Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: DrugBank:APRD00369 (ROS)
 19,271 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

In vitro studies were carried out to determine if reactive oxygen species modified DNA molecules are the preferred antigen for anti-DNA antibodies found in SLE sera. Reactive oxygen species were generated by 254 nm irradiation of hydrogen peroxide. Single stranded breaks, decrease in Tm and modification of adenine (21.7%) and thymine (48%) were the major effects observed on native DNA fragments of 300 bp in length. The ROS-modified DNA showed increased binding with naturally occurring anti-DNA autoantibodies as compared to unmodified DNA fragments. These results were substantiated by competition ELISA. Measurement of binding with DNA fragments of varying size revealed considerably increased binding as the fragment size increased from 50 bp to 800 bp. The relative affinity of anti-DNA IgG for ROS-modified and native DNA fragments of 300 bp were in the order of 6.26 x 10(-8) M and 4.07 x 10(-8) M, respectively.
 ...
PMID:Reactive oxygen species modified DNA fragments of varying size are the preferred antigen for human anti-DNA autoantibodies. 128 55

A detailed understanding of the mechanism of action of estrogen on bones is still lacking. The present study was designed to examine possible modulation by 17 beta-estradiol (E2) on the effects of 1,25-dihydroxyvitamin D3 [1,25-(OH)2D3] and on vitamin D receptors (VDR) in the ROS 17/2.8 osteoblast-like cell line. Cells were grown in phenol-red free medium supplemented with charcoal-stripped fetal calf serum (FCS). Total cellular VDR were measured in cell homogenates after extraction with a KCl hypertonic buffer. VDR-binding capacity doubled in the presence of 10 nM E2 (16.2 +/- 2.3 vs. 7.0 +/- 1.3 fmol/mg protein, respectively; P less than 0.01), while the Kd for 1,25-(OH)2D3 did not change (approximately 0.1 nM). Tamoxifen alone had no effect on VDR, while it completely abolished the E2-induced increase in VDR, indicating that the effect was specific for E2 and estrogen receptor mediated. 1,25-(OH)2D3 inhibited cell proliferation, determined by [3H] thymidine incorporation to DNA, in a dose-dependent fashion between 0.01-100 nM. The inhibitory effect of 1,25-(OH)2D3 on cell proliferation was significantly augmented in the presence of E2 (10 nM). 1,25-(OH)2D3 increased osteocalcin secretion to the medium by the cells in a dose-dependent fashion between 0.01-100 nM. In the presence of E2 (10 nM), maximal osteocalcin secretion in response to 1,25-(OH)2D3 was 3.5-fold higher than that in response to 1,25-(OH)2D3 alone. These results indicate that E2 modulates 1,25-(OH)2D3 activity in osteoblast-like cells, and that this effect can be attributed to an increase in VDR.
 ...
PMID:Evidence that estrogens modulate activity and increase the number of 1,25-dihydroxyvitamin D receptors in osteoblast-like cells (ROS 17/2.8). 131 50

The observation that vitamin D-mediated enhancement of osteocalcin (OC) gene expression is dependent on and reciprocally related to the level of basal gene expression suggests that an interaction of the vitamin D responsive element (VDRE) with basal regulatory elements of the OC gene promoter contributes to both basal and vitamin D-enhanced transcription. Protein-DNA interactions at the VDRE of the rat OC gene (nucleotides -466 to -437) are reflected by direct sequence-specific and antibody-sensitive binding of the endogenous vitamin D receptor present in ROS 17/2.8 osteosarcoma nuclear protein extracts. In addition, a vitamin D-responsive increase in OC gene transcription is accompanied by enhanced non-vitamin D receptor-mediated protein-DNA interactions in the "TATA" box region (nucleotides -44 to +23), which also contains a potential glucocorticoid responsive element. Evidence for proximity of the VDRE with the basal regulatory elements is provided by two features of nuclear architecture. (i) Nuclear matrix attachment elements in the rat OC gene promoter that bind nuclear matrix proteins with sequence specificity may impose structural constraints on promoter conformation. (ii) Limited micrococcal nuclease digestion and Southern blot analysis indicate that three nucleosomes can be accommodated in the sequence spanning the OC gene VDRE, the OC/CCAAT box (nucleotides -99 to -76), and the TATA/glucocorticoid responsive element, and thereby the potential distance between the VDRE and the basal regulatory elements can be reduced. A model is presented for the contribution of both the VDRE and proximal promoter elements to the enhancement of OC gene transcription in response to vitamin D. The vitamin D receptor plus accessory proteins may function cooperatively with basal regulatory factors to modulate the extent to which the OC gene is transcribed.
 ...
PMID:Vitamin D-responsive protein-DNA interactions at multiple promoter regulatory elements that contribute to the level of rat osteocalcin gene expression. 132 35

1,25-dihydroxyvitamin D3 [1,25(OH)2D3], plays an important role in the regulation of mineral ion homeostasis. As well as being the major steroid hormone that regulates calcium metabolism, 1,25(OH)2D3 suppresses transcription of the gene encoding parathyroid hormone, a peptide that plays a dominant role in regulating extracellular calcium levels. To identify DNA sequences that may mediate this transcriptional repression, nuclear extracts containing the 1,25(OH)2D3 receptor were examined for binding to sequences in the 5'-flanking region of the human parathyroid hormone gene. A 25-base-pair (bp) oligonucleotide containing the sequences from -125 to -101 from the start of exon I binds nuclear proteins recognized by monoclonal antibodies against the 1,25(OH)2D3 receptor. The sequences in this region contain a single copy of a motif (AGGTTCA) homologous to the motifs repeated in the up-regulatory 1,25(OH)2D3-response elements. When placed upstream to a heterologous viral promoter, the sequences contained in this 25-bp oligonucleotide mediate transcriptional repression in response to 1,25(OH)2D3 in GH4C1 cells but not in ROS 17/2.8 cells. This down-regulatory element, therefore, differs from the up-regulatory 1,25(OH)2D3-response elements both in sequence composition and in the requirement for particular cellular factors other than the 1,25(OH)2D3 receptor for repressing transcription.
 ...
PMID:Sequences in the human parathyroid hormone gene that bind the 1,25-dihydroxyvitamin D3 receptor and mediate transcriptional repression in response to 1,25-dihydroxyvitamin D3. 132 45

The effects of the immunosuppressive drug cyclosporin A (CsA) were evaluated on ROS 17/2.8 cells in vitro. ROS cells were treated with CsA (0, 0.5, 1.0, 5.0 micrograms/ml) for 3 days with and without bovine parathyroid hormone (bPTH) (1-34) 10 nM. CsA at 0.5, 1.0, 5.0 micrograms/ml without PTH and at 5.0 micrograms/ml in the presence of PTH significantly inhibited proliferation, as determined by a tetrazolium colorimetric assay. In addition, ROS cell number was significantly reduced at 3 and 4 days with CsA (5.0 micrograms/ml) without affecting cell viability. Incorporation of [3H]-thymidine into DNA was significantly reduced by 3.0 and 5.0 micrograms/ml CsA after 12 and 24 hours exposure. Basal and 1,25-dihydroxyvitamin D3-stimulated alkaline phosphatase levels in confluent ROS cells were reduced (P less than 0.05) with CsA (1.0 and 3.0 microgramS/ml). Pretreatment of ROS 17/2.8 cells with CsA did not alter PTH-stimulated cAMP levels or [125I]-PTHrP binding to ROS cells. CsA treatment of ROS 17/2.8 cells induced a spindle-shaped appearance with loss of attachment in confluent cultures. When ROS cells were cultured in CsA-containing media, cellular attachment at 6 and 12 hours was reduced (P less than 0.05) compared with untreated ROS cells. These findings indicate that CsA was capable of inhibiting proliferation, cell number, mitogenesis, alkaline phosphatase levels, and cell attachment of ROS cells without affecting PTH binding or cAMP levels. This direct effect of CsA on osteoblasts may be important in changes of bone remodeling observed in CsA-treated humans and animals.
 ...
PMID:Effects of cyclosporin A on rat osteoblasts (ROS 17/2.8 cells) in vitro. 133 Feb 39

Using immunoprecipitation and tryptic peptide microsequencing we confirmed the identity of normal rat kidney (NRK) cell-secreted 69-kDa major phosphoprotein as osteopontin (OP). We then immunoselected a 1.4-kilobase pair (kb) OP cDNA from a lambda gt11 library prepared from Kirsten sarcoma virus-transformed NRK (KNRK) cellular mRNA, using rabbit anti-69-kDa OP serum. Sequence analysis of this cDNA revealed the presence of a 52-nucleotide-long insert in the 5'-noncoding region, which was absent in OP cDNA cloned from the cDNA library of ROS 17/2.8 rat osteosarcoma cells. The insert sequence is flanked by putative intron splice junctions and is located 15-nucleotide upstream of the translational initiation site. An insert-specific 30-mer oligonucleotide probe hybridized to a single 1.5-kb RNA species from both NRK and KNRK cells, but not from ROS 17/2.8 cells. However, Southern analysis showed the presence of this insert sequence in the genomic DNA of both NRK and ROS 17/2.8 cells. Furthermore, PCR amplification of the insert-containing region using genomic DNAs from both NRK and ROS 17/2.8 cells gave products of identical size and sequence. Since OP is a single copy gene, these data provide strong evidence for differential cell type-specific processing of OP transcripts. In addition, we demonstrate that, in contrast to most transformed cells, levels of OP expression are significantly reduced in KNRK cells as compared to NRK cells.
 ...
PMID:Differential processing of osteopontin transcripts in rat kidney- and osteoblast-derived cell lines. 142 23

Osteoblasts play a pivotal role during the bioresponse of bone to agents that stimulate bone resorption and/or inhibit bone formation including hormones, polypeptide growth factors, and cytokines. We examined the cytokines interleukin-1-beta (IL-1 beta) and tumor necrosis factor-alpha (TNF-alpha) for their effects on osteoblastic proliferation and development and expression of alkaline phosphate and the osteoblast-specific protein osteocalcin in a mineralizing environment. Primary rat osteoblast-like cells (ROB) and osteoblastic cell lines derived from rat (ROS 17/2.8) and human (MG-63) osteosarcomas were studied. IL-1 beta and TNF-alpha were chosen because of their critical importance during the host response to local inflammatory stimuli. Qualitatively similar two- to threefold inhibition of osteocalcin synthesis by IL-1 beta and TNF-alpha were observed in all three postconfluent bone-forming model systems. Because of the readily measurable concentrations of osteocalcin produced in our culture protocol, it was not necessary to enhance osteoblastic synthesis of osteocalcin by supplementation with 1,25(OH)2-vitamin D3, a treatment which exerts pleiotropic effects on osteoblasts. Under the constraints of our protocol, where alkaline phosphatase and mineralization were already elevated at the 14-day onset of treatment, neither of these phenotypic properties was sensitive to a three-day cytokine exposure. Differences were noted in proliferation, where only TNF-alpha stimulated DNA synthesis in ROB cells, while both cytokines stimulated MG-63 cells. IL-1 beta and TNF-alpha failed to alter ROS 17/2.8 DNA synthesis except at the highest doses (25 pM IL-1 beta and 1 nM TNF-alpha) where inhibition was observed. These results further support the view that cytokine-mediated osteoblastic regulation can be relatively selective.
 ...
PMID:Effects of interleukin-1 beta and tumor necrosis factor-alpha on osteoblastic expression of osteocalcin and mineralized extracellular matrix in vitro. 145 94

The gene for rat bone gla protein (BGP) was isolated and 1250 basepairs (bp), including 1100 bp of 5' flanking DNA, were placed up-stream of the human GH reporter gene. After transient transfection into the osteoblast-like rat osteosarcoma cell line ROS 17/2.8, the BGP promoter demonstrated a low level of basal activity that was increased approximately 10-fold by the addition of 10(-8) M 1,25-dihydroxyvitamin D3 [1,25-(OH)2D3]. A single 250-bp fragment (-523 to -274) was sufficient to confer hormone inducibility upon both heterologous and homologous promoters. Deletion studies, complemented by evaluation with synthetic oligomers, enabled localization of the 1,25-(OH)2D3 response element to within 19 bp (-456 to -438), containing an element with an imperfect direct repeat [GGTGA(N4)GGACA] and homology to other steroid-responsive elements. Gel retardation assays demonstrated that partially purified chick intestinal 1,25-(OH)2D3 receptor bound specifically and with high affinity to a DNA fragment containing the putative 1,25-(OH)2D3 response element, and this binding was perturbed by monoclonal antibodies to the 1,25-(OH)2D3 receptor. Surprisingly, the 250-bp fragment, when linked in an antisense orientation with respect to the BGP promoter, blocked basal and hormone-dependent gene expression. However, a 246-bp fragment 5' to the 250-bp element (-1100 to -855) restored 20-fold inducibility when linked to the first fragment in the same orientation, suggesting cooperativity between at least two elements to achieve the hormonal regulation observed in this gene.
 ...
PMID:The vitamin D-responsive element in the rat bone Gla protein gene is an imperfect direct repeat that cooperates with other cis-elements in 1,25-dihydroxyvitamin D3- mediated transcriptional activation. 165 93

The interaction of the vitamin D receptor with a vitamin D-responsive element (VDRE) derived from the human osteocalcin promoter in vitro has been shown to require a nuclear accessory factor (NAF) derived from monkey kidney cells. In this report we show that this factor is widely distributed in cells and tissues, including those that do not express the vitamin D receptor (VDR). NAF is required for VDR binding to a variety of known VDREs. VDR and NAF independently bind the VDRE weakly, as assessed by elution profiles generated during VDRE affinity chromatography. Together, however, both proteins coelute from this column with a profile that indicates a tighter strength of interaction. Analogous chromatography of the VDR derived from ROS 17/2.8 cells treated with 1,25-dihydroxyvitamin D3 in culture also reveals a dual profile of weak and strong binding, suggesting that in vivo modifications are unlikely to alter receptor DNA binding. NAF is a protein of 55 kDa, as assessed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and cross-linking experiments suggest that the VDR and NAF together form a heterodimer on a single VDRE with a mol wt of 103 kDa. These data demonstrate that NAF is required for VDR binding to specific DNA in vitro and suggest the possibility that NAF may be required for the transactivation capability of the VDR in vivo.
 ...
PMID:A 55-kilodalton accessory factor facilitates vitamin D receptor DNA binding. 166 43

Type I collagen is expressed in a variety of connective tissue cells and its transcriptional regulation is highly complex because of the influence of numerous developmental, environmental, and hormonal factors. To investigate the molecular basis for one aspect of this complex regulation, the expression of alpha 1(I) collagen (COL1A1) gene in osseous tissues, we fused a 3.6-kb DNA fragment between bases -3,521 and +115 of the rat COL1A1 promoter, and three deletion mutants, to the chloramphenicol acetyltransferase (CAT) marker gene. The expression of these ColCAT transgenes was measured in stably transfected osteoblastic cell lines ROS 17/2.8, Py-la, and MC3T3-E1 and three fibroblastic lines NIH-3T3, Rat-1, and EL2. Deletion of the distal 1.2-kb fragment of the full-length ColCAT 3.6 construct reduced the promoter activity 7- to 30-fold in the osteoblastic cell lines, twofold in EL2 and had no effect in NIH-3T3 and Rat-1 cells. To begin to assess the function of COL1A1 upstream regulatory elements in intact animals, we established transgenic mouse lines and examined the activity of the ColCAT3.6 construct in various tissues of newborn animals. The expression of this construct followed the expected distribution between the high and low collagen-producing tissues: high levels of CAT activity in calvarial bone, tooth, and tendon, a low level in skin, and no detectable activity in liver and brain. Furthermore, CAT activity in calvarial bone was three- to fourfold higher than that in the adjacent periosteal layer. Immunostaining for CAT protein in calvaria and developing tooth germ of ColCAT3.6 mice also confirmed the preferred expression of the transgene in differentiated osteoblasts and odontoblasts compared to fibroblast-like cells of periosteum and dental papilla. This study suggests that the 3.6-kb DNA fragment confers the strong expression of COL1A1 gene in high collagen producing tissues of intact animals and that the 5' flanking promoter sequence between -3,521 and -2,295 bp contains one or more stimulatory elements which are preferentially active in osteoblastic cells.
 ...
PMID:Differential utilization of regulatory domains within the alpha 1(I) collagen promoter in osseous and fibroblastic cells. 173 Jul 46


1 2 3 4 5 6 7 8 9 10 Next >>