Biomedical subjects

T Furuyama

Publications and source records attributed to T Furuyama.

At least 37 records · Page 2Linked to original sources

PubMed1999

Mouse semaphorin H inhibits neurite outgrowth from sensory neurons.

Mouse semaphorin H (M-semaH) was structurally similar to semaphorin III/D, a mammalian homologue of collapsin 1 which was identified as a collapsing factor for sensory nerves. In this study we investigated the expression patterns of M-semaH mRNA and the protein binding sites in the trunk of mouse embryos. M-semaH mRNA was expressed in the mesenchymal tissues surrounding each dorsal root ganglia. These tissues include the caudal sclerotome and perinotochordal mesenchyme, which were thought to express factors repulsive to axons. M-semaH binding was detected on the spinal nerves. We further investigated, using in vitro co-culture assay, whether M-semaH acted as a chemorepulsive molecule on sensory axons. The results suggested that M-semaH was a candidate for a chemorepellent expressed in the mesenchyme surrounding the sensory ganglia, which is involved in the axonal guidance mechanism of sensory nerves in the trunk.

3T3 Cells↗

PubMed1999

Developmental localization of semaphorin H messenger RNA acting as a collapsing factor on sensory axons in the mouse brain.

Semaphorins/collapsins, a family of genes with a semaphorin domain conserved from insects through to mammals, are believed to be involved in axon guidance during neuronal development. We report the expression patterns of mouse semaphorin messenger RNAs. Among secreted semaphorins, mouse semaphorin H is structurally most similar to semaphorin III/D, the first semaphorin identified as a collapsing factor for sensory axons. However, its expression patterns apparently differ from those of semaphorin III/D. The messenger RNAs are distributed in the brain widely but unevenly during development, in particular, in the main olfactory bulb, hippocampus and pontine nucleus. In the trunk, the expression level is high in mesodermal tissues surrounding the dorsal root ganglia, while it is low in the spinal cord. Moreover, we examined whether this molecule has activity to collapse growth cones of sensory neurons, as well as semaphorin III/D. Mouse semaphorin H collapsed growth cones of sensory neurons of the dorsal root ganglion in a dose-dependent manner, and anti-neuropilin antibodies inhibited this activity. Taken together, these results suggest that mouse semaphorin H can function as a chemorepellent to guide sensory peripheral nerves, most likely via neuropilin as a receptor.

Amino Acid Sequence↗

PubMed1999

A novel calcium-binding protein is expressed in Brassica pistils and anthers late in flower development.

We describe the cloning and characterization of PCP, a novel calcium-binding protein that is expressed predominantly in the pistils and anthers of Brassica flowers late in flower development. A PCP cDNA - isolated from a subtracted cDNA library enriched in transcripts present in the pistil late in flower development - potentially encodes a 175 amino acid protein with a calculated molecular weight of 19.1 kDa. Other than limited homology to a repetitive C-terminal polyacidic region of PCP, none of the sequences in the GenBank database shares identity to PCP. This unique protein was purified from an Escherichia coli expression system and shown to bind calcium in a specific manner, both in a protein blot assay and by equilibrium dialysis. PCP binds 29 mol of calcium per mol of PCP protein with an apparent affinity constant of 3.2 x 10(2)/M, values consistent with the presence of a high capacity/low-affinity calcium-binding domain. PCP-specific mRNAs are detected predominantly in the stigma and style of pistils excised from open flowers; much lower levels of expression are seen in anthers of open flowers and in root and leaf tissue. Expression in the pistil steadily increases during flower development and peaks at flower opening. A PCP-specific antibody first detects the protein in pistils at one day prior to flowering, with higher levels of the protein seen in the pistils of open flowers. A low level of the protein is present in anthers of open flowers; however, PCP is not detected in either root or leaf extracts. The pattern of PCP expression is consistent with a possible role for PCP in pollen-pistil interactions or in pistil development. The results are also discussed in light of the central role calcium maintains in pollen tube growth and fertilization.

Amino Acid Sequence↗

PubMed1999

A novel presenilin-2 splice variant in human Alzheimer's disease brain tissue.

Mutations in the presenilin-1 (PS-1) and presenilin-2 (PS-2) genes account for the majority of cases of early-onset familial Alzheimer's disease (AD). Alternative splicing forms of the PS-1 and PS-2 gene products have previously been reported in fibroblast and brain tissue from both familial and sporadic AD patients, as well as from normal tissues and cell lines. We demonstrate here unusual alternative splicing of the PS-2 gene that leads to the generation of mRNA lacking exon 5 in human brain tissue. This product was more frequently detected in brain tissue from sporadic AD patients (70.0%; 21 of 30) than from normal age-matched controls (17.6%; three of 17). In cultured neuroblastoma cells, this splice variant was generated in hypoxia but not under other forms of cellular stress. Hypoxia-mediated induction of this splice variant was blocked by pretreatment of neuroblastoma cells with the protein synthesis inhibitor cycloheximide or antioxidants such as N-acetylcysteine and diphenyl iodonium, suggesting that hypoxia-mediated oxidant stress might, at least in part, underlie the alternative splicing of PS-2 mRNA through de novo protein synthesis. Furthermore, the stable transfectants of this splice variant produced the N-terminal part of PS-2 protein (15 kDa) and were more susceptible to cellular stresses than control transfectants. These results suggest the possibility that altered presenilin gene products in stress conditions may also participate in the pathogenesis of AD.

Aged↗

PubMed1998

Expression of copper trafficking genes in the mouse brain.

Copper homeostasis in the brain must be strictly maintained, since copper is an essential trace element and is potentially toxic. To understand the mechanism of copper homeostasis in the brain, we cloned several mouse homologues of copper trafficking genes and performed in situ hybridization histochemistry. mCTR1, mATX1, and mATP7a were highly expressed in the choroid plexus, indicating that the choroid plexus uses the trafficking pathway from uptake to efflux to transport copper to the cerebrospinal fluids. We suggest that these genes may regulate copper concentration in the brain through the choroid plexus.

Adenosine Triphosphatases↗

PubMed1998

The Drosophila Polycomb Group proteins ESC and E(Z) bind directly to each other and co-localize at multiple chromosomal sites.

The Polycomb Group gene esc encodes an evolutionarily conserved protein required for transcriptional silencing of the homeotic genes. Unlike other Polycomb Group genes, esc is expressed and apparently required only during early embryogenesis, suggesting it is required for the initial establishment of silencing but not for its subsequent maintenance. We present evidence that the ESC protein interacts directly with E(Z), another Polycomb Group protein required for silencing of the homeotic genes. We show that the most highly conserved region of ESC, containing seven WD motifs that are predicted to fold into a beta-propeller structure, mediate its binding to a conserved N-terminal region of E(Z). Mutations in the WD region that perturb ESC silencing function in vivo also perturb binding to E(Z) in vitro. The entire WD region forms a trypsin-resistant structure, like known beta -propeller domains, and mutations that would affect the predicted ESC beta-propeller perturb its trypsin-resistance, while a putative structure-conserving mutation does not. We show by co-immunoprecipitation that ESC and E(Z) are directly associated in vivo and that they also co-localize at many chromosomal binding sites. Since E(Z) is required for binding of other Polycomb Group proteins to chromosomes, these results suggest that formation of an E(Z):ESC complex at Polycomb Response Elements may be an essential prerequisite for the establishment of silencing.

Amino Acid Sequence↗

PubMed1997

LIM-homeodomain gene family in neural development.

In the present study, we isolated five murine LIM-homeodomain (LH) genes including a novel gene designated as L3 which is expressed specifically in the medial ganglionic eminence of the embryonic brain and the mesenchyme surrounding the oral cavity. The comparison of the expression domains in the embryonic forebrain using in situ hybridization histochemistry proved that three LH genes (LH-2, lim-1, and L3) share sharp boundaries. In addition to the prosomeric boundaries in the diencephalon, this gene family defines novel boundaries in the basal telencephalon, the mesencephalon, and the rhombencephalon. These mutually exclusive expression domains suggest that this family might be involved in controlling the early compartmentalization and boundary formation of the developing central nervous system.

Animals↗

PubMed1997

[Prognostic implication of DNA contents on long-term outcome of childhood acute lymphoblastic leukemia].

Prognostic value of cellular DNA content was evaluated in 189 children with acute lymphoblastic leukemia. Treatment outcome of the three different DNA index (DI) groups (Group A, DI = 1.0 vs. Group B, DI 1.01-1.15 vs. Group C, DI > or = 1.16) was compared between the two treatment risk groups (standard-risk and high-risk groups) stratified by the initial leukocyte count and age. In the standard-risk group, these groups had 10-year event free survival (EFS) rate (SE) of 62% (6%), 40% (21%) and 87% (6%), respectively (p < 0.05). In the high risk group, they had 10-year EFS rate of 30% (5%), 33% (27%) and 60% (19%), respectively (p < 0.01). Use of the DI, leukocyte count and age may be sufficient to distinguish the patients with an extremely low risk of failing to the standard ALL therapy from the patients with a relatively high-risk of treatment failure.

Child↗

PubMed1996

Identification of a novel transmembrane semaphorin expressed on lymphocytes.

Semaphorin (also known as collapsin) members are thought to be involved in axon guidance during neural network formation. Here, we report the isolation of a novel member, mouse semaphorin G (M-sema G), which encodes a semaphorin domain followed by a single putative immunoglobulin-like domain, a transmembrane domain, and a cytoplasmic domain. M-sema G is most closely related to M-sema F, which we previously reported, and semB and semC. These four members appear to constitute a transmembrane type subfamily in mouse semaphorins. In contrast to the predominant expression of M-sema F mRNAs in the nervous tissues, M-sema G mRNAs are strongly expressed in lymphoid tissues, especially in the thymus, as well as in the nervous tissues. The mRNAs are also detected in various cell lines from hematopoietic cells. By generating specific antibodies, we confirmed the strong expression of M-Sema G proteins on the surface of lymphocytes. These results provide the first evidence that semaphorin is expressed on lymphocytes and suggest that semaphorins may play an important role in the immune system, as well as in the nervous system.

Amino Acid Sequence↗

PubMed1996

Differential expression of LIM-homeodomain genes in the embryonic murine brain.

Homeobox-containing genes are associated with the control of various stages in embryogenesis. LIM-homeodomain genes have been implicated in the control of differentiation of specific cell types in both neuronal and non-neuronal tissues, yet there have been few studies comparing the expression domains of these genes in the developing brain of a single species. In the present study, we isolated murine LIM-homeodomain genes (LH-2, lim-1, and L3) by reverse transcription-polymerase chain reaction (RT-PCR) method and investigated their expression domains in the embryonic brain by in situ hybridization analysis. These mRNAs showed mutually exclusive expression patterns suggesting that these factors may be involved in region-specific differentiation in the developing brain.

Amino Acid Sequence↗

PubMed1996

L3, a novel murine LIM-homeodomain transcription factor expressed in the ventral telencephalon and the mesenchyme surrounding the oral cavity.

By reverse-transcription polymerase chain reaction method, we isolated a novel murine LIM-homeodomain gene, L3. In situ hybridization analyses revealed that L3 mRNA was localized to the ventral telencephalon and the mesenchyme surrounding the oral cavity of mouse embryo, suggesting that L3 may be involved in the region-specific differentiation of these areas.

Amino Acid Sequence↗

PubMed1996

Localization of mRNAs for Rlim-1, the rat Xlim-1 homolog, in the developing rat brain.

We studied the localization of Rlim-1 mRNAs, the rat Xlim-1 homolog, in the developing rat brain using in situ hybridization histochemistry. On embryonic day 13 (E13), strong signals were observed in the most superficial layer of the telencephalon, the zonalimitans intrathalamica, the ventral thalamus, some nuclei of the hypothalamus, the tectum, the cerebellum, the lower brainstem and the spinal cord. In the above-mentioned regions except the cerebellum, the distribution pattern remained almost the same from embryonic stage to adulthood but the intensity of expression gradually decreased after birth. In the cerebellum, the distribution pattern changed. during development; all the primordium of cerebellum in E13, the external granular and the Purkinje cell layers in postnatal day 7 (P7), and only the Purkinje cell layer in the adult expressed positive signals. These results suggest that Rlim-1 may be involved in region specification.

Animals↗

PubMed1996

Differential distribution of mRNA encoding cAMP-specific phosphodiesterase isoforms in the rat brain.

We studied the distributions of four different cyclic AMP-specific phosphodiesterase isoform mRNAs (APDE1-4) and compared them with that of 63 kDa calmodulin-stimulated phosphodiesterase (CPDE) in the rat brain by in situ hybridization histochemistry using specific radiolabeled oligonucleotides. The distribution patterns were unique for all the APDE isoforms examined here. Although no significant signals for APDE1 could be detected anywhere in the rat brain, all other isoforms were expressed ubiquitously but unevenly and showed overlapping distribution patterns. Among all the APDE isoforms studied here, APDE3 showed the strongest and the most extensive expression. Its distribution pattern implies that it may modulate different cellular processes associated with learning and memory. Compared to APDE3, the levels of expression of APDE2 and APDE4 were weaker, the latter showing the weakest expression. Our study suggests that different isoforms of APDE are expressed together in the same class of neurons implying complex interactions among different signaling pathways, thereby mediating distinct and specific functions.

3',5'-Cyclic-AMP Phosphodiesterases↗

PubMed1995

Identification of a member of mouse semaphorin family.

Grasshopper semaphorin I (Sema I) and its related proteins, chick collapsin and mouse Sema III contribute to the axon guidance by their repellent actions [5,9,12]. We have identified a member of semaphorin gene family from the mouse brain and named it M-Sema F. The N-terminal encodes a semaphorin domain that is similar between Sema I-III [6] followed by a single putative immunoglobulin-like domain, a transmembrane domain, and a proline-rich intracellular domain. M-Sema F mRNA is expressed widely in the nervous tissues during development. These suggest that M-Sema F is a transmembrane member of the semaphorin family of the vertebrate which may function in the developing neuronal network.

Amino Acid Sequence↗

PubMed1994

Distribution of Rlim, an LIM homeodomain gene, in the rat brain.

We examined the distribution of Rlim, a homologue to Xlim-1, in the rat brain. Rlim, a LIM class homeodomain gene, was isolated from rat brain, and localized in the adult brain by in situ hybridization histochemistry. The expression of Rlim was found in discrete regions, such as the Purkinje cell layer of the cerebellum and several nuclei of the hypothalamus, midbrain and pons. This suggests that Rlim is related to regulation of genes that are specific to some neurons such as Purkinje cells in the adult.

Amino Acid Sequence↗

PubMed1994

Distinct regulation of sodium channel types I, II and III following nerve transection.

We investigated mRNA expression of type I, II and III voltage-sensitive sodium channels in motoneurons following facial nerve transection by means of in situ hybridization histochemistry. Type I mRNA expression decreased markedly after nerve transection, while that of type III increased. Type II expression underwent no detectable change following nerve transection. These results suggest that type III sodium channels may be involved in regeneration and plasticity.

Animals↗

PubMed1994

Localization of 63-kDa calmodulin-stimulated phosphodiesterase mRNA in the rat brain by in situ hybridization histochemistry.

We studied the localization of 63-kDa Ca2+/calmodulin stimulated phosphodiesterase mRNA in the rat brain by in situ hybridization histochemistry using an oligonucleotides probe specific to this enzyme. The signals were especially concentrated in several brain regions such as the olfactory tubercle, accumbens nucleus, caudate putamen, fundus striati, dentate gyrus of the hippocampus, pontine nuclei and dorsal tegmental nucleus. These results suggest that in the neuronal groups containing the strong signals this enzyme is involved in calcium-dependent signal transduction system coupled to cyclic nucleotides messenger systems.

Animals↗

PubMed1994

Potentiated 1,25(OH)2D3-induced 24-hydroxylase gene expression in uremic rat intestine.

24-Hydroxylase has been considered a major enzyme regulating metabolism of circulating 1 alpha, 25-dihydroxyvitamin D3 [1,25(OH)2D3]. To understand the metabolism of 1,25(OH)2D3 in chronic renal failure, we examined 1,25(OH)2D3-induced 25-hydroxyvitamin D3-24-hydroxylase (24-hydroxylase) gene expression in the intestine of uremic rats. Northern blot and dot blot analyses showed that the induction of duodenal 24-hydroxylase gene expression was 2.0- to 3.8-fold greater in uremic rats than in sham-operated rats (P < 0.05, Student's t-test) at 6 h after 1,25(OH)2D3 administration. Gene induction of calbindin D9k by 1,25(OH)2D3 was not augmented in uremic group. In situ hybridization analysis revealed that the induction of 24-hydroxylase mRNA by 1,25(OH)2D3 was observed exclusively in the columnar epithelium of the crypt and the lower part of the villi, suggesting that the stage of epithelial cell differentiation is a major determinant of 1,25(OH)2D3-induced 24-hydroxylase gene expression. In uremia, 1,25(OH)2D3-induced 24-hydroxylase gene expression was accelerated selectively, possibly because of poorly differentiated epithelial cells.

Animals↗