Schistosome I/Lamides – A new family of bioactive helminth neuropeptides

Abstract

Here we report the identification of a new family of helminth neuropeptides with members in both nematodes and flatworms, and include preliminary cell biological and functional characterisation of one of the peptides from the trematode parasite of humans, Schistosoma mansoni. Bioinformatics and Rapid Amplification of cDNA Ends (RACE)-PCR were used to identify the complete S. mansoni neuropeptide precursor gene Sm-npp-1, which encodes three pentapeptides bearing the motif (A/G)FVR(I/L).NH2. Similar peptides were identified in three other flatworm species and in 15 nematode species. Quantitative PCR (qPCR) and immunocytochemical (ICC) analyses showed that Sm-npp-1 is constitutively expressed in larval and adult worms. ICC and confocal microscopy were employed to localise one of the schistosome NPP-1 peptides (GFVRIamide) in adult worms and schistosomules; antibodies labelled a pair of neurones in the cerebral ganglia that extend posteriorly along the main nerve cords. GFVRIamide displayed no detectable co-localisation with FMRFamide-like peptides (FLPs), nor was it detectable in muscle innervation. Exogenously applied peptide had a significant inhibitory effect on the mobility of whole adult worm pairs at 10−5 M (n=9). Finally, we explored Sm-npp-1 function in schistosomules using RNA interference (RNAi); we successfully achieved specific knockdown of the Sm-npp-1 transcript (54.46±10.41 % knockdown, n=3), but did not detect any clear, aberrant mobility or morphological phenotypes. NPP-1-like peptides are a new family of helminth peptides with a cell-specific expression pattern distinct from FLPs and a modulatory effect on schistosome muscular activity.

Calmodulin disruption impacts growth and motility in juvenile liver fluke

“…Motivated by reports of CaM RNAi phenotypes in other helminths [ 13 , 33 ] we focused here on assessing CaM function in juvenile fluke, given the amenability of this life-cycle stage to our target validation platform for fluke that encompasses RNAi methods [ 21 , 22 , 34 ] and diverse functional assay platforms. A primary motivation for focusing on CaM, a protein intimately involved in cellular Ca 2+ signalling processes, is the fact that Ca 2+ signalling and regulation play key roles in neuromuscular function, which represents a well-established repository of targets for empirically-discovered anthelmintics [ 35 ]. Indeed, the disruption of Ca 2+ regulation by praziquantel, the drug of choice for the treatment of schistosome and tapeworm infections, directly highlights the validity of interventions disrupting Ca 2+ signalling/regulation.…”

Proteomic Analysis of the Schistosoma mansoni Miracidium

“…A report has indicated possible inter-species differences in the functions of GFVRIamide, which fall into the broad I/Lamide family, due to the apparent lack of conservation and difference in expression [ 101 ]. Recently described, the novel GFVRIamide has been linked to potential neuromuscular and interneuronal communication roles in the adult worm, suggesting a putative role also in the miracidium [ 101 ]. RLamide and RGMIamide are newly described novel peptides that fall into the same I/Lamide family, and along with the PWamides all have unknown phenotypical expression across the phylum Platyhelminthes.…”

The neuroactive substances and associated muscle system in Rhipidocotyle campanula (Digenea, Bucephalidae) from the intestine of the pike Esox lucius

“…Several neuropeptides families were found in Platyhelminthes (Day & Maule, 1999;Koziol et al, 2016;McVeigh et al, 2005McVeigh et al, , 2011. Among them, special attention was paid to the FMRFamide-related peptides (Gustafsson, 1987;Halton & Maule, 2004;Kreshchenko, Terenina, & Kuchin, 2018;Leksomboon et al, 2012;Petrov, Podvyaznaya, & Zaitseva, 2019).…”