Biomedical subjects

A Kato

Publications and source records attributed to A Kato.

At least 217 records · Page 12Linked to original sources

PubMed1998

Molecular cloning, localization, and developmental expression of mouse brain finger protein (Bfp)/ZNF179: distribution of bfp mRNA partially coincides with the affected areas of Smith-Magenis syndrome.

Bfp (brain finger protein) is a member of the RING finger protein family, which is highly expressed in the brain. We have previously shown that one copy of the human bfp gene, mapped at 17p11.2, was actually deleted in six of six Smith-Magenis syndrome (SMS) patients. Now we have isolated the mouse bfp cDNA. Using in situ hybridization and immunohistochemistry, the distribution of mouse bfp mRNA and protein was identified especially in neural cells of the cerebral cortex, hippocampus, lateral amygdaloid nucleus, and ventromedial hypothalamus. In primary culture of the whole brain in a neonatal mouse, the Bfp protein was detected in both neuron and glial cells, and its subcellular localization was predominantly in the nucleus, but some amounts were also found in the cytoplasm. The bfp mRNA was also expressed strongly in the marginal zone of brain vesicles, optic stalk, and cartilage primordium, which are part of the critical tissues frequently involved in SMS patients, and in such tissues as nasal epithelium and primordium of follicles in a 13. 5-dpc embryo. Subsequently, its amount in the developing brain further increased during embryogenesis, reaching the highest level in the adult brain. These findings suggest a possibility that Bfp might be involved in the pathogenesis of Smith-Magenis syndrome as a regulator protein related to neural differentiation and function.

Abnormalities, Multiple↗

PubMed1998

Novel members of the Vesl/Homer family of PDZ proteins that bind metabotropic glutamate receptors.

Vesl-1S (186 amino acids, also called Homer) is a protein containing EVH1- and PDZ-like domains whose expression in the hippocampus is regulated during long term potentiation (LTP), one form of synaptic plasticity thought to underlie memory formation (Kato, A., Ozawa, F., Saitoh, Y., Hirai, K., and Inokuchi, K. (1997) FEBS Lett. 412, 183-189; Brakeman, P. R., Lanahan, A. A., O'Brien, R., Roche, K., Barnes, C. A., Huganir, R. L., and Worley, P. F. (1997) Nature 386, 284-288). Here we report additional members of the Vesl/Homer family of proteins, Vesl-1L and Vesl-2. Vesl-1L (366 amino acids), a splicing variant of Vesl-1S, shares N-terminal 175 amino acids with Vesl-1S and contains additional amino acids at the C terminus. Vesl-2 (354 amino acids) was highly related to Vesl-1L in that both contain EVH1- and PDZ-like domains at the N terminus (86% conservation) and an MCC (mutated in colorectal cancer)-like domain and a leucine zipper at the C terminus. In contrast to vesl-1S, we observed no changes in the levels of vesl-1L and vesl-2 mRNAs during dentate gyrus LTP. All these proteins interacted with metabotropic glutamate receptors (mGluR1 and mGluR5) as well as several hippocampal proteins in vitro. Vesl-1L and Vesl-2, but not Vesl-1S, interacted with each other through the C-terminal portion that was absent in Vesl-1S. Vesl-1L and Vesl-2 may mediate clustering of mGluRs at synaptic junctions. We propose that Vesl-1S may be involved in the structural changes that occur at metabotropic glutamatergic synapses during the maintenance phase of LTP by modulating the redistribution of synaptic components.

Amino Acid Sequence↗

PubMed1998

Neuropeptide specificity and inhibition of recombinant isoforms of the endopeptidase 3.4.24.16 family: comparison with the related recombinant endopeptidase 3.4.24.15.

Endopeptidase EC 3.4.24.16 (EP24.16c, neurolysin) and thimet oligopeptidase EC 3.4.24.15 are close related members of a large family of metalloproteases. Besides their cytosolic and membrane bound form, endopeptidase EC 3.4.24.16 appears to be present in the inner membrane of the mitochondria (EP24.16m). We have overexpressed two porcine EP24.16 isoforms in E. coli and purified the recombinant proteins to homogeneity. We show here that these peptidases hydrolyse a series of neuropeptides with similar rates and at sites reminiscent of those elicited by classically purified human brain EP24.16c. All neuropeptides, except neurotensin, were similarly cleaved by recombinant endopeptidase 3.4.24.15 (EP24.15, thimet oligopeptidase), another zinc-containing metalloenzyme structurally related to EP24.16. These two EP24.16 isoforms were drastically inhibited by Pro-Ile and dithiothreitol and remained unaffected by a specific carboalkyl inhibitor (CFP-AAY-pAb) directed toward the related EP24.15. The present purification procedure of EP24.16 should allow to establish, by mutagenesis analysis, the mechanistic properties of the enzyme.

Amino Acid Sequence↗

PubMed1998

Active sodium-urea counter-transport is inducible in the basolateral membrane of rat renal initial inner medullary collecting ducts.

Rat inner medullary collecting ducts (IMCD3s) possess a luminal Na+-dependent, active urea secretory transport process, which is upregulated by water diuresis. In this study of perfused IMCDs microdissected from base (IMCD1), middle (IMCD2), or tip (IMCD3) of the inner medulla, we tested whether furosemide diuresis alters active urea transport. Rats received furosemide (10 mg/d s.c. for 3-4 d) and were compared with pair-fed control rats. Furosemide significantly decreased urine osmolality and urea clearance, and increased blood urea nitrogen. IMCD3s from furosemide-treated rats had significantly lower rates of active urea secretion than IMCD3s from control rats. IMCD2s showed no active urea transport in control or furosemide-treated rats. IMCD1s from control rats had no active urea transport, but IMCD1s from furosemide-treated rats expressed significant rates of active urea reabsorption. In IMCD1s, this active urea reabsorptive transport process was inhibited by: (i) 0. 25 mM phloretin (bath); (ii) 1 mM ouabain (bath); and (iii) replacing bath Na+ with NMDG+; it was stimulated by 10 nM bumetanide (bath). In summary, we found that furosemide decreased active urea secretion in IMCD3s and induced active urea reabsorption in IMCD1s. The new Na+- dependent, active urea reabsorptive transport process may be a basolateral Na+-urea antiporter.

Amiloride↗

PubMed1998

Homonojirimycin isomers and N-alkylated homonojirimycins: structural and conformational basis of inhibition of glycosidases.

A series of natural epimers of alpha-homonojirimycin and its N-alkylated derivatives have been prepared to investigate the contribution of the different chiral centers and conformation of the specificity and potency of inhibition of glycosidases. These epimers and N-alkylated derivatives are alpha-homonojirimycin (1), beta-homonojirimycin (2), alpha-homomannojirimycin (3), beta-homomannojirimycin (4), alpha-3,4-di-epi-homonojirimycin (5), beta-4,5-di-epi-homonojirimycin (6), N-methyl-alpha-homonojirimycin (7), and N-butyl-alpha-homonojirimycin (8). Compound 1 was a potent inhibitor of a range of alpha-glucosidases with IC50 values of 1 to 0.01 microM. Compounds 2, 3, and 4 were surprisingly inactive as inhibitors of beta-glucosidase and alpha- and beta-mannosidases but were moderately good as inhibitors of rice and some mammalian alpha-glucosidases. Compound 4 was active in the micromolar range toward all alpha-glucosidases tested. Furthermore, compound 4, which superimposes well on beta-l-fucose, was a 10-fold more effective inhibitor of alpha-l-fucosidase than 1-deoxymannojirimycin (12) and 3, with a Ki value of 0.45 microM. Only compounds 5 and 6 showed inhibitory activity toward alpha- and beta-galactosidases (6with an IC50 value of 6.4 microM against alpha-galactosidase). The high-resolution structure of 1 has been determined by X-ray diffraction and showed a chair conformation with the C1 OH (corresponding to the C6 OH in 1-deoxynojirimycin) predominantly equatorial to the piperidine ring in the crystal structure. This preferred (C1 OH equatorial) conformation was also corroborated by 1H NMR coupling constants. The coupling constants for 7 suggest the axial orientation of the C1 OH, while in 8 the C1 OH axial conformation was not observed. The C1 OH axial conformation appears to be responsible for more potent inhibition toward processing alpha-glucosidase I than alpha-glucosidase II. It has been assumed that the anti-HIV activity of alkaloidal glycosidase inhibitors results from the inhibition of processing alpha-glucosidase I, but 1, 7, and 8 were inactive against HIV-1 replication at 500 microg/mL as measured by inhibition of virus-induced cytopathogenicity in MT-4 cells. In contrast, the EC50 value for N-butyl-1-deoxynojirimycin (11), which also inhibits processing alpha-glucosidase I, was 37 microg/mL. Compound 7 has been shown to be a better inhibitor of alpha-glucosidase I than 1 and 8 both in vitro and in the cell culture system. These data imply that inhibition of HIV by glycosidase inhibitors can be due to factors other than simply inhibition of processing alpha-glucosidase I.

1-Deoxynojirimycin↗

PubMed1998

Monoclonal origin of an esophageal carcinosarcoma producing granulocyte-colony stimulating factor: a case report.

BACKGROUND: Carcinosarcomas are comprised of carcinomatous and sarcomatous elements, and their histogenesis remains unclear. The authors examined the serum concentrations of hematopoietic growth factors and performed immunohistochemical studies on an esophageal carcinosarcoma from a patient with marked granulocytosis to determine its histopathogenesis and clonality. METHODS: The authors examined the case of a 63-year-old man with a polypoid tumor of the esophagus associated with marked leukocytosis (131 x 10(9) per liter). Immunohistochemical staining of the esophageal tumor was performed using monoclonal antibodies against granulocyte-colony stimulating factor (G-CSF), keratin, epithelial membrane antigen (EMA), and vimentin. RESULTS: The patient's leukocyte count was increased (124 x 10(9) per liter) on admission. Because mature granulocytes predominantly were increased despite the absence of apparent infection, the patient's serum G-CSF concentration was examined and found to be 286.0 pg/mL and to increase with time. After thoracic esophagectomy was performed, granulocyte count and serum G-CSF concentration rapidly normalized. G-CSF concentration was 50-fold higher in the tumor tissue extract than in the extract from normal esophageal tissue. Microscopic examination of the resected specimens revealed that the tumor was comprised of squamous cell carcinoma (SCC) and spindle-shaped sarcomatous elements, and transitional features were observed within these two components. Immunohistochemical examination disclosed cells that were positive for keratin and EMA in the carcinomatous element and vimentin positive cells in the sarcomatous element. However, both types of tumor cells were positive for G-CSF. CONCLUSIONS: The presence of G-CSF in both SCC cells and spindle-shaped sarcomatous cells indicated that these two components originated from a single clone.

Carcinosarcoma↗

PubMed1998

Anti-HIV-1 and chemotactic activities of human stromal cell-derived factor 1alpha (SDF-1alpha) and SDF-1beta are abolished by CD26/dipeptidyl peptidase IV-mediated cleavage.

CD26 is a leukocyte-activation antigen that is expressed on T lymphocytes and macrophages and possesses dipeptidyl peptidase IV (DPPIV) activity, whose natural substrates have not been identified yet. CXC chemokines, stromal cell-derived factor 1alpha (SDF-1alpha) and 1beta (SDF-1beta), sharing the receptor CXCR-4, are highly efficacious chemoattractants for resting lymphocytes and CD34(+) progenitor cells, and they efficiently block the CXCR-4-mediated entry into cells of T cell line tropic strains of HIV type 1 (HIV-1). Here we show that both the chemotactic and antiviral activities of these chemokines are abrogated by DPPIV-mediated specific removal of the N-terminal dipeptide, not only when the chemokines are produced in transformed mouse L cell line to express human CD26 but also when they were exposed to a human T cell line (H9) physiologically expressing CD26. Mutagenesis of SDF-1alpha confirmed the critical requirement of the N-terminal dipeptide for its chemotactic and antiviral activities. These data suggest that CD26-mediated cleavage of SDF-1alpha and SDF-1beta likely occurs in human bodies and promotes HIV-1 replication and disease progression. They may also explain why memory function of CD4(+) cells is preferentially lost in HIV-1 infection. Furthermore, CD26 would modulate various other biological processes in which SDF-1alpha and SDF-1beta are involved.

Animals↗

PubMed1998

Neuromagnetic fields preceding unilateral movements in dextrals and sinistrals.

Movement-related magnetic fields were recorded with a whole-head magnetoencephalographic system in three dextrals and three sinistrals during right or left index finger extension. The motor field (MF) demonstrated an asymmetrical isofield map pattern with larger field reversal over the contralateral hemisphere for dominant hand movement and an almost symmetrical pattern for non-dominant hand movement in each subject. The equivalent current dipole moment of the MF for the contralateral hemisphere was significantly larger than the ipsilateral hemisphere for dominant hand movement, and almost equal for both hemispheres for non-dominant hand movement. These results were congruent for both dextrals and sinistrals, suggesting a more important role of the hemisphere contralateral to the dominant hand in unilateral voluntary movement, regardless of handedness.

Brain↗

PubMed1998

Stochastic determination of the chromosomal region responsible for expression of human glial fibrillary acidic protein in astrocytic tumors.

Previous investigators have localized the human glial fibrillary acidic protein (GFAP) gene in the segment 17q21 in chromosome 17. In the present study, we statistically assessed the association between the allelic status in thirty-three microsatellite loci and the immunohistochemical expression of GFAP in twenty human astrocytic tumors. The results demonstrated that the loss of heterozygosity in only one locus (D17S795 located in 17q21.2) was significantly associated with the impaired expression of GFAP (P = 0.0280, Pc = 0.0384 by Fisher's exact test). The adjacent loci located in 17q21.1 and 17q21.3 were not relevant to GFAP expression. Those data suggest that the critical region responsible for GFAP expression (coding sequence and regulatory elements) is located close to the locus D17S795 in the segment 17q21.2.

Astrocytoma↗

PubMed1998

Importance of the N-glycan in the V3 loop of HIV-1 envelope protein for CXCR-4- but not CCR-5-dependent fusion.

The V3 region of HIV-1 envelope protein possesses a single N-linked sugar chain, which is conserved in most HIV-1 strains. We studied its role in the life cycle of HIV-1 strains with different co-receptor usage. Removal of the glycan appeared to cause a marked reduction of CXCR-4- but not CCR-5-dependent virus entry. A basic amino acid substitution at the 11th position of V3 markedly compensated for the removal of the N-glycan. These results indicate that the N-glycan plays an important role for CXCR-4-dependent virus entry and that this role is exerted in a particular context of the peptide backbone.

Amino Acid Sequence↗

PubMed1998

Nonsteroidal anti-inflammatory drugs may delay the repair of gastric mucosa by suppressing prostaglandin-mediated increase of hepatocyte growth factor production.

Prostaglandins (PGs), hepatocyte growth factor (HGF), and induction of cyclooxygenase (PG synthetase, COX) play important roles in the repair process of gastric mucosa. We hypothesized that nonsteroidal anti-inflammatory drugs (NSAIDs), including indomethacin (IND), retard the healing of ulcers by suppressing these factors. In this study, we investigated the effects of cytokines, growth factors, and IND on production of PG and HGF, and induction of COX using cultured human gastric fibroblasts. Exogenous PGs significantly increased HGF production in a dose-dependent manner. Among various potential stimulants tested, interleukin-1 beta (IL-1 beta) dramatically increased PGE2 production and significantly stimulated HGF production. IL-1 beta induced COX-2 but not COX-1 protein. IND significantly reduced both basal and IL-1 beta-induced PGE2 release and HGF production. These results suggest that the IL-1 beta-PG-HGF pathway plays a role in the repair process of gastric mucosa. Further, NSAIDs may delay the healing of gastric mucosal ulcer, in part through suppression of HGF expression via inhibition of endogenous PG production.

Alprostadil↗

PubMed1998

Regulation of cyclin D-dependent kinase activity in rat liver regeneration.

The regulation of cyclin D-dependent kinase activity in tissue regeneration in vivo has not been fully described. In young adult rat liver after 70% partial hepatectomy, the association of cyclin D1 with cdk4 was significantly promoted during G1 phase and was maximal at 18 hr, corresponding mainly to late G1. Cyclin D1-dependent kinase activity also strongly increased during G1 phase. The timing of the induction of cyclin D1 / cdk4 complex assembly correlated well with that of cyclin D1-dependent kinase activity. At 18 hr after partial hepatectomy, the amounts of CDK inhibitors p21(CIP1) and p27(KIP1) were also maximal, while only one-tenth of p21(CIP1) and of p27(KIP1) was associated with cyclin D1. These findings suggest that cyclin D1, cdk4 and their association act as promoting factors, and that both p21(CIP1) and p27(KIP1) may have physiological functions as adaptor proteins in additions to their roles as CDK inhibitors in rat liver regeneration.

Animals↗

PubMed1998

Molecular characterization of a glyoxysomal long chain acyl-CoA oxidase that is synthesized as a precursor of higher molecular mass in pumpkin.

A cDNA clone for pumpkin acyl-CoA oxidase (EC 1.3.3.6; ACOX) was isolated from a lambdagt11 cDNA library constructed from poly(A)+ RNA extracted from etiolated cotyledons. The inserted cDNA clone contains 2313 nucleotides and encodes a polypeptide of 690 amino acids. Analysis of the amino-terminal sequence of the protein indicates that the pumpkin acyl-CoA oxidase protein is synthesized as a larger precursor containing a cleavable amino-terminal presequence of 45 amino acids. This presequence shows high similarity to the typical peroxisomal targeting signal (PTS2). Western blot analysis following cell fractionation in a sucrose gradient revealed that ACOX is localized in glyoxysomes. A partial purification of ACOX from etiolated pumpkin cotyledons indicated that the ACOX cDNA codes for a long chain acyl-CoA oxidase. The amount of ACOX increased and reached to the maximum activity by day 5 of germination but decreased about 4-fold on the following days during the subsequent microbody transition from glyoxysomes to leaf peroxisomes. By contrast, the amount of mRNA was already high at day 1 of germination, increased by about 30% at day 3, and faded completely by day 7. These data indicated that the expression pattern of ACOX was very similar to that of the glyoxysomal enzyme 3-ketoacyl-CoA thiolase, another marker enzyme of the beta-oxidation spiral, during germination and suggested that the expression of each enzyme of beta-oxidation is coordinately regulated.

Acyl-CoA Oxidase↗

PubMed1998

Evidence for a 1 alpha,25-dihydroxyvitamin D3 receptor/binding protein in a membrane fraction isolated from a chick tibial fracture-healing callus.

Previous biological studies have implicated two vitamin D metabolites, 1 alpha,25(OH)2-vitamin D3[1 alpha,25(OH)2-D3] and 24R,25(OH)2-vitamin D3 [24R,25(OH)2D3] in the process of skeletal fracture-healing. While a nuclear receptor for 1 alpha,25(OH)2D3 is known to be present in osteoblast and absent in osteoclast cell lines, no systematic study has been carried out on the callus tissue which is formed during fracture-healing. The present report shows that a binding protein/receptor for 1 alpha,25(OH)2D3 resides both in a postnuclear membrane fraction and in a high speed cytosol fraction of the callus tissue obtained 10 days after imposition of a tibial fracture. The dissociation constant, KD, for 1 alpha,25(OH)2D3 was 0.83 +/- 0.34 M and 0.66 +/- 0.38 nM respectively, for the membrane and cytosol fractions. Results from a panel of steroid competition assays indicate that both receptor/binding proteins greatly prefer 1 alpha-hydroxylated ligands as compared to 1 alpha-deoxy or 24-hydroxylated ligands. The presence of 1 alpha,25(OH)2D3 receptors in the fracture-healing callus is consistent with the known biological effects of the metabolite on the fracture-healing process.

Animals↗

PubMed1998

Large quantity production with extreme convenience of human SDF-1alpha and SDF-1beta by a Sendai virus vector.

We describe a robust expression of human stromal cell-derived factor-1alpha (SDF-1alpha) and SDF-1beta, the members of CXC-chemokine family, with a novel vector system based upon Sendai virus, a non-segmented negative strand RNA virus. Recombinant SDF-1alpha and SDF-1beta were detected as a major protein species in culture supernatants, reached as high as 10 microg/ ml. This remarkable enrichment of the products allowed us to use even the crude supernatants as the source for biological and antiviral assays without further concentration nor purification and will thus greatly facilitate to screen their genetically engineered derivatives.

Anti-HIV Agents↗

PubMed1998

Aberrant muscle activation in patients after resection of non-primary motor areas: demonstration by surface electromyography.

Two patients presented with a tumor involving mainly the supplementary motor area or the premotor cortex. Shortly after tumor resection, each developed transient impairment of voluntary movements. An electromyogram, with the skin electrodes placed over the muscles of the upper arms and forearms, demonstrated aberrant ipsilateral, contralateral or bilateral muscle activation during unilateral motor tasks in both patients. The bilateral activation was more prominent in the patient who had an intact dominant hemisphere. The present study suggests for the first time the importance of non-primary motor areas of the human brain in activating the proper set of muscles on the proper side of the body.

Adult↗

PubMed1998

Cataloging altered gene expression during rat hippocampal long-term potentiation by means of differential display.

We have employed mRNA differential display (DD) to generate a catalog of cDNAs whose expression in the hippocampus was regulated during long-term potentiation (LTP) in dentate gyrus of anesthetized rats. DD with 459 combinations of primer pairs revealed that 80 out of approximately 70000 bands displayed showed a reproducible change in their expression level. These cDNAs were categorized into seven groups according to changes in their temporal expression pattern. Some of these cDNAs were induced rapidly, but transiently, after the LTP induction, some induced rapidly and persistently, some induced slowly, and some down-regulated following LTP. This suggests that a complex molecular hierarchy underlies the maintenance of hippocampal LTP.

Animals↗

PubMed1998

Novel structural difference between nopaline- and octopine-type trbJ genes: construction of genetic and physical map and sequencing of trb/traI and rep gene clusters of a new Ti plasmid pTi-SAKURA.

We constructed a gene library of a nopaline-type Ti plasmid (called pTi-SAKURA) which was newly isolated from Agrobacterium tumefaciens MAFF301001 of a Japanese cherry tree. The partial sequencing data, which were distributed over the entire plasmid genome, made it possible to assign typical Ti-encoded genes including trb and rep gene clusters. The trb/traI and rep gene clusters were sequenced completely. All the genes in the regions except trbJ were homologous with the corresponding genes on octopine-type Ti plasmids, based on both ORF size and sequence similarity. The trbJ on pTi-SAKURA is similar to that of an octopine-type Ti, but has an extra 282-base segment in its central domain. The above gene organization and sequences suggest a divergence of Ti plasmid during evolution in relation to Rhizobium plasmids, and is discussed in this paper.

Agrobacterium tumefaciens↗