Expression, Purification, and Characterization of Anti-Zika virus Envelope Protein: Polyclonal and Chicken-Derived Single Chain Variable Fragment Antibodies

Zika virus (ZIKV) is a new and emerging virus that has caused outbreaks worldwide. The virus has been linked to congenital neurological malformations in neonates and Guillain-Barré syndrome in adults. Currently there are no effective vaccines available. As a result, there is a great need for ZIKV treatment. In this study, we developed single chain variable fragment (scFv) antibodies that target the ZIKV envelope protein using phage display technology. We first induced an immune response in white leghorn laying hens against the ZIKV envelope (E) protein. Chickens were immunized and polyclonal immunoglobulin yolk (IgY) antibodies were extracted from egg yolks. A high-level titer of anti-ZIKV_E IgY antibodies was detected using enzyme-linked immunosorbent assay (ELISA) after the third immunization. The titer persisted for at least 9 weeks. We constructed two antibody libraries that contained 5.3 × 10⁶ and 4.5 × 10⁶ transformants. After biopanning, an ELISA phage assay confirmed the enrichment of specific clones. We randomly selected 26 clones that expressed ZIKV scFv antibodies and classified them into two groups, short-linker and long-linker. Of these, four showed specific binding activities toward ZIKV_E proteins. These data suggest that the polyclonal and monoclonal scFv antibodies have the diagnostic or therapeutic potential for ZIKV.

Simultaneous separation of taxon-specific crystallins from Mule duck and characterization of their enzymatic activities and structures

Methods to obtain pure proteins in large amounts are indispensible in protein research. We report here a large-scale/simultaneous isolation of taxon-specific crystallins (ɛ- and δ-crystallin) from the eye lenses of Mule duck. We also investigate the compositions, enzymatic activities, and structures of these purified taxon-specific proteins. A relatively mild method of ion-exchange chromatography was developed to fractionate ɛ-crystallin and δ-crystallin in large amount, ca. ∼6.60mg/g-lens and ∼41.0mg/g-lens, respectively. Both crystallins were identified by electrophoresis, HPLC, and MALDI-TOF-MS. ɛ-Crystallin, with native composition of M_r 142kDa, consisted of two subunits of 35kDa and 36kDa, while δ-Crystallin, with native molecular mass of 200kDa, comprised single subunit of M_r ∼50kDa. Both ɛ- and δ-crystallin were tetramers. The former showed lactate dehydrogenase (LDH) activity, while the latter appeared slightly active in an argininosuccinate lyase (ASL) assay. Raman spectroscopic results indicated that the secondary structures of ɛ- and δ-crystallin were predominantly α-helix as evidenced by the vibrational stretching of amide III over 1260cm^-1 and amide I at 1255cm^-1, in greatly contrast to the anti-parallel β-sheet of α- and β-crystallin as demonstrated by amide III at 1238cm^-1 and amide I at 1672cm^-1. The microenvironments of aromatic amino acids and the status of thiol groups also vary in different crystallins. The compositions, enzyme activities, and structures of the ɛ- and δ-crystalline of Mule duck are different from those of Muscovy duck (Cairina moschata) or Kaiya duck (Anas Platyrhynchos var. domestica), which reflect faithfully species specificity.

Comparison of immunomodulatory functions of three peptides from the chicken bursa of Fabricius

The bursa of Fabricius (BF) is the acknowledged central humoral immune organ unique to birds which plays important roles in B cell development and antibody production. Little information on immunomodulatory functions of BF is reported, except for several reported active bursal-derived peptides. Three peptides were identified and characterized from BF through RP-HPLC and MADIL-TOF methods. They are named as bursal peptide (BP)-I, BP-II, BP-III. These peptides promoted CFU pre-B formation and decreased PU.1 expression. The different immunomodulatory activities of these three bursal peptides on antibody and cytokine productions were verified by the immunization comparative experiment. The results showed the three bursal peptides enhanced AIV-specific antibody and cytokine production, T-cell immunophenotyping at reachable concentrations. These results indicate the important orientations for the comprehensive understanding of the humoral central immune system, and provide a novel insight on new experimental reagents for immuno-adjuvant or immunopharmacological.

Effect of protein hydrolizates on growth kinetics and aminopeptidase activities of some Bifidobacterium species

This study evaluated the effect of a new hydrolizate from poultry feathers on growth kinetics and aminopeptidase activities of eight bifidobacteria compared with common peptones. The growth kinetics results suggest that the experimental hydrolizate could be a cheaper medium ingredient without affecting the modulation of common aminopeptidase activities.

Cross-species association of quail invariant chain with chicken and mouse MHC II molecules

There are different degrees of similarity among vertebrate invariant chains (Ii). The aim of this study was to determine the relationship between quail and other vertebrate Ii MHC class II molecules. The two quail Ii isoforms (qIi-1, qIi-2) were cloned by RACE, and qRT-PCR analysis of different organs showed that their expression levels were positively correlated with MHC II gene (B-LB) transcription levels. Confocal microscopy indicated that quail full-length Ii co-localized with MHC II of quail, chicken or mouse in 293FT cells co-transfected with both genes. Immunoprecipitation and western blotting further indicated that these aggregates corresponded to polymers of Ii and MHC class II molecules. This cross-species molecular association of quail Ii with chicken and mouse MHC II suggests that Ii molecules have a high structural and functional similarity and may thereby be used as potential immune carriers across species.

Avian lipocalin expression in chickens following Escherichia coli infection and inhibition of avian pathogenic Escherichia coli growth by Ex-FABP

Avian pathogenic Escherichia coli (APEC) causes respiratory disease and sepsis in poultry. To persist in its host, E. coli requires essential nutrients including iron. Since iron is limited in extra-intestinal tissues, E. coli produces siderophores, small molecules with high affinity for ferric iron, to sequester this essential nutrient. To counter bacterial siderophore systems, mammalian hosts secrete siderocalin (also called lipocalin 2 or NGAL), which binds ferric-siderophore complexes rendering them unavailable to bacteria. In humans and mice, siderocalin is known to play a role in primary defense against bacterial infections. In poultry, 4 proteins display homology to the human NGAL (CALβ, CALγ, Ggal-C8GC and Ex-FABP). The function and expression of the genes coding for these 4 proteins during infection by APEC is still unknown. Expression levels of these genes were determined by quantitative RT-PCR using RNA extracted from lungs, livers and spleens of healthy 3-week-old chickens and chickens infected with APEC. The gene coding for Ex-FABP was overexpressed in all organs tested. It was significantly more overexpressed in the lungs and liver than in the spleen (37.3 and 27.3 times versus 11.5 times, respectively). The genes coding for Calβ and Calγ were also found significantly overexpressed in the liver (27 and 8.2 times, respectively). To confirm the function of Ex-FABP as a siderocalin, the gene coding for this protein was cloned in an expression vector and the protein was purified. In vitro growth inhibition of E. coli strains by Ex-FABP was assayed in parallel with growth inhibition caused by human siderocalin. Purified Ex-FABP inhibited growth of E. coli K-12, which only produces the siderophore enterobactin. However, E. coli strains producing pathogen-associated siderophores including salmochelins (glucosylated enterobactin), aerobactin and yersiniabactin grew normally in the presence of Ex-FABP. These results indicate that Ex-FABP is an avian siderocalin with a siderophore-binding activity similar to that of human siderocalin and that pathogen-specific siderophores are required by APEC to overcome this innate defense protein in poultry.

Isolation, modulatory functions on murine B cell development and antigen-specific immune responses of BP11, a novel peptide from the chicken bursa of Fabricius

The bursa of Fabricius (BF) is the central humoral immune organ unique to birds which plays important roles in B lymphocyte differentiation. Here, a new bursal peptide (BP11) with the amino acid sequence DVAGKLPDNRT was identified and characterized from BF. It was proved that BP11 promoted CFU pre-B formation, and regulated B cell differentiation, including increase the percentage of immature and mature B cells in BM cells co-cultured with IL-7. BP11 also exerted immunomodulatory function on antigen-specific immune responses in BALB/c mice immunized with inactivated influence virus (AIV, H9N2 subtype) vaccine, including enhancing AIV-specific antibody and cytokine production. Furthermore, it was noteworthy that BP11 stimulated antibody productions and potentiates the Th1 and Th2-type immune responses in dose-dependent manner in chicken. These results suggested that BP11 might be highly relevant for the development of avian immune system.

Characterization and immunomodulatory function comparison of various bursal-derived peptides isolated from the humoral central immune organ

The bursa of Fabricius (BF) is the acknowledged central immune organ, which is important to the B cell differentiation and antibody production. However, due to difficult purification, the immunomodulatory peptides from BF were little reported. In this study, the extract samples of BF were taken to a chromatographic analysis by RP-HPLC. Five novel low molecular weight peptides were isolated from BF, with amino acid sequences of YEYAY, RMYEE, GPPAT, AGCCNG, and RRL, and named as Bursal pentapeptide (BPP)-III, -IV, -V, and Bursal hexapeptide (BHP), and Bursal tripeptide (BTP), respectively. BSP-I, BSP-II, BPP-I and BPP-II are recently reported to be the bursal-derived bioactive peptides. In this paper, we analyzed the chemical formula and characteristics of these nine bursal-derived peptides. The immunization comparative experiment verified the different immunomodulatory activity of these nine bursal peptides on antibody and cytokine productions. Furthermore, the results showed that at reachable concentrations, BPP-II and BPP-I induced antibody productions, lymphocyte viabilities and cytokine responses in different dose-dependent manner in the immunized mice model, respectively. These results provided important orientations for the comprehensively understanding and study of the humoral central immune system of human, and provided a novel insight on the treatment of serious disease and immune improvement of human.

Isolation, antiproliferation on tumor cell and immunomodulatory activity of BSP-I, a novel bursal peptide from chicken humoral immune system

The bursa of Fabricius (BF) is acknowledged as central humoral immune organ unique to birds. Our purpose was to identify the potential function of a novel bursal-derived bioactive peptide. A bursal septpeptide (BSP-I), EPASGMM, first isolated from BF, reduced MCF and Hela tumor cells proliferation, and enhanced antitumor factor p53 luciferase activity and protein expression. Further, we found the significantly immune inducing function of BSP-I on antigen-specific immune response in BALB/c mice intraperitoneally immunized with inactivated avian influence virus (AIV, H(9)N(2) subtype) vaccine, including of enhancing the antibody (IgG, the isotypes IgG1 and IgG2a) production, and stimulating cytokines IL-4 and IFN-γ level, and inducing T cell immunophenotyping and lymphocyte proliferation. These results suggested that as the bioactive peptide from avian humoral immune system, various biological function of BSP-I may have far-reaching implication on immune system significance, which might provide novel insight on linking between humoral immune system and development of effective immunotherapeutic strategies for treating human cancers diseases.

A novel disulfide-rich protein motif from avian eggshell membranes

Under the shell of a chicken egg are two opposed proteinaceous disulfide-rich membranes. They are fabricated in the avian oviduct using fibers formed from proteins that are extensively coupled by irreversible lysine-derived crosslinks. The intractability of these eggshell membranes (ESM) has slowed their characterization and their protein composition remains uncertain. In this work, reductive alkylation of ESM followed by proteolytic digestion led to the identification of a cysteine rich ESM protein (abbreviated CREMP) that was similar to spore coat protein SP75 from cellular slime molds. Analysis of the cysteine repeats in partial sequences of CREMP reveals runs of remarkably repetitive patterns. Module a contains a C-X(4)-C-X(5)-C-X(8)-C-X(6) pattern (where X represents intervening non-cysteine residues). These inter-cysteine amino acid residues are also strikingly conserved. The evolutionarily-related module b has the same cysteine spacing as a, but has 11 amino acid residues at its C-terminus. Different stretches of CREMP sequences in chicken genomic DNA fragments show diverse repeat patterns: e.g. all a modules; an alternation of a-b modules; or an a-b-b arrangement. Comparable CREMP proteins are found in contigs of the zebra finch (Taeniopygia guttata) and in the oviparous green anole lizard (Anolis carolinensis). In all these cases the long runs of highly conserved modular repeats have evidently led to difficulties in the assembly of full length DNA sequences. Hence the number, and the amino acid lengths, of CREMP proteins are currently unknown. A 118 amino acid fragment (representing an a-b-a-b pattern) from a chicken oviduct EST library expressed in Escherichia coli is a well folded, highly anisotropic, protein with a large chemical shift dispersion in 2D solution NMR spectra. Structure is completely lost on reduction of the 8 disulfide bonds of this protein fragment. Finally, solid state NMR spectra suggest a surprising degree of order in intact ESM fibers.

Isolation and potential immunological characterization of TPSGLVY, a novel bursal septpeptide isolated from the bursa of Fabricius

The bursa of Fabricius is central immune organ unique to birds, and the extract is immunocompetent in stimulating B cell differentiation and enhancing antibody production. However, except for bursin, the active peptides from the bursa of Fabricius are little reported. In the paper, a novel bursal septpeptide (BSP-II) with the amino acids sequence of TPSGLVY was identified and similar to the MGC53864 protein of Gallus gallus. We investigated the effects of BSP-II on the immune response in terms of the antibodies titers (IgG1 and IgG2alpha), the levels of interferon-gamma and interleukin-4 cytokines, spleen cell lymphocyte proliferation, and the T-lymphocyte subtype composition. It was noteworthy that BSP-II potentiates the Th1 and Th2-type immune responses in dose-dependent manner. BSP-II had specific enhancing effects on the hybridoma SP2/0 cell proliferation at two different serum concentrations (20% and 5%), but had no connection with the dose of BSP-II. The antibody secreting level of hybridoma SP2/0 cells rose in 5% and 20% serum when the concentrations of BSP-II increased. Also, BSP-II had effect on the viabilities of tumor cells (Hela and SP2/0). All the results indicated that BSP-II was able to significantly induce various immune responses and involved in the cell viability of different tumor cell lines. Our observations implied that BSP-II might be a novel biological active factor from the bursa of Fabricius with immunomodulatory activities.

Near-infrared (NIR) dye-labeled RNAs identify binding of ZBP1 to the noncoding Y3-RNA

The analysis of protein-RNA association in vitro commonly involves radiolabeled in vitro transcribed RNAs. Nucleotides labeled with near-infrared (NIR) dyes provide promising alternatives for studying protein-RNA binding in vitro. However, it remained elusive whether random labeling of RNA probes by NIR dyes interferes with protein binding. Here, we demonstrate that infrared scanning allows the detection of randomly NIR-labeled RNA probes in the low femtomole range. The analyses of eight distinct protein-RNA complexes by electrophoretic mobility shift assay, filter binding, or UV crosslinking revealed that protein binding specificity remains unaffected by random NIR labeling. Accordingly, NIR probes allowed the rapid identification of the short noncoding Y3-RNA as a novel RNA target of ZBP1 (zipcode binding protein). Whereas binding of ZBP1 to the ACTB-zipcode and Y3 was exclusive, the protein formed a trimeric complex with the La protein and Y3. This was dissociated in the presence of Y5 RNA, resulting in the formation of ZBP1/Y3 and La/Y5 complexes. Hence, ZBP1 apparently resides in at least two distinct cellular RNPs: mRNA-containing mRNPs or Y3-containing yRNPs. In conclusion, our findings indicate that randomly labeled NIR probes provide a powerful tool for the rapid and sensitive analysis of protein-RNA binding in vitro. In contrast to radiolabeled RNAs, NIR probes remain stable for months, do not pose any safety considerations, and enable the significantly expedited analysis of experimental data due to fast read technologies available. The most prominent advantage of probes labeled by NIR dyes is the option to color-code distinct transcripts, allowing the unbiased identification of distinct protein-RNA complexes in one sample.

A new key neurohormone controlling reproduction, gonadotrophin-inhibitory hormone in birds: discovery, progress and prospects

In vertebrates, the neuropeptide control of gonadotrophin secretion is primarily through the stimulatory action of the hypothalamic decapeptide, gonadotrophin-releasing hormone (GnRH). Gonadal sex steroids and inhibin inhibit gonadotrophin secretion via feedback from the gonads, but a hypothalamic neuropeptide inhibiting gonadotrophin secretion was, until recently, unknown in vertebrates. In 2000, we discovered a novel hypothalamic dodecapeptide that directly inhibits gonadotrophin release in quail and termed it gonadotrophin-inhibitory hormone (GnIH). GnIH acts on the pituitary and GnRH neurones in the hypothalamus via a novel G-protein-coupled receptor for GnIH to inhibit gonadal development and maintenance by decreasing gonadotrophin release and synthesis. The pineal hormone melatonin is a key factor controlling GnIH neural function. GnIH occurs in the hypothalamus of several avian species and is considered to be a new key neurohormone inhibiting avian reproduction. Thus, the discovery of GnIH provides novel directions to investigate neuropeptide regulation of reproduction. This review summarises the discovery, progress and prospects of GnIH, a new key neurohormone controlling reproduction.

Purification, crystallization and preliminary X-ray diffraction studies on avian haemoglobin from pigeon (Columba livia)

Haemoglobin is a physiologically significant metalloprotein that is involved in the exchange of gases for sustaining life. The respiratory system of birds is unique and complex compared with that of mammals. Many investigations of avian haemoglobins have revealed the presence of inositol pentaphosphate (IP5), a principal allosteric effector that is involved in regulation of their function. Structural investigations of avian haemoglobins are presently not adequate to explain their function. Efforts have been made in this direction in order to understand the oxygen-binding affinity involved in adapting to hypoxia in avian haemoglobins. Fresh whole blood was collected from pigeon (Columba livia) and purified using a DEAE cellulose anion-exchange chromatographic column. Crystallization of pigeon haemoglobin was accomplished using the hanging-drop vapour-diffusion method using PEG 3350 as a precipitant in 50 mM sodium acetate buffer pH 5.5 with 1 M NaCl. Data collection was carried out using a MAR345 image-plate detector system. The crystals diffracted to 2 A resolution. Pigeon haemoglobin crystallizes in a triclinic space group, with two whole biological molecules in the asymmetric unit and with unit-cell parameters a = 55.005, b = 65.528, c = 104.370 A, alpha = 78.742, beta = 89.819, gamma = 65.320 degrees .

Biochemical properties of gastrokine-1 purified from chicken gizzard smooth muscle

The potential role and function of gastrokine-1 (GNK1) in smooth muscle cells is investigated in this work by first establishing a preparative protocol to obtain this native protein from freshly dissected chicken gizzard. Some unexpected biochemical properties of gastrokine-1 were deduced by producing specific polyclonal antibody against the purified protein. We focused on the F-actin interaction with gastrokine-1 and the potential role and function in smooth muscle contractile properties.

Background

GNK1 is thought to provide mucosal protection in the superficial gastric epithelium. However, the actual role of gastrokine-1 with regards to its known decreased expression in gastric cancer is still unknown. Recently, trefoil factors (TFF) were reported to have important roles in gastric epithelial regeneration and cell turnover, and could be involved in GNK1 interactions. The aim of this study was to evaluate the role and function of GNK1 in smooth muscle cells.

Methodology/Principal Findings

From fresh chicken gizzard smooth muscle, an original purification procedure was used to purify a heat soluble 20 kDa protein that was sequenced and found to correspond to the gastrokine-1 protein sequence containing one BRICHOS domain and at least two or possibly three transmembrane regions. The purified protein was used to produce polyclonal antibody and highlighted the smooth muscle cell distribution and F-actin association of GNK1 through a few different methods.

Conclusion/Significance

Altogether our data illustrate a broader distribution of gastrokine-1 in smooth muscle than only in the gastrointestinal epithelium, and the specific interaction with F-actin highlights and suggests a new role and function of GNK1 within smooth muscle cells. A potential role via TFF interaction in cell-cell adhesion and assembly of actin stress fibres is discussed.

Vertebrate and invertebrate carotenoid-binding proteins

In invertebrates and vertebrates, carotenoids are ubiquitous colorants, antioxidants, and provitamin A compounds that must be absorbed from dietary sources and transported to target tissues where they are taken up and stabilized to perform their physiological functions. These processes occur in a specific and regulated manner mediated by high-affinity carotenoid-binding proteins. In this mini-review, we examine the published literature on carotenoid-binding proteins in vertebrate and invertebrate systems, and we report our initial purification and characterization of a novel lutein-binding protein isolated from liver of Japanese quail (Coturnix japonica).

Neuropeptide Y-family receptors Y6 and Y7 in chicken. Cloning, pharmacological characterization, tissue distribution and conserved synteny with human chromosome region

The peptides of the neuropeptide Y (NPY) family exert their functions, including regulation of appetite and circadian rhythm, by binding to G-protein coupled receptors. Mammals have five subtypes, named Y1, Y2, Y4, Y5 and Y6, and recently Y7 has been discovered in fish and amphibians. In chicken we have previously characterized the first four subtypes and here we describe Y6 and Y7. The genes for Y6 and Y7 are located 1 megabase apart on chromosome 13, which displays conserved synteny with human chromosome 5 that harbours the Y6 gene. The porcine PYY radioligand bound the chicken Y6 receptor with a K(d) of 0.80 +/- 0.36 nm. No functional coupling was demonstrated. The Y6 mRNA is expressed in hypothalamus, gastrointestinal tract and adipose tissue. Porcine PYY bound chicken Y7 with a K(d) of 0.14 +/- 0.01 nm (mean +/- SEM), whereas chicken PYY surprisingly had a much lower affinity, with a Ki of 41 nm, perhaps as a result of its additional amino acid at the N terminus. Truncated peptide fragments had greatly reduced affinity for Y7, in agreement with its closest relative, Y2, in chicken and fish, but in contrast to Y2 in mammals. This suggests that in mammals Y2 has only recently acquired the ability to bind truncated PYY. Chicken Y7 has a much more restricted tissue distribution than other subtypes and was only detected in adrenal gland. Y7 seems to have been lost in mammals. The physiological roles of Y6 and Y7 remain to be identified, but our phylogenetic and chromosomal analyses support the ancient origin of these Y receptor genes by chromosome duplications in an early (pregnathostome) vertebrate ancestor.

Analysis of chicken serum proteome and differential protein expression during development in single-comb White Leghorn hens

Serum is believed to harbor thousands of distinct proteins that are either actively secreted or leak from various blood cells or tissues. Exploring protein composition in serum may accelerate the discovery of novel protein biomarkers for specific economic traits in livestock species. This study analyzed serum protein composition to establish a 2-DE reference map, and monitored protein dynamics of single-comb White Leghorn hens at 8, 19 and 23 weeks after hatching. A total of 119 CBB-stained and 315 silver-stained serum protein spots were analyzed by MALDI-TOF MS. Of these, 98 CBB-stained and 94 silver-stained protein spots were significantly matched to existing chicken proteins. The identified spots represented 30 distinctive proteins in the serum of laying hens. To compare protein expression during development, expression levels of 47 protein spots were quantified by relative spot volume with Melanie 3 software. Ten protein spots increased and 3 protein spots decreased as hen age increased. Previous research has suggested that some of these proteins play critical roles in egg production. The differentially expressed proteins with unknown identities will be valuable candidates for further explorations of their roles in egg production of laying hens.

The novel avian protein, AWAK, contains multiple domains with homology to protease inhibitory modules

We report the purification of a 3.5kDa peptide with antimicrobial activity from the mucosa and epithelial cells of chicken intestine. The peptide contains a pattern of cysteines characteristic of a whey acidic protein (WAP) domain and was identified as the carboxy terminal fragment of a novel 767 amino acid avian protein which has a proposed molecular weight of 81kDa. Using the conserved domain database (CDD) we identified this 81kDa protein to contain multiple amino acid motifs with homology to WAP domains and an amino acid motif with homology to a Kunitz proteinase inhibitor domain. We propose to call this avian protein AWAK (Avian WAP motif containing, Kunitz domain containing). The presence of WAP and Kunitz modules suggests that AWAK has proteinase inhibitor activity. RT-PCR analyses demonstrated expression of the AWAK gene in the chicken intestine.

Antimicrobial proteins in chicken reproductive system

Antimicrobial activity was detected in the ovary and oviduct tissues of healthy mature White Leghorn hens, Gallus gallus. Two antimicrobial proteins were purified to homogeneity using acid extraction followed by multiple steps of chromatography and the pure proteins were further characterized biochemically. Peptide mixtures obtained after enzymatic digestion of the chicken antimicrobial proteins were analyzed using peptide mass fingerprinting and partial sequencing by tandem nanoelectrospray mass spectrometry and the proteins were identified as histones H1 and H2B. Chicken histone antimicrobial proteins were active against both Gram-positive and Gram-negative bacteria. The abundance of these proteins in the reproductive tissues and their broad-spectrum antimicrobial nature may indicate their defensive role against pathogens during the follicle development in the ovary and egg formation in the oviduct. The discovery of antimicrobial histones in chicken reproductive system provides further evidence that histones may play a role in innate immunity against microorganisms in a wide range of animal species.

Molecular cloning and characterization of chicken lipopolysaccharide-induced TNF-alpha factor (LITAF)

The inflammatory response to parasites, bacteria, and viruses is mediated by multiple host factors. TNF-alpha is one of the most pleiotropic cytokines in mammals, but has yet to be identified in avian species. In the current study, we isolated a full-length cDNA encoding the chicken homologue of LPS-induced TNF-alpha factor (LITAF), transcription factor, with an open reading frame of 148 amino acids and a predicted molecular mass of 16.0kDa. Quantitative RT-PCR analysis showed that chicken LITAF mRNA was predominantly expressed in spleen and intestinal intraepithelial lymphocytes (IELs). LITAF mRNA levels were up-regulated following in vitro stimulation of macrophages for 4 h with Escherichia coli or Salmonella typhimurium endotoxin, and 18-48 h after treatment with Eimeria acervulina, E. maxima, or E. tenella, three causative agents of avian coccidiosis. LITAF mRNA was up-regulated by more than 700-fold in IELs isolated from E. maxima-infected birds. Purified recombinant LITAF protein expressed in E. coli or COS7 cells exhibited cytotoxic activity against chicken tumor cell lines in vitro, presumably through autocrine activation of TNF-alpha or its chicken homologue. This supposition was strengthened by the fact that treatment of chicken macrophages with recombinant LITAF induced the expression of TL1A (TNFSF 15), a member of the TNF ligand super family. We conclude that chicken LITAF may play an important role in the regulation of TNF-alpha gene expression during the course of coccidiosis or tumorigenesis.

Regulator of complement activation (RCA) locus in chicken: identification of chicken RCA gene cluster and functional RCA proteins

A 150-kb DNA fragment, which contains the gene of the chicken complement regulatory protein CREM (formerly named Cremp), was isolated from a microchromosome by screening bacterial artificial chromosome library. Within 100 kb of the cloned region, three complete genes encoding short consensus repeats (SCRs, motifs with tandemly arranged 60 aa) were identified by exon-trap method and 3'- or 5'-RACE. A chicken orthologue of the human gene 6-phosphofructo-2-kinase/fructose-2,6-biphosphatase 2, which exists in close proximity to the regulator of complement activation genes in humans and mice, was located near this chicken SCR gene cluster. Moreover, additional genes encoding SCR proteins appeared to be present in this region. Three distinct transcripts were detected in RNA samples from a variety of chicken organs and cell lines. Two novel genes named complement regulatory secretory protein of chicken (CRES) and complement regulatory GPI-anchored protein of chicken (CREG) besides CREM were identified by cloning corresponding cDNA. Based on the predicted primary structures and properties of the expressed molecules, CRES is a secretory protein, whereas CREG is a GPI-anchored membrane protein. CREG and CREM were protected host cells from chicken complement-mediated cytolysis. Likewise, a membrane-bound form of CRES, which was artificially generated, also protected host cells from chicken complement. Taken together, the chicken possesses an regulator of complement activation locus similar to those of the mammals, and the gene products function as complement regulators.

Churchill, a zinc finger transcriptional activator, regulates the transition between gastrulation and neurulation

Gastrulation generates mesoderm and endoderm from embryonic epiblast; soon after, the neural plate is established within the epiblast-both events require FGF signaling. We describe a zinc finger transcriptional activator, Churchill (ChCh), which acts as a switch between different roles of FGF. FGF induces ChCh slowly; this activates Smad-interacting-protein-1 (Sip1), which blocks further induction of the mesoderm markers brachyury and Tbx6L by FGF. ChCh is first expressed as cells stop migrating through the primitive streak, and we show that it regulates cell ingression. We propose a simple mechanism by which FGF sensitizes cells to BMP signals. These results reveal that neural induction requires cessation of mesoderm formation at the midline in addition to the decision between epidermis and neural plate.