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Biomedical subjects

M Deguchi

Publications and source records attributed to M Deguchi.

At least 37 records · Page 2Linked to original sources
PubMed2000

A novel transcriptional factor with Ser/Thr kinase activity involved in the transforming growth factor (TGF)-beta signalling pathway.

Transforming growth factor-beta (TGF-beta) shows a variety of biological activities in various organs or cells. Recently some factors such as Smads (Sma and Mad proteins) and TGF-beta activating kinase 1 ('TAK1') have been characterized as signalling molecules downstream of TGF-beta. Several TGF-beta response elements have been identified such as cAMP response element, Smad binding element, and recognition sites for activating protein-1 and stimulating protein-1 in various gene promoters. We also reported a TGF-beta response element in the human C-type natriuretic peptide (CNP) gene promoter. In this paper, we report on a novel factor which regulates the TGF-beta response promoter. This factor, named TSF1 (TGF-beta stimulated factor 1), possessed DNA-binding ability and activated the TGF-beta responsive CNP promoter or vascular endothelial growth factor gene promoter which possesses a sequence element analogous to the TGF-beta responsive GC-rich element of the CNP promoter. TSF1 did not directly activate a Smads-dependent promoter from plasminogen activator inhibitor 1 gene, but it showed enhancement in co-operation with Smad3 and Smad4. Interestingly, this factor had the structural features of a Ser/Thr kinase and actually exhibited protein kinase activity. TSF1 mRNA as well as its protein level were stimulated by TGF-beta treatment. Thus, TSF1 is an unique factor with two biological functions, transcriptional regulation and protein phosphorylation, that may be involved in TGF-beta signals.

Amino Acid Sequence↗
PubMed2000

Three isoforms of synaptic scaffolding molecule and their characterization. Multimerization between the isoforms and their interaction with N-methyl-D-aspartate receptors and SAP90/PSD-95-associated protein.

The synaptic scaffolding molecule (S-SCAM) has been identified as a protein interacting with SAP90/PSD-95-associated protein (SAPAP) (also called guanylate kinase-associated protein/hDLG-associated protein). S-SCAM has six PDZ (we have numbered them PDZ-0 to -5), two WW, and one guanylate kinase (GK) domains and interacts with N-methyl-D-aspartate (NMDA) receptor via PDZ-5 and SAPAP via the GK domain. We have identified here shorter isoforms of S-SCAM that start at the 164th or 224th methionine, and we renamed the original one, S-SCAMalpha, the middle one, S-SCAMbeta, and the shortest one, S-SCAM-gamma. S-SCAMbeta and -gamma have five PDZ (PDZ-1 to -5), two WW, and one GK domains. S-SCAMalpha interacted with S-SCAMbeta and -gamma through the region containing PDZ-4 and -5. The region containing both of PDZ-4 and -5 is sufficient for the clustering of NMDA receptors and forms a dimer in gel filtration, suggesting that S-SCAM forms multimers via the interaction between the C-terminal PDZ domains and assembles NMDA receptors into clusters. S-SCAMbeta and -gamma also interacted with SAPAP, suggesting that the N-terminal region of the GK domain is not necessary for the interaction. Finally, we have identified the interaction of the PDZ domains of S-SCAM with the GK domain of PSD-95/SAP90. S-SCAM, PSD-95/SAP90, and SAPAP are colocalized at least in some part in brain. Therefore, S-SCAM, PSD-95/SAP90, and SAPAP may form a complex in vivo.

Adaptor Proteins, Signal Transducing↗
PubMed2000

Association of synapse-associated protein 90/ postsynaptic density-95-associated protein (SAPAP) with neurofilaments.

BACKGROUND: Synapse-associated protein (SAP) 90/Postsynaptic density (PSD)-95-associated protein (SAPAP) (also called Guanylate kinase-associated protein/hDLG-associated protein) interacts with the guanylate kinase domains of PSD-95 and synaptic scaffolding molecule (S-SCAM) via the middle region containing 5 repeats of 14 amino acids. SAPAP also binds the recently identified proteins, nArgBP2 and synamon (also called Shank 1a), via the proline-rich region and the C-terminus, respectively. SAPAP is highly enriched in the Triton X-100-insoluble PSD fraction, and recruits PSD-95 into the Triton X-100-insoluble fraction in transfected cells. We have further characterized here the Triton X-100-insolubility of SAPAP and tried to identify the Triton X-100-insoluble structures which SAPAP interacts with. RESULTS: N-Methyl-D-aspartate receptors were recruited into the Triton X-100-insoluble fraction with PSD-95 by SAPAP. The N-terminal region of SAPAP was Triton X-100-insoluble, whereas the middle and C-terminal regions were Triton X-100-soluble. We identified proteins interacting with 35S-methionine-labelled SAPAP in the overlay assay, determined their amino acid sequences, and found them to be neurofilaments. SAPAP interacted with neurofilaments via the N-terminal region, was co-immunoprecipitated with neurofilaments from the rat brain, and co-localized with neurofilaments in transfected cells. CONCLUSION: SAPAP associates with neurofilaments via the N-terminal region and may link various components of the PSD to neurofilaments.

Actin Cytoskeleton↗
PubMed2000

Influenza virus-induced encephalopathy: clinicopathologic study of an autopsied case.

BACKGROUND: Rapid progressive encephalopathy with a high fever, consciousness loss and recurrent convulsions has been occasionally reported in children during influenza pandemics in Japan since 1995. We examined a 2-year old girl with hemorrhagic shock and encephalopathy syndrome associated with acute influenza A virus infection (A/Nagasaki/76/98; H3N2), to answer several questions for which no histologic or virologic data exist. METHODS: A clinicopathologic study using immunohistochemical staining and viral genome detection by reverse transcriptase polymerase chain reaction (RT-PCR) was performed with this autopsied case. RESULTS: The virus antigen was positive in CD8+ T lymphocytes from the lung and spleen. The virus infected a very limited part of the brain, especially Purkinje cells in the cerebellum and many neurons in the pons, without inducing an overt immunologic reaction from the host. The RT-PCR used for detecting the hemagglutinin gene demonstrated positive bands in all frozen tissues and cerebrospinal fluid taken at autopsy and not in samples obtained on admission. CONCLUSIONS: The pathologic change induced by the direct viral invasion cannot be responsible for all of the symptoms, especially for the rapid and severe clinical course of the disease within 24-48 h after the initial respiratory symptoms. Together with the rapid production of several inflammatory cytokines, the breakdown of the blood-brain barrier may induce severe brain edema and can be a major pathologic change for the disease. Any therapeutic strategy to control this multistep progression of the disease could be effective.

Antigens, Viral↗
PubMed1999

Localization of membrane-associated guanylate kinase (MAGI)-1/BAI-associated protein (BAP) 1 at tight junctions of epithelial cells.

Membrane-associated guanylate kinase (MAGI)-1/BAI-associated protein (BAP) 1 and Synapse-associated protein (SAP) 97/human Discs-large tumor suppressor gene (hDLG) are ubiquitous isoforms of synaptic scaffolding molecule (S-SCAM) and Postsynaptic density (PSD)-95/SAP90, both of which are implicated in the structures of synapses, respectively. SAP97/hDLG is localized at epithelial junctions and may function as a scaffolding protein, but the subcellular localization or the function of MAGI-1/BAP1 has not been clarified. In intestinal epithelial cells, MAGI-1/BAP1 was localized at tight junctions, whereas SAP97/hDLG was localized diffusely at cell - cell junctions. In Madine Darby canine kidney (MDCK) cells, MAGI-1/BAP1 was colocalized with ZO-1, whereas SAP97/hDLG was colocalized with E-cadherin. In MDCK cells, dominant active and negative mutants of Rac1 small G protein changed the amounts of SAP97/hDLG at cell - cell junctions, but not that of MAGI-1/BAP1. When MDCK cells were switched to a low Ca2+ medium, E-cadherin disappeared from the plasma membrane, and cells were dissociated. The phorbol 12-myristate 13-acetate-treatment after the low Ca2+ switch induced a tight junction-like structure. MAGI-1/BAP1 was recruited with ZO-1 to this structure, but SAP97/hDLG or E-cadherin was not. These findings suggest that MAGI-1/BAP1 is a component of tight junctions of epithelial cells, and that its role is different from that of SAP97/hDLG.

Adaptor Proteins, Signal Transducing↗
PubMed1999

Synamon, a novel neuronal protein interacting with synapse-associated protein 90/postsynaptic density-95-associated protein.

Guanylate kinase-associated protein (GKAP)/SAP90/PSD-95-associated protein (SAPAP)/DLG-associated protein (DAP) is a protein of the postsynaptic density (PSD), and binds to the guanylate kinase domain of PSD-95/synapse-associated protein (SAP) 90 and synaptic scaffolding molecule. GKAP/SAPAP/DAP recruits PSD-95/SAP90 and its interacting protein, brain-enriched guanylate kinase-interacting protein, into the Triton X-100-insoluble fraction in transfected cells, suggesting that GKAP/SAPAP/DAP may link several PSD components to the Triton X-100-insoluble structures in the PSD. We have identified here a novel neuronal GKAP/SAPAP/DAP-binding protein and named it synamon. Synamon has seven ankyrin repeats at the NH(2) terminus followed by one src homology 3 domain and one PSD-95/Dlg-A/ZO-1 domain, and several proline-rich regions at the carboxyl terminus. Synamon interacts with the COOH-terminal region of GKAP/SAPAP/DAP via the middle region containing a PSD-95/Dlg-A/ZO-1 domain. Synamon was coimmunoprecipitated with SAPAP from rat crude synaptosomes and colocalized with SAPAP in primary cultured rat hippocampal neurons. Because synamon is composed of various protein-interacting modules, it may also interact with proteins other than GKAP/SAPAP/DAP to organize the architecture of the PSD.

Adaptor Proteins, Signal Transducing↗
PubMed1999

Isolation and characterization of mammalian homologues of Caenorhabditis elegans lin-7: localization at cell-cell junctions.

In Caenorhabditis elegans, the vulval induction is mediated by the let-23 receptor tyrosine kinase (RTK)/ Ras signaling pathway. The precise localization of the let-23 RTK at the epithelial junctions is essential for the vulval induction, and requires three genes including lin-2, -7, and -10. The mammalian homologue of lin-2 has been identified as a protein interacting with a neuronal adhesion molecule, neurexin, and named CASK. CASK has recently been reported to interact with syndecans and an actin-binding protein, band 4.1, at epithelial and synaptic junctions, and to play central roles in the formation of cell-cell junctions. The product of C. elegans lin-7 directly interacts with let-23 RTK and localize it at epithelial junctions. Here, we report three rat homologues of lin-7 ubiquitously expressed in various tissues. These homologues are accumulated at the junctional complex region in cultured Madin-Darby canine kidney cells, and are also localized at the synaptic junctions in neurons. The mammalian homologues of lin-7 may be implicated in the formation of cell-cell junctions.

Amino Acid Sequence↗
PubMed1999

MAGUIN, a novel neuronal membrane-associated guanylate kinase-interacting protein.

Postsynaptic density (PSD)-95/Synapse-associated protein (SAP) 90 and synaptic scaffolding molecule (S-SCAM) are neuronal membrane-associated guanylate kinases. Because PSD-95/SAP90 and S-SCAM function as synaptic scaffolding proteins, identification of ligands for these proteins is important to elucidate the structure of synaptic junctions. Here, we report a novel protein interacting with the PDZ domains of PSD-95/SAP90 and S-SCAM and named it MAGUIN-1 (membrane-associated guanylate kinase-interacting protein-1). MAGUIN-1 has one sterile alpha motif, one PDZ, and one plekstrin homology domain. MAGUIN-1 is localized at the plasma membrane via the plekstrin homology domain and the C-terminal region and interacts with PSD-95/SAP90 and S-SCAM via a C-terminal PDZ domain-binding motif. MAGUIN-1 has a short isoform, MAGUIN-2, which lacks a PDZ domain-binding motif. MAGUINs are expressed in neurons and localized in the cell body and neurites and are coimmunoprecipitated with PSD-95/SAP90 and S-SCAM from rat crude synaptosome. MAGUIN-1 may play an important role with PSD-95/SAP90 and S-SCAM to assemble the components of synaptic junctions.

Adaptor Proteins, Signal Transducing↗
PubMed1999

Interaction of S-SCAM with neural plakophilin-related Armadillo-repeat protein/delta-catenin.

Synaptic scaffolding molecule (S-SCAM) is a multiple PDZ domain-containing protein, which interacts with neuroligin, a cell adhesion molecule, and the NMDA receptor. In this study, we searched for S-SCAM-interacting proteins and obtained a neuralplakophilin-related armadillo-repeat protein (NPRAP)/delta-catenin. NPRAP/delta-catenin bound to the last PDZ domain of S-SCAM via its carboxyl-terminus in three different cell-free assay systems, was coimmunoprecipitated with S-SCAM from rat crude synaptosomes, and was localized at the excitatory synapses in rat hippocampal neurons. NPRAP/delta-catenin may be implicated in the molecular organization of synaptic junctions through the interaction with S-SCAM.

Adaptor Proteins, Signal Transducing↗
PubMed1999

Involvement of the C-terminal region of yeast proteinase B inhibitor 2 in its inhibitory action.

Yeast proteinase B inhibitor 2 (YIB2), which is composed of 74 amino acid residues, is an unusual serine protease inhibitor, since it lacks disulfide bonds. To identify its reactive site for proteases, we constructed an expression system for a synthetic YIB2 gene and then attempted to change the inhibitory properties of YIB2 by amino acid replacements. The purified wild-type YIB2 inhibited the activity of subtilisin BPN', a protein homologous to yeast proteinase B, although its binding ability was not strong, and a time-dependent decrease in its inhibitory activity was observed, demonstrating that wild-type YIB2 behaves as a temporary inhibitor when subtilisin BPN' is the target protease. Since YIB2 exhibits sequence homology to the propeptide of subtilisin, which inhibits a cognate protease using its C-terminal region, we replaced the six C-termi nal residues of YIB2 with those of the propeptide of subtilisin BPN' to make the mutant YIB2m1. This mutant exhibited markedly increased inhibitory activity toward subtilisin BPN' without a time-dependent decrease in its inhibitory activity. Replacement of only the C-terminal Asn of YIB2 by Tyr, or deletion of the C-terminal Tyr of YIB2m1, inhibited subtilisin, but the ability of these mutants to bind subtilisin and their resistance to proteolytic attack were weaker than those of YIB2m1, indicating that the C-terminal residue contributes to the interaction with the protease to a greater extent than the preceding five residues and that the resistance of YIB2 to proteolyic attack is closely related to its ability to bind a protease. These results demonstrate that YIB2 is a unique protease inhibitor that involves its C-terminal region in the interaction with the protease.

Amino Acid Sequence↗
PubMed1999

Biomechanical comparison of spondylolysis fixation techniques.

STUDY DESIGN: A load-controlled biomechanical analysis of flexion, extension, and torsional stiffness in instrumented calf spines. OBJECTIVES: To compare biomechanically the performance of various fixation techniques for the repair of spondylolytic defects in the pars interarticularis. SUMMARY OF BACKGROUND DATA: Several techniques have been developed to stabilize a spondylolytic defect in the lumbar spine. There are, however, no comprehensive biomechanical studies in which these techniques are compared. METHODS: Nine fresh-frozen and thawed calf cadaveric lumbar L2-L6 spines were used for mechanical testing. Scott's technique, Buck's technique (screw fixation in the lamina across the defects), modified Scott's technique (wire loops around cortical screws placed into both pedicles and tightened under the spinous process), and screw-rod-hook fixation were applied on the calf lumbar spines in which bilateral spondylolytic defects were created in the L4 vertebra. Motion across the defects for each direction of loading in flexion, extension, and rotation was measured using extensometers. The intervertebral rotations and the strain at the site of the spondylolytic defect were computed from the acquired load-displacement data. RESULTS: Each fixation technique significantly increased stiffness and returned the intervertebral rotational stiffness to nearly intact levels. Displacement across the defect under flexion loading was significantly suppressed by each instrumentation technique, but the least motion (P < 0.05) was allowed with the screw-rod-hook fixation or Buck's technique. CONCLUSIONS: All four fixation techniques restored the intervertebral rotational displacements under flexion and torsional loading to the intact condition. The screw-rod-hook fixation allowed the least amount of motion across the defect during flexion.

Biomechanical Phenomena↗
PubMed1999

Resolution of bullous pemphigoid and improvement of vitiligo after successful treatment of squamous cell carcinoma of the skin.

The significance of the association of malignant diseases with bullous pemphigoid is still unknown. We report a case of squamous cell carcinoma of the skin associated with both bullous pemphigoid and vitiligo. It is possible that there is a common underlying pathogenic mechanism involved in the co-existence of these three skin diseases as successful treatment of the carcinoma was accompanied by resolution of the bullous pemphigoid and improvement of the vitiligo.

Aged↗
PubMed1999

Intermittent cisplatin therapy for stage-III ovarian cancer patients following clinical remission.

Intermittent cisplatin (CDDP) administration as consolidation therapy for stage-III ovarian cancer was studied. No patients with residual disease at surgery or at second-look operation or patients with <8 U/ml of CA125 after remission induction chemotherapy were enrolled in this study. Fifteen subjects received intermittent chemotherapy, and 10 control patients did not. CDDP of 20 mg/m2 for 5 days was administered every 3-4 months for 5 years. A significant increase in 5-year survival rate was found in the intermittent chemotherapy group when compared with the control group. Side effects from the intermittent chemotherapy were controllable. Intermittent CDDP therapy seems to be an effective consolidation therapy for stage-III ovarian cancer patients.

Antineoplastic Agents↗
PubMed1999

Elimination of anemia-inducing substance by cyclic plasma perfusion of tumor-bearing rabbits.

We carried out a fundamental study to search for a therapeutic modality that would remove the anemia-inducing substance (AIS) from the plasma of cancer patients because it is thought to be one of the substances responsible for anemia and immunodeficiency in advanced cancer patients. Using AIS isolated from the plasma of patients with advanced ovarian carcinoma, we confirmed that adsorption of AIS to noncoated charcoal was nonspecific and high. Moreover, it was verified that VX2 carcinoma-bearing rabbits are an optimal experimental model for plasma perfusion. The data obtained on day 40 after transplantation (hemoglobin, 9.1+/-2.1 g/dl; osmotic pressure inducing RBC lysis, 137+/-11 mosmol/kg; lymphocyte stimulation index, 8.8+/-8.6; and RBC fragility-inducing activity, 40+/-9 mosmol/kg) proved similar to the hematological findings in patients with cancer cachexia. A 1-h plasma perfusion (3 ml/min) through noncoated charcoal was performed in tumor-bearing rabbits, and it resulted in the restoration of RBC fragility-inducing activity and suppression of lymphocyte blast formation to pretransplantation values. When plasma perfusion was performed every 3 days, RBC fragility-inducing activity, which increased again 3 days after perfusion, was diminished, and RBC osmotic resistance was within the normal range from the fourth perfusion onward. These results showed that cyclic plasma perfusion is effective in sustained removal of RBC fragility-inducing factor from plasma, suggesting that it might have the potential for clinical application.

Adsorption↗
PubMed1998

BEGAIN (brain-enriched guanylate kinase-associated protein), a novel neuronal PSD-95/SAP90-binding protein.

PSD-95/SAP90 is a synaptic membrane-associated guanylate kinase with three PDZ, one SH3, and one guanylate kinase (GK) domain. PSD-95/SAP90 binds various proteins through the PDZ domains and organizes synaptic junctions. PSD-95/SAP90 also interacts with the postsynaptic density (PSD) fraction-enriched protein, named SAPAP (also called GKAP and DAP), through the GK domain. SAPAP is Triton X-100-insoluble and recruits PSD-95/SAP90 into the Triton X-100-insoluble fraction in the transfected cells, suggesting that SAPAP may fix PSD-95/SAP90 to the PSD. Here we report a novel protein interacting with the GK domain of PSD-95/SAP90, BEGAIN. BEGAIN is specifically expressed in brain and enriched in the PSD fraction. BEGAIN is Triton X-100-soluble in the transfected cells but is recruited to the Triton X-100-insoluble fraction by SAPAP when coexpressed with PSD-95/SAP90. BEGAIN may be a novel PSD component associated with the core complex of PSD-95/SAP90 and SAPAP.

Amino Acid Sequence↗
PubMed1998

A novel multiple PDZ domain-containing molecule interacting with N-methyl-D-aspartate receptors and neuronal cell adhesion proteins.

At synaptic junctions, pre- and postsynaptic membranes are connected by cell adhesion and have distinct structures for specialized functions. The presynaptic membranes have a machinery for fast neurotransmitter release, and the postsynaptic membranes have clusters of neurotransmitter receptors. The molecular mechanism of the assembly of synaptic junctions is not yet clear. Pioneering studies identified postsynaptic density (PSD)-95/SAP90 as a prototypic synaptic scaffolding protein to maintain the structure of synaptic junctions. PSD-95/SAP90 belongs to a family of membrane-associated guanylate kinases and binds N-methyl-D-aspartate receptors, potassium channels, and neuroligins through the PDZ domains and GKAP/SAPAP/DAP through the guanylate kinase (GK) domain. We performed here a yeast two-hybrid screening for SAPAP-interacting molecules and identified a novel protein that has an inverse structure of membrane-associated guanylate kinases with an NH2-terminal GK-like domain followed by two WW and five PDZ domains. It binds SAPAP through the GK-like domain and NMDA receptors and neuroligins through the PDZ domains. We named this protein S-SCAM (synaptic scaffolding molecule) because S-SCAM may assemble receptors and cell adhesion proteins at synaptic junctions.

Adaptor Proteins, Signal Transducing↗
PubMed1998

Biomechanical evaluation of translaminar facet joint fixation. A comparative study of poly-L-lactide pins, screws, and pedicle fixation.

STUDY DESIGN: Nine sheep cadaveric spines were used in this acute postoperative model. OBJECTIVES: To compare the biomechanical performance of translaminar facet joint fixation techique with that of cortical screws and bioabsorbable poly-L-lactide pins and with that of rigid pedicle screw fixation in the lumbar spine. SUMMARY OF BACKGROUND DATA: Among numerous posterior spine fixation techniques, pedicle screw fixation has been reported to be the most rigid construct and to provide high fusion rate. Translaminar facet joint screw fixation is an alternative to pedicle screw fixation and is the lowest profile construct that achieves stabilization. The authors have developed a new concept involving application of bioabsorbable poly-L-lactide pins to translaminar facet joint fixation. Degradation in the stiffness of the implants with time may be advantageous for fusion mass remodeling. METHODS: A total of nine sheep L2-L6 cadaveric spines were used. Each intact spine was nondestructively tested in flexion-extension bending (+/- 5-Nm peak bending moment with 100-N axial compression) on a modified testing machine. Loads were applied for 10-second periods using sinusoid waveforms. After testing the intact spine, bilateral fenestration was performed between L4 and L5 and the medial aspect of the facet capsule was resected. The L4-L5 functional spinal unit was than stabilized by five methods: translaminar facet joint fixation with smooth poly-L-lactide pins; translaminar facet joint fixation with cortical screws; pedicle screw fixation with the Texas Scottish Rite Hospital system; and without instrumentation, in that order. Linear displacement of L4 inferior and L5 superior articular processes in the sagittal plain (delta facet) and L4-L5 intervertebral rotation in the sagittal plain (theta sagittal) were measured by the extensometers mounted to the spine. Ranges of motion (delta facet and theta sagittal), neutral zones, linear elastic zone stiffness, and the total energy absorption during the load-unload cycle (hysteresis) were calculated. RESULTS: By resecting the facet joint capsules and ligamentum flavum, delta facet and theta sagittal were not increased significantly, whereas the increase of neutral zones and hysteresis were statistically significant. Compared with the intact spine, delta facet was significantly reduced to 41% of normal with translaminar facet joint fixation with poly-L-lactide pins, to 9% with translaminar facet joint fixation with screws, and to 11% with the Texas Scottish Rite Hospital system. Neutral zones of delta facet showed a similar pattern, and these differences were significant. Regarding linear elastic zone stiffness, translaminar facet joint fixation with screws provided a stiffer construct than did pedicle screw fixation in the flexion loading mode, whereas pedicle screw fixation yielded higher values for stiffness in extension loading. Translaminar facet joint fixation with poly-L-lactide pins increased linear elastic zone stiffness in extension loading, but the increase was less than was achieved with the other constructs. CONCLUSIONS: The facet joint is the only true articulation in the lumbosacral spine. It is logical to fix this part directly to achieve spine fixation. Translaminar facet joint fixation with screws show similar biomechanical performance to pedicle screw fixation. Translaminar facet joint fixation with poly-L-lactide pins is significantly less stiff than either type of screw fixation, but it also restricts the facet joint and intervertebral motions significantly when compared with the intact spine.

Analysis of Variance↗