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

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

Evaluation of appendicitis risk prediction models in adults with suspected appendicitis

Background Appendicitis is the most common general surgical emergency worldwide, but its diagnosis remains challenging. The aim of this study was to determine whether existing risk prediction models can reliably identify patients presenting to hospital in the UK with acute right iliac fossa (RIF) pain who are at low risk of appendicitis. Methods A systematic search was completed to identify all existing appendicitis risk prediction models. Models were validated using UK data from an international prospective cohort study that captured consecutive patients aged 16–45 years presenting to hospital with acute RIF in March to June 2017. The main outcome was best achievable model specificity (proportion of patients who did not have appendicitis correctly classified as low risk) whilst maintaining a failure rate below 5 per cent (proportion of patients identified as low risk who actually had appendicitis). Results Some 5345 patients across 154 UK hospitals were identified, of which two‐thirds (3613 of 5345, 67·6 per cent) were women. Women were more than twice as likely to undergo surgery with removal of a histologically normal appendix (272 of 964, 28·2 per cent) than men (120 of 993, 12·1 per cent) (relative risk 2·33, 95 per cent c.i. 1·92 to 2·84; P < 0·001). Of 15 validated risk prediction models, the Adult Appendicitis Score performed best (cut‐off score 8 or less, specificity 63·1 per cent, failure rate 3·7 per cent). The Appendicitis Inflammatory Response Score performed best for men (cut‐off score 2 or less, specificity 24·7 per cent, failure rate 2·4 per cent). Conclusion Women in the UK had a disproportionate risk of admission without surgical intervention and had high rates of normal appendicectomy. Risk prediction models to support shared decision‐making by identifying adults in the UK at low risk of appendicitis were identified

It takes two to tango: Unraveling a new post-translational modification involved in SnRK2.6 activation

3 pags., 1 fig.he authors are funded by the Agencia Estatal de Investigacion of the Spanish Ministry of Science and Innovation with grant BIO2017-89523-

Bivalve Diversity on the Continental Shelf and Deep Sea of the Perdido Fold Belt, Northwest Gulf of Mexico, Mexico

Mollusk diversity in coastal areas of the Gulf of Mexico (GOM) has been studied extensively, but this is not the case for deep-water habitats. We present the first quantitative characterization of mollusks in shallow and deep waters of the Perdido Fold Belt. The data came from two research cruises completed in 2017. Sediment samples were collected from 56 sites using a 0.25-m2 box corer. We tested hypotheses about spatial patterns of α, β, and γ-diversity of bivalves in two water-depth zones, the continental shelf (43–200 m) and bathyal zone (375–3563 m). A total of 301 bivalves belonging to 39 species were identified. The two zones display similar levels of γ-diversity, but host different bivalve assemblages. In general, α-diversity was higher on the continental shelf, whereas β-diversity was higher in the bathyal zone. These patterns can be explained by the higher input of carbon (energy) to the near-coast shelf zone, as well as by the greater topographic complexity of habitats in the bathyal zone. These results enabled us to propose redirection of sampling efforts for environmental characterization from continental zones to the deep-water zone, especially in the context of environmental assessments during oil and gas exploration and production

Stereoselective electrochemical reduction of imazapyr in aqueous media without chiral auxiliaries

The electrochemical reduction of imazapyr at the static mercury drop electrode was studied by cyclic voltammetry as a function of pH in aqueous buffered media. The process leads to the 2,3=CvN double bond reduction in the imidazoline moiety in all media. The products have been isolated by controlled-potential electrolyses and identified by high performance liquid chromatography-tandem mass spectrometry measurements and H-1-NMR, C-13-NMR, and IR spectra. Although no chiral auxiliary was used, a moderate diasteroisomeric excess was observed. The diasteromeric ratio depends on pH of the electrolyse

Structure-Based Modulation of the Ligand Sensitivity of a Tomato Dimeric Abscisic Acid Receptor Through a Glu to Asp Mutation in the Latch Loop

12 pags., 6 figs. -- This article is part of the Research Topic: Structural Bioinformatics and Biophysical Approaches for Understanding the Plant Responses to Biotic and Abiotic StressThe binding of the plant phytohormone Abscisic acid (ABA) to the family of ABA receptors (PYR/PYL/RCAR) triggers plant responses to abiotic stress. Thus, the implementation of genetic or chemical strategies to modulate PYR/PYL activity might be biotechnologically relevant. We have employed the available structural information on the PYR/PYL receptors to design SlPYL1, a tomato receptor, harboring a single point mutation that displays enhanced ABA dependent and independent activity. Interestingly, crystallographic studies show that this mutation is not directly involved in ABA recognition or in the downstream phosphatase (PP2C) inhibitory interaction, rather, molecular dynamic based ensemble refinement restrained by crystallographic data indicates that it enhances the conformational variability required for receptor activation and it is involved in the stabilization of an active form of the receptor. Moreover, structural studies on this receptor have led to the identification of niacin as an ABA antagonist molecule in vivo. We have found that niacin blocks the ABA binding site by mimicking ABA receptor interactions, and the niacin interaction inhibits the biochemical activity of the receptor.The authors are funded by the Agencia Estatal de Investigación of the Spanish Ministry of Science and Innovation with grant number PID2020-119805RB-I00 to AA and grant PID2020-113100RB-I00 to PR funded by MCIN/AEI/10.13039/501100011033, and PRE2018-083280 to MD-M

Study of kv4.3 channelosome: novel kchip2 ligands as pharmacological tools

Trabajo presentado en el VIII Symposia of medicinal chemistry young researchers, celebrado en Barcelona (España) el 22 de julio 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. Within the heart, KV4.3 channels generate the transient outward potassium current (ITO). However, ITO characteristics are only observed when KV4.3 assembles 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. Novel KChIP2 ligands could be a useful pharmacological tool to understand the role of KV4.3 channelosome in AF and it could help to discover new treatments for AF. [3] In this communication, we will describe a multidisciplinary approach that, starting with a structure-based 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”