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C Uchida

Publications and source records attributed to C Uchida.

At least 19 recordsLinked to original sources
PubMed2006

Ablation of a peptidyl prolyl isomerase Pin1 from p53-null mice accelerated thymic hyperplasia by increasing the level of the intracellular form of Notch1.

Tumor suppressor p53 is essential for checkpoint control in response to a variety of genotoxic stresses. DNA damage leads to phosphorylation on the Ser/Thr-Pro motifs of p53, which facilitates interaction with Pin1, a pSer/pThr-Pro-specific peptidyl prolyl isomerase. Pin1 is required for the timely activation of p53, resulting in apoptosis or cell cycle arrest. To investigate the physiological relationship between Pin1 and p53, we created Pin1-/-p53-/- mice. These p53-deficient mice spontaneously developed lymphomas, mainly of thymic origin, as well as generalized lymphoma infiltration into other organs, including the liver, kidneys and lungs. Ablation of Pin1, in addition to p53, accelerated the thymic hyperplasia, but the thymocytes in these Pin1-/-p53-/- mice did not infiltrate other organs. The thymocytes in 12-week-old Pin1-/-p53-/- mice were CD4(-)CD8(-) (double negative) and had significantly higher levels of the intracellular form of Notch1 (NIC) than the thymocytes of p53-/- or wild-type mice. Presenilin-1, a cleavage enzyme for NIC generation from full-length Notch1 was increased in the thymocytes of Pin1-/-p53-/- mice. Pin1 depletion also inhibited the degradation of NIC by proteasomes. These results suggest that both Pin1 and p53 control the normal proliferation and differentiation of thymocytes by regulating the NIC level.

Animals↗
PubMed2006

Ubiquitin-dependent degradation of SnoN and Ski is increased in renal fibrosis induced by obstructive injury.

Transforming growth factor-beta (TGF-beta) plays a critical role in the progression of renal fibrosis. The activity of TGF-beta is tightly controlled by various mechanisms, among which antagonizing Smad-mediated gene transcription by co-repressors represents one of the important components. We investigated the expression, degradation, and ubiquitination of Smad transcriptional co-repressors SnoN (ski-related novel gene N) and Ski (Sloan-Kettering Institute proto-oncogene) in renal fibrogenesis. We also studied the involvement of Smad-ubiquitination regulatory factor 2 (Smurf2) in ubiquitination of SnoN protein. The kidneys of mice with unilateral ureteral obstruction (UUO) and those of sham-operated mice were used. Renal lesions and the expression of TGF-beta1, type I collagen, SnoN, Ski, and Smurf2 were examined by immunohistochemistry, Western blot, and/or real-time reverse transcriptase-polymerase chain reaction. Degradation and ubiquitination of SnoN/Ski proteins were also investigated. The obstructed kidneys of UUO mice showed progressive tubulointerstitial fibrosis, high expression levels of TGF-beta1, type I collagen, SnoN and Ski mRNAs, and low levels of SnoN and Ski proteins. Both degradation and ubiquitination of SnoN/Ski proteins were markedly increased in the obstructed kidneys, in which Smurf2 expression was increased. Smurf2 immunodepletion in extracts of obstructed kidneys resulted in reduced ubiquitination of SnoN. Our results suggest that the reduction of SnoN/Ski proteins resulting from increased ubiquitin-dependent degradation is involved in the progression of tubulointerstitial fibrosis.

Animals↗
PubMed2001

Involvement of CCAAT/enhancer-binding protein in regulation of the rat serine:pyruvate/alanine:glyoxylate aminotransferase gene expression.

In the rat liver, transcription of the serine:pyruvate/alanine:glyoxylate aminotransferase (SPT/AGT) gene occurs from two sites, +1 and +66, in exon 1, resulting in the formation of two mRNAs, one for a precursor of mitochondrial SPT/AGT and the other for peroxisomal SPT/AGT, respectively. In this study, we attempted to characterize the downstream promoter responsible for generation of peroxisomal SPT/AGT. The minimal downstream promoter was confined to the +21-+90 region. We demonstrated that C/EBPalpha and C/EBPbeta bound around the downstream start site (+66) contribute to the promoter activity. The downstream promoter activity is also regulated positively by a short inverted repeat, located 20-30 bp upstream of the downstream start site, through a protein factor(s) bound to this region. On the other hand, the sequence just downstream of the start site may negatively regulate the promoter activity.

Animals↗
PubMed2000

Localization of initial lymph node metastasis from carcinoma of the thoracic esophagus.

BACKGROUND: Most surgeons consider esophageal carcinoma with lymph node involvement a systemic disease. However, it is possible that the disease may be localized in the earlier phases of lymphatic metastasis. The distribution of involved lesions in the initial phase of lymph node metastasis has not been thoroughly investigated yet. METHODS: Among 329 patients that underwent curative (R0 International Union Against Cancer [UICC]) esophagectomy with systematic mesoesophageal dissection, 51 cases of patients with only 1 involved lymph node (solitary involvement) were retrospectively investigated and compared with patients with multiple involved lymph nodes. The regional lymph nodes were divided into the thoracocervical junction group (lower deep cervical and recurrent nerve lymph nodes), perigastric group, and intrathoracic group. RESULTS: Lymph node involvement was limited to a solitary lymph node in 46% of lymph node positive patients with esophageal carcinoma confined to the wall (T1 and T2, UICC) and in 17% of lymph node positive patients with cancer that invaded the extramural layer (T3 and T4, UICC). Of patients with solitary involvement, 82% had a positive thoracocervical junction or perigastric lymph node. The 5-year survival rate in solitary involvement cases was 61%, and 65% when solitary involvement was not intrathoracic. Most of the 5-year survivors had involvement of a thoracocervical junction or perigastric lymph node and had not received systemic chemotherapy. CONCLUSIONS: Solitary involvement was not rare and not directly associated with a disseminated disease. Solitary involvement was commonly located in the thoracocervical junction or abdomen that are accessible without thoracotomy. Systematic dissection of the regional lymph nodes including thoracocervical junction and perigastric groups is recommended for resectable esophageal carcinoma at this time. However, less extensive dissection may be performed in selected cases if the sentinel lymph node concept proves valid.

Esophageal Neoplasms↗
PubMed2000

Expanded polyglutamine stretches interact with TAFII130, interfering with CREB-dependent transcription.

At least eight inherited neurodegenerative diseases are caused by expanded CAG repeats encoding polyglutamine (polyQ) stretches. Although cytotoxicities of expanded polyQ stretches are implicated, the molecular mechanisms of neurodegeneration remain unclear. We found that expanded polyQ stretches preferentially bind to TAFII130, a coactivator involved in cAMP-responsive element binding protein (CREB)-dependent transcriptional activation, and strongly suppress CREB-dependent transcriptional activation. The suppression of CREB-dependent transcription and the cell death induced by polyQ stretches were restored by the co-expression of TAFII130. Our results indicate that interference of transcription by the binding of TAFII130 with expanded polyQ stretches is involved in the pathogenetic mechanisms underlying neurodegeneration.

Aged↗
PubMed2000

Mitochondrial targeting signal-induced conformational change and repression of the peroxisomal targeting signal of the precursor for rat liver serine:pyruvate/alanine:glyoxylate aminotransferase.

In the rat liver, two mRNAs for serine:pyruvate (or alanine:glyoxylate) aminotransferase are generated from a single gene by alternative transcription initiation. The longer mRNA encodes a precursor of a mitochondrial enzyme that has a mitochondrial targeting signal at the N-terminus and is translocated into mitochondria. The shorter mRNA encodes a peroxisomal enzyme of mature size that is imported into peroxisomes. We have been interested in the mechanism of selective targeting to mitochondria of the precursor protein that also contains a peroxisomal targeting signal in the molecule. In this study, we examined the effect of the mitochondrial targeting signal on the conformation of the protein and on the function of the peroxisomal targeting signal in the precursor molecule. The results suggest that the mitochondrial targeting signal causes the conformation of the protein to become unfolded and that this conformational change in turn causes repression of the putative peroxisomal targeting signal contained in the precursor protein.

Alternative Splicing↗
PubMed2000

Store depletion by caffeine/ryanodine activates capacitative Ca(2+) entry in nonexcitable A549 cells.

Capacitative Ca(2+) entry is essential for refilling intracellular Ca(2+) stores and is thought to be regulated primarily by inositol 1, 4,5-trisphosphate (IP(3))-sensitive stores in nonexcitable cells. In nonexcitable A549 cells, the application of caffeine or ryanodine induces Ca(2+) release in the absence of extracellular Ca(2+) similar to that induced by thapsigargin (Tg), and Ca(2+) entry occurs upon the readdition of extracellular Ca(2+). The channels thus activated are also permeable to Mn(2+). The channels responsible for this effect appear to be activated by the depletion of caffeine/ryanodine-sensitive stores per se, as evidenced by the activation even in the absence of increased intracellular Ca(2+) concentration. Tg pretreatment abrogates the response to caffeine/ryanodine, whereas Tg application subsequent to caffeine/ryanodine treatment induces further Ca(2+) release. The response to caffeine/ryanodine is also abolished by initial ATP application, whereas ATP added subsequent to caffeine/ryanodine induces additional Ca(2+) release. RT-PCR analyses showed the expression of a type 1 ryanodine receptor, two human homologues of transient receptor potential protein (hTrp1 and hTrp6), as well as all three types of the IP(3) receptor. These results suggest that in A549 cells, (i) capacitative Ca(2+) entry can also be regulated by caffeine/ryanodine-sensitive stores, and (ii) the RyR-gated stores interact functionally with those sensitive to IP(3), probably via Ca(2+)-induced Ca(2+) release.

Caffeine↗
PubMed2000

Effect of erythromycin on ATP-induced intracellular calcium response in A549 cells.

ATP induced a biphasic increase in the intracellular Ca(2+)concentration ([Ca(2+)](i)), an initial spike, and a subsequent plateau in A549 cells. Erythromycin (EM) suppressed the ATP-induced [Ca(2+)](i) spike but only in the presence of extracellular calcium (Ca(2+)(o)). It was ineffective against ATP- and UTP-induced inositol 1,4,5-trisphosphate [Ins(1,4,5)P(3)] formation and UTP-induced [Ca(2+)](i) spike, implying that EM perturbs Ca(2+) influx from the extracellular space rather than Ca(2+)release from intracellular Ca(2+) stores via the G protein-phospholipase C-Ins(1,4,5)P(3) pathway. A verapamil-sensitive, KCl-induced increase in [Ca(2+)](i) and the Ca(2+) influx activated by Ca(2+) store depletion were insensitive to EM. 3'-O-(4-benzoylbenzoyl)-ATP evoked an Ca(2+)(o)-dependent [Ca(2+)](i) response even in the presence of verapamil or the absence of extracellular Na(+), and this response was almost completely abolished by EM pretreatment. RT-PCR analyses revealed that P2X(4) as well as P2Y(2), P2Y(4), and P2Y(6) are coexpressed in this cell line. These results suggest that in A549 cells 1) the coexpressed P2X(4) and P2Y(2)/P2Y(4) subtypes contribute to the ATP-induced [Ca(2+)](i) spike and 2) EM selectively inhibits Ca(2+) influx through the P2X channel. This action of EM may underlie its clinical efficacy in the treatment of airway inflammation.

3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethy↗
PubMed2000

Oxalate synthesis in mammals: properties and subcellular distribution of serine:pyruvate/alanine:glyoxylate aminotransferase in the liver.

Primary hyperoxaluria Type 1 (PH1) is caused by a functional deficiency of a liver enzyme, serine:pyruvate/alanine:glyoxylate aminotransferase (SPT/AGT), which catalyzes transamination between L-serine or l-alanine as an amino acid substrate and glyoxylate or pyruvate as an alpha-keto acid substrate. A high affinity for glyoxylate is a notable feature of this enzyme, suggesting a role in glyoxylate metabolism in vivo. Another conspicuous feature of SPT/AGT is its species-specific and food habit-dependent subcellular distribution. Thus, the enzyme is located in peroxisomes in herbivores and man, largely in mitochondria in carnivores, and in both the organelles in rodents. The mechanism of the species-specific dual organelle localization of SPT/AGT is either transcription of the gene from two different start sites or loss of the upstream translation initiation ATG codon by mutations. It appears that the mitochondrial versus peroxisomal distribution of SPT/AGT in different animal species is indispensable in meeting the metabolic needs caused by their respective food habits. As for the peroxisomal localization, glycolate is contained in plants much more than in animal tissues, and when ingested, it is converted to glyoxylate, an immediate precursor of oxalate, in liver peroxisomes. Therefore, peroxisomal localization of SPT/AGT may be indispensable for herbivores to convert the glyoxylate formed in peroxisomes into glycine in situ rather than forming oxalate. On the other hand, our recent studies showed that SPT/AGT contributed substantially to serine metabolism in rabbit, human, and dog livers; i.e., irrespective of its mitochondrial or peroxisomal localization. Thus, the mitochondrial localization of SPT/AGT was not a prerequisite for the metabolism of L-serine. Another source of glyoxylate is the metabolism of L-hydroxyproline, and in this case, the enzyme responsible for the glyoxylate formation has been reported to be a mitochondrial matrix enzyme. Collagen accounts for about 30% of total animal proteins and contains about 13% (w/w) hydroxyproline. It is therefore possible that both mitochondrial and peroxisomal SPT/AGT contribute to the metabolism of glyoxylate and serine, but the subcellular site for glyoxylate metabolism is different in herbivores and carnivores.

Animals↗
PubMed1999

Mice lacking Pin1 develop normally, but are defective in entering cell cycle from G(0) arrest.

The peptidyl prolil cis/trans isomerase Ess1/Pin1 is essential for mitosis progression in yeast cells and is hypothesized to perform the same role in mammalian cells. To investigate the function of Pin1 in mammalian cells, we created mice lacking Pin1. These mice underwent normal development. Although the embryonic Pin1-/- fibroblasts grew normally, they proved significantly deficient in their ability to restart proliferation in response to serum stimulation after G(0) arrest. These results suggest that Pin1 is required for cell cycle progression from G(0) arrest as well as mitosis progression in normal mammalian cells.

Amino Acid Sequence↗
PubMed1998

Synthesis of alpha-glucosidase inhibitors: kojibiose-type pseudo-disaccharides and a related pseudotrisaccharide.

Two kojibiose-type pseudo-disaccharides and a trisaccharide, containing a 5-amino-1,2,3,4-cyclopentanetetrol derivative or valienamine, linked by way of nitrogen bridges to the sugar residues, have been designed and synthesized as processing alpha-glucosidase I inhibitors. Synthesis of the pseudo-disaccharides was carried out starting from the coupling products of the sugar isothiocyanates and an aminocyclitol, respectively, by cyclization with mercury(II) oxide to the cyclic isoureas and subsequent deprotection. Pseudokojibiose was prepared in a poor yield by reaction of a protected valienamine and a sugar epoxide, followed by deprotection. Although the pseudooligosaccharides are all strong inhibitors of alpha-glucosidase (baker's yeast), they did not have any inhibitory potency against either sucrase isomaltase (rat intestine) or processing alpha-glucosidase (rat liver microsomes).

Animals↗
PubMed1997

RNA helicase A mediates association of CBP with RNA polymerase II.

The coactivator CBP has been proposed to stimulate the expression of certain signal-dependent genes via its association with RNA polymerase II complexes. Here we show that complex formation between CBP and RNA polymerase II requires RNA helicase A (RHA), a nuclear DNA/RNA helicase that is related to the Drosophila male dosage compensation factor mle. In transient transfection assays, RHA was found to cooperate with CBP in mediating target gene activation via the CAMP responsive factor CREB. As a mutation in RHA that compromised its helicase activity correspondingly reduced CREB-dependent transcription, we propose that RHA may induce local changes in chromatin structure that promote engagement of the transcriptional apparatus on signal responsive promoters.

Animals↗
PubMed1997

Analysis of a cAMP-responsive activator reveals a two-component mechanism for transcriptional induction via signal-dependent factors.

We have examined the mechanism by which the cAMP-responsive factor CREB stimulates target gene expression following its phosphorylation at Ser-133. Using an in vitro transcription assay, we found that two signals were required for target gene activation: a phospho(Ser-133)-dependent interaction of CREB with RNA polymerase II via the coactivator CBP and a glutamine-rich domain interaction with TFIID via hTAF(II)130. The adenovirus E1A oncoprotein was found to inhibit phospho(Ser-133) CREB activity by binding to CBP and specifically blocking recruitment of RNA Pol II to the promoter. Our results suggest that the recruitment of CBP-RNA Pol II complexes per se is not sufficient for transcriptional activation and that activator-mediated recruitment of TFIID is additionally required for induction of signal-dependent genes.

Adenovirus E1A Proteins↗
PubMed1997

Synthesis and biological evaluation of potent glycosidase inhibitors: N-phenyl cyclic isourea derivatives of 5-amino- and 5-amino-C-(hydroxymethyl)-1,2,3,4-cyclopentanetetraols.

Twenty-four stereoisomers of 5-amino- and 5-amino-C-(hydroxymethyl)-1,2,3,4-cyclopentanetetraols and twenty-six of the corresponding N-phenyl cyclic isourea derivatives were assayed for inhibitory activity against six glycosidases. Among them, as has been expected for structure mimics of putative transition state glucopyranosyl cation for glycoside hydrolysis, 1L-(1,2,4,5/3)-5-amino-1-C-(hydroxymethyl)-1,2,3,4-cyclopentanetetrao l L-4 and its N-phenyl cyclic isourea derivative S-19 were shown to have strong inhibitory activity, IC50 4 x 10(-7) and 7.6 x 10(-9) M, respectively, against baker's yeast alpha-glucosidase. It has been analogously explained that compounds R,S-22 and R,S-26 possessed high inhibitory potency against Escherichia coli and bovine liver beta-galactosidases, respectively.

Animals↗
PubMed1996

Synthesis and inhibitory activity of glycosidase inhibitors, glycosylamino-oxazolines.

In connection with structural modification of the trehalase inhibitor trehazolin (1), as a new-type of glycohydrolase inhibitor, some glycosylamino-oxazolines were designed and synthesized. Among three oxazolines beta-galacto (3), beta-gluco (5) and alpha-manno-types (6) obtained in stable form, the latter 6 has been shown to possess a moderate inhibitory activity against alpha-mannosidase.

Animals↗
PubMed1995

Further chemical modification of trehalase inhibitor trehazolin: structure and inhibitory-activity relationship of the inhibitor.

Eight analogues of trehazolin were synthesized and tested for trehalase inhibitors. Deoxygenation of the cyclopentanepolyol moiety all decreased the inhibitory activity. Epimerization at the branching point of the cyclopentane ring did not so affect the potency. The cyclic isourea part was shown to be replaced with guanidine structure with a considerable decrease of activity. The 6'-fluoro-6'-deoxy derivative was still a strong inhibitor. It seems that trehazolin strictly mimies the substrate alpha, alpha-trehalose and any structural change and/or removal of the hydroxyl functions appreciably influence its potency. The present results led to finding 5-aminocyclopentane-1,2,3,4-tetraols to be new lead compounds for glycohydrolase inhibitors.

Animals↗
PubMed1994

Regulation by glucagon of serine: pyruvate/alanine: glyoxylate aminotransferase gene expression in cultured rat hepatocytes.

The effects of glucagon on serine: pyruvate/alanine: glyoxylate aminotransferase (SPT/AGT) gene expression were studied in primary cultured rat hepatocytes. When hepatocytes had been precultured for 16-18 h under serum- and hormone-free conditions, the addition of glucagon caused (after a lag period of about 2 h) a remarkable increase in the cellular level of SPT/AGT mRNA by 4 h in a time- and dose-dependent manner. The induced mRNA was that for mitochondrial SPT/AGT, as judged by ribonuclease protection analysis. A nuclear run-on assay revealed that activation of transcription is responsible for the increase in mitochondrial SPT/AGT mRNA and that the maximal rate of transcription occurs 1.5 h after glucagon addition. The effect of glucagon was mimicked by 8-bromo-cAMP and suppressed by N-[2-(p-bromocinnamylamino)ethyl]-5-isoquinolinesulfonamide, an inhibitor of cAMP-dependent protein kinase (protein kinase A), while both 12-O-tetradecanoylphorbol-13-acetate and A23187 were without effect in elevating the SPT/AGT mRNA level, suggesting that the cAMP/protein kinase A system is involved in the regulation of SPT/AGT gene expression. In hepatocytes precultured for 16-18 h under serum- and hormone-free conditions, the glucagon-induced transcription was severely inhibited by cycloheximide. When the preculture was for 2 h, on the other hand, the activation of transcription by glucagon was more rapid, and the inhibition by cycloheximide was less than that observed with cells precultured for 16-18 h, suggesting that a short-lived protein factor is involved in the hormonal regulation. The glucagon-induced expression of the SPT/AGT gene was also turned off by dexamethasone.

8-Bromo Cyclic Adenosine Monophosphate↗