Ornithine-containing lipids stimulate CD14-dependent TNF-alpha production from murine macrophage-like J774.1 and RAW 264.7 cells

The ornithine-containing lipids (OL)-induced cytokine production pattern in macrophage-like J774.1 and RAW 264.7 cells was different from that in the peritoneal macrophages previously reported. OLs, as well as lipopolysaccharide (LPS) of Escherichia coli, strongly induced tumor necrosis factor (TNF) alpha but not interleukin (IL)-1beta in J774.1 cells. In the RAW cells, IL-1beta, TNF-alpha and prostaglandin E(2) were strongly induced by the OLs and LPS. OL- and serine-glycine-containing lipid (SGL)-induced TNF-alpha production in J774.1 and RAW 264.7 cells required serum. However, in CD14-deficient LR-9 cells, TNF-alpha was not induced by the OLs in the presence or absence of serum. OLs and a SGL almost completely inhibited the binding of (125)I-LPS to J774.1 cells. These results suggested that OLs and SGL activate macrophages via the CD14-dependent pathway.     

Cloning of a rat glia maturation factor-gamma (rGMFG) cDNA and expression of its mRNA and protein in rat organs

We isolated a rat glia maturation factor-gamma(rGMFG) cDNA and examined the tissue distribution of GMFG in rat by Northern and Western blot analyses. Sequence analysis of the entire cDNA revealed an open reading frame of 426 nucleotides with a deduced protein of 142 amino acid residues. The deduced amino acid sequence of the putative product is highly homologous (78.9%) to rat glia maturation factor-beta (rGMFB). Northern blot analysis indicated that a 0.9-kb mRNA is predominantly expressed in rat thymus, testis, and spleen. GMFG showed a different tissue distribution from GMFB, being present predominantly in proliferative and differentiative organs.     

A two-hit model for development of multiple endocrine neoplasia type 2B by RET mutations

Multiple endocrine neoplasia (MEN) type 2B mutations have been reported at methionine 918 or alanine 883 in the tyrosine kinase domain of the RET proto-oncogene. Recently, a new combination of two germline missense mutations at valine 804 and tyrosine 806 was identified in a patient with MEN 2B-like clinical phenotypes including medullary thyroid carcinoma, mucosal neuroma, and marfanoid habitus. In this case, valine 804 and tyrosine 806 were replaced with methionine and cysteine, respectively. In the present study, biological activities of RET with these new mutations were compared with those with known MEN 2A or MEN 2B mutations. The transforming activity of RET with the V804M/Y806C mutation was about 8- to 13-fold higher than that of RET with a single V804M or Y806C mutation. Like RET with the M918T or A883F MEN 2B mutation, the transforming activity of RET with the V804M/Y806C mutation was not affected by substitution of phenylalanine for tyrosine 905 that abolished the activity of RET with the MEN 2A mutation. On the other hand, substitution of phenylalanine for tyrosines 864 and 952 drastically diminished the activity of RET with the V804M/Y806C, M918T or A883F mutation, suggesting that these three mutant proteins have similar biological properties.     

Mouse smad8 phosphorylation downstream of BMP receptors ALK-2, ALK-3, and ALK-6 induces its association with Smad4 and transcriptional activity

Smads are intracellular signaling mediators for TGF-beta superfamily. Smad1 and Smad5 are activated by BMP receptors. Here, we have cloned mouse Smad8 and functionally characterized its ability to transduce signals from BMP receptors. Constitutively active BMP type I receptors, ALK-3 and ALK-6, as well as ALK-2, were phosphorylated Smad8 and induced Smad8 interaction with Smad4. Nuclear translocation of Smad8 was stimulated by constitutively active BMP type I receptors. In contrast, constitutively active TGF-beta type I receptor, ALK-5, did not exhibit any action on Smad8. Smad8 and Smad4 cooperatively induced the promoter of Xvent2, a homeobox gene that responds specifically to BMP signaling. Dominant-negative Smad8 was shown to inhibit the increase of alkaline phosphatase activity induced by BMP-2 on pluripotent mesenchymal C3H10T1/2 and myoblastic C2C12 cell lines. The presence of Smad8 mRNA in mouse calvaria cells and osteoblasts suggests a role of Smad8 in the osteoblast differentiation and maturation.     

Silefrin, a sodefrin-like pheromone in the abdominal gland of the sword-tailed newt, Cynops ensicauda

Sodefrin-like female-attracting pheromone was purified from the abdominal glands of male sword-tailed newts, Cynops ensicauda, by gel-filtration chromatography and reversed-phase high-performance liquid chromatography. The final product comprises 10 amino acid residues with the sequence SILSKDAQLK which coincided with the sequence deduced from its precursor cDNA. This peptide was designated silefrin. The sequence of silefrin was different from that of sodefrin by two amino acid residues, with substitutions Leu for Pro and Gln for Leu at positions 3 and 8, respectively. Both native and synthetic silefrin exerted an equipotent activity in attracting conspecific females.     

Cutting edge: endotoxin tolerance in mouse peritoneal macrophages correlates with down-regulation of surface toll-like receptor 4 expression

Monocytes/macrophages exposed to LPS show reduced responses to second stimulation with LPS, which is termed LPS tolerance. In this study, we investigated molecular mechanism of LPS tolerance in macrophages. Mouse peritoneal macrophages pre-exposed to LPS exhibited reduced production of inflammatory cytokines in a time- and dose-dependent manner. Activation of neither IL-1 receptor-associated kinase nor NF-kappaB was observed in macrophages that became tolerant by LPS pretreatment, indicating that the proximal event in Toll-like receptor 4 (TLR4)-MyD88-dependent signaling is affected in tolerant macrophages. Although TLR4 mRNA expression significantly decreased within a few hours of LPS pretreatment and returned to the original level at 24 h, the surface TLR4 expression began to decrease within 1 h, with a gradual decrease after that, and remained suppressed over 24 h. A decrease in inflammatory cytokine production in tolerant macrophages well correlates with down-regulation of the surface TLR4 expression, which may explain one of the mechanisms for LPS tolerance.     

Cancer vaccines: single-epitope anti-idiotype vaccine versus multiple-epitope antigen vaccine

In this study, we compared the immunogenicity and tumor-protective activity of anti-idiotypic antibodies mimicking a single tumor-associated epitope and tumor-associated antigen expressing multiple potentially immunogenic epitopes. We focused our study on the colorectal-carcinoma(CRC)-associated antigen GA733 (also known as CO17-1A/KS1-4/KSA/EpCAM). Monoclonal anti-idiotypic antibody (Ab2) BR3E4 was produced against murine anti-CRC mAb CO17-1A (Ab1) in rats. Full-length native GA733 protein was isolated from human tumor cells, and the extracellular domain protein (GA733-2E) was isolated from supernatants of recombinant baculovirus-infected insect cells by immunoafffinity chromatography. The immunomodulatory activity of the Ab2 was compared with that of the antigen, both in rabbits and in mice. Mice, like humans but not rabbits, express a GA733 antigen homologue on some of their normal tissues. Thus, these in vivo models allow the comparison of the immunogenicity of Ab2 and antigen in the presence (mice) and absence (rabbits) of normal tissue expression and immunological tolerance of the GA733 antigen homologue. In rabbits, aluminum-hydroxide(alum)-precipitated native GA733 antigen was superior to alum-precipitated Ab2 in inducing specific humoral immunity. In mice, alum-precipitated recombinant GA733-2E antigen, but not alum-precipitated Ab2, induced specific humoral immunity. However, when the Ab2 was administered to mice in Freund's complete adjuvant, specific humoral immune responses were elicited. Ab2 in complete Freund's adjuvant and GA733-2E in alum were compared for their capacity to induce antigen-specific cellular immunity in mice. Whereas lymphoproliferative responses were obtained with the recombinant antigen only, delayed-type hypersensitivity responses were obtained with both recombinant antigen and Ab2, although these responses were lower than after antigen immunization. The recombinant antigen in alum did not protect mice against challenge with antigen-positive syngeneic murine CRC cells. Similar studies with Ab2 BR3E4 mimicking the CO17-1A epitope were not possible because the tumor cells do not express this epitope after transfection with the human GA733-2 cDNA. However, similar studies with Ab2 mimicking the epitope defined by mAb GA733, which is expressed by the transfected tumor cells, indicated a lack of tumor-protective activity of this Ab2. In contrast, the full-length antigen expressed by recombinant adenovirus inhibited the growth of established tumors in mice. In conclusion, soluble antigen is a more potent modulator of humoral and cellular immune responses than Ab2, both administered in adjuvant. However, for induction of protective immunity, the immunogenicity of the antigen must be further enhanced, e.g., by expression of the antigen in a viral vector. Received: 27 December 1999 / Accepted: 27 January 2000     

Molecular cloning of mouse thioredoxin reductases

We screened clones for thioredoxin reductase genes with a degenerate PCR-based strategy and have isolated two novel cDNA clones from a mouse thymocyte cDNA library. These encode two distinct thioredoxin reductases (TrxR1 and TrxR2) with 499 and 527 amino acid (aa) residues and calculated molecular masses of 54.5 kDa and 56.8 kDa respectively. These proteins share 90% and 50% aa sequence identity with those of previously cloned human TrxR, containing the redox-active cysteines, FAD binding domain, and the selenocysteine (SeCys) insertion sequence, which is composed of a putative stem-loop sequence located in the 3'-untranslated region (UTR). TrxR2 showing less homology to human TrxR has a mitochondrial translocation signal and a mitochondrial prepeptide protease cleavage site in the N-terminal domain. Transient expression experiments of each gene as fusion proteins with Xpress-tagged protein in NIH 3T3 cells indicated that TrxR1 was localized in the nucleus and cytoplasm and TrxR2 in the mitochondria. Furthermore, we mapped the TrxR1 gene to chromosome 10 (placed 1.71 cR from D10Mit42, lod>3.0) and the TrxR2 gene to chromosome 16 (placed 22.56 cR from D16Mit34, lod>3.0). Thus, the mouse has at least two distinct nuclear genes for TrxR that have different translocation sites in the cell.     

Synthesis of a novel asparagine-linked heptasaccharide structure via p-methoxybenzyl-assisted beta-mannosylation

Synthesis of a core heptasaccharide asparagine N4-[alpha-D-mannopyranosyl-(1 --> 6)-[(alpha-D-mannopyranosyl)-(1 --> 3)]-[(2-acetamido-2-deoxy-beta-D-glucopyranosyl)-(1 --> 2)]-(beta-D-mannopyranosyl)-(1 --> 4)-(2-acetamido-2-deoxy-beta-D-glucopyranosyl)-(1 --> 4)-[(alpha-L-fucopyranosyl)-(1 --> 6)]-2-acetamido-2-deoxy-beta-D-glucopyranosyl]-L-asparagine (1a) found from CHO glycosylation mutant cell LEC 14 is described. The structure of 1a is highly novel in terms of the presence of an extra GlcNAc residue linked to the 2-position of beta-linked mannose. The synthesis was performed using p-methoxybenzyl-assisted intramolecular aglycon delivery as the key transformation. 4,6-O-TIDPS-protected thiomannoside methyl 2-O-p-methoxybenzyl-4,6-O-(1,1,3,3-tetraisopropyl)disiloxanylid ene-3-O-trimethylsilyl-1-thio-alpha-D-mannopyranoside was adopted for this particular purpose, which afforded beta-mannoside p-methoxyphenyl 2,3-O-(p-methoxybenzylidene)-4,6-O-(1,1,3,3-tetraisopropyl)+ ++disiloxanylidene-beta-D-mannopyranosyl-(1 --> 4)-3,6-di-O-benzyl-2-deoxy-2-phthalimido-beta-D-glucopyranoside stereoselectively in 75% yield.     

Lignans causing photodiscoloration of Tsuga heterophylla: 8-hydroxy-oxomatairesinol from sapwood

A lignan, (8S,8'S,)-(+)-8-hydroxy-oxomatairesinol, has been isolated from the sapwood of Tsuga heterophylla (western hemlock, Pinaceae). The known lignans matairesinol, lariciresinol and secoisolariciresinol were also obtained. The structure of the compound was established by 1D and 2D NMR spectroscopy. Results of the light-irradiation test of the lignans from T. heterophylla are also reported.