MAPKKK15 gene from shrimp Litopenaeus vannamei is transcribed in larva development stages and contributes to WSSV pathogenesis

Abstract

MAPKKK15 is a member of the mitogen-activated protein kinase kinase kinase (MAPKKK) family, which plays an important role in multiple biological progresses triggered by cellular stresses. In this study, a new homolog of MAPKKK15 has been cloned and identified from shrimp Litopenaeus vannamei (named as LvMAPKKK15). The full length of LvMAPKKK15 transcript was 4597 bp, including a 4317 bp open reading frame (ORF) that encoded a putative protein of 1438 amino acids. LvMAPKKK15 was abundantly expressed at early development stages with the highest transcriptional level in P12 stage. In adult shrimp, tissue distribution showed that LvMAPKKK15 was highly expressed in eyestalk, nerve and hemocytes. Besides, the induced transcription of LvMAPKKK15 could respond to the challenges of Poly (I: C) and white spot syndrome virus (WSSV). RNAi-mediated knockdown of LvMAPKKK15 caused shrimp less sensitive to WSSV infection, manifested by lessened virus loads, higher survival rate and higher transcription levels of anti-viral factors LvVagos. The results were further supported by the dual-luciferase reporter assays that the LvMAPKKK15 was able to up-regulate the promoter activities of several WSSV immediate early (IE) genes, but suppress the promoter activities of LvVago1–5 in vitro of cells. Together, these results suggested that LvMAPKKK15 was transcribed in larva development stages and played a role during WSSV pathogenesis.