Serpin-type serine protease inhibitor mediates coelomocyte apoptosis in Apostichopus japonicus. Issue 104 (September 2020)

• Record Type: Journal Article
• Authors: Shi, Yuhong; Shao, Yina; Lv, Zhimeng; Li, Chenghua
• Is Part Of: Fish & shellfish immunology. Issue 104(2020)
• Page Start: 410
• Page End: 418
• Publication Date: 2020-09
• Subjects: Apostichopus japonicus -- Serine protease inhibitors -- Inhibitory activity -- Subcellular localization -- Apoptosis; Fishes -- Immunology -- Periodicals; Shellfish -- Immunology -- Periodicals; Poissons -- Immunologie -- Périodiques; Crustacés -- Immunologie -- Périodiques; 571.9617
• DOI: 10.1016/j.fsi.2020.06.006
• Languages: English
• ISSNs: 1050-4648

Abstract

Abstract: Serine protease inhibitors (SPIs, serpins) are a protein superfamily involved in almost all physiological processes in all organisms. In this study, a novel serpin was identified from Apostichopus japonicus ( Ajserpin ) by using high-throughput sequencing and RACE approaches. The full-length cDNA of Ajserpin was 1893 bp with a 5′-untranslated region (UTR) of 130 bp, a 3′-UTR of 587 bp, and an open reading frame of 1176 bp encoding a polypeptide of 391 amino acids with a deduced molecular weight of 43.8 kDa. Ajserpin shares the standard structure of SPI, including three β-sheets and eight α-helices. The deduced amino acid sequences of Ajserpin had no nuclear location signal and signal peptide structure. The phylogenetic tree and immunofluorescence showed that Ajserpin belonged to the clade B subfamily and was mainly located in the cytoplasm and nucleus. Sequence comparison and protein inhibition experiments showed that the active site (P1–P1' site) of Ajserpin was Arginine and Serine, which displayed inhibitory activity toward trypsin in a dose-dependent manner. Tissue distribution analysis showed that Ajserpin transcripts were constitutively expressed in all examined tissues with the peak in the body wall. Ajserpin mRNA transcripts could be induced in Vibrio splendidus -challenged sea cucumber or lipopolysaccharide-exposed coelomocytes. Furthermore, Ajserpin knockdown by small interfering RNAs could inhibit coelomocytes apoptosis. All our results revealed that Ajserpin might serve as an immune regulator in sea cucumber. Highlights: Complete cDNA sequence of serine protease inhibitors was identified in Apostichopus japonicus. Immunofluorescence showed Ajserpin was an intracellular protein belonging to the Clade B sub-family. Ajserpin mRNA transcripts could be induced by Vibrio splendidus challenge or LPS exposure. RAjserpin displayed inhibitory activity towards trypsin in a dose-dependent manner. Ajserpin knockdown by siRNA could accelerate the coelomocytes apoptosis.