A genetic selection for Caenorhabditis elegans synaptic transmission mutants.

Miller, Kenneth G.; Alfonso, Aixa; Nguyen, Minh; Crowell, John A.; Johnson, Carl D.; Rand, James B.

doi:10.1073/pnas.93.22.12593

Cited by 401 publications

(420 citation statements)

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“…Aldicarb resistance can be quantified in a variety of ways, including acute assays, in which hypercontraction or paralysis are monitored over time (Lackner et al 1999;Nurrish et al 1999), or chronic assays, in which the ability to grow and reproduce is monitored (Miller et al 1996). We found that cho-1 mutants are just as sensitive as wild-type animals to 2 mm aldicarb in an acute assay (see below).…”

Section: Resultsmentioning

confidence: 72%

“…Resistance to the AChE inhibitor aldicarb is usually associated with decreased ACh release (Miller et al 1996). Aldicarb resistance can be quantified in a variety of ways, including acute assays, in which hypercontraction or paralysis are monitored over time (Lackner et al 1999;Nurrish et al 1999), or chronic assays, in which the ability to grow and reproduce is monitored (Miller et al 1996).…”

Section: Resultsmentioning

confidence: 99%

“…Swimming rates were measured on hermaphrodites raised at 20°as described previously (Miller et al 1996). Acute aldicarb-resistance assays were performed as described previously (Lackner et al 1999;Nurrish et al 1999), using 2 mm aldicarb.…”

Section: Methodsmentioning

confidence: 99%

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Choline Transport and de novo Choline Synthesis Support Acetylcholine Biosynthesis in Caenorhabditis elegans Cholinergic Neurons

Mullen

Mathews

et al. 2007

Genetics

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The cho-1 gene in Caenorhabditis elegans encodes a high-affinity plasma-membrane choline transporter believed to be rate limiting for acetylcholine (ACh) synthesis in cholinergic nerve terminals. We found that CHO-1 is expressed in most, but not all cholinergic neurons in C. elegans. cho-1 null mutants are viable and exhibit mild deficits in cholinergic behavior; they are slightly resistant to the acetylcholinesterase inhibitor aldicarb, and they exhibit reduced swimming rates in liquid. cho-1 mutants also fail to sustain swimming behavior; over a 33-min time course, cho-1 mutants slow down or stop swimming, whereas wildtype animals sustain the initial rate of swimming over the duration of the experiment. A functional CHO-1TGFP fusion protein rescues these cho-1 mutant phenotypes and is enriched at cholinergic synapses. Although cho-1 mutants clearly exhibit defects in cholinergic behaviors, the loss of cho-1 function has surprisingly mild effects on cholinergic neurotransmission. However, reducing endogenous choline synthesis strongly enhances the phenotype of cho-1 mutants, giving rise to a synthetic uncoordinated phenotype. Our results indicate that both choline transport and de novo synthesis provide choline for ACh synthesis in C. elegans cholinergic neurons.

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Section: Resultsmentioning

confidence: 72%

Section: Resultsmentioning

confidence: 99%

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Choline Transport and de novo Choline Synthesis Support Acetylcholine Biosynthesis in Caenorhabditis elegans Cholinergic Neurons

Mullen

Mathews

et al. 2007

Genetics

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“…To test this hypothesis, we used a well-established pharmacological assay to analyze the changes in cholinergic signaling (Miller et al, 1996). In this assay, animals are exposed to the cholinesterase inhibitor aldicarb, and a time course of paralysis is used to quantify defects in synaptic function.…”

Section: Rab-3 and Rab-27 Control Synaptic Transmissionmentioning

confidence: 99%

Regulation of Synaptic Transmission by RAB-3 and RAB-27 inCaenorhabditis elegans

Mahoney

Liu

Itoh

et al. 2006

MBoC

159

218

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Rab small GTPases are involved in the transport of vesicles between different membranous organelles. RAB-3 is an exocytic Rab that plays a modulatory role in synaptic transmission. Unexpectedly, mutations in the Caenorhabditis elegans RAB-3 exchange factor homologue, aex-3, cause a more severe synaptic transmission defect as well as a defecation defect not seen in rab-3 mutants. We hypothesized that AEX-3 may regulate a second Rab that regulates these processes with RAB-3. We found that AEX-3 regulates another exocytic Rab, RAB-27. Here, we show that C. elegans RAB-27 is localized to synapse-rich regions pan-neuronally and is also expressed in intestinal cells. We identify aex-6 alleles as containing mutations in rab-27. Interestingly, aex-6 mutants exhibit the same defecation defect as aex-3 mutants. aex-6; rab-3 double mutants have behavioral and pharmacological defects similar to aex-3 mutants. In addition, we demonstrate that RBF-1 (rabphilin) is an effector of RAB-27. Therefore, our work demonstrates that AEX-3 regulates both RAB-3 and RAB-27, that both RAB-3 and RAB-27 regulate synaptic transmission, and that RAB-27 potentially acts through its effector RBF-1 to promote soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) function. INTRODUCTIONNeurotransmitter release is accomplished by the fusion of neurotransmitter-filled synaptic vesicles at the presynaptic nerve terminal. This process occurs through a series of highly regulated steps that include synaptic vesicle transport, docking/tethering, priming, fusion, endocytosis, recycling, and neurotransmitter refilling (Sudhof, 2004). Several genes have been assigned roles in the various steps of the synaptic vesicle cycle. Rab3 (termed RAB-3 in Caenorhabditis elegans), a member of the Rab family of small GTPases, regulates synaptic transmission, possibly through the docking, priming, or fusion steps Schluter et al., 2004).Rabs act in a variety of cell types and regulate vesicular transport between organelles. Rabs cycle on and off membranes via a GTP-dependent mechanism (Zerial and McBride, 2001). Rab activity is regulated by two proteins, which act in an antagonistic manner. The guanine nucleotide exchange factor (GEF) exchanges GTP for GDP, and the GTPase activating protein activates the intrinsic GTPase activity of a Rab (Bernards, 2003). GDP bound Rabs are held off of the membrane by a GDP dissociation inhibitor (Wu et al., 1996). The GTP/membrane-bound form of Rabs typically binds to a variety of effectors that regulate particular steps of membrane transport and cell signaling (Zerial and McBride, 2001;Spang, 2004).Rab3 was once thought to play a central role in regulating release. However, recent work has shown that a quadruple knockout of all four isoforms of Rab3 in mice only results in a 30% reduction in evoked synaptic response (Schluter et al., 2004). This is consistent with work in C. elegans showing that mutations in the single rab-3 gene cause only mild defects in synaptic transmission . Surprisingly, more dramatic phe...

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“…Swimming (thrashing), pharyngeal pumping, and defecation were all measured on young adult hermaphrodites raised at 20°C as described previously (Miller et al, 1996). Acute aldicarb assays were performed as described previously (Lackner et al, 1999;Nurrish et al, 1999) using 2 mM aldicarb.…”

Section: Behavioral Assaysmentioning

confidence: 99%

TheCaenorhabditis elegans snf-11Gene Encodes a Sodium-dependent GABA Transporter Required for Clearance of Synaptic GABA

Mullen

Mathews

Saxena

et al. 2006

MBoC

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Sodium-dependent neurotransmitter transporters participate in the clearance and/or recycling of neurotransmitters from synaptic clefts. The snf-11 gene in Caenorhabditis elegans encodes a protein of high similarity to mammalian GABA transporters (GATs). We show here that snf-11 encodes a functional GABA transporter; SNF-11-mediated GABA transport is Na ؉ and Cl ؊ dependent, has an EC 50 value of 168 M, and is blocked by the GAT1 inhibitor SKF89976A. The SNF-11 protein is expressed in seven GABAergic neurons, several additional neurons in the head and retrovesicular ganglion, and three groups of muscle cells. Therefore, all GABAergic synapses are associated with either presynaptic or postsynaptic (or both) expression of SNF-11. Although a snf-11 null mutation has no obvious effects on GABAergic behaviors, it leads to resistance to inhibitors of acetylcholinesterase. In vivo, a snf-11 null mutation blocks GABA uptake in at least a subset of GABAergic cells; in a cell culture system, all GABA uptake is abolished by the snf-11 mutation. We conclude that GABA transport activity is not essential for normal GABAergic function in C. elegans and that the localization of SNF-11 is consistent with a GABA clearance function rather than recycling.

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A genetic selection for Caenorhabditis elegans synaptic transmission mutants.

Cited by 401 publications

References 50 publications

Choline Transport and de novo Choline Synthesis Support Acetylcholine Biosynthesis in Caenorhabditis elegans Cholinergic Neurons

Choline Transport and de novo Choline Synthesis Support Acetylcholine Biosynthesis in Caenorhabditis elegans Cholinergic Neurons

Regulation of Synaptic Transmission by RAB-3 and RAB-27 inCaenorhabditis elegans

TheCaenorhabditis elegans snf-11Gene Encodes a Sodium-dependent GABA Transporter Required for Clearance of Synaptic GABA

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