Biomedical subjects

Hisako Fujimura

Publications and source records attributed to Hisako Fujimura.

6 recordsLinked to original sources

PubMed2005

Gene expression profiling in streptozotocin treated mouse liver using DNA microarray.

Streptozotocin (SZ) is known to exert toxic effects not only on pancreatic islet beta cells but also on other organs including liver. For analyzing changes in genes expression associated with SZ toxicity, we performed DNA microarray analyses on the liver obtained from SZ-treated mice. Eight-week-old male ICR mice were treated i.p. with 200 mg/kg of SZ, and the blood and liver were taken at 6, 24 and 48 h after the treatment. Labeled cRNA prepared from total RNA of the liver was hybridized to the GeneChip Murine Genome U74A V.2 (Affymetrix). The number of the probe sets, which were clearly up-regulated or down-regulated, were over 100 at 6 and 24h after the SZ-treatment, and it decreased at 48 h after the treatment. Many of the up-regulated genes were categorized into cell cycle/apoptosis related genes, immune/allergy related genes and stress response/xenobiotic metabolism related genes. On the other hand, genes related to glucose, lipid and protein metabolisms were down-regulated. These changes started prior to the elevation of the serum glucose levels, indicating the direct action of SZ on the liver rather than the secondary effect of diabetes. This may be related with the previously reported hepatic changes such as lipid peroxidation, mitochondrial swelling and inhibition of hepatocyte proliferation observed before the development of hyperglycemia.

Animals↗

PubMed2005

Morphological and gene expression analysis in mouse primary cultured hepatocytes exposed to streptozotocin.

Streptozotocin (SZ) is known to exert toxic effects not only on pancreatic islet beta cells but also on other organs including the liver. For analyzing direct effects of SZ on hepatocytes, we performed morphological analysis and DNA microarray analysis on mouse primary cultured hepatocytes. Hepatocytes were taken from non-treated Crj:CD-1(ICR) mice. The primary cultured hepatocytes were treated with SZ at concentrations of 0, 1, 3, 10, 30 and 100 mM. After the treatment for about 6 or 24h, cell survival assay using tetrazolium salt (WST-1), light microscopic/electron microscopic analysis and gene expression analysis were performed. For the gene expression analysis, target (labeled cRNA) prepared from total RNA of the hepatocytes was hybridized to the GeneChip Murine Genome U74A V.2 (Affymetrix). The signal intensity calculation and scaling were performed using Microarray Suite Software Ver 5.0. IC50 of the cell survival assay was around 62 mM at 6 h exposure and 7 mM at 24 h exposure. Marked chromatin margination was observed in nuclei of the hepatocytes treated with SZ at concentrations of 3 or 10mM. Gene expression analysis revealed similar expression changes to those of in vivo, i.e. up-regulation in cell proliferation/ apoptosis related genes, and down-regulation of lipid metabolism related genes. These results potently supported the hypothesis that many of the hepatic alteration including histopathological and gene expression changes are induced by direct effect of SZ rather than by the secondary effect of the hyperglycemia or hypoinsulinemia.

Animals↗

PubMed2004

Hepatic changes in the acute phase of streptozotocin (SZ)-induced diabetes in mice.

We have reported the streptozotocin (SZ)-induced hepatic lesions in the subacute phase (4 to 12 weeks after the treatment), which are characterized by appearance of oncocytic hepatocytes, cytomegalic hepatocytes and bile duct hyperplasia. In this study, we focused on the acute phase (6 to 48 hours after the treatment) of the SZ-induced hepatic lesions of mice to clarify the onset of the hepatic alterations, especially before the induction of hyperglycemia. Livers were taken from 8-week-old Crj:CD-1 (ICR) male mice at 6, 12, 24, 36 and 48 hours after the 200 mg/kg b.w. of SZ-injection. SZ-induced hyperglycemia was noted at 36 and 48 hours after the treatment, but the hepatic changes including lipid peroxidation, mitochondrial swelling, peroxisome proliferation and inhibition of hepatocyte proliferation occurred before the elevation of the serum glucose levels. The present findings indicate the direct effects of SZ on hepatocytes rather than the secondary effects of diabetes, and certain correlations between the hepatocytic changes in the acute phase and those in the subacute one. In addition, ulcer and submucosal edema of the gallbladder were observed at 36 or 48 hours after the SZ-treatment, which can be a novel finding in SZ-treated animal.

Acute Disease↗

PubMed2003

The novel dominant mutation Dspd leads to a severe spermiogenesis defect in mice.

Spermiogenesis is a complex process that is regulated by a plethora of genes and interactions between germ and somatic cells. Here we report a novel mutant mouse strain that carries a transgene insertional/translocational mutation and exhibits dominant male sterility. We named the mutation dominant spermiogenesis defect (Dspd). In the testes of Dspd mutant mice, spermatids detached from the seminiferous epithelium at different steps of the differentiation process before the completion of spermiogenesis. Microinsemination using spermatids collected from the mutant testes resulted in the birth of normal offspring. These observations indicate that the major cause of Dspd infertility is (are) a defect(s) in the Sertoli cell-spermatid interaction or communication in the seminiferous tubules. Fluorescent in situ hybridization (FISH) analysis revealed a translocation between chromosomes 7F and 14C at the transgene insertion site. The deletion of a genomic region of chromosome 7F greater than 1 megabase and containing at least six genes (Cttn, Fadd, Fgf3, Fgf4, Fgf15, and Ccnd1) was associated with the translocation. Cttn encodes the actin-binding protein cortactin. Immunohistochemical analysis revealed localization of cortactin beside elongated spermatids in wild-type testes; abnormality of cortactin localization was found in mutant testes. These data suggest an important role of cortactin in Sertoli cell-spermatid interactions and in the Dspd phenotype.

Animals↗

PubMed2003

Na+/Ca2+ exchanger-deficient mice have disorganized myofibrils and swollen mitochondria in cardiomyocytes.

The Na(+)/Ca(2+) exchanger (NCX1) plays a key role in maintaining Ca(2+) homeostasis in cardiomyocytes. Disruption of Ncx1 gene in mice results in embryonic lethality between embryonic day 9 and 10, with the mice lacking spontaneous heartbeats. We examined the mechanism of lack of heartbeats in Ncx1-deficient mice. Ultrastructual analysis demonstrated that Ncx1-deficient mice showed severe disorganization of myofibrils, a lack of Z-lines and swelling of mitochondria in cardiomyocytes. However, the expressions of cardiac-specific genes including transcription factor genes and contractile protein genes were not changed in Ncx1-deficient mice. Abnormal Ca(2+) handling itself or the lack of heartbeats due to the inactivation of Ncx1 gene may cause the disorganization of myofibrillogenesis. Although NCX1 protein levels were decreased in heterozygous mice, there were no changes in NCX2 and NCX3 protein levels between wild type and heterozygous mice.

Animals↗

PubMed2002

Tissue-specific regulation of expression and activity of P-glycoprotein in adjuvant arthritis rats.

Cyclosporine A and steroids are effective against rheumatoid arthritis and also known as substrates of P-glycoprotein (P-gp). We investigated the effect of arthritis on the hepatic and intestinal P-gp activity in rats, and substantiated the expression level of the hepatic P-gp. Doxorubicin was used as a P-gp substrate. Cumulative biliary excretion and intestinal exsorption of doxorubicin following intravenous administration were compared between adjuvant arthritis (AA) and normal rats. Intestinal P-gp activity was also investigated by intestinal everted sac method, and hepatic P-gp was detected by FITC-labeled antibody and visualized using a confocal laser microscope system. Biliary clearance of doxorubicin in AA rats was significantly decreased from that in normal rats. The expression level of the hepatic P-gp in AA rats was very low compared to normal rats, indicating down-regulation. Intestinal exsorption clearance was not different between AA and normal rats. Permeability of doxorubicin across intestinal everted sac was comparable between AA and normal rats, corresponding to in vivo study. In AA rats, hepatic P-gp activity was decreased due to the reduction of expression level, but intestinal P-gp activity was not changed. Different regulation systems may be involved in liver and intestine.

ATP Binding Cassette Transporter, Subfamily B, Mem↗