Transcriptome analysis of sea cucumber (Apostichopus japonicus) polian vesicles in response to evisceration.

Polian vesicles are considered as the site of coelomocyte formation, and play crucial roles in the inflammatory reaction in sea cucumber. After evisceration, coelomocytes and internal organs except polian vesicles are excreted. Our previous study found that the total number of coelomocytes was rapidly recovered at 6 h post-evisceration in sea cucumber Apostichopus japonicus, and this regeneration of coelomocytes might be closely related to polian vesicles. To further investigate the related-gene expression pattern of the polian vesicles at 6 h post-evisceration, the transcriptome analysis of polian vesicles was carried out. A total of 2752 differentially expressed genes (DEGs) were identified, including 1,453 up-regulated genes and 1299 down-regulated genes. Gene Ontology (GO) enrichment showed that most of the DEGs were classified under Regulation of transcription, Regulation of RNA metabolic process, Regulation of nucleic acid-templated transcription. Meanwhile, 11 significantly enriched Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways were identified. Among them, Wnt, TGF-ß and Endocytosis pathways are well-related with cell proliferation and differentiation, which may be involved in the regeneration of coelomocytes in A. japonicus after evisceration. In addition, FoxO signaling pathway plays important roles in immunoregulation, in which the expression levels of the DEGs were significantly up-regulated, inferring that polian vesicles could not only participate in the coelomocyte regeneration process, but also undertake a certain immune defense function in A. japonicus after evisceration. These findings will be beneficial for understanding the mechanisms of coelomocyte regeneration and immune defense of A. japonicus after evisceration.