Biomedical subjects

Yuji Tanaka

Publications and source records attributed to Yuji Tanaka.

At least 37 records · Page 2Linked to original sources

PubMed2005

Up-regulation of Mrp4 expression in kidney of Mrp2-deficient TR- rats.

Multidrug resistance-associated proteins (Mrps) are a group of ATP-dependent efflux transporters for organic anions. Mrp2 and Mrp4 are co-localized to the apical (brush-border) membrane domain of renal proximal tubules, where they may function together in the urinary excretion of organic anions. Previous reports showed that urinary excretion of some organic anions is not impaired in transport-deficient (TR-) rats, which lack Mrp2, suggesting that up-regulation of other transporter(s) may compensate for the loss of Mrp2 function. The purpose of this study was to determine whether Mrp4 expression in kidney is altered in TR- rats. Mrp4 mRNA expression was quantified using the high-throughput branched DNA signal amplification assay. Mrp4 protein expression was determined by Western blot and immunohistochemical analysis. Mrp4 mRNA in kidney of TR- rats was 100% higher than normal Wistar rats. Western blot analysis showed a 200% increase in Mrp4 protein expression in kidney of the mutant rats compared to normal rats. Immunohistochemical analysis of Mrp4 protein demonstrated apical localization of Mrp4 on renal proximal tubules, and that the immunoreactivity was more intense in kidney sections from TR- rats than those from normal rats. In summary, the results of the present study demonstrate that renal Mrp4 expression is up-regulated in TR- rats, which may explain why urinary excretion of some organic anions remains normal in the mutant rats.

Animals↗

PubMed2005

Progressive phenotype and nuclear accumulation of an amino-terminal cleavage fragment in a transgenic mouse model with inducible expression of full-length mutant huntingtin.

Huntington's disease (HD) is an autosomal dominant neurodegenerative disorder characterized behaviorally by chorea, incoordination, and shortened lifespan and neuropathologically by huntingtin inclusions and neuronal degeneration. In order to facilitate studies of pathogenesis and therapeutics, we have generated a new inducible mouse model of HD expressing full-length huntingtin (Htt) using a tetracycline-regulated promoter. In double transgenic mice Htt was expressed widely in the brain under the control of the tet-transactivator (tTA) driven by the prion promoter PrP (in the absence of doxycycline). Mice expressing full-length mutant Htt, but not full-length normal Htt, displayed a progressive behavioral phenotype, consisting of slowed and irregular voluntary movements, gait ataxia, tremor and jerky movements, incoordination, and weight loss, with a shortened lifespan. Neuropathology included prominent intranuclear inclusions in cortex and striatum as well as cytoplasmic aggregates. This phenotype is very similar to the phenotypes of previous transgenic mice expressing N-terminal fragments of mutant Htt. The current HD-transgenic mice had nuclear accumulation of Htt, particularly an approximately 60-kDa fragment, which appears to represent an N-terminal cleavage product. This fragment is smaller than calpain or caspase-derived cleavage products of Htt, but it is comparable to a product, termed cp-A, which accumulates in nuclei of cells in a previously described cell model. This new mouse model may be useful in the future for pathogenic and preclinical therapeutic studies related to HD. The data suggest that proteolytic processing could be a part of the pathogenesis of HD, potentially representing an attractive therapeutic target.

Animals↗

PubMed2005

The ZDHHC8 gene did not associate with bipolar disorder or schizophrenia.

The zinc finger and DHHC domain-containing protein 8 (ZDHHC8) gene is located on chromosome 22q11, which several genome scans have provided repeated evidence for a significant linkage with bipolar disorder (BPD) and schizophrenia. A recent study revealed that a single nucleotide polymorphism (SNP), rs175174, which has potential effects on splicing, in intron 4 of the ZDHHC8 gene is associated with susceptibility to patients with schizophrenia in US and South Africa. We examined three SNPs of the ZDHHC8 gene, including rs175174, by case-control association in Japanese patients with BPD (N=172) and controls (N=298) or patients with schizophrenia (N=407) and controls (N=497). No significant association with BPD or schizophrenia was observed. After stratification by subcategories, bipolar I and II of BPD, and paranoid and disorganized types of schizophrenia, no significant association was found, nor was a significant association with either disorder found after dividing by gender. These data suggest that the ZDHHC8 gene may not be associated with susceptibility to BPD or schizophrenia, at least in a Japanese population.

Acyltransferases↗

PubMed2005

Betacellulin-delta4, a novel differentiation factor for pancreatic beta-cells, ameliorates glucose intolerance in streptozotocin-treated rats.

We previously described a novel alternatively spliced mRNA transcript of the betacellulin (BTC) gene. This splice isoform, termed BTC-delta4, lacks the C-loop of the epidermal growth factor motif and the transmembrane domain as a result of exon 4 'skipping'. In this study, we expressed BTC-delta4 recombinantly to explore its biological function. When BTC-delta4 was expressed in COS-7 cells, it was secreted largely into the culture medium, in contrast to BTC. Unlike BTC, highly purified recombinant BTC-delta4 produced in Escherichia coli failed to bind or induce tyrosine phosphorylation of either ErbB1 or ErbB4, nor did it antagonize the binding of BTC to these receptors. Consistent with this, BTC-delta4 failed to stimulate DNA synthesis in Balb/c 3T3 and INS-1 cells. However, BTC-delta4 induced differentiation of pancreatic beta-cells; BTC-delta4 converted AR42J cells to insulin-producing cells. When recombinant BTC-delta4 was administered to streptozotocin-treated neonatal rats, it reduced the plasma glucose concentration and improved glucose tolerance. Importantly, BTC-delta4 significantly increased the insulin content, the beta-cell mass, and the numbers of islet-like cell clusters and PDX-1-positive ductal cells. Thus, BTC-delta4 is a secreted protein that stimulates differentiation of beta-cells in vitro and in vivo in an apparent ErbB1- and ErbB4-independent manner. The mechanism by which BTC-delta4 exerts this action on beta-cells remains to be defined but presumably involves an, as yet, unidentified unique receptor.

Animals↗

PubMed2005

Early immune reaction after reduced-intensity cord-blood transplantation for adult patients.

BACKGROUND: To investigate immune reactions after reduced-intensity cord-blood transplantation (RI-CBT). MATERIALS AND METHODS: We reviewed medical records of 57 adult RI-CBT recipients. Preparative regimen comprised fludarabine, total-body irradiation, and either melphalan (n=51) or busulfan (n=6). Graft-versus-host disease (GvHD) prophylaxis was cyclosporine. PostRI-CBT immune reactions were classified according to time course: pre-engraftment immune reactions (PIR), engraftment syndrome (ES), and GvHD. RESULTS: Forty-five patients achieved engraftment at a median of day 19. PIR was characterized by high-grade fever and weight gain and developed on a median of day 9 in 35 of the 45 evaluable patients, including 3 who did not achieve engraftment. PIR subsided spontaneously in 12 patients, whereas corticosteroids were required in the other 23. ES and grade I to IV acute GvHD developed in 36 and 29 patients, respectively. GvHD could not be distinguished from preceding PIR or ES in 10 patients. Causes of the 32 nonrelapse mortalities included GvHD (n=5) and PIR (n=1). There were no significant differences in relapse and nonrelapse deaths between patients with PIR and those without it (18% vs. 5%, and 60% vs. 65%, respectively). CONCLUSIONS: Immune reactions after RI-CBT can be categorized into three distinct subtypes.

Adult↗

PubMed2005

Localization of soluble beta-carbonic anhydrase in the marine diatom Phaeodactylum tricornutum. Sorting to the chloroplast and cluster formation on the girdle lamellae.

A beta-carbonic anhydrase (CA) in the marine diatom Phaeodactylum tricornutum (PtCA1) is encoded by the nuclear genome. This enzyme was previously found to be important for the operation of photosynthesis with a high affinity for dissolved inorganic carbon. A cDNA sequence that encodes PtCA1 (ptca1) was shown to possess a presequence of 138 bp (pre138), which encodes an N-terminal sequence of 46 amino acids (Pre46AA) that does not exist in the mature PtCA1. In this study, pre138 was ligated with the enhanced green fluorescent protein (GFP) gene (egfp), and introduced into P. tricornutum by microprojectile bombardment. Subsequently, the expressed Pre46AA-GFP fusion was shown to be localized in the chloroplast stroma, whereas the expressed GFP without Pre46AA was localized in the cytoplasm. Insertion of the DNA sequence, encoding a mature region of ptca1 (mptca1) between pre138 and egfp, resulted in the formation of particles with concentrated GFP fluorescence in the stroma of P. tricornutum. These particles, 0.3 to 3.0 mum in size, were shown to be distinct from the mitochondria and localized on the surface of the putative girdle lamella. The attachment of the initial one-half of the pre138 to the mptca1-egfp fusion caused the expressed GFP fusion to accumulate in areas surrounding the chloroplast, presumably due to the presence of the endoplasmic reticulum signal encoded by the initial half-sequence and to the absence of the chloroplast transit sequence. These results indicate that PtCA1 is targeted to the stroma by the bipartite sequences of Pre46AA and that the observed GFP particles are formed specifically in the stroma due to the function of the mptca1.

Amino Acid Sequence↗

PubMed2005

The X-box binding protein 1 (XBP1) gene is not associated with methamphetamine dependence.

Bipolar disorder has known as a high risk factor for substance abuse and dependence such as alcohol and illegal drugs. Recently, Kakiuchi et al. reported that the -116C/G polymorphism in the promoter region of the X-box binding protein 1 (XBP-1) gene, which translates a transcription factor specific for endoplasmic reticulum stress caused by misfolded proteins, was associated with bipolar disorders and schizophrenia in a Japanese population. Abuse of methamphetamine often produces affective disorders such as manic state, depressive state, and psychosis resembling paranoid-type schizophrenia. To clarify a possible involvement of XBP-1 in the etiology of methamphetamine dependence, we examined the genetic association of the -116C/G polymorphism of the XBP-1 gene by a case-control study. We found no significant association in allele and genotype frequencies of the polymorphism either with methamphetamine dependence or any clinical phenotype of dependence. Because the polymorphism is located in the promoter region of the XBP-1 gene and affects transcription activity of the gene, it is unlikely that dysfunction of XBP-1 may induces susceptibility to methamphetamine dependence.

Adult↗

PubMed2005

The GABA type A receptor alpha5 subunit gene is associated with bipolar I disorder.

Several genetic studies have revealed that bipolar disorders are linked with the chromosomal locus of 15q11-q13, where the gamma-aminobutyric acid (GABA) receptor alpha5 subunit gene (GABRA5) locates. GABA is one of the major neurotransmitters that may be involved in the pathogenesis of bipolar disorder. Five polymorphisms in the GABRA5 gene, -754C>T in the promoter region, IVS1-21G>A, IVS2-26T>A, (*)302C>T in 3'-UTR of exon 5, and a CA repeat polymorphism in the 3' flanking region were examined in a Japanese population. IVS1-21G>A exhibited significant differences in the distribution of the genotype and allele frequency in bipolar I disorder patients but not in bipolar II disorder patients, compared with control subjects. The haplotype analysis showed that IVS1-21G>A/IVS2-26A>T was associated with bipolar I disorder, and the IVS1-21A/IVS2-26T haplotype was a negative risk factor for susceptibility to the disorders (odds ratio: 0.57, 95% confidence interval: 0.44-0.73). These results suggest that the GABRA5 gene may confer susceptibility to bipolar I disorder.

Bipolar Disorder↗

PubMed2005

Parkin mediates nonclassical, proteasomal-independent ubiquitination of synphilin-1: implications for Lewy body formation.

It is widely accepted that the familial Parkinson's disease (PD)-linked gene product, parkin, functions as a ubiquitin ligase involved in protein turnover via the ubiquitin-proteasome system. Substrates ubiquitinated by parkin are hence thought to be destined for proteasomal degradation. Because we demonstrated previously that parkin interacts with and ubiquitinates synphilin-1, we initially expected synphilin-1 degradation to be enhanced in the presence of parkin. Contrary to our expectation, we found that synphilin-1 is normally ubiquitinated by parkin in a nonclassical, proteasomal-independent manner that involves lysine 63 (K63)-linked polyubiquitin chain formation. Parkin-mediated degradation of synphilin-1 occurs appreciably only at an unusually high parkin to synphilin-1 expression ratio or when primed for lysine 48 (K48)-linked ubiquitination. In addition we found that parkin-mediated ubiquitination of proteins within Lewy-body-like inclusions formed by the coexpression of synphilin-1, alpha-synuclein, and parkin occurs predominantly via K63 linkages and that the formation of these inclusions is enhanced by K63-linked ubiquitination. Our results suggest that parkin is a dual-function ubiquitin ligase and that K63-linked ubiquitination of synphilin-1 by parkin may be involved in the formation of Lewy body inclusions associated with PD.

Carrier Proteins↗

PubMed2005

Tissue distribution and hormonal regulation of the breast cancer resistance protein (Bcrp/Abcg2) in rats and mice.

Breast cancer resistance protein (Bcrp/Abcg2) is a member of the ABC transporter family. The purpose of this study was to quantify Bcrp mRNA in rat and mouse tissues, and to determine whether there are gender differences in Bcrp mRNA expression. Rat Bcrp mRNA levels were high in intestine and male kidney, and intermediate in testes. Mouse Bcrp expression was highest in kidney, followed by liver, ileum, and testes. Male-predominant expression of Bcrp was observed in rat kidney and mouse liver. Furthermore, gonadectomy and hypophysectomy experiments were conducted to determine whether sex steroids and/or growth hormone are responsible for Bcrp gender-divergent expression patterns. Male-predominant expression of Bcrp in rat kidney appears to be due to the suppressive effect of estradiol, and male-predominant expression of Bcrp in mouse liver appears to be due to the inductive effect of testosterone.

ATP Binding Cassette Transporter, Subfamily G, Mem↗

PubMed2005

Chest computed tomography of late invasive aspergillosis after allogeneic hematopoietic stem cell transplantation.

Computed tomography (CT) is a powerful diagnostic tool for invasive aspergillosis (IA) after allogeneic stem cell transplantation (allo-SCT); however, little information is available concerning CT findings of late IA after allo-SCT. To characterize CT findings of late IA, we retrospectively examined medical records and high-resolution CT findings of 27 allo-SCT recipients with late IA. Either acute or chronic GVHD was diagnosed in 24 patients. All 27 patients were given corticosteroids at IA diagnosis. High-resolution CT findings included halo (n=12), centrilobular nodules (n=12), ill-defined consolidation (n=13), ground-glass attenuation (n=8), pleural effusion (n=7), pleural-based consolidation (n=4), and cavitation (n=4). CT findings showing centrilobular nodules and either halo or cavitation were classified into bronchopneumonia type and angioinvasive type, respectively. Angioinvasive-type, bronchopneumonia-type, and combination-type IA were diagnosed in 11, 8, and 4 patients, respectively. CT findings were nonspecific in the other 4 patients. One bronchopneumonia-type case and 2 angioinvasive-type IA cases were subsequently diagnosed as combination type. Although there were no significant differences in patient characteristics between the 2 types of IA, bronchopneumonia-type IA had a poorer prognosis than angioinvasive IA ( P=.022). Halo is a useful diagnostic marker in late IA as well as early IA, and late IA frequently manifests as bronchopneumonia.

Adrenal Cortex Hormones↗

PubMed2005

Repetitive interactions observed in the crystal structure of a collagen-model peptide, [(Pro-Pro-Gly)9]3.

The crystal structure of a collagen-model peptide [(Pro-Pro-Gly)(9)](3) has been determined at 1.33 A resolution. Diffraction data were collected at 100 K using synchrotron radiation, which led to the first structural study of [(Pro-Pro-Gly)(n)](3) under cryogenic conditions. The crystals belong to the P2(1) space group with cell parameters of a = 25.95, b = 26.56, c = 80.14 Angstroms and beta = 90.0 degrees. The overall molecular conformation was consistent with the left-handed 7/2-helical model with an axial repeat of 20 A for native collagen. A total of 332 water molecules were found in an asymmetric unit. Proline residues in adjacent triple-helices exhibited three types of hydrophobic interactions. Furthermore, three types of hydrogen-bonding networks mediated by water molecules were observed between adjacent triple-helices. These hydrophobic interactions and hydrogen-bonding networks occurred at intervals of 20 Angstroms along the c-axis based on the previous sub-cell structures [(Pro-Pro-Gly)(n)](3) (n = 9, 10), which were also seen in the full-cell structure of [(Pro-Pro-Gly)(10)](3). Five proline residues at the Y position in the X-Y-Gly triplet were found in a down-puckering conformation, this being inconsistent with the recently proposed propensity-based hypothesis. These proline residues were forced to adopt opposing puckering because of the prevailing hydrophobic interaction between triple-helices compared with the Pro:Pro stacking interaction within a triple-helix.

Collagen↗

PubMed2005

A variant of the sigma receptor type-1 gene is a protective factor for Alzheimer disease.

OBJECTIVE: Some preclinical evidence suggests that the sigma receptor type 1, which plays several roles in learning and memory, may also be involved in the pathogenesis of Alzheimer disease (AD). The authors provide here genetic evidence that the sigma receptor type 1 (SIGMAR1) gene is involved in susceptibility to AD. METHODS: Two polymorphisms of the SIGMAR1 gene, G-241T/C-240T and Q2P, were analyzed in a Japanese sample of 239 patients with AD and 227 comparisons subjects. These two polymorphisms were in complete linkage disequilibrium with each other, resulting in only two haplotypes, GC-241-240Q2 and TT-241-240P2. RESULTS: There was a significant association between AD and the TT-241-240P2 haplotype of the SIGMAR1 gene and its homozygote, found with late-onset, but not early-onset AD. After stratification by epsilon4 allele status of the apolipoprotein E gene, TT-241-240P2 homozygosity of the SIGMAR1 gene reduced the risk of AD in epsilon4 allele carriers by three-fourths. CONCLUSION: The present study suggests that the TT-241-240P2 haplotype of the SIGMAR1 gene, which decreases expression of the gene, may have a protective role against susceptibility to AD.

Aged↗

PubMed2005

Delusion of theft and phantom intruder delusion in demented elderly patients in Japan.

Delusion of theft and phantom intruder delusion are among the most frequent delusions in dementia. The purpose of this study was to clarify the clinical characteristics of patients with these symptoms. The authors conducted a questionnaire survey; items included age, gender, dementia diagnosis, cognitive function, and activities of daily living. Other clinical characteristics were evaluated using the quality of life questionnaire for dementia. A total of 217 patients with dementia were rated. Frequencies of delusion of theft were as follows: frequent, 7%; sometimes, 11%; rare, 16%; and none, 66%. Frequencies of phantom intruder delusion were as follows: frequent, 4%; sometimes, 10%; rare, 9%; and none, 77%. Comparison between positive and negative groups with these symptoms revealed that positive groups had higher scores in 2 of 6 domains of the quality of life questionnaire for dementia, namely, negative affect and actions, and restlessness. The positive group with delusion of theft had higher scores in cognitive function and activities of daily living than did the negative group. These results suggest that negative affect and action and restlessness might be related to delusion of theft or phantom intruder delusion and that delusion of theft frequently occurs in the early stage of dementia.

Activities of Daily Living↗

PubMed2005

Transfecting the multidrug resistance protein 2 gene improves transcellular organic anion transport.

Eisai hyperbilirubinuria rats (EHBRs) lack functionally active multidrug resistance protein 2 (Mrp2), which causes impaired biliary excretion of numerous organic anions. We previously reported that Mrp3 expression is enhanced while organic anion transporting polypeptide 1 (Oatp1) or Oatp2 expression is reduced in the liver of EHBRs. Mrp3 mediates basolateral efflux of organic anions but not canalicular export. In this study, we transfected the human MRP2 gene into the liver of EHBRs and evaluated whether its transfection improves transcellular transport of organic anions in hepatocytes of EHBRs. The protein expression vector (pDEST26) including the full-length human MRP2 cDNA was developed. This vector was mixed with the hemagglutinating virus of Japan (HJV) envelope protein and transfected into the liver of EHBRs via the portal vein. Expression of Mrp3, Oatp1 and Oatp2 was evaluated by reverse transcription-polymerase chain reaction and Western blot analysis. mRNA and protein expression of MRP2 were detected in hepatocytes from transfected EHBRs. The serum-conjugated bilirubin level in EHBRs decreased to a normal level (35.7 to 6.4 micromol/l) with the expression of human MRP2. The change in expression of Mrp3, Oatp1 and Oatp2 in the liver of EHBRs was normalized by transfecting MRP2. Transfection of human MRP2 was performed using the HJV envelope protein. Transfection of MRP2 is useful for improving the transcellular transport of organic anions in the livers of EHBRs.

ATP Binding Cassette Transporter, Subfamily B↗

PubMed2004

RERJ1, a jasmonic acid-responsive gene from rice, encodes a basic helix-loop-helix protein.

Differential screening of a cDNA library constructed using poly(A)(+) RNA from suspension-cultured rice cells treated with jasmonic acid (JA) for 1/2h yielded a cDNA of a gene tentatively named RERJ1 that is upregulated in response to exogenous JA. Northern blot analysis indicated that the RERJ1 mRNA levels peaked at 1/2-1h after the addition of jasmonic acid and then decreased gradually. RERJ1 encodes a transcriptional regulator with a basic helix-loop-helix motif. The phenotypes of transgenic rice plants overexpressing sense or antisense RERJ1 mRNA demonstrated that RERJ1 is involved in the growth inhibition of rice shoots caused by JA. Other biological functions of RERJ1 are discussed from an evolutionary standpoint.

Amino Acid Sequence↗

PubMed2004

A nonsynonymous polymorphism in the human fatty acid amide hydrolase gene did not associate with either methamphetamine dependence or schizophrenia.

Genetic contributions to the etiology of substance abuse and dependence are topics of major interest. Acute and chronic cannabis use can produce drug-induced psychosis resembling schizophrenia and worsen positive symptoms of schizophrenia. The endocannabinoid system is one of the most important neural signaling pathways implicated in substance abuse and dependence. The fatty acid amide hydrolase (FAAH) is a primary catabolic enzyme of endocannabinoids. To clarify a possible involvement of FAAH in the etiology of methamphetamine dependence/psychosis or schizophrenia, we examined the genetic association of a nonsynonymous polymorphism of the FAAH gene (Pro129Thr) by a case-control study. We found no significant association in allele and genotype frequencies of the polymorphism with either disorder. Because the Pro129Thr polymorphism reduces enzyme instability, it is unlikely that dysfunction of FAAH and enhanced endocannabinoid system induce susceptibility to either methamphetamine dependence/psychosis or schizophrenia.

Adult↗

PubMed2004

Prevalence and time of appearance of Brugada electrocardiographic pattern in young male adolescents from a three-year follow-up study.

The prevalence of Brugada's electrocardiographic (ECG) pattern in 7,022 male adolescents in the seventh grade was determined, and the same subjects were reexamined 3 years later, while in tenth grade. Two subjects (0.03%) and 7 subjects (0.10%) showed Brugada's ECG pattern by the conventional criterion (J point or ST-segment >/=0.1 mV in leads V(1) to V(3)), and no subjects (0%) and 2 subjects (0.03%) fulfilled the recent criterion (J point or ST-segment >/=0.2 mV) in the seventh and tenth grades, respectively, indicating that Brugada's ECG pattern begins to appear during junior high school and increases until late adulthood.

Adolescent↗