NF-κB signaling induces inductive expression of the downstream molecules and IgD gene in the freshwater carp, Catla catla

Toll-like receptors (TLRs) in innate immune system act as primary sensors in detecting the microbial components and activate their signaling cascades to induce NF-kappa B (nuclear factor NF-kappa B) towards the augmentation of immunoglobulin (Ig) synthesis. To gain insights into the efficacy of NF-kappa B pathway in immunoglobulin D (IgD) synthesis in the Indian Major CarpCatla catla,cloning and sequencing of TLR-signaling downstream molecules [TRAF3 (TNF receptor-associated factor 3), NEMO (nuclear factor-kappa B essential modulator), NF-kappa B and BAFF (B cell activating factor)] were performed by infecting the fish with pathogens. mRNA expression analysis of the downstream molecules and IgD showed significant up-regulation of these genes in kidney (P <= 0.001) as compared to spleen (P <= 0.05). To ascertain the role of NF-kappa B pathway in IgD synthesis, the primary cell culture of kidney and spleen in monolayer cell suspension was treated with NF-kappa B inhibitor (BAY 11-7082) and down-regulation of BAFF,NEMO, NF-kappa B, andIgDgene was observed. These results highlight the importance of NF-kappa B signaling pathway in augmenting theIgDgene expression in the freshwater carp,Catla catla.