Genome-wide chromatin immunoprecipitation sequencing (ChIP-seq) in a monoclonal population of HEK-293 cells stably expressing a Tet-OFF regulatory system (i.e. HEK293-PFL-TFEB).
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ABSTRACT:
ORGANISM(S): Homo sapiens
PROVIDER: GSE98246 | GEO | 2020/09/28
REPOSITORIES: GEO
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Project description:Cholesterol is one of the major lipid components of the plasma membrane in mammalian cells and is involved in the regulation of a number of ion channels. The present study investigates how large conductance Ca(2+)-activated K(+) (BK) channels are regulated by membrane cholesterol in BK-HEK 293 cells expressing both the ?-subunit hKCa1.1 and the auxiliary ?1-subunit or in hKCa1.1-HEK 293 cells expressing only the ?-subunit hKCa1.1 using approaches of electrophysiology, molecular biology, and immunocytochemistry. Membrane cholesterol was depleted in these cells with methyl-?-cyclodextrin (M?CD), and enriched with cholesterol-saturated M?CD (M?CD-cholesterol) or low-density lipoprotein (LDL). We found that BK current density was decreased by cholesterol enrichment in BK-HEK 293 cells, with a reduced expression of KCa1.1 protein, but not the ?1-subunit protein. This effect was fully countered by the proteasome inhibitor lactacystin or the lysosome function inhibitor bafilomycin A1. Interestingly, in hKCa1.1-HEK 293 cells, the current density was not affected by cholesterol enrichment, but directly decreased by M?CD, suggesting that the down-regulation of BK channels by cholesterol depends on the auxiliary ?1-subunit. The reduced KCa1.1 channel protein expression was also observed in cultured human coronary artery smooth muscle cells with cholesterol enrichment using M?CD-cholesterol or LDL. These results demonstrate the novel information that cholesterol down-regulates BK channels by reducing KCa1.1 protein expression via increasing the channel protein degradation, and the effect is dependent on the auxiliary ?1-subunit.
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Project description:Background and purposeClemizole, a histamine H1 receptor antagonist has a potential therapeutic effect on hepatitis C infection and also potently inhibits TRPC5 ion channels. The aim of the present study was to investigate whether clemizole blocks cardiac K+ currents and thus affects cardiac repolarization.Experimental approachWhole-cell patch techniques was used to examine the effects of clemizole on hERG channel current, IKs and Kv 1.5 channel current in HEK 293 cell expression systems as well as on ventricular action potentials of guinea pig hearts. Isolated hearts from guinea pigs were used to determine the effect on the ECG.Key resultsClemizole decreased hERG current by blocking both open and closed states of the channel in a concentration-dependent manner (IC50 : 0.07 μM). The S631A, S636A, Y652A and F656V hERG mutant channels reduced the inhibitory effect of clemizole (IC50 : 0.82, 0.89, 1.49 and 2.98 μM, respectively), suggesting that clemizole is a pore blocker of hERG channels. Clemizole also moderately decreased IKs and human Kv 1.5 channel current. Moreover, clemizole increased the duration of the ventricular action potential in guinea pig hearts and the QTc interval in isolated perfused hearts from guinea pigs, in a concentration-dependent manner (0.1-1.0 μM).Conclusion and implicationsOur results provide the first evidence that clemizole potently blocks hERG channels, moderately inhibits cardiac IKs , delays cardiac repolarization and thereby prolongs QT interval. Thus, caution should be taken when clemizole is used as a TRPC5 channel blocker or for treating hepatitis C infection.
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Project description:TFEB in HEK293 cells by TET-OFF system (HEK293-PFL-TFEB).
| PRJNA384380 | ENA
Project description:The voltage dependent sodium channel Nav1.9, is expressed preferentially in peripheral sensory neurons and has been linked to human genetic pain disorders, which makes it target of interest for the development of new pain therapeutics. However, characterization of Nav1.9 pharmacology has been limited due in part to the historical difficulty of functionally expressing recombinant channels. Here we report the successful generation and characterization of human, mouse and rat Nav1.9 stably expressed in human HEK-293 cells. These cells exhibit slowly activating and inactivating inward sodium channel currents that have characteristics of native Nav1.9. Optimal functional expression was achieved by coexpression of Nav1.9 with β1/β2 subunits. While recombinantly expressed Nav1.9 was found to be sensitive to sodium channel inhibitors TC-N 1752 and tetracaine, potency was up to 100-fold less than reported for other Nav channel subtypes despite evidence to support an interaction with the canonical local anesthetic (LA) binding region on Domain 4 S6. Nav1.9 Domain 2 S6 pore domain contains a unique lysine residue (K799) which is predicted to be spatially near the local anesthetic interaction site. Mutation of this residue to the consensus asparagine (K799N) resulted in an increase in potency for tetracaine, but a decrease for TC-N 1752, suggesting that this residue can influence interaction of inhibitors with the Nav1.9 pore. In summary, we have shown that stable functional expression of Nav1.9 in the widely used HEK-293 cells is possible, which opens up opportunities to better understand channel properties and may potentially aid identification of novel Nav1.9 based pharmacotherapies.
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Project description:Three genes encode the small-conductance Ca(2+)-activated K(+) channels (SK channels). We have stably expressed hSK1 and rSK2 in HEK 293 cells and addressed the pharmacology of these subtypes using whole-cell patch clamp recordings. The bee venom peptide apamin blocked hSK1 as well as rSK2 with IC(50) values of 3.3 nM and 83 pM, respectively. The pharmacological separation between the subtypes was even more prominent when applying the scorpion peptide blocker scyllatoxin, which blocked hSK1 with an IC(50) value of 80 nM and rSK2 at 287 pM. The potent small molecule blockers showed little differentiation between the channel subtypes. The bis-quinolinium cyclophane UCL 1684 blocked hSK1 with an IC(50) value of 762 pM and rSK2 at 364 pM. The antiseptic compound dequalinium chloride blocked hSK1 and rSK2 with IC(50) values of 444 nM and 162 nM, respectively. The nicotinic acetylcholine receptor antagonist d-tubocurarine was found to block hSK1 and rSK2 with IC(50) values of 27 microM and 17 microM when measured at +80 mV. The inhibition by d-tubocurarine was voltage-dependent with increasing affinities at more hyperpolarized potentials. The GABA(A) receptor antagonist bicuculline methiodide also blocked hSK1 and rSK2 in a voltage-dependent manner with IC(50) values of 15 and 25 microM when measured at +80 mV. In conclusion, the pharmacological separation between SK channel subtypes expressed in mammalian cells is too small to support the notion that the apamin-insensitive afterhyperpolarization of neurones is mediated by hSK1.
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Project description:In order to identify the effects of transcription factor EB (TFEB) overexpression on the liver transcriptome, we performed Affymetrix GeneChip hybridization experiments on injected mice overexpressing TFEB specifically in the liver. For the analysis of the injected mice overexpressing TFEB, total RNA was extracted from the liver of three mice. RNA extracted from the liver of 3 not-injected mice was used as a control.
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2024-05-21 | PXD013758 | Pride
Project description:Total RNA samples from three biological replicates in which TFEB was transiently overexpressed in HeLa cells by transfection using a pcDNA3 vector. As negative control, we used total RNA samples from HeLa cells transfected with an empty pcDNA3 vector. TFEB transfection
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Project description:The transcription factor EB (TFEB) is a master regulator of lysosomal biogenesis and autophagy. We identify a distinct nuclear interactome of TFEB, with USP7 emerging as a key post-translational modulator of TFEB. Genetic depletion and inhibition of USP7 reveal its critical role in preserving TFEB stability within both nuclear and cytoplasmic compartments. Specifically, USP7 is identified as the deubiquitinase responsible for removing the K48-linked polyubiquitination signal from TFEB at lysine residues K116, K264, and K274, thereby preventing its proteasomal degradation. Functional assays demonstrate the involvement of USP7 in preserving TFEB-mediated transcriptional responses to nutrient deprivation, while also modulating autophagy flux and lysosome biogenesis. As USP7 is a deubiquitinase that protects TFEB from proteasomal degradation, these findings provide the foundation for therapeutic targeting of the USP7-TFEB axis in conditions characterized by TFEB dysregulation and metabolic abnormalities, particularly in certain cancers.
2024-09-17 | PXD055937 | Pride
Project description:Expression data from Ppara (peroxisome proliferator activated receptor alpha) KO mice injected with TFEB specifically in liver. In order to identify the effects of TFEB overexpression together with Ppara absence on the liver transcriptome, we performed Affymetrix Gene-Chip hybridization experiments for the injected mice For the analysis on the injected Ppara-KO mice overexpressing TFEB, total RNA was extracted from the liver of three mice; RNA extracted from the liver of not-injected mice was used as control.
2013-04-20 | E-GEOD-41140 | biostudies-arrayexpress