Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P06889 (Mol)
 630,302 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We have established a stably transformed human neuroblastoma cell line (MC65) that conditionally expresses a C-terminal derivative of the amyloid beta protein precursor (beta PP) termed S beta C (a fusion protein composed of the amino-17 and carboxyl-99 residues of beta PP). Conditional expression of S beta C (mediated by the withdrawal of tetracycline from the culture medium) induces pronounced nuclear DNA fragmentation and cytotoxicity in this cell line. These effects are enhanced by hyperoxygen and suppressed by hypooxygen and antioxidants. This cell line is relatively insensitive to the extracellular application of amyloid beta 25-35, and coculture experiments suggest that this cytotoxicity is mediated by an intracellular process. These findings suggest that the overexpression of the C-terminal domain of beta PP can disrupt normal cellular processes in these cells in such a way as to induce a directed (deoxyribonuclease-mediated) mechanism of cell death. This process appears to be modulated and/or mediated by a reactive oxygen specie(s) (ROS). Consistent with a role for ROS in the process of S beta C-mediated toxicity, we have found that the MC65 cell line is hypersensitive to oxidative stress and that it is this sensitivity that appears (at least in part) to underlie its susceptibility to S beta C.
Mol Chem Neuropathol
PMID:Neurodegenerative mechanisms in Alzheimer disease. A role for oxidative damage in amyloid beta protein precursor-mediated cell death. 897 93

We have compared the cell and tissue selective estrogenic and antiestrogenic activities of tamoxifen, raloxifene, ICI 164,384 and a permanently ionized derivative of tamoxifen--tamoxifen methiodide (TMI). This non-steroidal antiestrogen has limited ability to cross the blood brain barrier and is therefore less likely to cause the central nervous system disturbances caused by tamoxifen. We have used the stimulation of the specific activity of the "estrogen induced protein", creatine kinase BB, as a response marker in bone, cartilage, uterine and adipose cells and in rat skeletal tissues, uterus and mesometrial adipose tissue. In vitro, TMI, tamoxifen and raloxifene mimicked the agonistic action of 17beta-estradiol in ROS 17/2.8 rat osteogenic osteosarcoma, female calvaria, and SaOS2 human osteoblast cells. In Ishikawa endometrial cancer cells, tamoxifen showed reduced agonistic effects and raloxifene showed no stimulation. However, as antagonists, tamoxifen and raloxifene were equally effective in Ishikawa or SaOS2 cells. In immature rats, all four of the antiestrogens inhibited estrogen action in diaphysis, epiphysis, uterus and mesometrial adipose tissue; when administered alone, tamoxifen stimulated creatine kinase (CK) specific activity in all these tissues. Raloxifene and TMI, however, stimulated only the skeletal tissues and had no stimulatory effect in the uterus or mesometrial fat, and the pure antiestrogen ICI 164,384 showed no stimulatory effect in any of the tissues. The simultaneous injection of estrogen, plus an antiestrogen which acted as an agonist, resulted in lower CK activity than after injection of either agent alone. These differential effects, in vivo and in vitro, may point the way to a wider therapeutic choice of an appropriate antiestrogen which, although antagonizing E2 action in mammary cancer, can still protect against osteoporosis and cardiovascular disease and not stimulate the uterus with its attendant undesirable changes, or interfere with the beneficial action of E2 in the brain.
J Steroid Biochem Mol Biol 1996 Dec
PMID:Tissue selective action of tamoxifen methiodide, raloxifene and tamoxifen on creatine kinase B activity in vitro and in vivo. 901 Mar 44

1alpha,25(OH)2-16-ene-D3, a synthetic analog of the steroid hormone, 1alpha,25(OH)2D3, has great potential to become a drug in the treatment of leukemia and other proliferative disorders, because of its minimal in vivo calcemic activity associated with a potent inhibitory effect on cell growth. However, at present, the mechanisms through which 1alpha,25(OH)2-16-ene-D3 expresses its biological activities are still not completely understood. Our previous in vitro study in a perfused rat kidney indicated for the first time that 1alpha,25(OH)2-16-ene-D3 and 1alpha,25(OH)2D3 are metabolized differently. 1alpha,25(OH)2-24-oxo-16-ene-D3, an intermediary metabolite of 1alpha,25(OH)2-16-ene-D3 formed through the C-24 oxidation pathway, accumulated significantly in the perfusate when compared to 1alpha,25(OH)2-24-oxo-D3, the corresponding intermediary metabolite of 1alpha,25(OH)2D3. In a subsequent in vivo study, we also reported that 1alpha,25(OH)2-24-oxo-16-ene-D3 exerted immunosuppressive activity equal to its parent, without causing significant hypercalcemia. In order to establish further the critical role of 1alpha,25(OH)2-24-oxo-16-ene-D3, in generating some of the key biological activities ascribed to its parent, we performed the present in vitro study using a human myeloid leukemic cell line (RWLeu-4) as a model. Comparative target tissue metabolism studies indicated that 1alpha,25(OH)2-16-ene-D3 and 1alpha,25(OH)2D3 are metabolized differently in RWLeu-4 cells, and the differences were similar to the ones we previously observed in the rat kidney. The significant finding was the accumulation of 1alpha,25(OH)2-24-oxo-16-ene-D3 in RWLeu-4 cells because of its resistance to further metabolism. Biological activity studies indicated that both 1alpha,25(OH)2-16-ene-D3 and its 24-oxo metabolite produced growth inhibition and promoted differentiation of RWLeu-4 cells to the same extent, and these activities were several fold higher than those exerted by 1alpha,25(OH)2D3. In addition, the genomic action of each vitamin D compound was assessed in a rat osteosarcoma cell line (ROS 17/2.8) by measuring its ability to transactivate a gene construct containing the vitamin D response element of the osteocalcin gene linked to the growth hormone reporter gene. In these studies, both 1alpha,25(OH)2-16-ene-D3 and its 24-oxo metabolite exerted similar but potent transactivation activity which was several fold greater than that exerted by 1alpha,25(OH)2D3 itself. In summary, our results indicate that the production and slow clearance of the bioactive intermediary metabolite, 1alpha,25(OH)2-24-oxo-16-ene-D3, in RWLeu-4 cells contributes significantly to the final expression of the enhanced biological activities ascribed to its parent analog, 1alpha,25(OH)2-16-ene-D3.
J Steroid Biochem Mol Biol 1996 Dec
PMID:1alpha,25-dihydroxy-24-oxo-16-ene vitamin D3, a metabolite of a synthetic vitamin D3 analog, 1alpha,25-dihydroxy-16-ene vitamin D3, is equipotent to its parent in modulating growth and differentiation of human leukemic cells. 901 Mar 46

The sequences in the rat osteocalcin gene that lie 3' to the vitamin D response element (VDRE) have been shown to augment transcriptional activation by 1,25-dihydroxyvitamin D3 [1,25-(OH)2D3]. These DNA sequences, however, are unable to bind the VDR or mediate 1,25-(OH)2D3 responsiveness independently of the VDRE. To further characterize this region, the functional properties of a series of mutant oligonucleotides were examined in transiently transfected ROS 17/2.8 cells. When these mutant oligonucleotides were expressed upstream of the heterologous herpes simplex virus thymidine kinase promoter, the bases between -420 and -414 of the rat osteocalcin gene were identified as critical for maximal transactivation by 1,25-(OH)2D3. Furthermore, mutation of these sequences in the context of the native osteocalcin promoter and enhancer totally abolished the ability of the VDRE to mediate 1,25-(OH)2D3 responsiveness. These bases, which are essential for the 1,25-(OH)2D3 responsiveness of the rat osteocalcin gene, are also present in a similar position, relative to the VDRE, in the human osteocalcin gene. To explore whether these sequences could enhance transactivation by other inducible transcription factors, they were examined for their ability to synergize with the chick vitellogenin estrogen response element and the rat somatostatin cAMP response element. When placed upstream to the herpes simplex virus thymidine kinase promoter and transfected into ROS 17/2.8 cells, these sequences were able to enhance transcriptional responsiveness to 17beta-estradiol and forskolin, respectively, demonstrating that they also contribute to transactivation by other inducible transcription factors.
Mol Endocrinol 1997 Feb
PMID:DNA sequences downstream from the vitamin D response element of the rat osteocalcin gene are required for ligand-dependent transactivation. 901 68

Lipid peroxidation (LPO) in rat testis and heart microsomes was compared using the ADP/Fe2+ as initiator with and without ascorbate at different concentrations. The extent of LPO was estimated by the levels of TBARS and PUFA. Without ascorbate, LPO was higher in heart than in testis despite elevated levels of catalase in heart. With increased ascorbate concentrations, a biphasic effect of LPO was observed. For a concentration < or = 0.2 mM, ascorbate acted as pro-oxidant and increased TBARS correlated with decreased PUFA were observed both in testis and heart. Above 0.2 mM, ascorbate acts as antioxidant but differences in the rate of LPO were observed. In heart decreased TBARS correlated with increased PUFA whereas in testis TBARS only decreased, PUFA were not significantly modified. These results suggest different mechanisms in LPO initiation in the two organs. Increasing concentrations of H2O2 produced directly elevated TBARS levels in testis while a lag phase was observed in heart before the increase, suggesting that H2O2 was the essential ROS produced by ascorbate-ADP/Fe2+. The effects of scavengers such as catalase and ethanol showed an inhibitory effect on TBARS production only in testis, suggesting the role of H2O2/OH. as an initiator of LPO. In heart, catalase produced a slight increase in TBARS levels whereas no modification was observed with ethanol, suggesting a possible direct activation by ADP/Fe2+ through a metal-oxo intermediate.
Mol Cell Biochem 1997 Apr
PMID:In vitro influence of ascorbate on lipid peroxidation in rat testis and heart microsomes. 908 45

The effect of calmodulin on the integral cGMP-activated conductance of ROS plasma membrane has been investigated by using the "patch-clamp" techniques (inside-out configuration). Calmodulin increased the apparent Michaelis constant (Km) from 19 +/- 1.5 (in the absence of calmodulin) to 33.7 +/- 5.5 mM. However, it did not influence the Hill coefficient and the maximum conductance of cGMP-channels. Ca2+ ions were required for the calmodulin effect (EC(50)= 452 +/- 47 nM). The results of our experiments with the use of 8-Br-cGMP and IBMX suggest that the modulating action of calmodulin was not mediated by the ROS phosphodiesterase activation. The action of some calmodulin inhibitors has been tested. On the basis of our study calmodulin is suggested to be very significant for the recovery and light adaptation processes by changing the affinity of the cGMP-channel for agonist.
Biochem Mol Biol Int 1996 Apr
PMID:Modulation of the cGMP-activated conductance of the plasma membrane of photoreceptor cells by calmodulin. 913 56

We studied the expression of estrogen-related receptor ERR-1 during mouse embryonic development. ERR-1 mRNA is present in bones formed by both the endochondral and intramembranous routes, and the onset of its expression coincides with bone formation. By RT-PCR experiments, we found that ERR-1, but not the related receptor ERR-2, is expressed in osteoblastic osteosarcoma cell lines as well as in primary osteoblastic cell populations derived from normal human bone. By gel shift analysis we found that ERR-1 binds as a monomer specifically to the SFRE sequence (SF-1-responsive-element; TCAAGGTCA). Mutation analysis revealed that both the core AGGTCA motif and the TCA 5'-extension are required for efficient ERR-1 binding. In transient transfection assays, ERR-1 acts as a potent transactivator through the SFRE sequence. This effect is cell-specific since ERR-1 activates transcription in the rat osteosarcoma cell line ROS 17.2/8 as well as in HeLa, NB-E, and FREJ4 cells but not in COS1 and HepG2 cells. Notably, the osteopontin (a protein expressed by osteoblasts and released in the bone matrix) gene promoter is a target for ERR-1 transcriptional regulation. Our findings suggest a role for ERR-1 in bone development and metabolism.
Mol Endocrinol 1997 Jun
PMID:The ERR-1 orphan receptor is a transcriptional activator expressed during bone development. 917 50

Cultured human and rat endothelial cells were used to study cellular toxicity and Ca2+ signalling upon exposure to reactive oxygen species. Superoxide and hydrogen peroxide (O2.-/H2O2) were produced by the hypoxanthine/xanthine oxidase system (HX/XO) and caused intracellular Ca2+ concentration ([Ca2+]i) to rise steadily when activities above 2 mU/ml were used. These Ca2+ increases were also measured when the glucose/glucose oxidase (G/GO) system above 5 mU/ml was used to produce hydrogen peroxide (H2O2). Gross morphological changes appeared to parallel elevated [Ca2+]i levels preceding cell death. However, when HX/XO or G/GO were used at non toxic doses rapid and transient changes in [Ca2+]i were measured. These treatments did not alter subsequent receptor mediated Ca2+ signalling induced by ATP (10 microM) or histamine (100 microM). Superoxide dismutase (50 U/ml), which dismutates O2.- into H2O2 also had no influence, whereas catalase (50 U/ml), which removes H2O2, completely diminished transient [Ca2+]i responses. H2O2 added directly was able to induce similar Ca2+ transients when concentrations of at least 500 microM were used. Buffering trace amounts of iron (o-phenanthroline; 200 microM) in order to inhibit .OH radical formation was not effective to alter Ca2+ changes. Experiments performed in Ca(2+)-free buffer showed a similar rise in [Ca2+]i and readdition of Ca2+ to the extracellular medium indicated the activation of store operated Ca2+ entry. Blocking Ca(2+)-ATPases of the endoplasmatic reticulum with thapsigargin (1 microM) inhibited ROS induced transient increases and cells preincubated with pertussis toxin (200 nM) showed unchanged Ca2+ transients after exposure to both enzyme systems. Phospholipase C inhibitor U73122 (2 microM) effectively reduced hydrogen peroxide induced emptying of intracellular stores. Taken together, we demonstrate that enzymatically produced non-toxic H2O2 rather than O2.- or .OH causes calcium signalling from thapsigargin sensitive stores, and activates store operated Ca2+ entry at least partially by activating phospholipase C. These changes clearly differ from pathological 'oxidative stress' associated with a progressive increase in [Ca2+]i.
Mol Cell Biochem 1997 Jun
PMID:Transient Ca2+ changes in endothelial cells induced by low doses of reactive oxygen species: role of hydrogen peroxide. 920 90

Interstitial collagenases participate in the remodeling of skeletal matrix and are regulated by fibroblast growth factor (FGF). A 0.2-kb fragment of the proximal human interstitial collagenase [matrix metalloproteinase (MMP1)] promoter conveys 4- to 8-fold induction of a luciferase reporter in response to FGF2 in MC3T3-E1 osteoblasts. By 5'-deletion, this response maps to nucleotides -100 to -50 relative to the transcription initiation site. The 63- bp MMP1 promoter fragment -123 to -61 confers this FGF2 response on the rous sarcoma virus minimal promoter. Intact Ets and AP1 cognates in this element are both required for responsiveness. The AP1 site supports basal and FGF-inducible promoter activity. The intact Ets cognate represses basal transcriptional activity in both heterologous and native promoter contexts and is also required for FGF activation. FGF2 up-regulates a DNA-binding activity that recognizes the MMP1 AP1 cognate and contains immunoreactive Fra1 and c-Jun. Both constitutive and FGF-inducible DNA-binding activities are present in MC3T3-E1 cells that recognize the MMP1 Ets cognate; prototypic Ets transcriptional activators are not present in these complexes. Inhibitors of protein kinase C, phosphatidyl inositol 3-OH kinase, and calmodulin-dependent protein kinase do not attenuate MMP1 promoter activation. FGF2 activates ERK1/ERK2 signaling in osteoblasts; however, 25 microM MAPK-ERK kinase (MEK) inhibitor PD98059 (inhibits by > 85% the phosphorylation of ERK1/ERK2) has no effect on MMP1 promoter activation by FGF2. Ligand-activated and constitutively active FGF receptors initiate MMP1 induction. Dominant negative Ras abrogates MMP1 induction by constitutively active FGFR2-ROS, but dominant negative Rho and Rac do not inhibit induction. The mitogen-activated protein kinase (MAPK) phosphatase MKP2 [inactivates extracellular regulated kinase (ERK) = Jun N-terminal kinase (JNK) > p38 MAPK] completely abrogates MMP1 activation, whereas PAC1 (inactivates ERK = p38 > JNK) attenuates but does not completely prevent induction. Thus, a Ras- and MKP2-regulated MAPK pathway, independent of ERK1/ERK2 MAPK activity, mediates FGF2 transcriptional activation of MMP1 in MC3T3-E1 osteoblasts, converging upon the bipartite Ets-AP1 element. The DNA-protein interactions and signal cascades mediating FGF induction of the MMP1 promoter are distinct from two other recently described FGF response elements: the MMP1 promoter (-123 to -61) represents a third FGF-activated transcriptional unit.
Mol Endocrinol 1997 Jul
PMID:Fibroblast growth factor receptor signaling activates the human interstitial collagenase promoter via the bipartite Ets-AP1 element. 921 60

The hormone 1alpha,25-dihydroxyvitamin D3 [1alpha,25(OH)2D3] generates biological responses via both genomic and rapid, nongenomic mechanisms. The genomic responses utilize signal transduction pathways linked to a nuclear receptor (VDRnuc) for 1alpha,25(OH)2D3, while the rapid responses are believed to utilize other signal transduction pathways that may be linked to a putative membrane receptor for 1alpha,25(OH)2D3. The natural seco steroid is capable of facile rotation about its 6,7 single carbon bond, which permits generation of a continuum of potential ligand shapes extending from the 6-s-cis (steroid like) to the 6-s-trans (extended). To identify the shape of conformer(s) that can serve as agonists for the genomic and rapid biological responses, we measured multiple known agonist activities of two families of chemically synthesized analogs that were either locked in the 6-s-cis (6C) or 6-s-trans (6T) conformation. We found that 6T locked analogs were inactive or significantly less active than 1alpha,25(OH)2D3 in both rapid responses (transcaltachia in perfused chick intestine, 45Ca2+ influx in ROS 17/2.8 cells) and genomic (osteocalcin induction in MG-63 cells, differentiation of HL-60 cells, growth arrest of MCF-7 cells, promoter transfection in COS-7 cells) assays. In genomic assays, 6C locked analogs bound poorly to the VDRnuc and were significantly less effective than 1alpha,25(OH)2D3 in the same series of assays designed to measure genomic responses. In contrast, the 6C locked analogs were potent agonists of both rapid response pathways and had activities equivalent to the conformationally flexibile 1alpha,25(OH)2D3; this represents the first demonstration that 6-s-cis locked analogs can function as agonists for vitamin D responses.
Mol Endocrinol 1997 Sep
PMID:Comparison of 6-s-cis- and 6-s-trans-locked analogs of 1alpha,25-dihydroxyvitamin D3 indicates that the 6-s-cis conformation is preferred for rapid nongenomic biological responses and that neither 6-s-cis- nor 6-s-trans-locked analogs are preferred for genomic biological responses. 928 67


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