scholarly journals Ligand-induced activation of human TRPM2 requires the terminal ribose of ADPR and involves Arg1433 and Tyr1349

2017 ◽  
Vol 474 (13) ◽  
pp. 2159-2175 ◽  
Author(s):  
Ralf Fliegert ◽  
Joanna M. Watt ◽  
Anja Schöbel ◽  
Monika D. Rozewitz ◽  
Christelle Moreau ◽  
...  

TRPM2 (transient receptor potential channel, subfamily melastatin, member 2) is a Ca2+-permeable non-selective cation channel activated by the binding of adenosine 5′-diphosphoribose (ADPR) to its cytoplasmic NUDT9H domain (NUDT9 homology domain). Activation of TRPM2 by ADPR downstream of oxidative stress has been implicated in the pathogenesis of many human diseases, rendering TRPM2 an attractive novel target for pharmacological intervention. However, the structural basis underlying this activation is largely unknown. Since ADP (adenosine 5′-diphosphate) alone did not activate or antagonize the channel, we used a chemical biology approach employing synthetic analogues to focus on the role of the ADPR terminal ribose. All novel ADPR derivatives modified in the terminal ribose, including that with the seemingly minor change of methylating the anomeric-OH, abolished agonist activity at TRPM2. Antagonist activity improved as the terminal substituent increasingly resembled the natural ribose, indicating that gating by ADPR might require specific interactions between hydroxyl groups of the terminal ribose and the NUDT9H domain. By mutating amino acid residues of the NUDT9H domain, predicted by modelling and docking to interact with the terminal ribose, we demonstrate that abrogating hydrogen bonding of the amino acids Arg1433 and Tyr1349 interferes with activation of the channel by ADPR. Taken together, using the complementary experimental approaches of chemical modification of the ligand and site-directed mutagenesis of TRPM2, we demonstrate that channel activation critically depends on hydrogen bonding of Arg1433 and Tyr1349 with the terminal ribose. Our findings allow for a more rational design of novel TRPM2 antagonists that may ultimately lead to compounds of therapeutic potential.

eLife ◽  
2020 ◽  
Vol 9 ◽  
Author(s):  
Yonghong Bai ◽  
Xinchao Yu ◽  
Hao Chen ◽  
Daniel Horne ◽  
Ryan White ◽  
...  

Transient receptor potential canonical (TRPC) proteins form nonselective cation channels that play physiological roles in a wide variety of cells. Despite growing evidence supporting the therapeutic potential of TRPC6 inhibition in treating pathological cardiac and renal conditions, mechanistic understanding of TRPC6 function and modulation remains obscure. Here we report cryo-EM structures of TRPC6 in both antagonist-bound and agonist-bound states. The structures reveal two novel recognition sites for the small-molecule modulators corroborated by mutagenesis data. The antagonist binds to a cytoplasm-facing pocket formed by S1-S4 and the TRP helix, whereas the agonist wedges at the subunit interface between S6 and the pore helix. Conformational changes upon ligand binding illuminate a mechanistic rationale for understanding TRPC6 modulation. Furthermore, structural and mutagenesis analyses suggest several disease-related mutations enhance channel activity by disrupting interfacial interactions. Our results provide principles of drug action that may facilitate future design of small molecules to ameliorate TRPC6-mediated diseases.


Blood ◽  
2006 ◽  
Vol 108 (11) ◽  
pp. 1629-1629
Author(s):  
Vania T. Hinkovska-Galcheva ◽  
Andrea J. Clark ◽  
Andrei L. Kindzelskii ◽  
Susan M. VanWay ◽  
JiBiao Huang ◽  
...  

Abstract We showed that ceramide-1-phosphate (C1P) is formed by ceramide kinase (CERK). In this study the mechanism by which C1P enhanced phagocytosis and phagolysosomal formation in COS-1 cells expressing hCERK was evaluated. We hypothesized that CERK has a unique role in inducing Ca2+ signaling during Fc-mediated phagocytosis via its generation of C1P. Furthermore, we also hypothesize that CERK mediated changes in Ca2+ levels were not direct but required the participation of a store operated channels (SOC). In some systems, evidence suggests that SOC might be related to transient receptor potential channel (TRP) homologues. This hypothesis was tested using cell lines with different levels of expression of CERK and by using series of pharmacological inhibitors. To monitor subcellular localization of hCERK, red fluorescent protein (RFP)-tagged hCERK was created and confocal microscopy was performed. To study dynamic changes in Ca2+ during phagocytosis, imaging microscopy was used. Phagolysosome formation was evaluated by labeling the cells with lysotracker red DND-99 at 37oC and followed by imaging. When challenged with EIgG, hCERK transfected cells increased phagocytosis and simultaneously increased C1P. During subcellular fractionation of hCERK transfected cells, CERK translocates during activation from the cytosol to a lipid raft fraction. We also observed that TRP-1 accumulated at the site of CERK translocation in lipid rafts. Microfluorimetry of indo-1 revealed that Ca2+ oscillations in COS-1 cells, stably transfected with Fcγ RIIA/hCERK, were much higher compared to Fcγ RIIA transfected cells. The enhanced Ca2+ signals were accompanied by enhanced phagolysosome formation. hCERK transfected cells had a mean rate of fusion of 90%, compare to 76% ( catalytic inactive mutant of CERK-G198DhCERK), 65% (Fcγ RIIA), and 70% (Vector) transfected cells. The indo-1 intensity spikes demonstrated significantly higher Ca2+ intensities for phagosomes associated with the hCERK transfectants. The SOC inhibitor SKF96365 blocked enhanced Ca2+ signaling in the hCERK transfected cells. Similarly SOC inhibitors reduced the phagocytic index and phagolysosomal fusion in hCERK transfected cells. Our data showed that there is a co-localization of EIgG and CERK as well as caveolin-1 and CERK on the surface of the phagocytic cells. Site directed mutagenesis demonstrated that the kinase activity of hCERK was required for higher Ca2+ signals. Pharmacological inhibitors revealed that this Ca2+ signal operates through SOC. Our results show that introduction of the hCERK gene in cells alters the functional behavior of intracellular signals and supports the role of C1P in promoting membrane fusion by modulating Ca2+ signaling through activation of SOC


Cells ◽  
2021 ◽  
Vol 10 (1) ◽  
pp. 147
Author(s):  
Yu Fu ◽  
Peng Shang ◽  
Bo Zhang ◽  
Xiaolong Tian ◽  
Ruixue Nie ◽  
...  

In animals, muscle growth is a quantitative trait controlled by multiple genes. Previously, we showed that the transient receptor potential channel 1 (TRPC1) gene was differentially expressed in muscle tissues between pig breeds with divergent growth traits base on RNA-seq. Here, we characterized TRPC1 expression profiles in different tissues and pig breeds and showed that TRPC1 was highly expressed in the muscle. We found two single nucleotide polymorphisms (SNPs) (C-1763T and C-1604T) in TRPC1 that could affect the promoter region activity and regulate pig growth rate. Functionally, we used RNAi and overexpression to illustrate that TRPC1 promotes myoblast proliferation, migration, differentiation, fusion, and muscle hypertrophy while inhibiting muscle degradation. These processes may be mediated by the activation of Wnt signaling pathways. Altogether, our results revealed that TRPC1 might promote muscle growth and development and plays a key role in Wnt-mediated myogenesis.


2021 ◽  
Vol 22 (4) ◽  
pp. 1863
Author(s):  
Philippe A. Melas ◽  
Maria Scherma ◽  
Walter Fratta ◽  
Carlo Cifani ◽  
Paola Fadda

Cannabidiol (CBD) is the most abundant non-psychoactive component of cannabis; it displays a very low affinity for cannabinoid receptors, facilitates endocannabinoid signaling by inhibiting the hydrolysis of anandamide, and stimulates both transient receptor potential vanilloid 1 and 2 and serotonin type 1A receptors. Since CBD interacts with a wide variety of molecular targets in the brain, its therapeutic potential has been investigated in a number of neuropsychiatric diseases, including anxiety and mood disorders. Specifically, CBD has received growing attention due to its anxiolytic and antidepressant properties. As a consequence, and given its safety profile, CBD is considered a promising new agent in the treatment of anxiety and mood disorders. However, the exact molecular mechanism of action of CBD still remains unknown. In the present preclinical review, we provide a summary of animal-based studies that support the use of CBD as an anxiolytic- and antidepressant-like compound. Next, we describe neuropharmacological evidence that links the molecular pharmacology of CBD to its behavioral effects. Finally, by taking into consideration the effects of CBD on DNA methylation, histone modifications, and microRNAs, we elaborate on the putative role of epigenetic mechanisms in mediating CBD’s therapeutic outcomes.


2002 ◽  
Vol 92 (4) ◽  
pp. 1594-1602 ◽  
Author(s):  
Michele Sweeney ◽  
Sharon S. McDaniel ◽  
Oleksandr Platoshyn ◽  
Shen Zhang ◽  
Ying Yu ◽  
...  

Asthma is characterized by airway inflammation, bronchial hyperresponsiveness, and airway obstruction by bronchospasm and bronchial wall thickening due to smooth muscle hypertrophy. A rise in cytosolic free Ca2+ concentration ([Ca2+]cyt) may serve as a shared signal transduction element that causes bronchial constriction and bronchial wall thickening in asthma. In this study, we examined whether capacitative Ca2+ entry (CCE) induced by depletion of intracellular Ca2+ stores was involved in agonist-mediated bronchial constriction and bronchial smooth muscle cell (BSMC) proliferation. In isolated bronchial rings, acetylcholine (ACh) induced a transient contraction in the absence of extracellular Ca2+ because of Ca2+ release from intracellular Ca2+ stores. Restoration of extracellular Ca2+in the presence of atropine, an M-receptor blocker, induced a further contraction that was apparently caused by a rise in [Ca2+]cyt due to CCE. In single BSMC, amplitudes of the store depletion-activated currents ( I SOC) and CCE were both enhanced when the cells proliferate, whereas chelation of extracellular Ca2+ with EGTA significantly inhibited the cell growth in the presence of serum. Furthermore, the mRNA expression of TRPC1, a transient receptor potential channel gene, was much greater in proliferating BSMC than in growth-arrested cells. Blockade of the store-operated Ca2+channels by Ni2+ decreased I SOC and CCE and markedly attenuated BSMC proliferation. These results suggest that upregulated TRPC1 expression, increased I SOC, enhanced CCE, and elevated [Ca2+]cyt may play important roles in mediating bronchial constriction and BSMC proliferation.


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