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K Nakagawara

Publications and source records attributed to K Nakagawara.

18 recordsLinked to original sources
PubMed2001

Microsatellite instability and alternative genetic pathway in intrahepatic cholangiocarcinoma.

BACKGROUND/AIMS: Intrahepatic cholangiocarcinoma (ICC) arises from intrahepatic bile duct epithelium and is the second most prevalent among primary liver cancers. The aim of this study was to clarify the mechanism of cholangiocarcinogenesis. METHODS: We studied the incidence of microsatellite instability (MSI) involving eight highly polymorphic microsatellite markers and alternations of the K-ras, p53 and mdm-2 genes in human ICC tissues. Overexpression of mdm-2 oncoprotein was also immunohistochemically studied. RESULTS: Of all 65 cases examined, K-ras gene mutation was found in three cases (4.6%) at codon 12. Analysis of p53 alterations was performed in 28 cases including 22 frozen samples and mutations were found in three cases (10.7%). Overexpression of mdm-2 protein was observed in 25 (41.7%) out of 60 cases analyzed. In 22 frozen samples, seven (31.8%) cases showed mdm-2 amplification and four (18.2%) cases revealed MSI-positive phenotype. Among the cases analyzed, all the tumors with mdm-2 amplification/overexpression harbored the wild-type p53 gene and all the microsatellite instability-positive cases were from mass-forming (MF) + periductal-infiltrating (PI) subtype. CONCLUSIONS: These results suggest that mdm-2 plays a role, which might be partially through inhibiting p53 activity, in cholangiocarcinogenesis and that M

Adult↗
PubMed1999

RhoN, a novel small GTP-binding protein expressed predominantly in neurons and hepatic stellate cells.

A cDNA encoding a novel member of the small molecular weight GTP-binding protein (small G-protein) superfamily was cloned from rat spinal cord. The deduced amino acid sequence was highly homologous with those of so-far-known Rho proteins. Rho proteins were reported to alter many important cellular functions including formation of both actin stress fibers and focal adhesions. RNA blot hybridization and in situ hybridization analyses indicated that the novel small G-protein is expressed specifically in neurons in the brain and spinal cord and also in hepatic stellate cells. Based on the sequence similarity and neuron-specific expression in the brain, this protein was named RhoN. Unlike classical Rho proteins, RhoN was not susceptible to the ADP-ribosylation reaction by C3 botulinum toxin. Accordingly, RhoN seemed to be specifically involved in neuronal and hepatic functions as a C3 toxin-insensitive member of the Rho subfamily. Then, a mouse genomic DNA segment containing the RhoN gene was cloned. The locus was mapped on the mouse chromosome 11C-D. The sequence data showed that the protein-coding sequence for RhoN is divided by 4 introns, and that the defined 5 exons may encode intramolecular domains serving for different functions.

Adenosine Diphosphate Ribose↗
PubMed1999

Telomerase and proliferative activity in placenta from women with and without fetal growth restriction.

OBJECTIVE: To analyze telomerase and proliferative activity in placenta from women with and without fetal growth restriction (FGR). METHODS: Telomerase activity was analyzed in 30 first-trimester chorionic villi specimens (group A) and in 28 second- and third-trimester placenta specimens (group B) from women without FGR. Telomerase activity also was analyzed in 11 placenta specimens from women with asymmetric FGR (group C). The proliferative activity of these 69 specimens was assessed by immunohistochemical staining, using the MIB-1 monoclonal antibody. RESULTS: Telomerase activity was detected in 28 (93.3%) of 30 chorionic villi specimens and in 18 (64.3%) of 28 placenta specimens without FGR. In contrast, no telomerase activity was exhibited in the placenta specimens from any of the 11 women with asymmetric FGR by telomeric repeat amplification protocol assay. Telomerase activity also was detected by in situ telomeric repeat amplification protocol assay in trophoblastic cells from women without FGR but not in trophoblastic cells from women with asymmetric FGR. Thus, telomerase activity was detected significantly more often in groups A and B than in group C (P < .01). The rate of proliferative activity, evident as positive MIB-1 staining in trophoblastic cells, in groups A and B (28.1+/-1.7% and 7.0 +/-2.9%, respectively) was significantly higher than that in group C (1.9+/-0.6%; P < .01). CONCLUSION: Telomerase and proliferative activity were minimal in placenta from women with asymmetrical FGR, suggesting placental senescence with asymmetrical FGR.

Cell Division↗
PubMed1998

Structure and expression of mitsugumin29 gene.

Recently mitsugumin29 unique to the triad junction in skeletal muscle was identified as a novel member of the synaptophysin family; the members of this family have four transmembrane segments and are distributed on intracellular vesicles. In this study, we isolated and analyzed mouse mitsugumin29 cDNA and genomic DNA containing the gene. The mitsugumin29 gene mapped to the mouse chromosome 3 F3-H2 is closely related to the synaptophysin gene in exon-intron organization, which indicates their intimate relationship in molecular evolution. RNA blot hybridization and immunoblot analysis revealed that mitsugumin29 is expressed abundantly in skeletal muscle and at lower levels in the kidney. Immunofluorescence microscopy demonstrated that mitsugumin29 exists specifically in cytoplasmic regions of the proximal and distal tubule cells in the kidney. The results obtained may suggest that mitsugumin29 is involved in the formation of specialized endoplasmic reticulum systems in skeletal muscle and renal tubule cells.

Amino Acid Sequence↗
PubMed1998

Structural organization and chromosomal localization of the mouse tesk1 (testis-specific protein kinase 1) gene.

TESK1 (testis-specific protein kinase 1) is a protein serine-threonine kinase, containing characteristic structural features composed of an N-terminal kinase domain and a C-terminal proline-rich domain. Tesk1 mRNA is predominantly expressed in testicular germ cells, and developmental changes of expression in mouse testis suggest a role for this kinase in spermatogenesis. In the present study, we isolated and determined the overall sequence of the mouse Tesk1 gene, which spans 6.1 kilobases (kb) and contains 10 exons and 9 introns. The protein kinase domain is located in exons 1-9, while the proline-rich domain is in exons 9 and 10. The deduced 627 amino acid sequence of mouse TESK1 shows 97% and 94% identity with the rat and human TESK1, respectively. Sequence of the 5'-flanking and -untranslated region is devoid of a TATA box, but does contain several potential binding sites for transcription factors, including Sp1, AP-1, c-Myc, SRY and CREM (cyclic AMP-responsive element modulator). As CREM is implicated in the activation of several male germ cell-specific genes, it is suggested that the expression of the Tesk1 gene is under the control of CREM transcription activity. The Tesk1 gene was mapped to mouse chromosome 4A5-C1 by fluorescence in situ hybridization.

Amino Acid Sequence↗
PubMed1998

Telomerase activity in human chorionic villi and placenta determined by TRAP and in situ TRAP assay.

Telomerase activity (TA) was analysed in human chorionic villi and placenta in normal and abnormal pregnancy using the telomeric repeat amplification protocol (TRAP) and in situ TRAP assay. Twenty chorionic villi specimens and 25 placenta specimens from normal pregnancies were examined as well as placenta specimens from 10 cases of intrauterine growth retardation (IUGR; nine asymmetric and one symmetric). TA was detected in 18 of the 20 (90 per cent) chorionic villi specimens and in 18 of the 25 (72 per cent) placenta specimens from normal pregnancy. However, no or only weak TA was exhibited in the placenta specimens of the nine asymmetric IUGR cases. In situ TRAP assay detected TA in trophoblastic cells from normal pregnancy, but not in trophoblastic cells from cases of asymmetric IUGR.

Adult↗
PubMed1997

Structure, chromosomal localization and expression of mouse genes encoding type III Reg, RegIII alpha, RegIII beta, RegIII gamma.

Reg (regenerating gene), first isolated from a rat regenerating islet cDNA library, is expressed in regenerating islet beta-cells. Recently, it has been revealed that Reg and Reg-related genes constitute a multigene family, Reg family, which consists of three subtypes (type I, II, III) based on the primary structures of the encoded proteins of the genes. In mouse, type I and type II Reg genes (i.e. RegI and RegII gene) have so far been isolated. In the present study, the complete nucleotide (nt) sequences of the cDNAs and genes encoding murine type III Reg (regenerating gene product), RegIII alpha, RegIII beta and RegIII gamma were determined. RegIII alpha, RegIII beta and RegIII gamma encode 175-, 175- and 174-amino acid (aa) proteins, respectively, with 60-70% homology. All three genes are composed of six exons and five introns spanning approx. 3 kb, and exhibit distinctive structural features unique for members of the Reg gene family. All the mouse Reg genes, RegIII alpha, RegIII beta, RegIII gamma, RegI and RegII, are assigned to the adjacent site of chromosome 6C by fluorescence in situ hybridization (FISH). RegIII alpha, RegIII beta and RegIII gamma were expressed weakly in pancreas, strongly in intestinal tract, but not in hyperplastic islets, whereas both RegI and RegII were expressed in hyperplastic islets. These results suggest that genes of the mouse Reg family are derived from a common ancestor gene by several gene duplications, and have obtained divergency in expression and function in the process of genetic evolution.

Amino Acid Sequence↗
PubMed1996

Assignment of the gene for rat thromboxane receptor (Tbxa2r) to chromosome 7q11 by fluorescence in situ hybridization.

Thromboxane plays physiological and pathophysiological roles in many tissues. Recently, we cloned a cDNA for rat kidney thromboxane receptor (Tbxa2r) and showed that Tbxa2r is expressed in the renal glomerulus, vasculature, and transitional cell epithelium of renal pelvis. Here, we map the gene for this receptor (Tbxa2r) to rat chromosome 7q11 by fluorescence in situ hybridization.

Animals↗
PubMed1996

Functional analysis and chromosomal gene assignment of rat kidney prostaglandin EP3 receptor.

We have reported two isoformes of rat prostaglandin EP3 receptor with their different carboxyl-terminal tails (rEP3A and rEP3B receptors), which are derived by alternative RNA splicing, and both receptors have been shown to be localized to renal distal tubules. In the present study, we characterized the signal transduction system of rat kidney EP3 receptors either in a renal cell line mimicking renal distal tubule cells, TKC2, or in COS-7 cells by functional expression of these receptors. We also examined the chromosomal localization of the EP3 receptor gene by fluorescence in situ hybridization (FISH). In TKC2 cells, vasopressin (AVP, 10(-7) M), prostaglandin (PG) E2 (10(-7) M), or forskolin (10(-8) M) markedly stimulated cyclic AMP formation. Overexpression of the rEP3A receptor significantly attenuated the AVP-, PGE2- or forskolin-induced cyclic AMP formation, whereas there was no change with rEP3B receptor expression. On the other hand, in COS-7 cells transfected with rEP3A receptor cDNA, PGE2 (10(-7) M) did not affect cytosolic free calcium concentration ([Ca2+]i), whereas transfection of rEP3B receptor cDNA evoked PGE2-induced increases in [Ca2+]i. Moreover, we have revealed that the rEP3 receptor gene is localized to rat chromosome 2q44-45. In conclusion, rEP3A or rEP3B receptor is suggested as a mediator of the natriuretic/diuretic action of PGE2 in renal distal tubules via a decrease in cyclic AMP formation or an increase in [Ca2+]i, respectively. Information of the gene assignment of rat EP3 receptor to rat chromosome 2q44-45 is useful for further analysis of the role of EP3 receptor in genetically hypertensive rat models.

Alprostadil↗
PubMed1995

Human REG family genes are tandemly ordered in a 95-kilobase region of chromosome 2p12.

Reg, first isolated from a rat regenerating islet cDNA library, is expressed in regenerating islet beta-cells. Recently, it has been revealed that Reg and Reg-related genes constitute a multigene family, the Reg family. In human, the four REG family genes, i.e., REG 1 alpha, REG 1 beta, REG-related sequence (RS) and HIP/PAP, have so far been isolated. In this study, we analyzed YAC clones containing the four genes and performed two-color FISH to determine the map order of the genes. The human REG family genes are tandemly ordered in the 95-kbp DNA region of chromosome 2p12 as follows: 2cen-HIP/PAP-RS-REG I alpha-REG I beta-ptel.

Acute-Phase Proteins↗
PubMed1995

Assignment of CD38, the gene encoding human leukocyte antigen CD38 (ADP-ribosyl cyclase/cyclic ADP-ribose hydrolase), to chromosome 4p15.

CD38 has been used as a phenotype marker of lymphocyte differentiation. Recently, we have demonstrated that cyclic ADP-ribose can be synthesized and hydrolyzed by CD38 and acts as a second messenger in insulin secretion from pancreatic beta-cells. We have mapped the CD38 gene to human chromosome 4p15 by fluorescence in situ hybridization.

ADP-ribosyl Cyclase↗
PubMed1994

Structure and chromosomal mapping of genes for the mouse kappa-opioid receptor and an opioid receptor homologue (MOR-C).

Recent cDNA cloning studies have defined four members of the opioid receptor family, i.e., delta-, mu- and kappa-subtypes, and an opioid receptor homologue for unknown ligands. In this report, we isolated and analyzed mouse genomic DNA segments containing the kappa-opioid receptor gene and a gene for the opioid receptor homologue (designated as MOR-C). The genes are closely related each other in exon-intron organization, suggesting their evolutional relationship. Using in situ hybridization, we show that the kappa-opioid receptor gene and the MOR-C gene map to mouse chromosome 1A2-3 and 2H2-4, respectively.

Amino Acid Sequence↗
PubMed1994

Isolation, structural determination and expression of a novel reg gene, human regI beta.

We have isolated a novel human gene and cDNA encoding a member of the regI proteins, regI beta. The gene encodes a 166-amino acid protein which has 22 amino acid substitutions in comparison with the previously isolated human reg protein, regI alpha. RegI beta was expressed only in pancreas, whereas regI alpha was expressed in kidney and stomach as well as in pancreas.

Amino Acid Sequence↗
PubMed1993

Structure, chromosomal localization, and expression of mouse reg genes, reg I and reg II. A novel type of reg gene, reg II, exists in the mouse genome.

We previously identified a gene, reg (i.e. regenerating gene), in the screening of a regenerating islet-derived cDNA library of rat (Terazono, K., Yamamoto, H., Takasawa, S., Shiga, K., Yonemura, Y., Tochino, Y., and Okamoto, H. (1988) J. Biol. Chem. 263, 2111-2114), and isolated a human reg cDNA and gene (Watanabe, T., Yonekura, H., Terazono, K., Yamamoto, H., and Okamoto, H. (1990) J. Biol. Chem. 265, 7432-7439); the rat and human cDNAs encode 165- and 166-amino acid proteins, respectively. Until now, it was thought that there is a single locus for Reg protein in the mammalian genome. In this study, we isolated two distinct cDNAs and genes, one of which was a mouse homologue to rat and human reg gene, the other a novel type of reg gene. We designated them reg I and reg II, respectively. The two proteins encoded by these genes share 76% amino acid sequence identity with each other. Both genes span about 3 kilobase pairs, and the genomic organization of six exons and five introns is conserved between them. Chromosomal mapping studies indicate that the reg I gene is localized on mouse chromosome 12, whereas the reg II gene is localized on chromosome 3. By Northern blot analysis, both reg I and reg II mRNAs are detected in the normal pancreas and hyperplastic islets of aurothioglucose-treated mice, but not in the normal islets. It is remarkable that in the gallbladder reg I is expressed, but reg II is not.

Amino Acid Sequence↗
PubMedDate not supplied

Experimental cerebral ischemia in spontaneously hypertensive rats (SHR): Importance of degree of hypertension.

To study the relationship between the degree of hypertension and experimentally-induced cerebral ischemia, brain metabolites, including lactate, pyruvate and adenosine triphosphate (ATP) were determined one hour after bilateral carotid occlusion in 119 spontaneously hypertensive rats (SHR) with a variety of mean arterial pressures (MAP). Of these, 36 SHR were given antihypertensive agents for 10 weeks to reduce blood pressure prior to the experiment. There was a significant linear correlation between MAP before and either supratentorial lactate (r = 0.482, p less than 0.001) or the lactate/pyruvate ratio (r = 0.388, p less than 0.001) in the brain after carotid occlusion. An inverse correlation was observed between supratentorial lactate and either ATP (r = -0.627, p less than 0.001) or arterial PCO2 (r = -0.477, p less than 0.001) after carotid occlusion. The changes suggest that the animals with a higher MAP had a greater increase in ischemic metabolites with a decrease in ATP and a more pronounced hypocapnia after carotid occlusion. This hypocapnia is believed to be due to hyperventilation induced by cerebral ischemia. It is concluded that hypertensive rats are more susceptible to cerebral ischemia and the susceptibility is related to the degree of hypertension. By long-term lowering of the blood pressure prior to carotid occlusion, the ischemic changes are lessened in this experimental model.

Adenosine Triphosphate↗