Transcriptome analysis reveals key transcription factors and pathways of polian vesicle associated with cell proliferation in Vibrio splendidus-challenged Apostichopus japonicus

Polian vesicle is thought to produce coelomocytes and contribute to the sea cucumber's immune system. Our previous work has indicated that polian vesicle was responsible for cell proliferation at 72 h post pathogenic challenge. However, the transcription factors related to the activation of effector factors and the molecular process behind this remained unknown. In this study, to reveal the early functions of polian vesicle in response to the microbe, a comparative transcriptome sequencing of polian vesicle in V. splendidus-challenged Apostichopus japonicus, including normal group (PV 0 h), pathogen challenging for 6 h (PV 6 h) and 12 h (PV 12 h) was performed. Compared PV 0 h to PV 6 h, PV 0 h to PV 12 h, and PV 6 h to PV 12 h, we found 69, 211, and 175 differentially expressed genes (DEGs), respectively. KEGG enrichment analysis revealed the DEGs, including several transcription factors such as fos, FOS-FOX, ATF2, egr1, KLF2, and Notch3 between PV 6 h and PV 12 h were consistently enriched in MAPK, Apelin and Notch3 signaling pathways related to cell proliferation compared with that in PV 0 h. Important DEGs involved in cell growth were chosen, and their expression patterns were almost the same as the transcriptome profile analysis by qPCR. Protein interaction network analysis indicated that two DEGs of fos and egr1 were probably significant as key candidate genes controlling cell proliferation and differentiation in polian vesicle after pathogenic infection in A. japonicus. Overall, our analysis demonstrates that polian vesicles may play an essential role in regulating proliferation via transcription factors-mediated signaling pathway in A. japonicus and provide new insights into hematopoietic modulation of polian vesicles in response to pathogen infection.