N-(2-Hydroxyphenyl)-1-[3-(2-oxo-2,3-dihydro-1Hbenzimidazol-1-yl)propyl]piperidine-4-Carboxamide (D2AAK4), a Multi-Target Ligand of Aminergic GPCRs, as a Potential Antipsychotic

N-(2-hydroxyphenyl)-1-[3-(2-oxo-2,3-dihydro-1H-benzimidazol -1-yl)propyl]piperidine-4-carboxamide (D2AAK4) is a multitarget ligand of aminergic G protein-coupled receptors (GPCRs) identified in structure-based virtual screening. Here we present detailed in vitro, in silico and in vivo investigations of this virtual hit. D2AAK4 has an atypical antipsychotic profile and low affinity to off-targets. It interacts with aminergic GPCRs, forming an electrostatic interaction between its protonatable nitrogen atom and the conserved Asp 3.32 of the receptors. At the dose of 100 mg/kg D2AAK4 decreases amphetamine-induced hyperactivity predictive of antipsychotic activity, improves memory consolidation in passive avoidance test and has anxiogenic properties in elevated plus maze test (EPM). Further optimization of the virtual hit D2AAK4 will be aimed to balance its multitarget profile and to obtain analogs with anxiolytic activity.The research was performed under OPUS grant from National Science Center (NCN, Poland), grant number 2017/27/B/NZ7/01767 (to A.A.K). Calculations were partially performed under a computational grant by Interdisciplinary Center for Mathematical and Computational Modeling (ICM), Warsaw, Poland, grant number G30-18 (to A.A.K.), under resources and licenses from CSC, Finland (to A.A.K). In vitro pharmacology assays were performed with support from the Spanish Ministry of Economy and Competitiveness (MINECO) (grant number SAF2014-57138-C2-1-R to M.C.). A.G.S. acknowledges funding from XUNTA de Galicia (Spain)S

Interaction of Bupropion with Muscle-Type Nicotinic Acetylcholine Receptors in Different Conformational States

To characterize the binding sites and the mechanisms of inhibition of bupropion on muscle-type nicotinic acetylcholine receptors (AChRs), structural and functional approaches were used. The results established that bupropion: (a) inhibits epibatidine-induced Ca2+ influx in embryonic muscle AChRs, (b) inhibits adult muscle AChR macroscopic currents in the resting/activatable state with ~100-fold higher potency compared to that in the open state, (c) increases desensitization rate of adult muscle AChRs from the open state and impairs channel opening from the resting state, (d) inhibits [3H]TCP and [3H]imipramine binding to the desensitized/carbamylcholine-bound Torpedo AChR with higher affinity compared to the resting/α-bungarotoxin-bound AChR, (e) binds to the Torpedo AChR in either state mainly by an entropy–driven process, and (f) interacts with a binding domain located between the serine (position 6’) and valine (position 13’) rings, by a network of van der Waals, hydrogen bond, and polar interactions. Collectively our data indicate that bupropion first binds to the resting AChR, decreasing the probability of ion channel opening. The remnant fraction of open ion channels is subsequently decreased by accelerating the desensitization process. Bupropion interacts with a luminal binding domain shared with PCP that is located between the serine and valine rings, and this interaction is mediated mainly by an entropy-driven process.Fil: Arias, Hugo Rubén. Midwestern University; Estados Unidos. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Gumilar, Fernanda Andrea. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Investigaciones Bioquímicas de Bahía Blanca. Universidad Nacional del Sur. Instituto de Investigaciones Bioquímicas de Bahía Blanca; ArgentinaFil: Rosenberg, Avraham. National Institutes of Health; Estados UnidosFil: Targowska Duda, Katarzyna M.. Medical University of Lublin; PoloniaFil: Feuerbach, Dominik. Novartis Institutes for Biomedical Research; SuizaFil: Jozwiak, Krzysztof. Medical University of Lublin; PoloniaFil: Moaddel, Ruin. National Institutes of Health; Estados UnidosFil: Wainer, Irving W.. National Institutes of Health; Estados UnidosFil: Bouzat, Cecilia Beatriz. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Investigaciones Bioquímicas de Bahía Blanca. Universidad Nacional del Sur. Instituto de Investigaciones Bioquímicas de Bahía Blanca; Argentin

Coronaridine congeners inhibit human α3β4 Nicotinic Acetylcholine Receptors by interacting with luminal and non-luminal sites

To characterize the interaction of coronaridine congeners with human (h) α3β4 nicotinic acetylcholine receptors (AChRs), structural and functional approaches were used. The results established that coronaridine congeners inhibit (±)-epibatidine-induced Ca2+ influx in hα3β4 AChRs with the following potency (IC50’s in μM) sequence: (-)-ibogamine (0.62 ± 0.23) ~ (+)-catharanthine (0.68 ± 0.10) > (-)-iboganine (0.95 ± 0.10) > (±)-18-methoxycoronaridine [(±)-18-MC] (1.47 ± 0.21) > (-)-voacangine (2.28 ± 0.33) > (±)-18-methylaminocoronaridine [(±)-18-MAC] (2.62 ± 0.57 μM) ~ (±)-18-hydroxycoronaridine [(±)-18-HC] (2.81 ± 0.54) > (-)-noriboganine (6.82 ± 0.78). A good linear correlation (r2 = 0.771) between the calculated IC50 values and their polar surface area was found, suggesting that this is an important structural feature for the activity of coronaridine congeners. The radioligand competition results indicate that (±)-18-MC and (-)-iboganine partially inhibit [3H]imipramine binding by an allosteric mechanism. Molecular docking and dynamics results suggest that protonated (-)-18-MC binds to luminal [between the phenylalanine/valine (position 13’) and serine (position 6’) rings], non-luminal (between 4-M1, 3/4-M2, and3-M3), and intersubunit (between 3-M1 and 3/4-M2) sites. Collectively our data indicate that coronaridine congeners inhibit hα3β4 AChRs by blocking the ion channel’s lumen and probably by additional negative allosteric mechanisms by interacting with a series of non-luminal sites

Recent Advances and Applications of Molecular Docking to G Protein-Coupled Receptors

The growing number of studies on G protein-coupled receptors (GPCRs) family are a source of noticeable improvement in our understanding of the functioning of these proteins. GPCRs are responsible for a vast part of signaling in vertebrates and, as such, invariably remain in the spotlight of medicinal chemistry. A deeper insight into the underlying mechanisms of interesting phenomena observed in GPCRs, such as biased signaling or allosteric modulation, can be gained with experimental and computational studies. The latter play an important role in this process, since they allow for observations on scales inaccessible for most other methods. One of the key steps in such studies is proper computational reconstruction of actual ligand-receptor or protein-protein interactions, a process called molecular docking. A number of improvements and innovative applications of this method were documented recently. In this review, we focus particularly on innovations in docking to GPCRs

Is the antidepressant activity of selective serotonin reuptake inhibitors mediated by nicotinic acetylcholine receptors?

It is generally assumed that selective serotonin reuptake inhibitors (SSRIs) induce antidepressant activity by inhibiting serotonin (5-HT) reuptake transporters, thus elevating synaptic 5-HT levels and, finally, ameliorates depression symptoms. New evidence indicates that SSRIs may also modulate other neurotransmitter systems by inhibiting neuronal nicotinic acetylcholine receptors (nAChRs), which are recognized as important in mood regulation. There is a clear and strong association between major depression and smoking, where depressed patients smoke twice as much as the normal population. However, SSRIs are not efficient for smoking cessation therapy. In patients with major depressive disorder, there is a lower availability of functional nAChRs, although their amount is not altered, which is possibly caused by higher endogenous ACh levels, which consequently induce nAChR desensitization. Other neurotransmitter systems have also emerged as possible targets for SSRIs. Studies on dorsal raphe nucleus serotoninergic neurons support the concept that SSRI-induced nAChR inhibition decreases the glutamatergic hyperstimulation observed in stress conditions, which compensates the excessive 5-HT overflow in these neurons and, consequently, ameliorates depression symptoms. At the molecular level, SSRIs inhibit different nAChR subtypes by noncompetitive mechanisms, including ion channel blockade and induction of receptor desensitization, whereas α9α10 nAChRs, which are peripherally expressed and not directly involved in depression, are inhibited by competitive mechanisms. According to the functional and structural results, SSRIs bind within the nAChR ion channel at high-affinity sites that are spread out between serine and valine rings. In conclusion, SSRI-induced inhibition of a variety of nAChRs expressed in different neurotransmitter systems widens the complexity by which these antidepressants may act clinically.Fil: Arias, Hugo R.. Oklahoma State University; Estados UnidosFil: Targowska Duda, Katarzyna M.. Medical University Of Lublin; PoloniaFil: García Colunga, Jesús. Universidad Nacional Autónoma de México; MéxicoFil: Ortells, Marcelo Oscar. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad de Morón; Argentin

Antidepressant activity in mice elicited by 3-furan-2-yl-N-p-tolyl-acrylamide, a positive allosteric modulator of the α7 nicotinic acetylcholine receptor

The objective of the current study is to determine whether 3-furan-2-yl-N-p-tolyl-acrylamide (PAM-2), a positive allosteric modulator of 7 nicotinic receptors (AChRs), produces antidepressant-like behavior in mice, and reactivates desensitized 7 AChRs expressed in CH3-7 cells. Mice from both sexes were injected (i.p.) with PAM-2 (1.0 mg/kg) on a daily basis for three weeks. Forced swim tests (FSTs) were performed on Day 1 and Day 7 to determine the acute and subchronic effects of PAM-2, respectively, and on Days 14 and 21 to determine its chronic activity. To examine the residual effects after drug treatment, a withdrawal period of two more weeks was continued with FSTs performed on Day 28 and 35. Our results indicate that: (1) PAM-2 does not induce acute antidepressant effects in male or female mice, (2) PAM-2 induce antidepressant effects in mice from both sexes after one (subchronic) and two (chronic) weeks, whereas at the third week (chronic), the antidepressant effect is decreased in male and increased in female mice. Since PAM-2 does not influence the locomotor activity of mice, the observed antidepressant activity is not driven by nonspecific motor-stimulant actions, (3) the residual antidepressant effect mediated by PAM-2 after one week of treatment cessation is observed only in female mice, and finally the Ca2+ influx results indicate that (4) PAM-2 can reactivate desensitized 7 AChRs. Our results clearly indicate that PAM-2 elicits antidepressant activity, probably by enhancing the activity of the endogenous neurotransmitter acetylcholine on 7 AChRs, without inducing receptor desensitization, and that this activity is gender-dependent. This is the first time that an antidepressant activity is described for an α7 PAM, supporting further studies as potential therapeutic medications for depressive states

Efficacy of Dabrafenib and Trametinib in a Patient with Squamous-Cell Carcinoma, with Mutation p.D594G in <i>BRAF</i> and p.R461* in <i>NF1</i> Genes—A Case Report with Literature Review

The 3rd class of BRAF (B-Raf Proto-Oncogene, Serine/Threonine Kinase) variants including G466, D594, and A581 mutations cause kinase death or impaired kinase activity. It is unlikely that RAF (Raf Proto-Oncogene, Serine/Threonine Kinase) inhibitors suppress ERK (Extracellular Signal-Regulated Kinase) signaling in class 3 mutant-driven tumors due to the fact that they preferentially inhibit activated BRAF V600 mutants. However, there are suggestions that class 3 mutations are still associated with enhanced RAS/MAPK (RAS Proto-Oncogene, GTPase/Mitogen-Activated Protein Kinase) activation, potentially due to other mechanisms such as the activation of growth factor signaling or concurrent MAPK pathway mutations, e.g., RAS or NF1 (Neurofibromin 1). A 75-year-old male patient with squamous-cell cancer (SqCC) of the lung and with metastases to the kidney and mediastinal lymph nodes received chemoimmunotherapy (expression of Programmed Cell Death 1 Ligand 1 (PD-L1) on 2% of tumor cells). The chemotherapy was limited due to the accompanying myelodysplastic syndrome (MDS), and pembrolizumab monotherapy was continued for up to seven cycles. At the time of progression, next-generation sequencing was performed and a c.1781A>G (p.Asp594Gly) mutation in the BRAF gene, a c.1381C>T (p.Arg461Ter) mutation in the NF1 gene, and a c.37C>T (p.Gln13Ter) mutation in the FANCC gene were identified. Combined therapy with BRAF (dabrafenib) and MEK (trametinib) inhibitors was used, which resulted in the achievement of partial remission of the primary lesion and lung nodules and the stabilization of metastatic lesions in the kidney and bones. The therapy was discontinued after five months due to myelosuppression associated with MDS. The molecular background was decisive for the patient’s fate. NSCLC patients with non-V600 mutations in the BRAF gene rarely respond to anti-BRAF and anti-MEK therapy. The achieved effectiveness of the treatment could be related to a mutation in the NF1 tumor suppressor gene. The loss of NF1 function causes the excessive activation of KRAS and overactivity of the signaling pathway containing BRAF and MEK, which were the targets of the therapy. Moreover, the mutation in the FANCC gene was probably related to MDS development. The NGS technique was crucial for the qualification to treatment and the prediction of the NSCLC course in our patient. The mutations in two genes—the BRAF oncogene and the NF1 tumor suppressor gene—were the reason for the use of dabrafenib and trametinib treatment. The patients achieved short-term disease stabilization. This proved that coexisting mutations in these genes affect the disease course and treatment efficacy

Pharmacological and molecular studies on the interaction of varenicline with different nicotinic acetylcholine receptor subtypes. Potential mechanism underlying partial agonism at human 42 and 34 subtypes

In order to determine the structural components underlying differences in affinity, potency, and selectivity of varenicline for several human (h) nicotinic acetylcholine receptors (AChRs), functional and structural experiments were performed. The Ca2+ influx results established that: (a) varenicline activates (EC50s in μM) AChR subtypes with the following rank sequence: hα7 (0.18 ± 0.02) > hα4β4 (0.37 ± 0.08) > hα4β2 (1.30 ± 0.18) > hα3β4 (6.4 ± 1.2) >>> hα1β1γδ (>100); (b) varenicline binds to AChR subtypes with the following affinity order (Kis): hα4β2 (0.090 ± 0.007 nM) ~ hα4β4 (0.121 ± 0.004 nM) > hα3β4 (13 ± 1 nM) > hα7 (77 ± 6 nM) >>> Tα1β1γδ (116 ± 8 μM). The molecular docking results indicating that more hydrogen bond interactions are apparent for 4-containing AChRs in comparison to other AChRs may explain the observed higher affinity; and that (c) varenicline is a full agonist at hα7 (101%) and hα4β4 (93%), and a partial agonist at hα4β2 (20%) and hα3β4 (45%), relative to ()-epibatidine. The allosteric sites found at the extracellular domain (EXD) of h34 and h42 AChRs could explain the partial agonistic activity of varenicline on these AChR subtypes. Molecular dynamics simulations show that the interaction of varenicline to each allosteric site decreases the capping of Loop C at the hα4β2 AChR, suggesting that these allosteric interactions limit the initial step in the gating process. In conclusion, we propose that in addition to hα4β2 AChRs, hα4β4 AChRs can be considered as potential targets for the clinical activity of varenicline, and that the allosteric interactions at the h34- and h42-EXDs are alternative mechanisms underlying partial agonism at these AChRs

Structural and functional interaction of (+)-2-(N-tert-butylamino)-3’-iodo-4’-azidopropiophenone, a photoactivatable bupropion derivative, with nicotinic acetylcholine receptors

The pharmacological properties of S-(+)-2-(N-tert-butylamino)-3’-iodo-4’-azidopropiophenone [(+)-SADU3-72], a photoactivatable analog of bupropion (BP), were characterized at different muscle nicotinic acetylcholine receptors (AChRs) by functional and structural approaches. Ca2+ influx results indicate that (+)-SADU3-72 is 17- and 6-fold more potent than BP in inhibiting human (h) embryonic (hα1β1γδ) and adult (hα1β1δ) muscle AChRs. (+)-SADU3-72 binds with high affinity to the [3H]TCP site at either the resting or desensitized Torpedo AChRs, whereas BP has higher affinity for the desensitized AChR. Molecular docking results indicate that both SADU3-72 isomers interact with the valine (position 13’) and serine (position 6’) rings. However, an additional domain, between the outer (position 20’) and valine rings, is observed in Torpedo AChR ion channels. Our results indicate that the azido group of (+)-SADU3-72 may enhance the interaction with polar groups as well as the formation of hydrogen bonds, supporting the observed higher potency and affinity of (+)-SADU3-72 compared to BP. Collectively these results are consistent with a model where BP/SADU3-72 and TCP bind to overlapping sites within the lumen of muscle AChR ion channels. Based on these results, we believe that (+)-SADU3-72 represents a promising photoprobe for mapping the BP binding site, especially within the resting AChR ion channel