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Biomedical subjects

H Sakagami

Publications and source records attributed to H Sakagami.

At least 55 records · Page 3Linked to original sources
PubMed1999

Localization of mRNAs for synaptojanin isoforms in the brain of developing and mature rats.

The localization of mRNAs for synaptojanin 1 and 2, inositol 5-phosphatases, in the brain was examined by in situ hybridization histochemistry. Synaptojanin 1 mRNA was detected in almost all neurons of the central nervous system throughout developing and mature stages, although its splicing variant (synaptojanin 1-p145-I) mRNA was expressed dominantly in forebrain and cerebellar cortex. Synaptojanin 2 mRNA was first detected in neurons of the olfactory bulb, the cerebral cortex, the hippocampus, and the cerebellar cortex on early postnatal days. As the postnatal development proceeded, the expression signal was evident in the white matters, presumptive oligodendrocytes, with the clear expression remaining in neurons of the olfactory tubercle, hippocampal pyramidal cells and cerebellar Purkinje cells.

Animals↗
PubMed1999

Immunological evidence that the beta isoform of Ca2+/calmodulin-dependent protein kinase IV is a cerebellar granule cell-specific product of the CaM kinase IV gene.

Ca2+/calmodulin-dependent protein kinase IV (CaM kinase IV) exists as two monomeric isoforms, alpha and beta. In this study, we raised an antibody against the beta isoform and provided immunohistochemical evidence for specific expression of the beta isoform in cerebellar granule cells as a single gene-derived translational product distinct from the alpha isoform. Immunohistochemical examination showed that the beta-immunoreactivity was confined to the nuclei of the cerebellar granule cells, in contrast to the more widespread immunoreactivity for the alpha isoform in both nuclei and cytoplasm of the cerebellar granule cells and many other neurons with dominant nuclear localization. In developing cerebella, the beta-immunoreactivity gradually appeared in the internal granule cells during the postnatal 2nd and 3rd weeks, while the alpha-immunoreactivity had already appeared in the internal granule cells in the 1st postnatal week. Unlike the alpha isoform, beta-immunoreactivity was not detected in the Purkinje cells at any developmental stages. The differential expression of the alpha and beta isoforms suggests that each isoform may be involved in different cerebellar functions.

Aging↗
PubMed1999

Differences in androgen-dependent induction of mk1, true tissue kallikrein in C3H/HeN and ICR mouse submandibular gland.

Androgen-dependent induction of mk1, true tissue kallikrein, in submandibular gland was studied in C3H/HeN and ICR mice and their F1 progeny. By injection of 5alpha-dihydrotestosterone (DHT), total esteroproteinase activities of female mice were increased to the level of male mice in both C3H/HeN and ICR strains. The mk1 content measured by the radioimmunoassay with anti-mk1 antiserum was decreased in ICR mice, but markedly increased in C3H/HeN mice after DHT injection. We examined the kallikrein isozyme pattern in SMG of two strains using isoelectric focusing. Female ICR mice expressed mainly mk1, mk13 and mk22, and slight mk9. Female C3H/HeN mice expressed mk1, mk9 and pI 6.6-kallikrein. Injection of DHT did not induce any additional kallikrein isozyme in C3H/HeN mice. Furthermore, we made an F1(C3H/HeN) mouse expressing mk13 and mk22 by mating (female C3H/HeN x male ICR). F1(C3H/HeN); these mice showed an androgen response similar to that observed in the ICR mice: mk1 induction in F1(C3H/HeN) mice was decreased by injection of DHT. We suggest the possibility that androgen-dependent mk1 biosynthesis might interact with the expression of other kallikrein isozymes.

Androgens↗
PubMed1999

Prevention of reactive oxygen-induced endothelial cell injury by blocking its process.

Endothelial cell (EC) injury induced by reactive oxygen species (ROS) was investigated and effects of Ca(2+) channel blockers, agents which elevate intracellular cAMP levels ([cAMP](i)), and protein kinase inhibitors on H(2)O(2)-induced EC injury were analyzed using human umbilical vein EC cultures. Exposure to H(2)O(2) increased intracellular Ca(2+) levels and decreased [cAMP](i). Ca(2+) channel blockers, [cAMP](i)-elevating agents, and protein kinase inhibitors significantly inhibited H(2)O(2)-induced EC injury. Data suggest that H(2)O(2)-induced EC injury is mediated by extracellular Ca(2+) influx, intracellular cAMP efflux, and intracellular signaling, each of which is blocked by Ca(2+) channel blockers, [cAMP](i)-elevating agents, or protein kinase inhibitors. It is suggested that ischemia/reperfusion injury induced by ROS may be prevented by Ca(2+) channel blockers, [cAMP](i)-elevating agents, and protein kinase inhibitors.

1-Methyl-3-isobutylxanthine↗
PubMed1999

Thyroid hormone (3,5,3'-triido-L-thyronine) masking/inversion of stimulatory effect of androgen on expression of mk1, a true tissue kallikrein, in the mouse submandibular gland.

We studied hormonal regulation of the expression of mkl, a true tissue kallikrein, in the submandibular gland (SMG) of ICR, C3H/ HeN, and F1 (mice from male C3H/HeN x female ICR and in the ones from male ICR x female C3H/HeN). In these mouse strains, mk1 was low in content in males, abundant in females, and increased remarkably by castration of males. In the case of ICR and both F1 mice, injection of 5alpha-dihydrotestosterone (DHT) reduced the mkl level of castrated and female mice. However, the mkl content in female C3H/ HeN mice (or castrated C3H/HeN) was further increased by DHT. To investigate the real action of DHT on mk1 expression, we examined the effects of adrenoectomy/glucocorticoid (dexamethasone, Dex) administration; DHT administration into castrated and adrenoectomized mice; ovariectomy/female hormone (17beta-estradiol, progesterone) administration; and hypophysectomy/combinatory administration of DHT, Dex, and thyroid hormone (3,5,3'-triiodo-L-thyronine, T3) on the mk1 expression in the SMG of ICR mice. Adrenoectomy or ovariectomy did not change the characteristic pattern of mk1 expression in male and female ICR mice. In hypophysectomized (Hypox) ICR male mice, the mk1 content was increased to the same level as in normal ICR females, and DHT administration into the Hypox mice further increased the mk1 level. However, combinatory administration of DHT + T3 or of DHT + T3 + Dex into the Hypox mice lowered the mkl content to the level of normal ICR males, whereas T3 single administration had no effect. Dex single administration into the Hypox mice increased the mkl level to an even higher than that observed with DHT administration. The mk1 level in Hypox mice was not significantly changed by coadministration of Dex with T3. From these results, we conclude that 1) mk1 expression is fundamentally stimulated by androgen (DHT) as are other mk isozymes, such as mk9, mk13, mk22, and mk26 in the mouse SMG, 2) the effect (stimulatory) of DHT on mk1 expression becomes, however, inverted (inhibitory) in the presence of T3. Although the serum T3 level of C3H/HeN female (0.52 ng/ml) was not significantly different from that of C3H/HeN males or ICR mice, coadministration of T3 into C3H/HeN females with a fixed amount of DHT (20 mg/kg body weight) dose dependently repressed the DHT-induced increase in mkl expression, suggesting the lower sensitivity of C3H/HeN females to T3.

Adrenal Glands↗
PubMed1999

[Detection of drug-drug interaction by ESR spectroscopy].

Vitamin C (sodium ascorbate), gallic acid and dopamine induced apoptosis (characterized by internucleosomal DNA cleavage, nuclear fragmentation, chromatin condensation near nuclear membrane and loss of cell surface microvilli) in human promyelocytic leukemic HL-60 cells. ESR spectroscopy demonstrated the connection between the radical intensity and apoptosis-inducing activity of derivatives of these compounds. When vitamin C and gallic acid were mixed together, the radical intensity and cytotoxic activity of gallic acid was completely scavenged by one or two orders lower concentrations of vitamin C, suggesting the predominant action of vitamin C over gallic acid. When vitamin C and dopamine were mixed together, their radical intensity and apoptosis-inducing activity counteracted with each other. On the other hand, lignins significantly enhanced both the radical intensity and apoptosis-inducing activity of vitamin C. ESR spectroscopy might be applicable for the detection of drug-drug interaction.

Apoptosis↗
PubMed1999

Localization of PDK-1 mRNA in the brain of developing and adult rats.

Gene expression for 3-phosphoinositide-dependent protein kinase-1 (PDK-1) in developing and adult rat brains was examined by in situ hybridization histochemistry. In embryonic days, the mRNA was evident throughout the entire neuraxis. The expression remained evident throughout the entire gray matters until postnatal day 7, and thereafter it decreased overall in the mantle and ventricular zones except for the cerebellar Purkinje and granule cell layers, the olfactory and hippocampal neuronal layers. The pattern of this gene expression is similar to those of for protein kinase B and class I phosphoinositide 3-kinases.

3-Phosphoinositide-Dependent Protein Kinases↗
PubMed1999

Distribution and intracellular localization of a mouse homologue of Ca2+/calmodulin-dependent protein kinase Ibeta2 in the nervous system.

Ca2+/calmodulin-dependent protein kinases (CaMKs) are believed to play important roles in the development and function of the nervous system. We report here the identification and expression of mouse CaMKIbeta (mCaMKIbeta), in particular mCaMKIbeta2, an isoform of mCaMKIbeta. During embryogenesis, the mCaMKIbeta2 gene is expressed mainly in the nervous system, including brain, spinal cord, trigeminal ganglion, and retina. Within the CNS, the expression of mCaMKIbeta2 is detected in the mantle zone, but not in the ventricular zone, suggesting its possible involvement in the differentiation of neurons. In the adult brain, mCaMKIbeta2 transcripts are detected at high levels in the anterior olfactory nuclei, piriform cortex, septal nuclei, bed nuclei of the stria terminalis, hippocampal pyramidal cells, dentate granule cells, amygdala, hypothalamic nuclei, parabrachial nucleus, and nucleus of the solitary tract. The distinct gene expression pattern suggests that mCaMKIbeta2 may also be involved in different mature neuronal functions from other CaMKs. In addition, mCaMKI/beta2 proteins are localized to the cytoplasm and nuclei, but not to nucleoli, suggesting that mCaMKIbeta2 proteins might be involved in the cytoplasmic and nuclear signal transduction of the nervous system.

Amino Acid Sequence↗
PubMed1998

Rac1 is required for the formation of three germ layers during gastrulation.

The Rac1, a member of the Rho family proteins, regulates actin organization of cytoskeleton and cell adhesion. We used genetic analysis to elucidate the role of Rac1 in mouse embryonic development. The rac1 deficient embryos showed numerous cell deaths in the space between the embryonic ectoderm and endoderm at the primitive streak stage. Investigation of the primary epiblast culture isolated from rac1 deficient embryos indicated that Rac1 is involved in lamellipodia formation, cell adhesion and cell migration in vivo. These results suggest that Rac1-mediated cell adhesion is essential for the formation of three germ layers during gastrulation.

Animals↗
PubMed1998

Localization of mRNAs for CDP-diacylglycerol synthase and phosphatidylinositol synthase in the brain and retina of developing and adult rats.

CDP-diacylglycerol (CDP-DAG) synthase (CDS) is known as one of the key enzymes in the lipid synthesis including phosphoinositides (PIs) production. Phosphatidylinositol (PtdIns) synthase (PIS) catalyzes a formation of PtdIns from CDP-DAG in the PI cycle which produces several second messengers. We compared the gene expression for a presumably PI cycle specific-CDS molecule and a PIS using Northern blot analysis and in situ hybridization histochemistry in the central nervous system (CNS) and retina of developing and mature rats. Whereas no significant expression for CDS was detected during the prenatal stage in any CNS regions, PIS mRNA had already expressed on the prenatal day 15 throughout the neuroaxis including the spinal cord. During the postnatal stages, the gene expression for both CDS and PIS was detected widely in the gray matters throughout the entire brain. The expression for CDS was at higher levels in the olfactory mitral cells, the occipital cortex, the subiculum and hippocampal CA1 pyramidal cells, and the cerebellar Purkinje cells. On the other hand, the expression for PIS was at high levels in the olfactory mitral cells, the cerebral cortex, the hippocampal and dentate neuronal layer and the cerebellar Purkinje and granule cells. No significant expression for CDS or PIS was detected in the ventricular germinal zone, the cerebellar external granular layers, the mature ependyma or entire white matters. The expression for CDS and PIS decreased slightly throughout the CNS on P49. The significance of the parallel and discrepant expression patterns in terms of relative intensity between the two enzyme molecules was discussed in relation to the membrane turnover and signal transduction.

Animals↗
PubMed1998

Molecular characterization and tissue distribution of a new organic anion transporter subtype (oatp3) that transports thyroid hormones and taurocholate and comparison with oatp2.

Two complementary DNAs for the organic anion transporter subtypes oatp2 and oatp3, which transport thyroid hormones as well as taurocholate, were isolated from a rat retina cDNA library. The sequence of oatp2 is identical to that recently reported (Noé, B., Hagenbuch, B., Stieger, B., and Meier, P. J. (1997) Proc. Natl. Acad. Sci. U. S. A. 94, 10346-10350), whereas the sequence of oatp3 is novel. oatp3 consists of 670 amino acid residues and exhibits a structural architecture common to the organic anion transporter family, possessing the 12 putative membrane-spanning segments. Oocytes injected with oatp2 and oatp3 cRNAs showed taurocholate uptake in a saturable manner. The oatp2 and oatp3 cRNA-injected oocytes also showed significant uptake of both thyroxine and triiodothyronine. Northern blot and in situ analyses showed that the oatp2 mRNA was widely expressed in neuronal cells of the central nervous system, especially in the hippocampus, cerebellum, and choroid plexus as well as in the retina and liver. The oatp3 mRNA was highly expressed in the kidney and moderately abundant in the retina. This suggests that oatp2 and oatp3 are multifunctional transporters involved in the transport of thyroid hormones in the brain, retina, liver, and kidney.

Amino Acid Sequence↗
PubMed1998

A novel class II phosphoinositide 3-kinase predominantly expressed in the liver and its enhanced expression during liver regeneration.

We report herein the cloning and characterization of a novel class II phosphoinositide 3-kinase, termed PI3K-IIgamma, from the cDNA library of regenerating rat liver. This cDNA encodes a protein of 1505 amino acids with a calculated molecular mass of 170,972 Da. The amino acid sequence of PI3K-IIgamma is highly similar to those of class II PI 3-kinases, including murine Cpk-m/p170 and human HsC2-PI3K. It contains a C2 domain at the C terminus but no recognizable protein motifs at its N terminus. PI3K-IIgamma displays a restricted substrate specificity for PtdIns and PtdIns 4-P, but not for PtdIns 4,5-P2. By epitope tag immunocytochemistry, the immunoreactivity for PI3K-IIgamma is localized in the juxtanuclear Golgi region at high levels and also in the plasma and nuclear membranes at low levels. By Northern blot analysis and in situ hybridization histochemistry, PI3K-IIgamma mRNA expression is confined to the liver throughout the development with much higher expression in adult liver than in fetal liver. In addition, its expression increases during liver regeneration after partial hepatectomy with maximal expression after the growth period, suggesting that PI3K-IIgamma may function mainly in highly differentiated hepatic cells.

Adult↗
PubMed1998

Localization of the mRNAs for two isoforms of Ca2+/calmodulin-dependent protein kinase kinases in the adult rat brain.

Ca2+/calmodulin-dependent protein kinase (CaM kinase) I and IV are thought to be activated by CaM kinase kinases (CaMKK). We examined the distribution of mRNAs for two isoforms (alpha and beta) of CaMKKs in the brain by in situ hybridization histochemistry. In the adult rat brain, CaMKK alpha mRNAs are widely distributed throughout the brain, whereas CaMKK beta mRNAs are restricted to some neuronal populations, particularly the cerebellar granule cells.

Animals↗
PubMed1998

Interaction between sodium ascorbate and dopamine.

The interaction between sodium ascorbate and dopamine was investigated by three different parameters: radical intensity, prooxidant action, and cytotoxicity induction. Sodium ascorbate and dopamine produced the doublet and quartet ESR signals under alkaline conditions (pH 8.0-9.5), respectively. Addition of increasing concentrations of sodium ascorbate completely scavenged the dopamine radical and replaced the latter with its own radical. Similarly, dopamine slightly, but significantly reduced the radical intensity of sodium ascorbate. These two compounds stimulated the methionine oxidation and hydrogen peroxide generation in culture medium, but in combination, their stimulation activities were weakened. Both of these two compounds dose-dependently reduced the viable cell number of human oral squamous carcinoma HSC-4 cells, and their cytotoxic activity was significantly reduced by catalase. When these two compounds were mixed together before adding to HSC-4 cells, both of their cytotoxic activities were diminished. The present study demonstrates the interaction between sodium ascorbate and dopamine, which might modify their biological activities and generation of nerve disorders such as Parkinson's disease.

Amino Acids↗
PubMed1998

Differential localization of mRNAs for mammalian trps, presumptive capacitative calcium entry channels, in the adult mouse brain.

Mammalian homologues for Drosophila trp are likely to be candidates for capacitative calcium entry channels. By in situ hybridization histochemistry, we have demonstrated that the mRNAs for four species of the mouse homologues (Mtrps-1, -3, -4, -6) were differentially expressed in the adult mouse brain. Mtrp-1 mRNA was expressed widely throughout the gray matters, while the expression for Mtrp-3 was dominant in the cerebellar Purkinje cells, the olfactory mitral cells and the striatal large-sized intrinsic neurons. Mtrp-4 mRNA was evident in the olfactory bulb, the septum, the hippocampal neuronal layers, and the cerebellar granule cell layer, while the expression for Mtrp-6 was rather confined to the dentate granule cell layer. Their differential localization suggests that the individual homologues exert their functions in region-specific and neuron-specific manners in the calcium signaling.

Animals↗