Short communicationMolecular delineation of a caspase 10 homolog from black rockfish (Sebastes schlegelii) and its transcriptional regulation in response to pathogenic stress

- Homolog of caspase 3 was identified from black rockfish (RfCasp10)
- RfCasp10 showed marked homology with known caspase 10 counterparts.
- RfCasp10 gene spanned 13 exons separated by 12 introns.
- RfCasp10 ubiquitously expressed in physiologically important tissues
- RfCasp10 expression in selected tissues was markedly modulated by pathogen stress.

Caspase 10 is an initiator caspase in death cascades of death receptor mediated apoptotic signaling. We identified and molecularly characterized a novel homolog of caspase 10 from black rockfish (Sebastes schlegelii) and designated as RfCasp10. The complete coding region of RfCasp10 was found to consist of 1659 bps, encoding a 553 amino acid protein with a predicted molecular mass of 61.7 kDa. The characteristic caspase family domain architecture, including death effecter domains (DEDs), was clearly identified in RfCasp10. Moreover, the RfCasp10 gene was found to contain 13 exons. Our pairwise sequence alignment confirmed the prominent sequence similarity of RfCasp10 with its fish homologs, and phylogenetic reconstruction affirmed its homology and substantial evolutionary relationship with known caspases 10 similitudes, in particular with those of teleosts. As detected by qPCR, RfCasp10 was markedly expressed in blood tissues under physiological conditions, whereas its expression was found to be upregulated under pathogenic stress, elicited by Streptococcus iniae and polyinosinic:polycytidylic acid in blood, liver, and spleen tissues. Collectively, our study suggests the plausible elicitation of RfCasp10 mediated apoptosis in immune relevant tissues of black rockfish as a host immune response to a bacterial or viral infection.