Brain8. In nematodes betaine arrests larval improvement two. However, the molecular target of betaine is not known. The targets of synthetic anthelmintics are typically ligand-gated ion channels. The imidazothiazoles straight activate acetylcholine ated ion channels, which stimulates muscle contraction and paralyzes the worm9,10. The macrocyclic lactones open glutamate-gated chloride channels and inhibit pharyngeal pumping 113. Amino-acetonitrile derivatives (AADs) are a lately discovered class of compounds that target a nematodespecific ion channel, referred to as ACR-23 in C. elegans14. ACR-23 belongs towards the nicotinic acetylcholine receptor subfamily, but its homolog in parasitic nematodes, MPTL-1, just isn’t gated by acetylcholine or choline15. The endogenous ligand and biological function of ACR-23 stay to be characterized. In this manuscript, we study the role of betaine in the nematode C. elegans, and demonstrate that ACR-23 is really a betaine receptor. First, we characterize the betaine transporter SNF-3 and show that mutations in this transporter are subviable within a sensitized background lacking phospholipase C. Second, we demonstrate that mutations in acr-23 suppress this lethality, suggesting that excess betaine is acting through ACR-23. Third, we demonstrate that ACR-23 is gated by betaine and potentiated by the AAD monepantel. Therefore, ancient and modern day anthelmintics act on the exact same target: a betaine-activated ion channel that may be only found in nematodes.Nat Neurosci. Author manuscript; readily available in PMC 2014 June 01.Peden et al.PageResultsAn enhancer screen identifies a betaine transporter We were in a position to determine the betaine pathway inadvertently though studying phospholipase C function. Within the nematode C. elegans, mutants lacking the only phospholipase C gene (egl-8) exhibit subtle behavioral defects in locomotion and egg-laying, in contrast to the near lethal phenotype of mutants lacking Gq, the upstream activator of phospholipase C 16,17. This modest loss-of-function phenotype of egl-8 suggests the existence of parallel pathways to inositol signaling that modulate locomotion.ML277 site To uncover these pathways, we performed an F2 enhancer screen in an egl-8 mutant background.Mangafodipir Purity We screened 1669 haploid genomes and identified a single mutation that brought on a synthetic phenotype within the presence of an egl-8 mutation.PMID:23537004 Mapping, rescue and sequencing experiments demonstrated that the enhancer was an allele of the snf-3 gene (sodium neurotransmitter symporter family-3, Supplementary Fig. S1a). The snf-3 egl-8 double mutants exhibit serious synthetic phenotypes (Fig. 1a ): the strain is subviable, uncoordinated, and dumpy. The dumpy phenotype is brought on by hypercontraction in the muscle because it can be suppressed by mutations inside the contractile apparatus unc-22 (twitchin) and unc-54 (myosin) (information not shown)9. The hypercontracted phenotype of snf-3 egl-8 double mutants is fully synthetic: neither single mutant is hypercontracted (snf-3 egl-8 vs egl-8 in Fig. 1a , and snf-3 in Supplementary Fig. S1c). The uncoordinated phenotype can also be much more severe than that of either single mutant (Fig. 1cd). Several allelic combinations exhibit the exact same synthetic hypercontracted phenotype (data not shown), demonstrating that the phenotypes are usually not due to background mutations. snf-3 encodes a neurotransmitter transporter from the solute carrier 6 (SLC6) gene family members. Members of this transporter family members clear neurotransmitters from the synaptic cleft, like the neurotransmitters seroton.
