AMGSELFamide, a member of a broadly conserved peptide family, modulates multiple neural networks in Homarus americanus

Authors: DICKINSON, PATSY - Bowdoin College; DICKINSON, EVYN - Bowdoin College; BERGSTROM, MARIE - Bowdoin College; OLEISKY, EMILY - Bowdoin College; RIVERA, CINDY - Bowdoin College; STANHOPE, MEREDITH - Bowdoin College; STEMMLER, ELIZABETH - Bowdoin College; Hull, Joe; CHRISTIE, ANDREW - University Of Hawaii

Submitted to: Journal of Experimental Biology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/15/2018
Publication Date: 1/18/2019
Citation: Dickinson, P.S., Dickinson, E.S., Bergstrom, M., Oleisky, E.R., Rivera, C.D., Stanhope, M.E., Stemmler, E.A., Hull, J.J., Christie, A.E. 2019. AMGSELFamide, a member of a broadly conserved peptide family, modulates multiple neural networks in Homarus americanus. Journal of Experimental Biology. 222:jeb194092-15. https://doi.org/10.1242/jeb.194092.
DOI: https://doi.org/10.1242/jeb.194092

Interpretive Summary: Peptides, which are generally composed of 50 or fewer amino acids, mediate a number of biological functions, typically via a core sequence that is shared across a number of peptides. Peptides can thus be grouped into families based on the presence of a shared sequence. One such peptide family predicted from diverse genomic data sets is characterized by a GSEFLamide sequence. Although this family is fairly well represented among the arthropods, little is known about their biological function. To begin to address this, we used the American lobster as a model for examining GSEFLamide function. PCR-based profiling of lobster brains confirmed expression of the GSEFLamide peptide transcripts were amplified using PCR methods from brains and mass spectrometry confirmed the presence of individual peptides. Functional analyses using synthetic lobster GSEFLamide peptides revealed roles in modulating rhythmic motor activities.

Technical Abstract: Recent genomic/transcriptomic studies have identified a novel peptide family whose members share the carboxyl terminal sequence –GSEFLamide. However, the presence/identity of the predicted isoforms of this peptide group have yet to be confirmed biochemically, and no physiological function has yet been ascribed to any member of this peptide family. To determine the extent to which GSEFLamides are conserved within the Arthropoda, we searched publicly accessible databases for genomic/transcriptomic evidence of their presence. GSEFLamides appear to be highly conserved within the Arthropoda, with the possible exception of the Insecta, in which sequence evidence was limited to the more basal orders. One crustacean in which GSEFLamides have been predicted using transcriptomics is the lobster, Homarus americanus. Expression of the previously published transcriptome-derived sequences was confirmed by reverse transcription (RT)-PCR of brain and eyestalk ganglia cDNAs; mass spectral analyses confirmed the presence of all six of the predicted GSEFLamide isoforms – IGSEFLamide, MGSEFLamide, AMGSEFLamide, VMGSEFLamide, ALGSEFLamide and AVGSEFLamide – in H. americanus brain extracts. AMGSEFLamide, of which there are multiple copies in the cloned transcripts, was the most abundant isoform detected in the brain. Because the GSEFLamides are present in the lobster nervous system, we hypothesized that they might function as neuromodulators, as is common for neuropeptides. We thus asked whether AMGSEFLamide modulates the rhythmic outputs of the cardiac ganglion and the stomatogastric ganglion. Physiological recordings showed that AMGSEFLamide potently modulates the motor patterns produced by both ganglia, suggesting that the GSEFLamides may serve as important and conserved modulators of rhythmic motor activity in arthropods.