Biomedical subjects

M Katoh

Publications and source records attributed to M Katoh.

At least 91 records · Page 5Linked to original sources

PubMed2001

Molecular cloning, gene structure, and expression analyses of NKD1 and NKD2.

Mouse Nkd is a Dishevelled-binding protein, functioning as a negative regulator of WNT - beta-catenin - TCF signaling pathway. Here, human NKD1 and NKD2 were cloned and characterized. NKD1 and NKD2 were predicted to encode 470- and 451-amino-acid polypeptide, respectively. NKD1 and NKD2, showing 43.8% total amino-acid identity, were more homologous in the NH1, NH2, NH3, and NH4 domains. The NH2 domain of NKD1 and NKD2 contained the EF-hand motif. Exon-intron structures of NKD1 and NKD2 genes, consisting of 10 exons, were well conserved. NKD1 was highly expressed in fetal kidney, while NKD2 was moderately expressed in fetal kidney, lung, and adult lung. NKD1 was up-regulated in colorectal cancer cell line SW480, gastric cancer cell line TMK1, and pancreatic cancer cell line Hs700T. NKD2 was up-regulated in gastric cancer cell line MKN45, pancreatic cancer cell line BxPC-3, and esophageal cancer cell lines TE6, and TE13. NKD1 and NKD2 were up-regulated together in 1 case of primary gastric cancer out of 10 cases, and were down-regulated together in 2 cases. Up-regulation of NKD1 or NKD2 might be due to a negative feed-back mechanism. Alternatively, genetic alteration of NKD1 or NKD2 might lead to activation of the WNT - beta-catenin - TCF signaling pathway.

Adaptor Proteins, Signal Transducing↗

PubMed2000

Effect of YM-126414 on glucose uptake and redistribution of glucose transporter isotype 4 in muscle cells.

We discovered a novel compound, YM-126414 [1,3, 3-trimethyl-2-(2-phenylaminovinyl)-3H-indolium perchlorate], which stimulates glucose uptake in skeletal muscle cells in vitro. This compound increased the rate of consumption of glucose by C2C12 mouse myoblast cells in a dose-dependent manner (EC(50)=10 nM). To investigate the mechanism of this stimulation, we determined the redistribution of insulin-regulatable glucose transporter isotype 4 (Glut4). When fully differentiated C2C12 cells stably expressing myc-tagged Glut4 protein were treated with YM-126414, redistribution was dramatically increased in a dose-dependent manner (EC(50)=21 nM). These results indicate that YM-126414 is a novel glucose uptake stimulator for muscle cells by causing up-regulation of Glut4 redistribution in differentiated muscle cells. Our findings for the in vitro effects of YM-126414 suggest a direction for the development of new drugs for the treatment of type 2 diabetes.

Animals↗

PubMed2000

Heat shock protein expression in human tumours grown in severe combined immunodeficient mice.

The constitutional expression of heat shock proteins (HSP) 27, 70 and 90 in human breast, colon and ovarian cancer cells transplanted into severe combined immunodeficient (SCID) mice was evaluated. In addition their induced expression under chemotherapeutic stress was analyzed. The oestrogen receptor positive breast cancer cell lines (MCF-7, T47D) demonstrated an increased level of HSP 27 and 70 expression compared with oestrogen receptor negative cell lines (BT20, HBL100). After 5-fluorouracil application for 4 days, HSP 27 and 70 expression was increased in HT29 colon tumours. Hence, the human/SCID mouse model is well suited to evaluate the constitutional and induced expression of human HSPs under various experimental conditions.

Adenocarcinoma↗

PubMed2000

Isolation of Xenopus frizzled-10A and frizzled-10B genomic clones and their expression in adult tissues and embryos.

Frizzled genes, encoding WNT receptors, play key roles in cell fate determination. Here, we isolated two Xenopus frizzled genes (Xfz10A and Xfz10B), probably reflecting pseudotetraploidy in Xenopus. Xfz10A (586 amino acids) and Xfz10B (580 amino acids) both encoded by a single exon, consisted of the N-terminal cysteine-rich domain, seven transmembrane domains, and the C-terminal Ser/Thr-X-Val motif. Xfz10A and Xfz10B were 97.0% identical at the amino acid level, and Xfz10B was 100% identical to previously reported Xfz9, yet Xfz10A was 85.3% and 62.4% identical to FZD10 and FZD9, respectively. Xfz10 mRNA appeared as 3.4 kb in adult tissues and embryos. RT-PCR analyses revealed the expression of more Xfz10A mRNA in stomach, kidney, eye, skeletal muscle, and skin, and more Xfz10B mRNA in heart and ovary, but in embryos, two mRNAs were equally expressed from the blastula stage with their peak expression at the late gastrula stage. The main site of Xfz10 mRNA expression was neural fold at the neurula stage and the dorsal region of midbrain, hindbrain, and spinal cord at the tadpole stage. These results suggest that Xfz10 has important roles in neural tissue formation.

Amino Acid Sequence↗

PubMed2000

Mitomycin C resistance induced by TCF-3 overexpression in gastric cancer cell line MKN28 is associated with DT-diaphorase down-regulation.

TCF transcription factors are mediators of the WNT signaling pathway and are antagonized by the transforming growth factor beta signaling pathway. Here human TCF-3 has been cloned and characterized. Differential expression analyses of TCF genes in gastric cancer revealed that TCF-1 was expressed in most cases of primary gastric cancer at almost the same level as in normal gastric mucosa and that TCF-3 was occasionally up-regulated in primary gastric cancer. The TCF-3 expression vector was transfected to gastric cancer cell line MKN28 to establish stable transformants. Three independent MKN28 transformants overexpressing TCF-3 showed about 8-fold resistance to mitomycin C (MMC; IC50, 2.4 microg/ml) compared with MKN28 vector transfectants (IC50 = 0.3 microg/ml). Among the 10 drug resistance-associated genes examined in this study, the DT-diaphorase (DTD) gene was down-regulated in three MKN28 transformants overexpressing TCF-3. DTD mRNA was also down-regulated in primary gastric cancer with TCF-3 up-regulation. In addition, DTD protein was down-regulated in three MKN28 transformants overexpressing TCF-3 compared with MKN28 vector transfectants. DTD is implicated in the activation of MMC in target cells, and DTD down-regulation explains MMC resistance. MMC resistance induced by TCF-3 overexpression is probably due to DTD down-regulation, which might provide a possible target for new therapy of drug-resistant gastric cancer.

Amino Acid Sequence↗

PubMed2000

Alternative splicing of the WNT-2B/WNT-13 gene.

Secreted glycoprotein WNTs play important roles in carcinogenesis and development. We have previously reported molecular cloning of WNT-2B/WNT-13. Here, we have isolated a novel WNT-2B isoform (WNT-2B2), in addition to the original WNT-2B isoform (WNT-2B1). WNT-2B1 and WNT-2B2 are completely different in the 5'-UTR and in the N-terminal part of the coding region. The N-terminal hydrophobic domain is contained in WNT-2B1, but not in WNT-2B2. WNT-2B1 and WNT-2B2 share the WNT-core domain, and show 87.0% amino-acid identity. We have determined the structure of the WNT-2B gene. The WNT-2B1 mRNA consists of exons 1, 2, and 4-7, while the WNT-2B2 mRNA consists of exons 3-7. WNT-2B2 was expressed in fetal brain, fetal lung, fetal kidney, caudate nucleus, testis, glioblastoma cell lines A172, SW1783, gastric cancer cell lines MKN28, MKN74, and cervical cancer cell line HeLa S3. WNT-2B1 expression level was relatively higher in fetal brain and fetal lung than in other tissues or cell lines expressing WNT-2B2. These results indicate that the WNT-2B1 and WNT-2B2 mRNAs are transcribed due to alternative splicing with distinct expression profile. This is the first report on the WNT isoforms derived from the same gene due to alternative splicing.

5' Untranslated Regions↗

PubMed2000

Increased activity of nuclear factor-kappaB participates in cardiovascular remodeling induced by chronic inhibition of nitric oxide synthesis in rats.

BACKGROUND: Chronic inhibition of endothelial nitric oxide (NO) synthesis by the administration of N(omega)-nitro-L-arginine methyl ester (L-NAME) to rats induces early vascular inflammatory changes [monocyte infiltration into coronary vessels, nuclear factor-kappaB (NF-kappaB) activation, and monocyte chemoattractant protein-1 expression] as well as subsequent arteriosclerosis (medial thickening and perivascular fibrosis) and cardiac fibrosis. However, no direct evidence for the importance of NF-kappaB in this process is known. METHODS AND RESULTS: We examined the effect of a cis element decoy strategy to address the functional importance of NF-kappaB in the pathogenesis of cardiovascular remodeling. We found here that in vivo transfection of cis element decoy oligodeoxynucleotides against NF-kappaB to hearts prevented the L-NAME-induced early inflammation and subsequent coronary vascular medial thickening. In contrast, NF-kappaB decoy oligodeoxynucleotide transfection did not decrease the development of fibrosis, the expression of transforming growth factor-beta(1) mRNA, or systolic pressure overload induced by L-NAME administration. CONCLUSIONS: The NF-kappaB system participates importantly in the development of early vascular inflammation and subsequent medial thickening but not in fibrogenesis in this model. The present study may provide a new aspect of how endothelium-derived NO contributes to anti-inflammatory and/or antiarteriosclerotic properties of the vascular endothelium in vivo.

Animals↗

PubMed2000

cDNA Cloning and mRNA analysis of PGC-1 in epitrochlearis muscle in swimming-exercised rats.

Peroxisome proliferator-activated receptor gamma coactivator-1 (PGC-1), a cold-inducible coactivator of nuclear receptors, stimulates mitochondrial biogenesis and respiration in muscle cells. In the present study, we first cloned a rat PGC-1 gene from a brown adipose tissue cDNA library which encodes a predicted 796-amino-acid protein and exhibits respectively 98% and 95% identity with the mouse and human homologues. Next, we examined the effect of swimming exercise training on the level of expression of the PGC-1 gene in rat epitrochlearis (Epi) muscle. PGC-1 mRNA level in Epi muscle in rats that swam 2 h a day for 3 and 7 days increased dramatically by 154% and 163%, respectively, compared to the non-exercised control group. PGC-1 mRNA up-regulation was not observed in an immersion group treated at 35 degrees C during the training program but without swimming exercise. These results demonstrate that expression of the PGC-1 gene in Epi muscle is induced not only by cold exposure but also by prolonged low-intensity physical exercise.

Animals↗

PubMed2000

Molecular cloning and characterization of human FGF-20 on chromosome 8p21.3-p22.

The fibroblast growth factors (FGFs) play important roles in morphogenesis, angiogenesis, tissue remodeling, and carcinogenesis. Human FGF-20 has been cloned and characterized in this study. FGF-20 encodes a 211-amino-acid polypeptide with the FGF-core domain. A strong hydrophobic region was found in the FGF-core domain of FGF-20; however, no typical N-terminal signal sequence was found in FGF-20, just as in FGF-9 and FGF-16. Total amino acid identities are as follows: FGF-20 vs FGF-9, 71.6%; FGF-20 vs FGF-16, 66.2%; FGF-9 vs FGF-16, 72.4%. Phylogenic analysis indicated that FGF-20, FGF-9, and FGF-16 constitute a subfamily among the FGF family. FGF-20 mRNA of 2.4 kb in size was detected in colon cancer cell line SW480 by Northern blot analysis. Lower levels of FGF-20 mRNA were detected in human fetal tissues and primary cancers by cDNA-PCR. The nucleotide sequence of FGF-20 cDNA is split into three parts in the human genome sequence of the chromosome 8p21.3-p22 region (Accession No. AB020858). These results indicate that the FGF-20 gene, located on human chromosome 8p21.3-p22, consists of three exons. Compared with the nucleotide sequence of FGF-20 cDNA determined in this study, one nucleotide deletion and one nucleotide substitution in the putative coding region were identified in human genome sequence AB020858.

Alternative Splicing↗

PubMed2000

Antiplatelet mechanisms of TA-993 and its metabolite MB3 in ADP-induced platelet aggregation.

We investigated the antiplatelet mechanisms of TA-993 [(-)-cis-3-acetoxy-5-(2-(dimethylamino)ethyl)-2, 3-dihydro-8-methyl-2-(4-methylphenyl)-1,5-benzothiazepin-4(5H)-one maleate] and its metabolite MB3 (deacetyl and N-monomethyl TA-993) in human platelets stimulated by ADP in vitro. TA-993 and MB3 concentration-dependently inhibited fibrinogen binding to the ADP-stimulated platelets as well as inhibiting platelet aggregation. The antiplatelet effect of MB3 was about 300 times more potent than those of TA-993 and a glycoprotein IIb/IIIa receptor antagonist, Arg-Gly-Asp-Ser (RGDS). Aggregation of ADP-treated fixed platelets caused by the addition of fibrinogen was inhibited by RGDS but not by TA-993 and MB3. TA-993 and MB3 inhibited ADP-induced polymerization of actin filaments. Neither TA-993 nor MB3 affected cyclic AMP and cyclic GMP levels in resting platelets, and nor suppressed the increase in intracellular Ca(2+) concentration induced by ADP. These results suggest that the antiplatelet mechanisms of TA-993 and MB3 may involve inactivation of glycoprotein IIb/IIIa receptors via inhibition of the polymerization of actin.

Actins↗

PubMed2000

Developmental changes in the spatial expression of genes involved in myosin function in Dictyostelium.

We analyzed the spatial expression patterns of the genes involved in myosin function by in situ hybridization at the tipped aggregate and early culmination stages of Dictyostelium. Myosin heavy chain II mRNA was enriched in the anterior prestalk region of the tipped aggregates, whereas it disappeared from there and began to appear in both upper and lower cups of the early culminants. Similarly, mRNAs for essential light chain, regulatory light chain, myosin light chain kinase A, and myosin heavy chain kinase C were enriched in the prestalk region of the tipped aggregates. However, expression of these genes was distinctively regulated in the early culminants. These findings suggest the existence of mechanisms responsible for the expression of particular genes.

Animals↗

PubMed2000

Effects of imidapril and captopril on streptozotocin-induced diabetic nephropathy in mice.

We investigated whether the prevention of the development of diabetic nephropathy by angiotensin-converting enzyme inhibitors is associated with decreases in renal angiotensin-converting enzyme activity and/or blood pressure in diabetic mice. C57Bl/6 mice were injected with streptozotocin (200 mg/kg, i.v.) and randomized to receive either imidapril (1 and 5 mg/kg) or captopril (10 and 50 mg/kg) or vehicle by gavage for 28 days. Each assay was performed on 8-10 mice from each treatment. At 28 days after the start of drug treatment, imidapril and captopril significantly reduced blood pressure of the diabetic mice, and this effect of captopril was stronger than that of imidapril. On the other hand, inhibition of renal angiotensin-converting enzyme activity by imidapril was stronger than that by captopril. Imidapril and captopril dose-dependently inhibited urinary albumin excretion to similar extents, but they failed to inhibit the renal hypertrophy and elevation of creatinine clearance. Total renal angiotensin-converting enzyme activity was significantly reduced in diabetic mice, but immunohistochemical localization of angiotensin-converting enzyme was intensive in the vasculature and glomeruli of the diabetic kidney. In conclusion, both effects on blood pressure and angiotensin-converting enzyme activity may be involved in the prevention of development of diabetic nephropathy by imidapril and captopril in streptozotocin-induced diabetic mice. The data suggest that the degrees of contribution of their effects on blood pressure and renal angiotensin-converting enzyme activity to the inhibition of urinary albumin excretion may be different between the two angiotensin-converting enzyme inhibitors.

Albuminuria↗

PubMed2000

Molecular cloning and genomic structure of human frizzled-3 at chromosome 8p21.

WNT receptors encoded by the Frizzled genes are implicated in carcinogenesis as well as in embryonic development. Human Frizzled-3 (FZD3) gene, encoding seven-transmembrane receptor with the N-terminal cysteine-rich domain, has been cloned and characterized. Expression of the FZD3 mRNAs was investigated by using three FZD3 specific probes: HF3S1, corresponding to the 5'-UTR and a part of the coding region; HF3S2, corresponding to a part of the coding region; HF3S3, corresponding to the 3'-UTR. HF3S1 and HF3S2 hybridized to the 14.0-, 9.0-, 4.0- and 1.8-kb FZD3 mRNA, while HF3S3 hybridized to the 14.0-, 9.0-, and 4.0-kb FZD3 mRNA. The 14. 0-kb FZD3 mRNA was the major transcript in fetal brain and adult cerebellum, while the 1.8-kb FZD3 mRNA was the major transcript in adult pancreas, and many cancer cell lines examined. The 1.8-kb FZD3 mRNA, alternatively polyadenylated by the internal AATAAA signal in the coding region, is predicted to encode the truncated FZD3 protein lacking the region through the second extracellular loop to the C-terminal tail, and might function as the transmembrane-type antagonist for WNTs. The FZD3 gene consists of 8 exons, and has been mapped to human chromosome 8p21.

Adenosine Monophosphate↗

PubMed2000

Molecular cloning and genomic structure of the betaTRCP2 gene on chromosome 5q35.1.

Beta-catenin, IkappaBalpha, and HIV Vpu are recruited to the ubiquitin-proteasome degradation pathway by betaTRCP, one of the components of the ubiquitin ligase complex. betaTRCP2, a related gene of betaTRCP, was cloned and characterized. Three isoforms, betaTRCP2A, betaTRCP2B, and betaTRCP2C, were identified. All of these betaTRCP2 isoforms consist of an F-box and seven WD repeats. Human betaTRCP2A shows 86% total amino acid identity with human betaTRCP. betaTRCP2 mRNA of 4.5 kb in size was detected almost ubiquitously. Sequence analyses on betaTRCP2 genomic clones revealed that the betaTRCP2 gene consists of at least 14 exons. Exons 1 and 4-14 are shared among all betaTRCP2 isoforms. betaTRCP2A of 508 amino acids lacks exons 2 and 3, betaTRCP2B of 529 amino acids contains exon 3, and betaTRCP2C of 542 amino acids contains exon 2. These results indicate that three betaTRCP2 isoforms are transcribed due to alternative splicing. The betaTRCP2 gene has been mapped to human chromosome 5q35.1 by fluorescence in situ hybridization.

Amino Acid Sequence↗

PubMed2000

Genetic polymorphisms of human melatonin 1b receptor gene in circadian rhythm sleep disorders and controls.

Recent studies suggest that melatonin 1b (Mel1b) receptor, as well as melatonin 1a (Mel1a) receptor, is involved in the modulation of circadian rhythms in mammals. Mutational analysis was performed in the entire coding region of the human Mel1b receptor gene using genomic DNA from sleep disorder subjects. We have identified two missense mutations, G24E and L66F. However, neither is likely to be associated with sleep disorders in our study population. One of the subjects with non-24-h sleep-wake syndrome carries missense mutations in both the Mel1a and Mel1b receptor genes.

Adult↗

PubMed2000

Important role of local angiotensin II activity mediated via type 1 receptor in the pathogenesis of cardiovascular inflammatory changes induced by chronic blockade of nitric oxide synthesis in rats.

BACKGROUND: The chronic inhibition of NO synthesis by N(omega)-nitro-L-arginine methyl ester (L-NAME) upregulates the cardiovascular tissue angiotensin II (Ang II)-generating system and induces cardiovascular inflammatory changes in rats. METHODS AND RESULTS: We used a rat model to investigate the role of local Ang II activity in the pathogenesis of such inflammatory changes. Marked increases in monocyte infiltration into coronary vessels and myocardial interstitial areas, monocyte chemoattractant protein-1 (MCP-1) expression, and nuclear factor-kappaB (NF-kappaB, an important redox-sensitive transcriptional factor that induces MCP-1) activity were observed on day 3 of L-NAME administration. Along with these changes, vascular superoxide anion production was also increased. Treatment with an Ang II type 1 receptor antagonist or with a thiol-containing antioxidant, N-acetylcysteine, prevented all of these changes. CONCLUSIONS: Increased Ang II activity mediated via the type 1 receptor may thus be important in the pathogenesis of early cardiovascular inflammatory changes in this model. Endothelium-derived NO may decrease MCP-1 production and oxidative stress-sensitive signals by suppressing localized activity of Ang II.

Angiotensin II↗

PubMed2000

Angiotensin-converting enzyme inhibitor prevents plasminogen activator inhibitor-1 expression in a rat model with cardiovascular remodeling induced by chronic inhibition of nitric oxide synthesis.

Plasminogen activator inhibitor-1 (PAI-1) may participate in the development of cardiovascular remodeling by inhibiting extracellular matrix turnover and fibrinolysis. However, little is known about physiological regulators of PAI-1 in vivo. Angiotensin II has been shown to stimulate PAI-1 in vitro. We previously reported that long-term inhibition of nitric oxide (NO) synthesis with Nomega-nitro-L-arginine methyl ester (L-NAME) causes cardiovascular remodeling (vascular medial thickening and fibrosis) associated with increased tissue angiotensin-converting enzyme (ACE) activity. In the present study, we examined whether treatment with an ACE inhibitor modulates the cardiovascular PAI-1 expression in this model in vivo. Wistar-Kyoto rats were treated with either no drugs, L-NAME (100 mg/kg x day), or L-NAME plus the ACE inhibitor imidapril (20 mg/kg day). Marked increases in PAI-1 mRNA and protein levels in the aorta and left ventricle were observed after the first and fourth weeks of PAI-1 treatment. PAI-1 immunoreactivity was increased in the endothelium and the media of the aorta and coronary arteries after treatment of L-NAME. This increase in PAI-1 levels was associated with an increase in ACE activity of the aorta and left ventricle. ACE inhibition with imidapril significantly prevented both the increases in PAI-1 levels and the development of cardiovascular remodeling. These findings suggest that the local renin-angiotensin system regulates PAI-1 expression, and that the increased PAI-1 levels may contribute to the cardiovascular remodeling in this model.

Angiotensin-Converting Enzyme Inhibitors↗

PubMed2000

Ischemic hepatitis induced by mesenteric volvulus in a patient with chronic obstructive lung disease.

A 66-year-old man with chronic obstructive lung disease was admitted to our hospital, presenting with mesenteric volvulus and mild liver injury. A superior mesenteric angiogram revealed that the arteries supplying the small intestine were twisted in the arterial phase, while the portal vein was not visualized in the late phase. A celiac angiogram demonstrated that portal blood flow from the splenic venous return was maintained. The patient's symptoms had almost resolved the day after admission, and his serum transaminases level had gradually decreased to normal with conservative therapy. A superior mesenteric angiogram on the 13th hospital day showed a normal arteriogram and the portal vein demonstrated blood flow from the superior mesenteric vein. Liver biopsy revealed hemorrhagic necrosis around the central veins, which was compatible with ischemic hepatitis. Since the patient's O2 saturation level on admission was not low enough to have caused ischemic hepatitis by itself, we suspect that a sudden decrease in portal blood flow was the additional factor that allowed the threshold for the initiation of ischemic liver damage to be reached.

Aged↗