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Biomedical subjects

M Hatanaka

Publications and source records attributed to M Hatanaka.

At least 19 recordsLinked to original sources
PubMed1992

Possible activity of acidic fibroblast growth factor as a progression factor rather than a transforming factor.

Acidic and basic fibroblast growth factors (aFGF and bFGF) are mitogens for mesoderm- and neuroectoderm-derived cells. The facts that FGF-related proteins are oncogenic and that FGFs are expressed in a variety of tumor cell lines or tumor tissues suggest the transforming activities of FGFs. To examine such an activity of aFGF, we introduced a human aFGF expression vector into two populations of Rat-1 cells; one was non-transformed (nRat-1), the other was partially-transformed (tRat-1). tRat-1 cells transfected with aFGF cDNA formed larger colonies in soft agar and produced larger and more malignant tumors in nude mice than those of parental cells. In contrast, nRat-1 cells transfected with aFGF cDNA neither formed colonies in soft agar nor produced tumors in nude mice. Our results suggest that high expression of aFGF may enhance a tumorigenic potential of Rat-1 cells rather than confer such a potential de novo.

Animals↗
PubMed1992

Phosphorylation of the Rex protein of human T-cell leukemia virus type I.

Rex protein, the posttranscriptional regulator of human T-cell leukemia virus type I (HTLV-I), is required for the control of viral structural protein expression and virus replication. Rex is a phosphoprotein found predominantly in the cell nucleolus, whose function is thought to be regulated by its nucleolar localization and phosphorylation. Therefore, we investigated the in vivo phosphorylation of Rex protein in more detail. Phosphorylation of Rex occurred in all HTLV-I-infected cell lines examined in vivo, primarily at serine residues and to a very small extent at threonine residues. Treatment of cells with 12-O-tetradecanoylphorbol-13-acetate (TPA) led to significant but transient enhancement of the incorporation of [32P]orthophosphate into Rex protein. N-terminal truncation of Rex protein abolished TPA-dependent phosphorylation. Chymotryptic digestion of phosphorylated Rex yielded two phosphopeptides. In vivo phosphorylation sites were identified as serine residues 70 and 177 and threonine residue 174. Serine 70 was a TPA-dependent phosphorylation site within a regulatory domain. We have already shown that the protein kinase C inhibitor H-7 (1-(5-isoquinolinylsulfonyl)-2-methylpiperazine) specifically blocked accumulation of viral unspliced gag-pol mRNA. Therefore, the phosphorylation at serine 70 may be involved in the regulation of Rex function in response to extracellular stimuli.

Amino Acid Sequence↗
PubMed1992

Expression of calpain II gene in human hematopoietic system cells infected with human T-cell leukemia virus type I.

We examined the distribution of calpains I and II in human hematopoietic system cell lines by Western and Northern blot analyses and enzyme activity assay. Expression of calpain I, a low Ca(2+)-requiring cysteine protease, was observed in all human T-cell lines tested. By contrast, expression of calpain II, a high Ca(2+)-requiring form, in human T-cells was closely correlated with human T-cell leukemia virus type I (HTLV-I) infection, which is known to result in the expression of adult T-cell leukemia-associated antigens, interleukin-2 (IL-2) receptor alpha, and Ca(2+)-dependent cell proliferation. Specific expression of calpain II in HTLV-I-infected cells occurred at the mRNA level. Furthermore, expression of calpain II in human natural killer-like cells was augmented by HTLV-I pX gene transfection. In HTLV-I-infected cells, the trans-acting transcriptional activation of the long terminal repeat and control elements for the IL-2 receptor alpha, c-fos, and granulocyte-macrophage colony-stimulating factor genes by the Tax from the pX gene is already known. Our results suggest that the similar trans-activation occurs to the calpain II gene in HTLV-I-infected hematopoietic system cells.

Blotting, Western↗
PubMed1992

Transforming activity and the level of Tax protein: effect of one point mutation in HTLV-I tax gene.

The transcriptional trans-activator molecule of HTLV-I, Tax, is known to transform rodent fibroblasts. A revertant clone expressing Tax was obtained by treating transformed Rat-I cells harboring a single copy of the tax gene with a mutagen. Sequence analysis of the tax gene of the revertant clone revealed that it had one point mutation at codon 12(CTT----TTT), resulting in a change from Leu to Phe. The colony-forming efficiencies of the cells transfected with the mutant tax gene (mu71 tax) were significantly lower than those transfected with the wild-type by the soft-agar method. This difference was shown to be due to the instability of mu71 Tax.

Amino Acid Sequence↗
PubMed1992

Intranuclear topological distribution of HIV-1 trans-activators.

Subcellular localization of human immunodeficiency virus type I (HIV-1) Tat and Rev was examined using a confocal laser scanning microscope (CLSM). In transfected COS-7 cells, Tat resided exclusively in the perinocleolar region, while Rev infiltrated fully into the nucleoli. The chimeric Tat in which the nucleolar targeting signal was replaced by that of Rev, which retains trans-acting activity of Tat, remained still in the perinucleolar region as wild-type Tat. Perinucleolar distribution of Tat protein suggests the existence of a novel nucleolar architecture that affects transcription.

Amino Acid Sequence↗
PubMed1992

Molecular diversity in amino-terminal domains of human calpastatin by exon skipping.

Calpastatin, a specific inhibitor of calpain, consists of a unique N-terminal domain (domain L) and four repetitive calpain-inhibition domains (domains 1-4). Calpastatin cDNA of human was reported to have two deletions in domains L and 1, as compared with that of pig and rabbit. We isolated human calpastatin genomic DNA clones, and the sequence analysis revealed seven exons for domain L and five exons for domain 1. Those deletions in the human cDNA were retained in its genomic DNA as exons 3 and 11. By the reverse transcription polymerase chain reaction method, three calpastatin cDNAs, full-length domains L and 1, and two natural mutants with deletions in either exon 3 or in both exons 3 and 5, were cloned from human fibroblast WI-38 cell line mRNA. Domain L was found to be rich in basic amino acid residues, especially for exon 3, and its N-terminal half was highly conserved among species. The isoelectric points (pI) of domain L and domains 1-4 were calculated to be 10.27 and 4.26-4.90, respectively. Moreover, human tissues and cell lines displayed different patterns of reverse transcription polymerase chain reaction products in agarose gel electrophoresis. Therefore, alternative splicing is most likely the cause for the molecular diversity, and the multiple isoforms are implicated for specific physiological roles.

Base Sequence↗
PubMed1992

[2D time of flight stereoscopic MR angiography of pulmonary vessels].

Two-dimensional (2D) time-of-flight (TOF) stereoscopic MR angiographies (MRA) of the pulmonary vessels were obtained from 15 healthy volunteers and five patients with pulmonary cancer in the mediastinum and pulmonary hilum. Fifteen healthy volunteers were examined using FLASH (Fast Low Angle Shot) with breath holding (40/8/40, TR/TE/flip angle). Except for the left superior pulmonary vein, pulmonary vessels in the mediastinum and hilum were well defined on stereoscopic MRA images. Although it was difficult to define the pulmonary arteries in the peripheral zone, intersegmental veins were easily defined with this method. In five cases of pulmonary cancer that were confirmed to show definite tumor involvement of the pulmonary vessels in the mediastinum and hilum by enhanced CT and MRI (SE method), irregular narrowing and interruption of the vessels were shown on MRA. In conclusion, 2D TOF stereoscopic MRA is considered a noninvasive, effective method for evaluation of the morphology of pulmonary vessels adjacent to the tumor in the mediastinum and hilum.

Adenocarcinoma↗
PubMed1992

[Evaluation of breath-hold multislice dynamic MRI of hepatocellular carcinomas].

The breath-hold multislice dynamic study (BMDS) in MRI, which can scan the entire liver during a single breath-holding, was applied to 16 patients with 30 focal lesions of hepatocellular carcinoma (HCC). The BMDS was performed at 20 seconds and 3 minutes after the bolus injection of Gd-DTPA, by gradient echo pulse sequence (FLASH). 29 nodules were detected in the BMDS, showing rapid enhancement on early phase and decline on delayed phase images. The BMDS was more sensitive than conventional MR images. Therefore, the BMDS seems to be useful for the diagnosis of HCC with multiple as well as solitary nodules.

Carcinoma, Hepatocellular↗
PubMed1992

[Detection of intrahepatic lipids by 1H-MRS--studies by breath-holding & 1 cm3 VOI].

The authors performed 1H-MR spectroscopy (MRS) to depict lipids in the liver of 10 healthy volunteers. Spectra were obtained by a 1.5 T-MR unit, with STEAM from 1 x 1 x 1 cm3 VOI. Lipid peaks were depicted in 7 of the 10 volunteers by breath-holding 1H-MRS study, while in only 4 on normal breathing. The existence of lipids could not be depicted through chemical shift imaging adopting in-phase & opposed images. This suggests a clinical utility of 1H-MRS, particularly through breath-holding studies, in depicting lipids from 1 x 1 x 1 cm3 VOI in the liver in vivo.

Humans↗
PubMed1992

Multiple forms of rat calpastatin cDNA in the coding region of functionally unknown amino-terminal domain.

Partial mouse and rat calpastatin cDNAs containing functionally unknown amino-terminal regions were cloned by the polymerase chain reaction (PCR) method. Two types of clones were obtained for the rat calpastatin; one had a sequence similar to mouse and human calpastatins, while the other had a deletion of 38 amino acid residues in this region. Both types of the rat sequence differed from the previously reported rat calpastatin which had additional deletions. The occurrence of multiple forms of calpastatin suggests alternative splicing in the functionally unknown domain.

Amino Acid Sequence↗
PubMed1992

The presence of antibodies to purified p24gag protein of HTLV-I in sera of patients with systemic lupus erythematosus (SLE).

Sera of patients with systemic lupus erythematosus (SLE) were tested for their reactivity to HTLV-I by western blotting (WB). Seven (18%) of 40 SLE serum samples reacted to the p24gag protein of HTLV-I by WB using purified gag antigens. The specificity of anti-p24gag antibodies in the SLE sera was confirmed by competitive inhibition on WB. Two of the seven patients were shown to be HTLV-I carriers, because HTLV-I infected T cell lines were easily established from their peripheral blood mononuclear cells (PBMC). Except for these two carrier patients, the gag proteins were not detected in the lysates of PBMC by WB using anti-p24gag and anti-p19gag monoclonal antibodies. The gag and pX genes of HTLV-I were not detected by PCR in PBMC of the SLE patients, with the exception of the 2 HTLV-I carrier patients. These results show no direct involvement of HTLV-I in the etiology of SLE. However, the existence of a specific antibody to p24gag in the sera of some of the noncarrier SLE patients suggests a crossreactivity to either unknown viruses or some autoantigens.

Base Sequence↗
PubMed1992

Induction of avascular yolk sac due to reduction of basic fibroblast growth factor by retinoic acid in mice.

Vasculogenesis depends on autocrine secretion of basic fibroblast growth factor (bFGF) from capillary endothelial cells. Retinoic acid (RA) induced avascular yolk sac (AVY) of mouse embryos of dams given 60 mg/kg of RA orally on Day 8 of gestation and sacrificed 3 days later. We studied the localization and transcriptional expression of bFGF and FGF-receptor (flg), heparin-binding growth factor (HBGF) activity, localization of lysosomal enzymes and alpha 1-antitrypsin (AAT), and electron microscopy of the normal mouse visceral yolk sac (VYS) and AVY. bFGF, which is normally present in the endoderm of the VYS of 8-day-old embryos and in all components of the VYS by Day 11 of gestation, was reduced in the AVY. However, in the presence of bFGF in vitro capillary nets were restored in the AVY. The mRNA for bFGF was not detectable in either VYS or AVY, while flg mRNA was detected equally in both organs in Northern blotting. The characteristic distribution pattern of lysosomal enzymes, acid phosphatase, lysozyme, and cathepsin D, and AAT was altered in the AVY. The level of acid phosphatase and AAT was reduced to 10% in the AVY. Electron microscopy revealed a partial or total loss of lysosomal membranes where the contents of lysosomes fused with adjacent lysosomes and the external organelles. These results suggest that vitelline blood vessels are not developed by endogenous autocrine bFGF but by exogenous transcellular bFGF from absorptive endodermal cells. Retinoic acid does not affect the angiogenic capacity of the VYS mesenchyme but destroys lysosomes, which release hydrolytic enzymes, leading to degradation of AAT in the endodermal cells and then digestion of endocytosed bFGF.

Acid Phosphatase↗
PubMed1992

Maturational stage specific immunoglobulin heavy chain gene rearrangements, determined by D and D upstream region gene structures.

In 43 cases of various B-cell lineage tumors, precise gene structures of rearranged immunoglobulin heavy chain (IgH) were studied. By Southern-blot analysis of D upstream (5'D) gene of IgH, biallelic rearrangement structures, D-J or V-D-J, were determined and consequently maturational stage specific IgH rearrangement patterns were investigated. B-precursor ALL cases (especially stage IV of Nadler's criteria) have V-D-J rearranged IgH genes on both alleles. In contrast, most of the mature B-cell malignancies, excluding multiple myeloma, have IgH genotype of D-J/V-D-J. In addition, in case of D-J/V-D-J, the D gene used in D-J joining has been speculated by Southern-blot of D genes. So, these approaches for inquiring precise structures of rearranged IgH genes are supposed to provide new information of lymphocyte differentiation and leukemogenesis.

Antigenic Variation↗
PubMed1992

Commitment reversion model of unrestricted cell growth.

Through the analysis of accumulated experimental data of cell growth, a model of unrestricted cell growth is presented here. This model is based hypothetically on the cellular commitment to senescence as in the previously presented commitment theory. Cells are divided into 3 types, namely uncommitted cells, committed cells and terminal cells. The division of an uncommitted cell produces an uncommitted cell itself and a committed cell of the first generation. This committed cell goes through a limited number of cell divisions until the cells become non-dividing terminal cells. It is hypothesized that during a committed cell division, there is a very small probability that an uncommitted cell may be generated. With computer simulations, it is estimated that a committed cell of the first generation may divide around 30 times until they become non-dividing terminal cells, and that the probability of an uncommitted cell regeneration for each committed cell division may be 2(-H). This hypothesis may possibly clarify some aspects of the biological phenomena of cell growth, which can not be explained by the previous commitment theory, such as the growth pattern of cultured diploid cells, cancer initiation and promotion, and cancer progression and metastasis.

Animals↗
PubMed1992

Inhibition of human immunodeficiency virus type 1 Rev function by a Rev mutant which interferes with nuclear/nucleolar localization of Rev.

A nonfunctional mutant of human immunodeficiency virus type 1 Rev was created by deleting seven amino acid residues within the nucleolar targeting signal. This mutant Rev remained in the cytoplasm in expressed cells and strongly inhibited the function of Rev by interfering with the nuclear/nucleolar localization of coexpressed Rev. These findings strongly suggest the multimerization of Rev in the cytoplasm before migration to the nucleus/nucleolus, where wild-type Rev functions as a trans-regulator.

Amino Acid Sequence↗
PubMed1992

Correlation of basic fibroblast growth factor expression levels with the degree of malignancy and vascularity in human gliomas.

Basic fibroblast growth factor (FGF) is a mitogen, a differentiation factor for neuroectoderm-derived cells, and a potent angiogenic factor. The authors have previously demonstrated that the messenger ribonucleic acid of basic FGF is expressed in more than 90% of human gliomas. In the present study, they examined the expression of basic FGF in human glioma tissues using immunohistochemical techniques with a mouse monoclonal antibody against human basic FGF. They also correlated the basic FGF level with the histological grades of malignancy assessed by the number of nucleolar organizer regions (NOR's). Basic FGF was detected in 18 of 19 gliomas, whereas it was undetectable in two normal brains. The expression level of basic FGF peptide increased proportionally with the degree of malignancy. There was also a tendency for the number of NOR's in glioma cells to increase in glioma samples with a high level of basic FGF expression. Furthermore, most of the cases with increased vascularity demonstrated on cerebral angiograms showed a relatively high level of basic FGF expression of tumor cells and a large number of NOR's in endothelial cells in tumor tissues. These results suggest that basic FGF is actually produced in most gliomas and is involved in tumorigenesis and malignant progression as an autocrine growth factor. Moreover, basic FGF may play an important role in tumor neovascularization as a paracrine angiogenic factor.

Animals↗