Goalpha regulates volatile anesthetic action in Caenorhabditis elegans.
To identify genes controlling volatile anesthetic (VA) action, we have screened through existing Caenorhabditis elegans mutants and found that strains with a reduction in Go signaling are VA resistant. Loss-of-function mutants of the gene goa-1, which codes for the alpha-subunit of Go, have EC(50)s for the VA isoflurane of 1.7- to 2.4-fold that of wild type. Strains overexpressing egl-10, which codes for an RGS protein negatively regulating goa-1, are also isoflurane resistant. However, sensitivity to halothane, a structurally distinct VA, is differentially affected by Go pathway mutants. The RGS overexpressing strains, a goa-1 missense mutant found to carry a novel mutation near the GTP-binding domain, and eat-16(rf) mutants, which suppress goa-1(gf) mutations, are all halothane resistant; goa-1(null) mutants have wild-type sensitivities. Double mutant strains carrying mutations in both goa-1 and unc-64, which codes for a neuronal syntaxin previously found to regulate VA sensitivity, show that the syntaxin mutant phenotypes depend in part on goa-1 expression. Pharmacological assays using the cholinesterase inhibitor aldicarb suggest that VAs and GOA-1 similarly downregulate cholinergic neurotransmitter release in C. elegans. Thus, the mechanism of action of VAs in C. elegans is regulated by Goalpha, and presynaptic Goalpha-effectors are candidate VA molecular targets.
van Swinderen
B
B
Department of Anesthesiology, Division of Biology and Biomedical Sciences, Washington University School of Medicine, 660 S. Euclid Ave., St. Louis, Missouri 63110, USA.
Metz
L B
LB
Shebester
L D
LD
Mendel
J E
JE
Sternberg
P W
PW
Crowder
C M
CM
D000483:Alleles; D000818:Animals; D017173:Caenorhabditis elegans / Q000235:genetics* / Q000502:physiology; D002802:Cholinesterases / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D015536:Down-Regulation; D004351:Drug Resistance / Q000235:genetics; D019206:GTP-Binding Protein alpha Subunits, Gi-Go; D006221:Halothane / Q000494:pharmacology; D020962:Heterotrimeric GTP-Binding Proteins / Q000235:genetics* / Q000502:physiology*; D007530:Isoflurane / Q000494:pharmacology; D008954:Models, Biological; D009154:Mutation; D010641:Phenotype; D017434:Protein Structure, Tertiary; D015398:Signal Transduction; D014170:Transformation, Genetic
D007530:Isoflurane; D002802:Cholinesterases; D019206:GTP-Binding Protein alpha Subunits, Gi-Go; D020962:Heterotrimeric GTP-Binding Proteins; D006221:Halothane