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M Suda

Publications and source records attributed to M Suda.

At least 37 records · Page 2Linked to original sources
PubMed2000

Regulation of Wee1 kinase in response to protein synthesis inhibition.

To investigate the mechanism coupling growth (protein synthesis) with cell division, we examined the relationship between the tyrosine kinase Wee1 that inhibits Cdc2-Cdc13 mitosis-inducing kinase by phosphorylating it, and protein synthesis inhibition in fission yeast. The wee1-50 mutant showed supersensitivity to protein synthesis inhibitor, cycloheximide. Wee1 was essential for the G(2) delay upon a partial inhibition of protein synthesis. Indeed, the protein synthesis inhibition caused an increase in the Wee1 protein by the Sty1/Spc1 MAPK-dependent transcriptional and the Sty1/Spc1 MAPK-independent post-transcriptional regulations. Further, the results indicated that the post-transcriptional regulation is important for the G(2) delay.

CDC2 Protein Kinase↗
PubMed2000

Cardiac fibrosis in mice lacking brain natriuretic peptide.

Cardiac fibrosis, defined as a proliferation of interstitial fibroblasts and biosynthesis of extracellular matrix components in the ventricles of the heart, is a consequence of remodeling processes initiated by pathologic events associated with a variety of cardiovascular disorders, which leads to abnormal myocardial stiffness and, ultimately, ventricular dysfunction. Brain natriuretic peptide (BNP) is a cardiac hormone produced primarily by ventricular myocytes, and its plasma concentrations are markedly elevated in patients with congestive heart failure and acute myocardial infarction. However, its precise functional significance has been undefined. In this paper, we report the generation of mice with targeted disruption of BNP (Nppb(-/-) mice). We observed multifocal fibrotic lesions in the ventricles from Nppb(-/-) mice. No signs of systemic hypertension and ventricular hypertrophy are noted in Nppb(-/-) mice. In response to ventricular pressure overload, focal fibrotic lesions are increased in size and number in Nppb(-/-) mice, whereas no focal fibrotic changes are found in wild-type littermates (Nppb(+/+) mice). This study establishes BNP as a cardiomyocyte-derived antifibrotic factor in vivo and provides evidence for its role as a local regulator of ventricular remodeling.

Animals↗
PubMed2000

Prostaglandin E(2) (PGE(2)) induces the c-fos and c-jun expressions via the EP(1) subtype of PGE receptor in mouse osteoblastic MC3T3-E1 cells.

This study examined which subtype(s) of PGE receptors is involved in the induction of c-fos and c-jun by PGE(2) in MC3T3-E1 cells. We also investigated the possibility that the induction of these genes is involved in the growth and differentiation of this cell line. PGE(2) dose-dependently induced c-fos and c-jun mRNA expressions in MC3T3-E1 cells. Of the PGE analogs, 17-phenyl-omega-trinor PGE(2) (EP(1) agonist) and sulprostone (EP(1)/EP(3) agonist) were far more potent than butaprost (EP(2) agonist) and 11-deoxy PGE(1) (EP(2)/EP(4) agonist) in inducing c-fos and c-jun mRNA expressions. Since MC3T3-E1 cells do not express the EP(3) subtype, these results suggest that PGE(2) induces c-fos and c-jun mRNA expressions through the EP(1) subtype of its receptor. In order to study the functional relevance of these protooncogenes, we then studied the effect of inhibition of their synthesis by the use of antisense oligonucleotide. Alkaline phosphatase (ALP) suppression by 17-phenyl-omega-trinor PGE(2) was reversed by antisense oligonucleotide for either c-fos or c-jun. These results suggest that PGE(2), via the EP(1) subtype of the PGE receptor, negatively modulates the transition from proliferation to the matrix maturation stage through the induction of c-fos and c-jun. However, antisense oligonucleotide for c-fos or c-jun did not alter the prostaglandin G/H synthase-2 mRNA expression induced by EP(1). Thus, it is possible that c-fos and c-jun inductions do not account for all the EP(1)-mediated PGE(2) actions in MC3T3-E1 cells.

Alkaline Phosphatase↗
PubMed2000

Proliferation and cell death of embryonic primitive erythrocytes.

Erythropoietin (EPO) is the principal regulator for the production of adult-type definitive erythrocytes (EryD). EPO not only stimulates both the proliferation and differentiation of EryD progenitors, but also maintains the viability of EryD progenitors. Compared to the abundant knowledge about the function of EPO in EryD production, the roles of EPO in the production of embryonic-type primitive erythrocytes (EryP) are less clear. The effects of EPO on EryP proliferation and differentiation were investigated using EryP purified from developing mouse embryos and the cells obtained from mouse embryonic stem cells using an in vitro differentiation induction. Immature EryP of both in vivo and in vitro origin responded to EPO stimulation and underwent apoptosis with EPO deprivation. In contrast, there were no significant differences between the cultures with and without EPO, when fully mature EryP were examined, that is, EryP lost its dependency on EPO stimulation with maturation. These results show that EPO functions as a survival factor for immature embryonic EryP as well as immature EryD progenitors.

Animals↗
PubMed2000

Thrombopoietic activity of recombinant human interleukin-11 in nonhuman primates with ACNU-induced thrombocytopenia.

The effect of recombinant human interleukin-11 (rHuIL-11) on myelosuppressive nimustine (ACNU)-induced thrombocytopenia was assessed in nonhuman primates. A single intravenous (i.v.) injection of ACNU (15 mg/kg) was administered to cynomolgus monkeys on day 0. rHuIL-11 (100 microg/kg/day) or the vehicle was given subcutaneously (s.c.) from day 1 to day 21. In monkeys receiving ACNU, the circulating platelet count decreased to a low of 42 +/- 6 x 10(9)/L by day 21 but returned to pretreatment levels (375 +/- 48 x 10(9)/L) on day 30. Administration of rHuIL-11 prevented severe thrombocytopenia; the platelet count fell only to 138 +/- 23 x 10(9)/L on day 18, and platelet recovery was faster (458 +/- 91 x 10(9)/L by day 27) compared with that of the control animals. The size of bone marrow megakaryocytes from rHuIL-11-treated animals was larger than that of the controls, indicating that rHuIL-11 stimulated megakaryopoiesis in a myelosuppressive condition. Treatment with ACNU also caused leukopenia and moderate anemia. rHuIL-11 transiently and slightly decreased the white blood cell (WBC) and red blood cell (RBC) counts. Conversely, rHuIL-11 accelerated recovery of RBC count in the late administration period. These results support the assertion that rHuIL-11 may be an important therapeutic agent for reducing the severity and duration of thrombocytopenia following cancer chemotherapy.

Animals↗
PubMed2000

Impaired bone resorption by lipopolysaccharide in vivo in mice deficient in the prostaglandin E receptor EP4 subtype.

In a previous study we showed that the involvement of EP4 subtype of the prostaglandin E (PGE) receptor is crucial for lipopolysaccharide (LPS)-induced osteoclast formation in vitro. The present study was undertaken to test whether EP4 is actually associated with LPS-induced bone resorption in vivo. In wild-type (WT) mice, osteoclast formation in vertebrae and tibiae increased 5 days after systemic LPS injection, and urinary excretion of deoxypyridinoline, a sensitive marker for bone resorption, statistically increased 10 days after injection. In EP4 knockout (KO) mice, however, LPS injection caused no significant changes in these parameters throughout the experiment. LPS exposure for 4 h strongly induced osteoclast differentiation factor (ODF) mRNA expression in primary osteoblastic cells (POB) both from WT and EP4 KO mice, and this expression was not inhibited by indomethacin, suggesting prostaglandin (PG) independence. LPS exposure for 24 h further induced ODF expression in WT POB, but not in EP4 KO POB. Indomethacin partially inhibited ODF expression in WT POB, but not in EP4 KO POB. These data suggest that ODF is induced both PG dependently and PG independently. LPS exposure for 24 h induced slightly greater osteoclastgenesis inhibitory factor (OCIF) mRNA expression in EP4 KO than in WT POB. These findings suggest that the reduced ODF expression and apparently increased OCIF expression also are responsible for the markedly reduced LPS-induced osteoclast formation in EP4 KO mice. Our results show that the EP4 subtype of the PGE receptor is involved in LPS-induced bone resorption in vivo also. Since LPS is considered to be largely involved in bacterially induced bone loss, such as in periodontitis and osteomyelitis, our study is expected to help broaden our understanding of the pathophysiology of these conditions.

Animals↗
PubMed2000

Influence of 2-bromopropane on reproductive system--short-term administration of 2-bromopropane inhibits ovulation in F344 rats.

The present study was performed to investigate the toxic effects of 2-bromopropane (2BP) on the female reproductive system. Female F344 rats were administered 2BP (500 or 1000 mg/kg, i.p.) at intervals of 2 or 3 days for 15-17 days. The body weights were measured and estrous stages were observed throughout the experimental period. Ovulation, organ weights, ovarian histology, and blood biochemistry were investigated on the terminal day of the experiment. Uterine weights in rats treated with 2BP were significantly lower than those in control animals. Body, liver, kidney, and adrenal weights in 2BP-treated rats showed no significant differences from control values. 2BP treatment prolonged estrous cycles and decreased the number of ovulated ova in spontaneous ovulation. In addition, histological examinations showed that the preovulatory follicles in the ovary were altered markedly in 2BP groups. These results show that even in short-term treatment, 2BP injured the ovary, particularly the preovulatory follicles. It appears that these damages of the preovulatory follicles induced by 2BP reduced the numbers of spontaneously ovulated ova in female F344 rats.

Amylases↗
PubMed2000

Genetic models reveal that brain natriuretic peptide can signal through different tissue-specific receptor-mediated pathways.

Brain natriuretic peptide (BNP), a hormone produced primarily by the cardiac ventricle, is thought to be involved in a variety of homeostatic processes through its cognate receptor, guanylyl cyclase A (GC-A). We previously created transgenic mice overexpressing BNP under the control of the liver-specific human serum amyloid P component promoter (BNP-transgenic mice) and demonstrated that they exhibit reduced blood pressure and cardiac weight accompanied by an elevation of plasma cGMP concentrations and marked skeletal overgrowth through the activation of endochondral ossification. To address whether BNP exerts its biological effects solely through GC-A, we produced BNP-transgenic mice lacking GC-A (BNP-Tg/GC-A-/- mice) and examined their cardiovascular and skeletal phenotypes. The GC-A-/- mice are hypertensive with cardiac hypertrophyrelative to wild-type littermates, which is not alleviated by overexpression of BNP in BNP-Tg/GC-A-/- mice. The BNP-Tg/GC-A-/- mice, however, continue to exhibit marked longitudinal growth of vertebrae and long bones comparably to BNP-Tg mice. This study provides genetic evidence that BNP reduces blood pressure and cardiac weight through GC-A, whereas it dramatically alters endochondral ossification in the absence of this receptor. Therefore, the BNP-Tg/GC-A-/- mice provide the first experimental model demonstrating that this natriuretic peptide can signal in a tissue-specific manner through a receptor other than GC-A.

Animals↗
PubMed2000

Crucial involvement of the EP4 subtype of prostaglandin E receptor in osteoclast formation by proinflammatory cytokines and lipopolysaccharide.

Prostaglandin E2 (PGE2) exerts its effects through the PGE receptor that consists of four subtypes (EP1, EP2, EP3, and EP4). Osteoclast formation in the coculture of primary osteoblastic cells (POB) and bone marrow cells was enhanced more by 11-deoxy-PGE1 (an EP4 and EP2 agonist) than by butaprost (an EP2 agonist) and other agonists, which suggests that EP4 is the main factor in PGE2-induced osteoclast formation. PGE2-induced osteoclast formation was not observed in the coculture of POB from EP4-deficient (EP4 k/o) mice and spleen cells from wild-type (w/t) mice, whereas osteoclasts were formed in the coculture of POB from w/t mice and spleen cells from EP4-k/o mice. In situ hybridization (ISH) showed that EP4 messenger RNA (mRNA) was expressed on osteoblastic cells but not on multinucleated cells (MNCs) in w/t mice. These results indicate that PGE2 enhances osteoclast formation through its EP4 subtype on osteoblasts. Osteoclast formation by interleukin 1alpha (IL-1alpha), tumor necrosis factor alpha (TNF-alpha), basic fibroblast growth factor (bFGF), and lipopolysaccharide (LPS) was hardly observed in the coculture of POB and bone marrow cells, both from EP4-k/o mice, which shows the crucial involvement of PG and the EP4 subtype in osteoclast formation by these molecules. In contrast, osteoclast formation by 1,25-hydroxyvitamin D3 (1,25(OH)2D3) was not impaired and that by parathyroid hormone (PTH) was only partially impaired in EP4-k/o mice, which may be related to the fact that EP4-k/o mice revealed no gross skeletal abnormalities. Because it has been suggested that IL-1alpha, TNF-alpha, bFGF, and LPS are involved in inflammatory bone loss, our work can be expected to contribute to an understanding of the pathophysiology of these conditions.

Animals↗
PubMed2000

Functional significance of prop-1 gene expression in pituitary adenomas.

Prophet of Pit-1 (Prop-1), which is a paired-like homeodomain transcription factor, is capable of binding to sites in an early enhancer of the Pit-1 gene and regulating its expression. As human Pit-1 is expressed considerably in pituitary adenomas, we studied human Prop-1 gene expression in pituitary adenomas. We also sequenced the Prop-1 cDNAs in pituitary adenomas. Human Prop-1 transcript was detected in all pituitary adenomas examined by RT-PCR analysis. The expression of human Prop-1 in pituitary adenomas was confirmed by in situ hybridization in one of the GH-producing adenomas. The sequence analysis of human Prop-1 cDNAs in these pituitary adenomas revealed that there were no mutations except 5 silent nucleic acid substitutions, suggesting that mutations of Prop-1 gene do not represent a frequent mechanism of human pituitary tumorigenesis.

Adenoma↗
PubMed1999

Absorption of Polyelectrolytes on Colloidal Surfaces as Studied by Electrophoretic and Dynamic Light-Scattering Techniques.

zeta-Potential and the effective diameter of the colloidal spheres absorbed with the macro-cations and macro-anions are studied by the electrophoretic light-scattering and dynamic light-scattering measurements. Colloidal spheres used are monodispersed polystyrene (220 nm in diameter) and colloidal silica spheres (110 nm). Macro-ions used are sodium polyacrylate, sodium polymethylacrylate, sodium poly(styrene sulfonate), and poly-4-vinyl pyridines quaternized with ethyl bromide, n-butyl bromide, benzyl chloride, and 5% hexadecyl bromide and 95% benzyl chloride. Reversal of colloidal surface charges from negative to positive occurs abruptly above the critical concentration of macro-ions by the excess absorption of the macro-cations onto the anionic colloidal spheres, i.e., avalanche-type absorption. The effective diameter of colloidal spheres including the absorbed layers increases substantially by four- to tenfold. In the presence of large amount of macro-cations aggregation of colloidal spheres mediated by the layers of absorbed macro-cations may occur. Absorption also occurs on the anionic colloidal spheres in the presence of an excess amount of macro-anions by the dipole-dipole-type attractive interactions. Copyright 1999 Academic Press.

Journal Article↗
PubMed1999

Structural and functional abnormalities in the spleen of an mFtz-F1 gene-disrupted mouse.

The spleen has two main functions. The first is to provide a proper microenvironment to lymphoid and myeloid cells, whereas the second involves clearance of abnormal erythrocytes. Ad4BP/SF-1, a product of the mammalian FTZ-F1 gene (mFTZ-F1), was originally identified as a steroidogenic, tissue-specific transcription factor. Immunohistochemical examination of the mammalian spleens confirmed the expression of Ad4BP/SF-1 in endothelial cells of the splenic venous sinuses and pulp vein. In mFtz-F1 gene-disrupted (KO) mice, several structural abnormalities were detected in the spleen, including underdevelopment and nonuniform distribution of erythrocytes. Examination of the spleen of KO fetuses showed failure of development of certain tubular structures during embryogenesis. These structures are normally assembled by Ad4BP/SF-1 immunoreactive cells, and most likely form the vascular system during later stages of development. Other structural abnormalities in the spleen of the KO mice included defects in the tissue distribution of type-IV collagen, laminin, c-kit, and vimentin. These morphologic defects in the vascular system were associated with a decrease in the proportion of hematopoietic cells, although differentiation of these cells was not affected significantly. A high number of abnormal red blood cells containing Howell-Jolly bodies were noted in the KO mice, indicating impaired clearance by the splenic vascular system. We also detected the presence of an mRNA-encoding cholesterol side-chain cleavage P450 in the spleen, resembling the findings in steroidogenic tissues such as the gonads and adrenal cortex. The mRNA transcript was not involved in splenic structural defects as it was detected in the spleens of both normal and KO mice, indicating that the regulatory mechanism of the P450 gene in the spleen is different from that in steroidogenic tissues. Our results indicate that a lack of the mFtz-F1 gene in mice is associated with structural and functional abnormalities of the splenic vascular system.

Animals↗
PubMed1999

C-Type natriuretic peptide/guanylate cyclase B system in rat osteogenic ROB-C26 cells and its down-regulation by dexamethazone.

There is recent evidence that natriuretic peptides are important regulators of bone and cartilage, although they were originally identified as the cardiac hormones causing natriuresis and hypotension. Three members of natriuretic peptide family are known: atrial natriuretic peptide (ANP), brain natriuretic peptide (BNP), and C-type natriuretic peptide (CNP). The biologically active receptors for these peptides are particulate guanylate cyclases; the two known types are GC-A and GC-B. ANP and BNP have high affinities for GC-A, and CNP is the preferred ligand for GC-B. In this paper we report the results of our study of the expression and possible role(s) of natriuretic peptides in the ROB-C26 cell, which is an osteogenic cell line with multiple potentials for differentiating into myoblast, osteoblast, and adipocyte. ROB-C26 cells produced cGMP in response to natriuretic peptides at both their basal state and after enhanced differentiation into osteoblast which was induced by bone morphogenetic protein [(BMP)-2]. CNP was far more potent than ANP in cGMP production. In contrast, enhanced differentiation into adipocyte by dexamethasone resulted in the marked decrease in their responsiveness to natriuretic peptides. Although the messages for GC-A and GC-B were demonstrated by Northern blot analysis at both the basal stage and after BMP treatment, they were down-regulated after dexamethasone treatment. The presence of CNP was shown by RT-PCR and immunohistochemistry in ROB-C26 cells. C3H10T1/2, which is another and more primitive mesenchymal cell line, also produced cGMP in response to CNP, and less potently to ANP. Culturing ROB-C26 cells with CNP or 8-bromo cGMP decreased [(3)H]thymidine uptake and slightly increased the message for alkaline phosphatase, which is a marker for osteoblast differentiation. These results suggest that the CNP/GC-B system is preferentially expressed in the cells of osteogenic lineage and their expression is down-regulated with differentiation into adipocyte lineage. The CNP/GC-B system is likely to be an autocrine/paracrine regulator of osteoblast growth and differentiation.

Alkaline Phosphatase↗
PubMed1999

Vimentin intermediate filament protein as differentiation marker of optic vesicle epithelium in the chick embryo.

For the study of the differentiation process of optic vesicle epithelium into neural retina, pigment epithelium and pars caeca retinae, vimentin intermediate filament protein in retinal epithelial cells was detected immunohistochemically in chick embryo at stages 11-21. In the late stage of optic vesicle development (stage 14), optic vesicle epithelium was classified into the following 3 different portions on the basis of vimentin staining intensity: latero-central epithelium under the lens placode, medio-central epithelium facing the latero-central epithelium, and peripheral epithelium connecting the latero-central and medio-central epithelia. Latero-central epithelium, the future neural retina, exhibited strongest staining of vimentin of the 3 portions. In contrast, medio-central epithelium, the future pigment epithelium, showed weakest staining. Moderate staining was observed in peripheral epithelium, the future pars caeca retinae. These differences in levels of vimentin expression were observed during optic cup formation. The present results clearly demonstrate that differentiation of retinal epithelium into neural retina, pigment epithelium and pars caeca retinae occurs in the late stage of the optic vesicle, and that retinal differentiation is reflected by the amount of vimentin in epithelial cells.

Animals↗
PubMed1999

Overproduction of elongation factor 1alpha, an essential translational component, causes aberrant cell morphology by affecting the control of growth polarity in fission yeast.

BACKGROUND: Elongation factor 1alpha (EF1alpha), an essential component of the eukaryotic translational machinery, has been shown to possess various biochemical and biological activities, including F-actin-binding and -bundling, microtubule- severing, and the activity of making fibroblasts highly susceptible to transformation. However, our understanding of the biological significance of EF1alpha with respect to these various biochemical or biological activities remains limited. Here we report the identification of EF1alpha-encoding genes as genes whose over-expression causes aberrant cell morphology in fission yeast. RESULTS: Overproduction of EF1alpha caused aberrant cell morphology-elliptic, curved or branched-and growth defects in yeast cells at high temperatures. EF1alpha-overproducing cells showed a supersensitivity to the actin inhibitor cytochalasin D and to the tubulin inhibitor thiabendazole. Genetic analyses using cdc mutants suggested that excess EF1alpha disturbed the establishment and the maintenance of growth polarity in the G1 phase by pre- venting the localization of F-actin to the polarized growing site and the organization of microtubules. Results from DNase I column chromatography indicated that EF1alpha was bound to G-actin. Indeed, the fission yeast actin was immunoprecipitated along with EF1alpha. Moreover, the temperature sensitivity caused by the overproduction of EF1alpha was restored by co-overproduction of actin. CONCLUSIONS: Fission yeast EF1alpha has the ability to alter the cell morphology of yeast by affecting the control of actin and microtubule cytoskeletons.

Actins↗
PubMed1999

Characterization of Prophet of Pit-1 gene expression in normal pituitary and pituitary adenomas in humans.

Prophet of Pit-1 (Prop-1), which is a paired-like homeodomain transcription factor, is capable of binding to sites in an early enhancer of the Pit-1 gene and regulating its expression. According to a previous report, Prop-1 messenger RNA (mRNA) is expressed in the developing pituitary gland before Pit-1 mRNA expression and maximum expression are observed at e 12.0. After e 14.5, Prop-1 mRNA expression rapidly decreases, and only trace amounts of mRNA are detectable in adult mouse pituitary. Human Pit-1 is expressed considerably, not only in normal adult pituitary but also in pituitary adenomas, so we studied human Prop-1 gene expression in adult pituitary and pituitary adenomas. We also cloned human Prop-1 complementary DNA (cDNA) and sequenced the Prop-1 cDNAs in pituitary adenomas. The amino acid sequence of human Prop-1 cDNA that we cloned was identical to that of the previously reported sequence, except Thr substituted at codon 142 instead of Ala. This amino acid substitution is considered to be a polymorphism because it did not alter transcriptional activity, and 7 of 28 alleles were Ala. Human Prop-1 transcript was detected in normal adult pituitary, by Northern blot analysis, and in all pituitary adenomas examined by RT-PCR analysis. The expression of human Prop-1 in pituitary adenomas was confirmed by in situ hybridization in one of the somatotroph adenomas. The sequence analysis of human Prop-1 cDNAs in these pituitary adenomas revealed that there were no mutations, except 5 silent nucleic acid substitutions, suggesting that mutations of Prop-1 gene do not represent a frequent mechanism of human pituitary tumorigenesis.

Adenoma↗
PubMed1999

Increased glucose metabolism and insulin sensitivity in transgenic skinny mice overexpressing leptin.

Excess of body fat, or obesity, is a major health problem and confers a higher risk of cardiovascular and metabolic disorders such as diabetes, hypertension, and coronary heart disease. Leptin is an adipocyte-derived satiety factor that plays an important role in the regulation of energy homeostasis, and its synthesis and secretion are markedly increased in obese subjects. To explore the metabolic consequences of an increased amount of leptin on a long-term basis in vivo, we generated transgenic skinny mice with elevated plasma leptin concentrations comparable to those in obese subjects. Overexpression of leptin in the liver has resulted in complete disappearance of white and brown adipose tissue for a long period of time in mice. Transgenic skinny mice exhibit increased glucose metabolism accompanied by the activation of insulin signaling in the skeletal muscle and liver. They also show small-sized livers with a marked decrease in glycogen and lipid storage. The phenotypes are in striking contrast to those of recently reported animal models of lipoatrophic diabetes and patients with lipoatrophic diabetes with reduced amount of leptin. The present study provides evidence that leptin is an adipocyte-derived antidiabetic hormone in vivo and suggests its pathophysiologic and therapeutic implications in diabetes.

Animals↗