What can transcriptomic analyses reveal about the phylogenetic/structural conservation, tissue localization, and possible functions of CNMamide peptides in decapod crustaceans?

Authors: CHRISTIE, ANDREW - University Of Hawaii; Hull, Joe

Submitted to: General and Comparative Endocrinology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/4/2019
Publication Date: 10/1/2019
Citation: Christie, A.E., Hull, J.J. 2019. What can transcriptomic analyses reveal about the phylogenetic/structural conservation, tissue localization, and possible functions of CNMamide peptides in decapod crustaceans? General and Comparative Endocrinology. 282. https://doi.org/10.1016/j.ygcen.2019.113217.
DOI: https://doi.org/10.1016/j.ygcen.2019.113217

Interpretive Summary: Genomic and transcriptomic datasets have facilitated the identification of previously unknown peptide families and their cognate receptors among arthropods. One such group of peptide-receptor pairs, CNMamide and its associated receptor, were first identified in the fruitfly. The corresponding genes were recently found in a crayfish transcriptomic dataset suggesting their expression and function may extend to other arthropods, in particular decapods. To examine this possibility multiple publicly available datasets were scanned for similar sequences. Sequences predicted to encode the peptide-receptor pair were identified in all datasets examined indicating their evolutionary conservation. The presence of sequences within tissue specific datasets for nervous system and reproductive tissues suggests the peptide-receptor pair may function in modulating the two systems.

Technical Abstract: Over the past several years, in silico analyses of arthropod genomes/transcriptomes have led to the identification of several previously unknown peptide families. The CNMamides are one such peptide group, having been discovered via computational analyses of the fruit fly, Drosophila melanogaster, genome; both a CNMamide precursor and receptor were identified. Recently, a CNMamide family member, VMCHFKICNLamide (disulfide bridging between the cysteine residues), was predicted via in silico mining of a crayfish, Procambarus clarkii, transcriptome, suggesting the presence of this peptide group in members of the Decapoda. Here, using publically accessible transcriptomic data, the phylogenetic/structural conservation, tissue localization, and possible functions of the CNMamide family in decapods were explored. Evidence for CNMamide precursors was found for members of each decapod infraorder for which significant sequence data are available, suggesting a ubiquitous conservation of the CNMamide family in the Decapoda. For the Penaeoidea, Caridea, Astacidea and Achelata, the isoform of CNMamide originally identified from P. clarkii appears to be ubiquitously conserved; in members of the Brachyura, VMCHFKICNMamide (disulfide bridging between the cysteine residues) is the native isoform. Interestingly, the decapod CNMamide gene appears to also have a splice variant in which the carboxy-terminal portion of the preprohormone containing the CNMamide peptide is replaced by one containing a different disulfide bridged peptide that is structurally unrelated to it; this second peptide shows considerable conservation within, but variation among, decapod infraorders. A highly conserved putative CNMamide receptor was identified from members of the Penaeoidea, Astacidea and Brachyura. Phylogenetic analyses support the annotation of the decapod receptor as a true member of the CNMamide receptor family. The presence of precursor and receptor transcripts in both nervous system- and reproductive tissue-specific transcriptomes suggests CNMamides serve.