Showing papers by "Kyoto University published in 1998"

Claudin-1 and -2: Novel Integral Membrane Proteins Localizing at Tight Junctions with No Sequence Similarity to Occludin

Abstract: Occludin is the only known integral membrane protein localizing at tight junctions (TJ), but recent targeted disruption analysis of the occludin gene indicated the existence of as yet unidentified integral membrane proteins in TJ. We therefore re-examined the isolated junction fraction from chicken liver, from which occludin was first identified. Among numerous components of this fraction, only a broad silver-stained band ∼22 kD was detected with the occludin band through 4 M guanidine-HCl extraction as well as sonication followed by stepwise sucrose density gradient centrifugation. Two distinct peptide sequences were obtained from the lower and upper halves of the broad band, and similarity searches of databases allowed us to isolate two full-length cDNAs encoding related mouse 22-kD proteins consisting of 211 and 230 amino acids, respectively. Hydrophilicity analysis suggested that both bore four transmembrane domains, although they did not show any sequence similarity to occludin. Immunofluorescence and immunoelectron microscopy revealed that both proteins tagged with FLAG or GFP were targeted to and incorporated into the TJ strand itself. We designated them as “claudin-1” and “claudin-2”, respectively. Although the precise structure/function relationship of the claudins to TJ still remains elusive, these findings indicated that multiple integral membrane proteins with four putative transmembrane domains, occludin and claudins, constitute TJ strands.

Birational Geometry of Algebraic Varieties

Abstract: 1. Rational curves and the canonical class 2. Introduction to minimal model program 3. Cone theorems 4. Surface singularities 5. Singularities of the minimal model program 6. Three dimensional flops 7. Semi-stable minimal models.

The chemokine receptor CXCR4 is essential for vascularization of the gastrointestinal tract.

Abstract: Vascularization of organs generally occurs by remodelling of the preexisting vascular system during their differentiation and growth to enable them to perform their specific functions during development. The molecules required by early vascular systems, many of which are receptor tyrosine kinases and their ligands, have been defined by analysis of mutant mice. As most of these mice die during early gestation before many of their organs have developed, the molecules responsible for vascularization during organogenesis have not been identified. The cell-surface receptor CXCR4 is a seven-transmembrane-spanning, G-protein-coupled receptor for the CXC chemokine PBSF/SDF-1 (for pre-B-cell growth-stimulating factor/stromal-cell-derived factor), which is responsible for B-cell lymphopoiesis, bone-marrow myelopoiesis and cardiac ventricular septum formation. CXCR4 also functions as a co-receptor for T-cell-line tropic human immunodeficiency virus HIV-1. Here we report that CXCR4 is expressed in developing vascular endothelial cells, and that mice lacking CXCR4 or PBSF/SDF-1 have defective formation of the large vessels supplying the gastrointestinal tract. In addition, mice lacking CXCR4 die in utero and are defective in vascular development, haematopoiesis and cardiogenesis, like mice lacking PBSF/SDF-1, indicating that CXCR4 is a primary physiological receptor for PBSF/SDF-1. We conclude that PBSF/SDF-1 and CXCR4 define a new signalling system for organ vascularization.

Homologous recombination and non‐homologous end‐joining pathways of DNA double‐strand break repair have overlapping roles in the maintenance of chromosomal integrity in vertebrate cells

Abstract: Eukaryotic cells repair DNA double-strand breaks (DSBs) by at least two pathways, homologous recombination (HR) and non-homologous end-joining (NHEJ). Rad54 participates in the first recombinational repair pathway while Ku proteins are involved in NHEJ. To investigate the distinctive as well as redundant roles of these two repair pathways, we analyzed the mutants RAD54(-/-), KU70(-/-) and RAD54(-/-)/KU70(-/-), generated from the chicken B-cell line DT40. We found that the NHEJ pathway plays a dominant role in repairing gamma-radiation-induced DSBs during G1-early S phase while recombinational repair is preferentially used in late S-G2 phase. RAD54(-/-)/KU70(-/-) cells were profoundly more sensitive to gamma-rays than either single mutant, indicating that the two repair pathways are complementary. Spontaneous chromosomal aberrations and cell death were observed in both RAD54(-/-) and RAD54(-/-)/KU70(-/-) cells, with RAD54(-/-)/KU70(-/-) cells exhibiting significantly higher levels of chromosomal aberrations than RAD54(-/-) cells. These observations provide the first genetic evidence that both repair pathways play a role in maintaining chromosomal DNA during the cell cycle.

Cofilin phosphorylation by LIM-kinase 1 and its role in Rac-mediated actin reorganization

Abstract: Rac is a small GTPase of the Rho family that mediates stimulus-induced actin cytoskeletal reorganization to generate lamellipodia Little is known about the signalling pathways that link Rac activation to changes in actin filament dynamics Cofilin is known to be a potent regulator of actin filament dynamics, and its ability to bind and depolymerize actin is abolished by phosphorylation of serine residue at 3; however, the kinases responsible for this phosphorylation have not been identified Here we show that LIM-kinase 1 (LIMK-1), a serine/threonine kinase containing LIM and PDZ domains, phosphorylates cofilin at Ser 3, both in vitro and in vivo When expressed in cultured cells, LIMK-1 induces actin reorganization and reverses cofilin-induced actin depolymerization Expression of an inactive form of LIMK-1 suppresses lamellipodium formation induced by Rac or insulin Furthermore, insulin and an active form of Rac increase the activity of LIMK-1 Taken together, our results indicate that LIMK-1 participates in Rac-mediated actin cytoskeletal reorganization, probably by phosphorylating cofilin

Gabab-receptor subtypes assemble into functional heteromeric complexes

Abstract: B-type receptors for the neurotransmitter GABA (gamma-aminobutyric acid) inhibit neuronal activity through G-protein-coupled second-messenger systems, which regulate the release of neurotransmitters and the activity of ion channels and adenylyl cyclase. Physiological and biochemical studies show that there are differences in drug efficiencies at different GABA(B) receptors, so it is expected that GABA(B)-receptor (GABA(B)R) subtypes exist. Two GABA(B)-receptor splice variants have been cloned (GABA(B)R1a and GABA(B)R1b), but native GABA(B) receptors and recombinant receptors showed unexplained differences in agonist-binding potencies. Moreover, the activation of presumed effector ion channels in heterologous cells expressing the recombinant receptors proved difficult. Here we describe a new GABA(B) receptor subtype, GABA(B)R2, which does not bind available GABA(B) antagonists with measurable potency. GABA(B)R1a, GABA(B)R1b and GABA(B)R2 alone do not activate Kir3-type potassium channels efficiently, but co-expression of these receptors yields a robust coupling to activation of Kir3 channels. We provide evidence for the assembly of heteromeric GABA(B) receptors in vivo and show that GABA(B)R2 and GABA(B)R1a/b proteins immunoprecipitate and localize together at dendritic spines. The heteromeric receptor complexes exhibit a significant increase in agonist- and partial-agonist-binding potencies as compared with individual receptors and probably represent the predominant native GABA(B) receptor. Heteromeric assembly among G-protein-coupled receptors has not, to our knowledge, been described before.

Effects of sexual dimorphism on facial attractiveness

Abstract: Testosterone-dependent secondary sexual characteristics in males may signal immunological competence1 and are sexually selected for in several species2,3. In humans, oestrogen-dependent characteristics of the female body correlate with health and reproductive fitness and are found attractive4,5,6. Enhancing the sexual dimorphism of human faces should raise attractiveness by enhancing sex-hormone-related cues to youth and fertility in females5,7,8,9,10,11, and to dominance and immunocompetence in males5,12,13. Here we report the results of asking subjects to choose the most attractive faces from continua that enhanced or diminished differences between the average shape of female and male faces. As predicted, subjects preferred feminized to average shapes of a female face. This preference applied across UK and Japanese populations but was stronger for within-population judgements, which indicates that attractiveness cues are learned. Subjects preferred feminized to average or masculinized shapes of a male face. Enhancing masculine facial characteristics increased both perceived dominance and negative attributions (for example, coldness or dishonesty) relevant to relationships and paternal investment. These results indicate a selection pressure that limits sexual dimorphism and encourages neoteny in humans.

A single gene product, claudin-1 or -2, reconstitutes tight junction strands and recruits occludin in fibroblasts.

Abstract: Three integral membrane proteins, clau- din-1, -2, and occludin, are known to be components of tight junction (TJ) strands. To examine their ability to form TJ strands, their cDNAs were introduced into mouse L fibroblasts lacking TJs. Immunofluorescence microscopy revealed that both FLAG-tagged claudin-1 and -2 were highly concentrated at cell contact sites as planes through a homophilic interaction. In freeze-fracture replicas of these contact sites, well-developed networks of strands were identified that were similar to TJ strand networks in situ and were specifically labeled with anti-FLAG mAb. In glutaraldehyde-fixed samples, claudin-1–induced strands were largely associated with the protoplasmic (P) face as mostly continuous structures, whereas claudin-2–induced strands were discontinuous at the P face with complementary grooves at the extracellular (E) face which were occupied by chains of particles. Although occludin was also concentrated at cell contact sites as dots through its homophilic interaction, freeze-fracture replicas identified only a small number of short strands that were labeled with anti-occludin mAb. However, when occludin was cotransfected with claudin-1, it was concentrated at cell contact sites as planes to be incorporated into well- developed claudin-1–based strands. These findings suggested that claudin-1 and -2 are mainly responsible for TJ strand formation, and that occludin is an accessory protein in some function of TJ strands.

Progressive lineage analysis by cell sorting and culture identifies FLK1+VE-cadherin+ cells at a diverging point of endothelial and hemopoietic lineages

Abstract: Totipotent murine ES cells have an enormous potential for the study of cell specification. Here we demonstrate that ES cells can differentiate to hemopoietic cells through the proximal lateral mesoderm, merely upon culturing in type IV collagen-coated dishes. Separation of the Flk1+ mesoderm from other cell lineages was critical for hemopoietic cell differentiation, whereas formation of the embryoid body was not. Since the two-dimensionally spreading cells can be monitored easily in real time, this culture system will greatly facilitate the study of the mechanisms involved in the cell specification to mesoderm, endothelial, and hemopoietic cells. In the culture of ES cells, however, lineages and stages of differentiating cells can only be defined by their own characteristics. We showed that a combination of monoclonal antibodies against E-cadherin, Flk1/KDR, PDGF receptor(alpha), VE-cadherin, CD45 and Ter119 was sufficient to define most intermediate stages during differentiation of ES cells to blood cells. Using this culture system and surface markers, we determined the following order for blood cell differentiation: ES cell (E-cadherin+Flk1-PDGFRalpha-), proximal lateral mesoderm (E-cadherin-Flk1+VE-cadherin-), progenitor with hemoangiogenic potential (Flk1+VE-cadherin+CD45-), hemopoietic progenitor (CD45+c-Kit+) and mature blood cells (c-Kit-CD45+ or Ter119+), though direct differentiation of blood cells from the Flk1+VE-cadherin- stage cannot be ruled out. Not only the VE-cadherin+CD45- population generated from ES cells but also those directly sorted from the yolk sac of 9.5 dpc embryos have a potential to give rise to hemopoietic cells. Progenitors with hemoangiogenic potential were identified in both the Flk1+VE-cadherin- and Flk1+VE-cadherin+ populations by the single cell deposition experiment. This line of evidence implicates Flk1+VE-cadherin+ cells as a diverging point of hemopoietic and endothelial cell lineages.

Rad51‐deficient vertebrate cells accumulate chromosomal breaks prior to cell death

Abstract: Yeast rad51 mutants are viable, but extremely sensitive to gamma-rays due to defective repair of double-strand breaks. In contrast, disruption of the murine RAD51 homologue is lethal, indicating an essential role of Rad51 in vertebrate cells. We generated clones of the chicken B lymphocyte line DT40 carrying a human RAD51 transgene under the control of a repressible promoter and subsequently disrupted the endogenous RAD51 loci. Upon inhibition of the RAD51 transgene, Rad51- cells accumulated in the G2/M phase of the cell cycle before dying. Chromosome analysis revealed that most metaphase-arrested Rad51- cells carried isochromatid-type breaks. In conclusion, Rad51 fulfils an essential role in the repair of spontaneously occurring chromosome breaks in proliferating cells of higher eukaryotes.

Direct triggering of the type I interferon system by virus infection: activation of a transcription factor complex containing IRF‐3 and CBP/p300

Abstract: It has been hypothesized that certain viral infections directly activate a transcription factor(s) which is responsible for the activation of genes encoding type I interferons (IFNs) and interferon-stimulated genes (ISGs) via interferon regulatory factor (IRF) motifs present in their respective promoters. These events trigger the activation of defense machinery against viruses. Here we demonstrate that IRF-3 transmits a virus-induced signal from the cytoplasm to the nucleus. In unstimulated cells, IRF-3 is present in its inactive form, restricted to the cytoplasm due to a continuous nuclear export mediated by nuclear export signal, and it exhibits few DNA-binding properties. Virus infection but not IFN treatment induces phosphorylation of IRF-3 on specific serine residues, thereby allowing it to complex with the co-activator CBP/p300 with simultaneous nuclear translocation and its specific DNA binding. We also show that a dominant-negative mutant of IRF-3 could inhibit virus-induced activation of chromosomal type I IFN genes and ISGs. These findings suggest that IRF-3 plays an important role in the virus-inducible primary activation of type I IFN and IFN-responsive genes.

Time-reversal symmetry-breaking superconductivity in Sr2RuO4

Abstract: Although the properties of most superconducting materials are well described by the theory1 of Bardeen, Cooper and Schrieffer (BCS), considerable effort has been devoted to the search for exotic superconducting systems in which BCS theory does not apply. The transition to the superconducting state in conventional BCS superconductors involves the breaking of gauge symmetry only, whereby the wavefunction describing the Cooper pairs—the paired electron states responsible for superconductivity—adopt a definite phase. In contrast, a signature of an unconventional superconducting state is the breaking of additional symmetries2, which can lead to anisotropic pairing (such as the ‘d-wave’ symmetry observed in the copper oxide superconductors) and the presence of multiple superconducting phases (as seen in UPt3 and analogous behaviour in superfluid 3He; 3–5). Here we report muon spin-relaxation measurements on the superconductor Sr2RuO4 that reveal the spontaneous appearance of an internal magnetic field below the transition temperature: the appearance of such a field indicates that the superconducting state in this material is characterized by the breaking of time-reversal symmetry. These results, combined with other symmetry considerations, suggest that superconductivity in Sr2RuO4 is of ‘p-wave’ (odd-parity) type, analogous to superfluid 3He.

Spin-triplet superconductivity in Sr2RuO4 identified by 17O knight shift

Abstract: Superconductivity — one of the best understood many-body problems in physics — has again become a challenge following the discovery of unconventional superconducting materials: these include heavy-fermion1, organic2 and the high-transition-temperature copper oxide3 superconductors In conventional superconductors, the electrons form superconducting Cooper pairs in a spin-singlet state, which has zero total spin (S = 0) In principle, Cooper pairs can also form in a spin-triplet state (S = 1), analogous to the spin-triplet ‘p-wave’ state of paired neutral fermions in superfluid 3He (ref 4) At present, the heavy-fermion compound UPt3 is the only known spin-triplet superconductor5,6, although the layered oxide superconductor Sr2RuO4 (ref 7) is believed, on theoretical grounds8, to be a promising candidate The most direct means of identifying the spin state of Cooper pairs is from measurements of their spin susceptibility, which can be determined by the Knight shift (as probed by nuclear magnetic resonance (NMR)) Here we report Knight-shift measurements of Sr2RuO2 using 17O NMR Our results show no change in spin susceptibility on passing through the superconducting transition temperature, which provides the definitive identification of Sr2RuO4 as a spin-triplet superconductor

The distributed constraint satisfaction problem: formalization and algorithms

Abstract: We develop a formalism called a distributed constraint satisfaction problem (distributed CSP) and algorithms for solving distributed CSPs. A distributed CSP is a constraint satisfaction problem in which variables and constraints are distributed among multiple agents. Various application problems in distributed artificial intelligence can be formalized as distributed CSPs. We present our newly developed technique called asynchronous backtracking that allows agents to act asynchronously and concurrently without any global control, while guaranteeing the completeness of the algorithm. Furthermore, we describe how the asynchronous backtracking algorithm can be modified into a more efficient algorithm called an asynchronous weak-commitment search, which can revise a bad decision without exhaustive search by changing the priority order of agents dynamically. The experimental results on various example problems show that the asynchronous weak-commitment search algorithm is, by far more, efficient than the asynchronous backtracking algorithm and can solve fairly large-scale problems.

Genetic Restriction of AIDS Pathogenesis by an SDF-1 Chemokine Gene Variant

Abstract: Stromal-derived factor (SDF-1) is the principal ligand for CXCR4, a coreceptor with CD4 for T lymphocyte cell line-tropic human immunodeficiency virus-type 1 (HIV-1). A common polymorphism, SDF1-3'A, was identified in an evolutionarily conserved segment of the 3' untranslated region of the SDF-1 structural gene transcript. In the homozygous state, SDF1-3'A/3'A delays the onset of acquired immunodeficiency syndrome (AIDS), according to a genetic association analysis of 2857 patients enrolled in five AIDS cohort studies. The recessive protective effect of SDF1-3'A was increasingly pronounced in individuals infected with HIV-1 for longer periods, was twice as strong as the dominant genetic restriction of AIDS conferred by CCR5 and CCR2 chemokine receptor variants in these populations, and was complementary with these mutations in delaying the onset of AIDS.

Bose-Einstein Condensation with Internal Degrees of Freedom in Alkali Atom Gases

Abstract: The Bogoliubov theory is extended to a Bose-Einstein condensation with internal degrees of freedom, realized recently in 23 Na gases where several hyperfine states are simultaneously cooled optically. Starting with a Hamiltonian constructed from general gauge and spin rotation symmetry principles, fundamental equations for condensate are derived. The ground state where time reversal symmetry is broken in some cases and low-lying collective modes, e.g. spin and density wave modes, are discussed. Novel vortex as a topological defect can be created experimentally.

Efficient Presentation of Phagocytosed Cellular Fragments on the Major Histocompatibility Complex Class II Products of Dendritic Cells

Abstract: Cells from the bone marrow can present peptides that are derived from tumors, transplants, and self-tissues. Here we describe how dendritic cells (DCs) process phagocytosed cell fragments onto major histocompatibility complex (MHC) class II products with unusual efficacy. This was monitored with the Y-Ae monoclonal antibody that is specific for complexes of I-Ab MHC class II presenting a peptide derived from I-Eα. When immature DCs from I-Ab mice were cultured for 5–20 h with activated I-E+ B blasts, either necrotic or apoptotic, the DCs produced the epitope recognized by the Y-Ae monoclonal antibody and stimulated T cells reactive with the same MHC–peptide complex. Antigen transfer was also observed with human cells, where human histocompatibility leukocyte antigen (HLA)-DRα includes the same peptide sequence as mouse I-Eα. Antigen transfer was preceded by uptake of B cell fragments into MHC class II–rich compartments. Quantitation of the amount of I-E protein in the B cell fragments revealed that phagocytosed I-E was 1–10 thousand times more efficient in generating MHC–peptide complexes than preprocessed I-E peptide. When we injected different I-E– bearing cells into C57BL/6 mice to look for a similar phenomenon in vivo, we found that short-lived migrating DCs could be processed by most of the recipient DCs in the lymph node. The consequence of antigen transfer from migratory DCs to lymph node DCs is not yet known, but we suggest that in the steady state, i.e., in the absence of stimuli for DC maturation, this transfer leads to peripheral tolerance of the T cell repertoire to self.

Impaired febrile response in mice lacking the prostaglandin E receptor subtype EP3.

Abstract: Fever, a hallmark of disease, is elicited by exogenous pyrogens, that is, cellular components, such as lipopolysaccharide (LPS), of infectious organisms, as well as by non-infectious inflammatory insults Both stimulate the production of cytokines, such as interleukin (IL)-1β, that act on the brain as endogenous pyrogens1 Fever can be suppressed by aspirin-like anti-inflammatory drugs As these drugs share the ability to inhibit prostaglandin biosynthesis2, it is thought that a prostaglandin is important in fever generation Prostaglandin E2 (PGE2) may be a neural mediator of fever3, but this has been much debated1,4,5,6,7 PGE2 acts by interacting with four subtypes of PGE receptor, the EP1, EP2, EP3 and EP4 receptors8 Here we generate mice lacking each of these receptors by homologous recombination Only mice lacking the EP3 receptor fail to show a febrile response to PGE2 and to either IL-1β or LPS Our results establish that PGE2 mediates fever generation in response to both exogenous and endogenous pyrogens by acting at the EP3 receptor

The Cultural Psychology of Personality

Abstract: Research in cultural psychology suggests that person is a social and collective construction made possible through an individual's participation in the practices and meanings of a given cultural context. This perspective can make a contribution to some contemporary controversies in personality. In the current article, it is argued that although most conceptions of personality in academic psychology are rooted in a model of the person as independent, in many Asian cultures, personality is constructed on the basis of an alternative model of the person as interdependent. In these cultures, then, personality is experienced and understood as behavior that is characteristic of the person in relationship with others in particular social contexts. Some initial evidence is reviewed and questions for future research are suggested.

Ezrin/Radixin/Moesin (ERM) Proteins Bind to a Positively Charged Amino Acid Cluster in the Juxta-Membrane Cytoplasmic Domain of CD44, CD43, and ICAM-2

Abstract: . CD44 has been identified as a membrane-binding partner for ezrin/radixin/moesin (ERM) proteins, plasma membrane/actin filament cross-linkers. ERM proteins, however, are not necessarily colocalized with CD44 in tissues, but with CD43 and ICAM-2 in some types of cells. We found that glutathione-S-transferase fusion proteins with the cytoplasmic domain of CD43 and ICAM-2, as well as CD44, bound to moesin in vitro. The regions responsible for the in vitro binding of CD43 and CD44 to moesin were narrowed down to their juxta-membrane 20–30–amino acid sequences in the cytoplasmic domain. These sequences and the cytoplasmic domain of ICAM-2 (28 amino acids) were all characterized by the positively charged amino acid clusters. When E-cadherin chimeric molecules bearing these positively charged amino acid clusters of CD44, CD43, or ICAM-2 were expressed in mouse L fibroblasts, they were co-concentrated with ERM proteins at microvilli, whereas those lacking these clusters were diffusely distributed on the cell surface. The specific binding of ERM proteins to the juxta-membrane positively charged amino acid clusters of CD44, CD43, and ICAM-2 was confirmed by immunoprecipitation and site-directed mutagenesis. From these findings, we conclude that ERM proteins bind to integral membrane proteins bearing a positively charged amino acid cluster in their juxta-membrane cytoplasmic domain.

Occludin-deficient Embryonic Stem Cells Can Differentiate into Polarized Epithelial Cells Bearing Tight Junctions

Abstract: Occludin is the only known integral membrane protein of tight junctions (TJs), and is now believed to be directly involved in the barrier and fence functions of TJs. Occludin-deficient embryonic stem (ES) cells were generated by targeted disruption of both alleles of the occludin gene. When these cells were subjected to suspension culture, they aggregated to form simple, and then cystic embryoid bodies (EBs) with the same time course as EB formation from wild-type ES cells. Immunofluorescence microscopy and ultrathin section electron microscopy revealed that polarized epithelial (visceral endoderm-like) cells were differentiated to delineate EBs not only from wild-type but also from occludin-deficient ES cells. Freeze fracture analyses indicated no significant differences in number or morphology of TJ strands between wild-type and occludin-deficient epithelial cells. Furthermore, zonula occludens (ZO)-1, a TJ-associated peripheral membrane protein, was still exclusively concentrated at TJ in occludin-deficient epithelial cells. In good agreement with these morphological observations, TJ in occludin-deficient epithelial cells functioned as a primary barrier to the diffusion of a low molecular mass tracer through the paracellular pathway. These findings indicate that there are as yet unidentified TJ integral membrane protein(s) which can form strand structures, recruit ZO-1, and function as a barrier without occludin.

Modulation of cell death by Bcl-XL through caspase interaction.

Abstract: The caspases are cysteine proteases that have been implicated in the execution of programmed cell death in organisms ranging from nematodes to humans. Many members of the Bcl-2 family, including Bcl-xL, are potent inhibitors of programmed cell death and inhibit activation of caspases in cells. Here, we report a direct interaction between caspases and Bcl-xL. The loop domain of Bcl-xL is cleaved by caspases in vitro and in cells induced to undergo apoptotic death after Sindbis virus infection or interleukin 3 withdrawal. Mutation of the caspase cleavage site in Bcl-xL in conjunction with a mutation in the BH1 homology domain impairs the death-inhibitory activity of Bcl-xL, suggesting that interaction of Bcl-xL with caspases may be an important mechanism of inhibiting cell death. However, once Bcl-xL is cleaved, the C-terminal fragment of Bcl-xL potently induces apoptosis. Taken together, these findings indicate that the recognition/cleavage site of Bcl-xL may facilitate protection against cell death by acting at the level of caspase activation and that cleavage of Bcl-xL during the execution phase of cell death converts Bcl-xL from a protective to a lethal protein.

Endothelial Nitric Oxide Synthase Gene Is Positively Associated With Essential Hypertension

Abstract: Essential hypertension has a genetic basis. Accumulating evidence, including findings of elevation of arterial blood pressure in mice lacking the endothelial nitric oxide synthase (eNOS) gene, strongly suggests that alteration in NO metabolism is implicated in hypertension. There are, however, no reports indicating that polymorphism in the eNOS gene is associated with essential hypertension. We have identified a missense variant, Glu298Asp, in exon 7 of the eNOS gene and demonstrated that it is associated with both coronary spastic angina and myocardial infarction. To explore the genetic involvement of the eNOS gene in essential hypertension, we examined the possible association between essential hypertension and several polymorphisms including the Glu298Asp variant, variable number tandem repeats in intron 4 (eNOS4b/4a), and two polymorphisms in introns 18 and 23. We performed a large-scale study of genetic association using two independent populations from Kyoto (n=458; 240 normotensive versus 218 hypertensive subjects) and Kumamoto (n=421; 223 normotensive versus 187 hypertensive subjects), Japan. In both groups, a new coding variant, Glu298Asp, showed a strong association with essential hypertension (Kyoto: odds ratio, 2.3 [95% confidence interval, 1.4 to 3.9]; Kumamoto: odds ratio, 2.4 [95% confidence interval, 1.4 to 4.0]). The allele frequencies of 298Asp in hypertensive subjects were significantly higher than those in normotensive subjects in both groups (Kyoto: 0.103 versus 0.050, P<0.0017; Kumamoto: 0.120 versus 0.058, P<0.0013, respectively). No such disequilibrium between genotypes was significantly associated with any other polymorphisms we examined; the Glu298Asp variant was also not linked to any other polymorphisms. In conclusion, the Glu298Asp missense variant was significantly associated with essential hypertension, which suggests that it is a genetic susceptibility factor for essential hypertension.