Cytotoxic T-lymphocyte responses in cattle infected with bovine viral diarrhea virus

CRP1, a Drosophila nuclear protein that can catalyze decondensation of demembranated Xenopus sperm chromatin was cloned and its primary structure was deduced from cDNA sequence. Alignment of deduced amino acid sequence with published sequences of other proteins revealed strong homologies to Xenopus nucleoplasmin and NO38. CRP1 is encoded by one or several closely related genes found at a single locus, position 99A on the right arm of chromosome 3. CRP1 mRNA is expressed throughout Drosophila development; it is highest during oogenesis and early embryogenesis. mRNA levels correlate closely with levels of protein expression measured previously. Results of chemical crosslinking indicate that CRP1 is either tetrameric or pentameric; similar ambiguity was revealed by direct visualization using scanning transmission electron microscopy. Consistent with previously published results, parallel crosslinking studies of Xenopus nucleoplasmin suggested a pentameric structure. Scanning transmission electron microscopic examination after negative staining revealed that CRP1 and Xenopus nucleoplasmin are morphologically similar. CRP1 is able to substitute for nucleoplasmin in Xenopus egg extract-mediated sperm chromatin decondensation. In vitro, CRP1-induced decondensation is accompanied by direct binding of CRP1 to chromatin.     

Development of monkey C-reactive protein (CRP) assay methods

Monkey-specific C-reactive protein (CRP) assay methods (enzyme-linked immunosorbent assay (ELISA) and turbidimetric immunoassay (TIA)) were developed. The anti-monkey CRP serum was prepared by immunization of rabbits with the immune complex formed between the acute-phase serum from turpentine oil-inoculated monkeys and goat anti-human CRP serum. The specificity of the rabbit anti-monkey CRP serum was confirmed by immunoelectrophoresis and Western blotting. The purity of monkey CRP prepared by chromatography procedures was confirmed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). The serum CRP levels in nine normal monkeys, as measured by sandwich ELISA were ranged from 0.26 to 1.42 microg/ml (mean 0.71+/-0.37). The CRP levels in five acute-phase sera of turpentine oil-inoculated monkeys were 248-451 microg/ml (mean 371.2+/-73.8). This monkey-specific CRP assay method was found more sensitive than the human-specific CRP assay method in detecting monkey CRP by TIA.     

Molecular identification of a putative human hyaluronan synthase

To identify the putative mammalian hyaluronan synthase, we cloned a human cDNA that is related to the Streptococcus hyaluronan synthase (HasA) and the Xenopus developmental protein DG42 which has been shown to have chitin synthase activity. The cDNA, for which we propose the name Has2, encodes a novel protein with a predicted molecular mass of 63.6 kDa. Has2 shows 55% amino acid identity with Xenopus DG42 and 52% identity with the mouse HAS protein, another putative hyaluronan synthase recently reported by Itano and Kimata (Itano, N., and Kimata, K. (1996) J. Biol. Chem. 271, 9875-9878). The deduced primary structure revealed the presence of several hydrophobic stretches which can form multiple transmembrane domains. It also demonstrated the complete conservation of amino acid residues that are known to be critical for N-acetylglucosaminyltransferase activity of yeast chitin synthase. When the Has2 cDNA was transfected into human 293 and Chinese hamster ovary cells, the production of hyaluronan in the transfected cells increased up to 34- and 9-fold, respectively. Strong expression of Has2 mRNA was observed in exponentially proliferating human IMR-90 fibroblasts but not in growth-arrested IMR-90 cells. These results suggest that the Has2 protein is a crucial component of the human hyaluronan synthase system.     

Embryonic expression suggests an important role for CRP2/SmLIM in the developing cardiovascular system

Proteins of the LIM family are critical regulators of development and differentiation in various cell types. We have described the cloning of cysteine-rich protein 2/smooth muscle LIM protein (CRP2/SmLIM), a LIM-only protein expressed in differentiated vascular smooth muscle cells. As a first step toward understanding the potential functions of CRP2/SmLIM, we analyzed its expression after gastrulation in developing mice and compared the expression of CRP2/SmLIM with that of the other 2 members of the CRP subclass, CRP1 and CRP3/MLP. In situ hybridization in whole-mount and sectioned embryos showed that CRP2/SmLIM was expressed in the sinus venosus and the 2 cardiac chambers at embryonic day 9. Vascular expression of CRP2/SmLIM was first seen at embryonic day 10. At subsequent time points, CRP2/SmLIM expression decreased in the heart but remained high in the vasculature. CRP1 was expressed both in vascular and nonvascular tissues containing smooth muscle cells, whereas CRP3/MLP was expressed only in tissues containing striated muscle. These patterns of expression were maintained in the adult animal and suggest an important role for this gene family in the development of smooth and striated muscle.     

Apoptosis-specific protein (ASP) identified in apoptotic Xenopus thymus tumor cells

A novel apoptosis-specific protein (ASP) has recently been identified in the cytoplasm of apoptotic mammalian cells. This paper investigates whether ASP is found in Xenopus thymus tumor-derived lymphoid cell lines undergoing apoptosis and also in apoptotic, nontransformed splenocytes. Cultured Xenopus tumor lymphoid cells induced to undergo apoptosis by serum deprivation or treatment with the calcium ionophore, ionomycin, displayed altered morphology typical of apoptotic cells, as judged by flow cytometric light-scatter characteristics and by fluorescence microscopy of acridine-orange-stained cells. Flow cytometry of permeabilized cells and fluorescence microscopy of acetone-fixed cytospins revealed that apoptotic Xenopus tumor cells, especially those displaying loss or condensation of DNA, displayed increased expression of epitopes recognized by a rabbit polyclonal antibody against ASP. Flow cytometry confirmed that ASP is also expressed in splenocytes induced to apoptose by culture in ionomycin or following concanavalin A stimulation. No increased expression of ASP was seen when lymphoid tumor cells or splenocytes were induced into necrosis by overdose with the antifungal agent amphotericin B. Western blotting with antibody against ASP identified the emergence of several protein bands in cell lysates from apoptotic, but not necrotic, Xenopus tumor cells. The new and simple methodology for identifying apoptotic cells described here is likely to be of value to those studying immune system development and associated programmed cell death in Xenopus.     

Canine C-reactive protein (CRP) does not share common antigenicity with human CRP

Differences in antigenicity between human and canine C-reactive proteins were investigated by Western blotting analysis. It was confirmed that several commercial anti-human CRP sera reacted with canine CRP. However, 34 anti-canine CRP sera prepared by immunization of rabbits and goats with canine CRP all reacted with canine CRP but not with human CRP in either immunoelectrophoresis or Western blotting. Immunization with human CRP produced a cross-reacting antibody that reacted with canine CRP. Conversely, immunization with canine CRP did not produce a cross-reacting antibody that reacted with human CRP. These findings may be interpreted as showing that, while canine and human CRPs do not share common antigenicity, they do contain structurally similar antigenic determinants.     

Hydration of polyethylene glycol-grafted liposomes

In this report we describe the identification, cloning, and expression pattern of human cytokine-like factor 1 (hCLF-1) and the identification and cloning of its murine homologue. They were identified from expressed sequence tags using amino acid sequences from conserved regions of the cytokine type I receptor family. Human CLF-1 and murine CLF-1 shared 96% amino acid identity and significant homology with many cytokine type I receptors. CLF-1 is a secreted protein, suggesting that it is either a soluble subunit within a cytokine receptor complex, like the soluble form of the IL-6R alpha-chain, or a subunit of a multimeric cytokine, e.g., IL-12 p40. The highest levels of hCLF-1 mRNA were observed in lymph node, spleen, thymus, appendix, placenta, stomach, bone marrow, and fetal lung, with constitutive expression of CLF-1 mRNA detected in a human kidney fibroblastic cell line. In fibroblast primary cell cultures, CLF-1 mRNA was up-regulated by TNF-alpha, IL-6, and IFN-gamma. Western blot analysis of recombinant forms of hCLF-1 showed that the protein has the tendency to form covalently linked di- and tetramers. These results suggest that CLF-1 is a novel soluble cytokine receptor subunit or part of a novel cytokine complex, possibly playing a regulatory role in the immune system and during fetal development.     

The Orc4p and Orc5p subunits of the Xenopus and human origin recognition complex are related to Orc1p and Cdc6p

The location of origins of DNA replication within the Saccharomyces cerevisiae genome is primarily determined by the origin recognition complex (ORC) interacting with specific DNA sequences. The analogous situation in vertebrate cells is far less clear, although ORC subunits have been identified in several vertebrate organisms including Xenopus laevis. Monoclonal antibodies were raised against Xenopus Orc1p and used for single-step immunoaffinity purification of the entire ORC from an egg extract. Six polypeptides ( approximately 110, 68, 64, 48, 43, and 27 kDa) copurified with Xenopus Orc1p. Protein sequencing also showed the 64-kDa protein to be the previously identified Xenopus Orc2p. Microsequencing of the 43- and 48-kDa proteins that copurified with Orc1p and Orc2p led to their identification as the Orc4p and Orc5p subunits, respectively. Peptide sequences from the 43-kDa protein also allowed the isolation of cDNAs encoding the Xenopus, mouse, and human ORC4 subunits. Human ORC5 was also cloned; its sequence displayed extensive homology to both Drosophila and yeast ORC5. Surprisingly, comparison of the amino acid sequences of Orc1p, Orc4p, and Orc5p suggests that they are structurally related to each other and to the replication initiation protein, Cdc6p. Finally, we present the sequence of the putative Xenopus and human Orc3p.     

Immunologic recognition of a 25-amino acid repeat arrayed in tandem on a major antigen of Blastomyces dermatitidis

A 120-kD glycoprotein antigen abundantly expressed on Blastomyces dermatitidis yeasts is a target of cellular and humoral immune responses in human infection. To investigate the antigen and immune response more carefully at the molecular level, we screened an expression library from B. dermatitidis to identify clones that encode this antigen, designated WI-1. A 942-bp cDNA was isolated by immunologic screening with polyclonal, rabbit anti-WI-1 antiserum. Northern hybridization analysis showed that the cDNA hybridized to yeast message approximately equal to 3.9 kb. DNA and deduced protein sequence analysis of the clone demonstrated a 25-amino acid repeat arrayed in tandem, present in 4.5 copies near the 5' end, and rich in predicted antigenic epitopes. Further analysis showed strong homology in these tandem repeats with invasin, an adhesin of Yersiniae. Cloned cDNA was used to express a 30-kD fusion protein strongly recognized in western blots by rabbit anti-WI-1 antiserum, and by sera from all 35 blastomycosis patients studied. The fusion protein product of subcloned cDNA encoding only the tandem repeat also was strongly recognized in western blots by sera from the 35 blastomycosis patients, but not by sera from 10 histoplasmosis and 5 coccidioidomycosis patients. An antigen-inhibition radioimmunoassay showed that the tandem repeat alone completely eliminated rabbit and human anti-WI-1 antibody binding to radiolabeled native WI-1. From these results, we conclude that the 25-amino acid repeat of WI-1 displays an immunodominant B cell epitope, and that the carboxyl-terminus of the molecule exhibits an architecture that may promote adhesion of Blastomyces yeasts to host cells or extracellular matrix proteins and ultimately provide a clearer picture of the molecular pathogenesis of blastomycosis.     

Identification and characterization of a membrane protein (y+L amino acid transporter-1) that associates with 4F2hc to encode the amino acid transport activity y+L. A candidate gene for lysinuric protein intolerance

We have identified a new human cDNA (y+L amino acid transporter-1 (y+LAT-1)) that induces system y+L transport activity with 4F2hc (the surface antigen 4F2 heavy chain) in oocytes. Human y+LAT-1 is a new member of a family of polytopic transmembrane proteins that are homologous to the yeast high affinity methionine permease MUP1. Other members of this family, the Xenopus laevis IU12 and the human KIAA0245 cDNAs, also co-express amino acid transport activity with 4F2hc in oocytes, with characteristics that are compatible with those of systems L and y+L, respectively. y+LAT-1 protein forms a approximately 135-kDa, disulfide bond-dependent heterodimer with 4F2hc in oocytes, which upon reduction results in two protein bands of approximately 85 kDa (i.e. 4F2hc) and approximately 40 kDa (y+LAT-1). Mutation of the human 4F2hc residue cysteine 109 (Cys-109) to serine abolishes the formation of this heterodimer and drastically reduces the co-expressed transport activity. These data suggest that y+LAT-1 and other members of this family are different 4F2 light chain subunits, which associated with 4F2hc, constitute different amino acid transporters. Human y+LAT-1 mRNA is expressed in kidney > peripheral blood leukocytes > lung > placenta = spleen > small intestine. The human y+LAT-1 gene localizes at chromosome 14q11.2 (17cR approximately 374 kb from D14S1350), within the lysinuric protein intolerance (LPI) locus (Lauteala, T., Sistonen, P. , Savontaus, M. L., Mykkanen, J., Simell, J., Lukkarinen, M., Simmell, O., and Aula, P. (1997) Am. J. Hum. Genet. 60, 1479-1486). LPI is an inherited autosomal disease characterized by a defective dibasic amino acid transport in kidney, intestine, and other tissues. The pattern of expression of human y+LAT-1, its co-expressed transport activity with 4F2hc, and its chromosomal location within the LPI locus, suggest y+LAT-1 as a candidate gene for LPI.     

Prothrombin kringle-2 domain has a growth inhibitory activity against basic fibroblast growth factor-stimulated capillary endothelial cells

Recently, O'Reilly et al. (O'Reilly, M. S., Holmgren, L., Shing, Y., Chen, C., Rosenthal, R. A., Moses, M., Lane, W. S., Cao, Y., Sage, E. H., and Folkman, J. (1994) Cell 79, 315-328; O'Reilly, M. S., Boehm, T., Shing, Y., Fukai, N., Vasios, G., Lane, W. S., Flynn, E., Birkhead, J. R., Olsen, B. R., and Folkman, J. (1997) Cell 88, 277-285) developed a simple in vitro angiogenesis assay system using bovine capillary endothelial cell proliferation and purified potent angiogenic inhibitors, including angiostatin and endostatin. Using a simple in vitro assay for angiogenesis, we purified a protein molecule that showed anti-endothelial cell proliferative activity from the serum of New Zealand White rabbits, which was stimulated by lipopolysaccharide. The purified protein showed only bovine capillary endothelial cell growth inhibition and not any cytotoxicity. This molecule was identified as a prothrombin kringle-2 domain (fragment-2) using Edman degradation and the amino acid sequence deduced from the cloned cDNA. Both the prothrombin kringle-2 domain released from prothrombin by factor Xa cleavage and the angiogenic inhibitor purified from rabbit sera exhibited anti-endothelial cell proliferative activity. The recombinant rabbit prothrombin kringle-2 domain showed potent inhibitory activity with half-maximal concentrations (ED50) of 2 microg/ml media. As in angiostatin, the recombinant rabbit prothrombin kringle-2 domain also inhibited angiogenesis in the chorioallantoic membrane of chick embryos.     

Structure of cysteine- and glycine-rich protein CRP2. Backbone dynamics reveal motional freedom and independent spatial orientation of the lim domains

Members of the cysteine- and glycine-rich protein family (CRP1, CRP2, and CRP3) contain two zinc-binding LIM domains, LIM1 (amino-terminal) and LIM2 (carboxyl-terminal), and are implicated in diverse cellular processes linked to differentiation, growth control, and pathogenesis. Here we report the solution structure of full-length recombinant quail CRP2 as determined by multi-dimensional triple-resonance NMR spectroscopy. The structural analysis revealed that the global fold of the two LIM domains in the context of the full-length protein is identical to the recently determined solution structures of the isolated individual LIM domains of quail CRP2. There is no preference in relative spatial orientation of the two domains. This supports the view that the two LIM domains are independent structural and presumably functional modules of CRP proteins. This is also reflected by the dynamic properties of CRP2 probed by 15N relaxation values (T1, T2, and nuclear Overhauser effect). A model-free analysis revealed local variations in mobility along the backbone of the two LIM domains in the native protein, similar to those observed for the isolated domains. Interestingly, fast and slow motions observed in the 58-amino acid linker region between the two LIM domains endow extensive motional freedom to CRP2. The dynamic analysis indicates independent backbone mobility of the two LIM domains and rules out correlated LIM domain motion in full-length CRP2. The finding that the LIM domains in a protein encompassing multiple LIM motifs are structurally and dynamically independent from each other supports the notion that these proteins may function as adaptor molecules arranging two or more protein constituents into a macromolecular complex.     

Molecular cloning, expression, and functional significance of a cytochrome P450 highly expressed in rat heart myocytes

A cDNA encoding a P450 monooxygenase was amplified from reverse transcribed rat heart and liver total RNA by polymerase chain reaction using primers based on the 5'- and 3'-end sequences of two rat pseudogenes, CYP2J3P1 and CYP2J3P2. Sequence analysis revealed that this 1,778-base pair cDNA contained an open reading frame and encoded a new 502 amino acid protein designated CYP2J3. Based on the deduced amino acid sequence, CYP2J3 was approximately 70% homologous to both human CYP2J2 and rabbit CYP2J1. Recombinant CYP2J3 protein was co-expressed with NADPH-cytochrome P450 oxidoreductase in Sf9 insect cells using a baculovirus expression system. Microsomal fractions of CYP2J3/NADPH-cytochrome P450 oxidoreductase-transfected cells metabolized arachidonic acid to 14,15-, 11,12-, and 8, 9-epoxyeicosatrienoic acids and 19-hydroxyeicosatetraenoic acid as the principal reaction products (catalytic turnover, 0.2 nmol of product/nmol of cytochrome P450/min at 37 degrees C). Immunoblotting of microsomal fractions prepared from rat tissues using a polyclonal antibody raised against recombinant CYP2J2 that cross-reacted with CYP2J3 but not with other known rat P450s demonstrated abundant expression of CYP2J3 protein in heart and liver. Immunohistochemical staining of formalin-fixed paraffin-embedded rat heart tissue sections using the anti-CYP2J2 IgG and avidin-biotin-peroxidase detection localized expression of CYP2J3 primarily to atrial and ventricular myocytes. In an isolated-perfused rat heart model, 20 min of global ischemia followed by 40 min of reflow resulted in recovery of only 44 +/- 6% of base-line contractile function. The addition of 5 microM 11, 12-epoxyeicosatrienoic acid to the perfusate prior to global ischemia resulted in a significant 1.6-fold improvement in recovery of cardiac contractility (69 +/- 5% of base line, p = 0.01 versus vehicle alone). Importantly, neither 14,15-epoxyeicosatrienoic acid nor 19-hydroxyeicosatetraenoic acid significantly improved functional recovery following global ischemia, demonstrating the specificity of the biological effect for the 11, 12-epoxyeicosatrienoic acid regioisomer. Based on these data, we conclude that (a) CYP2J3 is one of the predominant enzymes responsible for the oxidation of endogenous arachidonic acid pools in rat heart myocytes and (b) 11,12-epoxyeicosatrienoic acid may play an important functional role in the response of the heart to ischemia.