scholarly journals Structure and selectivity engineering of the M1 muscarinic receptor toxin complex

Science ◽  
2020 ◽  
Vol 369 (6500) ◽  
pp. 161-167 ◽  
Author(s):  
Shoji Maeda ◽  
Jun Xu ◽  
Francois Marie N. Kadji ◽  
Mary J. Clark ◽  
Jiawei Zhao ◽  
...  
Keyword(s):  
Acetylcholine Receptors ◽  
Muscarinic Acetylcholine Receptors ◽  
Tertiary Structures ◽  
Venom Toxin ◽  
Natural Toxins ◽  
Subtype Specificity ◽  
Snake Venom Toxin ◽  
M1 Muscarinic ◽  
Subtype Selective

Muscarinic toxins (MTs) are natural toxins produced by mamba snakes that primarily bind to muscarinic acetylcholine receptors (MAChRs) and modulate their function. Despite their similar primary and tertiary structures, MTs show distinct binding selectivity toward different MAChRs. The molecular details of how MTs distinguish MAChRs are not well understood. Here, we present the crystal structure of M1AChR in complex with MT7, a subtype-selective anti-M1AChR snake venom toxin. The structure reveals the molecular basis of the extreme subtype specificity of MT7 for M1AChR and the mechanism by which it regulates receptor function. Through in vitro engineering of MT7 finger regions that was guided by the structure, we have converted the selectivity from M1AChR toward M2AChR, suggesting that the three-finger fold is a promising scaffold for developing G protein–coupled receptor modulators.

scholarly journals Preparation of a First 18F-Labeled Agonist for M1 Muscarinic Acetylcholine Receptors

Molecules ◽  
2020 ◽  
Vol 25 (12) ◽  
pp. 2880 ◽  
Author(s):  
Boris D. Zlatopolskiy ◽  
Felix Neumaier ◽  
Till Rüngeler ◽  
Birte Drewes ◽  
Niklas Kolks ◽  
...  
Keyword(s):  
Acetylcholine Receptors ◽  
Radiochemical Yield ◽  
Muscarinic Acetylcholine Receptors ◽  
Preparative Scale ◽  
Muscarinic Acetylcholine ◽  
Pet Tracer ◽  
Positron Emission ◽  
Diagnostic Applications ◽  
M1 Muscarinic ◽  
Subtype Selective

M1 muscarinic acetylcholine receptors (mAChRs) are abundant in postsynaptic nerve terminals of all forebrain regions and have been implicated in the cognitive decline associated with Alzheimer’s disease and other CNS pathologies. Consequently, major efforts have been spent in the development of subtype-selective positron emission tomography (PET) tracers for mAChRs resulting in the development of several 11C-labeled probes. However, protocols for the preparation of 18F-labeled mAChR-ligands have not been published so far. Here, we describe a straightforward procedure for the preparation of an 18F-labeled M1 mAChR agonist and its corresponding pinacol boronate radiolabeling precursor and the non-radioactive reference compound. The target compounds were prepared from commercially available aryl fluorides and Boc protected 4-aminopiperidine using a convergent reaction protocol. The radiolabeling precursor was prepared by a modification of the Miyaura reaction and labeled via the alcohol-enhanced Cu-mediated radiofluorination. The developed procedure afforded the radiotracer in a non-decay-corrected radiochemical yield of 17 ± 3% (n = 3) and in excellent radiochemical purity (>99%) on a preparative scale. Taken together, we developed a straightforward protocol for the preparation of an 18F-labeled M1 mAChR agonist that is amenable for automation and thus provides an important step towards the routine production of a 18F-labeled M1 selective PET tracer for experimental and diagnostic applications.

scholarly journals Expression of the collagen receptor glycoprotein VI during megakaryocyte differentiation

Blood ◽  
2000 ◽  
Vol 96 (8) ◽  
pp. 2740-2745 ◽  
Author(s):  
Oscar Berlanga ◽  
Regis Bobe ◽  
Marion Becker ◽  
George Murphy ◽  
Mireille Leduc ◽  
...  
Keyword(s):  
Cell Lines ◽  
Chain Reaction ◽  
Activated T Cells ◽  
Glycoprotein Vi ◽  
Venom Toxin ◽  
Hel Cells ◽  
Snake Venom Toxin ◽  
Polymerase Chain ◽  
Collagen Receptor

Abstract This study examined the expression of the platelet collagen receptor glycoprotein VI (GPVI) in megakaryocyte cell lines and primary megakaryocytes by reverse transcriptase-polymerase chain reaction and by flow cytometry and ligand blotting using the snake venom toxin convulxin. Expression of GPVI is increased in the megakaryoblastic cell lines HEL and CMK on differentiation with the phorbol ester phorbol 12-myristate 13-acetate (PMA), along with the Fc receptor γ-chain (FcR γ-chain). The increase in GPVI expression is associated with marked potentiation of tyrosine phosphorylation and Ca++ elevation in response to convulxin. Syk, linker for activated T cells, and phospholipase Cγ2 (PLCγ2) are among the proteins tyrosine phosphorylated on convulxin stimulation in PMA-differentiated HEL cells. Studies on primary murine megakaryocytes grown in vitro confirmed that GPVI is up-regulated in parallel with functional activation, assessed by measurement of [Ca++]i, during differentiation. The results demonstrate that expression of GPVI is up-regulated along with the FcR γ-chain during differentiation of megakaryocytes.

scholarly journals Presynaptic cholinergic neuromodulation alters the temporal dynamics of short-term depression at parvalbumin-positive basket cell synapses from juvenile CA1 mouse hippocampus

2015 ◽  
Vol 113 (7) ◽  
pp. 2408-2419 ◽  
Author(s):  
J. Josh Lawrence ◽  
Heikki Haario ◽  
Emily F. Stone
Keyword(s):  
Pyramidal Cell ◽  
Acetylcholine Receptors ◽  
Temporal Dynamics ◽  
Hippocampal Slices ◽  
Pyramidal Cells ◽  
Calcium Transient ◽  
Muscarinic Acetylcholine Receptors ◽  
Presynaptic Calcium

Parvalbumin-positive basket cells (PV BCs) of the CA1 hippocampus are active participants in theta (5–12 Hz) and gamma (20–80 Hz) oscillations in vivo. When PV BCs are driven at these frequencies in vitro, inhibitory postsynaptic currents (IPSCs) in synaptically connected CA1 pyramidal cells exhibit paired-pulse depression (PPD) and multiple-pulse depression (MPD). Moreover, PV BCs express presynaptic muscarinic acetylcholine receptors (mAChRs) that may be activated by synaptically released acetylcholine during learning behaviors in vivo. Using acute hippocampal slices from the CA1 hippocampus of juvenile PV-GFP mice, we performed whole cell recordings from synaptically connected PV BC-CA1 pyramidal cell pairs to investigate how bath application of 10 μM muscarine impacts PPD and MPD at CA1 PV BC-pyramidal cell synapses. In accordance with previous studies, PPD and MPD magnitude increased with stimulation frequency. mAChR activation reduced IPSC amplitude and transiently reduced PPD, but MPD was largely maintained. Consistent with a reduction in release probability ( pr), MPD and mAChR activation increased both the coefficient of variation of IPSC amplitudes and the fraction of failures. Using variance-mean analysis, we converted MPD trains to pr functions and developed a kinetic model that optimally fit six distinct pr conditions. The model revealed that vesicular depletion caused MPD and that recovery from depression was dependent on calcium. mAChR activation reduced the presynaptic calcium transient fourfold and initial pr twofold, thereby reducing PPD. However, mAChR activation slowed calcium-dependent recovery from depression during sustained repetitive activity, thereby preserving MPD. Thus the activation of presynaptic mAChRs optimally protects PV BCs from vesicular depletion during short bursts of high-frequency activity.

scholarly journals Classical and atypical agonists activate M1 muscarinic acetylcholine receptors through common mechanisms

2015 ◽  
Vol 97 ◽  
pp. 27-39 ◽  
Author(s):  
Alena Randáková ◽  
Eva Dolejší ◽  
Vladimír Rudajev ◽  
Pavel Zimčík ◽  
Vladimír Doležal ◽  
...  
Keyword(s):  
Acetylcholine Receptors ◽  
Muscarinic Acetylcholine Receptors ◽  
Muscarinic Acetylcholine ◽  
M1 Muscarinic

Comparison of subcellular distribution and functions between exogenous and endogenous M1 muscarinic acetylcholine receptors

Life Sciences ◽  
2013 ◽  
Vol 93 (1) ◽  
pp. 17-23 ◽  
Author(s):  
Shigeru Morishima ◽  
Abu Syed Md Anisuzzaman ◽  
Junsuke Uwada ◽  
Hatsumi Yoshiki ◽  
Ikunobu Muramatsu
Keyword(s):  
Subcellular Distribution ◽  
Acetylcholine Receptors ◽  
Muscarinic Acetylcholine Receptors ◽  
Muscarinic Acetylcholine ◽  
M1 Muscarinic
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