KV1.5–KV 1.3 Recycling Is PKC-Dependent

KV1.5 channel function is modified by different regulatory subunits. KVβ1.3 subunits assemble with KV1.5 channels and induce a fast and incomplete inactivation. Inhibition of PKC abolishes the KVβ1.3-induced fast inactivation, decreases the amplitude of the current KV1.5–KVβ1.3 and modifies their pharmacology likely due to changes in the traffic of KV1.5–KVβ1.3 channels in a PKC-dependent manner. In order to analyze this hypothesis, HEK293 cells were transfected with KV1.5–KVβ1.3 channels, and currents were recorded by whole-cell configuration of the patch-clamp technique. The presence of KV1.5 in the membrane was analyzed by biotinylation techniques, live cell imaging and confocal microscopy approaches. PKC inhibition resulted in a decrease of 33 ± 7% of channels in the cell surface due to reduced recycling to the plasma membrane, as was confirmed by confocal microscopy. Live cell imaging indicated that PKC inhibition almost abolished the recycling of the KV1.5–KVβ1.3 channels, generating an accumulation of channels into the cytoplasm. All these results suggest that the trafficking regulation of KV1.5–KVβ1.3 channels is dependent on phosphorylation by PKC and, therefore, they could represent a clinically relevant issue, mainly in those diseases that exhibit modifications in PKC activity.This research was funded by Ministerio de Ciencia e Innovación (MICINN) Spain SAF2016-75021-R and PID2019-104366RB-C21 (to C.V. and T.G.), the Instituto de Salud Carlos III CIBERCV program CB/11/00222 (to C.V.), and the Consejo Superior de Investigaciones Científicas grants: PIE 201820E104 and 2019AEP148 (to C.V.). The cost of this publication was paid in part by funds from the European Fund for Economic and Regional Development (FEDER). A.M. holds a postdoctoral contract at CNIC. A.d.l.C. and D.A.P. held CSIC contracts. A.d.B.-B. holds an MICINN predoctoral contract (BES-2017-080184

Modulation of KV4.3-KChIP2 Channels by IQM-266: Role of DPP6 and KCNE2

The transient outward potassium current (Itof) is generated by the activation of KV4 channels assembled with KChIP2 and other accessory subunits (DPP6 and KCNE2). To test the hypothesis that these subunits modify the channel pharmacology, we analyzed the electrophysiological effects of (3-(2-(3-phenoxyphenyl)acetamido)-2-naphthoic acid) (IQM-266), a new KChIP2 ligand, on the currents generated by KV4.3/KChIP2, KV4.3/KChIP2/DPP6 and KV4.3/KChIP2/KCNE2 channels. CHO cells were transiently transfected with cDNAs codifying for different proteins (KV4.3/KChIP2, KV4.3/KChIP2/DPP6 or KV4.3/KChIP2/KCNE2), and the potassium currents were recorded using the whole-cell patch-clamp technique. IQM-266 decreased the maximum peak of KV4.3/KChIP2, KV4.3/KChIP2/DPP6 and KV4.3/KChIP2/KCNE2 currents, slowing their time course of inactivation in a concentration-, voltage-, time- and use-dependent manner. IQM-266 produced an increase in the charge in KV4.3/KChIP2 channels that was intensified when DPP6 was present and abolished in the presence of KCNE2. IQM-266 induced an activation unblocking effect during the application of trains of pulses to cells expressing KV4.3/KChIP2 and KV4.3/KChIP2/KCNE2, but not in KV4.3/KChIP2/DPP6 channels. Overall, all these results are consistent with a preferential IQM-266 binding to an active closed state of Kv4.3/KChIP2 and Kv4.3/KChIP2/KCNE2 channels, whereas in the presence of DPP6, IQM-266 binds preferentially to an inactivated state. In conclusion, DPP6 and KCNE2 modify the pharmacological response of KV4.3/KChIP2 channels to IQM-266

Resolvin D2 Attenuates Cardiovascular Damage in Angiotensin II-Induced Hypertension.

Background: Resolution of inflammation is orchestrated by specialized proresolving lipid mediators (SPMs), and this would be impaired in some cardiovascular diseases. Among SPMs, resolvins (Rv) have beneficial effects in cardiovascular pathologies, but little is known about their effect on cardiovascular damage in hypertension. Methods: Aorta, small mesenteric arteries, heart, and peritoneal macrophages were taken from C57BL/6J mice, infused or not with angiotensin II (AngII; 1.44 mg/kg/day, 14 days) in presence or absence of resolvin D2 (RvD2) (100 ng/mice, every second day) starting 1 day before or 7 days after AngII infusion. Results: Enzymes and receptors involved in SPMs biosynthesis and signaling were increased in aorta or heart from AngII-infused mice. We also observed a differential regulation of SPMs in heart from these mice. Preventive treatment with RvD2 partially avoided AngII-induced hypertension and protected the heart and large and small vessels against functional and structural alterations induced by AngII. RvD2 increased the availability of vasoprotective factors, modified SPMs profile, decreased cardiovascular fibrosis, and increased the infiltration of pro-resolving macrophages. When administered in hypertensive animals with established cardiovascular damage, RvD2 partially improved cardiovascular function and structure, decreased fibrosis, reduced the infiltration of neutrophils, and shifted macrophage phenotype toward a pro-resolving phenotype. Conclusions: There is a disbalance between proinflammatory and resolution mediators in hypertension. RvD2 protects cardiovascular function and structure when administered before and after the development of hypertension by modulating vascular factors, fibrosis and inflammation. Activating resolution mechanisms by treatment with RvD2 may represent a novel therapeutic strategy for the treatment of hypertensive cardiovascular disease.pre-print362 K

New approaches for the identification of KChIP2 ligands to study the KV4.3 channelosome in atrial fibrillati

Resumen del trabajo presentado en el VIII Congreso Red Española de Canales iónico, celebrado en Alicante (España) del 24 al 27 de mayo de 2022.Ion channels are macromolecular complexes present in the plasma membrane and in intracellular organelles of the cells, where they play important functions. The dysfunction of these channels results in several disorders named channelopathies, which represent a challenge for study and treatment.[1] We are focused on voltage-gated potassium channels, specifically on KV4.3. Kv4.3 is expressed in smooth muscle, heart and brain. Within the heart, Kv4.3 channels generate the transient outward potassium current (ITO). However, ITO characteristics are only observed when Kv4.3 assemble with accessory subunits as KChIP2 and DPP6. KV4.3 channelosome play a key role in atrial fibrillation (AF),the most common cardiac arrhythmia, with an estimated prevalence in the general population of 1.5–2%. However, current antiarrhythmic drugs for AF prevention have limited efficacy and considerable potential for adverse effects.[2] KChIP2 (Potassium Channel Interacting Protein 2) belongs to the calcium binding protein superfamily. It is the KChIP member predominantly expressed in heart and a key regulator of cardiac action potential duration. The identification of novel KChIP2 ligands could be useful to understand the role of KV4.3 channelosome in AF and it could help to discover new treatments for AF. [3] In this regard, structure-based virtual screening could be an important tool to accelerate the identification of novel KChIP2 ligands. In this communication, we will describe a multidisciplinary approach that, starting with a structurebased virtual screening, followed by an iterative process of synthesis/biological evaluation/docking studies, has led to the identification of new KChIP2 ligands.PID2019-104366RB-C21, PID2019-104366RB-C22, PID2020-114256RB-I00 and PID2020-119805RB-I00 grants funded by MCIN/AEI/10.13039/501100011033; and PIE202180E073 and 2019AEP148 funded by CSIC. C.V.B. holds PRE2020-093542 FPI grant funded by MCIN/AEI/10.13039/501100011033. PGS was recipient of an FPU grant (FPU17/02731). AB-B holds BES-2017-080184 FPI grant and A.P-L.holds RYC2018-023837-I grant both funded by MCIN/ AEI/ 10.13039/501100011033 and by “ESF Investing in your future

New approaches for the identification of KChIP2 ligands to study the KV4.3 channelosome in atrial fibrillati

Resumen del trabajo presentado en el VIII Congreso Red Española de Canales iónico, celebrado en Alicante (España) del 24 al 27 de mayo de 2022.Ion channels are macromolecular complexes present in the plasma membrane and in intracellular organelles of the cells, where they play important functions. The dysfunction of these channels results in several disorders named channelopathies, which represent a challenge for study and treatment.[1] We are focused on voltage-gated potassium channels, specifically on KV4.3. Kv4.3 is expressed in smooth muscle, heart and brain. Within the heart, Kv4.3 channels generate the transient outward potassium current (ITO). However, ITO characteristics are only observed when Kv4.3 assemble with accessory subunits as KChIP2 and DPP6. KV4.3 channelosome play a key role in atrial fibrillation (AF),the most common cardiac arrhythmia, with an estimated prevalence in the general population of 1.5–2%. However, current antiarrhythmic drugs for AF prevention have limited efficacy and considerable potential for adverse effects.[2] KChIP2 (Potassium Channel Interacting Protein 2) belongs to the calcium binding protein superfamily. It is the KChIP member predominantly expressed in heart and a key regulator of cardiac action potential duration. The identification of novel KChIP2 ligands could be useful to understand the role of KV4.3 channelosome in AF and it could help to discover new treatments for AF. [3] In this regard, structure-based virtual screening could be an important tool to accelerate the identification of novel KChIP2 ligands. In this communication, we will describe a multidisciplinary approach that, starting with a structurebased virtual screening, followed by an iterative process of synthesis/biological evaluation/docking studies, has led to the identification of new KChIP2 ligands.PID2019-104366RB-C21, PID2019-104366RB-C22, PID2020-114256RB-I00 and PID2020-119805RB-I00 grants funded by MCIN/AEI/10.13039/501100011033; and PIE202180E073 and 2019AEP148 funded by CSIC. C.V.B. holds PRE2020-093542 FPI grant funded by MCIN/AEI/10.13039/501100011033. PGS was recipient of an FPU grant (FPU17/02731). AB-B holds BES-2017-080184 FPI grant and A.P-L.holds RYC2018-023837-I grant both funded by MCIN/ AEI/ 10.13039/501100011033 and by “ESF Investing in your future

Routing of Kv7.1 to endoplasmic reticulum plasma membrane junctions

AIM: The voltage-gated Kv7.1 channel, in association with the regulatory subunit KCNE1, contributes to the I(Ks) current in the heart. However, both proteins travel to the plasma membrane using different routes. While KCNE1 follows a classical Golgi-mediated anterograde pathway, Kv7.1 is located in endoplasmic reticulum-plasma membrane junctions (ER-PMjs), where it associates with KCNE1 before being delivered to the plasma membrane. METHODS: To characterize the channel routing to these spots we used a wide repertoire of methodologies, such as protein expression analysis (i.e. protein association and biotin labeling), confocal (i.e. immunocytochemistry, FRET, and FRAP), and dSTORM microscopy, transmission electron microscopy, proteomics, and electrophysiology. RESULTS: We demonstrated that Kv7.1 targeted ER-PMjs regardless of the origin or architecture of these structures. Kv2.1, a neuronal channel that also contributes to a cardiac action potential, and JPHs, involved in cardiac dyads, increased the number of ER-PMjs in nonexcitable cells, driving and increasing the level of Kv7.1 at the cell surface. Both ER-PMj inducers influenced channel function and dynamics, suggesting that different protein structures are formed. Although exhibiting no physical interaction, Kv7.1 resided in more condensed clusters (ring-shaped) with Kv2.1 than with JPH4. Moreover, we found that VAMPs and AMIGO, which are Kv2.1 ancillary proteins also associated with Kv7.1. Specially, VAP B, showed higher interaction with the channel when ER-PMjs were stimulated by Kv2.1. CONCLUSION: Our results indicated that Kv7.1 may bind to different structures of ER-PMjs that are induced by different mechanisms. This variable architecture can differentially affect the fate of cardiac Kv7.1 channels

Sigma-1 receptor modulation fine-tunes KV1.5 channels and impacts pulmonary vascular function

KV1.5 channels are key players in the regulation of vascular tone and atrial excitability and their impairment is associated with cardiovascular diseases including pulmonary arterial hypertension (PAH) and atrial fibrillation (AF). Unfortunately, pharmacological strategies to improve KV1.5 channel function are missing. Herein, we aimed to study whether the chaperone sigma-1 receptor (S1R) is able to regulate these channels and represent a new strategy to enhance their function. By using different electrophysiological and molecular techniques in X. laevis oocytes and HEK293 cells, we demonstrate that S1R physically interacts with KV1.5 channels and regulate their expression and function. S1R induced a bimodal regulation of KV1.5 channel expression/activity, increasing it at low concentrations and decreasing it at high concentrations. Of note, S1R agonists (PRE084 and SKF10047) increased, whereas the S1R antagonist BD1047 decreased, KV1.5 expression and activity. Moreover, PRE084 markedly increased KV1.5 currents in pulmonary artery smooth muscle cells and attenuated vasoconstriction and proliferation in pulmonary arteries. We also show that both KV1.5 channels and S1R, at mRNA and protein levels, are clearly downregulated in samples from PAH and AF patients. Moreover, the expression of both genes showed a positive correlation. Finally, the ability of PRE084 to increase KV1.5 function was preserved under sustained hypoxic conditions, as an in vitro PAH model. Our study provides insight into the key role of S1R in modulating the expression and activity of KV1.5 channels and highlights the potential role of this chaperone as a novel pharmacological target for pathological conditions associated with KV1.5 channel dysfunction.This work was supported by Ministerio de Ciencia e Inovación [SAF2016-75021-R; PID2019-104366RB-C21 to C.V. and T.G., PID2020-117939RB-I00 to A.C., PID2019-107363RB-I00 to F.P.V.]; by CIBERCV, by Instituto de Salud Carlos III [CB/11/00222 to C.V.], by CSIC [PIE201820E104; 2019AEP148 to C.V.]. BES-2017-080184 (to A.B.-B.), funded by MCIN/AEI/ 10.13039/501100011033 and by “ESF Investing in your future” funded by Ministerio de Ciencia e Innovación. A.V.-Z., M.B.-N., A.B.-B. and M.V-E. was awarded with predoctoral fellowships: FPI-UAM, CSIC, FPI and FPU predoctoral contracts, respectively. A.V.-Z. was awarded with a Short-term fellowship from the European Molecular Biology Organization (EMBO).Peer reviewe

Modulation of KV4.3-KChIP2 Channels by IQM-266: Role of DPP6 and KCNE2

The transient outward potassium current (Itof) is generated by the activation of KV4 chan- nels assembled with KChIP2 and other accessory subunits (DPP6 and KCNE2). To test the hypothesis that these subunits modify the channel pharmacology, we analyzed the electrophysiological effects of (3-(2-(3-phenoxyphenyl)acetamido)-2-naphthoic acid) (IQM-266), a new KChIP2 ligand, on the currents generated by KV4.3/KChIP2, KV4.3/KChIP2/DPP6 and KV4.3/KChIP2/KCNE2 channels. CHO cells were transiently transfected with cDNAs codifying for different proteins (KV4.3/KChIP2, KV4.3/KChIP2/DPP6 or KV4.3/KChIP2/KCNE2), and the potassium currents were recorded using the whole-cell patch-clamp technique. IQM-266 decreased the maximum peak of KV4.3/KChIP2, KV4.3/KChIP2/DPP6 and KV4.3/KChIP2/KCNE2 currents, slowing their time course of inactivation in a concentration-, voltage-, time- and use-dependent manner. IQM-266 produced an increase in the charge in KV4.3/KChIP2 channels that was intensified when DPP6 was present and abolished in the presence of KCNE2. IQM-266 induced an activation unblocking effect during the applica- tion of trains of pulses to cells expressing KV4.3/KChIP2 and KV4.3/KChIP2/KCNE2, but not in KV4.3/KChIP2/DPP6 channels. Overall, all these results are consistent with a preferential IQM-266 binding to an active closed state of Kv4.3/KChIP2 and Kv4.3/KChIP2/KCNE2 channels, whereas in the presence of DPP6, IQM-266 binds preferentially to an inactivated state. In conclusion, DPP6 and KCNE2 modify the pharmacological response of KV4.3/KChIP2 channels to IQM-266.This publication is the results of the: Grants SAF2016-75021-R (to C.V.), RTI2018-097189-B- C22 (to M.M.-M.) and BIO2017-89523-R (to A.A.) funded by MCIN/AEI/10.13039/501100011033 and by “ERDF A way of making Europe”; Grants PID2019-104366RB-C21 (to C.V.), PID2019-104366RB- C22 (to M.G.-R.), PID2020-114256RB-I00 (to A.O. and J.A.G.-V.), PID2020-119805RB-I00 (to A.A.) funded by MCIN/AEI/10.13039/501100011033; Grant A-FQM-386-UGR20 funded by FEDER/Junta de Andalucía-Consejería de Transformación Económica, Industria, Conocimiento (to J.A.G.-V.); Grant CB/11/00222 funded by Instituto de Salud Carlos III CIBERCV (to C.V.); Grants PIE202180E073 (to M.M.-M. and M.G.-R.), PIE201820E104 and 2019AEP148 (to C.V.) funded by Consejo Superior de Investigaciones Científicas. Grants BES-2017-080184 (to A.d.B.-B.), BES-2010-036573 (to P.C.), PRE2018- 083280 (to M.D.-M.) and RYC2018-023837-I (to A.P.-L.) funded by MCIN/AEI/10.13039/501100011033 and by “ESF Investing in your future”; Grant FPU17/02731 (to P.G.S.) funded by Ministerio de Ciencia e Innovación.Peer reviewe

Pan-Cancer Analysis of lncRNA Regulation Supports Their Targeting of Cancer Genes in Each Tumor Context

Long noncoding RNAs (lncRNAs) are commonly dys-regulated in tumors, but only a handful are known toplay pathophysiological roles in cancer. We inferredlncRNAs that dysregulate cancer pathways, onco-genes, and tumor suppressors (cancer genes) bymodeling their effects on the activity of transcriptionfactors, RNA-binding proteins, and microRNAs in5,185 TCGA tumors and 1,019 ENCODE assays.Our predictions included hundreds of candidateonco- and tumor-suppressor lncRNAs (cancerlncRNAs) whose somatic alterations account for thedysregulation of dozens of cancer genes and path-ways in each of 14 tumor contexts. To demonstrateproof of concept, we showed that perturbations tar-geting OIP5-AS1 (an inferred tumor suppressor) andTUG1 and WT1-AS (inferred onco-lncRNAs) dysre-gulated cancer genes and altered proliferation ofbreast and gynecologic cancer cells. Our analysis in-dicates that, although most lncRNAs are dysregu-lated in a tumor-specific manner, some, includingOIP5-AS1, TUG1, NEAT1, MEG3, and TSIX, synergis-tically dysregulate cancer pathways in multiple tumorcontexts

Genomic, Pathway Network, and Immunologic Features Distinguishing Squamous Carcinomas

This integrated, multiplatform PanCancer Atlas study co-mapped and identified distinguishing molecular features of squamous cell carcinomas (SCCs) from five sites associated with smokin