Search PubMed⌕ Search

Biomedical subjects

Etsuro Ito

Publications and source records attributed to Etsuro Ito.

At least 19 recordsLinked to original sources
PubMed2026

Polycomb repressive complex 2 insufficiency underlies myeloid leukemia in Down syndrome.

Children with Down syndrome (DS) have an elevated risk of developing myeloid leukemia (ML; ML in DS [ML-DS]). In addition to mutations in GATA1, which generate the truncated isoform GATA1-short (GATA1s), ML-DS requires additional somatic gene mutations, most frequently in cohesion and Polycomb repressive complex 2 (PRC2) genes. Here, we show that PRC2 insufficiency underlies ML-DS pathogenesis. Transplantation of Gata1s fetal liver cells followed by deletion of the cohesion subunit Stag2 and/or the PRC2 component Ezh2 induced megakaryocyte-biased differentiation and expansion of megakaryocytic progenitors, culminating in lethal myelofibrosis. Mechanistically, loss of Stag2 or Ezh2 reinforced Gata1s-driven reduced chromatin accessibility at erythroid transcription factor target loci in premegakaryocyte/erythroid progenitors (pre-MegEs), thereby promoting megakaryocytic skewing. Ezh2 loss attenuated the Gata1s-mediated global elevation of H3K27 trimethylation in pre-MegEs, resulting in derepression of a broad set of PRC2 target genes and establishing a functionally PRC2-insufficient state. Similarly, Stag2 loss induced a moderate but significant degree of PRC2-insufficient state in Gata1s progenitors. Furthermore, chromosome 21-encoded miR-125b blocked megakaryocytic differentiation of Gata1s progenitors lacking either Stag2 or Ezh2 alone but drove full transformation and expansion of CD150+Sca-1+c-Kit+ leukemic stem cell-like populations only upon concurrent loss of both Stag2 and Ezh2, leading to acute megakaryoblastic leukemia in mice. These findings reveal that cohesin and PRC2 insufficiencies converge on PRC2 dysfunction while exerting distinct epigenetic effects and synergize with trisomy 21 and GATA1s to remodel the epigenetic landscape, driving progression from a preleukemic state to overt leukemia.

Animals↗
PubMed2006

Hsc70 ATPase: an insight into water dissociation and joint catalytic role of K+ and Mg2+ metal cations in the hydrolysis reaction.

Hybrid quantum mechanics/molecular mechanics simulations, coupled to the recently introduced metadynamics method, performed on the adenosine triphosphate (ATP) of the bovine Hsc70 ATPase protein, show which specific water molecule of the solvation shell of the Mg2+ metal cation acts as a trigger in the initial phase of the ATP hydrolysis reaction in ATP synthase. Furthermore, we provide a detailed picture of the reaction mechanism, not accessible to experimental probes, that allows us to address two important issues not yet unraveled: (i) the pathway followed by a proton and a hydroxyl anion, produced upon dissociation of a putative catalytic H2O molecule, that is crucial in the selection of the reaction channel leading to the hydrolysis; (ii) the unique and cooperative role of K+ and Mg2+ metal ions in the reaction, acting as co-catalysts and promoting the release of the inorganic phosphate via an exchange of the OH- hydroxyl anion between their respective solvation shells. This is deeply different from the proton wire mechanism evidenced, for instance, in actin and lowers significantly the free energy barrier of the reaction.

Adenosine Triphosphatases↗
PubMed2006

Treatment of difficult cases of systemic-onset juvenile idiopathic arthritis with tacrolimus.

Since a proportion of systemic-onset juvenile idiopathic arthritis (SOJIA) patients continue to require long-term corticosteroid therapy for disease control, an effective and safe therapeutic strategy for controlling the activity of refractory SOJIA remains to be established. We report the efficacy of tacrolimus for the treatment of SOJIA in two patients with refractory SOJIA, one of them showing poor response to cyclosporine A. Tacrolimus might be the treatment of choice in selected patients with refractory systemic-onset juvenile idiopathic arthritis. Further studies to confirm the long-term efficacy and safety of tacrolimus in larger numbers of patients are, however, needed.

Arthritis, Juvenile↗
PubMed2006

Periventricular efferent neurons in the optic tectum of rainbow trout.

The efferent connections and axonal and dendritic morphologies of periventricular neurons were examined in the optic tectum of rainbow trout to classify periventricular efferent neurons in salmonids. Among the target nuclei of tectal efferents, tracer injections to the following four structures labeled periventricular neurons: the area pretectalis pars dorsalis (APd), nucleus pretectalis superficialis pars magnocellularis (PSm), nucleus ventrolateralis of torus semicircularis (TS), and nucleus isthmi (NI). Two types of periventricular neurons were labeled by injections to the APd. One of them had an apical dendrite ramifying at the stratum fibrosum et griseum superficiale (SFGS), with an axon that bifurcated into two branches at the stratum griseum centrale (SGC), and the other had an apical dendrite ramifying at the SGC. Two types of periventricular neurons were labeled after injections to the TS. One of them had an apical dendrite ramifying at the boundary between the stratum opticum (SO) and the SFGS, and the other had dendritic branches restricted to the stratum album centrale or stratum periventriculare. Injections to the PSm and NI labeled periventricular neurons of the same type with an apical dendrite ramifying at the SO and a characteristic axon that split into superficial and deep branches projecting to the PSm and NI, respectively. This cell type also possessed axonal branches that terminated within the tectum. These results indicate that periventricular efferent neurons can be classified into at least five types that possess type-specific axonal and dendritic morphologies. We also describe other tectal neurons labeled by the present injections.

Animals↗
PubMed2006

Altered gene activity correlated with long-term memory formation of conditioned taste aversion in Lymnaea.

The pond snail Lymnaea stagnalis is capable of learning conditioned taste aversion (CTA) and then consolidating that learning into long-term memory (LTM) that persists for at least 1 month. LTM requires de novo protein synthesis and altered gene activity. Changes in gene activity in Lymnaea that are correlated with, much less causative, memory formation have not yet been identified. As a first step toward rectifying this situation, we constructed a cDNA microarray with mRNAs extracted from the central nervous system (CNS) of Lymnaea. We then, using this microarray assay, identified genes whose activity either increased or decreased following CTA memory consolidation. We also identified genes whose expression levels were altered after inhibition of the cyclic AMP response element-binding protein (CREB) that is hypothesized to be a key transcription factor for CTA memory. We found that the molluscan insulin-related peptide II (MIP II) was up-regulated during CTA-LTM, whereas the gene encoding pedal peptide preprohormone (Pep) was down-regulated by CREB2 RNA interference. We next examined mRNAs of MIP II and Pep using real-time RT-PCR with SYBR Green. The MIP II mRNA level in the CNS of snails exhibiting "good" memory for CTA was confirmed to be significantly higher than that from the CNS of snails exhibiting "poor" memory. In contrast, there was no significant difference in expression levels of the Pep mRNA between "good" and "poor" performers. These data suggest that in Lymnaea MIP II may play a role in the consolidation process that forms LTM following CTA training.

Analysis of Variance↗
PubMed2006

Identification and expression analysis of rainbow trout pumilio-1 and pumilio-2.

Pumilio is a sequence-specific RNA-binding protein that regulates translation from the relevant mRNA. The PUF-domain, the RNA-binding motif of Pumilio, is highly conserved across species. In the present study, we have identified two pumilio genes (pumilio-1 and pumilio-2) in rainbow trout and analyzed their expression patterns in its tissues. Pumilio-1 mRNA and pumilio-2A mRNA code for typical full length Pumilio proteins that contain a PUF-domain, whereas pumilio-2B mRNA is a splice variant of pumilio-2 and encodes a protein that lacks the PUF-domain. We have also identified a novel 72-bp exon that has not been reported in other animal species but is conserved in fish species. The insertion of this novel exon leads to the expression of an isoform of the Pumilio-2 protein with a slightly altered conformation of the PUF-domain. Pumilio-1 mRNA and pumilio-2A mRNA (irrespective of the presence of the 72-bp exon) are expressed in both the brain and ovaries at high levels, whereas pumilio-2B mRNA is expressed at low levels in all the rainbow trout tissues examined. Western blot analysis also indicates that the full length Pumilio proteins are expressed predominantly in the brain and ovaries. These data suggest that the Pumilio proteins have physiological roles and are involved in regulatory mechanisms in rainbow trout.

Alternative Splicing↗
PubMed2006

Comprehensive genetic analysis of relevant four genes in 49 patients with Marfan syndrome or Marfan-related phenotypes.

In order to evaluate the contribution of FBN1, FBN2, TGFBR1, and TGFBR2 mutations to the Marfan syndrome (MFS) phenotype, the four genes were analyzed by direct sequencing in 49 patients with MFS or suspected MFS as a cohort study. A total of 27 FBN1 mutations (22 novel) in 27 patients (55%, 27/49), 1 novel TGFBR1 mutation in 1 (2%, 1/49), and 2 recurrent TGFBR2 mutations in 2 (4%, 2/49) were identified. No FBN2 mutation was found. Three patients with either TGFBR1 or TGFBR2 abnormality did not fulfill the Ghent criteria, but expressed some overlapping features of MFS and Loeys-Dietz syndrome (LDS). In the remaining 19 patients, either of the genes did not show any abnormalities. This study indicated that FBN1 mutations were predominant in MFS but TGFBRs defects may account for approximately 5-10% of patients with the syndrome.

Activin Receptors, Type I↗
PubMed2006

Roles of periventricular neurons in retinotectal transmission in the optic tectum.

The midbrain roof is a retinorecipient region referred to as the optic tectum in lower vertebrates, and the superior colliculus in mammals. The retinal fibers projecting to the tectum transmit visual information to tectal retinorecipient neurons. Periventricular neurons are a subtype of these neurons that have their somata in the deepest layer of the teleostean tectum and apical dendrites ramifying at more superficial layers consisting of retinal fibers. The retinotectal synapses between the retinal fibers and periventricular neurons are glutamatergic, and ionotropic glutamate receptors mediate the transmission in these synapses. This transmission involves long-term potentiation, and is modulated by hormone action. Visual information processed in the periventricular neurons is transmitted to adjacent tectal cells and target nuclei of periventricular neuron axonal branches, some of which relay the visual information to other brain areas controlling behavior. We demonstrated that periventricular neurons play a principal role in visual information processing in the teleostean optic tectum; the effects of tectal output on behavior is discussed also in the present review.

Animals↗
PubMed2006

Glutamate release from astrocytes is stimulated via the appearance of exocytosis during cyclic AMP-induced morphologic changes.

Recent studies have shown that astrocytes release various transmitters including glutamate and thus directly affect synaptic neurotransmission. The mechanisms involved in the release of glutamate from astrocytes remain unclear, however. In the present study, we examined differences in 1) the amount of glutamate released, 2) the appearance of exocytosis, and 3) the expression of SNARE (soluble N-ethylmaleimide sensitive fusion protein attachment protein receptor) proteins between cyclic AMP-treated and non-treated astrocytes in culture. Extracellular glutamate was detected in the recording solution of cyclic AMP-treated astrocytes after stimulation with ATP by high-performance liquid chromatography and NADH imaging. Exocytosis, which was observed by FM1-43 imaging, appeared in cyclic AMP-treated astrocytes in a punctiform fashion, but not in non-treated cells, after stimulation with ATP and glutamate. Immunocytochemistry and Western blotting showed that the amount of SNARE proteins increased during cAMP-induced morphologic changes, and in particular, a v-SNARE, synaptobrevin, appeared as punctiform staining in the cytosol of cyclic AMP-treated astrocytes. These findings show that astrocytes acquire SNARE proteins during cyclic AMP-induced differentiation, and suggest that glutamate is released by exocytosis in cyclic AMP-treated astrocytes in response to ATP released from neighboring neurons and astrocytes.

Animals↗
PubMed2006

Long-term mizoribine intermittent pulse therapy for young patients with flare of lupus nephritis.

Mizoribine (MZR) is a novel purine synthesis inhibitor that was developed in Japan. We previously reported the efficacy and safety of oral MZR intermittent pulse therapy, which is associated with elevated peak serum MZR levels, in selected patients with lupus nephritis. However, the efficacy and safety of long-term MZR intermittent pulse therapy (administered for over 24 months) in lupus nephritis patients at high risk for relapse has not yet been reported. Our study included five patients with a long history of systemic lupus erythematosus (SLE), including four patients with proliferative lupus nephritis (WHO class IV) and one patient with WHO class II lupus nephritis, in whom remission had been achieved through treatment with high-dose corticosteroids combined with cytotoxic agents. For the most recent flares, all the patients were treated with MZR intermittent pulse therapy without increase in the dose of corticosteroids. MZR was administered at 5-10 mg/kg per day (up to 500 mg) as a single daily dose on two days of the week (Monday and Thursday) for over 24 months. Concomitantly administered corticosteroid dose was gradually reduced or continued unchanged. At presentation, the urinary protein excretion, serum complement hemolytic activity (CH50) and serum anti-dsDNA antibody titer were 1.7+/-1.0 g/day, 16.6+/-3.8 U/mL (normal, 23-46 U/mL) and 143.7+/-151.1 IU/mL (normal,<12.0 IU/mL), respectively. At the latest observation point, after a mean interval of 31 months (24-34 months) after the initiation of MZR pulse therapy, the urinary protein excretion and serum anti-dsDNA antibody titer were significantly decreased (0.3+/-0.2 g/day and 18.5+/-19.1 IU/mL, respectively; P<0.05), and the serum CH50 value had returned to within normal range (33.6+/-7.8 U/mL, P<0.05). Despite the reduced minimum dose of prednisolone required to maintain clinical remission at the time of the post-treatment evaluation after MZR pulse therapy as compared with that at the time of the pretreatment evaluation (9.0+/-4.5 vs. 17.5+/-7.9 mg/day; P=0.0656), the calculated flare rate was significantly decreased (0.15+/-0.2 vs. 0.6+/-0.11 times per year; P<0.05). The serum creatinine level remained within normal range in all the study participants. Furthermore, the platelet count increased following the MZR pulse therapy in two patients who had suffered from chronic thrombocytopenia. No serious adverse effects were observed. From the view point of the balance between suppression of disease activity and the adverse effects of treatment, we believe that long-term MZR pulse therapy may be the treatment of choice in selected patients with lupus nephritis at high risk for relapse. However, this was only a pilot study conducted on a small number of subjects, without a control group. Further studies to confirm the long-term efficacy and safety of oral MZR intermittent pulse therapy in larger numbers of patients are needed.

Adolescent↗
PubMed2006

Leukocytapheresis for the treatment of refractory systemic-onset juvenile idiopathic arthritis.

Although leukocytapheresis (LCAP) has been reported to be effective for the treatment of various autoimmune disorders, little information has been published yet on the efficacy and safety of LCAP for the treatment of systemic-onset juvenile idiopathic arthritis (SOJIA). A pilot trial of LCAP was therefore conducted on two children with refractory SOJIA using a granulocyte apheresis filter packed with cellulose acetate beads in an attempt to control the disease flares. Following three to eight sessions of LCAP, the joint symptoms gradually resolved without any increase in the dose of corticosteroids. The procedure was associated with a decrease in the serum interleukin-6. No severe adverse effects were observed except for mild nausea. However, efficacy of LCAP sustained in a short time since both patients subsequently developed flares after 3 months of the treatment.

Adolescent↗
PubMed2006

De Novo synthesis of CREB in a presynaptic neuron is required for synaptic enhancement involved in memory consolidation.

Interaction between the activator type of cyclic AMP response element binding protein (CREB1) and the repressor type (CREB2) results in determining the emergence of long-lasting synaptic enhancement involved in memory consolidation. However, we still do not know whether the constitutively expressed forms of CREB are enough or the newly synthesized forms are required for the synaptic enhancement. In addition, if the newly synthesized forms are needed, we must determine the time for translation of CREB from its mRNA. We applied the methods of RNA interference and real-time polymerase chain reaction (PCR) to CREB in the cerebral giant cells of Lymnaea. The cerebral giant cells play an important role in associative learning and employ a CREB cascade for the synaptic enhancement to neurons such as the B1 motoneurons. We injected the small interfering RNA (siRNA) of CREB1 or CREB2 into the cerebral giant cells and examined the changes in amplitude of excitatory postsynaptic potential (EPSP) recorded in the B1 motoneurons. The changes in the amounts of CREB1 and CREB2 mRNAs were also examined in the cerebral giant cells. The EPSP amplitude was suppressed 15 min after injection of CREB1 siRNA, whereas that was augmented 60 min after injection of CREB2 siRNA. In the latter case, the decrease in the amount of CREB2 mRNA was confirmed by real-time PCR. Our results showed that the de novo synthesized forms of CREB are required within tens of minutes for the synaptic enhancement in memory consolidation.

Animals↗
PubMed2006

Development of acute megakaryoblastic leukemia from a minor clone in a Down syndrome patient with clinically overt transient myeloproliferative disorder.

A Down syndrome male showed leukocytosis from birth and was diagnosed as transient myeloproliferative disorder (TMD). Eight months later, his condition had progressed to myelodysplastic syndrome after spontaneous resolution, and it then evolved to acute megakaryoblastic leukemia (AMKL) at the age of 20 months. Sequencing analysis showed that the predominant TMD and AMKL clones had different GATA1 mutations, although a minor TMD clone identical to the AMKL clone was present at birth. These observations suggest that a minor clone rather than the predominant clone at the time of TMD may give rise to AMKL later on.

Cell Lineage↗
PubMed2006

Taste discrimination in conditioned taste aversion of the pond snail Lymnaea stagnalis.

Conditioned taste aversion (CTA) in the pond snail Lymnaea stagnalis has been widely used as a model for gaining an understanding of the molecular and behavioral mechanisms underlying learning and memory. At the behavioral level, however, it is still unclear how taste discrimination and CTA interact. We thus examined how CTA to one taste affected the feeding response induced by another appetitive food stimulus. We first demonstrated that snails have the capacity to recognize sucrose and carrot juice as distinct appetitive stimuli. We then found that snails can become conditioned (i.e. CTA) to avoid one of the stimuli and not the other. These results show that snails can distinguish between appetitive stimuli during CTA, suggesting that taste discrimination is processed upstream of the site where memory consolidation in the snail brain occurs. Moreover, we examined second-order conditioning with two appetitive stimuli and one aversive stimulus. Snails acquired second-order conditioning and were still able to distinguish between the different stimuli. Finally, we repeatedly presented the conditional stimulus alone to the conditioned snails, but this procedure did not extinguish the long-term memory of CTA in the snails. Taken together, our data suggest that CTA causes specific, irreversible and rigid changes from appetitive stimuli to aversive ones in the conditioning procedure.

Animals↗
PubMed2006

Cloning and characterization of the novel chimeric gene p53/FXR2 in the acute megakaryoblastic leukemia cell line CMK11-5.

The loss of p53 function is a key event in tumorigenesis. Inactivation of p53 in primary tumors and cell lines is mediated by several molecular mechanisms, including deletions and rearrangements. However, generation of a p53 fusion gene has not yet been reported. Here we report a novel p53/an autosomal homolog of the fragile X mental retardation (FXR2) chimeric gene generated by an interstitial deletion. Western blot analyses have shown that the p53/FXR2 protein is indeed expressed in a Down syndrome-related acute megakaryoblastic leukemia cell line, CMK11-5 cells. To investigate the properties of the p53/FXR2 protein, we observed its subcellular localization. Flag-tagged expression vectors were transfected into COS-7 cells and the proteins were stained with an anti-Flag antibody. The p53/FXR2 protein was expressed at high levels in the cytoplasm, whereas wild-type p53 and FXR2 were localized primarily in the nucleus and in the periphery of the nucleus, respectively. Treatment with a topoisomerase II inhibitor, VP16, failed to induce expression of a p53 target gene, the cyclin-dependent kinase inhibitor p21(WAF-1/CIP1), in CMK11-5 cells, and transient transfection analysis showed that the p53/FXR2 protein failed to transactivate the p21(WAF-1/CIP1) promoter. These results suggest that the p53/FXR2 fusion protein lacks the ability of wild-type p53 to function as a transcription factor. The p53/FXR2 gene is the first reported p53 fusion gene.

Animals↗
PubMed2006

Renal biopsy findings in children receiving long-term treatment with cyclosporine a given as a single daily dose.

Long-term treatment of childhood nephrotic syndrome (NS) and rheumatic diseases with cyclosporine A (CsA) given as a single daily dose may yield better results and allow safer use of the drug than the conventional twice-daily dosing. However, the safety of such long-term treatment from the histological standpoint remains to be established. Posttreatment renal biopsy was conducted in a total of eight children (5 with minimal change NS, 2 with focal segmental glomerulosclerosis and 1 with X-linked immune dysregulation, polyendocrinopathy and enteropathy) receiving CsA as a single daily dose, after a mean treatment duration of 20 months (9-36 months). The initial daily dose of CsA (Neoral) was 2.0 mg/kg, given as a single daily dose before breakfast. The dose was subsequently adjusted to achieve a peak (between 1 and 2 hrs post-dosing, C1-C2) blood level of around 800 ng/ml. The mean daily CsA dose, mean C1-C2 blood level, and mean trough blood level in the subjects were 1.9 +/- 0.6 mg/kg, 803.8 +/- 117.2 ng/ml and 36.1 +/- 12.7 ng/ml, respectively. The result revealed no evidence of CsA-related nephrotoxicity, including arteriopathy, striped interstitial fibrosis or tubular atrophy, in any of the study participants. Also, no significant changes were observed in the mean estimated glomerular filtration rate as compared to the pretreatment values (127.6 +/- 14.9 ml/min/1.73 m(2) vs 115.6 +/- 22.8 ml/min/1.73 m(2), and except for mild hypertrichosis, no significant adverse effects of CsA were observed. These findings lend further support to the safety of long-term low-dose CsA treatment (median treatment duration in this study, 20 months), with the drug administered as a single daily dose while maintaining a peak (C1-C2) blood level of around 800 ng/ml.

Adolescent↗
PubMed2005

Requirement of new protein synthesis of a transcription factor for memory consolidation: paradoxical changes in mRNA and protein levels of C/EBP.

Some specific transcription factors are essential for memory consolidation across species. However, it is still unclear whether only the activation of constitutively expressed forms of these conserved transcription factors is involved in memory consolidation or their de novo synthesis also occurs after learning. This question has remained unanswered partly because of the lack of an efficient method for the determination of copy numbers of particular mRNAs in single neurons, which allows the detection of new transcription at the cellular level. Here we applied a newly developed protocol of single-cell quantitative real-time polymerase chain reaction (qRT-PCR) to single neurons playing an important role in associative learning. Specifically, we examined the changes in the mRNA and protein expression levels of a highly conserved transcription factor, CCAAT/enhancer binding protein (C/EBP), in the paired B2 motoneurons of the pond snail Lymnaea stagnalis. These buccal neurons are involved in the motor control of feeding behavior, with a potentially important role in conditioned taste aversion (CTA). Single-cell qRT-PCR revealed a significant decrease in LymC/EBP mRNA copy numbers in the B2 motoneurons during memory consolidation after CTA training. By contrast, isoelectric focusing and immunoblotting of extracts of the buccal ganglia showed that translation and phosphorylation levels of LymC/EBP significantly increased during memory consolidation. The C/EBP-like immunoreactivity in the B2 motoneurons, which are the major immunopositive component in the buccal ganglia, also significantly increased during memory consolidation, suggesting that the main source of increase in the level of protein in the buccal ganglia are the B2 motoneurons. Thus, early memory consolidation after CTA learning in L.stagnalis involves both the rapid synthesis and phosphorylation of LymC/EBP as well as the rapid breakdown of LymC/EBP mRNA in the neural network controlling feeding, suggesting that all of these processes play a role in the function of C/EBP in memory consolidation.

Amino Acid Sequence↗