Biomedical subjects

M Yanagisawa

Publications and source records attributed to M Yanagisawa.

At least 37 records · Page 2Linked to original sources

PubMed2001

Signaling crosstalk underlying synergistic induction of astrocyte differentiation by BMPs and IL-6 family of cytokines.

We here show that bone morphogenetic protein (BMP) 7 acted in synergy with the distinct type of cytokines, leukemia inhibitory factor (LIF) and interleukin (IL) 6 that are in the IL-6 family, to induce astrocyte differentiation from neuroepithelial cells as assessed by expression of glial fibrillary acidic protein (GFAP). In this synergistic action, transcription factors, Smads and STAT3 (for signal transducer and activator of transcription 3) activated by respective group of cytokines, as well as a transcriptional coactivator p300 were essential. Taken together with our previous finding that the synergistic astrocyte induction by BMP2 and LIF is attributed to the complex formation of Smads and STAT3 bridged by p300, it is conceivable that this complex formation is a mechanism utilized in common by two different types of cytokines belonging to the BMP and IL-6 families in order to synergistically induce astrocyte differentiation.

Animals↗

PubMed2001

The CDCREL1 gene fused to MLL in de novo acute myeloid leukemia with t(11;22)(q23;q11.2) and its frequent expression in myeloid leukemia cell lines.

We report on an adult patient with de novo acute myeloid leukemia (AML) with a t(11;22)(q23;q11.2) involving CDCREL1 and MLL genes. Reverse transcriptase (RT)-polymerase chain reaction (PCR) followed by direct sequencing analysis revealed the MLL-CDCREL1 fusion transcript in his leukemic cells. Analysis of the fusion transcript showed that exon 6 of MLL was fused to exon 4 of CDCREL1, which contains an AT-hook domain of MLL and a GTP binding domain of CDCREL1. To investigate the roles of CDCREL1 further, we examined the expression of the CDCREL1 gene in various cell lines. Expression of CDCREL1 was detected in 11 (85%) of 13 AML cell lines and 3 (21%) of 14 acute lymphoblastic leukemia (ALL) cell lines, but none of 11 EB virus transformed B-cell lines by RT-PCR. The expression rate of CDCREL1 was significantly higher in AML cell lines than in ALL cell lines (P = 0.0035). Platelet glycoprotein 1B beta (GP1B beta), which is located downstream of CDCREL1 and is cotranscribed with CDCREL1 due to a nonconsensus polyadenylation sequence, was expressed in all these cell lines. The higher expression rate of CDCREL1 in AML cell lines than in ALL cell lines suggests that this gene may play some role in myeloid leukemogenesis.

Adult↗

PubMed2001

t(10;11)-acute leukemias with MLL-AF10 and MLL-ABI1 chimeric transcripts: specific expression patterns of ABI1 gene in leukemia and solid tumor cell lines.

The recurrent translocation t(10;11) is associated with acute myeloid leukemia (AML). The AF10 gene on chromosome 10 at band p12 and MLL at 11q23 fuse in the t(10;11)(p12;q23). Recently, we have identified ABI1 as a new partner gene for MLL in an AML patient with a t(10;11)(p11.2;q23). The ABI1 is a human homologue of the mouse Abl-interactor 1 (Abi1), encoding an Abl-binding protein. The ABI1 protein exhibits sequence similarity to homeotic genes, and contains several polyproline stretches and a src homology 3 (SH3) domain. To clarify the clinical features of t(10;11)-leukemias, we investigated 6 samples from acute leukemia patients with t(10;11) and MLL rearrangement and detected MLL-AF10 chimeric transcripts in 5 samples and MLL-ABI1 in one. The patient with MLL-ABI1 chimeric transcript is the second case described, thus confirming that the fusion of the MLL and ABI1 genes is a recurring abnormality. Both of the patients with MLL-ABI1 chimeric transcript are surviving, suggesting that these patients have a better prognosis than the patients with MLL-AF10. To investigate the roles of AF10 and ABI1 further, we examined the expression of these genes in various cell lines and fresh tumor samples using the reverse transcriptase-polymerase chain reaction method. Although AF10 was expressed in almost all cell lines similarly, the expression patterns of ABI1 were different between leukemia and solid tumor cell lines, suggesting the distinctive role of each isoform of ABI1 in these cell lines. We also determined the complete mouse Abi1 sequence and found that the sequence matched with human ABI1 better than the originally reported Abi1 sequence. Further functional analysis of the MLL-AF10 and MLL-ABI1 fusion proteins will provide new insights into the leukemogenesis of t(10;11)-AML.

Acute Disease↗

PubMed2001

Normal ventilation and ventilatory responses to chemical stimuli in juvenile mutant mice deficient in endothelin-3.

Congenital central hypoventilation syndrome (CCHS) and Hirschsprung's disease (HSCR) are often classified as neurocristopathies and are thought to share a common molecular pathogenesis related to the genes that control the development of neural crest cells. We examined whether endothelin-3 (ET-3), one of the developmental regulators of neural crest cells and of which null mutation results in aganglionic megacolon in mice, fulfills the requirements for such a common molecule. To investigate the possible involvement of ET-3 in central ventilatory control, we measured ventilation in mutant mice deficient in ET-3 by whole body plethysmography. Tidal volume and breathing frequency were measured during breathing of room air, hypoxic, hyperoxic, or hypercapnic gas mixtures in awake and anesthetized mice. There were no significant differences in resting ventilation as well as ventilatory responses to hypoxia and hypercapnia between ET-3-knockout mice and wild-type mice. Our results indicate that ET-3 can not be considered as a common pathogenic mechanism for CCHS and HSCR at least in mice.

Anesthesia↗

PubMed2001

Fate alteration of neuroepithelial cells from neurogenesis to astrocytogenesis by bone morphogenetic proteins.

Bone morphogenetic proteins (BMPs), a class of cytokines belonging to the transforming growth factor-beta superfamily, have been shown to play a wide variety of roles during development including those in the central nervous system. We here report that BMP2, BMP4 and BMP7 have an equivalent potential to inhibit neurogenesis and concomitantly induce astrocytogenesis of mouse fetal neuroepithelial cells. We further show that these BMPs activate a promoter of the gene for negative helix-loop-helix (HLH) factor, Id1, which is known to inhibit the function of such neurogenic transcription factors as Mash1 and neurogenin. These results suggest that BMP2, BMP4 and BMP7 alternate the fate of neuroepithelial cells from neuronal type to astrocytic one via a common mechanism involving negative HLH factor.

Activin Receptors, Type I↗

PubMed2001

Varicella-associated acute necrotizing encephalopathy with a good prognosis.

A patient with acute necrotizing encephalophathy (ANE) following varicella infection with a good prognosis is reported. A somatosensory evoked magnetic field (SEF) study using a 37-channel-magnetoencephalography system demonstrated normal latency and strength of the first component (N20m) elicited by median nerve stimulation, despite bilateral symmetrical thalamic lesions on MRI. The normal SEF findings and the good prognosis suggested a reversible breakdown of the blood-brain barrier, and an edematous process as the brain pathology. Furthermore, our results support the idea of distinct generators for the three earliest cortical SEF components (N20m, P30m, N45m).

Chickenpox↗

PubMed2001

Genetic ablation of orexin neurons in mice results in narcolepsy, hypophagia, and obesity.

Orexins (hypocretins) are a pair of neuropeptides implicated in energy homeostasis and arousal. Recent reports suggest that loss of orexin-containing neurons occurs in human patients with narcolepsy. We generated transgenic mice in which orexin-containing neurons are ablated by orexinergic-specific expression of a truncated Machado-Joseph disease gene product (ataxin-3) with an expanded polyglutamine stretch. These mice showed a phenotype strikingly similar to human narcolepsy, including behavioral arrests, premature entry into rapid eye movement (REM) sleep, poorly consolidated sleep patterns, and a late-onset obesity, despite eating less than nontransgenic littermates. These results provide evidence that orexin-containing neurons play important roles in regulating vigilance states and energy homeostasis. Orexin/ataxin-3 mice provide a valuable model for studying the pathophysiology and treatment of narcolepsy.

Animals↗

PubMed2001

DNA methylation is a critical cell-intrinsic determinant of astrocyte differentiation in the fetal brain.

Astrocyte differentiation, which occurs late in brain development, is largely dependent on the activation of a transcription factor, STAT3. We show that astrocytes, as judged by glial fibrillary acidic protein (GFAP) expression, never emerge from neuroepithelial cells on embryonic day (E) 11.5 even when STAT3 is activated, in contrast to E14.5 neuroepithelial cells. A CpG dinucleotide within a STAT3 binding element in the GFAP promoter is highly methylated in E11.5 neuroepithelial cells, but is demethylated in cells responsive to the STAT3 activation signal to express GFAP. This CpG methylation leads to inaccessibility of STAT3 to the binding element. We suggest that methylation of a cell type-specific gene promoter is a pivotal event in regulating lineage specification in the developing brain.

Animals↗

PubMed2001

Inhibition of BMP2-induced, TAK1 kinase-mediated neurite outgrowth by Smad6 and Smad7.

BACKGROUND: BMP2 is known to play a wide variety of roles, including some in the development of the nervous system. This cytokine has been reported to induce neurite outgrowth in rat pheochromocytoma PC12 cells via the activation of a p38 MAP kinase, although its regulatory mechanism remains largely to be elucidated. RESULTS: BMP2-induced neurite outgrowth in PC12 cells was inhibited by the introduction of a kinase-negative form of a MAP kinase kinase kinase, TAK1, an upstream regulatory kinase for p38 kinase. Following BMP2 stimulation, the expression of Smad6 and Smad7, inhibitory Smad species that are known to inhibit the BMP2-restricted Smad species, Smad1, Smad5 and Smad8, was up-regulated. Unexpectedly, over-expression of either Smad6 or Smad7 in PC12 cells repressed the BMP2-induced neurite outgrowth and severely impeded the p38 kinase pathway. Both of these inhibitory Smads were found to interact physically with TAK1-binding protein, a molecule required for TAK1 activation. CONCLUSIONS: This study demonstrates that BMP2-induced neurite outgrowth in PC12 cells involves activation of the TAK1-p38 kinase pathway which is inhibited by Smad6 and Smad7.

Animals↗

PubMed2001

To eat or to sleep? Orexin in the regulation of feeding and wakefulness.

Orexin-A and orexin-B are neuropeptides originally identified as endogenous ligands for two orphan G-protein-coupled receptors. Orexin neuropeptides (also known as hypocretins) are produced by a small group of neurons in the lateral hypothalamic and perifornical areas, a region classically implicated in the control of mammalian feeding behavior. Orexin neurons project throughout the central nervous system (CNS) to nuclei known to be important in the control of feeding, sleep-wakefulness, neuroendocrine homeostasis, and autonomic regulation. orexin mRNA expression is upregulated by fasting and insulin-induced hypoglycemia. C-fos expression in orexin neurons, an indicator of neuronal activation, is positively correlated with wakefulness and negatively correlated with rapid eye movement (REM) and non-REM sleep states. Intracerebroventricular administration of orexins has been shown to significantly increase food consumption, wakefulness, and locomotor activity in rodent models. Conversely, an orexin receptor antagonist inhibits food consumption. Targeted disruption of the orexin gene in mice produces a syndrome remarkably similar to human and canine narcolepsy, a sleep disorder characterized by excessive daytime sleepiness, cataplexy, and other pathological manifestations of the intrusion of REM sleep-related features into wakefulness. Furthermore, orexin knockout mice are hypophagic compared with weight and age-matched littermates, suggesting a role in modulating energy metabolism. These findings suggest that the orexin neuropeptide system plays a significant role in feeding and sleep-wakefulness regulation, possibly by coordinating the complex behavioral and physiologic responses of these complementary homeostatic functions.

Animals↗

PubMed2001

Endothelin system: the double-edged sword in health and disease.

The endothelin system consists of two G-protein-coupled receptors, three peptide ligands, and two activating peptidases. Its pharmacological complexity is reflected by the diverse expression pattern of endothelin system components, which have a variety of physiological and pathophysiological roles. In the vessels, the endothelin system has a basal vasoconstricting role and participates in the development of diseases such as hypertension, atherosclerosis, and vasospasm after subarachnoid hemorrhage. In the heart, the endothelin system affects inotropy and chronotropy, and it mediates cardiac hypertrophy and remodeling in congestive heart failure. In the lungs, the endothelin system regulates the tone of airways and blood vessels, and it is involved in the development of pulmonary hypertension. In the kidney, it controls water and sodium excretion and acid-base balance, and it participates in acute and chronic renal failure. In the brain, the endothelin system modulates cardiorespiratory centers and the release of hormones. More advanced functional analysis of the endothelin system awaits not only additional pharmacological studies using highly specific endothelin antagonists but also the generation of genetically altered rodent models with conditional loss-of-function and gain-of-function manipulations.

Animals↗

PubMed2001

Endothelin B receptor deficiency potentiates ET-1 and hypoxic pulmonary vasoconstriction.

Endothelin (ET)-1 contributes to the regulation of pulmonary vascular tone by stimulation of the ET(A) and ET(B) receptors. Although activation of the ET(A) receptor causes vasoconstriction, stimulation of the ET(B) receptors can elicit either vasodilation or vasoconstriction. To examine the physiological role of the ET(B) receptor in the pulmonary circulation, we studied a genetic rat model of ET(B) receptor deficiency [transgenic(sl/sl)]. We hypothesized that deficiency of the ET(B) receptor would predispose the transgenic(sl/sl) rat lung circulation to enhanced pulmonary vasoconstriction. We found that the lungs of transgenic(sl/sl) rats are ET(B) deficient because they lack ET(B) mRNA in the pulmonary vasculature, have minimal ET(B) receptors as determined with an ET-1 radioligand binding assay, and lack ET-1-mediated pulmonary vasodilation. The transgenic(sl/sl) rats have higher basal pulmonary arterial pressure and vasopressor responses to brief hypoxia or ET-1 infusion. Plasma ET-1 levels are elevated and endothelial nitric oxide synthase protein content and nitric oxide production are diminished in the transgenic(sl/sl) rat lung. These findings suggest that the ET(B) receptor plays a major physiological role in modulating resting pulmonary vascular tone and reactivity to acute hypoxia. We speculate that impaired ET(B) receptor activity can contribute to the pathogenesis of pulmonary hypertension.

Animals↗

PubMed2001

ET(B) receptor activation causes exocytic insertion of NHE3 in OKP cells.

Endothelin-1 (ET-1) activates sodium/hydrogen exchanger 3 (NHE3) in opossum kidney clone P (OKP) cells expressing ET(B) receptors. ET-1 (10(-8) M) caused a two- to threefold increase in apical membrane NHE3 (assessed by surface biotinylation), in the absence of a change in total cellular NHE3. A maximal effect was achieved within 15 min. The increase in apical NHE3 was not blocked by cytochalasin D but was blocked by latrunculin B, which also prevented the ET-1-induced increase in NHE3 activity. Endocytic internalization of NHE3, measured as protection of biotinylated NHE3 from the membrane-impermeant, sulfhydryl-reducing agent MesNa was minimal within 35 min and was not regulated by ET-1. Exocytic insertion of NHE3, measured as the appearance of biotinylated NHE3 after the blockade of reactive sites with sulfo-NHS-acetate, was increased in response to ET-1. These studies demonstrate that ET-1 induces net trafficking of NHE3 to the apical membrane that is mediated by enhanced exocytic insertion and is required for increased NHE3 activity.

Alkaline Phosphatase↗

PubMed2001

Endothelin-1/endothelin-B receptor-mediated increases in NHE3 activity in chronic metabolic acidosis.

Decreases in blood pH activate NHE3, the proximal tubular apical membrane Na/H antiporter. In cultured renal epithelial cells, activation of the endothelin-B (ET(B)) receptor increases NHE3 activity. To examine the role of the ET(B) receptor in the response to acidosis in vivo, the present studies examined ET(B) receptor-deficient mice, rescued from neonatal lethality by expression of a dopamine beta-hydroxylase promoter/ET(B) receptor transgene (Tg/Tg:ET(B)(-/-) mice). In proximal tubule suspensions from Tg/Tg:ET(B)(+/-) mice, 10(-8) M endothelin-1 (ET-1) increased NHE3 activity, but this treatment had no effect on tubules from Tg/Tg:ET(B)(-/-) mice. Acid ingestion for 7 days caused a greater decrease in blood HCO(3)(-) concentration in Tg/Tg:ET(B)(-/-) mice compared with Tg/Tg:ET(B)(+/+) and Tg/Tg:ET(B)(+/-) mice. Whereas acid ingestion increased apical membrane NHE3 by 42-46% in Tg/Tg:ET(B)(+/+) and Tg/Tg:ET(B)(+/-) mice, it had no effect on NHE3 in Tg/Tg:ET(B)(-/-) mice. In C57BL/6 mice, excess acid ingestion increased renal cortical preproET-1 mRNA expression 2.4-fold and decreased preproET-3 mRNA expression by 37%. On a control diet, Tg/Tg:ET(B)(-/-) mice had low rates of ammonium excretion, which could not be attributed to an inability to acidify the urine, as well as hypercitraturia, with increased titratable acid excretion. Acid ingestion increased ammonium excretion, citrate absorption, and titratable acid excretion to the same levels in Tg/Tg:ET(B)(-/-) and Tg/Tg:ET(B)(+/+) mice. In conclusion, metabolic acidosis increases ET-1 expression, which increases NHE3 activity via the ET(B) receptor.

Acidosis↗

PubMed2001

Endothelium-specific loss of murine thrombomodulin disrupts the protein C anticoagulant pathway and causes juvenile-onset thrombosis.

The thrombomodulin (TM) gene was ablated in mice in a cell type-restricted manner from vascular endothelium by Cre-recombinase-mediated excision controlled by the endothelial cell lineage-specific Tie2 promoter. Forty percent of mutant (TMLox-) mice display a distinct lethal embryonic phenotype not observed in completely TM-deficient embryos. The remaining 60% of TMLox mice survive beyond birth, but invariably succumb to a severe hypercoagulable state and massive thrombosis after 3 weeks, terminating in a lethal consumptive coagulopathy. The progression of thrombosis was age- and sex-dependent. Disruption of the TM/protein C pathway was not associated with a latent proinflammatory state. Disease onset and progression could be prevented by warfarin anticoagulation. These results show that in mice, loss of endothelial cell TM function causes spontaneous and fatal thrombosis in the arterial and venous circulation, resulting from unfettered activation of the coagulation system. The combination of complete disease penetrance, uniform disease onset at young age, large vessel thrombosis of the extremities and multiple organ systems, and consumptive coagulopathy as the disease end-point provides a unique mouse model of human thrombotic disease.

Age Factors↗

PubMed2001

Impaired ventilatory responses to hypoxia in mice deficient in endothelin-converting-enzyme-1.

Endothelin-converting-enzyme (ECE-1) catalyzes the proteolytic activation of big endothelin-1 to mature endothelin-1. Most homozygous ECE-1-/- embryos die in utero and show severe craniofacial, enteric, and cardiac malformations precluding ventilatory function assessment. In contrast, heterozygous ECE-1+/- embryos develop normally. Their respiratory function at birth has not been studied. Taking into account previous respiratory investigations in mice with endothelin-1 gene disruption, we hypothesized that ECE-1-deficient mice may have impaired ventilatory control. We analyzed ventilatory responses to hypercapnia (8% CO(2)) and hypoxia (10% O(2)) in newborn and adult mice heterozygous for ECE-1 deficiency (ECE-1+/-) and in their wild-type littermates (ECE-1+/+). Ventilation, breath duration, and tidal volume were measured using whole-body plethysmography. Ventilatory responses to hypoxia were significantly weaker in ECE-1+/- than in ECE-1+/+ newborn mice (percentage ventilation increase: 1 +/- 25% versus 33 +/- 29%, p = 0.010). Baseline breathing variables and ventilatory responses to hypercapnia were normal in the ECE-1+/- newborn mice. No differences were observed between adult ECE-1+/- and ECE-1+/+ mice. We conclude that ECE-1 is required for normal ventilatory response to hypoxia at birth.

Animals↗

PubMed2001

Distinct cellular localization and regulation of endothelin-1 and endothelin-converting enzyme-1 expression in the bovine corpus luteum: implications for luteolysis.

Endothelin-1 (ET)-1 within the corpus luteum (CL) is rapidly up-regulated during natural or PGF(2 alpha)-induced luteolysis; however, such an increase was not observed at early luteal stage, when the CL is refractory to PGF(2 alpha). The mature and active form of ET-1 is derived from the inactive intermediate peptide, big ET-1, by ET-converting enzyme (ECE)-1. This study therefore examined the developmental and cell-specific expression of ECE-1 in bovine CL. A significant, 4-fold, elevation in ECE-1 expression (mRNA and protein levels) occurred during the transition of the CL from early to midluteal phase. Analysis using in-situ hybridization and enriched luteal cell subpopulations showed that both steroidogenic and endothelial cells of the CL expressed high levels of ECE-1 mRNA; prepro ET-1 mRNA, on the other hand, was only expressed by resident endothelial cells. These data suggest that luteal parenchymal and endothelial cells may cooperate in the biosynthesis of mature bioactive ET-1. In the mature CL, ECE-1 mRNA increase occurred both in steroidogenic and endothelial cells and was accompanied by a significant rise in ET-1 peptide. However, in contrast to ECE-1, prepro ET-1 mRNA levels were similar in early and midluteal-phase CL. Low ECE-1 levels during the early luteal phase, restricting the production of active ET-1, may explain why the immature CL is able to withstand PGF(2 alpha)-induced luteolysis.

Animals↗

PubMed2001

A reciprocal regulation of Ca(2+)-activated K(+) channel by insulin and somatostatin in guinea-pig pancreatic acinar cells.

The effects of islet hormones, insulin and somatostatin, on the regulation of the opening of Ca(2+)-activated K(+) channels in the basolateral plasma membrane of primary cultured pancreatic acinar cells of guinea-pig were studied by cell-attached single-channel recording technique. A single application of insulin or somatostatin did not influence the opening of K(+) channel. The open-state probability (p) of K(+) channel induced by the application of acetylcholine (ACh) to the bath solution was increased by insulin in the presence of ACh. The enhancement effect of insulin on the increased frequency of the channel opening was not seen when concomitantly applied with protein kinase A inhibitor, Rp-cAMPS triethylamine. Insulin increased the p value of K(+) channel, which was reversed by an application of somatostatin (Tyr-somatostatin 28). The addition of ACh followed by forskolin or dibutyryl adenosine 3',5'-cyclic monophosphate (dbcAMP) to the bath solution evoked an increase in the p value of K(+) channel. After increasing the channel opening, the addition of somatostatin reduced the p value, but not with dbcAMP. Taken together, the results suggest that insulin and somatostatin reciprocally modify the ACh-induced opening of the Ca(2+)-activated K(+) channel through a cyclic AMP-dependent signaling pathway.

Acetylcholine↗