Molecular isolation and characterizationof tumor necrosis factor (tnf) geneof macrobrachium rosenbergii

Abstract

The tumor necrosis factor (TNF) is a cytokine that plays important roles in various physiological pathways, including inflammation and immune responses to microbial infections in vertebrates. TNF functions by binding to tumor necrosis factor receptor (TNFR) and initiating the signaling cascade to activate the NF-κB pathway and activator protein 1 (AP-1) pathway, which are required for the expression of pro-inflammatory cytokines. However, the role of TNF in immune responses in invertebrates remains largely unknown. Therefore, in this study, the full-length TNF gene of Macrobrachium rosenbergii (MrTNF) was isolated and characterized, then the expression of MrTNF in response to Aeromonas hydrophila and MrNV infections was investigated. The full-length cDNA of MrTNF was 1830 base pairs (bp), consisting of 5’ untranslated region (5’-UTR) of 396 bp and 3’-UTR of 54 bp. MrTNF contained an open reading frame (ORF) of 1380 bp encoding 459 amino acid residues. The MrTNF structure revealed the presence of a transmembrane domain at positions 21-43 and a conserved TNF domain at positions 324-446. The MrTNF protein revealed 91.88% identity with MnTNF from Macrobrachium nipponense. The expression level of MrTNF mRNA in healthy prawns exhibited high expression in the intestine, muscle, and stomach. MrTNF was significantly up-regulated in hemocyte, muscle, intestine, and stomach upon A. hydrophila infection. Furthermore, the expression level of MrTNF in muscle, gills, and hepatopancreas was significantly up-regulated upon MrNV challenge. These results indicated that MrTNF may play a crucial role in the innate immune system of freshwater crustaceans in response to bacterial and viral infections.

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