Non-synaptic ion channels in insects — basic properties of currents and their modulation in neurons and skeletal muscles

Wicher, Dieter; Walther, Christoph; Wicher, Carola

doi:10.1016/s0301-0082(00)00066-6

Cited by 106 publications

(121 citation statements)

References 650 publications

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“…Functionally distinct sodium currents have been documented in various insect neurons, indicating existence of heterogeneous sodium channels with distinct gating properties in vivo (Byerly and Leung, 1988;Lapied et al, 1990Lapied et al, , 1999Wu, 1991, 1993 ;Schafer et al, 1994;O'Dowd, 1995;Le Corronc et al, 1999;Grolleau and Lapied, 2000;Wicher et al, 2001;Defaix and Lapied, 2005). A fundamental question is how insects produce heterogeneous sodium channels from a single gene.…”

Section: Introductionmentioning

confidence: 99%

Molecular and functional characterization of voltage-gated sodium channel variants from Drosophila melanogaster

Olson

Liu

Nomura

et al. 2008

Insect Biochemistry and Molecular Biology

107

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Extensive alternative splicing and RNA editing have been documented for the transcript of DmNa V (formerly para), the sole sodium channel gene in Drosophila melanogaster. However, the functional consequences of these post-transcriptional modifications are not well understood. In this study we isolated 64 full-length DmNa V cDNA clones from D. melanogaster adults. Based on the usage of 11 alternative exons, 64 clones could be grouped into 29 splice types. When expressed in Xenopus oocytes, 33 DmNa V variants generated sodium currents large enough for functional characterization. Among these variants, DmNa V 5-1 and DmNa V 7-1 channels activated at the most hyperpolarizing potentials, whereas DmNa V 1-6 and DmNa V 19 channels activated at the most depolarizing membrane potentials. We identified an A-to-I editing event in DmNa V 5-1 that is responsible for its uniquely low-voltage-dependent activation. The wide range of voltage dependence of gating properties exhibited by DmNa V variants represents a rich resource for future studies to determine the role of DmNa V in regulating sodium channel gating, pharmacology, and neuronal excitability in insects.

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Section: Introductionmentioning

confidence: 99%

Molecular and functional characterization of voltage-gated sodium channel variants from Drosophila melanogaster

Olson

Liu

Nomura

et al. 2008

Insect Biochemistry and Molecular Biology

107

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“…Dorsal unpaired median (DUM) neurons were used in this study, as they are the most comprehensively characterized neurons in the insect nervous system. They generate spontaneous action potentials and contain a range on voltage-gated and neurotransmitter-gated ion channels known to play fundamental roles in the insect nervous system (Grolleau and Lapied, 2000;Wicher et al, 2001). Furthermore, they contain all the ion channels groups targeted by insecticides to date and as such are a useful model for the purpose of this study.…”

Section: Isolation Of Insect Neuronsmentioning

confidence: 99%

“…Unfortunately 4-AP could not be used to block I K(A) as it also inhibits I K(Na) (Grolleau and Lapied, 1994;Wicher et al, 2001). The absence of I K(A) block when recording K Na channel currents causes somewhat of a dilemma given the reported modest inhibition of I K(A) by κ-HXTX-Hv1c in DUM neurons.…”

Section: Mj Windley Et Al / Neuropharmacology 16mentioning

confidence: 99%

Lethal effects of an insecticidal spider venom peptide involve positive allosteric modulation of insect nicotinic acetylcholine receptors

et al. 2017

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Please cite this article as: Windley, M.J., Vetter, I., Lewis, R.J., Nicholson, G.M., Lethal effects of an insecticidal spider venom peptide involve positive allosteric modulation of insect nicotinic acetylcholine receptors, Neuropharmacology (2017), doi: 10.1016/j.neuropharm.2017.04.008. This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. Highlights• The previously characterized BK Ca channel block is not responsible for the lethal excitatory toxicity of κ-HXTX-Hv1c • κ-HXTX-Hv1c is a positive allosteric modulator of the insect nicotinic acetylcholine receptor which acts by prolonging current decay and reversing receptor desensitization • The likely lethal target of κ-HXTX-Hv1c is the nicotinic acetylcholine receptor, acting by a mechanism similar to that of the insecticide spinosyn A. A B S T R A C Tκ-Hexatoxins (κ-HXTXs) are a family of excitotoxic insect-selective neurotoxins from Australian funnel-web spiders that are lethal to a wide range of insects, but display no toxicity towards vertebrates. The prototypic κ-HXTX-Hv1c selectively blocks native and expressed cockroach largeconductance calcium-activated potassium (BK Ca or K Ca 1.1) channels, but not their mammalian orthologs. Despite this potent and selective action on insect K Ca 1.1 channels, we found that the classical K Ca 1.1 blockers paxilline, charybdotoxin and iberiotoxin, which all block insect K Ca 1.1 channels, are not lethal in crickets. We therefore used whole-cell patch-clamp analysis of cockroach dorsal unpaired median (DUM) neurons to study the effects of κ-HXTX-Hv1c on sodium-activated (K Na ), delayed-rectifier (K DR ) and 'A-type' transient (K A ) K + channels. 1 µM κ-HXTX-Hv1c failed to significantly inhibit cockroach K Na and K DR channels, but did cause a 30 ± 7% saturating inhibition of K A channel currents, possibly via a Kv4 (Shal-like) action. However, this modest action at such a high concentration of κ-HXTX-Hv1c would indicate a different lethal target. Accordingly, we assessed the actions of κ-HXTX-Hv1c on neurotransmitter-gated ion channels in cockroach DUM neurons. We found that κ-HXTX-Hv1c failed to produce any major effects on GABA A or glutamate-Cl receptors but dramatically slowed nicotine-evoked ACh receptor (nAChR) current decay and reversed nAChR desensitization. These actions occurred without any alterations to nAChR current amplitude or the nicotine concentration-response curve, and are consistent with a positive allosteric modulation of nAChRs. κ-HXTX-Hv1c therefore represents the first venom peptide that selectively modulates insect nAChRs with a mode of action similar to the excitotoxic insecticide spino...

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“…35) The cockroach AKH (also designated as neurohormone D) is an octapeptide, pQVNFSPNWamide and modulates Ca 2ϩ and Na ϩ currents in the dorsal unpaired median neuron. 36) …”

Section: Adipokinetic Hormone (Akh) / Red-pigment Concentrating Hormomentioning

confidence: 99%

Molecular physiology of crustacean and insect neuropeptides

Mercier¹,

Doucet

Retnakaran³

2007

J. Pestic. Sci.

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One of the principal hallmarks of a living organism is its ability to respond to stimuli. As the unicellular organisms evolved into multicellular metazoans, the external signals perceived had to be transduced to several other cells requiring a neuronal network with its accompanying biochemical neurotransmitters. The progressive increase in complexity of the organisms necessitated the need for an integrated signal transducing system collecting external sensory stimuli and sending them to effector systems such that a dynamic equilibrium or homeostasis, which is essential for survival, could be maintained. During the course of evolution many advanced sense organs were developed to detect various parameters in the environment, and concomitantly different internal effector systems were formed to respond to these signals received from outside to maintain homeostasis. Coordination was achieved with a network of electrical conductors in the form of an arborized nervous system and a variety of hydrophilic biochemicals that acted as neurotransmitters carrying the sensory signals to the internal effector systems. As the animal became increasingly complex, a sophisticated neurotransmission system catering to the spatial and temporal needs during growth, development and reproduction had to be in place. Parts of the nervous tissue in many locations took on a secretory role and released protein signal transducers, the neuropeptides. A panoply of such neuropeptides exist in all organisms functioning as neurohormones, neurotransmitters or neuromodulators. Aspects of neuropeptide structure and function in insects and crustaceans have been reviewed by various authors. [1][2][3][4][5][6][7][8][9][10] The neuropeptides are ligands to their cognate receptors in the ef- Organisms have to constantly respond to environmental conditions to maintain a status of dynamic homeostasis for survival. As single celled organisms evolved into multicellular animals, intercellular and inter-organ communications became indispensable not only to orchestrate homeostasis but also to control the many events punctuating metazoan development. To accomplish this need, a signal transduction system was evolved, consisting of an arborized network of nerves as well as a collection of oligopeptide neurotransmitters (neuropeptides) along with their cognate receptors. We review here the current state of our understanding of the physiology of neuropeptides in the most species-rich group of animals, the crustaceans and insects. The vast majority of neuropeptides signal through cell-surface guanosine-protein coupled receptors (GPCRs). These neuropeptide-receptor systems control a variety of physiological functions, for instance the numerous involuntary movements of internal ducts that are precisely timed for transporting reproductive, digestive and secretory materials. The rigid exoskeleton in Crustaceans and Insects require periodic molts to accomplish growth and metamorphosis and this is harmoniously regulated by a cascade of neuropeptides. Neuropeptides also regul...

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Non-synaptic ion channels in insects — basic properties of currents and their modulation in neurons and skeletal muscles

Cited by 106 publications

References 650 publications

Molecular and functional characterization of voltage-gated sodium channel variants from Drosophila melanogaster

Molecular and functional characterization of voltage-gated sodium channel variants from Drosophila melanogaster

Lethal effects of an insecticidal spider venom peptide involve positive allosteric modulation of insect nicotinic acetylcholine receptors

Molecular physiology of crustacean and insect neuropeptides

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