A signal recognition particle receptor gene from the sea cucumber, Apostichopus japonicas

The signal recognition particle (SRP) system delivers approximately 30% of the proteome to the endoplasmic reticulum (ER) membrane. SRP receptor alpha (SR alpha) binds to SRP for targeting nascent secreted proteins to the ER membrane in eukaryotic cells. In this study, the SR alpha homologous gene was identified in the sea cucumber, Apostichopus japonicus (AjSR alpha). AjSR alpha codes for 641 amino acids and has 54.94% identity with its mammalian homologs. Like mammalian SR alpha, it is expected to contain the SRP-alpha N domain, SRP54_N domain, and SRP54 domain. In addition, AjSR alpha is ubiquitously expressed in adult tissues and exhibits a sexually dimorphic expression pattern, with significantly higher expression in ovaries compared to testes. As a maternal factor, AjSR alpha can be continuously detected during embryonic development. Importantly, we first attempted to investigate its function by using lentiviral vectors for delivering SR alpha gene-specific shRNA, and we revealed that lentiviral vectors do not induce an upregulation of immune-related enzymes in sea cucumbers. However, compared to the dsRNA-based RNA interference (RNAi) method, lentivirus-mediated RNAi caused dynamic changes in gene expression at a later time. This study supplied the technical support for studying the functional mechanism of SR alpha in sea cucumbers.