scholarly journals Distinct properties of Ca2+–calmodulin binding to N- and C-terminal regulatory regions of the TRPV1 channel

2012 ◽  
Vol 140 (5) ◽  
pp. 541-555 ◽  
Author(s):  
Sze-Yi Lau ◽  
Erik Procko ◽  
Rachelle Gaudet
Keyword(s):  
Binding Site ◽  
Transient Receptor Potential ◽  
Receptor Potential ◽  
Feedback Mechanism ◽  
Sequence Motif ◽  
Recognition Sequence ◽  
Calmodulin Binding ◽  
Negative Feedback Mechanism ◽  
C Terminus ◽  
Wide Range

Transient receptor potential (TRP) vanilloid 1 (TRPV1) is a molecular pain receptor belonging to the TRP superfamily of nonselective cation channels. As a polymodal receptor, TRPV1 responds to heat and a wide range of chemical stimuli. The influx of calcium after channel activation serves as a negative feedback mechanism leading to TRPV1 desensitization. The cellular calcium sensor calmodulin (CaM) likely participates in the desensitization of TRPV1. Two CaM-binding sites are identified in TRPV1: the N-terminal ankyrin repeat domain (ARD) and a short distal C-terminal (CT) segment. Here, we present the crystal structure of calcium-bound CaM (Ca2+–CaM) in complex with the TRPV1-CT segment, determined to 1.95-Å resolution. The two lobes of Ca2+–CaM wrap around a helical TRPV1-CT segment in an antiparallel orientation, and two hydrophobic anchors, W787 and L796, contact the C-lobe and N-lobe of Ca2+–CaM, respectively. This structure is similar to canonical Ca2+–CaM-peptide complexes, although TRPV1 contains no classical CaM recognition sequence motif. Using structural and mutational studies, we established the TRPV1 C terminus as a high affinity Ca2+–CaM-binding site in both the isolated TRPV1 C terminus and in full-length TRPV1. Although a ternary complex of CaM, TRPV1-ARD, and TRPV1-CT had previously been postulated, we found no biochemical evidence of such a complex. In electrophysiology studies, mutation of the Ca2+–CaM-binding site on TRPV1-ARD abolished desensitization in response to repeated application of capsaicin, whereas mutation of the Ca2+–CaM-binding site in TRPV1-CT led to a more subtle phenotype of slowed and reduced TRPV1 desensitization. In summary, our results show that the TRPV1-ARD is an important mediator of TRPV1 desensitization, whereas TRPV1-CT has higher affinity for CaM and is likely involved in separate regulatory mechanisms.

scholarly journals Functional basis for calmodulation of the TRPV5 calcium channel

2021 ◽  
Author(s):  
Sara R Roig ◽  
Niky Thijssen ◽  
Merijn van Erp ◽  
Jack Fransen ◽  
Joost G Hoenderop ◽  
...  
Keyword(s):  
Single Molecule ◽  
Transient Receptor Potential ◽  
Receptor Potential ◽  
Feedback Mechanism ◽  
Negative Feedback Mechanism ◽  
Biochemical Assays ◽  
Selective Channel ◽  
Cam Regulation ◽  
Transient Receptor ◽  
Microscopy Techniques

AbstractWithin the transient receptor potential (TRP) superfamily of ion channels, TRPV5 is a highly Ca2+-selective channel important for active reabsorption of Ca2+ in the kidney. Its channel activity is controlled by a negative feedback mechanism involving calmodulin (CaM) binding. Combining advanced microscopy techniques and biochemical assays, this study characterized the dynamic bilobal CaM regulation and binding stoichiometry. We demonstrate for the first time that functional (full-length) TRPV5 interacts with CaM in the absence of Ca2+, and this interaction is intensified at increasing Ca2+ concentrations sensed by the CaM C-lobe that achieves channel pore blocking. Channel inactivation occurs without CaM N-lobe calcification. Moreover, we reveal a 1:2 stoichiometry of TRPV5:CaM binding by implementing single molecule photobleaching counting, a technique with great potential for studying TRP channel regulation. In conclusion, our study proposes a new model for CaM- dependent regulation – calmodulation – of the Ca2+-selective TRPV5 that involves apoCaM interaction and lobe-specific actions.

scholarly journals The transient receptor potential, TRP4, cation channel is a novel member of the family of calmodulin binding proteins

2001 ◽  
Vol 355 (3) ◽  
pp. 663-670 ◽  
Author(s):  
Claudia TROST ◽  
Christiane BERGS ◽  
Nina HIMMERKUS ◽  
Veit FLOCKERZI
Keyword(s):  
Amino Acid ◽  
Ion Channels ◽  
Transient Receptor Potential ◽  
Direct Interaction ◽  
Receptor Potential ◽  
Amino Acid Residues ◽  
Glutathione S Transferase ◽  
Calmodulin Binding ◽  
Transient Receptor

The mammalian gene products, transient receptor potential (trp)1 to trp7, are related to the Drosophila TRP and TRP-like ion channels, and are candidate proteins underlying agonist-activated Ca2+-permeable ion channels. Recently, the TRP4 protein has been shown to be part of native store-operated Ca2+-permeable channels. These channels, most likely, are composed of other proteins in addition to TRP4. In the present paper we report the direct interaction of TRP4 and calmodulin (CaM) by: (1) retention of in vitro translated TRP4 and of TRP4 protein solubilized from bovine adrenal cortex by CaM–Sepharose in the presence of Ca2+, and (2) TRP4–glutathione S-transferase pull-down experiments. Two domains of TRP4, amino acid residues 688–759 and 786–848, were identified as being able to interact with CaM. The binding of CaM to both domains occurred only in the presence of Ca2+ concentrations above 10µM, with half maximal binding occurring at 16.6µM (domain 1) and 27.9µM Ca2+ (domain 2). Synthetic peptides, encompassing the two putative CaM binding sites within these domains and covering amino acid residues 694–728 and 829–853, interacted directly with dansyl–CaM with apparent Kd values of 94–189nM. These results indicate that TRP4/Ca2+-CaM are parts of a signalling complex involved in agonist-induced Ca2+ entry.

scholarly journals The Pivotal Role of TRP Channels in Homeostasis and Diseases throughout the Gastrointestinal Tract

2019 ◽  
Vol 20 (21) ◽  
pp. 5277 ◽  
Author(s):  
Alessandro Alaimo ◽  
Josep Rubert
Keyword(s):  
Drug Targets ◽  
Transient Receptor Potential ◽  
Trp Channels ◽  
Receptor Potential ◽  
Taste Perception ◽  
Gi Tract ◽  
Visceral Hyperalgesia ◽  
Altered Expression ◽  
Wide Range ◽  
Trp Genes

The transient receptor potential (TRP) channels superfamily are a large group of proteins that play crucial roles in cellular processes. For example, these cation channels act as sensors in the detection and transduction of stimuli of temperature, small molecules, voltage, pH, and mechanical constrains. Over the past decades, different members of the TRP channels have been identified in the human gastrointestinal (GI) tract playing multiple modulatory roles. Noteworthy, TRPs support critical functions related to the taste perception, mechanosensation, and pain. They also participate in the modulation of motility and secretions of the human gut. Last but not least, altered expression or activity and mutations in the TRP genes are often related to a wide range of disorders of the gut epithelium, including inflammatory bowel disease, fibrosis, visceral hyperalgesia, irritable bowel syndrome, and colorectal cancer. TRP channels could therefore be promising drug targets for the treatment of GI malignancies. This review aims at providing a comprehensive picture of the most recent advances highlighting the expression and function of TRP channels in the GI tract, and secondly, the description of the potential roles of TRPs in relevant disorders is discussed reporting our standpoint on GI tract–TRP channels interactions.

scholarly journals NGF Enhances CGRP Release Evoked by Capsaicin from Rat Trigeminal Neurons: Differential Inhibition by SNAP-25-Cleaving Proteases

2022 ◽  
Vol 23 (2) ◽  
pp. 892
Author(s):  
Mariia Belinskaia ◽  
Tomas Zurawski ◽  
Seshu Kumar Kaza ◽  
Caren Antoniazzi ◽  
J. Oliver Dolly ◽  
...  
Keyword(s):  
Transient Receptor Potential ◽  
Receptor Potential ◽  
Sensory Nerves ◽  
Neonatal Rat ◽  
Transient Receptor Potential Vanilloid ◽  
C Terminus ◽  
Low Concentrations ◽  
Transient Receptor ◽  
Neuronal Functions ◽  
Differential Ability

Nerve growth factor (NGF) is known to intensify pain in various ways, so perturbing pertinent effects without negating its essential influences on neuronal functions could help the search for much-needed analgesics. Towards this goal, cultured neurons from neonatal rat trigeminal ganglia—a locus for craniofacial sensory nerves—were used to examine how NGF affects the Ca2+-dependent release of a pain mediator, calcitonin gene-related peptide (CGRP), that is triggered by activating a key signal transducer, transient receptor potential vanilloid 1 (TRPV1) with capsaicin (CAP). Measurements utilised neurons fed with or deprived of NGF for 2 days. Acute re-introduction of NGF induced Ca2+-dependent CGRP exocytosis that was inhibited by botulinum neurotoxin type A (BoNT/A) or a chimera of/E and/A (/EA), which truncated SNAP-25 (synaptosomal-associated protein with Mr = 25 k) at distinct sites. NGF additionally caused a Ca2+-independent enhancement of the neuropeptide release evoked by low concentrations (<100 nM) of CAP, but only marginally increased the peak response to ≥100 nM. Notably, BoNT/A inhibited CGRP exocytosis evoked by low but not high CAP concentrations, whereas/EA effectively reduced responses up to 1 µM CAP and inhibited to a greater extent its enhancement by NGF. In addition to establishing that sensitisation of sensory neurons to CAP by NGF is dependent on SNARE-mediated membrane fusion, insights were gleaned into the differential ability of two regions in the C-terminus of SNAP-25 (181–197 and 198–206) to support CAP-evoked Ca2+-dependent exocytosis at different intensities of stimulation.

scholarly journals Differential epitope masking reveals synapse-specific complexes of TRPM1

2018 ◽  
Vol 35 ◽  
Author(s):  
MELINA A. AGOSTO ◽  
IVAN A. ANASTASSOV ◽  
THEODORE G. WENSEL
Keyword(s):  
Binding Site ◽  
Transient Receptor Potential ◽  
Transmembrane Domain ◽  
Receptor Potential ◽  
Transient Receptor Potential Channel ◽  
Bipolar Cells ◽  
Mouse Retina ◽  
Binding Partners ◽  
Transient Receptor ◽  
Quantitative Immunoblotting

AbstractThe transient receptor potential channel TRPM1 is required for synaptic transmission between photoreceptors and the ON subtype of bipolar cells (ON-BPC), mediating depolarization in response to light. TRPM1 is present in the somas and postsynaptic dendritic tips of ON-BPCs. Monoclonal antibodies generated against full-length TRPM1 were found to have differential labeling patterns when used to immunostain the mouse retina, with some yielding reduced labeling of dendritic tips relative to the labeling of cell bodies. Epitope mapping revealed that those antibodies that poorly label the dendritic tips share a binding site (N2d) in the N-terminal arm near the transmembrane domain. A major splice variant of TRPM1 lacking exon 19 does not contain the N2d binding site, but quantitative immunoblotting revealed no enrichment of this variant in synaptsomes. One explanation of the differential labeling is masking of the N2d epitope by formation of a synapse-specific multiprotein complex. Identifying the binding partners that are specific for the fraction of TRPM1 present at the synapses is an ongoing challenge for understanding TRPM1 function.

scholarly journals The human polycystin-2 protein represents an integral membrane protein with six membrane-spanning domains and intracellular N- and C-termini

2010 ◽  
Vol 433 (2) ◽  
pp. 285-294 ◽  
Author(s):  
Helen Hoffmeister ◽  
Anna-Rachel Gallagher ◽  
Anne Rascle ◽  
Ralph Witzgall
Keyword(s):  
Endoplasmic Reticulum ◽  
Experimental Evidence ◽  
Transient Receptor Potential ◽  
Receptor Potential ◽  
Integral Membrane Protein ◽  
Protein Product ◽  
C Terminus ◽  
Autosomal Dominant Polycystic Kidney ◽  
Transient Receptor ◽  
Membrane Spanning

PKD2 is one of the two genes mutated in ADPKD (autosomal-dominant polycystic kidney disease). The protein product of PKD2, polycystin-2, functions as a non-selective cation channel in the endoplasmic reticulum and possibly at the plasma membrane. Hydrophobicity plots and its assignment to the TRP (transient receptor potential) family of cation channels suggest that polycystin-2 contains six transmembrane domains and that both the N- and C-termini extend into the cytoplasm. However, no experimental evidence for this model has so far been provided. To determine the orientation of the different loops of polycystin-2, we truncated polycystin-2 within the predicted loops 1–5 and tagged the constructs at the C-terminus with an HA (haemagglutinin) epitope. After transient expression and selective membrane permeabilization, immunofluorescence staining for the HA epitope revealed that loops 1, 3 and 5 extend into the lumen of the endoplasmic reticulum or the extracellular space, whereas loops 2 and 4 extend into the cytoplasm. This approach also confirmed the cytoplasmic orientation of the N- and C-termini of polycystin-2. In accordance with the immunofluorescence data, protease protection assays from microsomal preparations yielded protected fragments when polycystin-2 was truncated in loops 1, 3 and 5, whereas no protected fragments could be detected when polycystin-2 was truncated in loops 2 and 4. The results of the present study therefore provide the first experimental evidence for the topological orientation of polycystin-2.

scholarly journals TRP Receptors in Arthritis, Gaining Knowledge for Translation from Experimental Models

2013 ◽  
Vol 6 (1) ◽  
pp. 50-61 ◽  
Author(s):  
E.S. Fernandes ◽  
S. Awal ◽  
R. Karadaghi ◽  
S.D. Brain
Keyword(s):  
Transient Receptor Potential ◽  
Trp Channels ◽  
Receptor Potential ◽  
Transient Receptor Potential Vanilloid ◽  
Joint Movement ◽  
New Findings ◽  
Wide Range ◽  
Clinical Models ◽  
Transient Receptor ◽  
Trp Receptors

Arthritis is a condition characterised by mainly pain, reduced joint movement and signs of inflammation, such as swelling. The disorder has many different types, of which osteoarthritis (a degenerative joint disease) and rheumatoid arthritis (a chronic autoimmune disease) are the two most common forms. There are >6 million sufferers in the UK and both conditions have a huge potential to impair capabilities and contribute to social and economic burdens. Whilst there are a wide range of arthritic therapies available, many patients under treatment complain of poor pain relief. Thus there is a need for novel therapeutic approaches, and the transient receptor potential (TRP) family of receptor channels has been investigated. One particular area of recent research has been the ligand-gated transient receptor potential vanilloid 1 (TRPV1) channel. Findings from numerous pre-clinical models and scientific studies have shown that TRPV1 desensitisation, or the use of TRPV1 antagonists alleviates pain and some inflammatory aspects. New findings have started to unveil the potential of other TRP channels in mediating arthritic pain and inflammation. With the understanding that the currently available treatments for arthritis are limited, researchers have looked into the exciting prospect that TRP receptor antagonists may be developed into effective, specific drugs, which would potentially protect against the complications of arthritis. These antagonists are still under development, although only data from studies from pre-clinical models are currently available. This review acts to summarize knowledge of the potential influence of TRP receptors in arthritis to date.

scholarly journals Molecular Basis of TRPA1 Regulation in Nociceptive Neurons. A Review

2017 ◽  
pp. 425-439 ◽  
Author(s):  
A. KÁDKOVÁ ◽  
V. SYNYTSYA ◽  
J. KRUSEK ◽  
L. ZÍMOVÁ ◽  
V. VLACHOVÁ
Keyword(s):  
Molecular Basis ◽  
Transient Receptor Potential ◽  
Current Knowledge ◽  
Sensory Nerve ◽  
Receptor Potential ◽  
Nociceptive Response ◽  
Nociceptive Neurons ◽  
Physiological Relevance ◽  
Wide Range ◽  
Transient Receptor

Transient receptor potential A1 (TRPA1) is an excitatory ion channel that functions as a cellular sensor, detecting a wide range of proalgesic agents such as environmental irritants and endogenous products of inflammation and oxidative stress. Topical application of TRPA1 agonists produces an acute nociceptive response through peripheral release of neuropeptides, purines and other transmitters from activated sensory nerve endings. This, in turn, further regulates TRPA1 activity downstream of G-protein and phospholipase C-coupled signaling cascades. Despite the important physiological relevance of such regulation leading to nociceptor sensitization and consequent pain hypersensitivity, the specific domains through which TRPA1 undergoes post-translational modifications that affect its activation properties are yet to be determined at a molecular level. This review aims at providing an account of our current knowledge on molecular basis of regulation by neuronal inflammatory signaling pathways that converge on the TRPA1 channel protein and through modification of its specific residues influence the extent to which this channel may contribute to pain.

scholarly journals Molecular mapping of transmembrane mechanotransduction through the β1 integrin–CD98hc–TRPV4 axis

2020 ◽  
Vol 133 (20) ◽  
pp. jcs248823 ◽  
Author(s):  
Ratnakar Potla ◽  
Mariko Hirano-Kobayashi ◽  
Hao Wu ◽  
Hong Chen ◽  
Akiko Mammoto ◽  
...  
Keyword(s):  
Transient Receptor Potential ◽  
Molecular Mapping ◽  
Calcium Influx ◽  
Focal Adhesions ◽  
Receptor Potential ◽  
Transient Receptor Potential Vanilloid ◽  
Β1 Integrin ◽  
Mechanical Forces ◽  
C Terminus ◽  
Transient Receptor

ABSTRACTOne of the most rapid (less than 4 ms) transmembrane cellular mechanotransduction events involves activation of transient receptor potential vanilloid 4 (TRPV4) ion channels by mechanical forces transmitted across cell surface β1 integrin receptors on endothelial cells, and the transmembrane solute carrier family 3 member 2 (herein denoted CD98hc, also known as SLC3A2) protein has been implicated in this response. Here, we show that β1 integrin, CD98hc and TRPV4 all tightly associate and colocalize in focal adhesions where mechanochemical conversion takes place. CD98hc knockdown inhibits TRPV4-mediated calcium influx induced by mechanical forces, but not by chemical activators, thus confirming the mechanospecificity of this signaling response. Molecular analysis reveals that forces applied to β1 integrin must be transmitted from its cytoplasmic C terminus via the CD98hc cytoplasmic tail to the ankyrin repeat domain of TRPV4 in order to produce ultrarapid, force-induced channel activation within the focal adhesion.

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