Shahar Azar, Shiran Udi, Adi Drori, Rivka Hadar, Alina Nemirovski, Kiran V. Vemuri, Maya Miller, Dana Sherill-Rofe, Yhara Arad, Devorah Gur-Wahnon, Xiaoling Li, Alexandros Makriyannis, Danny Ben-Zvi, Yuval Tabach, Iddo Z. Ben-Dov, and Joseph Tam. 2020. “Reversal of diet-induced hepatic steatosis by peripheral CB1 receptor blockade in mice is p53/miRNA-22/SIRT1/PPAR$\alpha$ dependent.” Molecular Metabolism, 42. Abstract
Objective: The endocannabinoid (eCB) system is increasingly recognized as being crucially important in obesity-related hepatic steatosis. By activating the hepatic cannabinoid-1 receptor (CB1R), eCBs modulate lipogenesis and fatty acid oxidation. However, the underlying molecular mechanisms are largely unknown. Methods: We combined unbiased bioinformatics techniques, mouse genetic manipulations, multiple pharmacological, molecular, and cellular biology approaches, and genomic sequencing to systematically decipher the role of the hepatic CB1R in modulating fat utilization in the liver and explored the downstream molecular mechanisms. Results: Using an unbiased normalized phylogenetic profiling analysis, we found that the CB1R evolutionarily coevolves with peroxisome proliferator-activated receptor-alpha (PPAR$\alpha$), a key regulator of hepatic lipid metabolism. In diet-induced obese (DIO) mice, peripheral CB1R blockade (using AM6545) induced the reversal of hepatic steatosis and improved liver injury in WT, but not in PPAR$\alpha$−/− mice. The antisteatotic effect mediated by AM6545 in WT DIO mice was accompanied by increased hepatic expression and activity of PPAR$\alpha$ as well as elevated hepatic levels of the PPAR$\alpha$-activating eCB-like molecules oleoylethanolamide and palmitoylethanolamide. Moreover, AM6545 was unable to rescue hepatic steatosis in DIO mice lacking liver sirtuin 1 (SIRT1), an upstream regulator of PPAR$\alpha$. Both of these signaling molecules were modulated by the CB1R as measured in hepatocytes exposed to lipotoxic conditions or treated with CB1R agonists in the absence/presence of AM6545. Furthermore, using microRNA transcriptomic profiling, we found that the CB1R regulated the hepatic expression, acetylation, and transcriptional activity of p53, resulting in the enhanced expression of miR-22, which was found to specifically target SIRT1 and PPAR$\alpha$. Conclusions: We provide strong evidence for a functional role of the p53/miR-22/SIRT1/PPAR$\alpha$ signaling pathway in potentially mediating the antisteatotic effect of peripherally restricted CB1R blockade.
Rawnaq Esa, Eliana Steinberg, Dvir Dror, Ouri Schwob, Mehrdad Khajavi, Miriam Maoz, Yael Kinarty, Adi Inbal, Aviad Zick, and Ofra Benny. 2020. “The Role of Methionine Aminopeptidase 2 in Lymphangiogenesis.” International journal of molecular sciences, 21, 14. Abstract
During the metastasis process, tumor cells invade the blood circulatory system directly from venous capillaries or indirectly via lymphatic vessels. Understanding the relative contribution of each pathway and identifying the molecular targets that affect both processes is critical for reducing cancer spread. Methionine aminopeptidase 2 (MetAp2) is an intracellular enzyme known to modulate angiogenesis. In this study, we investigated the additional role of MetAp2 in lymphangiogenesis. A histological staining of tumors from human breast-cancer donors was performed in order to detect the level and the localization of MetAp2 and lymphatic capillaries. The basal enzymatic level and activity in vascular and lymphatic endothelial cells were compared, followed by loss of function studies determining the role of MetAp2 in lymphangiogenesis in vitro and in vivo. The results from the histological analyses of the tumor tissues revealed a high MetAp2 expression, with detectable sites of co-localization with lymphatic capillaries. We showed slightly reduced levels of the MetAp2 enzyme and MetAp2 mRNA expression and activity in primary lymphatic cells when compared to the vascular endothelial cells. The genetic and biochemical manipulation of MetAp2 confirmed the dual activity of the enzyme in both vascular and lymphatic remodulation in cell function assays and in a zebrafish model. We found that cancer-related lymphangiogenesis is inhibited in murine models following MetAp2 inhibition treatment. Taken together, our study provides an indication that MetAp2 is a significant contributor to lymphangiogenesis and carries a dual role in both vascular and lymphatic capillary formation. Our data suggests that MetAp2 inhibitors can be effectively used as anti-metastatic broad-spectrum drugs.
Manish Kumar Tripathi, Maryam Kartawy, and Haitham Amal. 2020. “The role of nitric oxide in brain disorders: Autism spectrum disorder and other psychiatric, neurological, and neurodegenerative disorders.” Redox biology, 34, Pp. 101567. Abstract
Nitric oxide (NO) is a multifunctional signalling molecule and a neurotransmitter that plays an important role in physiological and pathophysiological processes. In physiological conditions, NO regulates cell survival, differentiation and proliferation of neurons. It also regulates synaptic activity, plasticity and vesicle trafficking. NO affects cellular signalling through protein S-nitrosylation, the NO-mediated posttranslational modification of cysteine thiols (SNO). SNO can affect protein activity, protein-protein interaction and protein localization. Numerous studies have shown that excessive NO and SNO can lead to nitrosative stress in the nervous system, contributing to neuropathology. In this review, we summarize the role of NO and SNO in the progression of neurodevelopmental, psychiatric and neurodegenerative disorders, with special attention to autism spectrum disorder (ASD). We provide mechanistic insights into the contribution of NO in diverse brain disorders. Finally, we suggest that pharmacological agents that can inhibit or augment the production of NO as well as new approaches to modulate the formation of SNO-proteins can serve as a promising approach for the treatment of diverse brain disorders.
Igor Khaliulin, Maryam Kartawy, and Haitham Amal. 2020. “Sex Differences in Biological Processes and Nitrergic Signaling in Mouse Brain.” Biomedicines, 8, 5. Abstract
Nitric oxide (NO) represents an important signaling molecule which modulates the functions of different organs, including the brain. S-nitrosylation (SNO), a post-translational modification that involves the binding of the NO group to a cysteine residue, is a key mechanism of nitrergic signaling. Most of the experimental studies are carried out on male animals. However, significant differences exist between males and females in the signaling mechanisms. To investigate the sex differences in the SNO-based regulation of biological functions and signaling pathways in the cortices of 6-8-weeks-old mice, we used the mass spectrometry technique, to identify S-nitrosylated proteins, followed by large-scale computational biology. This work revealed significant sex differences in the NO and SNO-related biological functions in the cortices of mice for the first-time. The study showed significant SNO-induced enrichment of the synaptic processes in female mice, but enhanced SNO-related cytoskeletal processes in the male mice. Proteins, which were S-nitrosylated in the cortices of mice of both groups, were more abundant in the female brain. Finally, we investigated the shared molecular processes that were found in both sexes. This study presents a mechanistic insight into the role of S-nitrosylation in both sexes and provides strong evidence of sex difference in many biological processes and signalling pathways, which will open future research directions on sex differences in neurological disorders.
Philip Lazarovici. 2020. “Snake- and Spider-Venom-Derived Toxins as Lead Compounds for Drug Development.” Methods in molecular biology (Clifton, N.J.), 2068, Pp. 3–26. Abstract
Snake and spider venoms have been developed by nature as a defense mechanism against predators or to immobilize their prey by blocking the cardiovascular, respiratory, and/or nervous systems. Consequently, predators are deterred from approaching their prey by painful sensations. At a molecular level, the targeted physiological systems are blocked or stimulated by peptide toxins which, once injected into the body, modulate, though not exclusively, important cell membrane ion channels and receptors. Millions of years of constant evolution have led to the evolvement of complex venom libraries of optimized protein toxins, making them more potent, more selective, resistant to proteases, less immunogenic, and improved in terms of pharmacokinetic (PK) properties. The resulting advantage is that they induce long-term and potent pharmacodynamic (PD) effects toward unique molecular targets of therapeutic importance such as coagulation cascade proteins, receptors, and ionic channels. This optimization process has been enabled by the diversification of peptide sequences (mainly by gene duplication) and an upscaling of the complexity of toxin peptide scaffold structures, through implementation of multiple disulfide bridges and sequence-active motif diversification, leading to a wide diversity of chemical structures. This combination of pharmaceutical properties has made venom toxins valuable both as pharmacological tools and as leads for drug development. These highly tunable molecules can be tailored to achieve desirable biocompatibility and biodegradability with simultaneously selective and potent therapeutic effects. This brief overview provides basic definitions, rules, and methodologies and describes successful examples of a few drugs developed from snake toxins that are currently used in the clinic for therapy of several diseases as well as new molecular entities in clinical development based on spider-venom-derived peptide toxins.
Doron Steinberg and Michael Friedman. 2020. “Sustained-release delivery of antimicrobial drugs for the treatment of periodontal diseases: Fantasy or already reality?” Periodontology 2000, 84, 1, Pp. 176–187. Abstract
Periodontal diseases are prevalent in humans. Conventional means of combating these diseases involve basic oral hygiene, mostly toothbrushing, use of mouthwashes, and flossing. Supplementary means of treatment, either clinical or pharmaceutical, are often necessary. The use of sustained-release delivery systems, applied locally to the periodontal pocket, seems to be one feasible approach: local sustained-release delivery of antibacterial agents to treat periodontal diseases is conceivable. The use of local (intrapocket) sustained-release delivery systems has numerous clinical, pharmacologic, and toxicologic advantages over conventional treatments for periodontal diseases. Sustained-release technology has been proven to be effective over the last few decades. Films, gels, and fibers are the three main classical intrapocket pharmaceutical delivery systems. Research today is more focused on improving drug delivery, and less on introducing new drugs. New approaches, eg, those making use of nanotechnology, are emerging for local drug-delivery systems. The local sustained-release delivery system concept is innovative and a few products are already commercially available.
Maryam Kartawy, Igor Khaliulin, and Haitham Amal. 2020. “Systems biology reveals reprogramming of the S-nitroso-proteome in the cortical and striatal regions of mice during aging process.” Scientific reports, 10, 1, Pp. 13913. Abstract
Cell aging depends on the rate of cumulative oxidative and nitrosative damage to DNA and proteins. Accumulated data indicate the involvement of protein S-nitrosylation (SNO), the nitric oxide (NO)-mediated posttranslational modification (PTM) of cysteine thiols, in different brain disorders. However, the changes and involvement of SNO in aging including the development of the organism from juvenile to adult state is still unknown. In this study, using the state-of-the-art mass spectrometry technology to identify S-nitrosylated proteins combined with large-scale computational biology, we tested the S-nitroso-proteome in juvenile and adult mice in both cortical and striatal regions. We found reprogramming of the S-nitroso-proteome in adult mice of both cortex and striatum regions. Significant biological processes and protein-protein clusters associated with synaptic and neuronal terms were enriched in adult mice. Extensive quantitative analysis revealed a large set of potentially pathological proteins that were significantly upregulated in adult mice. Our approach, combined with large scale computational biology allowed us to perform a system-level characterization and identification of the key proteins and biological processes that can serve as drug targets for aging and brain disorders in future studies.
Amit Badihi, Marina Frušić-Zlotkin, Yoram Soroka, Sandrine Benhamron, Tomer Tzur, Taher Nassar, and Simon Benita. 2020. “Topical nano-encapsulated cyclosporine formulation for atopic dermatitis treatment.” Nanomedicine : nanotechnology, biology, and medicine, 24, Pp. 102140. Abstract
Systemic cyclosporine A (CsA) therapy shows efficacy in the treatment of recalcitrant severe atopic dermatitis (AD) but elicits severe side-effects. Thus, a topical formulation of CsA nanocapsules (NCs), able to potentially bypass these drawbacks, was developed. CsA-NCs were shown to enhance drug penetration into the various layers of porcine ear skin. Furthermore, the encapsulated CsA was biologically active, as shown in vitro on mouse splenocytes, reflected by inhibition of both cell proliferation and of interleukin (IL)-2 secretion. Ex-vivo efficacy was demonstrated on human skin organ culture by markedly reducing pro-inflammatory cytokines secretion. Finally, CsA-NCs topical formulation elicited improved efficacy in terms of better preservation of the skin barrier integrity, a decrease of the systemic pro-inflammation markers and reduced skin inflammation. The overall results suggest that this original topical platform may provide a novel therapeutic tool of clinical significance compared to the existing topical therapeutic drugs in AD.
Alberto A Gabizon, Rafael TM de Rosales, and Ninh M La-Beck. 2020. “Translational considerations in nanomedicine: The oncology perspective.” Advanced drug delivery reviews, 158, Pp. 140–157. Abstract
Nanoparticles can provide effective control of the release rate and tissue distribution of their drug payload, leading to major pharmacokinetic and pharmacodynamic changes vis-à-vis the conventional administration of free drugs. In the last two decades, we have witnessed major progress in the synthesis and characterization of engineered nanoparticles for imaging and treatment of cancers, resulting in the approval for clinical use of several products and in new and promising approaches. Despite these advances, clinical applications of nanoparticle-based therapeutic and imaging agents remain limited due to biological, immunological, and translational barriers. There is a need to make high impact advances toward translation. In this review, we address biological, toxicological, immunological, and translational aspects of nanomedicine and discuss approaches to move the field forward productively. Overcoming these barriers may dramatically improve the development potential and role of nanomedicines in the oncology field and help meet the high expectations.
Catherine KJ Chen, Peter Kappen, Dan Gibson, and Trevor W Hambley. 2020. “trans-Platinum(iv) pro-drugs that exhibit unusual resistance to reduction by endogenous reductants and blood serum but are rapidly activated inside cells: (1)H NMR and XANES spectroscopy study.” Dalton transactions (Cambridge, England : 2003), 49, 23, Pp. 7722–7736. Abstract
Recent results have confirmed that protection of transplatin from reactions on the path to cancer cells substantially increases their activity, suggesting that such complexes have greater potential than previously thought. In this study we have investigated the use of the platinum(iv) oxidation state and the tetracarboxylate coordination sphere to determine whether these features could impart the same stability to trans-diammineplatinum complexes that they do to cis-diam(m)ineplatinum complexes. The cis complexes exhibit resistance to reduction by l-ascorbate and human blood serum, but are readily reduced inside cancer cells. Studies of reduction monitored by 1H NMR revealed that oxidation of trans-diammineplatinum(ii) complexes does not always result in significant stabilisation, but the complexes trans, trans, trans-[Pt(OAc)4(NH3)2] (OAc = acetate) and trans, trans, trans-[Pt(OPr)2(OAc)2(NH3)2] (OPr = propionate) exhibit second order half-lives of 33 h and 5.9 days respectively in the presence of a ten-fold excess of l-ascorbate. XANES spectroscopy studies of reduction in blood models showed that trans, trans, trans-[Pt(OAc)4(NH3)2] is stable in blood serum for at least 24 hours, but is reduced rapidly in whole blood and was observed to have a half-life of approximately 4 hours in DLD-1 colon cancer cells. Consequently, the tetracarboxylatoplatinum(iv) moiety has the properties required to enable the delivery of trans-diammine platinum complexes to cancer cells.
Dana Ekstein, Iris Noyman, Firas Fahoum, Moshe Herskovitz, Ilan Linder, Bruria Ben Zeev, and Sara Eyal. 2020. “Treating Epilepsy Patients with Investigational Anti-COVID-19 Drugs: Recommendations by the Israeli Chapter of the ILAE.” The Israel Medical Association journal : IMAJ, 11, 22, Pp. 665–672. Abstract
The coronavirus disease-2019 (COVID-19) and its management in patients with epilepsy can be complex. Prescribers should consider potential effects of investigational anti-COVID-19 drugs on seizures, immunomodulation by anti-seizure medications (ASMs), changes in ASM pharmacokinetics, and the potential for drug-drug interactions (DDIs). The goal of the Board of the Israeli League Against Epilepsy (the Israeli Chapter of the International League Against Epilepsy, ILAE) was to summarize the main principles of the pharmacological treatment of COVID-19 in patients with epilepsy. This guide was based on current literature, drug labels, and drug interaction resources. We summarized the available data related to the potential implications of anti-COVID-19 co-medication in patients treated with ASMs. Our recommendations refer to drug selection, dosing, and patient monitoring. Given the limited availability of data, some recommendations are based on general pharmacokinetic or pharmacodynamic principles and might apply to additional future drug combinations as novel treatments emerge. They do not replace evidence-based guidelines, should those become available. Awareness to drug characteristics that increase the risk of interactions can help adjust anti-COVID-19 and ASM treatment for patients with epilepsy.
Jacob Golenser, Nadeen Salaymeh, Abd Alroof Higazi, Mohammed Alyan, Mahran Daif, Ron Dzikowski, and Abraham J Domb. 2020. “Treatment of Experimental Cerebral Malaria by Slow Release of Artemisone From Injectable Pasty Formulation.” Frontiers in pharmacology, 11, Pp. 846. Abstract
Malaria caused by Plasmodium falciparum causes numerous cases of morbidity with about 400,000 deaths yearly owing, mainly, to inflammation leading to cerebral malaria (CM). CM conventionally is treated by repetitive administration of anti-plasmodial drugs and supportive non-specific drugs, for about a week. A mouse model of CM caused by Plasmodium berghei ANKA, in which brain and systemic clinical pathologies occur followed by sudden death within about a week, was used to study the effect of artemisone, a relatively new artemisinin, within an injectable pasty polymer formulated for its controlled release. The parasites were exposed to the drug over several days at a non-toxic concentrations for the mice but high enough to affect the parasites. Artemisone was also tested in cultures of bacteria, cancer cells and P. falciparum to evaluate the specificity and suitability of these cells for examining the release of artemisone from its carrier. Cultures of P. falciparum were the most suitable. Artemisone released from subcutaneous injected poly(sebacic acid-ricinoleic acid) (PSARA) pasty polymer, reduced parasitemias in infected mice, prolonged survival and prevented death in most of the infected mice. Successful prophylactic treatment before infection proved that there was a slow release of the drug for about a week, which contrasts with the three hour half-life that occurs after injection of just the drug. Treatment with artemisone within the polymer, even at a late stage of the disease, helped to prevent or, at least, delay accompanying severe symptoms. In some cases, treatment prevented death of CM and the mice died later of anemia. Postponing the severe clinical symptoms is also beneficial in cases of human malaria, giving more time for an appropriate diagnosis and treatment before severe symptoms appear. The method presented here may also be useful for combination therapy of anti-plasmodial and immunomodulatory drugs.
Yifat Brill-Karniely, Dvir Dror, Tal Duanis-Assaf, Yoel Goldstein, Ouri Schwob, Talya Millo, Natalie Orehov, Tal Stern, Mohammad Jaber, Netanel Loyfer, Margarita Vosk-Artzi, Hadar Benyamini, Diane Bielenberg, Tommy Kaplan, Yosef Buganim, Meital Reches, and Ofra Benny. 2020. “Triangular correlation (TrC) between cancer aggressiveness, cell uptake capability, and cell deformability.” Science advances, 6, 3, Pp. eaax2861. Abstract
The malignancy potential is correlated with the mechanical deformability of the cancer cells. However, mechanical tests for clinical applications are limited. We present here a Triangular Correlation (TrC) between cell deformability, phagocytic capacity, and cancer aggressiveness, suggesting that phagocytic measurements can be a mechanical surrogate marker of malignancy. The TrC was proved in human prostate cancer cells with different malignancy potential, and in human bladder cancer and melanoma cells that were sorted into subpopulations based solely on their phagocytic capacity. The more phagocytic subpopulations showed elevated aggressiveness ex vivo and in vivo. The uptake potential was preserved, and differences in gene expression and in epigenetic signature were detected. In all cases, enhanced phagocytic and aggressiveness phenotypes were correlated with greater cell deformability and predicted by a computational model. Our multidisciplinary study provides the proof of concept that phagocytic measurements can be applied for cancer diagnostics and precision medicine.
Rajamohamed Beema Shafreen, Selvaraj Alagu Lakshmi, Shunmugiah Karutha Pandian, Yong Seo Park, Young Mo Kim, Paweł Paśko, Joseph Deutsch, Elena Katrich, and Shela Gorinstein. 2020. “Unraveling the Antioxidant, Binding and Health-Protecting Properties of Phenolic Compounds of Beers with Main Human Serum Proteins: In Vitro and In Silico Approaches.” Molecules (Basel, Switzerland), 25, 21. Abstract
Our recently published in vivo studies and growing evidence suggest that moderate consumption of beer possesses several health benefits, including antioxidant and cardiovascular effects. Although beer contains phenolic acids and flavonoids as the major composition, and upon consumption, the levels of major components increase in the blood, there is no report on how these beer components interact with main human serum proteins. Thus, to address the interaction potential between beer components and human serum proteins, the present study primarily aims to investigate the components of beer from different industrial sources as well as their mode of interaction through in silico analysis. The contents of the bioactive compounds, antioxidant capacities and their influence on binding properties of the main serum proteins in human metabolism (human serum albumin (HSA), plasma circulation fibrinogen (PCF), C-reactive protein (CRP) and glutathione peroxidase 3 (GPX3)) were studied. In vitro and in silico studies indicated that phenolic substances presented in beer interact with the key regions of the proteins to enhance their antioxidant and health properties. We hypothesize that moderate consumption of beer could be beneficial for patients suffering from coronary artery disease (CAD) and other health advantages by regulating the serum proteins.
Dvora Izgelov, Aviva Regev, Abraham J Domb, and Amnon Hoffman. 2020. “Using the Absorption Cocktail Approach to Assess Differential Absorption Kinetics of Cannabidiol Administered in Lipid-Based Vehicles in Rats.” Molecular pharmaceutics, 17, 6, Pp. 1979–1986. Abstract
Lipid-based drug delivery systems have been vastly investigated as a pharmaceutical method to enhance oral absorption of lipophilic drugs. However, these vehicles not only affect drug bioavailability but may also have an impact on gastric emptying, drug disposition, lymphatic absorption and be affected by lipid digestion mechanisms. The work presented here compared the pharmacokinetic (PK) behavior of the non-intoxicating cannabinoid cannabidiol (CBD) in sesame oil vs. a self-nano emulsifying drug delivery system (SNEDDS). This investigation was conducted with a unique tool termed the "absorption cocktail approach". In this concept, selected molecules: metoprolol, THC, and ibuprofen, were coadministered with CBD in the SNEDDS and sesame oil. This method was used to shed light on the complex absorption process of poorly soluble drugs in vivo, specifically assessing the absorption kinetics of CBD. It was found that the concentration vs. time curve following CBD-sesame oil oral administration showed extended input of the drug with a delayed T(max) compared to CBD-SNEDDS. Using the "cocktail" approach, a unique finding was observed when the less lipophilic compounds (metoprolol and ibuprofen) exited the stomach much earlier than the lipophilic cannabinoids in sesame oil, proving differential absorption kinetics. Findings of the absorption cocktail approach reflected the physiological process of the GI, e.g., gastric retention, stomach content separation, lipid digestion, drug precipitation and more, demonstrating its utility. Nonetheless, the search for more compounds as suitable probes is underway.
Alexey Bingor and Rami Yaka. 2020. “Using Toxins in Brain Slice Recordings.” Methods in molecular biology (Clifton, N.J.), 2068, Pp. 269–274. Abstract
Use of biological toxins from different kinds is widely accepted in electrophysiological experiments. In particular, electrophysiological recordings from brain tissue slices are usually conducted with toxins to manipulate on different receptors or ion channels. Here we describe usage of toxins in electrophysiological experiments in acute brain slices.
Alexey Bingor, Tomer Haham, Claire Thornton, Yael Stern-Bach, and Rami Yaka. 2020. “Zeta Inhibitory Peptide attenuates learning and memory by inducing NO-mediated downregulation of AMPA receptors.” Nature communications, 11, 1, Pp. 3688. Abstract
Zeta inhibitory peptide (ZIP), a PKM$\zeta$ inhibitor, is widely used to interfere with the maintenance of acquired memories. ZIP is able to erase memory even in the absence of PKM$\zeta$, via an unknown mechanism. We found that ZIP induces redistribution of the AMPARGluA1 in HEK293 cells and primary cortical neurons, and decreases AMPAR-mediated currents in the nucleus accumbens (NAc). These effects were mimicked by free arginine or by a modified ZIP in which all but the arginine residues were replaced by alanine. Redistribution was blocked by a peptidase-resistant version of ZIP and by treatment with the nitric oxide (NO)-synthase inhibitor L-NAME. ZIP increased GluA1-S831 phosphorylation and ZIP-induced redistribution was blocked by nitrosyl-mutant GluA1-C875S or serine-mutant GluA1-S831A. Introducing the cleavable arginine-alanine peptide into the NAc attenuated expression of cocaine-conditioned reward. Together, these results suggest that ZIP may act as an arginine donor, facilitating NO-dependent downregulation of AMPARs, thereby attenuating learning and memory.
Emiliano Cohen, Rakesh Kumar, Tal Zinger, Avi Priel, and Millet Treinin. 2019. “GTL-1, a Calcium Activated TRPM Channel, Enhances Nociception.” Frontiers in pharmacology, 10, Pp. 1567. Abstract
C. elegans PVD neurons are conserved for morphology, function and molecular determinants with mammalian polymodal nociceptors. Functions of polymodal nociceptors require activities of multiple ion channels and receptors including members of the TRP family. GTL-1, a member of the TRPM subclass of TRP channels, was previously shown to amplify PVD-mediated responses to optogenetic stimuli. Here we characterize effects of GTL-1 on PVD-mediated behavioral responses to noxious stimuli. We show that GTL-1 is required within PVD for the immediate and enduring response to thermal (cold) stimuli. But, find no significant reduction in percent animals responding to single or to repeated noxious mechanical stimuli. Nevertheless, PVD specific knockdown of gtl-1expression reduces the magnitude of responses to noxious mechanical stimuli. To understand GTL-1's mechanism of action we expressed it in HEK293 cells. Our results show GTL-1-dependent currents induced by activation of a G$\alpha$q-coupled Designer Receptor Exclusively Activated by Designer Drugs (DREADD). In addition, using excised patches we show that GTL-1 can be activated by internal calcium. Our results are consistent with indirect, calcium dependent, activation of GTL-1 by noxious stimuli. This mechanism explains the GTL-1-dependent amplification of responses to multiple stimuli optogenetic and sensory in PVD.