Search PubMed⌕ Search

Biomedical subjects

S Tajima

Publications and source records attributed to S Tajima.

At least 253 records · Page 14Linked to original sources
PubMed1995

Stimulated expression of decorin and the decorin gene in fibroblasts cultured from patients with localized scleroderma.

Decorin mRNA levels, the content of decorin and the synthesis of dermatan sulphate in skin fibroblasts from patients with systemic and localized scleroderma were investigated. Approximately a 2.2-fold increase in decorin mRNA levels, was found by Northern blot analysis in localized scleroderma, but no significant changes were found in systemic scleroderma. Decorin, as measured by an immunoblot assay, was increased 2.6-fold in fibroblast cultures from localized scleroderma but not in those from systemic scleroderma. In contrast, the synthesis of dermatan sulphate was similar in both conditions. These results indicate that altered decorin gene expression causes abnormal proteoglycan metabolism in localized scleroderma.

Adult↗
PubMed1995

Stimulation of elastin expression by minoxidil in chick skin fibroblasts.

Minoxidil inhibited the proliferation of embryonic skin fibroblasts during the growth phase but not during the stationary phase. Minoxidil stimulated elastin synthesis two-fold in a dose-dependent manner at a concentration of 1 mM during the stationary phase. The stimulation of elastin synthesis paralleled a comparable increase in elastin mRNA level. These results suggest that the stimulation of elastin expression by minoxidil in skin fibroblasts was controlled at the elastin mRNA level and also suggest that its elastin-stimulating effect is not related to the suppressive effect on cell proliferation. Minoxidil appears to be a potent stimulator for elastin expression in skin fibroblasts.

Animals↗
PubMed1995

Partial characterization of a unique 84-kDa polypeptide stimulated by ascorbic acid in skin fibroblasts.

Ascorbic acid stimulated the synthesis of a noncollagenous 84 kDa polypeptide by up to 3.5-fold in primary cultures of chick skin fibroblasts. Stimulation was observed with concentrations ranging 0.4 to 50 micrograms/ml and was dose-dependent within the concentrations up to 10 micrograms/ml during 24 h treatment under conditions in which procollagen synthesis was increased. This protein was found to be translated with a molecular size of 84 kDa in an in vitro cell-free translation experiment, indicating that the 84 kDa polypeptide was a primary translate. The stimulation was accompanied by a 1.7-fold increase in translational activity of the mRNA for this polypeptide. Its synthesis rapidly reduced when the cells were serially passaged until the third subcultivation, whereas procollagen synthesis remained essentially constant. These results indicate that the stimulation of this unique 84 kDa polypeptide by ascorbic acid was modulated at least in part at a translational level and its synthesis appears to be related to in vitro cellular aging.

Animals↗
PubMed1995

Response of 3-hydroxy-3-methylglutaryl CoA reductase to l-triiodothyronine in cultured fibroblasts from FH homozygotes.

The effect of l-triiodothyronine on 3-hydroxy-3-methylglutaryl CoA (HMG CoA) reductase activity was measured in cultured skin fibroblasts from patients with homozygous familial hypercholesterolemia (FH). The tested strains were obtained from 13 receptor-negative and 6 receptor-defective type homozygotes and 3 heterozygotes. Eleven out of 19 strains of cultured fibroblasts from FH homozygotes demonstrated high levels of the HMG CoA reductase activity when l-triiodothyronine was present in the culture medium. All the 11 strains that responded to l-triiodothyronine were the receptor-negative type in which the binding of LDL on the cell surface was completely lacking. Two receptor-negative type strains showed no response to the addition of l-triiodothyronine. In these strains, partially active receptors were synthesized and rapidly degraded. The effect of l-triiodothyronine on HMG CoA reductase was abolished by cycloheximide, and not by actinomycin D. Furthermore, the effect was abolished by the pre-loading of the cells with free cholesterol. The results indicate that the effect of l-triiodothyronine on HMG CoA reductase activity was a post-transcriptional event, required de novo protein synthesis, and was successful only when cholesterol was depleted from the cells. The difference in the responsiveness of HMG CoA reductase activity to l-triiodothyronine treatment can be utilized to judge the state of impairment of LDL-receptors in the FH homozygote from the viewpoint of ability to incorporate cholesterol into the cells.

Cells, Cultured↗
PubMed1995

Tranilast inhibits collagen synthesis in normal, scleroderma and keloid fibroblasts at a late passage culture but not at an early passage culture.

We have previously reported that tranilast, an anti-allergic agent, specifically suppresses collagen synthesis in normal skin fibroblasts and to a greater extent in keloid fibroblasts. We found in this study that the specific suppression of collagen synthesis by tranilast was limited to the fibroblasts with a high passage number (passage 8-10). In normal skin fibroblasts with a low passage number (passage 1-2), tranilast exerted no significant effect on collagen synthesis. This was also observed with scleroderma and keloid fibroblasts. This result suggests that inhibition of collagen by tranilast will be dependent on in vitro cellular aging and that serial cell passages result in the loss of the cell phenotype resistant to tranilast effect.

Cells, Cultured↗
PubMed1995

Modulation of collagen synthesis and cell proliferation by retinoids in human skin fibroblasts.

The effect of the retinoids, 13-cis-retinoic acid (-RA), etretinate and all-trans-RA on collagen synthesis and cell proliferation of human skin fibroblasts was studied. These compounds all inhibited collagen synthesis at concentrations between 10(-8) and 10(-5) M after 48 h treatments. The inhibitory effect of 13-cis-RA was the most pronounced. Both all-trans-RA and etretinate inhibited DNA synthesis, to 60% and 53% of control value, respectively, at 10(-5) M. In contrast, 13-cis-RA did not show any significant effect on DNA synthesis at the concentrations used. 13-cis-RA appears to be a unique drug showing a pronounced inhibitor effect on collagen synthesis without affecting DNA synthesis and may prove a useful tool for the treatment of fibrotic diseases.

Adult↗
PubMed1995

The beta subunit of the signal recognition particle receptor is a transmembrane GTPase that anchors the alpha subunit, a peripheral membrane GTPase, to the endoplasmic reticulum membrane.

The signal recognition particle receptor (SR) is required for the cotranslational targeting of both secretory and membrane proteins to the endoplasmic reticulum (ER) membrane. During targeting, the SR interacts with the signal recognition particle (SRP) which is bound to the signal sequence of the nascent protein chain. This interaction catalyzes the GTP-dependent transfer of the nascent chain from SRP to the protein translocation apparatus in the ER membrane. The SR is a heterodimeric protein comprised of a 69-kD subunit (SR alpha) and a 30-kD subunit (SR beta) which are associated with the ER membrane in an unknown manner. SR alpha and the 54-kD subunits of SRP (SRP54) each contain related GTPase domains which are required for SR and SRP function. Molecular cloning and sequencing of a cDNA encoding SR beta revealed that SR beta is a transmembrane protein and, like SR alpha and SRP54, is a member of the GTPase superfamily. Although SR beta defines its own GTPase subfamily, it is distantly related to ARF and Sar1. Using UV cross-linking, we confirm that SR beta binds GTP specifically. Proteolytic digestion experiments show that SR alpha is required for the interaction of SRP with SR. SR alpha appears to be peripherally associated with the ER membrane, and we suggest that SR beta, as an integral membrane protein, mediates the membrane association of SR alpha. The discovery of its guanine nucleotide-binding domain, however, makes it likely that its role is more complex than that of a passive anchor for SR alpha. These findings suggest that a cascade of three directly interacting GTPases functions during protein targeting to the ER membrane.

Amino Acid Sequence↗
PubMed1995

Post-translational regulation of type I collagen synthesis by heparin in vascular smooth muscle cells.

Heparin is a potent inhibitor of smooth muscle cell proliferation. It reduced the level of type I collagen by one-half in culture medium of smooth muscle cells, whereas it increased the type I collagen expression 4-fold in the cell layer compartment under the conditions where it inhibited cell proliferation. No significant change in the level of prolyl hydroxylation in the newly synthesized type I procollagen or steady-state levels of pro alpha 1 (I) and pro alpha 2 (I) collagen mRNAs was detected after heparin treatment. Short-pulse and pulse-chase experiments revealed that heparin inhibited the secretion of type I procollagen and stimulated the accumulation of type I collagen in the extracellular space. These results suggest that heparin could modulate type I collagen expression at a posttranslational level. The modulation appeared to be closely related with its inhibitory effect on cell proliferation via two different mechanisms: the inhibition of the secretion of type I procollagen and stabilization of type I collagen in the cell layer. Heparin thus appears to be a multifunctional modulator for cell proliferation and the expression of type I collagen in vascular smooth muscle cells.

Animals↗
PubMed1995

Modulations of elastin expression and cell proliferation by retinoids in cultured vascular smooth muscle cells.

Effects of retinoid derivatives (retinol, retinal, retinoic acid, and etretinate) on elastin expression and cell proliferation in chick embryonic vascular smooth muscle cells were compared. Retinoic acid and etretinate inhibited cell proliferation to a greater extent than retinol and retinal. Retinol showed no significant effect on cell proliferation or elastin synthesis. Retinoic acid exhibited the most pronounced stimulatory effect on elastin synthesis with a maximum stimulation of 2.8-fold at the concentration of 10(-6) M for 24-48 h treatment. A comparable increase in elastin mRNA level was observed in the case of retinoic acid treatment. When the cells were serially passaged to the third subcultivation, elastin synthesis declined with increasing number of cell passages. Retinoic acid reversed this decline of elastin synthesis. The results indicate that retinoic acid was potentially active and retinol was inactive for both inhibition of cell proliferation and stimulation of elastin synthesis. The inhibitory activities of the four compounds for cell proliferation appear to parallel the stimulatory activities for elastin synthesis. The stimulation of elastin expression by retinoids may thus be closely related to the inhibition of cell proliferation.

Animals↗
PubMed1995

Differential expression of alpha 1 and alpha 2 chains of type VI collagen in the upper, middle, and lower dermal fibroblasts in vitro.

Levels of type VI collagen mRNAs were determined in cultured skin fibroblasts derived from the upper, middle, and lower layers. The level of alpha 1 (VI) collagen mRNA was the highest in the fibroblasts from the upper layer. In contrast, alpha 2 (VI) collagen mRNA level in the fibroblasts from the lower layer predominated over those in the upper and middle layers. The level of alpha 3 (VI) collagen mRNA was the same in the three dermal layers. When the fibroblasts from the upper layer were passaged successively, the alpha 1 (VI) collagen mRNA level declined and alpha 2 (VI) collagen mRNA level increased to those of the lower dermal fibroblasts. These results indicate that alpha 1 (VI) and alpha 2 (VI) collagen expressions in skin fibroblast cultures are heterogeneous and that successive passages of the upper dermal fibroblasts may result in transition of the phenotype of alpha 1 (VI) and alpha 2 (VI) expression to that of lower dermal fibroblasts. The modulation of the expression of alpha 1 (VI) and alpha 2 (VI) chains presumably reflects the process of cellular aging in vitro and should be a useful biochemical marker in studies of cell aging.

Adult↗
PubMed1995

Isolation and expression of a chicken DNA methyltransferase cDNA.

A 0.5 kb fragment of chicken DNA methyltransferase cDNA was PCR-amplified using a set of degenerate primers. A clone harboring a 5 kb insert was isolated from a cDNA library by screening with the PCR-amplified cDNA fragment as a probe. The elucidated nucleotide sequence gave a 4,614 nucleotide open reading frame, and the predicted protein was highly homologous to the mouse and human DNA methyltransferases, especially in the amino acid sequence of the catalytic domain in the carboxyl-terminal region. The cysteine-rich region and Lys-Gly repeat first found in the mouse sequence were also conserved in chicken. However, about 250 amino acid residues in the amino-terminal portion of chicken DNA methyltransferase diverged from the amino-terminus of the mouse or human sequence. Northern blot analysis showed that the message of chicken DNA methyltransferase was expressed at high levels in the testis, in the lung and in Marek's virus-transformed chicken T-lymphoma cells. Expression of the chicken DNA methyltransferase in COS1 cells demonstrated that the enzyme is a so-called maintenance-type methylase. When poly(dG-dC)-poly(dG-dC) was used as the methyl acceptor, to provide a measure of de novo methylase activity, the Km value for S-adenosyl L-methionine was about 5 microM, which was 10 times higher than that when poly(dI-dC)-poly(dI-dC) was used. The affinity of DNA methyltransferase for S-adenosyl L-methionine in catalyzing de novo-type methylation activity was lower than that in catalyzing maintenance-type activity, though it was still high enough for the enzyme to work as a de novo-type methylase under physiological conditions.

Amino Acid Sequence↗
PubMed1995

A novel DNA binding protein that recognizes the methylated c-Myc binding motif.

We detected a novel nuclear protein, MMBP-3, that bound to the c-Myc binding motif (CACGTG) in which deoxycytidine in the CpG sequence was methylated. MMBP-3 was partially purified by chromatography on heparin-agarose and hydroxyapatite, followed by affinity adsorption to a matrix coupled to the methylated binding motif. Its binding to the methylated c-Myc binding motif was specific, although it also recognized the unmethylated motif weakly. MMBP-3 was further found to recognize only one of two differently hemimethylated forms of the double-stranded c-Myc binding motif. MMBP-3 activity was detected in proliferating C2C12 and C3H/10T1/2 cells, and down regulated when the growth of these cells was inhibited. We propose that MMBP-3 plays a role in regulating the c-Myc function by recognizing the methylation state of the c-Myc binding motif in a growth-dependent manner.

Animals↗
PubMed1995

Modulation of elastin expression by heparin is dependent on the growth condition of vascular smooth muscle cells: up-regulation of elastin expression by heparin in the proliferating cells is mediated by the inhibition of protein kinase C activity.

The effect of heparin on elastin expression in the proliferating and quiescent phases of growth of smooth muscle cells was studied. Heparin stimulated elastin synthesis and its mRNA level 2-3 fold in the proliferating cells while it inhibited the cell proliferation. The inhibition of cell proliferation and the stimulation of elastin expression by heparin in the proliferating cells were mimicked by a potent protein kinase C antagonist, H-7, but not by H-89, W-7, and HA1004, suggesting that the effect of heparin is mediated by the inhibition of protein kinase C. In contrast, heparin inhibited elastin synthesis and its mRNA level slightly but exhibited no effect on cell proliferation in the growth-arrested cells. This result indicates that heparin reciprocally affects elastin expression depending on the growth state of smooth muscle cells. Heparin thus exerts a complex influence on elastin expression in smooth muscle cells.

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗
PubMed1995

Regulation of BPAG2 (180 kDa) gene expression in spontaneously transformed murine keratinocytes: tissue distribution, modulation during cell adhesion, and up-regulation by ascorbic acid.

Messenger RNA for BPAG2, a hemidesmosomal type XVII collagen, was detected specifically in cultured keratinocytes, not in melanocytes or dermal fibroblasts, and was localized preferentially in the skin and cornea, not in aorta, lung, kidney, or liver. Modulation of BPAG2 mRNA expression during keratinocyte adhesion and growth in culture was studied. BPAG2 mRNA level in the spreading phase was greater than that in cell attaching and proliferating phases. Ascorbic acid stimulated the BPAG2 mRNA level to 2 times the control in a dose- and exposure time-dependent manner. These results suggest that BPAG2 is expressed at a maximum level in the cell spreading phase and is up-regulated by ascorbic acid.

Animals↗
PubMed1995

Treatment of cutaneous sarcoidosis with tranilast.

Tranilast is an anti-allergic drug clinically used for the treatment of atopy or urticaria. The drug has been shown to have an anti-fibrotic effect as well. We treated two cutaneous sarcoidosis patients with tranilast, resulting in remission within three months of administration. This drug should be an excellent tool for the treatment of other granulomatous diseases.

Adult↗
PubMed1995

A case of linear type of lichen sclerosus et atrophicus?

We report a case of the linear type of lichen sclerosus et atrophicus (LSA). The patient had linear atrophic lesions from the left upper back to the left hand. Histological findings obtained from the upper back were those of typical LSA. Histology of the forearm showed mild changes suggestive of LSA. There were no histological features suggesting any association with localized scleroderma in either specimen. The relation between LSA and localized scleroderma is unclear at present. This case suggests that there is a linear form in LSA as already recognized in localized scleroderma.

Adult↗
PubMed1995

Treatment of granuloma annulare with tranilast.

Three cases of granuloma annulare which did not exhibit a self-limited course were treated with tranilast at the dose of 300 mg/daily. The treatment resulted in the resolution of skin lesions within three months of administration. Although spontaneous resolution is often observed in granuloma annulare, tranilast may provide an alternative therapy for the treatment of cases resistant to spontaneous healing.

Adult↗