitive Na(+) channels and Transient Receptor Potential channels, as well as some of the types of inwardly-rectifying and voltage-gated K(+) channels were shown to be inhibited by cholesterol depletion. Cholesterol was also shown to alter the kinetic properties and current-voltage dependence of several voltage-gated channels. Finally, maintaining membrane cholesterol level is required for coupling ion channels to signalling cascades. In terms of the mechanisms, three general mechanisms have been proposed: (i) specific interactions between cholesterol and the channel protein, (ii) changes in the physical properties of the membrane bilayer and (iii) maintaining the scaffolds for protein-protein interactions. The goal of this review is to describe systematically the role of cholesterol in regulation of the major types of ion channels and to discuss these effects in the context of the models proposed.
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Affiliation(s)
- Irena Levitan
- Department of Medicine, University of Illinois at Chicago, Chicago, IL, USA.
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Guo J, Chi S, Xu H, Jin G, Qi Z. Effects of cholesterol levels on the excitability of rat hippocampal neurons. Mol Membr Biol 2009; 25:216-23. [DOI: 10.1080/09687680701805541] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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Neuronal loss of Drosophila NPC1a causes cholesterol aggregation and age-progressive neurodegeneration. J Neurosci 2008; 28:6569-82. [PMID: 18579730 DOI: 10.1523/jneurosci.5529-07.2008] [Citation(s) in RCA: 77] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
The mistrafficking and consequent cytoplasmic accumulation of cholesterol and sphingolipids is linked to multiple neurodegenerative diseases. One class of disease, the sphingolipid storage diseases, includes Niemann-Pick disease type C (NPC), caused predominantly (95%) by mutation of the NPC1 gene. A disease model has been established through mutation of Drosophila NPC1a (dnpc1a). Null mutants display early lethality attributable to loss of cholesterol-dependent ecdysone steroid hormone production. Null mutants rescued to adults by restoring ecdysone production mimic human NPC patients with progressive motor defects and reduced life spans. Analysis of dnpc1a null brains shows elevated overall cholesterol levels and progressive accumulation of filipin-positive cholesterol aggregates within brain and retina, as well as isolated cultured brain neurons. Ultrastructural imaging of dnpc1a mutant brains reveals age-progressive accumulation of striking multilamellar and multivesicular organelles, preceding the onset of neurodegeneration. Consistently, electroretinogram recordings show age-progressive loss of phototransduction and photoreceptor synaptic transmission. Early lethality, movement impairments, neuronal cholesterol deposits, accumulation of multilamellar bodies, and age-dependent neurodegeneration are all rescued by targeted neuronal expression of a wild-type dnpc1a transgene. Interestingly, targeted expression of dnpc1a in glia also provides limited rescue of adult lethality. Generation of dnpc1a null mutant neuron clones in the brain reveals cell-autonomous requirements for dNPC1a in cholesterol and membrane trafficking. These data demonstrate a requirement for dNPC1a in the maintenance of neuronal function and viability and show that loss of dNPC1a in neurons mimics the human neurodegenerative condition.
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Abi-Char J, Maguy A, Coulombe A, Balse E, Ratajczak P, Samuel JL, Nattel S, Hatem SN. Membrane cholesterol modulates Kv1.5 potassium channel distribution and function in rat cardiomyocytes. J Physiol 2007; 582:1205-17. [PMID: 17525113 PMCID: PMC2075263 DOI: 10.1113/jphysiol.2007.134809] [Citation(s) in RCA: 75] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Membrane lipid composition is a major determinant of cell excitability. In this study, we assessed the role of membrane cholesterol composition in the distribution and function of Kv1.5-based channels in rat cardiac membranes. In isolated rat atrial myocytes, the application of methyl-beta-cyclodextrin (MCD), an agent that depletes membrane cholesterol, caused a delayed increase in the Kv1.5-based sustained component, I(kur), which reached steady state in approximately 7 min. This effect was prevented by preloading the MCD with cholesterol. MCD-increased current was inhibited by low 4-aminopyridine concentration. Neonatal rat cardiomyocytes transfected with Green Fluorescent Protein (GFP)-tagged Kv1.5 channels showed a large ultrarapid delayed-rectifier current (I(Kur)), which was also stimulated by MCD. In atrial cryosections, Kv1.5 channels were mainly located at the intercalated disc, whereas caveolin-3 predominated at the cell periphery. A small portion of Kv1.5 floated in the low-density fractions of step sucrose-gradient preparations. In live neonatal cardiomyocytes, GFP-tagged Kv1.5 channels were predominantly organized in clusters at the basal plasma membrane. MCD caused reorganization of Kv1.5 subunits into larger clusters that redistributed throughout the plasma membrane. The MCD effect on clusters was sizable 7 min after its application. We conclude that Kv1.5 subunits are concentrated in cholesterol-enriched membrane microdomains distinct from caveolae, and that redistribution of Kv1.5 subunits by depletion of membrane cholesterol increases their current-carrying capacity.
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