Biomedical subjects

Itaru Moro

Publications and source records attributed to Itaru Moro.

9 recordsLinked to original sources

PubMed2004

Age-dependent decrease of polymeric Ig receptor expression and IgA elevation in ddY mice: a possible cause of IgA nephropathy.

Individual animals in the closed colony population of ddY mice were analyzed to clarify the major cause of age-dependent elevation of serum IgA and the appearance of human IgA nephropathy (IgAN)-like symptoms. Based on the serum IgA levels, the mice were classified into two subgroups. One was a high serum IgA group with some manifestations of IgAN through aging (ddY(High)), and the other was a normal serum IgA group without IgAN (ddY(Norm)). The ratio of urinary IgA to serum IgA was significantly reduced in ddY(High) mice, suggesting an impaired IgA clearance via secretion through the epithelial barrier. The actual clearance rate of the intravenously injected dimeric IgA in ddY(High) mice was found to be slower than that in ddY(Norm) mice. Furthermore, we found that the polymeric Ig receptors (pIgRs) that mediate transcytosis of IgA were poorly expressed in the glomeruli as well as in the intestine of ddY(High) mice, whereas the pIgRs were more abundantly expressed in ddY(Norm) mice. In addition, the comparative study using polymerase chain reaction showed that decreased pIgR expression occurred at the transcriptional level in the ddY(High) population. Taken together, these results suggest that a systemic defect in pIgR expression may result in impaired IgA secretion and accumulation of IgA in the serum of ddY(High) mice. The age-dependent changes of pIgR expression in the dimeric IgA secretion sites of ddY(High) mice suggest a possible cause for the elevation of serum IgA level and the pathogenesis of IgAN-like disease.

Aging↗

PubMed2004

Endoplasmic reticulum resident, immunoglobulin joining chain, can be secreted by perturbation of the calcium concentration in the endoplasmic reticulum.

We established a transient human joining (J)-chain gene expression system in the baby hamster kidney (BHK) cell. The J-chain was detected as a 29-kDa single band on Western blotting. Immunofluorescent staining of the transfectant revealed an exclusive localization of the J-chain in the endoplasmic reticulum (ER). Intracellular transport experiment revealed that incubating conditions favorable for vesicular stomatitis virus glycoprotein (VSV-G) transport did not allow the J-chain to exit from the ER. Analysis of glycosylation status of the J-chain in the transfectant was examined by tunicamycin treatment, endoglycosidase H digestion, and also by treatment with brefeldin A. It was found that an N-glycosylation consensus site of the J-chain was functional, and intracellular J-chain was endoglycosidase H sensitive. These results indicate that, in the absence of any immunoglobulin molecules, J-chain localizes exclusively in the ER. We also tested whether the J-chain could be exported from the ER by perturbing the Ca2+ concentration in the ER. Cultivation of the J-chain transfectant in the presence of ionomycin resulted in the time-dependent secretion of the J-chain. The secreted J-chain was modified by the Golgi resident glycosylation enzymes, indicating that the secreted J-chain passed through the normal exocytic pathway.

Animals↗

PubMed2004

Multiple cleavage sites for polymeric immunoglobulin receptor.

Human polymeric immunoglobulin receptor (pIgR) was expressed in baby hamster kidney (BHK) cells using a recombinant vaccinia virus transfection system. Cleavage of pIgR on the cell surface was partially inhibited by the proteinase inhibitor, leupeptin. We addressed the question whether some particular regions of pIgR could affect the efficient cleavage of this molecule, with the following results: (1) a mutant lacking the entire cytoplasmic region resulted in release of secretory component (SC) into the culture supernatant much faster than wild-type; (2) a pIgR mutant lacking the entire extracellular domain 6, the region containing the susceptible cleavage sites, could be cleaved and released as a mutant SC. The transport kinetics of this mutant between endoplasmic reticulum (ER) and Golgi or Golgi and the cell surface was equivalent to wild-type pIgR. Our results indicate that although the main cleavage site is in domain 6, at least one other cleavage site may exist.

Animals↗

PubMed2003

Telomerase activity in pituitary adenomas: significance of telomerase expression in predicting pituitary adenoma recurrence.

Clinical and histopathological evaluations are inadequate for assessing biological aggressiveness and regrowth potential in benign pituitary adenomas. To develop reliable and prognostically informative means of predicting behavior remains an intractable problem. Telomerase, a reverse transcriptase that extends telomere length, may facilitate tumorigenesis and tumor immortality. In the present study, we investigated the telomerase activity of pituitary adenomas, and attempted to assess the value of telomerase expression for predicting their clinical course. In total, 31 (30 patients) benign pituitary adenoma samples including 8 recurrent adenomas were studied. Telomerase expression was evaluated by polymerase chain reaction (PCR)-based telomeric repeat amplification protocol (TRAP) assay and telomerase activity levels were quantitated by improved PCR enzyme-linked immunosorbent assay (ELISA). The data were analyzed in relation to clinical course which was reviewed at 4-5.5 years (median follow-up time, 52.5 months) after surgery. The relative values of the telomerase expression for predicting the clinical course were compared with the MIB-1 antigen-based proliferative cell index (PCI) and p53 immunoreactivity which have recently been suggested to correlate with aggressive behavior in pituitary adenomas. Overall, telomerase expression was detected in 13% of the adenomas (4 tumor tissues, 3 patients). These adenomas comprised large, invasive, and functioning adenomas. The number of telomerase-positive adenomas was small; however, the PCI was higher in cases with telomerase expression (4 tumor tissues; mean, 4.2 +/- 2.4%) than in those without it (27 tumor tissues; 1.4 +/- 1.3%) (p = 0.01). One tumor with detectable telomerase expression, which did not undergo additional pharmacological or radiotherapeutic intervention after first surgery, recurred rapidly despite gross total surgical resection, although the PCI of both the primary and recurrent adenomas was not high. Detection of telomerase expression may represent an additional useful means of identifying aggressive behavior, complementing the histopathological evaluation of benign-appearing pituitary adenomas.

Adenoma↗

PubMed2002

Prediction of clinical course of diffusely infiltrating astrocytomas from telomerase expression and quantitated activity level.

Telomerase, one of the reverse transcriptases that extend telomere length, has been suggested to facilitate tumorigenesis and tumor immortality. Little is yet known, however, concerning the clinical significance of telomerase expression in brain tumors. We found in the present study that telomerase expression may contribute to malignant progression and can be an important indicator of high grade diffusely infiltrating astrocytomas, and its quantitated activity level reflects their growth potential. Telomerase expression and its quantitated activity level are also a good predictor of clinical course as compared with other biological markers and clinical factors.

Adolescent↗

PubMed2002

Cloning and expression of the turtle (Trachemys scripta) immunoglobulin joining (J)-chain cDNA.

The J-chain protein is a M(r) 15000 polypeptide associated with polymeric IgA and IgM. The complete cDNA sequences of human, mouse, cow, brushtail possum, chicken and frog J chains have been previously reported, but nothing is known about the cDNA and amino acid sequences of reptilian J chain. Here, we determined a turtle J-chain cDNA sequence by RT-PCR and RACE, and examined J-chain mRNA and protein expression by Northern blotting and immunohistochemistry. This turtle J-chain cDNA was 1934 bp and had an open reading frame of 477 nucleotides, encoding 159 amino acids. The mature J-chain protein is composed of 137 amino acids, M(r) approximately 15000. The deduced amino acid sequence of the turtle J chain was highly homologous to that of human (60%), mouse (61%), cow (60%), rabbit (60%), chicken (69%), brushtail possum (65%), Rana catesbeiana (47%) and Xenopus laevis (58%). Eight cysteine residues were located at the same positions as in these other species, with the exception of X. laevis. PROSITE database analysis indicated the presence of two N-glycosylation sites in turtle, one of which was novel. Northern blot analysis revealed that turtle J-chain mRNA was expressed in lung, stomach, spleen and intestine. In addition, immunohistochemistry showed J-chain-positive plasma cells in the intestine and spleen. These results suggest the presence of a mucosal immune system mainly composed of J-chain-containing Ig in the turtle.

Amino Acid Sequence↗

PubMed2002

Uncommon dermoid cyst presented in the mandible possibly originating from embryonic epithelial remnants.

A case of an intraosseous dermoid cyst that had developed in the mandible of a 29-year-old-male is reported. The patient was admitted to our dental clinic complaining of pain in the right molar area of the mandible. The patient had no particular history of the present illness. A radiographic examination revealed diffuse bone absorption in the right molar area. A biopsy showed the lesion to be an intraosseous dermoid cyst which was surgically enucleated. Microscopic examination of the excised tissue showed it to be well circumscribed with fibrous tissues, and the cystic space lined by keratinized epithelium. In addition, sweat glands and hair follicle-like skin appendages were identified in the cystic wall, where a daughter cyst was also found. We suggested that this uncommon cyst had developed in the mandible, as a result of embryonic epithelium migration. The patient remained in good health during the three year follow-up.

Adult↗

PubMed2002

Cloning of the chicken immunoglobulin joining (J)-chain gene and characterization of its promoter region.

Three overlapping genomic clones of the chicken immunoglobulin joining (J) chain were isolated and then characterized using restriction enzyme analysis, Southern blot analysis with cDNA probes, and DNA sequencing. The gene consisted of four exons separated by a 2.6-kb intron 1, a 0.9-kb intron 2, and a 0.5-kb intron 3. A transcriptional initiation site was identified by a primer extension method using mRNA and cDNA, indicating that exon 1 was 86 bp encoding 20 amino acid residues. A TATA box was positioned at 29 approximately 25 bp upstream of exon 1. Exons, 2, and 3 consisted of 133 bp and 81 bp, encoding 43 and 26 amino acid residues of the mature protein, respectively. Exon 4 consisted of 202 bp encoding 66 amino acid residues and 1.2 kb of untranslated sequence. Deletion mutants of a 4.1-kb genomic fragment containing exon 1 showed high levels of promoter activities when examined in luciferase reporter assays following transfection into the DT-40 chicken B-cell line. These results suggest that the chicken J-chain gene consists of four exons and three introns and that the transcriptional regulatory elements may be present within 3.8 kb upstream of exon 1.

Amino Acid Sequence↗

PubMed2002

Overexpression of the aryl hydrocarbon receptor (AhR) accelerates the cell proliferation of A549 cells.

The arylhydrocarbon receptor (AhR) is a ligand-activated transcription factor that mediates a spectrum of toxic and biological effects of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) and related compounds. Although the physiological ligand for the AhR has not yet been identified, several reports have suggested that the AhR may play important roles not only in the regulation of xenobiotic metabolism but also in the maintenance of homeostatic functions [Singh et al. (1996) Arch. Biochem. Biophys. 329, 47-55; Crawford et al. (1997) Mol. Pharmacol. 52, 921-927; Chang et al. (1998) Mol. Cell. Biol. 18, 525-535]. Several lines of evidence suggest that one of the possible physiological roles of the AhR is regulation of cell proliferation. In this study, we first showed that treatment of A549 cells with the AhR agonist stimulates cell proliferation. The effect was antagonized by co-treatment with alpha-naphthoflavone. To obtain direct evidence that the AhR regulates cell proliferation, we isolated the clones that overexpress the AhR. These clones grow faster than control cells, and the rate of growth is proportional to the amount of the AhR. Cell cycle analysis revealed that the acceleration of cell growth by overexpression of the AhR is most probably due to shortening of the late M to S phases. Studies on the expression profiles of cell cycle regulators showed that the AhR or AhR ligand induces the expression of DP2, PCNA, and RFC38. DP2 is the transcription factor that forms the functional dimer with E2F and regulates the expression of several genes involved in DNA synthesis. Interestingly, both PCNA and RFC38 are target genes of E2F and the DP complex. Also, both of these factors are involved in regulating DNA polymerase delta activity. E2F activity was substantially increased in both the AhR-overexpressing cells and the AhR-agonist treated cells, suggesting that AhR-activated E2F/DP2 may induce the expression of PCNA and RFC38 and subsequent DNA synthesis. Down-regulation of the expression of the Arnt by RNAi diminished the effects of the AhR on the cell proliferation of the A549 cells. Consequently, we conclude that the AhR, presumably in collaboration with the Arnt, activates the DNA synthesis and the subsequent cell proliferation in A549 cells.

Cell Division↗