scholarly journals Slo2 potassium channel function depends on a SCYL1 protein

2019 ◽  
Author(s):  
Long-Gang Niu ◽  
Ping Liu ◽  
Zhao-Wen Wang ◽  
Bojun Chen
Keyword(s):  
Rna Editing ◽  
Single Channel ◽  
Expression System ◽  
Mrna Level ◽  
Wild Type ◽  
Neuronal Function ◽  
Heterologous Expression System ◽  
Open Probability ◽  
C Elegans ◽  
Evolutionarily Conserved

AbstractSlo2 potassium channels play important roles in neuronal function, and their mutations in humans cause epilepsies and cognitive defects. However, little is known how Slo2 function is regulated by other proteins. Here we found that the function of C. elegans Slo2 (SLO-2) depends on adr-1, a gene important to RNA editing. However, slo-2 transcripts have no detectable RNA editing events and exhibit similar expression levels in wild type and adr-1 mutants. In contrast, mRNA level of scyl-1, which encodes an orthologue of mammalian SCYL1, is greatly reduced in adr-1 mutants due to deficient RNA editing at a single adenosine in its 3’-UTR. SCYL-1 physically interacts with SLO-2 in neurons. Single-channel open probability of SLO-2 in neurons is reduced by ∼50% in scyl-1 knockout whereas that of human Slo2.2/Slack is doubled by SCYL1 in a heterologous expression system. These results suggest that SCYL-1/SCYL1 is an evolutionarily conserved regulator of Slo2 channels.

scholarly journals Slo2 potassium channel function depends on RNA editing-regulated expression of a SCYL1 protein

eLife ◽  
2020 ◽  
Vol 9 ◽  
Author(s):  
Long-Gang Niu ◽  
Ping Liu ◽  
Zhao-Wen Wang ◽  
Bojun Chen
Keyword(s):  
Rna Editing ◽  
Single Channel ◽  
Expression System ◽  
Wild Type ◽  
Neuronal Function ◽  
Knockout Mutant ◽  
Open Probability ◽  
C Elegans ◽  
Evolutionarily Conserved ◽  
Regulated Expression

Slo2 potassium channels play important roles in neuronal function, and their mutations in humans may cause epilepsies and cognitive defects. However, it is largely unknown how Slo2 is regulated by other proteins. Here we show that the function of C. elegans Slo2 (SLO-2) depends on adr-1, a gene important to RNA editing. ADR-1 promotes SLO-2 function not by editing the transcripts of slo-2 but those of scyl-1, which encodes an orthologue of mammalian SCYL1. Transcripts of scyl-1 are greatly decreased in adr-1 mutants due to deficient RNA editing at a single adenosine in their 3’-UTR. SCYL-1 physically interacts with SLO-2 in neurons. Single-channel open probability (Po) of neuronal SLO-2 is ~50% lower in scyl-1 knockout mutant than wild type. Moreover, human Slo2.2/Slack Po is doubled by SCYL1 in a heterologous expression system. These results suggest that SCYL-1/SCYL1 is an evolutionarily conserved regulator of Slo2 channels.

scholarly journals Melatonin promotes sleep by activating the BK channel in C. elegans

2020 ◽  
Vol 117 (40) ◽  
pp. 25128-25137
Author(s):  
Longgang Niu ◽  
Yan Li ◽  
Pengyu Zong ◽  
Ping Liu ◽  
Yuan Shui ◽  
...  
Keyword(s):  
G Protein ◽  
Neurotransmitter Release ◽  
Expression System ◽  
Molecular Target ◽  
Bk Channel ◽  
G Protein Coupled Receptors ◽  
Wild Type ◽  
Heterologous Expression System ◽  
C Elegans ◽  
G Protein Coupled

Melatonin (Mel) promotes sleep through G protein-coupled receptors. However, the downstream molecular target(s) is unknown. We identified the Caenorhabditis elegans BK channel SLO-1 as a molecular target of the Mel receptor PCDR-1-. Knockout of pcdr-1, slo-1, or homt-1 (a gene required for Mel synthesis) causes substantially increased neurotransmitter release and shortened sleep duration, and these effects are nonadditive in double knockouts. Exogenous Mel inhibits neurotransmitter release and promotes sleep in wild-type (WT) but not pcdr-1 and slo-1 mutants. In a heterologous expression system, Mel activates the human BK channel (hSlo1) in a membrane-delimited manner in the presence of the Mel receptor MT1 but not MT2. A peptide acting to release free Gβγ also activates hSlo1 in a MT1-dependent and membrane-delimited manner, whereas a Gβλ inhibitor abolishes the stimulating effect of Mel. Our results suggest that Mel promotes sleep by activating the BK channel through a specific Mel receptor and Gβλ.

scholarly journals Gain-of-function variant of the human epithelial sodium channel

2013 ◽  
Vol 304 (2) ◽  
pp. F207-F213 ◽  
Author(s):  
Jingxin Chen ◽  
Thomas R. Kleyman ◽  
Shaohu Sheng
Keyword(s):  
Single Channel ◽  
Expression System ◽  
Surface Expression ◽  
Wild Type ◽  
Open Probability ◽  
Gain Of Function ◽  
Human Disorders ◽  
Human Genome Sequencing ◽  
Xenopus Oocyte Expression ◽  
Salt Sensitive Hypertension

Epithelial Na+ channel (ENaC) mutations are associated with several human disorders, underscoring the importance of these channels in human health. Recent human genome sequencing projects have revealed a large number of ENaC gene variations, several of which have been found in individuals with salt-sensitive hypertension, cystic fibrosis, and other disorders. However, the functional consequences of most variants are unknown. In this study, we used the Xenopus oocyte expression system to examine the functional properties of a human ENaC variant. Oocytes expressing αβγL511Q human ENaCs showed 4.6-fold greater amiloride-sensitive currents than cells expressing wild-type channels. The γL511Q variant did not significantly alter channel surface expression. Single channel recordings revealed that the variant had fourfold higher open probability than wild type. In addition, γL511Q largely eliminated the Na+ self-inhibition response, which reflects a downregulation of ENaC open probability by extracellular Na+. Moreover, γL511Q diminished chymotrypsin-induced activation of the mutant channel. We conclude that γL511Q is a gain-of-function human ENaC variant. Our results suggest that γL511Q enhances ENaC activity by increasing channel open probability and dampens channel regulation by extracellular Na+ and proteases.

scholarly journals Genetic, Behavioral and Environmental Determinants of Male Longevity in Caenorhabditis elegans

Genetics ◽  
2000 ◽  
Vol 154 (4) ◽  
pp. 1597-1610 ◽  
Author(s):  
David Gems ◽  
Donald L Riddle
Keyword(s):  
Caenorhabditis Elegans ◽  
Life Span ◽  
Wild Type ◽  
Neuronal Function ◽  
Nematode Caenorhabditis Elegans ◽  
Wild Isolate ◽  
Young Males ◽  
C Elegans ◽  
Single Sex ◽  
Solitary Males

Abstract Males of the nematode Caenorhabditis elegans are shorter lived than hermaphrodites when maintained in single-sex groups. We observed that groups of young males form clumps and that solitary males live longer, indicating that male-male interactions reduce life span. By contrast, grouped or isolated hermaphrodites exhibited the same longevity. In one wild isolate of C. elegans, AB2, there was evidence of copulation between males. Nine uncoordinated (unc) mutations were used to block clumping behavior. These mutations had little effect on hermaphrodite life span in most cases, yet many increased male longevity even beyond that of solitary wild-type males. In one case, the neuronal function mutant unc-64(e246), hermaphrodite life span was also increased by up to 60%. The longevity of unc-4(e120), unc-13(e51), and unc-32(e189) males exceeded that of hermaphrodites by 70–120%. This difference appears to reflect a difference in sex-specific life span potential revealed in the absence of male behavior that is detrimental to survival. The greater longevity of males appears not to be affected by daf-2, but is influenced by daf-16. In the absence of male-male interactions, median (but not maximum) male life span was variable. This variability was reduced when dead bacteria were used as food. Maintenance on dead bacteria extended both male and hermaphrodite longevity.

scholarly journals Membrane-delimited Inhibition of Maxi-K Channel Activity by the Intermediate Conductance Ca2+-activated K Channel

2006 ◽  
Vol 127 (2) ◽  
pp. 159-169 ◽  
Author(s):  
Jill Thompson ◽  
Ted Begenisich
Keyword(s):  
Single Channel ◽  
Expression System ◽  
Chemical Activation ◽  
K Channel ◽  
Channel Activity ◽  
Single Family ◽  
Open Probability ◽  
K Channels ◽  
Channel Proteins ◽  
K Activity

The complexity of mammalian physiology requires a diverse array of ion channel proteins. This diversity extends even to a single family of channels. For example, the family of Ca2+-activated K channels contains three structural subfamilies characterized by small, intermediate, and large single channel conductances. Many cells and tissues, including neurons, vascular smooth muscle, endothelial cells, macrophages, and salivary glands express more than a single class of these channels, raising questions about their specific physiological roles. We demonstrate here a novel interaction between two types of Ca2+-activated K channels: maxi-K channels, encoded by the KCa1.1 gene, and IK1 channels (KCa3.1). In both native parotid acinar cells and in a heterologous expression system, activation of IK1 channels inhibits maxi-K activity. This interaction was independent of the mode of activation of the IK1 channels: direct application of Ca2+, muscarinic receptor stimulation, or by direct chemical activation of the IK1 channels. The IK1-induced inhibition of maxi-K activity occurred in small, cell-free membrane patches and was due to a reduction in the maxi-K channel open probability and not to a change in the single channel current level. These data suggest that IK1 channels inhibit maxi-K channel activity via a direct, membrane-delimited interaction between the channel proteins. A quantitative analysis indicates that each maxi-K channel may be surrounded by four IK1 channels and will be inhibited if any one of these IK1 channels opens. This novel, regulated inhibition of maxi-K channels by activation of IK1 adds to the complexity of the properties of these Ca2+-activated K channels and likely contributes to the diversity of their functional roles.

Caenorhabditis elegansPlexinA, PLX-1, interacts with transmembrane semaphorins and regulates epidermal morphogenesis

Development ◽  
2002 ◽  
Vol 129 (9) ◽  
pp. 2053-2063 ◽  
Author(s):  
Takashi Fujii ◽  
Fumi Nakao ◽  
Yukimasa Shibata ◽  
Go Shioi ◽  
Eiji Kodama ◽  
...  
Keyword(s):  
Rna Interference ◽  
Morphological Changes ◽  
Expression System ◽  
Transmembrane Proteins ◽  
Axonal Guidance ◽  
Heterologous Expression System ◽  
C Elegans ◽  
Morphological Defects ◽  
Epidermal Morphogenesis ◽  
Null Mutants

The plexin family transmembrane proteins are putative receptors for semaphorins, which are implicated in the morphogenesis of animal embryos, including axonal guidance. We have generated and characterized putative null mutants of the C. elegans plexinA gene, plx-1. plx-1 mutants exhibited morphological defects: displacement of ray 1 and discontinuous alae. The epidermal precursors for the affected organs were aberrantly arranged in the mutants, and a plx-1::gfp transgene was expressed in these epidermal precursor cells as they underwent dynamic morphological changes. Suppression of C. elegans transmembrane semaphorins, Ce-Sema-1a and Ce-Sema-1b, by RNA interference caused a displacement of ray 1 similar to that of plx-1 mutants, whereas mutants for the Ce-Sema-2a/mab-20 gene, which encodes a secreted-type semaphorin, exhibited phenotypes distinct from those of plx-1 mutants. A heterologous expression system showed that Ce-Sema-1a, but not Ce-Sema-2a, physically bound to PLX-1. Our results indicate that PLX-1 functions as a receptor for transmembrane-type semaphorins, and, though Ce-Sema-2a and PLX-1 both play roles in the regulation of cellular morphology during epidermal morphogenesis, they function rather independently.

scholarly journals Temporal Transcriptomics of Gut Escherichia coli in Caenorhabditis elegans Models of Aging

2021 ◽  
Author(s):  
Joshua D. Brycki ◽  
Jeremy R. Chen See ◽  
Gillian R. Letson ◽  
Cade S. Emlet ◽  
Lavinia V. Unverdorben ◽  
...  
Keyword(s):  
Gene Expression ◽  
Escherichia Coli ◽  
Caenorhabditis Elegans ◽  
Life Span ◽  
Wild Type ◽  
Health Span ◽  
Content Type ◽  
C Elegans ◽  
Evolutionarily Conserved

Previous research has reported effects of the microbiome on health span and life span of Caenorhabditis elegans , including interactions with evolutionarily conserved pathways in humans. We build on this literature by reporting the gene expression of Escherichia coli OP50 in wild-type (N2) and three long-lived mutants of C. elegans .

scholarly journals Dual Effect of Tamoxifen on Arterial KCa Channels Does Not Depend on the Presence of the β1 Subunit

2005 ◽  
Vol 280 (23) ◽  
pp. 21739-21747 ◽  
Author(s):  
Guillermo J. Pérez
Keyword(s):  
Molecular Mechanisms ◽  
Single Channel ◽  
Protective Role ◽  
Wild Type ◽  
Open Probability ◽  
Dual Effect ◽  
Knock Out ◽  
Kca Channels ◽  
Molecular Specificity ◽  
Excised Patches

Tamoxifen has been reported to directly activate large conductance calcium-activated potassium (KCa) channels through the KCa β1 subunit, suggesting a cardio-protective role of this compound. The present study using knock-out (KO) mice for the KCa channel β1 subunit was aimed at understanding the molecular mechanisms of the effects of tamoxifen on arterial smooth muscle KCa channels. Single channel studies were conducted in excised patches from cerebral artery myocytes from both wild-type and KO animals. The present data demonstrated that tamoxifen can inhibit arterial KCa channels due to a major decrease in channel open probability (Po), a mechanism different from the reduction in single channel amplitude reported previously and also observed in the present work. A tamoxifen-induced decrease in Po was present in arterial KCa channels from both wild-type and β1 KO animals. This inhibition was concentration-dependent and partially reversible with a half-maximal concentration constant IC50 of 2.6 μm. The effect of tamoxifen was actually dual Single channel kinetic analysis showed that tamoxifen shortens both mean closed time and mean open time; the latter is probably due to an intermediate duration voltage-independent blocking mechanism. Thus, tamoxifen block would predominate when KCa channel Po is >0.1–0.2, limiting the maximum Po, whereas a leftward shift in voltage or Ca2+ activation curves can be observed for Po values lower than those values. This dual effect of tamoxifen appears to be independent of the β1 subunit. The molecular specificity of tamoxifen, or eventually other xenoestrogen derivatives, for the KCa channel β1 subunit is uncertain.

scholarly journals A molecular link between activation and inactivation of sodium channels.

1995 ◽  
Vol 106 (4) ◽  
pp. 641-658 ◽  
Author(s):  
M E O'Leary ◽  
L Q Chen ◽  
R G Kallen ◽  
R Horn
Keyword(s):  
Sodium Channels ◽  
Voltage Dependence ◽  
Single Channel ◽  
Critical Role ◽  
Channel Measurements ◽  
Wild Type ◽  
Open Probability ◽  
Voltage Dependent ◽  
Steady State Inactivation ◽  
Normal Coupling

A pair of tyrosine residues, located on the cytoplasmic linker between the third and fourth domains of human heart sodium channels, plays a critical role in the kinetics and voltage dependence of inactivation. Substitution of these residues by glutamine (Y1494Y1495/QQ), but not phenylalanine, nearly eliminates the voltage dependence of the inactivation time constant measured from the decay of macroscopic current after a depolarization. The voltage dependence of steady state inactivation and recovery from inactivation is also decreased in YY/QQ channels. A characteristic feature of the coupling between activation and inactivation in sodium channels is a delay in development of inactivation after a depolarization. Such a delay is seen in wild-type but is abbreviated in YY/QQ channels at -30 mV. The macroscopic kinetics of activation are faster and less voltage dependent in the mutant at voltages more negative than -20 mV. Deactivation kinetics, by contrast, are not significantly different between mutant and wild-type channels at voltages more negative than -70 mV. Single-channel measurements show that the latencies for a channel to open after a depolarization are shorter and less voltage dependent in YY/QQ than in wild-type channels; however the peak open probability is not significantly affected in YY/QQ channels. These data demonstrate that rate constants involved in both activation and inactivation are altered in YY/QQ channels. These tyrosines are required for a normal coupling between activation voltage sensors and the inactivation gate. This coupling insures that the macroscopic inactivation rate is slow at negative voltages and accelerated at more positive voltages. Disruption of the coupling in YY/QQ alters the microscopic rates of both activation and inactivation.

A conserved cytoplasmic region of ROMK modulates pH sensitivity, conductance, and gating

1997 ◽  
Vol 273 (4) ◽  
pp. F516-F529 ◽  
Author(s):  
Han Choe ◽  
Hao Zhou ◽  
Lawrence G. Palmer ◽  
Henry Sackin
Keyword(s):  
Single Channel ◽  
Ph Sensitivity ◽  
Channel Noise ◽  
Wild Type ◽  
Channel Conductance ◽  
Single Channel Conductance ◽  
Open Probability ◽  
Hydrophobic Region ◽  
K Secretion ◽  
Single Channel Currents

ROMK channels play a key role in overall K balance by controlling K secretion across the apical membrane of mammalian cortical collecting tubule. In contrast to the family of strong inward rectifiers (IRKs), ROMK channels are markedly sensitive to intracellular pH. Using Xenopus oocytes, we have confirmed this pH sensitivity at both the single-channel and whole cell level. Reduction of oocyte pH from 6.8 to 6.4 (using a permeant acetate buffer) reduced channel open probability from 0.76 ± 0.02 to near zero ( n = 8), without altering single-channel conductance. This was due to the appearance of a long-lived closed state at low internal pH. We have confirmed that a lysine residue (K61 on ROMK2; K80 on ROMK1), NH2 terminal to the first putative transmembrane segment (M1), is primarily responsible for conferring a steep pH sensitivity to ROMK (B. Fakler, J. Schultz, J. Yang, U. Schulte, U. Bråandle, H. P. Zenner, L. Y. Jan, and J. P. Ruppersberg. EMBO J. 15: 4093–4099, 1996). However, the apparent p K a of ROMK also depends on another residue in a highly conserved, mildly hydrophobic area: T51 on ROMK2 (T70 on ROMK1). Replacing this neutral threonine (T51) with a negatively charged glutamate shifted the apparent p K a for inward conductance from 6.5 ± 0.01 ( n = 8, wild type) to 7.0 ± 0.02 ( n = 5, T51E). On the other hand, replacing T51 with a positively charged lysine shifted the apparent p K a in the opposite direction, from 6.5 ± 0.01 ( n = 8, wild type) to 6.0 ± 0.02 ( n = 9, T51K). The opposite effects of the glutamate and lysine substitutions at position 51 (ROMK2) are consistent with a model in which T51 is physically close to K61 and alters either the local pH or the apparent p K a via an electrostatic mechanism. In addition to its effects on pH sensitivity, the mutation T51E also decreased single-channel conductance from 34.0 ± 1.0 pS ( n = 8, wild type) to 17.4 ± 1 pS ( n = 9, T51E), reversed the voltage gating of the channel, and significantly increased open-channel noise. These effects on single-channel currents suggest that the T51 residue, located in a mildly hydrophobic area of ROMK2, also interacts with the hydrophobic region of the permeation pathway.

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