A myeloid differentiation factor 88 gene from yellow catfish Pelteobagrus fulvidraco and its molecular characterization in response to polyriboinosinic polyribocytidylic acid and lipopolysaccharide challenge

Evolutionary and functional conservation of myeloid differentiation factor 88 (MyD88) in amphibian Xenopus tropicalis

As a universal adaptor used by most TLR members, the myeloid differentiation factor 88 (MyD88) plays essential roles in TLR-mediated inflammatory response of invertebrate and vertebrate animals, and functional features of MyD88 remain largely unknown in amphibians. In this study, a MyD88 gene named Xt-MyD88 was characterized in the Western clawed frog (Xenopus tropicalis). Xt-MyD88 and MyD88 in other species of vertebrates share similar structural characteristics, genomic structures, and flanking genes, suggesting that MyD88 is structurally conserved in different phyla of vertebrates ranging from fish to mammals. Moreover, Xt-MyD88 was widely expressed in different organs/tissues, and was induced by poly(I:C) in spleen, kidney, and liver. Importantly, overexpression of Xt-MyD88 triggered a marked activation of both NF-κB promoter and interferon-stimulated response elements (ISREs), implying that it may be play important roles in inflammatory responses of amphibians. The research represents the first characterization on the immune functions of amphibian MyD88, and reveals considerable functional conservation of MyD88 in early tetrapods.

Molecular characterization and expression analyses of five genes involved in the MyD88-dependent pathway of yellow catfish (Pelteobagrus fulvidraco) responding to challenge of Aeromonas hydrophila

MyD88-dependent pathway mediated by Toll-like receptor is one of the vital ways activating immune responses. In order to identify the role of MyD88-dependent signaling pathway in yellow catfish, the Pf_MyD88, Pf_IRAK4, Pf_IRAK1, Pf_TRAF6 and Pf_NFκB1 (p105) (Pf: abbreviation of Pelteobagrus fulvidraco) were cloned and characterized respectively. The Pf_MyD88, Pf_IRAK4, Pf_IRAK1 and Pf_TRAF6 were all highly conserved among species and showed the highest homology to that of Pangasianodon hypophthalmus. Pf_NFκB1 showed the highest homology to that of Ictalurus punetaus. All of the five genes showed similar expression patterns in various tissues, with the highest expression level in the liver. These genes also showed similar expression levels in different embryonic development stages, except Pf_IRAK4. The higher expression level was detected from fertilized eggs to 1 day post hatching (dph), lower expression from 3 dph to 30 dph. After stimulation of inactivated Aeromonas hydrophila, the mRNA expressions of Pf_MyD88, Pf_IRAK4, Pf_IRAK1, Pf_TRAF6 and Pf_NFκB1 were significantly increased at 24 h in the liver, spleen, head kidney and trunk kidney, suggesting that all the five genes were involved in the innate immune response of yellow catfish. These results showed that MyD88-dependent signaling pathway plays important roles for disease defensing in the innate immune response. Meanwhile, inactivated A. hydrophila can cause strong innate immune response, which provides theoretical bases for the application of inactivated vaccines in defense against bacterial diseases of teleost.

Characterization and functional analysis of a myeloid differentiation factor 88 in Ostrinia furnacalis Guenée larvae infected by Bacillus thuringiensis

Myeloid differentiation factor 88 (MyD88) is a pivotal adapter protein involved in activating nuclear factor NF-κB of the Toll pathway in insect innate immunity. MyD88 has been extensively studied in vertebrates and Drosophila. However, the information ascribed to MyD88 in Lepidoptera is scarce. In the present study, an Ostrinia furnacalis MyD88 (OfMyD88) cDNA was cloned and functionally characterized (GenBank accession no. MN906311). The complete cDNA sequence of OfMyD88 is 804 bp, and contains a 630 bp open reading frame encoding 209 amino acid residues. OfMyD88 has the death domain (DD), an intermediate domain, and the Toll/interleukin 1 receptor (TIR) domain. OfMyD88 was widely expressed in immune-related tissues such as hemocytes, fat body, midgut, and integument, with the highest expression level in hemocytes, and the lowest expression level in integument. To clarify the immune function of MyD88, O. furnacalis larvae were challenged with Bacillus thuringiensis (Bt) through feeding. Bt oral infection had significantly up-regulated the expression of OfMyD88 and immune genes, including PPO2 (prophenoloxidase 2), Attacin, Gloverin, Cecropin, Moricin, GRP3 (β-1, 3-Glucan recognition protein 3), and Lysozyme, and increased the activities of PO and lysozyme in hemolymph of O. furnacalis larvae. Knockdown of OfMyD88 by RNA interference suppressed the expression levels of immune related genes, but not PPO2 in the larvae orally infected with Bt, suggesting that OfMyD88 is involved in defending against Bt invasion through the Toll signaling pathway, but does not affect the PPO expression in O. furnacalis larvae.

Function of low ADARB1 expression in lung adenocarcinoma

Adenosine deaminase RNA-specific B1 (ADARB1), an adenosine-to-inosine (A-to-I) RNA-editing enzyme, has been found to play an essential role in the development of cancer. However, the specific function of ADARB1 in lung cancer, especially in lung adenocarcinoma (LUAD), is still not fully understood and requires further study. In our study, integrative bioinformatics were used to analyze the detailed function of ADARB1 in LUAD. By conducting bioinformatics analyses of several public databases, such as Gene Expression Profiling Interactive Analysis (GEPIA), GE-mini, and Oncomine, we found significantly decreased ADARB1 expression in LUAD cells and tissues. Moreover, RT-PCR and Western blot showed lower ADARB1 expression in H358 and A549 LUAD cells compared to human bronchial epithelial Beas-2B cells. Wound Healing Assay indicated that knockdown ADARB1 could promote LUAD cell metastasis. By using the Kaplan-Meier Plotter tool, we found that downregulation of ADARB1 was related to shorter first progression (FP), overall survival time (OS) and post-progression survival time (PPS). The relevant clinical data acquired from the Wanderer database indicated that the expression and methylation values of ADARB1 were significantly associated with the clinical characteristics of LUAD. Using DNA methylation inhibitor, we found DNMT inhibitor 5-aza-2-deoxycytidine (5-azaD) could promote the expression of ADARB1 and reverse the inhibition effect of ADARB1 in migration. In addition, functional enrichment analysis of ADARB1-associated coexpression genes was further conducted. Our investigation demonstrated that low levels of ADARB1 were specifically found in LUAD, and this gene might be a potential target in the diagnostic and prognostic evaluation of LUAD patients.