Characterization of Chicken Tumor Necrosis Factor-alpha, a Long Missed Cytokine in Birds

Tumor necrosis factor-alpha (TNF-alpha) is a pleiotropic cytokine playing critical roles in host defense and acute and chronic inflammation. It has been described in fish, amphibians, and mammals but was considered to be absent in the avian genomes. Here, we report on the identification and functional characterization of the avian ortholog. The chicken TNF-alpha (chTNF-alpha) is encoded by a highly GC-rich gene, whose product shares with its mammalian counterpart 45% homology in the extracellular part displaying the characteristic TNF homology domain. Orthologs of chTNF-alpha were identified in the genomes of 12 additional avian species including Palaeognathae and Neognathae, and the synteny of the closely adjacent loci with mammalian TNF-alpha orthologs was demonstrated in the crow (Corvus cornix) genome. In addition to chTNF-alpha, we obtained full sequences for homologs of TNF-alpha receptors 1 and 2 (TNFR1, TNFR2). chTNF-a mRNA is strongly induced by lipopolysaccharide (LPS) stimulation of monocyte derived, splenic and bone marrow macrophages, and significantly upregulated in splenic tissue in response to i.v. LPS treatment. Activation of T-lymphocytes by TCR crosslinking induces chTNF-alpha expression in CD4(+) but not in CD8(+) cells. To gain insights into its biological activity, we generated recombinant chTNF-alpha in eukaryotic and prokaryotic expression systems. Both, the full-length cytokine and the extracellular domain rapidly induced an NF kappa B-luciferase reporter in stably transfected CEC-32 reporter cells. Collectively, these data provide strong evidence for the existence of a fully functional TNF-alpha/TNF-alpha receptor system in birds thus filling a gap in our understanding of the evolution of cytokine systems

Dazap2 modulates transcription driven by the Wnt effector TCF-4

A major outcome of the canonical Wnt/β-catenin-signalling pathway is the transcriptional activation of a specific set of target genes. A typical feature of the transcriptional response induced by Wnt signalling is the involvement of Tcf/Lef factors that function in the nucleus as the principal mediators of signalling. Vertebrate Tcf/Lef proteins perform two well-characterized functions: in association with β-catenin they activate gene expression, and in the absence of Wnt ligands they bind TLE/Groucho proteins to act as transcriptional repressors. Although the general characteristics of Tcf/Lef factors are well understood, the mechanisms that control their specific roles in various cellular backgrounds are much less defined. In this report we reveal that the evolutionary conserved Dazap2 protein functions as a TCF-4 interacting partner. We demonstrate that a short region proximal to the TCF-4 HMG box mediates the interaction and that all Tcf/Lef family members associate with Dazap2. Interestingly, knockdown of Dazap2 not only reduced the activity of Wnt signalling as measured by Tcf/β-catenin reporters but additionally altered the expression of Wnt-signalling target genes. Finally, chromatin immunoprecipitation studies indicate that Dazap2 modulates the affinity of TCF-4 for its DNA-recognition motif

Molecular characterization of the rare translocation t(3;10)(q26;q21) in an acute myeloid leukemia patient

Background: In acute myeloid leukemia (AML), the MDS1 and EVI1 complex locus - MECOM, also known as the ecotropic virus integration site 1 - EVI1, located in band 3q26, can be rearranged with a variety of partner chromosomes and partner genes. Here we report on a 57-year-old female with AML who presented with the rare translocation t(3;10) (q26;q21) involving the MECOM gene. Our aim was to identify the fusion partner on chromosome 10q21 and to characterize the precise nucleotide sequence of the chromosomal breakpoint. Methods: Cytogenetic and molecular-cytogenetic techniques, chromosome microdissection, next generation sequencing, long-range PCR and direct Sanger sequencing were used to map the chromosomal translocation. Results: Using a combination of cytogenetic and molecular approaches, we mapped the t(3;10)(q26;q21) to the single nucleotide level, revealing a fusion of the MECOM gene (3q26.2) and C10orf107 (10q21.2). Conclusions: The approach described here opens up new possibilities in characterizing acquired as well as congenital chromosomal aberrations. In addition, DNA sequences of chromosomal breakpoints may be a useful tool for unique molecular minimal residual disease target identification in acute leukemia patients

Full-length cDNAs from chicken bursal lymphocytes to facilitate gene function analysis.

A large number of cDNA inserts were sequenced from a high-quality library of chicken bursal lymphocyte cDNAs. Comparisons to public gene databases indicate that the cDNA collection represents more than 2,000 new, full-length transcripts. This resource defines the structure and the coding potential of a large fraction of B-cell specific and housekeeping genes whose function can be analyzed by disruption in the chicken DT40 B-cell line

Full-Length cDNAs from Chicken Bursal Lymphocytes to Facilitate Gene Function Analysis

A large number of cDNA inserts were sequenced from a high-quality library of chicken bursallymphocyte cDNAs. Comparisons to public gene databases indicate that the cDNA collectionrepresents more than 2,000 new, full-length transcripts. This resource defines the structure and the coding potential of a large fraction of B-cell specific and housekeeping genes whose function can be analyzed by disruption in the chicken DT40 B-cell line