PubMed Health⌕ Search

Biomedical subjects

Hiroki Mori

Publications and source records attributed to Hiroki Mori.

At least 19 recordsLinked to original sources
PubMed2007

Monoclonal antibody 7F9 recognizes rat protein homologous to human carboxypeptidase-M in developing and adult rat lung.

BACKGROUND AND OBJECTIVE: The purpose of this study was to obtain an antibody that would be useful for investigating the yet unclear molecular mechanism underlying the differentiation of lung alveolar type I and II cells. METHODS: Monoclonal antibodies were raised against membrane proteins from embryonal day 18.5 rat lungs and characterized by immunoblotting on rat lung lysates at various developmental stages to select an appropriate clone. The antigen of the selected antibody was purified by serial column chromatography and immunoprecipitation and identified by mass spectrometry. RESULTS: 7F9 antibody recognizes a 65-kDa protein that is expressed most prominently from embryonal day 20.5 to postnatal day 1. This protein was identified as a rat protein that is similar to 5730456K23Rik protein. The protein is homologous to human carboxypeptidase-M. Although human carboxypeptidase-M is known as a marker of type I cells, the expression of this rat protein was detected in columnar epithelial cells expressing type II cell markers, SP-C and a lamellar body protein ABCA3, in developing lung. Its expression was detected in alveolar cells lacking T1alpha, a type I cell marker protein, in adult lung. It was also expressed in RLE-6TN cells derived from type II cells. The expression in RLE-6TN cells was down-regulated by transforming growth factor-beta1 and up-regulated by Wnt3a. CONCLUSIONS: 7F9 antibody detects a protein in rat lung cells expressing type II markers. The antibody is a useful tool for studying signalling triggered by transforming growth factor-beta1 and Wnt3a in rat type II cells.

Animals↗
PubMed2006

Quality control of photosystem II. Cleavage of reaction center D1 protein in spinach thylakoids by FtsH protease under moderate heat stress.

When spinach thylakoids were subjected to moderate heat stress (40 degrees C for 30 min), oxygen evolution was inhibited, and cleavage of the reaction center-binding protein D1 of photosystem II took place, producing 23-kDa N-terminal fragments. The D1 cleavage was greatly facilitated by the addition of 0.15 mM ZnCl2 and 1 mM ATP and was completely inhibited by 1 mM EDTA, indicating the participation of an ATP-dependent metalloprotease(s) in the D1 cleavage. Herbicides 3-(3,4-dichlorophenyl)-1,1-dimethyl urea, bromoxynil, and ioxynil, all of which bind to the Q(B) site, inhibited the D1 cleavage, suggesting that the DE-loop of the D1 protein is the heat-sensitive cleavage site. We solubilized the protease by treating the thylakoids with 2 M KSCN and detected a protease activity in the supernatant by gelatin activity gel electrophoresis in the 70-80-kDa region. The antibodies against tobacco FtsH and Arabidopsis FtsH2 reacted with a 70-80-kDa band of the KSCN-solubilized fraction, which suggests the presence of FtsH in the fraction. In accordance with this finding, we identified the homolog to Arabidopsis FtsH8 in the 70-80-kDa region by matrix-assisted laser desorption ionization time-of-flight mass analysis of the thylakoids. The KSCN-solubilized fraction was successively reconstituted with thylakoids to show heat-induced cleavage of the D1 protein and production of the D1 fragment. These results strongly suggest that an FtsH protease(s) is involved in the primary cleavage of the D1 protein under moderate heat stress.

ATP-Dependent Proteases↗
PubMed2006

Isomerization reaction of head-to-head alpha-pyridonato-bridged ethylenediaminepalladium(II) binuclear complex, [Pd2(en)2(C5H4NO)2]2+, in aqueous solution.

Head-to-head bis(alpha-pyridonato)-bridged bis(ethylenediamine)dipalladium(ii), HH-[Pd(2)(en)(2)(alpha-pyridonato)(2)](ClO(4))(2), was synthesized and structurally characterized by X-ray crystallography. The (1)H NMR spectra show that the head-to-head (HH) dimer produces the head-to-tail (HT) dimer and monomers ([Pd(en)(alpha-pyridone)(2)](2+), [Pd(en)(H(2)O)(alpha-pyridone)](2+), [Pd(en)(H(2)O)(2)](2+), etc.) in aqueous solution, and the relative amount of dimers to monomers is dependent on the total concentration of the HH dimer dissolved as well as the acidity of the solution. It was found that the formation of the HH and HT dimers from the monomers is fast, and the HT dimer is produced from the HH dimer only via coexisting monomers, i.e., there is no direct isomerization path between the HH and HT dimers. The kinetic analyses for the HH <==>HT isomerization reaction with time-resolved (1)H NMR measurements revealed that the reaction proceeds via first-order kinetics, which was explained based on a relaxation process. The rate determining step for HH <==>HT isomerization is the reaction step between the mono-alpha-pyridone complex and the bis-alpha-pyridone complex, [Pd(en)(H(2)O)(alpha-pyridone)](2+)+alpha-pyridone <==> [Pd(en)(alpha-pyridone)(2)](2+).

Crystallography, X-Ray↗
PubMed2006

CIN85 is localized at synapses and forms a complex with S-SCAM via dendrin.

Membrane-associated guanylate kinase inverted (MAGI)-1 plays a role as a scaffold at cell junctions in non-neuronal cells, while S-SCAM, its neuronal isoform, is involved in the organization of synapses. A search for MAGI-1-interacting proteins by yeast two-hybrid screening of a kidney cDNA library yielded dendrin. As dendrin was originally reported as a brain-specific postsynaptic protein, we tested the interaction between dendrin and S-SCAM and revealed that dendrin binds to the WW domains of S-SCAM. Dendrin is known to be dendritically translated but its function is largely unknown. To gain insights into the physiological meaning of the interaction, we performed a second yeast two-hybrid screening using dendrin as a bait. We identified CIN85, an endocytic scaffold protein, as a putative dendrin-interactor. Immunocytochemistry and subcellular fractionation analysis supported the synaptic localization of CIN85. The first SH3 domain and the C-terminal region of CIN85 bind to the proline-rich region and the N-terminal region of dendrin, respectively. In vitro experiments suggest that dendrin forms a ternary complex with CIN85 and S-SCAM and that this complex formation facilitates the recruitment of dendrin and S-SCAM to vesicle-like structures where CIN85 is accumulated.

Adaptor Proteins, Signal Transducing↗
PubMed2005

Oligomers of Tha4 organize at the thylakoid Tat translocase during protein transport.

The Tat (twin arginine translocation) systems of thylakoids and bacteria transport fully folded protein substrates without breaching the permeability barrier of the membrane. Two components of the thylakoid system, cpTatC and Hcf106, compose a precursor-bound receptor complex. The third component, Tha4, assembles with the precursor-bound receptor complex for the translocation step and is thought to compose at least part of the protein-conducting channel. Here, we used two different cross-linking approaches to explore the organization of Tha4 in the translocase. These cross-linking techniques showed that transition to an active protein transport state resulted in an alignment of the Tha4 amphipathic helix and C-terminal tail domains to form Tha4 oligomers. Oligomerization required functional Tha4, a twin arginine signal peptide, and an active cpTatC-Hcf106 receptor complex. The spectrum of oligomers obtained was independent of the mature folded domain of the precursor. We propose a trapdoor mechanism for translocation whereby aligned oligomers of Tha4 amphipathic helices fold into the membrane to allow formfitting passage of precursor proteins.

Amino Acid Sequence↗
PubMed2005

MAGI-1 is a component of the glomerular slit diaphragm that is tightly associated with nephrin.

MAGUK with inverted domain structure-1 (MAGI-1) is a membrane-associated protein with one guanylate kinase, six PSD-95/Dlg-A/ZO-1 (PDZ), and two WW domains and is localized at tight junctions in epithelial cells. MAGI-1 interacts with various proteins and is proposed to function as a scaffold protein. In the previous study, we discovered a MAGI-1-interacting cell adhesion molecule junctional adhesion molecule 4 (JAM4). Both proteins are highly expressed in glomerular podocytes in the kidney and partially colocalized. In this study, we have further searched for a binding partner of MAGI-1 in the kidney through yeast two-hybrid screening and obtained nephrin. Nephrin is a cell adhesion molecule specifically localized at the slit diaphragm between neighboring foot processes of podocytes. Biochemical studies reveal that nephrin directly binds to the middle PDZ domains of MAGI-1 through its carboxyl terminus but does not bind to ZO-1. MAGI-1 forms a tripartite complex with nephrin and JAM4 in vitro. Immunoelectron microscopy shows that the localization of MAGI-1 is restricted to the slit diaphragm, whereas JAM4 is also distributed on apical membranes of podocytes. In puromycin aminonucleoside-induced nephrotic podocytes, MAGI-1 is localized with nephrin at the displaced slit diaphragm. These data indicate that MAGI-1 is a component of the slit diaphragm and tightly interacts with nephrin and JAM4 in vivo. MAGI-1 may play a role in determining the boundary between the apical and the bosolateral domain at the level of slit diaphragm.

Adaptor Proteins, Signal Transducing↗
PubMed2005

Balloon occluded retrograde transvenous obliteration and percutaneous transhepatic obliteration for ruptured duodenal varices after operation for rectal cancer with multiple liver metastasis: report of a case.

We report a patient with duodenal varices oozing blood who had undergone low anterior resection of the rectum and resection of the liver tumor because of multiple liver metastasis from rectal cancer 80 months previously. Although endoscopic variceal ligation (EVL) was carried out for the ruptured duodenal varices, their bleeding persisted and hepatic encephalopathy also appeared. Finally, balloon occluded retrograde transvenous obliteration (BRTO) with percutaneous transhepatic obliteration (PTO) was carried out for the duodenal varices. Percutaneous transhepatic portography revealed detailed hemodynamics. Following PTO, the duodenal varices were stagnated by BRTO, and no complications were recognized. No re-bleeding episode has been observed since the treatment. In addition, the hepatic encephalopathy was also improved.

Adult↗
PubMed2005

Esthetic evaluation of immediate breast reconstruction after nipple-sparing or skin-sparing mastectomy.

BACKGROUND: It has been reported that immediate autologous tissue breast reconstruction after nipple-sparing mastectomy (NSM) or skin-sparing mastectomy (SSM) is esthetically superior to autologous tissue reconstruction after conventional mastectomy (CM). We evaluated reconstructed breasts to determine whether these methods contribute to breast appearance other than skin texture. METHODS: Between April 1992 and September 2001, forty-two patients underwent immediate breast reconstruction using autologous tissue. Mastectomy options were NSM, SSM and CM. Postoperative photographs were evaluated using a subscale (volume, contour, placement, and inframammary fold) on a 0-2 point scale. Sternal notch to nipple distances of the affected and normal sides were measured with photographs to estimate nipple-areola complex (NAC) position. No corrective procedure was performed in a later phase before evaluation. RESULTS: NSM was performed in 22, SSM in 6 and CM in 14 cases. On esthetic evaluation, the NSM and SSM groups received 4.96 and the CM group received 4.63. There were no significant differences. In the NSM and SSM group, the NAC position rose in cases with partial necrosis or fat lysis compared with the no complication group (p = 0,004). CONCLUSIONS: Autologous tissue breast reconstruction after NSM or SSM is esthetically equal to autologous tissue reconstruction after CM with regard to parameters other than skin texture. Preserved or simultaneously reconstructed NAC sometimes emphasizes nipple-areola asymmetry when breast deformity has occurred.

Adult↗
PubMed2005

[Treatment of recurred HCV infection after liver transplantation].

Prognosis of recurred HCV recipient after both deceased and live liver transplantation is quite worse in foreign countries, recently. The reason of this poor prognosis is believed as immune-suppressant, steroid bolus, aged donor and liver donor in USA and Europe. However, in Japan, survival ration of HCV recipients is 5% reduction than mean survival of live donor liver transplantation. In addition, post transplant treatment of recurred HCV recipient is not good result in out of Japan, because of high rate of withdraw or drop out with peg interferon and ribavirin. On the contrary, some of Japanese investigator reported with 40-50% SVR with same drug management. It is still controversy whether HCV recipients are poor prognosis after transplantation and treatment resistance.

Hepatitis C↗
PubMed2004

JAM4 enhances hepatocyte growth factor-mediated branching and scattering of Madin-Darby canine kidney cells.

Junctional adhesion molecule (JAM) 4 is a member of immunoglobulin superfamily that interacts with MAGI-1, a membrane-associated guanylate kinase protein at tight junctions in epithelial cells. We prepared Madin-Darby canine kidney II (MDCK) cells expressing JAM4 (MDCK-JAM4) and compared them with wild MDCK cells. The treatment of hepatocyte growth factor (HGF) induced more prominent branching and scattering in MDCK-JAM4 cells. Subsequently we attempted to identify signalling pathways modified by JAM4. The over-expression of JAM4 induced the formation of protrusions in COS-7 cells. Although those protrusions were different from typical lamellipodia, the dominant negative mutant of Rac suppressed them. The pull-down assay using CDC42 and Rac interactive binding domain of PAK also supports that Rac is activated in COS-7 cells expressing JAM4. Taken together, JAM4 itself activates Rac and may augment Rac activation by HGF, resulting in the enhancement of branching and scattering.

Animals↗
PubMed2003

Functional interaction of chloroplast SRP/FtsY with the ALB3 translocase in thylakoids: substrate not required.

Integration of thylakoid proteins by the chloroplast signal recognition particle (cpSRP) posttranslational transport pathway requires the cpSRP, an SRP receptor homologue (cpFtsY), and the membrane protein ALB3. Similarly, Escherichia coli uses an SRP and FtsY to cotranslationally target membrane proteins to the SecYEG translocase, which contains an ALB3 homologue, YidC. In neither system are the interactions between soluble and membrane components well understood. We show that complexes containing cpSRP, cpFtsY, and ALB3 can be precipitated using affinity tags on cpSRP or cpFtsY. Stabilization of this complex with GMP-PNP specifically blocks subsequent integration of substrate (light harvesting chl a/b-binding protein [LHCP]), indicating that the complex occupies functional ALB3 translocation sites. Surprisingly, neither substrate nor cpSRP43, a component of cpSRP, was necessary to form a complex with ALB3. Complexes also contained cpSecY, but its removal did not inhibit ALB3 function. Furthermore, antibody bound to ALB3 prevented ALB3 association with cpSRP and cpFtsY and inhibited LHCP integration suggesting that a complex containing cpSRP, cpFtsY, and ALB3 must form for proper LHCP integration.

Arabidopsis↗
PubMed2003

Requirement of a Tha4-conserved transmembrane glutamate in thylakoid Tat translocase assembly revealed by biochemical complementation.

The thylakoid Tat system employs three membrane components and the pH gradient to transport folded proteins. The translocase is signal-assembled, i.e. a receptor complex containing cpTatC and Hcf106 binds the precursor protein, and upon membrane energization, Tha4 is recruited to the precursor-receptor complex to effect translocation. We developed a two-step complementation assay to examine the implied central role of Tha4 in translocation. The first step results in the inactivation of endogenous Tha4 with specific antibodies. The second step involves integrating exogenous Tha4 and presenting the system with precursor protein. We verified this approach by confirming the results obtained recently with the Escherichia coli Tha4 ortholog TatA, i.e. that the carboxyl terminus is dispensable and the amphipathic helix essential for transport. We then investigated a conserved Tha4 transmembrane glutamate in detail. Substitution of glutamate 10 with alanine, glutamine, and even aspartate largely eliminated the ability of Tha4 to complement transport, whereas a conservative substitution elsewhere in the transmembrane domain was without effect. Chemical cross-linking assays showed that the mutated Tha4s failed to be recruited to the receptor complex under transport conditions, indicating a role for the transmembrane glutamate in translocase assembly. This assay promises an avenue into understanding the role of Tha4 in both the assembly and translocation steps of the Tat translocase.

Alanine↗
PubMed2003

Preparation and magnetic properties of Mn(hfac)(2)-complexes of 2-(5-pyrimidinyl)- and 2-(3-pyridyl)-substituted nitronyl nitroxides.

Mn(hfac)(2) complexes of [2-(5-pyrimidinyl)-4,4,5,5-tetramethyl-4,5-dihydro-1H- imidazoline-1-oxyl 3-oxide] (1) and its 2-(3-pyridyl) analogue (2) were prepared. Both complexes formed similar dimer structures. However, their packing patterns were considerably different. The pyrimidine dimers were aligned to form a linear chain structure, and each dimer was weakly bound by two sets of O6-C2 short contacts. In the pyridine dimer complex, two structurally similar but independent dimers were alternatively arranged, and two dimer-dimer contacts, O6-C2 (3.13 A) and O6-C3 (3.30 A), were observed. The pyrimidine complex showed strong antiferromagnetic behavior in the high temperature region (150-300 K) and weak ferromagnetic behavior below 100 K. Two models were used to analyze these magnetic properties. One is a quintet-septet thermal equilibrium model with mean-field approximation, which can reproduce the round minimum observed at about 150 K in chi(p)T plots (J(1)/k(B) = -148 +/- 2 K with theta = +2.5 +/- 0.1 K). The other is a ferromagnetic S = 2 chain model to fit the chi(p)T values in the lower temperature region (J(S=2)/k(B) = +0.31 +/- 0.01 K). The pyridine complex showed antiferromagnetic interactions both in the high and low temperature regions. The magnetic behavior was similarly analyzed with the following parameters: J(1)/k(B) = -140 +/- 2 K with theta = -0.55 +/- 0.05 K, and J(S=2)/k(B) = -0.075 +/- 0.003 K. The ligand-ligand interactions for both of the complexes were theoretically analyzed. The calculated results agreed well with the experiments. The stronger antiferromagnetic behavior observed in both the complexes at high temperatures was attributed to the magnetic interaction between the Mn(II) and the coordinating nitroxide oxygen atom. The weaker ferromagnetic interaction, J(S=2)/k(B) = +0.31 +/- 0.01 K, in the pyrimidine complex was attributed to the coulombic O6-C2 contact. Antiferromagnetic interaction J(S=2)/k(B) = -0.075 +/- 0.003 K in the pyridine complex was attributed to the O6-C3 contact.

Journal Article↗
PubMed2003

JAM4, a junctional cell adhesion molecule interacting with a tight junction protein, MAGI-1.

MAGI-1 is a membrane-associated guanylate kinase protein at tight junctions in epithelial cells. It interacts with various molecules and functions as a scaffold protein at cell junctions. We report here a novel MAGI-1-binding protein that we named junctional adhesion molecule 4 (JAM4). JAM4 belongs to an immunoglobulin protein family. JAM4 was colocalized with ZO-1 in kidney glomeruli and in intestinal epithelial cells. Biochemical in vitro studies revealed that JAM4 bound to MAGI-1 but not to ZO-1, whereas JAM1 did not bind to MAGI-1. JAM4 and MAGI-1 interacted with each other and formed clusters in COS-7 cells when coexpressed. JAM4 mediated calcium-independent homophilic adhesion and was accumulated at cell-cell contacts when expressed in L cells. MAGI-1, ZO-1, and occludin were recruited to JAM4-based cell contacts. JAM4 also reduced the permeability of CHO cell monolayers. MAGI-1 strengthened JAM4-mediated cell adhesion in L cells and sealing effects in CHO cells. These findings suggest that JAM4 together with MAGI-1 provides an adhesion machinery at tight junctions, which may regulate the permeability of kidney glomerulus and small intestinal epithelial cells.

Adenoviridae↗
PubMed2003

Ultrasonic tissue characterization of the atherosclerotic carotid artery: histological correlates or carotid integrated backscatter.

Histological abnormalities of the atherosclerotic lesion are closely related to the stability of the plaque. Specifically, the plaque is likely to be unstable if the fibrous cap is thin. However, ultrasonic characterization of the atherosclerotic lesion has not been done from this viewpoint. Thus, in the present study ultrasonic tissue characterization of the carotid atherosclerotic lesion was attempted to assess the stability of the plaque. Integrated ultrasonic backscatter (IBS) in the atherosclerotic lesion was compared with histological findings of the respective tissue in 35 patients with carotid artery stenosis who underwent carotid endarterectomy. Carotid IBS was determined by locating the region-of-interest (ROI) in the center of the atherosclerotic lesion and calibrating by subtracting the IBS in the tunica externa of the vessel from the IBS of the ROI. IBS was also determined at the interface of the plaque, and at this site it was analyzed in relation to the thickness of the fibrous cap. Lipid content, fibrous tissue, thrombus, hemorrhage and calcification were histologically assessed in the respective tissue. Carotid IBS in the lipid lesion (-22.5+/-4.1 dB) was significantly different from that of fibrous, hemorrhagic or calcified lesions (-11.1+/-7.1, -27.5+/-4.1, +2.1+/-6.5 dB, respectively), but there was no significant difference in IBS between the lipid lesion and thrombus (-15.2+/-8.8 dB). IBS was lower in the thin fibrous cap than in the thick lesion (-10.9+/-6.4 vs -2.4+/-6.2 dB, p<0.001). IBS can be used to characterize atherosclerotic lesions in the carotid artery; a low value at the interface suggests a thin fibrous cap, which is frequently associated with unstable plaque.

Adult↗
PubMed2002

A twin arginine signal peptide and the pH gradient trigger reversible assembly of the thylakoid [Delta]pH/Tat translocase.

The thylakoid DeltapH-dependent/Tat pathway is a novel system with the remarkable ability to transport tightly folded precursor proteins using a transmembrane DeltapH as the sole energy source. Three known components of the transport machinery exist in two distinct subcomplexes. A cpTatC-Hcf106 complex serves as precursor receptor and a Tha4 complex is required after precursor recognition. Here we report that Tha4 assembles with cpTatC-Hcf106 during the translocation step. Interactions among components were examined by chemical cross-linking of intact thylakoids followed by immunoprecipitation and immunoblotting. cpTatC and Hcf106 were consistently associated under all conditions tested. In contrast, Tha4 was only associated with cpTatC and Hcf106 in the presence of a functional precursor and the DeltapH. Interestingly, a synthetic signal peptide could replace intact precursor in triggering assembly. The association of all three components was transient and dissipated upon the completion of protein translocation. Such an assembly-disassembly cycle could explain how the DeltapH/Tat system can assemble translocases to accommodate folded proteins of varied size. It also explains in part how the system can exist in the membrane without compromising its ion and proton permeability barrier.

Arginine↗
PubMed2002

Isolation of a diterpenoid substance with potent neuroprotective activity from fetal calf serum.

Excess activation of glutamate receptors and production of free radicals including nitric oxide may result in severe and irreversible damage to the mammalian central nervous system (CNS), but endogenous defense systems that protect neurons from these insults are poorly understood. Here, we purified and isolated a neuroprotective substance, which has been named "serofendic acid," from a lipophilic fraction of FCS based on the ability to protect rat primary cortical neurons against nitric oxide cytotoxicity. Mass spectrometry and NMR spectroscopy revealed the chemical structure of serofendic acid (15-hydroxy-17-methylsulfinylatisan-19-oic acid) as a sulfur-containing atisane-type diterpenoid, which is unique among known endogenous substances. Synthetic serofendic acid exhibited potent protective actions on cortical neurons against cytotoxicity of a nitric oxide donor as well as of glutamate, although it did not show appreciable influences on glutamate receptor-mediated responses in these neurons. Electron spin resonance analysis demonstrated that serofendic acid had no direct scavenging activity on nitric oxide radicals but was capable of inhibiting the generation of hydroxyl radical, a presumed "executor" radical in the nitric oxide-mediated neurotoxic cascade. These findings suggest that serofendic acid is a low-molecular-weight bioactive factor that promotes survival of CNS neurons, probably through the attenuation of free radical-mediated insults.

Animals↗