S.D.N.K. Bathigea, b, Navaneethaiyer Umasuthana, b, G.I. Godahewaa, b, Ilson Whanga, b, Chul Kimc, Hae-Chul Parkd,*, Jehee Leea, b,*
a Department of Marine Life Sciences, School of Marine Biomedical Sciences, Jeju National University, Jeju Self-Governing Province 690-756, Republic of Korea
b Fish Vaccine Research Center, Jeju National University, Jeju Special Self-Governing Province 690-756, Republic of Korea
c Informatics Development & Management Group, Korea Institute of Oriental Medicine, 1672 Yuseongdae-ro, Yuseong-gu, Daejeon, 305-811, Korea
d Graduate School of Medicine, Korea University, Ansan, Gyeonggido 425-707, Republic of Korea
*Corresponding authors.
Abstract
Serine protease inhibitors (SERPINs) control cellular protease activity in order to maintain cellular homeostasis. The immune and inflammatory responses of invertebrate clade B SERPINs have not been widely reported. In the present study, three proteins with high similarity to clade B SERPINs, referred to as AbSERPIN-1, AbSERPIN-2 and AbSERPIN-3, were identified from disk abalone (Haliotis discus discus). While AbSERPIN-1 (399 aa) was of a typical size for this protein class, AbSERPIN-2 (506 aa) and AbSERPIN-3 (532 aa) were relatively larger. Bioinformatic analysis revealed the characteristic SERPIN domain in each AbSERPIN. In addition, the N-terminal region of both AbSERPIN-2 and AbSERPIN-3 contained a predicted low complexity region (LCR) and a signal peptide, suggesting that these proteins are secretory proteins and are, thus, novel peptides. Tertiary structural models of the AbSERPINs highlighted their structural and functional conservation. Ubiquitous expression of AbSERPIN transcripts was evaluated by quantitative real time PCR (qPCR) analysis in seven tissue types. AbSERPIN-1, AbSERPIN-2, and AbSERPIN-3 transcript levels were highest in mantle, hemocytes, and muscles, respectively. Temporal expression analysis revealed that AbSERPINs were significantly (P < 0.05) elevated in hemocytes during the early/middle stages following the injection of a bacterial pathogen (Vibrio parahaemolyticus or Listeria monocytogenes) or an immuno-stimulant (lipopolysaccharide). Moreover, mantle tissue injury led to significant changes in the temporal expression of AbSERPIN mRNA. Specifically, transcription of AbSERPIN-1 and AbSERPIN-3 was considerably up-regulated, while expression of AbSERPIN-2 was suppressed. These results suggest a potential role of AbSERPINs in response to pathogen invasion and tissue injury in disk abalone.
Keywords : Serine protease inhibitor (SERPIN); Haliotis discus discus; immune response; tissue injury