Analysis of Expression, Cellular Localization, and Function of Three Inhibitors of Apoptosis (IAPs) from Litopenaeus vannamei during WSSV Infection and in Regulation of Antimicrobial Peptide Genes (AMPs)

Abstract

Inhibitors of apoptosis (IAPs) play important roles in apoptosis and NF-κB activation. In this study, we cloned and characterized three IAPs (LvIAP1-3) from the Pacific white shrimp, Litopenaeusvannamei . LvIAP1-3 proteins shared signature domains and exhibited significant similarities with other IAP family proteins. The tissue distributions of LvIAP1-3 were studied. The expression of LvIAP1-3 was induced in the muscle after white spot syndrome virus (WSSV) infection. LvIAP1 expression in the gill, hemocytes, hepatopancreas, and intestine was responsive to WSSV and Vibrio alginolyticus infections. LvIAP2 expression in the gill, hemocytes, and hepatopancreas was also responsive to WSSV infection. The expression of LvIAP3 in the gill, hemocytes, and intestine was reduced after V . alginolyticus infection. When overexpressed in Drosophila S2 cells, GFP labeled-LvIAP2 was distributed in the cytoplasm and appeared as speck-like aggregates in the nucleus. Both LvIAP1 and LvIAP3 were widely distributed throughout the cytoplasm and nucleus. The expression of LvIAP1, LvIAP2, and LvIAP3 was significantly knocked down by dsRNA-mediated gene silencing. In the gill of LvIAP1- or LvIAP3-silenced shrimp, the expression of WSSV VP28 was significantly higher than that of the dsGFP control group, suggesting that LvIAP1 and LvIAP3 may play protective roles in host defense against WSSV infection. Intriguingly, the LvIAP2-silenced shrimp all died within 48 hours after dsLvIAP2 injection. In the hemocytes of LvIAP2-silenced shrimps, the expression of antimicrobial peptide genes (AMPs), including Penaeidins, lysozyme, crustins, Vibrio penaeicidae-induced cysteine and proline-rich peptides (VICPs), was significantly downregulated, while the expression of anti-lipopolysaccharide factors (ALFs) was upregulated. Moreover, LvIAP2 activated the promoters of the NF-κB pathway-controlled AMPs, such as shrimp Penaeidins and Drosophila drosomycin and attacin A, in Drosophila S2 cells. Taken together, these results reveal that LvIAP1 and LvIAP3 might participate in the host defense against WSSV infection, and LvIAP2 might be involved in the regulation of shrimp AMPs.

Gene expression profiling in gill tissues of White spot syndrome virus infected black tiger shrimp Penaeus monodon by DNA microarray

“…vannamei were shown to be up-regulated post infection suggesting protective roles of IAPs in shrimp defense against WSSV infection [34]. In the present study, by microarray analysis we observed IAP to be down-regulated at initial stages (6 and 24 h) of WSSV infection and subsequently up-regulated from 48 hpi.…”

Inhibitor of apoptosis‐1 gene as a potential target for pest control and its involvement in immune regulation during fungal infection

“…24 Similarly, characterization of the three IAP genes in the Pacific white shrimp, Litopenaeus vannamei revealed their differential contributions to responding to white spot syndrome virus (WSSV) infection and expression of antimicrobial peptides. 25 Our results revealed that LmIAP1 also regulates antimicrobial peptide expression in response to fungal infection, with RNAi-mediated knockdown of LmIAP1 resulting in decreased transcription of antimicrobial peptides in the locust fat body after fungal infection, suggesting that LmIAP1 could be involve in humoral immunity to fungal infection. wileyonlinelibrary.com/journal/ps Apart from the fat body, hemocytes are other crucial insect immune-mediating tissues that function in cellular immunity.…”

“…RNAi‐mediated knockdown of this gene resulted in a reduced ability of the insect to induce expression of antimicrobial peptides in response to bacterial pathogens, and increased the susceptibility of the insect to infection by Gram‐negative bacteria . Similarly, characterization of the three IAP genes in the Pacific white shrimp, Litopenaeus vannamei revealed their differential contributions to responding to white spot syndrome virus (WSSV) infection and expression of antimicrobial peptides . Our results revealed that LmIAP1 also regulates antimicrobial peptide expression in response to fungal infection, with RNAi‐mediated knockdown of LmIAP1 resulting in decreased transcription of antimicrobial peptides in the locust fat body after fungal infection, suggesting that LmIAP1 could be involve in humoral immunity to fungal infection.…”

Inhibition of Apoptotic Pathways in Cancer

“…27 IAP proteinlerinde BIR domainine ek olarak Nterminal kaspaz organize edici bölge [caspase recruitment domain (CARD)] ve TRAF1 ile TRAF2'nin düzenlenmesine yardımcı ve TNF-αapoptotik sinyalizasyonunu inhibe eden ubikitin ligaz aktivitesinden sorumlu RING domaini de yer almaktadır. 28 Bugüne kadar insanlarda sekiz farklı IAP proteini tanımlanmıştır. Bu proteinler; nöronal apoptoz inhibe edici protein, hücresel apoptoz proteini inhibitörü-1 (c-IAP1), hücresel apoptoz proteini inhibitörü -2 (c-IAP2), apoptoz proteninin X'e bağlı inhibitörü (XIAP), baculovirus IAP tekrar (BIR) domaini-6 (Apollon), Livin, ILP-2 ve BIR domaini-5 (Survivin) olarak belirlenmiştir.…”