RÉSUMÉ
Ticks transmit a variety of pathogens, including rickettsia and viruses, when they feed on blood, afflicting humans and other animals. Bioactive components acting on inflammation, coagulation, and the immune system were reported to facilitate ticks' ability to suck blood and transmit tick-borne diseases. In this study, a novel peptide, IstTx, from an Ixodes scapularis cDNA library was analyzed. The peptide IstTx, obtained by recombinant expression and purification, selectively inhibited a potassium channel, TREK-1, in a dose-dependent manner, with an IC50 of 23.46 ± 0.22 µM. The peptide IstTx exhibited different characteristics from fluoxetine, and the possible interaction of the peptide IstTx binding to the channel was explored by molecular docking. Notably, extracellular acidification raised its inhibitory efficacy on the TREK-1 channel. Our results found that the tick-derived peptide IstTx blocked the TREK-1 channel and provided a novel tool acting on the potassium channel.
Sujet(s)
Peptides , Canaux potassiques à pores à domaines en tandem , Canaux potassiques à pores à domaines en tandem/métabolisme , Canaux potassiques à pores à domaines en tandem/génétique , Canaux potassiques à pores à domaines en tandem/antagonistes et inhibiteurs , Canaux potassiques à pores à domaines en tandem/composition chimique , Animaux , Humains , Peptides/pharmacologie , Peptides/composition chimique , Peptides/métabolisme , Ixodes/métabolisme , Simulation de docking moléculaire , Séquence d'acides aminés , Cellules HEK293 , Inhibiteurs des canaux potassiques/pharmacologie , Inhibiteurs des canaux potassiques/composition chimique , Tiques/métabolismeRÉSUMÉ
TREK-1 is a mechanosensitive channel activated by polyunsaturated fatty acids (PUFAs). Its activation is supposed to be linked to changes in membrane tension following PUFAs insertion. Here, we compared the effect of 11 fatty acids and ML402 on TREK-1 channel activation using the whole cell and the inside-out configurations of the patch-clamp technique. Firstly, TREK-1 activation by PUFAs is variable and related to the variable constitutive activity of TREK-1. We observed no correlation between TREK-1 activation and acyl chain length or number of double bonds suggesting that the bilayer-couple hypothesis cannot explain by itself the activation of TREK-1 by PUFAs. The membrane fluidity measurement is not modified by PUFAs at 10 µM. The spectral shift analysis in TREK-1-enriched microsomes indicates a KD,TREK1 at 44 µM of C22:6 n-3. PUFAs display the same activation and reversible kinetics than the direct activator ML402 and activate TREK-1 in both whole-cell and inside-out configurations of patch-clamp suggesting that the binding site of PUFAs is accessible from both sides of the membrane, as for ML402. Finally, we proposed a two steps mechanism: first, insertion into the membrane, with no fluidity or curvature modifications at 10 µM, and then interaction with TREK-1 channel to open it.
Sujet(s)
Acides gras insaturés , Canaux potassiques à pores à domaines en tandem , Canaux potassiques à pores à domaines en tandem/métabolisme , Acides gras insaturés/métabolisme , Acides gras insaturés/pharmacologie , Humains , Cellules HEK293 , Techniques de patch-clamp , Fluidité membranaire/effets des médicaments et des substances chimiquesRÉSUMÉ
The evolution of ion channel clustering at nodes of Ranvier enabled the development of complex vertebrate nervous systems. At mammalian nodes, the K+ leak channels TRAAK and TREK-1 underlie membrane repolarization. Despite the molecular similarities between nodes and the axon initial segment (AIS), TRAAK and TREK-1 are reportedly node-specific, suggesting a unique clustering mechanism. However, we show that TRAAK and TREK-1 are enriched at both nodes and AIS through a common mechanism. We identified a motif near the C-terminus of TRAAK that is necessary and sufficient for its clustering. The motif first evolved among cartilaginous fish. Using AnkyrinG (AnkG) conditional knockout mice, CRISPR/Cas9-mediated disruption of AnkG, co-immunoprecipitation, and surface recruitment assays, we show that TRAAK forms a complex with AnkG and that AnkG is necessary for TRAAK's AIS and nodal clustering. In contrast, TREK-1's clustering requires TRAAK. Our results expand the repertoire of AIS and nodal ion channel clustering mechanisms and emphasize AnkG's central role in assembling excitable domains.
Sujet(s)
Ankyrines , Axones , Souris knockout , Canaux potassiques à pores à domaines en tandem , Animaux , Canaux potassiques à pores à domaines en tandem/métabolisme , Canaux potassiques à pores à domaines en tandem/génétique , Axones/métabolisme , Souris , Ankyrines/métabolisme , Ankyrines/génétique , Noeuds de Ranvier/métabolisme , Humains , Motifs d'acides aminés , Évolution moléculaireRÉSUMÉ
Articular chondrocytes are the primary cells responsible for maintaining the integrity and functionality of articular cartilage, which is essential for smooth joint movement. A key aspect of their role involves mechanosensitive ion channels, which allow chondrocytes to detect and respond to mechanical forces encountered during joint activity; nonetheless, the variety of mechanosensitive ion channels involved in this process has not been fully resolved so far. Because some members of the two-pore domain potassium (K2P) channel family have been described as mechanosensors in other cell types, in this study, we investigate whether articular chondrocytes express such channels. RT-PCR analysis reveals the presence of TREK-1 and TREK-2 channels in these cells. Subsequent protein expression assessments, including Western blotting and immunohistochemistry, confirm the presence of TREK-1 in articular cartilage samples. Furthermore, whole-cell patch clamp assays demonstrate that freshly isolated chondrocytes exhibit currents attributable to TREK-1 channels, as evidenced by activation by arachidonic acid (AA) and ml335 and further inhibition by spadin. Additionally, exposure to hypo-osmolar shock activates currents, which can be attributed to the presence of TREK-1 channels, as indicated by their inhibition with spadin. Therefore, these findings highlight the expression of TREK channels in rat articular chondrocytes and suggest their potential involvement in regulating the integrity of cartilage extracellular matrix.
Sujet(s)
Cartilage articulaire , Chondrocytes , Canaux potassiques à pores à domaines en tandem , Animaux , Chondrocytes/métabolisme , Canaux potassiques à pores à domaines en tandem/métabolisme , Canaux potassiques à pores à domaines en tandem/génétique , Cartilage articulaire/métabolisme , Cartilage articulaire/cytologie , Rats , Cellules cultivées , Mâle , Mécanotransduction cellulaire , Techniques de patch-clampRÉSUMÉ
K2P potassium channels regulate excitability by affecting cellular resting membrane potential in the brain, cardiovascular system, immune cells, and sensory organs. Despite their important roles in anesthesia, arrhythmia, pain, hypertension, sleep, and migraine, the ability to control K2P function remains limited. Here, we describe a chemogenetic strategy termed CATKLAMP (covalent activation of TREK family K+ channels to clamp membrane potential) that leverages the discovery of a K2P modulator pocket site that reacts with electrophile-bearing derivatives of a TREK subfamily small-molecule activator, ML335, to activate the channel irreversibly. We show that CATKLAMP can be used to probe fundamental aspects of K2P function, as a switch to silence neuronal firing, and is applicable to all TREK subfamily members. Together, our findings exemplify a means to alter K2P channel activity that should facilitate molecular and systems level studies of K2P function and enable the search for new K2P modulators.
Sujet(s)
Canaux potassiques à pores à domaines en tandem , Humains , Canaux potassiques à pores à domaines en tandem/métabolisme , Canaux potassiques à pores à domaines en tandem/génétique , Animaux , Cellules HEK293 , Souris , Potentiels de membrane/effets des médicaments et des substances chimiques , Neurones/métabolisme , Neurones/effets des médicaments et des substances chimiques , RatsRÉSUMÉ
Breast cancer is the most prevalent malignancy and the most significant contributor to mortality in female oncology patients. Potassium Two Pore Domain Channel Subfamily K Member 1 (KCNK1) is differentially expressed in a variety of tumors, but the mechanism of its function in breast cancer is unknown. In this study, we found for the first time that KCNK1 was significantly up-regulated in human breast cancer and was correlated with poor prognosis in breast cancer patients. KCNK1 promoted breast cancer proliferation, invasion, and metastasis in vitro and vivo. Further studies unexpectedly revealed that KCNK1 increased the glycolysis and lactate production in breast cancer cells by binding to and activating lactate dehydrogenase A (LDHA), which promoted histones lysine lactylation to induce the expression of a series of downstream genes and LDHA itself. Notably, increased expression of LDHA served as a vicious positive feedback to reduce tumor cell stiffness and adhesion, which eventually resulted in the proliferation, invasion, and metastasis of breast cancer. In conclusion, our results suggest that KCNK1 may serve as a potential breast cancer biomarker, and deeper insight into the cancer-promoting mechanism of KCNK1 may uncover a novel therapeutic target for breast cancer treatment.
Sujet(s)
Tumeurs du sein , Prolifération cellulaire , Histone , Animaux , Femelle , Humains , Souris , Tumeurs du sein/anatomopathologie , Tumeurs du sein/génétique , Tumeurs du sein/métabolisme , Lignée cellulaire tumorale , Mouvement cellulaire/génétique , Prolifération cellulaire/génétique , Régulation de l'expression des gènes tumoraux , Glycolyse/génétique , Histone/métabolisme , L-Lactate dehydrogenase/métabolisme , L-Lactate dehydrogenase/génétique , Lactate dehydrogenase 5/métabolisme , Lactate dehydrogenase 5/génétique , Souris de lignée BALB C , Souris nude , Invasion tumorale , Métastase tumorale , Canaux potassiques à pores à domaines en tandem/métabolisme , Canaux potassiques à pores à domaines en tandem/génétique , Pronostic , Régulation positive/génétiqueRÉSUMÉ
TASK-3 generates a background K+ conductance which when inhibited by acidification depolarizes membrane potential and increases cell excitability. These channels sense pH by protonation of histidine residue H98, but recent evidence revealed that several other amino acid residues also contribute to TASK-3 pH sensitivity, suggesting that the pH sensitivity is determined by an intermolecular network. Here we use electrophysiology and molecular modeling to characterize the nature and requisite role(s) of multiple amino acids in pH sensing by TASK-3. Our results suggest that the pH sensor H98 and consequently pH sensitivity is influenced by remote amino acids that function as a hydrogen-bonding network to modulate ionic conductivity. Among the residues in the network, E30 and K79 are the most important for passing external signals near residue S31 to H98. The hydrogen-bond network plays a key role in selectivity or pH sensing in mTASK-3, and E30 and S31 in the network can modulate the conductive properties (E30) or reverse the pH sensitivity and selectivity of the channel (S31). Molecular dynamics simulations and pK1/2 calculation revealed that double mutants involving H98 + S31 primarily regulate the structure stability of the pore selectivity filter and pore loop regions, further strengthen the stability of the cradle suspension system, and alter the ionization state of E30 and K79, thereby preventing pore conformational change that normally occurs in response to varying extracellular pH. These results demonstrate that crucial residues in the hydrogen-bond network can remotely tune the pH sensing of mTASK-3 and may be a potential allosteric regulatory site for therapeutic molecule development.
Sujet(s)
Liaison hydrogène , Simulation de dynamique moléculaire , Canaux potassiques à pores à domaines en tandem , Concentration en ions d'hydrogène , Canaux potassiques à pores à domaines en tandem/composition chimique , Canaux potassiques à pores à domaines en tandem/métabolisme , Canaux potassiques à pores à domaines en tandem/génétique , Humains , Mutation , AnimauxRÉSUMÉ
Potassium channels have recently emerged as suitable target for the treatment of epileptic diseases. Among potassium channels, KCNT1 channels are the most widely characterized as responsible for several epileptic and developmental encephalopathies. Nevertheless, the medicinal chemistry of KCNT1 blockers is underdeveloped so far. In the present review, we describe and analyse the papers addressing the issue of KCNT1 blockers' development and identification, also evidencing the pros and the cons of the scientific approaches therein described. After a short introduction describing the epileptic diseases and the structure-function of potassium channels, we provide an extensive overview of the chemotypes described so far as KCNT1 blockers, and the scientific approaches used for their identification.
Sujet(s)
Chimie pharmaceutique , Épilepsie , Inhibiteurs des canaux potassiques , Humains , Inhibiteurs des canaux potassiques/composition chimique , Inhibiteurs des canaux potassiques/usage thérapeutique , Inhibiteurs des canaux potassiques/pharmacologie , Chimie pharmaceutique/méthodes , Épilepsie/traitement médicamenteux , Épilepsie/métabolisme , Relation structure-activité , Animaux , Anticonvulsivants/composition chimique , Anticonvulsivants/pharmacologie , Anticonvulsivants/usage thérapeutique , Protéines de tissu nerveux/antagonistes et inhibiteurs , Protéines de tissu nerveux/composition chimique , Protéines de tissu nerveux/métabolisme , Canaux potassiques à pores à domaines en tandem/antagonistes et inhibiteurs , Canaux potassiques à pores à domaines en tandem/métabolisme , Canaux potassiques à pores à domaines en tandem/composition chimique , Canaux potassiques voltage-dépendants/antagonistes et inhibiteurs , Canaux potassiques voltage-dépendants/métabolisme , Canaux potassiques activés par le sodiumRÉSUMÉ
BACKGROUND: Despite advances in understanding hypertension's genetic structure, how noncoding genetic variants influence it remains unclear. Studying their interaction with DNA methylation is crucial to deciphering this complex disease's genetic mechanisms. METHODS: We investigated the genetic and epigenetic interplay in hypertension using whole-genome bisulfite sequencing. Methylation profiling in 918 males revealed allele-specific methylation and methylation quantitative trait loci. We engineered rs1275988T/C mutant mice using CRISPR (clustered regularly interspaced short palindromic repeats)/Cas9 (CRISPR-associated protein 9), bred them for homozygosity, and subjected them to a high-salt diet. Telemetry captured their cardiovascular metrics. Protein-DNA interactions were elucidated using DNA pull-downs, mass spectrometry, and Western blots. A wire myograph assessed vascular function, and analysis of the Kcnk3 gene methylation highlighted the mutation's role in hypertension. RESULTS: We discovered that DNA methylation-associated genetic effects, especially in non-cytosine-phosphate-guanine (non-CpG) island and noncoding distal regulatory regions, significantly contribute to hypertension predisposition. We identified distinct methylation quantitative trait locus patterns in the hypertensive population and observed that the onset of hypertension is influenced by the transmission of genetic effects through the demethylation process. By evidence-driven prioritization and in vivo experiments, we unearthed rs1275988 in a cell type-specific enhancer as a notable hypertension causal variant, intensifying hypertension through the modulation of local DNA methylation and consequential alterations in Kcnk3 gene expression and vascular remodeling. When exposed to a high-salt diet, mice with the rs1275988C/C genotype exhibited exacerbated hypertension and significant vascular remodeling, underscored by increased aortic wall thickness. The C allele of rs1275988 was associated with elevated DNA methylation levels, driving down the expression of the Kcnk3 gene by attenuating Nr2f2 (nuclear receptor subfamily 2 group F member 2) binding at the enhancer locus. CONCLUSIONS: Our research reveals new insights into the complex interplay between genetic variations and DNA methylation in hypertension. We underscore hypomethylation's potential in hypertension onset and identify rs1275988 as a causal variant in vascular remodeling. This work advances our understanding of hypertension's molecular mechanisms and encourages personalized health care strategies.
Sujet(s)
Méthylation de l'ADN , Hypertension artérielle , Locus de caractère quantitatif , Animaux , Humains , Mâle , Souris , Pression sanguine/génétique , Épigenèse génétique , Prédisposition génétique à une maladie , Étude d'association pangénomique , Hypertension artérielle/génétique , Hypertension artérielle/métabolisme , Hypertension artérielle/physiopathologie , Souris de lignée C57BL , Canaux potassiques à pores à domaines en tandem/génétique , Canaux potassiques à pores à domaines en tandem/métabolisme , Chlorure de sodium alimentaire/effets indésirablesRÉSUMÉ
Astrocytes play an essential role in regulating synaptic transmission. This study describes a novel form of modulation of excitatory synaptic transmission in the mouse hippocampus by astrocytic G-protein-coupled receptors (GPCRs). We have previously described astrocytic glutamate release via protease-activated receptor-1 (PAR1) activation, although the regulatory mechanisms for this are complex. Through electrophysiological analysis and modeling, we discovered that PAR1 activation consistently increases the concentration and duration of glutamate in the synaptic cleft. This effect was not due to changes in the presynaptic glutamate release or alteration in glutamate transporter expression. However, blocking group II metabotropic glutamate receptors (mGluR2/3) abolished PAR1-mediated regulation of synaptic glutamate concentration, suggesting a role for this GPCR in mediating the effects of PAR1 activation on glutamate release. Furthermore, activation of mGluR2/3 causes glutamate release through the TREK-1 channel in hippocampal astrocytes. These data show that astrocytic GPCRs engage in a novel regulatory mechanism to shape the time course of synaptically-released glutamate in excitatory synapses of the hippocampus.
Sujet(s)
Astrocytes , Région CA1 de l'hippocampe , Acide glutamique , Souris de lignée C57BL , Récepteur de type PAR-1 , Récepteurs métabotropes au glutamate , Synapses , Animaux , Récepteurs métabotropes au glutamate/métabolisme , Astrocytes/métabolisme , Acide glutamique/métabolisme , Synapses/métabolisme , Région CA1 de l'hippocampe/métabolisme , Récepteur de type PAR-1/métabolisme , Souris , Potentiels post-synaptiques excitateurs/physiologie , Potentiels post-synaptiques excitateurs/effets des médicaments et des substances chimiques , Mâle , Transmission synaptique/physiologie , Transmission synaptique/effets des médicaments et des substances chimiques , Canaux potassiques à pores à domaines en tandem/métabolismeRÉSUMÉ
TREK2, a two-pore domain potassium channel, is recognized for its regulation by various stimuli, including lipids. While previous members of the TREK subfamily, TREK1 and TRAAK, have been investigated to elucidate their lipid affinity and selectivity, TREK2 has not been similarly studied in this regard. Our findings indicate that while TRAAK and TREK2 exhibit similarities in terms of electrostatics and share an overall structural resemblance, there are notable distinctions in their interaction with lipids. Specifically, SAPI(4,5)P2,1-stearoyl-2-arachidonoyl-sn-glycero-3-phospho-(1'-myo-inositol-4',5'-bisphosphate) exhibits a strong affinity for TREK2, surpassing that of dOPI(4,5)P2,1,2-dioleoyl-sn-glycero-3-phospho-(1'-myo-inositol-4',5'-bisphosphate), which differs in its acyl chains. TREK2 displays lipid binding preferences not only for the headgroup of lipids but also toward the acyl chains. Functional studies draw a correlation for lipid binding affinity and activity of the channel. These findings provide important insight into elucidating the molecular prerequisites for specific lipid binding to TREK2 important for function.
Sujet(s)
Canaux potassiques à pores à domaines en tandem , Canaux potassiques à pores à domaines en tandem/composition chimique , Canaux potassiques à pores à domaines en tandem/métabolisme , Humains , Liaison aux protéines , Spectrométrie de masse/méthodes , Animaux , Modèles moléculaires , Électricité statique , Canaux potassiquesRÉSUMÉ
BACKGROUND: The metastasis of tumors into bone tissue typically leads to intractable pain that is both very disabling and particularly difficult to manage. We investigated here whether riluzole could have beneficial effects for the treatment of prostate cancer-induced bone pain and how it could influence the development of bone metastasis. METHODS: We used a bone pain model induced by intratibial injection of human PC3 prostate cancer cells into male SCID mice treated or not with riluzole administered in drinking water. We also used riluzole in vitro to assess its possible effect on PC3 cell viability and functionality, using patch-clamp. RESULTS: Riluzole had a significant preventive effect on both evoked and spontaneous pain involving the TREK-1 potassium channel. Riluzole did not interfere with PC3-induced bone loss or bone remodeling in vivo. It also significantly decreased PC3 cell viability in vitro. The antiproliferative effect of riluzole is correlated with a TREK-1-dependent membrane hyperpolarization in these cells. CONCLUSION: The present data suggest that riluzole could be very useful to manage evoked and spontaneous hypersensitivity in cancer-induced bone pain and has no significant adverse effect on cancer progression.
Sujet(s)
Analgésiques , Tumeurs osseuses , Douleur cancéreuse , Prolifération cellulaire , Souris SCID , Canaux potassiques à pores à domaines en tandem , Riluzole , Riluzole/pharmacologie , Animaux , Canaux potassiques à pores à domaines en tandem/métabolisme , Mâle , Tumeurs osseuses/traitement médicamenteux , Tumeurs osseuses/métabolisme , Tumeurs osseuses/secondaire , Tumeurs osseuses/anatomopathologie , Tumeurs osseuses/complications , Humains , Douleur cancéreuse/traitement médicamenteux , Douleur cancéreuse/métabolisme , Analgésiques/pharmacologie , Prolifération cellulaire/effets des médicaments et des substances chimiques , Cellules PC-3 , Souris , Survie cellulaire/effets des médicaments et des substances chimiques , Tumeurs de la prostate/traitement médicamenteux , Tumeurs de la prostate/anatomopathologie , Tumeurs de la prostate/métabolisme , Lignée cellulaire tumoraleRÉSUMÉ
BACKGROUND AND AIM: Sepsis-induced acute lung injury (ALI) is a complex and life-threatening condition lacking specific and efficient clinical treatments. Extracellular histones, identified as a novel type of damage-associated molecular patterns, have been implicated in the inflammatory process of ALI. However, further elucidation is needed regarding the precise mechanism through which extracellular histones induce inflammation. The aim of this study was to investigate whether extracellular histones can activate NLRP3 inflammasome-mediated inflammation in alveolar macrophages (AMs) by affecting TWIK2-dependent potassium efflux. METHODS AND RESULTS: We conducted experiments using cecal ligation and puncture (CLP) C57BL/6 mice and extracellular histone-stimulated LPS-primed MH-S cells. The results demonstrated a significant increase in the levels of extracellular histones in the plasma and bronchoalveolar lavage fluid (BALF) of CLP mice. Furthermore, neutralizing extracellular histone mitigated lung injury and inflammation in CLP-induced ALI mice. In vitro studies confirmed that extracellular histones upregulated the expression of NLRP3 inflammasome activation-related proteins in MH-S cells, and this effect was dependent on increased potassium efflux mediated by the TWIK2 channel on the plasma membrane. Moreover, extracellular histones directly triggered a substantial influx of calcium, leading to increased Rab11 activity and facilitating the trafficking and location of TWIK2 to the plasma membrane. CONCLUSION: These findings underscore the critical role of extracellular histone-induced upregulation of TWIK2 expression on the plasma membrane of alveolar macrophages (AMs). This upregulation leads to potassium efflux and subsequent activation of the NLRP3 inflammasome, ultimately exacerbating lung inflammation and injury during sepsis.
Sujet(s)
Lésion pulmonaire aigüe , Histone , Macrophages alvéolaires , Souris de lignée C57BL , Protéine-3 de la famille des NLR contenant un domaine pyrine , Potassium , Sepsie , Animaux , Protéine-3 de la famille des NLR contenant un domaine pyrine/métabolisme , Sepsie/complications , Sepsie/métabolisme , Sepsie/immunologie , Potassium/métabolisme , Macrophages alvéolaires/métabolisme , Macrophages alvéolaires/immunologie , Lésion pulmonaire aigüe/métabolisme , Lésion pulmonaire aigüe/étiologie , Lésion pulmonaire aigüe/immunologie , Lésion pulmonaire aigüe/anatomopathologie , Histone/métabolisme , Mâle , Souris , Liquide de lavage bronchoalvéolaire , Canaux potassiques à pores à domaines en tandem/métabolisme , Lignée cellulaire , Canaux potassiques/métabolisme , Protéines G rab/métabolisme , Inflammasomes/métabolisme , LipopolysaccharidesRÉSUMÉ
Potassium ion (K+) is one of the most essential nutrients for the growth and development of tobacco (Nicotiana tabacum L.), however, the molecular regulation of K+ concentration in tobacco remains unclear. In this study, a two-pore K (TPK) channel gene NtTPKa was cloned from tobacco, and NtTPKa protein contains the unique K+ selection motif GYGD and its transmembrane region primarily locates in the tonoplast membrane. The expression of NtTPKa gene was significantly increased under low-potassium stress conditions. The concentrations of K+ in tobacco were significantly increased in the NtTPKa RNA interference lines and CRISPR/Cas9 knockout mutants. In addition, the transport of K+ by NtTPKa was validated using patch clamp technique, and the results showed that NtTPKa channel protein exclusively transported K+ in a concentration-dependent manner. Together, our results strongly suggested that NtTPKa is a key gene in maintaining K+ homeostasis in tobacco, and it could provide a new genetic resource for increasing the concentration of K+ in tobacco.
Sujet(s)
Régulation de l'expression des gènes végétaux , Nicotiana , Protéines végétales , Potassium , Nicotiana/génétique , Nicotiana/métabolisme , Potassium/métabolisme , Protéines végétales/génétique , Protéines végétales/métabolisme , Canaux potassiques à pores à domaines en tandem/métabolisme , Canaux potassiques à pores à domaines en tandem/génétique , Systèmes CRISPR-Cas , Canaux potassiques/métabolisme , Canaux potassiques/génétiqueRÉSUMÉ
The two-pore domain potassium (K2P) channels TREK-1 and TREK-2 link neuronal excitability to a variety of stimuli including mechanical force, lipids, temperature and phosphorylation. This regulation involves the C-terminus as a polymodal stimulus sensor and the selectivity filter (SF) as channel gate. Using crystallographic up- and down-state structures of TREK-2 as a template for full atomistic molecular dynamics (MD) simulations, we reveal that the SF in down-state undergoes inactivation via conformational changes, while the up-state structure maintains a stable and conductive SF. This suggests an atomistic mechanism for the low channel activity previously assigned to the down state, but not evident from the crystal structure. Furthermore, experimentally by using (de-)phosphorylation mimics and chemically attaching lipid tethers to the proximal C-terminus (pCt), we confirm the hypothesis that moving the pCt towards the membrane induces the up-state. Based on MD simulations, we propose two gating pathways by which movement of the pCt controls the stability (i.e., conductivity) of the filter gate. Together, these findings provide atomistic insights into the SF gating mechanism and the physiological regulation of TREK channels by phosphorylation.
Sujet(s)
Ouverture et fermeture des portes des canaux ioniques , Simulation de dynamique moléculaire , Canaux potassiques à pores à domaines en tandem , Canaux potassiques à pores à domaines en tandem/métabolisme , Canaux potassiques à pores à domaines en tandem/composition chimique , Canaux potassiques à pores à domaines en tandem/génétique , Humains , Phosphorylation , Domaines protéiques , Cytosol/métabolisme , Animaux , Cellules HEK293 , Cristallographie aux rayons XRÉSUMÉ
BACKGROUND: Research has shown a connection between vasculogenic mimicry (VM) and cancer progression. However, the functions of genes related to VM in the emergence and progression of TNBC have not been completely elucidated. METHODS: A survival risk model was constructed by screening biomarkers using DESeq2 and WGCNA based on public TNBC transcriptome data. Furthermore, gene set enrichment analysis was performed, and tumor microenvironment and drug sensitivity were analyzed. The selected biomarkers were validated via quantitative PCR detection, immunohistochemical staining, and protein detection in breast cancer cell lines. Biomarkers related to the proliferation and migration of TNBC cells were validated via in vitro experiments. RESULTS: The findings revealed that 235 target genes were connected to the complement and coagulation cascade pathways. The risk score was constructed using KCND2, NRP1, and VSTM4. The prognosis model using the risk score and pathological T stage yielded good validation results. The clinical risk of TNBC was associated with the angiogenesis signaling pathway, and the low-risk group exhibited better sensitivity to immunotherapy. Quantitative PCR and immunohistochemistry indicated that the expression levels of KCND2 in TNBC tissues were higher than those in adjacent nontumor tissues. In the TNBC cell line, the protein expression of KCND2 was increased. Knockdown of KCND2 and VSTM4 inhibited the proliferation and migration of TNBC cells in vitro. CONCLUSIONS: In this study, three VM-related biomarkers were identified, including KCND2, NRP1, and VSTM4. These findings are likely to aid in deepening our understanding of the regulatory mechanism of VM in TNBC.
Sujet(s)
Marqueurs biologiques tumoraux , Néovascularisation pathologique , Tumeurs du sein triple-négatives , Humains , Tumeurs du sein triple-négatives/génétique , Tumeurs du sein triple-négatives/anatomopathologie , Tumeurs du sein triple-négatives/métabolisme , Femelle , Pronostic , Néovascularisation pathologique/génétique , Néovascularisation pathologique/métabolisme , Marqueurs biologiques tumoraux/génétique , Marqueurs biologiques tumoraux/métabolisme , Lignée cellulaire tumorale , Régulation de l'expression des gènes tumoraux , Microenvironnement tumoral/génétique , Prolifération cellulaire/génétique , Neuropiline 1/génétique , Neuropiline 1/métabolisme , Mouvement cellulaire/génétique , Transcriptome , Canaux potassiques à pores à domaines en tandem/génétique , Canaux potassiques à pores à domaines en tandem/métabolismeRÉSUMÉ
Stable and entrainable physiological circadian rhythms are crucial for overall health and well-being. The suprachiasmatic nucleus (SCN), the primary circadian pacemaker in mammals, consists of diverse neuron types that collectively generate a circadian profile of electrical activity. However, the mechanisms underlying the regulation of endogenous neuronal excitability in the SCN remain unclear. Two-pore domain potassium channels (K2P), including TASK-3, are known to play a significant role in maintaining SCN diurnal homeostasis by inhibiting neuronal activity at night. In this study, we investigated the role of TASK-3 in SCN circadian neuronal regulation and behavioural photoentrainment using a TASK-3 global knockout mouse model. Our findings demonstrate the importance of TASK-3 in maintaining SCN hyperpolarization during the night and establishing SCN sensitivity to glutamate. Specifically, we observed that TASK-3 knockout mice lacked diurnal variation in resting membrane potential and exhibited altered glutamate sensitivity both in vivo and in vitro. Interestingly, despite these changes, the mice lacking TASK-3 were still able to maintain relatively normal circadian behaviour.
Sujet(s)
Rythme circadien , Souris knockout , Canaux potassiques à pores à domaines en tandem , Noyau suprachiasmatique , Animaux , Rythme circadien/physiologie , Noyau suprachiasmatique/physiologie , Noyau suprachiasmatique/métabolisme , Canaux potassiques à pores à domaines en tandem/métabolisme , Canaux potassiques à pores à domaines en tandem/génétique , Souris , Mâle , Souris de lignée C57BL , Comportement animal/physiologie , Acide glutamique/métabolisme , Neurones/physiologie , Neurones/métabolisme , Potentiels de membrane/physiologie , Canaux potassiquesRÉSUMÉ
Oxytocin, a significant pleiotropic neuropeptide, regulates psychological stress adaptation and social communication, as well as peripheral actions, such as uterine contraction and milk ejection. Recently, a Japanese Kampo medicine called Kamikihito (KKT) has been reported to stimulate oxytocin neurons to induce oxytocin secretion. Two-pore-domain potassium channels (K2P) regulate the resting potential of excitable cells, and their inhibition results in accelerated depolarization that elicits neuronal and endocrine cell activation. We assessed the effects of KKT and 14 of its components on a specific K2P, the potassium channel subfamily K member 2 (TREK-1), which is predominantly expressed in oxytocin neurons in the central nervous system (CNS). KKT inhibited the activity of TREK-1 induced via the channel activator ML335. Six of the 14 components of KKT inhibited TREK-1 activity. Additionally, we identified that 22 of the 41 compounds in the six components exhibited TREK-1 inhibitory effects. In summary, several compounds included in KKT partially activated oxytocin neurons by inhibiting TREK-1. The pharmacological effects of KKT, including antistress effects, may be partially mediated through the oxytocin pathway.
Sujet(s)
Neurones , Ocytocine , Canaux potassiques à pores à domaines en tandem , Animaux , Humains , Souris , Médicaments issus de plantes chinoises/pharmacologie , Médicaments issus de plantes chinoises/composition chimique , Médecine kampo , Neurones/métabolisme , Neurones/effets des médicaments et des substances chimiques , Ocytocine/pharmacologie , Ocytocine/métabolisme , Canaux potassiques à pores à domaines en tandem/métabolisme , Canaux potassiques à pores à domaines en tandem/antagonistes et inhibiteursRÉSUMÉ
Potassium channels of the Two-Pore Domain (K2P) subfamily, KCNK1-KCNK18, play crucial roles in controlling the electrical activity of many different cell types and represent attractive therapeutic targets. However, the identification of highly selective small molecule drugs against these channels has been challenging due to the high degree of structural and functional conservation that exists not only between K2P channels, but across the whole K+ channel superfamily. To address the issue of selectivity, here we generate camelid antibody fragments (nanobodies) against the TREK-2 (KCNK10) K2P K+ channel and identify selective binders including several that directly modulate channel activity. X-ray crystallography and CryoEM data of these nanobodies in complex with TREK-2 also reveal insights into their mechanisms of activation and inhibition via binding to the extracellular loops and Cap domain, as well as their suitability for immunodetection. These structures facilitate design of a biparatropic inhibitory nanobody with markedly improved sensitivity. Together, these results provide important insights into TREK channel gating and provide an alternative, more selective approach to modulation of K2P channel activity via their extracellular domains.
Sujet(s)
Canaux potassiques à pores à domaines en tandem , Anticorps à domaine unique , Canaux potassiques à pores à domaines en tandem/métabolisme , Anticorps à domaine unique/métabolisme , Anticorps à domaine unique/immunologie , Anticorps à domaine unique/composition chimique , Humains , Cristallographie aux rayons X , Animaux , Cryomicroscopie électronique , Cellules HEK293 , Modèles moléculairesRÉSUMÉ
Neuropathic pain can occur during the prediabetic stage, even in the absence of hyperglycemia. The presence of prediabetic neuropathic pain (PDNP) poses challenges to the management of individuals with prediabetes. However, the mechanisms underlying this pain remain unclear. This study aims to investigate the underlying mechanism and identify potential therapeutic targets of PDNP. A prediabetic animal model induced by a high-energy diet exhibits both mechanical allodynia and thermal hyperalgesia. Furthermore, hyperexcitability and decreased potassium currents are observed in the dorsal root ganglion (DRG) neurons of these rats. TREK1 and TREK2 channels, which belong to the two-pore-domain K+ channel (K2P) family and play an important role in controlling cellular excitability, are downregulated in DRG neurons. Moreover, this alteration is modulated by Sortilin, a molecular partner that modulates the expression of TREK1. The overexpression of Sortilin negatively affects the expression of TREK1 and TREK2, leading to increased neuronal excitability in the DRG and enhanced peripheral pain sensitivity in rats. Moreover, the downregulation of Sortilin or activation of TREK1 and TREK2 channels by genetic or pharmacological approaches can alleviate PDNP. Therefore, targeting the Sortilin-mediated TREK1/2 pathway may provide a therapeutic approach for ameliorating PDNP.