Redox-coupled crystal structural changes in bovine heart cytochrome c oxidase

Crystal structures of bovine heart cytochrome c oxidase in the fully oxidized, fully reduced, azide-bound, and carbon monoxide-bound states were determined at 2.30, 2.35, 2.9, and 2.8 angstrom resolution, respectively. An aspartate residue apart from the O2 reduction site exchanges its effective accessibility to the matrix aqueous phase for one to the cytosolic phase concomitantly with a significant decrease in the pK of its carboxyl group, on reduction of the metal sites. The movement indicates the aspartate as the proton pumping site. A tyrosine acidified by a covalently linked imidazole nitrogen is a possible proton donor for the O2 reduction by the enzyme.

Follicular growth and atresia in mammalian ovaries: regulation by survival and death of granulosa cells

The mammalian ovary is an extremely dynamic organ in which a large majority of follicles are effectively eliminated throughout their reproductive life. Due to the numerous efforts of researchers, mechanisms regulating follicular growth and atresia in mammalian ovaries have been clarified, not only their systemic regulation by hormones (gonadotropins) but also their intraovarian regulation by gonadal steroids, growth factors, cytokines and intracellular proteins. Granulosa cells in particular have been demonstrated to play a major role in deciding the fate of follicles, serving molecules that are essential for follicular growth and maintenance as well as killing themselves by an apoptotic process that results in follicular atresia. In this review, we discuss the factors that govern follicular growth and atresia, with a special focus on their regulation by granulosa cells. First, ovarian folliculogenesis in adult life is outlined. Then, we explain about the regulation of follicular growth and atresia by granulosa cells, in which hormones, growth factors and cytokines, death ligand-receptor system and B cell lymphoma/leukemia 2 (BCL2) family members (mitochondria-mediated apoptosis) are further discussed.

The cloning of PIG-A, a component in the early step of GPI-anchor biosynthesis

The glycosylphosphatidylinositol (GPI) anchor is a membrane attachment structure of many proteins and occurs in a wide variety of eukaryotes from yeasts to mammals. The structure of the core of the GPI anchor is conserved in protozoa and mammals and so is its biosynthetic pathway. A complementary DNA encoding a human protein termed PIG-A (phosphatidylinositol glycan-class A) was cloned. PIG-A was necessary for synthesis of N-acetylglucosaminyl-phosphatidylinositol, the very early intermediate in GPI-anchor biosynthesis.

Smad2 and Smad3 are redundantly essential for the TGF-beta-mediated regulation of regulatory T plasticity and Th1 development

Although it has been well established that TGF-beta plays a pivotal role in immune regulation, the roles of its downstream transcription factors, Smad2 and Smad3, have not been fully clarified. Specifically, the function of Smad2 in the immune system has not been investigated because of the embryonic lethality of Smad2-deficient mice. In this study, we generated T cell-specific Smad2 conditional knockout (KO) mice and unexpectedly found that Smad2 and Smad3 were redundantly essential for TGF-beta-mediated induction of Foxp3-expressing regulatory T cells and suppression of IFN-gamma production in CD4(+) T cells. Consistent with these observations, Smad2/Smad3-double KO mice, but not single KO mice, developed fatal inflammatory diseases with higher IFN-gamma production and reduced Foxp3 expression in CD4(+) T cells at the periphery. Although it has been suggested that Foxp3 induction might underlie TGF-beta-mediated immunosuppression, TGF-beta still can suppress Th1 cell development in Foxp3-deficient T cells, suggesting that the Smad2/3 pathway inhibits Th1 cell development with Foxp3-independent mechanisms. We also found that Th17 cell development was reduced in Smad-deficient CD4(+) T cells because of higher production of Th17-inhibitory cytokines from these T cells. However, TGF-beta-mediated induction of RORgamma t, a master regulator of Th17 cell, was independent of both Smad2 and Smad3, suggesting that TGF-beta regulates Th17 development through Smad2/3-dependent and -independent mechanisms.

Human herpesvirus 6B genome sequence: coding content and comparison with human herpesvirus 6A

Human herpesvirus 6 variants A and B (HHV-6A and HHV-6B) are closely related viruses that can be readily distinguished by comparison of restriction endonuclease profiles and nucleotide sequences. The viruses are similar with respect to genomic and genetic organization, and their genomes cross-hybridize extensively, but they differ in biological and epidemiologic features. Differences include infectivity of T-cell lines, patterns of reactivity with monoclonal antibodies, and disease associations. Here we report the complete genome sequence of HHV-6B strain Z29 [HHV-6B(Z29)], describe its genetic content, and present an analysis of the relationships between HHV-6A and HHV-6B. As sequenced, the HHV-6B(Z29) genome is 162,114 bp long and is composed of a 144,528-bp unique segment (U) bracketed by 8,793-bp direct repeats (DR). The genomic sequence allows prediction of a total of 119 unique open reading frames (ORFs), 9 of which are present only in HHV-6B. Splicing is predicted in 11 genes, resulting in the 119 ORFs composing 97 unique genes. The overall nucleotide sequence identity between HHV-6A and HHV-6B is 90%. The most divergent regions are DR and the right end of U, spanning ORFs U86 to U100. These regions have 85 and 72% nucleotide sequence identity, respectively. The amino acid sequences of 13 of the 17 ORFs at the right end of U differ by more than 10%, with the notable exception of U94, the adeno-associated virus type 2 rep homolog, which differs by only 2.4%. This region also includes putative cis-acting sequences that are likely to be involved in transcriptional regulation of the major immediate-early locus. The catalog of variant-specific genetic differences resulting from our comparison of the genome sequences adds support to previous data indicating that HHV-6A and HHV-6B are distinct herpesvirus species.

Molecular cloning and functional characterization of the receptor for Clostridium perfringens enterotoxin

A cDNA encoding the Clostridium perfringens enterotoxin receptor gene (CPE-R) was cloned from an expression library of enterotoxin-sensitive Vero cells. The nucleotide sequence of CPE-R showed that the enterotoxin receptor consists of 209 amino acids with a calculated molecular mass of 22,029 D. This receptor is highly hydrophobic, contains four putative transmembrane segments, and has significant similarity to the rat androgen withdrawal apoptosis protein RVP1 and the mouse oligodendrocyte specific protein, the functions of which are unknown. The expression of CPE-R was detected in the enterotoxin-sensitive Vero, Hep3B, and Intestine 407 cell lines, but not in the enterotoxin-insensitive K562 and JY cell lines. The CPE-R gene product expressed in enterotoxin-resistant L929 cells bound to enterotoxin specifically and directly and with high affinity and rendered the cells sensitive to the toxin, indicating that the cloned receptor is functional. Results showed that enterotoxin could not assemble into a complex with a defined structure unless it interacted with the receptor. From these results, it is proposed that the enterotoxin receptor is required for both target cell recognition and pore formation in the cell membrane.

Hypotension and reduced nitric oxide-elicited vasorelaxation in transgenic mice overexpressing endothelial nitric oxide synthase

Nitric oxide (NO), constitutively produced by endothelial nitric oxide synthase (eNOS), plays a major role in the regulation of blood pressure and vascular tone. We generated transgenic mice overexpressing bovine eNOS in the vascular wall using murine preproendothelin-1 promoter. In transgenic lineages with three to eight transgene copies, bovine eNOS-specific mRNA, protein expression in the particulate fractions, and calcium-dependent NOS activity were confirmed by RNase protection assay, immunoblotting, and L-arginine/citrulline conversion. Immunohistochemical studies revealed that eNOS protein was predominantly localized in the endothelial cells of aorta, heart, and lung. Blood pressure was significantly lower in eNOS-overexpressing mice than in control littermates. In the transgenic aorta, basal NO release (estimated by Nomega-nitro-L-arginine-induced facilitation of the contraction by prostaglandin F2alpha) and basal cGMP levels (measured by enzyme immunoassay) were significantly increased. In contrast, relaxations of transgenic aorta in response to acetylcholine and sodium nitroprusside were significantly attenuated, and the reduced vascular reactivity was associated with reduced response of cGMP elevation to these agents as compared with control aortas. Thus, our novel mouse model of chronic eNOS overexpression demonstrates that, in addition to the essential role of eNOS in blood pressure regulation, tonic NO release by eNOS in the endothelium induces the reduced vascular reactivity to NO-mediated vasodilators, providing several insights into the pathogenesis of nitrate tolerance.

Shear stress modulates expression of Cu/Zn superoxide dismutase in human aortic endothelial cells

A major determinant of the level of cellular superoxide anion (O2-.) is the dismutation of O2-. to hydrogen peroxide by the enzyme superoxide dismutase (SOD). Three forms of SOD exist, but in endothelial cells, the major form outside of the mitochondria is the cytosolic copper/zinc-containing superoxide dismutase (Cu/Zn SOD). Since fluid shear stress is an important determinant of the function and structure of endothelial cells in vivo, we examined the effect of laminar shear stress on the expression of Cu/Zn SOD in cultured human aortic endothelial cells. Laminar shear stress of 0.6 to 15 dyne/cm2 increased Cu/Zn SOD mRNA in a time- and dose-dependent manner in human aortic endothelial cells. Shear stress also increased both Cu/Zn SOD protein content and the enzyme activity. Nuclear runon assays showed that nuclei from human aortic endothelial cells exposed to laminar shear stress had a 1.6-fold greater transcriptional activity of the Cu/Zn SOD gene compared with cells not exposed to shear, indicating that an increase in Cu/Zn SOD mRNA induced by laminar shear stress is at least in part mediated by increased transcription. In contrast, shear stress had no effect on Cu/Zn SOD mRNA levels in human aortic smooth muscle cells. These findings show that physiological levels of shear stress increase expression of Cu/Zn SOD in the endothelium. This adaptation to shear stress might augment the effect of locally produced NO. and thereby promote the antiatherogenic and anti-inflammatory properties of the endothelial cell.

Anti-oxidative properties of fluvastatin, an HMG-CoA reductase inhibitor, contribute to prevention of atherosclerosis in cholesterol-fed rabbits

Studies in vitro reveal that fluvastatin, an HMG-CoA reductase inhibitor, has a strong DPPH radical scavenging activity and achieves concentration-dependent inhibition of copper- and cell-induced oxidation of low-density lipoprotein (LDL). To further examine the anti-oxidative activity of fluvastatin in vivo, we elucidated the effects of chronic treatment with fluvastatin at a dose insufficient to reduce plasma cholesterol levels (2 mg/kg per day) on vasomotion and vascular oxidative stress in thoracic aortas of 0.5% cholesterol-fed rabbits. After 12 weeks of dietary treatment, aortic segments from rabbits fed cholesterol alone showed impaired endothelium-dependent relaxation responses to acetylcholine and A23187 compared to normal chow-fed rabbits in association with a significant increase in plasma total cholesterol levels. In contrast, although plasma total cholesterol levels were not different from those in control cholesterol-fed rabbits, aortic segments from fluvastatin-treated rabbits showed normal relaxation. Compared with rabbits fed cholesterol alone, fluvastatin treatment decreased susceptibility of LDL to ex vivo copper-induced oxidation, reduced vascular superoxide generation, and atheromatous plaque formation. In conclusion, the potent anti-oxidative properties of fluvastatin in addition to its cholesterol-lowering activity appear to contribute to its anti-atherosclerotic effect in vivo.

Clostridium perfringens enterotoxin utilizes two structurally related membrane proteins as functional receptors in vivo

Human and mouse cDNAs showing homology to the Clostridium perfringens enterotoxin (CPE) receptor gene (CPE-R) from Vero cells (DDBJ/EMBL/GenBankTM accession no. D88492) (Katahira, J., Inoue, N., Horiguchi, Y., Matsuda, M., and Sugimoto, N. (1997) J. Cell Biol. 136, 1239-1247) were cloned. They were classified into two groups, the Vero cell CPE receptor homologues and rat androgen withdrawal apoptosis protein (RVP1; accession no. M74067) homologues, based on the similarities of primary amino acid sequences. L929 cells that were originally insensitive to CPE became sensitive to CPE on their transfection with cDNAs encoding either the CPE receptor or RVP1 homologues, indicating that these gene products are not only structurally similar but also functionally active as receptors for CPE. By binding assay, the human RVP1 homologue showed differences in affinity and capacity of binding from those of the human CPE receptor. Northern blot analysis showed that mouse homologues of the CPE receptor and RVP1 are expressed abundantly in mouse small intestine. The expression of CPE-R mRNA in the small intestine was restricted to cryptic enterocytes, indicating that the CPE receptor is expressed in intestinal epithelial cells. These results are consistent with reports that CPE binds to the small intestinal cells via two different kinds of receptors. High levels of expression of CPE-R and/or RVP1 mRNA were also detected in other organs, including the lungs, liver, and kidneys, but only low levels were expressed in heart and skeletal muscles. These results indicate that CPE uses structurally related cellular proteins as functional receptors in vivo and that organs that have not so far been recognized as CPE-sensitive have the potential to be targets of CPE.

Polymorphism of the NADH/NADPH oxidase p22 phox gene in patients with coronary artery disease

BACKGROUND

Oxidative stress in the vasculature has been implicated in the pathogenesis of coronary artery disease (CAD). NADH/NADPH oxidase is a key enzyme of superoxide production in the vasculature. p22 phox, an essential component of NADH/NADPH oxidase, has four types of polymorphism. The C242T polymorphism changes histidine-72 to tyrosine, located in the potential heme-binding sites, whereas A640G polymorphism is located in the 3' untranslated region.

METHODS AND RESULTS

We investigated whether these polymorphisms were associated with risk of CAD by use of restriction fragment length polymorphism (RFLP). The prevalence of the TC + TT genotype of the C242T polymorphism was significantly more frequent in control subjects (n=201) than in the patients with CAD (n=201). The odds ratio of the TC + TT versus CC genotype of the C242T polymorphism between control subjects and case patients was 0.49 (95% CI, 0.28 to 0.87) (P=.015). The prevalence of the genotypes of the A640G polymorphism was not different between groups. The association of C242T polymorphism of the p22 phox gene with CAD was statistically significant and independent of other risk factors.

CONCLUSIONS

The mutation of the potential heme-binding site of the p22 phox gene may reduce susceptibility to CAD. Our observations suggest that the C242T polymorphism of the p22 phox gene is a novel genetic marker that has a protective effect on coronary risk.

Relationship between sugar chain structure and biological activity of recombinant human erythropoietin produced in Chinese hamster ovary cells

Two forms of erythropoietin, EPO-bi and EPO-tetra, with different biological activities were isolated from the culture medium of a recombinant Chinese hamster ovary cell line, B8-300, into which the human erythropoietin gene had been introduced. EPO-bi, an unusual form, showed only one-seventh the in vivo activity and 3 times higher in vitro activity of the previously described recombinant human EPO (standard EPO). In contrast, EPO-tetra showed both in vivo and in vitro activities comparable to those of the standard EPO. EPO-bi, EPO-tetra, and the standard EPO had the same amino acid composition and immunoreactivity. However, structural analyses of their N-linked sugar chains revealed that EPO-bi contains the biantennary complex type as the major sugar chain, while EPO-tetra and the standard EPO contain the tetraantennary complex type as the major sugar chain. From examination of various preparations of recombinant human EPO, we found a positive correlation between the in vivo activity of EPO and the ratio of tetraantennary to biantennary oligosaccharides. These results suggest that higher branching of the N-linked sugar chains is essential for effective expression of in vivo biological activity of EPO.

Expression of NADH/NADPH oxidase p22phox in human coronary arteries

BACKGROUND

NADH/NADPH oxidase is an important source of superoxide in the vasculature. Recently, we found that polymorphism of the gene p22phox, a critical component of this oxidase, is associated with a risk of coronary artery disease. The aim of this study was to investigate the localization of p22phox in human coronary arteries and to examine its difference in expression between nonatherosclerotic and atherosclerotic coronary arteries.

METHODS AND RESULTS

Using coronary artery sections from autopsied cases (n=11), the expression of p22phox was examined by immunohistochemistry and Western blotting. In nonatherosclerotic coronary arteries, p22phox was weakly expressed, mainly in the adventitia. In atherosclerotic coronary arteries, intensive immunoreactivity was detected in neointimal and medial smooth muscle cells and infiltrating macrophages in hypercellular regions and at the shoulder region. Semiquantitative analysis and Western blotting showed that the expression of p22phox in atherosclerotic coronary arteries was more pronounced than that in nonatherosclerotic arteries. Double staining revealed p22phox expression in adventitial fibroblasts, smooth muscle cells, macrophages in the neointima and media, and endothelial cells.

CONCLUSIONS

As atherosclerosis progressed, the expression of p22phox increased through the vessel wall. p22phox might participate in the pathogenesis and pathophysiology of atherosclerotic coronary disease.

Sterol regulatory element-binding proteins induce an entire pathway of cholesterol synthesis

To evaluate the effects of sterol regulatory element-binding proteins (SREBPs) on the expression of the individual enzymes in the cholesterol synthetic pathway, we examined expression of these genes in the livers from wild-type and transgenic mice overexpressing nuclear SREBP-1a or -2. As estimated by a Northern blot analysis, overexpression of nuclear SREBP-1a or -2 caused marked increases in mRNA levels of the whole battery of cholesterogenic genes. This SREBP activation covers not only rate-limiting enzymes such as HMG CoA synthase and reductase that have been well established as SREBP targets, but also all the enzyme genes in the cholesterol synthetic pathway tested here. The activated genes include mevalonate kinase, mevalonate pyrophosphate decarboxylase, isopentenyl phosphate isomerase, geranylgeranyl pyrophosphate synthase, farnesyl pyrophosphate synthase, squalene synthase, squalene epoxidase, lanosterol synthase, lanosterol demethylase, and 7-dehydro-cholesterol reductase. These results demonstrate that SREBPs activate every step of cholesterol synthetic pathway, contributing to an efficient cholesterol synthesis.

Regulation mechanism of selective atresia in porcine follicles: regulation of granulosa cell apoptosis during atresia

More than 99% of follicles undergo a degenerative process known as "atresia", in mammalian ovaries, and only a few follicles ovulate during ovarian follicular development. We have investigated the molecular mechanism of selective follicular atresia in mammalian ovaries, and have reported that follicular selection dominantly depends on granulosa cell apoptosis. However, we have little knowledge of the molecular mechanisms that control apoptotic cell death in granulosa cells during follicle selection. To date, at least five cell death ligand-receptor systems [tumor necrosis factor (TNF)alpha and receptors, Fas (also called APO-1/CD95) ligand and receptors, TNF-related apoptosis-inducing ligand (TRAIL; also called APO-2) and receptors, APO-3 ligand and receptors, and PFG-5 ligand and receptors] have been reported in granulosa cells of porcine ovaries. Some cell death ligand-receptor systems have "decoy" receptors, which act as inhibitors of cell death ligand-induced apoptosis in granulosa cells. Moreover, we showed that the porcine granulosa cell is a type II apoptotic cell, which has the mitochondrion-dependent apoptosis-signaling pathway. Briefly, the cell death receptor-mediated apoptosis signaling pathway in granulosa cells has been suggested to be as follows. (1) A cell death ligand binds to the extracellular domain of a cell death receptor, which contains an intracellular death domain (DD). (2) The intracellular DD of the cell death receptor interacts with the DD of the adaptor protein (Fas-associated death domain: FADD) through a homophilic DD interaction. (3) FADD activates an initiator caspase (procaspase-8; also called FLICE), which is a bipartite molecule, containing an N-terminal death effector domain (DED) and a C-terminal DD. (4) Procaspase-8 begins auto-proteolytic cleavage and activation. (5) The auto-activated caspase-8 cleaves Bid protein. (6) The truncated Bid releases cytochrome c from mitochondrion. (7) Cytochrome c and ATP-dependent oligimerization of apoptotic protease-activating factor-1 (Apaf-1) allows recruitment of procaspase-9 into the apoptosome complex. Activation of procaspase-9 is mediated by means of a conformational change. (8) The activated caspase-9 cleaves downstream effector caspases (caspase-3). (9) Finally, apoptosis is induced. Recently, we found two intracellular inhibitor proteins [cellular FLICE-like inhibitory protein short form (cFLIPS) and long form (cFLIPL)], which were strongly expressed in granulosa cells, and they may act as anti-apoptotic/survival factors. Further in vivo and in vitro studies will elucidate the largely unknown molecular mechanisms, e. g. which cell death ligand-receptor system is the dominant factor controlling the granulosa cell apoptosis of selective follicular atresia in mammalian ovaries. If we could elucidate the molecular mechanism of granulosa cell apoptosis (follicular selection), we could accurately diagnose the healthy ovulating follicles and precisely evaluate the oocyte quality. We hope that the mechanism will be clarified and lead to an integrated understanding of the regulation mechanism.

Involvement of NADH/NADPH oxidase in human platelet ROS production

Platelets play an important role in atherosclerotic and thromboembolic vascular diseases. It has been reported that reactive oxygen species (ROS) could modify platelet function, and platelets themselves have the ability to produce ROS. However, the enzymatic sources of ROS in platelets have not been fully determined. The NADH/NADPH oxidase system was originally identified as the major source of ROS in phagocytes. Recently, it has become evident that this oxidase is functionally expressed not only in phagocytes but also in various cell types. The present study was undertaken to test the hypothesis that NADH/NADPH oxidase might be expressed in human platelets. Lucigenin-enhanced chemiluminescence (L-CL) and electron spin resonance (ESR) method demonstrated that human platelets obtained from healthy volunteers released ROS, and the released ROS were increased by stimulation with 12-O-tetradecanoylphorbol-13-acetate (TPA) or calcium ionophore. Homogenates of human platelets, as well as MEG01 cells, megakaryocytic cell line, had the enzymatic activity to produce superoxide in NADH/NADPH-dependent manners. This enzymatic activity was suppressed by diphenylene iodonium (DPI), an inhibitor of NADH/NADPH oxidase. Western blot analysis demonstrated that platelets and MEG01 cells expressed p22(phox) and p67(phox) proteins, components of NADH/NADPH oxidase. Thus, human platelets have the enzymatic activity of p22(phox)-based NADH/NADPH oxidase, and this oxidase is likely one of the important sources of ROS in platelets.

Dissecting and manipulating the pathway for glycosylphos-phatidylinositol-anchor biosynthesis

The pathway for glycosylphosphatidylinositol-anchor biosynthesis consists of at least 10 reaction steps. Many of the genes encoding the enzymes and regulators involved in this pathway have been recently cloned and their products characterised. These studies have revealed the common and also different characteristics of glycosylphosphatidyl-inositol biosynthesis enzymes in different organisms, leading to the development of species-specific inhibitors of the pathway.

Molecular regulation of the bovine endothelial cell nitric oxide synthase by transforming growth factor-beta 1

The promoter region of the endothelial cell nitric oxide synthase (ecNOS) gene contains potential response elements for transforming growth factor-beta 1 (TGF beta 1). TGF beta 1 plays an important role in the pathogenesis of atherosclerosis, vascular hypertrophy, and angiogenesis. We therefore sought to determine whether TGF beta 1 might modulate ecNOS expression in bovine aortic endothelial cells (BAEC). TGF beta 1 increased ecNOS mRNA in a dose-dependent manner. TGF beta 1 also increased ecNOS protein content. The production of nitrogen oxides (NOx), assessed by chemiluminescence, and nitric oxide synthase activity, assessed by arginine/citrulline conversion were increased in TGF beta 1-treated cells. Transcriptional activity of the 5'-flanking promoter region of the ecNOS gene was increased by TGF beta 1, as assessed by transfection with promoter/luciferase constructs. Deletion analysis suggested that the TGF beta 1-response element was present between nucleotides -1269 and -935 from the first transcription start site, in which a putative nuclear factor-1 (NF-1) binding site existed. Gel shift assays showed that nuclear protein(s), immunologically similar to CCAAT transcription factor/NF-1, bound to the putative NF-1 binding site in a sequence-specific manner. Mutation of the putative NF-1 binding site in the promoter/luciferase construct significantly decreased the responsiveness to TGF beta 1. In conclusion, TGF beta 1 increases ecNOS expression associated with an increase in production of NO in BAEC. This response is probably mediated by transcriptional activation of the ecNOS gene promoter.

New bone formation in an osteoblastic tumor model is increased by endothelin-1 overexpression and decreased by endothelin A receptor blockade

OBJECTIVES

The osteoblastic response of bone to metastatic prostate cancer is both characteristic and enigmatic. The potent vasoconstrictor endothelin-1 (ET-1), produced by prostate cancer, has been identified as a potential factor in new bone formation.

METHODS

Using a novel method to quantitate new bone formation induced by the WISH tumor, we examined the effects of ET-1 overexpression and endothelin receptor antagonists on the osteoblastic response.

RESULTS

WISH, a human tumor cell line derived from amnion, produces ET-1 mRNA and protein and induces abundant new bone formation and splenomegaly in vivo. Stable transfection of WISH with an ET-1 overexpression cDNA construct produced clones that secreted 18-fold more bioactive ET-1 than vector-only controls. After 14 days of growth in the lower leg of nu/nu mice, ET-1 overexpressing tumors produced significantly more new bone than vector-only controls. Conversely, areas of new bone formation were significantly less in animals treated with a selective endothelin A (ET(A)) receptor antagonist A127722.

CONCLUSIONS

The activity of ET-1 in this osteoblastic model provides a unique target for therapy.

Actomyosin tension is required for correct recruitment of adherens junction components and zonula occludens formation

The adherens junction (AJ) densely associated with actin filaments is a major cell-cell adhesion structure. To understand the importance of actin filament association in AJ formation, we first analyzed punctate AJs in NRK fibroblasts where one actin cable binds to one AJ structure unit. The accumulation of AJ components such as the cadherin/catenin complex and vinculin, as well as the formation of AJ-associated actin cables depended on Rho activity. Inhibitors for the Rho target, ROCK, which regulates myosin II activity, and for myosin II ATPase prevented the accumulation of AJ components, indicating that myosin II activity is more directly involved than Rho activity. Depletion of myosin II by RNAi showed similar results. The inhibition of myosin II activity in polarized epithelial MTD-1A cells affected the accumulation of vinculin to circumferential AJ (zonula adherens). Furthermore, correct zonula occludens (tight junction) formation along the apicobasal axis that requires cadherin activity was also impaired. Although MDCK cells which are often used as typical epithelial cells do not have a typical zonula adherens, punctate AJs formed dependently on myosin II activity by inducing wound closure in a MDCK cell sheet. These findings suggest that tension generated by actomyosin is essential for correct AJ assembly.

Molecular cloning and functional characterization of chicken toll-like receptors. A single chicken toll covers multiple molecular patterns

Toll-like receptors (TLR) in the innate immune system have not been identified in non-mammalian vertebrates. Two types of TLR were cloned from a chicken bursa cDNA library using degenerate primers based on the consensus sequences of mouse and Drosophila Toll and designated as chicken TLR (chTLR) type 1 and type 2. Of the nine human TLRs reported to date, these chTLRs showed the highest homology to human TLR2. The extracellular regions of type 1 and type 2 contained a distinct approximately 200-amino acid stretch and were 45.3 and 46.3% homologous to that of human TLR2. The intracellular Toll/interleukin-1R homology domain of type 1 and type 2 was perfectly identical to each other and highly homologous (80.7%) to that of human TLR2. Both types were widely detected by reverse transcriptase-polymerase chain reaction and immunoblotting in various chicken organs, especially those rich in connective tissue. Both genes were mapped to chromosome 4q1.1, suggesting that they arose by gene duplication. By reporter gene assay, type 2 and to a lesser extent type 1, selectively signaled the presence of mycoplasma macrophage-activating lipopeptide-2/M161Ag in the human embryonic kidney 293 cell system. Cotransfection of type 2 and human CD14 or MD-2 into human embryonic kidney 293 cells allowed the response to Escherichia coli lipopolysaccharide (LPS), whereas type 1 did not signal LPS or any other microbial components tested. These results indicated that chTLR type 2 covers two major microbe patterns, lipoproteins and LPS, which are regulated by TLR2 and TLR4 in mammals. In oviparous animals, the duplicated TLRs in the pattern-recognition system may function for host-pathogen discrimination in a manner that is distinct from that in mammals.

Induction of the p16INK4a senescence gene as a new therapeutic strategy for the treatment of rheumatoid arthritis

Synovial tissue affected by rheumatoid arthritis is characterized by proliferation, which leads to irreversible cartilage and bone destruction. Current and experimental treatments have been aimed mainly at correcting the underlying immune abnormalities, but these treatments often prove ineffective in preventing the invasive destruction. We studied the expression of cyclin-dependent kinase inhibitors in rheumatoid synovial cells as a means of suppressing synovial cell proliferation. Synovial cells derived from hypertrophic synovial tissue readily expressed p16INK4a when they were growth-inhibited. This was not seen in other fibroblasts, including those derived from normal and osteoarthritis-affected synovial tissues. In vivo adenoviral gene therapy with the p16INK4a gene efficiently inhibited the pathology in an animal model of rheumatoid arthritis. Thus, the induction of p16INK4a may provide a new approach to the effective treatment of rheumatoid arthritis.

Selective cerebral perfusion during operation for aneurysms of the aortic arch: a reassessment

Thirty-two consecutive patients with thoracic aortic aneurysms who required aortic arch reconstruction were operated on with the aid of extracorporeal circulation and selective cerebral perfusion between January 1986 and August 1990. For selective cerebral perfusion, blood was infused into both the innominate and left common carotid arteries at a rate of 10 mL.kg-1.min-1 using a single roller pump separately from the systemic circulation. In 9 patients treated before March 1987, the operations were performed without open aortic anastomosis (group 1), whereas in 23 patients treated from March 1987 onward we used open aortic anastomosis (group 2). The extracorporeal circulation and cardiac arrest times were significantly longer in group 2, but there was no significant difference in the cerebral perfusion time. Early death occurred in 1 patient in group 1 and 2 in group 2. No serious cerebrospinal neurological complications occurred in either group, and there were similar rates of postoperative hepatic and renal dysfunction in both groups. The present data suggest that selective cerebral perfusion and open aortic anastomosis are useful methods for thoracic aortic aneurysm operation requiring complex repair of the aortic arch.

The distribution of calcineurin in rat brain by light and electron microscopic immunohistochemistry and enzyme-immunoassay

Calcineurin is the calcium (divalent cations)-dependent calmodulin-stimulated phosphoprotein phosphatase which is capable of dephosphorylating various substrate proteins. The subcellular and regional distribution of calcineurin in the rat brain has been studied by light and electron microscopic immunohistochemistry using antiserum against calcineurin. Immunoreactivity was observed in many neurons but was not detected in glial cells, such as astrocytes, oligodendrocytes and ependymal cells by the PAP method. Light microscopy demonstrates strong immunoreactivity in neuronal somata and neurites. By electron microscopy, calcineurin immunoreactivity was found to be present in dendrites including postsynaptic densities, somata, spines, axons and terminals. Calcineurin immunoreactivity was present in neurons throughout the brain, but a marked regional variation in strength of the immunoreactivity was observed. The caudatoputamen, hippocampal formation, and substantia nigra were strongly stained. Cerebral and cerebellar neocortex showed moderate immunoreactivity. In substantia nigra and globus pallidus, only neurites were stained, but neuronal somata not. The staining of the substantia nigra was thought to be due to that of the nerve terminals originating from the caudatoputamen, in view of the findings by cerebral hemitransection and electron microscopic immunohistochemistry. We developed an enzyme-immunoassay (EIA) for calcineurin. The sensitivity of the EIA was 1 ng (13 fmol) of calcineurin. We determined the level of calcineurin in various regions of the rat brain. The caudate nucleus, putamen and hippocampal formation showed a high concentration of calcineurin. The results are consistent with those obtained by immunohistochemistry.

Regression of coronary atherosclerosis by combined LDL-apheresis and lipid-lowering drug therapy in patients with familial hypercholesterolemia: a multicenter study. The LARS Investigators

The purpose of the LDL-Apheresis Regression Study (LARS) group, which included 13 institutions in Japan, was to investigate the effects on coronary atherosclerosis of LDL-apheresis combined with cholesterol-lowering drugs. Changes in coronary artery stenosis were assessed angiographically in 37 patients with familial hypercholesterolemia (7 homozygotes and 25 heterozygotes) and hypercholesterolemia which had not been defined as familial hypercholesterolemia (5 patients) by visual judgement and computer analysis. Definite regression was observed in 14 cases, including 4 homozygotes and 10 heterozygotes and others. Regression occurred as often in patients with severe coronary artery disease (2 or more vessel disease) as in those having less severe disease. Our results encourage initiation of aggressive cholesterol-lowering therapy to produce regression of coronary atherosclerosis in FH patients at high risk for cardiovascular events.