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M Fukaya

Publications and source records attributed to M Fukaya.

At least 19 recordsLinked to original sources

Identification and characterization of novel developmentally regulated neural-specific proteins, BRINP family.

Processes of neuronal differentiation involve activation of a set of neuronal specific genes and cessation of cell proliferation in postmitotic neurons. Previous studies revealed that bone morphogenetic protein (BMP) and retinoic acid (RA) play important roles in the differentiation of peripheral sympathetic neurons such as the synergistic induction of responsiveness to specific neurotrophic factors. In the present study, while trying to clarify the mechanism of the BMP/RA-actions, we identified a novel neural-specific protein, BMP/RA-inducible neural-specific protein-1 (BRINP1) which shows no similarity to other known proteins. Subsequently, two homologous proteins, BRINP2 and BRINP3, making up the BRINP family, are identified. Individual BRINP genes have distinct regulatory mechanisms of expression within the nervous system. In rodent brain, BRINP1 is expressed from earlier developmental stage, i.e. E9.5, and widely expressed in various neuronal layers and nuclei of the adult animal, while BRINP2 and BRINP3 were detectable from E11.5 and expressed in rather limited regions in a complementary manner. During the course of perinatal development of sympathetic neurons, BRINP1 is induced from earlier embryonic stage and further increased toward adult stage, while BRINP3 expressed from earlier stage is replaced by BRINP2 expression which increases postnatally in accordance with the action of BMP2 and RA. Furthermore, when expressed in nonneuronal cells, all three BRINP family proteins suppressed the cell cycle progression. Possible physiological functions of BRINP family members in the development of the nervous system are discussed.

Amino Acid Sequence↗

The efficacy of acetic acid for glycogen repletion in rat skeletal muscle after exercise.

We examined the effect of acetic acid, the main component of vinegar, on glycogen repletion by using swimming-exercised rats. Rats were trained for 7 days by swimming. After an overnight fast, they were subjected to a 2-hr swimming exercise. Immediately afterward, they were given by gavage 2 ml of one of the following solutions: 30 % glucose only or 30 % glucose with 0.4 % acetic acid. Rats were sacrificed by decapitation before, immediately after exercise and 2 hours after the feeding. Exercise significantly decreased soleus and gastrocnemius glycogen content, and feeding significantly increased liver, soleus and gastrocnemius glycogen content. In soleus muscle, acetate feeding significantly increased glycogen content and the ratio of glycogen synthase in the I form (means +/- SEM: 4.04 +/- 0.41 mg/g-tissue and 47.0 +/- 0.7 %, respectively) in contrast to no acetate feeding (3.04 +/- 0.29 mg/g-tissue and 38.1 +/- 3.4 %, respectively). Thus, these findings suggest that the feeding of glucose with acetic acid can more speedily accelerate glycogen repletion in skeletal muscle than can glucose only.

Acetic Acid↗

Differential palmitoylation of two mouse glutamate receptor interacting protein 1 forms with different N-terminal sequences.

Glutamate receptor interacting protein (GRIP) is a member of the PDZ domain-containing protein family that is localized in the postsynaptic density area. This protein has been reported to interact specifically with the C-termini of AMPA-selective glutamate receptor channel subunits, GluRalpha2 and GluRalpha3 through its PDZ domains. To clarify the physiological functions of GRIP, we cloned mouse GRIP1, and found that there are three sites for alternative splicing and two putative translational start codons by characterizing GRIP1 cDNA clones and reverse transcription-polymerase chain reaction products. Metabolic labeling of COS-7 cells expressing two N-terminal GRIP1 proteins demonstrated that these proteins differed in their pattern of palmitoylation. These findings suggested that the molecular diversity of GRIP1 underlies the localization and functional heterogeneity of this protein.

Adaptor Proteins, Signal Transducing↗

Purkinje cell-specific and inducible gene recombination system generated from C57BL/6 mouse ES cells.

Spatiotemporally restricted gene targeting is needed for analyzing the functions of various molecules in a variety of biological phenomena. We have generated an inducible cerebellar Purkinje cell-specific gene targeting system. This was achieved by establishing a mutant mouse line (D2CPR) from a C57BL/6 mouse ES cell line, which expressed a fusion protein consisting of the Cre recombinase and the progesterone receptor (CrePR). The Purkinje cell-specific expression of CrePR was attained by inserting CrePR into the glutamate receptor delta2 subunit (GluRdelta2) gene, which was expressed specifically in the Purkinje cells. Using the transgenic mice carrying the Cre-mediated reporter gene, we showed that the antiprogesterone RU486 could induce recombinase activity of the CrePR protein specifically in the mature cerebellar Purkinje cells of the D2CPR line. Thus this mutant line will be a useful tool for studying the molecular function of mature Purkinje cells by manipulating gene expression in a temporally restricted manner.

Animals↗

Postsynaptic modulation of AMPA receptor-mediated synaptic responses and LTP by the type 3 ryanodine receptor.

The precise function of ryanodine receptors (RyRs) in synaptic transmission is unknown, but three of their subtypes are expressed in the brain. We examined the roleof RyRs in excitatory synaptic transmission in hippocampal slices, using type 3 RyR (RyR3)-deficient mice. The alpha-amino-3-hydroxy-5-methyl-4-isoxozolepropionic acid (AMPA) receptor-mediated basal synaptic responses in the CA1 region of mutant mice were smaller than those of wild-type mice, while there was no difference in N-methyl-d-aspartate receptor-mediated responses, suggesting selective postsynaptic modification of AMPA receptors by RyR3. The expression of synaptic AMPA receptor subunits examined by Western blotting or immunohistochemistry was indistinguishable, suggesting that the smaller AMPA synaptic responses in mutant mice were not due to the reduced number of synaptic AMPA receptors. Although the initial potentiation following tetanic stimulation of afferent fibers was similar, long-term potentiation (LTP) was smaller in mutant mice. There were no differences in presynaptic electrophysiological properties. We thus conclude that RyR3 postsynaptically regulates the properties of AMPA receptors and LTP.

2-Amino-5-phosphonovalerate↗

Clinicopathologic characteristics and survival of patients with clinical Stage I squamous cell carcinomas of the thoracic esophagus treated with three-field lymph node dissection.

OBJECTIVE: Clinicopathologic characteristics and survival rates of patients with clinical Stage I tumors treated with three-field lymph node dissection have not been well investigated. This report documents the results of a series of cases of clinical Stage I squamous cell carcinomas treated with this surgical procedure in our institute. METHODS: From January 1988 to March 1997, 326 patients with carcinomas of the thoracic esophagus underwent transthoracic esophagectomy with three-field lymph node dissection. Two hundred and ninety-seven (91%) of these had squamous cell carcinomas. Fifty-seven (18%) patients with clinical Stage I squamous cell carcinomas of the thoracic esophagus were retrospectively reviewed here. RESULTS: Among 57 clinical Stage I squamous cell carcinomas, ten (18%) were diagnosed as T1-mucosal and 47 (83%) as T1-submucosal. Seventy percent of the patients with clinical T1-mucosal tumors had additional primary esophageal lesions. The operative morbidity and in-hospital mortality rates were 63 and 0%, and the overall 1-, 3-, 5-, and 10-year survival rates were 95, 86, 78, and 70%, respectively. Of the 57 tumors assessed pathologically, 12 (21%) were T1-mucosal, 42 (74%) were T1-submucosal, and three (5%) were T2. Nineteen (33%) exhibited lymph node metastasis. The 1-, 3-, 5-, and 10-year survival rates for patients with lymph node metastasis were 90, 79, 73, and 58%, respectively, as compared with 97, 90, 80, and 76, respectively for patients without lymph node metastasis (P=0.24). The accuracy of preoperative staging, based on both wall penetration and the status regarding lymph node metastasis, was 63%. With reference to the 1997 UICC-TNM staging system, 36 (63%) were pStage I, two (4%) were pStage IIA, 18 (28%) were pStage IIB, and three (6%) were pStage IVB. The 1-, 3-, 5-, and 10-year survival rates for patients with pStage I disease were 97, 92, 85, and 81%, respectively. In those with pStage II or IV disease, the values were 91, 76, 65, and 52%, respectively. CONCLUSIONS: Three-field lymph node dissection may be indicated even for patients with clinical Stage I squamous cell carcinoma requiring surgical intervention because this surgical procedure provides for possible cure by removing unsuspected lymph node metastasis.

Aged↗

Effect of acetate on glycogen replenishment in liver and skeletal muscles after exhaustive swimming in rats.

Immediately after exhaustive swimming, rats were given one of the following orally: distilled water (W), glucose (G); acetic acid (A); citric acid (C); glucose and acetic acid (GA); and glucose and citric acid (GC), and they were killed 2 h after ingestion (each trial: n=4). Exhaustive exercise resulted in a significant reduction of the glycogen store in the gastrocnemius muscle. The glycogen stores in the liver were significantly higher following ingestion in groups GA and GC, in the gastrocnemius in groups G, GA and GC, and in the soleus in group GC, than immediately post exercise. These results suggest that oral acetic acid with glucose can facilitate liver glycogen restoration during the early period of recovery, and that acetate has about the same physiological effects as citrate on glycogen replenishment.

Acetic Acid↗

NMDA receptor subunits GluRepsilon1, GluRepsilon3 and GluRzeta1 are enriched at the mossy fibre-granule cell synapse in the adult mouse cerebellum.

Cerebellar N-methyl-D-aspartate (NMDA) receptors are concentrated in the granular layer and are involved in motor coordination and the induction of long-term potentiation at mossy fibre-granule cell synapses. In the present study, we used immunohistochemistry to examine the distribution of NMDA receptor subunits in the adult mouse cerebellum. We found that appropriate pepsin pretreatment of sections greatly enhanced the sensitivity and specificity of immunohistochemical detection. As a result, intense immunolabelling for GluRepsilon1 (NR2A), GluRepsilon3 (NR2C), and GluRzeta1 (NR1) all appeared in synaptic glomeruli of the granular layer. Double immunofluorescence showed that these subunits were colocalized in individual synaptic glomeruli. Within the glomerulus, NMDA receptor subunits were located between centrally-located huge mossy fibre terminals and peripherally-located tiny Golgi axon terminals. By immunoelectron microscopy, all three subunits were detected at the postsynaptic junction in granule cell dendrites, forming synapses with mossy fibre terminals. Consistent with the known functional localization, GluRepsilon1, GluRepsilon3, and GluRzeta1 are, thus, anatomically concentrated at the mossy fibre-granule cell synapse. By contrast, immunohistochemical signals were very low in Purkinje cell somata and dendrites in the molecular layer. The lack of GluRzeta1 immunolabelling in Purkinje cells was unexpected because the cells express GluRzeta1 mRNA at high levels and high levels of GluRzeta1 protein in the molecular layer were revealed by immunoblot. As Purkinje cells are exceptionally lacking GluRepsilon expression, the discrepant result may provide in vivo evidence suggesting the importance of accompanying GluRepsilon subunits in synaptic localization of GluRzeta1.

Animals↗

Acetic acid feeding enhances glycogen repletion in liver and skeletal muscle of rats.

To investigate the efficacy of the ingestion of vinegar in aiding recovery from fatigue, we examined the effect of dietary acetic acid, the main component of vinegar, on glycogen repletion in rats. Rats were allowed access to a commercial diet twice daily for 6 d. After 15 h of food deprivation, they were either killed immediately or given 2 g of a diet containing 0 (control), 0.1, 0.2 or 0.4 g acetic acid/100 g diet for 2 h. The 0.2 g acetic acid group had significantly greater liver and gastrocnemius muscle glycogen concentration than the control group (P < 0.05). The concentrations of citrate in this group in both the liver and skeletal muscles were >1.3-fold greater than in the control group (P > 0.1). In liver, the concentration of xylulose-5-phosphate in the control group was significantly higher than in the 0.2 and 0.4 g acetic acid groups (P < 0.01). In gastrocnemius muscle, the concentration of glucose-6-phosphate in the control group was significantly lower and the ratio of fructose-1,6-bisphosphate/fructose-6-phosphate was significantly higher than in the 0.2 g acetic acid group (P < 0.05). This ratio in the soleus muscle of the acetic acid fed groups was <0.8-fold that of the control group (P > 0.1). In liver, acetic acid may activate gluconeogenesis and inactivate glycolysis through inactivation of fructose-2,6-bisphosphate synthesis due to suppression of xylulose-5-phosphate accumulation. In skeletal muscle, acetic acid may inhibit glycolysis by suppression of phosphofructokinase-1 activity. We conclude that a diet containing acetic acid may enhance glycogen repletion in liver and skeletal muscle.

Acetic Acid↗

Improved immunohistochemical detection of postsynaptically located PSD-95/SAP90 protein family by protease section pretreatment: a study in the adult mouse brain.

Postsynaptic density (PSD)-95, SAP102, and Chapsyn-110 are members of the PSD-95/SAP90 protein family, which interact with the C-terminus of N-methyl-D-aspartate (NMDA) receptor and shaker-type potassium channel subunits. Here we report that appropriate section pretreatment with pepsin has led to qualitative and quantitative changes in light microscopic immunohistochemical detection of the protein family. First, pepsin pretreatment lowered the concentration of affinity-purified primary antibodies, while it greatly increased the intensity of immunoreactions. Second, the resulting overall distributions of PSD-95, SAP102, and Chapsyn-110 in the adult mouse brain were consistent with their mRNA distributions. Third, instead of the reported patterns of somatodendritic labeling, tiny punctate staining in the neuropil became overwhelming. Fourth, many PSD-95-immunopositive puncta were apposed closely to synaptophysin-positive nerve terminals and overlapped with NMDA receptor subunits. By postembedding immunogold, the PSD-95 antibody was shown to label exclusively the postsynaptic density at asymmetrical synapses. Based on these results, we conclude that antibody access and binding to the postsynaptically located PSD-95/SAP90 protein family are hindered when conventional immunohistochemistry is adopted, and that pepsin pretreatment effectively unmasks the postsynaptic epitopes. On the other hand, PSD-95 in axon terminals of cerebellar basket cells, where high levels of potassium channels are present, was detectable irrespective of pepsin pretreatment, suggesting that PSD-95 antibody is readily accessible to the presynaptic epitopes. Consequently, the present immunohistochemical results have provided light microscopic evidence supporting the prevailing notion that the PSD-95/SAP90 protein family interacts with NMDA receptor subunits and potassium channel subunits.

Animals↗

Developmental changes in expression of the three ryanodine receptor mRNAs in the mouse brain.

Ryanodine receptors (RyR) are Ca(2+)-induced Ca(2+) release channels located on the endoplasmic reticulum, and consist of three isoforms, termed RyR1-3. We examined their expression in developing mouse brains by in situ hybridization. During the embryonic stage, RyR1 mRNA levels were highest in the rostral cortical plate, whereas RyR3 mRNA was most prominent in the caudal cortical plate and hippocampus. Initially, low levels of RyR2 mRNA were distributed in the diencephalon and brainstem. However, from postnatal day 7 onward, RyR2 mRNA became the major isoform in many brain regions, while RyR1 mRNA became prominent in the dentate gyrus and Purkinje cell layer. Postnatal down-regulation in the caudal cerebral cortex restricted RyR3 mRNA expression to the hippocampus, particularly the CA1 region. Therefore, RyR expression undergoes dynamic changes during the early postnatal period, when neurons are undergoing structural and functional differentiation.

Animals↗

Dynamic transformation of Bergmann glial fibers proceeds in correlation with dendritic outgrowth and synapse formation of cerebellar Purkinje cells.

Bergmann glia (BG) are unipolar cerebellar astrocytes, whose radial (or Bergmann) fibers associate with developing granule cells and mature Purkinje cells (PCs). In the present study, we investigated the morphodifferentiation of BG by immunohistochemistry for glutamate transporter GLAST and electron microscopy. GLAST was expressed widely in cerebellar radial glia/astrocytes during fetal and neonatal periods and became concentrated in BG postnatally. During the second postnatal week when PC dendrites grow actively, GLAST immunostaining revealed dynamic cytologic changes in Bergmann fibers in a deep-to-superficial gradient; Bergmann fibers traversing the external granular layer were stained as rod-like fibers, whereas in the molecular layer, the rod-like pattern was gradually replaced with a reticular meshwork. At postnatal day 10, the superficial rod-like domain was composed of glial fibrillary acidic protein (GFAP)-positive/GLAST-positive straight fibers, forming cytoplasmic swellings and short filopodia. Along this domain, the tip of growing PC dendrites ascended vertically and entered the base of the external granular layer. The deeper reticular domain of Bergmann fibers was characterized by active expansion of GFAP-negative/GLAST-positive lamellate processes, which surrounded PC synapses almost completely. Therefore, the transformation of Bergmann fibers proceeds in correlation with dendritic differentiation of PCs. The intimate PC-BG relationships during cerebellar development raise the possibility that a preexisting glial shaft could serve as a structural substrate that directs dendritic outgrowth toward the pial surface, whereas the successive formation of a reticular glial meshwork should lead to structural maturation of newly formed PC synapses.

ATP-Binding Cassette Transporters↗

Gq protein alpha subunits Galphaq and Galpha11 are localized at postsynaptic extra-junctional membrane of cerebellar Purkinje cells and hippocampal pyramidal cells.

Following cell surface receptor activation, the alpha subunit of the Gq subclass of GTP-binding proteins activates the phosphoinositide signalling pathway. Here we examined the expression and localization of Gq protein alpha subunits in the adult mouse brain by in situ hybridization and immunohistochemistry. Of the four members of the Gq protein alpha subunits, Galphaq and Galpha11 were transcribed predominantly in the brain. The highest transcriptional level of Galphaq was observed in cerebellar Purkinje cells (PCs) and hippocampal pyramidal cells, while that of Galpha11 was noted in hippocampal pyramidal cells. Antibody against the C-terminal peptide common to Galphaq and Galpha11 strongly labelled the cerebellar molecular layer and hippocampal neuropil layers. In these regions, immunogold preferentially labelled the cytoplasmic face of postsynaptic cell membrane of PCs and pyramidal cells. Immunoparticles were distributed along the extra-junctional cell membrane of spines, dendrites and somata, but were almost excluded from the junctional membrane. By double immunofluorescence, Galphaq/Galpha11 was extensively colocalized with metabotropic glutamate receptor mGluR1alpha in dendritic spines of PCs and with mGluR5 in those of hippocampal pyramidal cells. Together with concentrated localization of mGluR1alpha and mGluR5 in a peri-junctional annulus on PC and pyramidal cell synapses (Baude et al. 1993, Neuron, 11, 771-787; Luján et al. 1996, Eur. J. Neurosci., 8, 1488-1500), the present molecular-anatomical findings suggest that peri-junctional stimulation of the group I metabotropic glutamate receptors is mediated by Galphaq and/or Galpha11, leading to the activation of the intracellular effector, phospholipase Cbeta.

Amino Acid Sequence↗

Acetic acid suppresses the increase in disaccharidase activity that occurs during culture of caco-2 cells.

To understand how blood glucose level is lowered by oral administration of vinegar, we examined effects of acetic acid on glucose transport and disaccharidase activity in Caco-2 cells. Cells were cultured for 15 d in a medium containing 5 mmol/L of acetic acid. This chronic treatment did not affect cell growth or viability, and furthermore, apoptotic cell death was not observed. Glucose transport, evaluated with a nonmetabolizable substrate, 3-O-methyl glucose, also was not affected. However, the increase of sucrase activity observed in control cells (no acetic acid) was significantly suppressed by acetic acid (P < 0.01). Acetic acid suppressed sucrase activity in concentration- and time-dependent manners. Similar treatments (5 mmol/L and 15 d) with other organic acids such as citric, succinic, L-maric, L-lactic, L-tartaric and itaconic acids, did not suppress the increase in sucrase activity. Acetic acid treatment (5 mmol/L and 15 d) significantly decreased the activities of disaccharidases (sucrase, maltase, trehalase and lactase) and angiotensin-I-converting enzyme, whereas the activities of other hydrolases (alkaline phosphatase, aminopeptidase-N, dipeptidylpeptidase-IV and gamma-glutamyltranspeptidase) were not affected. To understand mechanisms underlying the suppression of disaccharidase activity by acetic acid, Northern and Western analyses of the sucrase-isomaltase complex were performed. Acetic acid did not affect the de novo synthesis of this complex at either the transcriptional or translational levels. The antihyperglycemic effect of acetic acid may be partially due to the suppression of disaccharidase activity. This suppression seems to occur during the post-translational processing.

Acetic Acid↗

Why do patients with atopic dermatitis refuse to apply topical corticosteroids?

BACKGROUND: The number of patients with atopic dermatitis who refuse to use topical corticosteroids because of personal fears seems to be increasing. However, studies on this subject are scarce. Consequently, we have investigated this issue further. METHODS: A cross-sectional study based on a questionnaire. Between September 1998 and January 1999, a questionnaire was distributed to patients who responded to an announcement and to those attending 18 hospitals or clinics and 11 self-help groups throughout Japan to identify what makes patients resistant to applying topical corticosteroids. RESULTS: Patients who are reluctant to use topical corticosteroids often experienced: ineffective or short-lasting results, adverse side effects and feelings of distrust towards their physician. These feelings of distrust were found to be significantly stronger among patients who were reluctant to apply topical corticosteroids than among patients who accepted the treatment with little or no feelings of resistance. External influences such as those from family members, acquaintances, mass media (television, newspapers and magazines), alternative 'nondoctor' therapists and self-help groups were not found to be a significant factor between both groups. However, the influence of the physician was found to be significant and directly related to the patients' lack of trust. CONCLUSIONS: Patients with atopic dermatitis who refuse to use topical corticosteroids attribute their feelings of resistance to personal experiences rather than to information from external sources. Information or warnings about associated side effects from physicians may help to reduce these fears and ultimately benefit the physician-patient relationship.

Administration, Topical↗

Impairment of AMPA receptor function in cerebellar granule cells of ataxic mutant mouse stargazer.

The spontaneous recessive mutant mouse stargazer (stg) begins to show ataxia around postnatal day 14 and display a severe impairment in the acquisition of classical eyeblink conditioning in adulthood. These abnormalities have been attributed to the specific reduction in brain-derived neurotrophic factor (BDNF) and the subsequent defect in TrkB receptor signaling in cerebellar granule cells (GCs). In the stg mutant cerebellum, we found that EPSCs at mossy fiber (MF) to GC synapses are devoid of the fast component mediated by AMPA-type glutamate receptors despite the normal slow component mediated by NMDA receptors. The sensitivity of stg mutant GCs to exogenously applied AMPA was greatly reduced, whereas that to NMDA was unchanged. Glutamate release from MF terminals during synaptic transmission to GCs appeared normal. By contrast, AMPA receptor-mediated EPSCs were normal in CA1 pyramidal cells of the stg mutant hippocampus. Thus, postsynaptic AMPA receptor function was selectively impaired in stg mutant GCs, although the transcription of four AMPA receptor subunit genes in the stg GC was comparable to the wild-type GC. We also examined the cerebellum of BDNF knockout mice and found that their MF-GC synapses had a normal AMPA receptor-mediated EPSC component. Thus, the impaired AMPA receptor function in the stg mutant GC is not likely to result from the reduced BDNF-TrkB signaling. These results suggest that the defect in MF to GC synaptic transmission is a major factor that causes the cerebellar dysfunction in the stg mutant mouse.

6-Cyano-7-nitroquinoxaline-2,3-dione↗

Distinct spatiotemporal expression of mRNAs for the PSD-95/SAP90 protein family in the mouse brain.

PSD-95 (SAP90), SAP102 and Chapsyn-110 (PSD-93) are members of the membrane-associated guanylate kinase family, and interact with N-methyl-D-aspartate (NMDA) receptor NR2A (GluRepsilon1) and NR2B (GluRepsilon2) subunits and with Shaker-type K+ channel subunits to cluster into a channel complex. In the present study, we examined their expression in developing and adult mouse brains by in situ hybridization with antisense oligonucleotide probes. PSD-95 and SAP102 mRNAs were prominently expressed at embryonic day 13 (E13) in the mantle zone of various brain regions, where NMDA receptor NR2B subunit mRNA is expressed at high levels. In the early postnatal period when active synaptogenesis takes place, both mRNAs became elevated and concentrated in the telencephalon and cerebellar granular layer, where NR2A and/or NR2B subunit mRNAs are abundantly expressed. Chapsyn-110 mRNA was, though at low levels, found over the mantle zone of embryonic brains, and the level was progressively increased in the telencephalon starting at perinatal stages. The spatial and temporal correlations in the brain in vivo suggest that the PSD-95/SAP90 protein family can interact with NMDA receptor subunits to cluster them into channel complex at both synaptic and non-synaptic sites before, during and after synaptogenic stages.

Aging↗