Characterization and expression profile of transient receptor potential channels in sea cucumber Apostichopus japonicus

Abstract

BackgroundIn the past few decades, heat waves and seasonal variation linked with global warming are causing frequent fluctuations of water temperature in aquatic environments, resulting in further challenges for marine organisms. As a poikilothermic marine animal and a temperate species, sea cucumber A. japonicus is also very sensitive to temperature variation and shows a limited ability to adapt to environmental temperature changes. However, the molecular mechanisms by which A. japonicus perceives signals from such a diverse environment including the trigger of aestivation still remain unclear. TRP (transient receptor potential) superfamily, as the great potential “sentinel” of the organism in response to the changes of the external environment signals, perceived little attention and will be the future great candidates for sensory function research in echinoderm.MethodsBLAST program was applied to identify the AjTRPs based on A. japonicus transcriptome database. Gene structure analysis of AjTRPs and phylogenetic analysis of TRPs were performed. The expression profiles of AjTRPs in different tissues and in response to different heat stress treatments (chronic/ acute) were measured using qRT-PCR.ResultsA total of 54 TRPs were identified in A. japonicus. Gene structure analysis showed that the exon numbers and the domains of AjTRPs varied greatly. Phylogenetic analysis indicated that AjTPRs were mainly grouped into six subfamilies: TRPA, TRPM, TRPC, TRPV, TRPML, and TRPP. Copy numbers of each TRP member in marine invertebrates including A. japonicus were more than those in vertebrates, however some TRP channel members were lost in invertebrates. Expression profile detection suggested that the representative 15 AjTRP genes belonging to 6 subfamilies were expressed in all tissues examined.ConclusionOur findings indicate that the plastic evolutionary history of TRP channel genes and suggest that TRPM2-1, TRPM2-2, TRPM3, and TRPC3-1 are potential thermo-TRP proteins involved in thermal regulation in A. japonicus. This work facilitates the knowledge of TRP-mediated sensory systems in echinoderms, provides new insights into the mechanisms of aestivation and global warming adaptation in marine invertebrates.