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Biomedical subjects

Y Eto

Publications and source records attributed to Y Eto.

At least 145 records · Page 8Linked to original sources
PubMed1994

Effect of activin on luteinizing hormone-human chorionic gonadotropin receptor messenger ribonucleic acid in granulosa cells.

Activin (the dimer of inhibin beta-subunit) is involved in the modulation of granulosa cell function. Recent reports have indicated that activin had an effect on LH/human CG (hCG) receptor induction and steroidogenesis in granulosa cells. To characterize the regulation inducing LH/hCG receptor by activin, we investigated messenger RNA (mRNA) levels, the expression of the LH/hCG receptor, and intracellular cAMP accumulation in cultured rat granulosa cells. Northern blot analysis showed an increase in the LH/hCG receptor mRNA level with FSH (30 ng/ml) and activin (100 ng/ml) cotreatment, whereas activin alone could not augment LH/hCG receptor mRNA at all. After the addition of actinomycin D to the culture medium, LH/hCG receptor mRNA was more stable in the presence of FSH plus activin than in the presence of FSH alone. Similarly, a receptor binding assay revealed that the cotreatment with FSH and activin induced more LH/hCG receptor than FSH alone 96 h after exposure to hormone, but that activin (100 ng/ml) alone could not induce the LH/hCG receptor. Since the primary, if not the sole, second messenger mediating the action of FSH in granulosa cells has been shown to be cAMP, intracellular cAMP accumulation was measured in granulosa cells in the presence of FSH (30 ng/ml) and/or activin (100 ng/ml). Although FSH-stimulated cAMP accumulation reached a peak 15 min after incubation, activin did not significantly alter cAMP accumulation in either control nor FSH-stimulated granulosa cells, indicating that the effects of activin on the LH/hCG receptor in granulosa cells are not mediated by the increase in cAMP. These results demonstrate that activin enhances the FSH-induced LH/hCG receptor mRNA, LH/hCG receptor mRNA stability, and LH/hCG binding sites not due to the stimulation of the adenylate cyclase system. Although the signal pathway from the activin receptor has not been elucidated upon yet, activin is capable of increasing LH/hCG receptor levels through the accumulation of LH/hCG receptor mRNA levels.

Activins↗
PubMed1994

[A possible same genetic defect in two Niemann-Pick disease model mice].

We found two Niemann-Pick disease model mouse species, NCTR-BALB/c mouse and SPM mouse. NCTR-BALB/c mouse is known as a model mouse of Niemann-Pick disease type C, because cholesterol esterification is deficient in fibroblasts. On the other hand, SPM mouse has been thought as a model of Niemann-Pick disease type A. However, we disclosed cholesterol esterification in fibroblasts from SPM mice is also deficient. It indicates that two model mice could be caused by a same genetic deficiency. To test if the genetic defect of those mice are located in the same gene, we made NCTR-BALB/c mouse heterozygotes mate with SPM mouse heterozygotes. The F1 mice are investigated by lipid analysis, lysosomal enzyme assay, cholesterol esterification ratio, and electron microscopic study. Eleven in 42 F1 mice (25%) got affected, and the clinically affected F1 mice had the biological and morphological abnormalities which are seen in SPM and NCTR-BALB/c mice. These data suggest that genetic defects in NCTR-BALB/c and SPM mice are located in the same gene.

Animals↗
PubMed1994

Three new mutations in patients with myophosphorylase deficiency (McArdle disease).

We report three new mutations in patients with myophosphorylase deficiency (McArdle disease). A splice-junction mutation (G-to-A transition at the 5' end of intron 14) and a missense mutation (CTG to CCG at codon 291, changing an encoded leucine to a proline) were identified in Caucasian patients who were heterozygous for a common mutation reported elsewhere (CGA [Arg] to TGA [stop]) at codon 49. The splice-junction mutation destroyed the consensus sequence at the 5' splice site, and a cryptic splice site 67 bp upstream was recognized instead. As a result, there was a 67-bp deletion in the 3'-terminal region of exon 14 in the transcript, resulting in a frameshift with premature translation termination. A deletion of a single codon, 708/709 (TTC, specifying phenylalanine) was identified in Japanese patients. Two affected siblings were homozygotes, and their parents were heterozygotes. A third, unrelated patient was heterozygous for the same mutation, while the myophosphorylase gene on the other allele was only faintly expressed.

Adolescent↗
PubMed1993

Activin enhances osteoclast-like cell formation in vitro.

The effect of activin (activin A/EDF) on osteoclast formation was investigated. In mouse bone marrow cell cultures, activin enhanced the formation of tartrate-resistant acid phosphatase (TRACP)-positive multinucleated cells (MNC) in a dose-dependent manner, either in the presence or absence of 1,25-(OH)2D3 or PTH. In organ cultures of neonatal mouse calvaria, activin also enhanced the generation of TRACP-positive giant cells in the endosteal periosteum and increased the TRACP staining of whole calvaria, but did not exhibit bone resorbing activity. These results indicate that activin stimulates the formation of osteoclasts, but not osteoclast activation. Activin is produced by bone marrow cells and might be involved in the local process of osteoclast differentiation.

Acid Phosphatase↗
PubMed1993

Characterization of in vivo phosphorylation of activin type II receptor.

An antiserum was generated against a C-terminal peptide of the mouse activin type II receptor (ActR-II), which specifically immunoprecipitates ActR-II protein transiently expressed in COS-1 cells. Autophosphorylation activity of the ActR-II was examined in [32P]orthophosphate labeled COS-1 cells. The immunoprecipitated ActR-II protein was found to be phosphorylated on serine residues in the absence of ligand stimulation, and the phosphorylation was slightly increased after stimulation with activin A.

Activin Receptors↗
PubMed1993

Molecular characteristics in Japanese patients with lipidosis: novel mutations in metachromatic leukodystrophy and Gaucher disease.

The characterization of mutations in Japanese patients with lipidosis, particularly in metachromatic leukodystrophy (MLD) and Gaucher disease has been studied in detail. Metachromatic leukodystrophy is characterized by an accumulation of sulfatide in nervous tissues and kidney due to a deficiency of arylsulfatase A (ASA). We analyzed the presence of three known mutant arylsulfatase A alleles in Japanese patients with MLD. Among 10 patients of Japanese patients with MLD, we found that allele 445A mutation has moderately high incidence and also homozygosity of this mutation results in the late infantile form. Allele 2381T was not found in Japanese patients. Furthermore, we found novel mutation which is G- to A mutation at the 1070 nucleotide of the ASA gene (designated 1070 A) in Japanese patients with juvenile onset. This mutation results in a amino acid substitution of Gly245 by Arg and found in heterozygote form. Our studies of molecular analysis in 10 Japanese patients with MLD indicate that Japanese MLD patients have unique characteristics of ASA mutations compared with those of Caucasian patients. On the other hand, Gaucher disease is the most prevalent sphingolipidosis, characterized by an accumulation of glucocerebroside in macrophage derived cells due to a deficiency of lysosomal hydrolase glucocerebrosidase. To study the molecular basis of Gaucher disease in Japanese patients, we analyzed the presence of the two known mutations (6433C and 3548A) in the glucocerebrosidase gene of 15 patients with Gaucher disease. We found that the 6433C and 3548A mutations occur in all subtypes of Japanese patients with Gaucher disease.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1993

Molecular screening of Japanese patients with Gaucher disease: phenotypic variability in the same genotypes.

Gaucher disease is the most prevalent sphingolipidosis, characterized by genetic deficiency of lysosomal hydrolase glucocerebrosidase, and is inherited in an autosomal recessive manner. To characterize the molecular basis of Gaucher disease in Japan, we analyzed for the presence of the two known mutations (1448C and 754A) in the glucocerebrosidase gene of 15 patients (14 families) with Gaucher disease by selective amplification and restriction endonuclease analysis. We found that the 1448C and 754A mutations occurred in all three clinical subtypes of Japanese Gaucher disease patients. The 1448C mutation was found on 12 (40%) out of 30 chromosomes (44% allele frequency in nonneuronopathic form, and 33% in neuronopathic forms), while homozygosity for this mutation was only found in two nonneuronopathic patients (age of 1 year 6 months and 7 years). We detected the 754A mutation on 6 (20%) out of 30 chromosomes. No patient was homozygous for 754A mutation. Furthermore, we identified four patients who were compound hetrozygote for 754A and 1448C. One of these was a type 3 Gaucher patient, but the other three patients were free from central nervous system manifestations at the time of observation. These results indicate that phenotypic presentation of Gaucher disease including the presence of nervous manifestation, progression, and severity of disease, may be affected by other genetic, environmental, or developmental factors, as well as the glucocerebrosidase genotype.

Adolescent↗
PubMed1993

A new bacterial cellulose substrate for mammalian cell culture. A new bacterial cellulose substrate.

A new substrate for mammalian cell culture was developed using a cellulose membrane produced by Acetobacter aceti. Modification of the ionic charge of the membrane and adsorption of collagen to it promoted cellular adhesion to the membrane surface. The growth of eight kinds of cells on the membrane, was comparable to that achieved in plastic Petri dishes. The membrane was tested for use in the production of recombinant Erythroid Differentiation Factor (EDF)/activin A using genetically engineered Chinese hamster ovary cells. Both the viability of the cells and production of EDF/activin A were maintained for about 1 month, while cultures on plastic dishes lasted only 12 days. It was considered that the mechanism of improved cell viability was related to the ultrastructure of the cellulose membrane.

Acetobacter↗
PubMed1993

Presence and possible function of activin-like substance in human follicular fluid.

We assessed the presence of an activin-like substance in human follicular fluid that was obtained from women undergoing in-vitro fertilization using a bioassay for activin A. Activin activity was not detected in crude follicular fluids; the bioactivity of standard activin A was inhibited by the addition of follicular fluid. After the follistatin (binding protein of activin A) was removed from follicular fluid using a purification procedure, activin activity was detected in the follicular fluids (mean concentration: 131 +/- 40 ng/ml). Activin activity was inhibited by the addition of follistatin to fluid. The concentration of activin activity was substantially higher (approximately 100-fold) than that reported in serum. The concentration negatively and significantly correlated with the number of developed follicles in the ovary (r = 0.501, P < 0.01). These results suggest that activin A and its binding protein are present in follicular fluid in large amounts and that they may have a role in local ovarian regulation.

Activins↗
PubMed1993

Cloning of a human acid sphingomyelinase cDNA with a new mutation that renders the enzyme inactive.

A cDNA encoding human acid sphingomyelinase was initially obtained by screening a placental cDNA library in lambda gt11 with a synthetic oligonucleotide probe and subsequently with partial cDNA. The full-length cDNA, hPSM55, comprised 2,376 nucleotides, with a 5' untranslated sequence of 122 nucleotides, an open reading frame of 1,884 nucleotides encoding a protein of 627 amino acids, and a 3' untranslated region of 370 bases. hPSM55 was almost identical to pASM-1FL reported by Schuchman et al. (J. Biol. Chem. 266, 8531-8539, 1991) except for a 6 base pair deletion in the signal peptide, which indicated the possible removal of valine and leucine residues between positions 36 and 37, and a 463T- to C-transition, which indicated a possible substitution of 155arginine for cystine. This cDNA was expressed in both COS-7 cells and Chinese hamster ovary cells. There was no increase in acid sphingomyelinase activity in either cell line following transfection. However, the correction of a single base change, 463C to T, in hPSM55 caused increased acid sphingomyelinase activity in transfectants. These results suggest that the mutation of nucleotide 463C to T plays an important role in the catalytic activity of acid sphingomyelinase.

Amino Acid Sequence↗
PubMed1993

Well-developed infant with hypoxic-ischemic encephalopathy associated with EEG burst suppression and subcortical leukohypodensity on CT scan.

In the prediction of neurological sequelae after hypoxic-ischemic encephalopathy (HIE) in the newborn, the electroencephalogram (EEG) burst suppression pattern (BS) and subcortical leukomalacia can mean grave neurodevelopmental problems will develop. This study presents an infant with HIE associated with BS and subcortical leukohypodensity (SLH) on computed tomography scan. At first her neurodevelopmental outcome was considered poor, but unexpectedly she showed good development in 32 months follow-up. The findings of BS and SLH do not always result in a poor neurodevelopmental outcome, if the subsequent clinical state and EEG return to normal at an early stage.

Brain Ischemia↗
PubMed1993

Activin A: an autocrine inhibitor of initiation of DNA synthesis in rat hepatocytes.

The present study was conducted to examine the effect of activin A on growth of rat hepatocytes. EGF induced a 10-fold increase in DNA synthesis as assessed by [3H]thymidine incorporation in cultured hepatocytes. When activin A was added together with EGF, DNA synthesis induced by EGF was markedly inhibited. Inhibition was detected at a concentration of 10(-10) M, and 5 x 10(-9) M activin A almost completely blocked EGF-mediated DNA synthesis. Similarly, activin A completely blocked DNA synthesis induced by hepatocyte growth factor/scatter factor. Activin A was capable of inhibiting EGF-mediated DNA synthesis, even when added 36 h after the addition of EGF. With the same time interval, TGF-beta also blocked EGF-induced DNA synthesis. Although both activin A and TGF-beta inhibited growth of hepatocytes in a similar manner, either activin A or TGF-beta did not compete with each other in their binding when assessed by competitive binding using an iodinated ligand. When hepatocytes were incubated with EGF, release of bioactivity of activin A into culture medium was detected after 48 h or later. Activity of activin A was released from parenchymal cells but not from nonparenchymal cells. mRNA for beta A subunit of activin was detected only slightly in unstimulated hepatocytes, but markedly increased at 48 h after the addition of EGF. To determine whether endogenously produced activin A affects DNA synthesis, we examined the effect of follistatin, an activin-binding protein that blocks the action of activin A. An addition of follistatin significantly enhanced EGF-induced DNA synthesis. Finally, in partial hepatectomized rat, expression of mRNA for beta A subunit in liver was markedly increased 24 h after the partial hepatectomy. These results indicate that activin A inhibits initiation of DNA synthesis in hepatocytes by acting on its own receptor and that activin A acts as an autocrine inhibitor of DNA synthesis in rat hepatocytes.

Activins↗
PubMed1993

Existence of activin-A in A- and D-cells of rat pancreatic islet.

Activin-A, a member of the transforming growth factor-beta supergene family, stimulates insulin secretion in rat pancreatic islets and causes glycogenolysis in isolated rat hepatocytes. These observations prompted us to determine whether activin-A existed in rat pancreas by using an immunocytochemical method. Cells in pancreatic islets were stained by antibody against activin-A, whereas no immunoreactivity was observed in exocrine pancreas. Cells localized in the mantle of the islets were densely stained by the antibody. Immunoelectron microscopic study showed that activin-A existed in secretory granules in both A- and D-cells. Furthermore, studies using a double labeling method revealed that activin-A coexisted with glucagon in secretory granules in A-cells and with somatostatin in D-cells. Antibody against inhibin-A weakly stained cells in both the core and mantle of the islets only when the rat was pretreated with colchicine. Subtypes of activin subunit in islets were identified to be beta A by a reverse transcription-polymerase chain reaction method. In addition, mRNA for inhibin alpha-subunit was expressed in islets. However, mRNA for these inhibin subunits was not detected in exocrine pancreas. To further examine the action of activin-A on insulin secretion, we examined the effect of activin-A in a flow-through perifusion system. Activin-A induced a biphasic insulin secretory response in the presence of 2.8 mM glucose, and a low concentration of activin-A, which does not stimulate insulin secretion by itself, markedly enhanced glucose-mediated insulin secretion at concentrations above 2.8 mM glucose. Inhibin-A did not affect insulin secretion. These results suggest the existence of activin-A in A- and D-cells of rat pancreatic islets and raise the possibility that activin-A acts as a physiological regulator of carbohydrate metabolism.

Activins↗
PubMed1993

Effect of an activin A on follicle-stimulating hormone (FSH) receptor messenger ribonucleic acid levels and FSH receptor expressions in cultured rat granulosa cells.

Activin, a dimer of beta-subunits of inhibin, has been found to induce FSH receptor on cultured rat granulosa cells. The effect of activin on FSH receptor messenger RNA (mRNA) levels has not been elucidated. To study the effect of activin on FSH receptor mRNA levels, we used a specific complementary RNA probe to evaluate changes in FSH receptor transcripts in cultured rat granulosa cells. Granulosa cells obtained from immature diethylstilbestrol-treated rats contained two predominant FSH receptor mRNA transcripts (5.5 and 2.4 kilobases). Compared to the control, the treatment of granulosa cells with activin (100 ng/ml) increased FSH receptor mRNA in a time-dependent manner with a maximum of about a 4-fold increase at 24 h. FSH receptor mRNA markedly decreased after 48 h and maintained a level comparable to that found in the control. The FSH receptor expression was also increased by activin. Scatchard analysis of the binding of rat FSH to granulosa cells showed that the increase in FSH binding after activin treatment was due to an increase in the receptor number and not the affinity of binding. Treatment of granulosa cells for 24 h with activin (20-300 ng/ml) increased FSH receptor mRNA in a dose-dependent manner to a maximum of about a 4-fold increase at a concentration of 100-300 ng/ml. We analyzed rat type II activin receptor mRNA transcripts in cultured rat granulosa cells with a specific complementary RNA probe to study the action of activin on granulosa cells. Granulosa cells contained two predominant rat type II activin receptor mRNA transcripts (6.0 and 3.0 kilobases). Furthermore, we measured intracellular cAMP production by activin to examine the mechanism by which activin acts on granulosa cells. In result, activin alone did not increase intracellular cAMP accumulation. In conclusion, this study demonstrates that the effect of activin A on the induction of FSH receptor expression is associated with a change in FSH receptor mRNA levels, suggesting that modulation of follicle development occurs.

Activins↗