Acetylcholine (ACh) receptors (AChR) regulate neural circuit activity in multiple contexts. In humans, mutations in ionotropic acetylcholine receptor (iAChR) genes can cause neurological disorders, including myasthenia gravis and epilepsy. In Caenorhabditis elegans, iAChRs play multiple roles in the locomotor circuit. The cholinergic motor neurons express an ACR-2-containing pentameric AChR (ACR- 2R) comprised of ACR-2, ACR-3, ACR-12, UNC-38, and UNC-63 subunits. A gain-of-function mutation in the non-a subunit gene acr-2 [acr-2(gf)] causes defective locomotion as well as spontaneous convulsions. Previous studies of genetic suppressors of acr-2(gf) have provided insights into ACR-2R composition and assembly. Here, to further understand how the ACR-2R regulates neuronal activity, we expanded the suppressor screen for acr-2(gf)-induced convulsions. The majority of these suppressor mutations affect genes that play critical roles in synaptic transmission, including two novel mutations in the vesicular ACh transporter unc-17. In addition, we identified a role for a conserved major facilitator superfamily domain (MFSD) protein, mfsd-6, in regulating neural circuit activity. We further defined a role for the sphingosine (SPH) kinase (Sphk) sphk-1 in cholinergic neuron activity, independent of previously known signaling pathways. Overall, the genes identified in our study suggest that optimal modulation of synaptic activity is balanced by the differential activities of multiple pathways, and the novel alleles provide valuable reagents to further dissect neuronal mechanisms regulating the locomotor circuit.
|Number of pages||9|
|Journal||G3: Genes, Genomes, Genetics|
|State||Published - Jul 1 2017|
Bibliographical noteFunding Information:
We thank Bhavika Anandpura for assistance in mapping the ju815 allele. We thank Derek Sieburth for OJ802 and KP4010 strains and Shohei Mitani at National BioResource Project in Japan for deletion alleles. Some strains were provided by the Caenorhabditis Genetics Center, which is funded by the National Institutes of Health (NIH) Office of Research Infrastructure Programs (P40 OD010440). This work was supported in part by NIH institutional training grants (T32 NS007220 to K.A.M. and S.J.C. and T32 AG000216 to K.A.M.), and grants to S.J.C. (F32 NS081945 and K99 NS097638) and Y.J. (R01 NS035546). Y.J. is an investigator of the Howard Hughes Medical Institute.
© 2017 McCulloch et al.
- Acetylcholine receptor
- Acetylcholine transporter
- Major facilitator superfamily domain (MFSD) proteins
- Sphingosine kinase/sphk-1
ASJC Scopus subject areas
- Molecular Biology