PubMed Health⌕ Search

Biomedical subjects

R Horiuchi

Publications and source records attributed to R Horiuchi.

67 records · Page 4Linked to original sources
PubMed1982

Inhibition of the nuclear entry of 3,3',5'-triiodo-L-thyronine by monodansylcadaverine in GH3 cells.

We have recently reported that the entry of 3,3',5-triiodo-L-thyronine (T3) into mouse 3T3 fibroblasts occurs by receptor-mediated endocytosis (Cheng, S. Y., Maxfield, F. R., Robbins, J., Willingham, M. C., and Pastan, I. (1980) Proc. Natl. Acad. Sci. U. S. A. 77: 3425-3429). In this communication, we evaluated the functional significance of this mode of entry using GH3 cells, a growth hormone-producing cell line which has a high number of T3 nuclear receptors. T3-specific, saturable membrane uptake systems were demonstrated in GH3 cells. Monodansylcadaverine, an inhibitor of alpha 2-macroglobulin, epidermal growth factor, vesicular stomatitis virus, and T3 uptake in fibroblasts, blocked virtually all of the cellular uptake of T3, with a half-maximal concentration of 29 microM. Concomitant with the inhibition of the cellular uptake of T3, the accumulation of T3 into nuclei was reduced. The inhibitory effect of monodansylcadaverine on the reduction of T3 incorporation into nuclei was not due to the inhibition of binding to nuclear receptors, but probably was due to a decrease in the cytoplasmic availability of T3 as a result of inhibition of cellular entry. These results indicate that the uptake of T3 by receptor-mediated endocytosis is a physiologically significant process.

Animals↗
PubMed1982

Affinity labeling of the plasma membrane 3,3',5-triiodo-L-thyronine receptor in GH3 cells.

The binding of 3,3',5-triiodo-L-thyronine (T3) to GH3 rat pituitary tumor cells was studied at 15 degrees C and was shown to be saturable, reversible, and stereospecific. Least-squares analysis of the binding data showed two classes of binding sites with dissociation constants of 1.8 +/- 0.2 nM and 260 +/- 30 nM and binding capacities of (5.2 +/- 0.2) X 10(4) and (1.6 +/- 0.2) X 10(6) sites per cell, respectively. Affinity labeling of intact cells was carried out by incubation of cells with 0.3 nM N-bromoacetyl-[125I]T3 at 15 degrees C for 1 hr. Analysis of the cellular extracts by sodium dodecyl sulfate gel electrophoresis showed three labeled protein bands with apparent molecular masses of 55, 47, and 33 kilodaltons (kDal) in a ratio of 86:7:7. The labeling of only the 55-kDal protein band was selectively reduced to 50% by 20 microM unlabeled T3. Highly purified plasma membranes of GH3 cells were prepared and shown to be free of nuclei. Affinity labeling of the purified plasma membranes gave the same labeling pattern as with intact cells. Peptide mapping by Staphylococcus aureus V8 digestion of the 55-kDal protein from cells or plasma membranes gave the identical peptide fragments. Thus the 55-kDal protein labeled from intact cells is the same protein as that from purified plasma membranes. These results together with our earlier findings [Horiuchi, R., Cheng, S.-y., Willingham, M. & Pastan, I. (1982) J. Biol. Chem. 257, 3139-3144] suggest that the 55-kDal protein may be involved in mediating the uptake of T3 in GH3 cells.

Affinity Labels↗
PubMed1980

Systemic hyalinosis or juvenile hyaline fibromatosis. Ultrastructural and biochemical study of cultured skin fibroblasts.

Biochemical examinations of a hyalinized skin tumor of systemic hyalinosis (juvenile hyaline fibromatosis) revealed an increase in chrondroitin sulfate synthesis by skin fibroblasts with an enlarged, rough surfaced endoplasmic reticulum as well as an increase in chondroitin sulfate content. Thse results indicate that systemic hyalinosis is a connective tissue disorder characterized by abnormal GAG synthesis of fibroblasts.

Adult↗
PubMed1980

Effect of thyrotropin on cell orientation and follicle reconstruction in rotated suspension culture of hog thyroid cells.

Isolated porcine thyroid cells were cultured in suspension by rotation on a gyratory shaker. In the absence of TSH, the cells associated into small, globular, and hollow aggregates or pseudofollicles and had microvilli only at the outer surface of the pseudofollicles which faced the culture medium. These pseudofollicles were inactive in terms of thyroglobulin synthesis and iodination. In the presence of TSH, cell aggregates were enlarged to 1 mm in diameter. Inside the aggregates. Inside the aggregates, the cells were reorganized into numerous functional follicles in which microvilli were oriented towards the follicular lumen. In both the presence and absence of TSH, Golgi apparatuses were found in the cytoplasm near the cell periphery bearing microvilli. These findings indicate that the TSH effects on thyroid cell morphology are to arrange the polarity of follicular cells in a proper direction and to enlarge the aggregates they form.

Animals↗
PubMed1976

Mucopolysaccharidosis with special reference to Scheie syndrome.

Three patients with Scheie syndrome are reported on. They were suspected to be suffering from mucopolysaccharidosis because of clinical, histological and electron microscopic observations. The Scheie syndrome diagnosis was based on urinary GAG analysis. Chase experiments with cultured fibroblasts from one of the patients showed retarded degradation of 35SO4-labeled intracellular GAG. In addition, the pathogenesis of mucopolysaccharidoses in connection with cellular GAG metabolism is discussed.

Adult↗
PubMed1975

Initial change of glycosaminoglycans in systemic scleroderma.

7 clinically uninvolved as well as 8 involved (6 moderately, 2 markedly) back or forearm skin specimens from 12 patients with systemic scleroderma were subjected to quantitative evaluation and to qualitative analysis of glycosaminoglycans (GAG) by one-dimensional and two-dimensional cellulose acetate electrophoresis. Skin specimens from the back, clinically uninvolved but histologically demonstrating the initial change, revealed increased amounts of hyaluronidase, chondroitinase-resistant GAG of varying electrophoretic mobilities, and one of them was chemically confirmed to be heparan sulfate variant, whereas involved skin specimens showed hardly this increase.

Adult↗
PubMed1975

An approach to experimental scleroderma, using urinary glycosaminoglycans from patients with systemic scleroderma.

As a result of intraperitoneal injections in mice of crude glycosaminoglycans obtained from the urine of patients with systemic scleroderma, a fibrotic process similar to the intial changes of human scleroderma was frequently observed, especially in the skin and esophagus when the glycosaminoglycans contained a probable variant of heparan sulfate. Furthermore, the scleroderma-like change was also observed, to some extent, in the ultrastructure of collagen fibers and glycosaminoglycans of the skin.

Animals↗
PubMedDate not supplied

Effects of OK-432 (picibanil) on the estrogen receptors of MCF-7 cells and potentiation of antiproliferative effects of tamoxifen in combination with OK-432.

OK-432 (picibanil), a streptococcal preparation, has a strong biological response modifier (BRM) function and is expected to produce clinical improvement and prolongation of survival in treated cancer patients in Japan. We were interested in whether OK-432 augments estrogen receptor (ER) levels in breast cancer. To investigate the effect of the BRMs on cellular growth and the characteristics of ER and progesterone receptors (PgR) in the human breast cancer cell line MCF-7, we used OK-432, Krestin (PSK), a protein-bound polysaccharide extracted from Coriolus versicolor, and lentinan, a fungal branched (1...3)-beta-D-glycan. OK432 and PSK dose dependently inhibited DNA synthesis of MCF-7 cells, and the 50% inhibitory concentrations of OK-432 and PSK were 1.2 KE (klinische Einheit, clinical unit)/ml and 200 micrograms/ml, respectively. Lentinan showed no direct anticancer effect in vitro. We found that OK-432 induced a 2-fold increase in ER levels in MCF-7 cells at 0.005 KE/ml, but not in PgR. Lentinan and low-dose PSK did not change ER or PgR levels, but high-dose PSK decreased ER and PgR. We also studied the combined effect of OK-432 and antiestrogens, tamoxifen (TAM) and DP-TAT-59. The combined treatment with OK-432 and TAM showed an additive inhibitory effect on MCF-7 cells. These results suggest that OK-432 may augment the therapeutic effect of TAM in breast cancer.

Antineoplastic Agents↗