Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:3.6.1.3 (ATPase)
65,361 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A homogeneous population of trypsin-resistant epidermal cells has been isolated from newborn ICR mice. These cells are characterized by adherence, receptors for Fc-IgG, ATPase activity, phagocytosis of latex particles and opsonized sheep erythrocytes, and secretion of lysozyme and interferon. The production of interferon by these cells suggests that they may be important in protection against viral infections of the skin as well as in regulation of immune responses. The ultrastructure of these trypsin-resistant epidermal cells shows striking similarity to that of reticuloendothelial cells.
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PMID:Isolation and characterization of interferon-producing reticuloendothelial cells from mouse epidermis. 620 12

A cDNA clone complementary to an interferon (IFN)-induced mRNA approximately 3 kb in length was identified and sequenced revealing homology with the endoplasmic reticular heat shock protein/ATPase gp96. Both IFN-alpha and -gamma transcriptionally upregulate expression of this gene. gp96 transcripts, protein, and ATPase activity are shown to be enhanced as a result of IFN treatment in two human cell lines and this effect requires de novo protein synthesis. gp96 molecules have recently been implicated in the presentation of endogenous antigens. A number of the key elements in this pathway, the transporter proteins, the major histocompatibility complex (MHC)-linked units of the proteasomes and the MHC class I molecules are known to be IFN inducible. Our results show that yet another molecule suggested to play an accessory role in the endogenous presentation pathway is IFN inducible. Further, our studies represent the first demonstration of modulation of expression of a heat shock protein by a cytokine and identify a new enzymatic activity upregulated in IFN-treated cells.
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PMID:The endoplasmic reticular heat shock protein gp96 is transcriptionally upregulated in interferon-treated cells. 752 74

The normal human fibroblast line, TIG-3 which senesces at around 80 population doubling levels (PDLs), expressed interferon (IFN)-inducible genes such as 6-16, 2', 5'-oligoadenylate synthetase (2,5-A) and HLA B7 near the end of the proliferative lifespan. Other normal fibroblast line such as MRC-5 also expressed IFN-inducible genes when senesced. Clones transformed with SV40 T-antigen, which extended their proliferative lifespan by about 20-30 PDLs, also expressed IFN-inducible genes during their extended life. Anti-IFN-beta antibodies added in culture medium repressed the expression of IFN-inducible gene in both normal senescent and life-extended SV40-transformed cells. IFN-beta repressed DNA synthesis in normal TIG-3 and induced IFN-inducible genes in both normal and SV40-transformed TIG-3. Conditioned medium recovered from life-extended SV40-transformed cells contained IFN-beta, but not IFN-alpha, IFN-gamma or TNF-alpha and possessed an activity that inhibited DNA synthesis of young TIG-3. Addition of anti-IFN-beta antibodies into the medium enhanced the serum-induced DNA synthesis of near senescent (91% lifespan completed) TIG-3, while it neither induced DNA synthesis in fully senescent TIG-3 nor extended the proliferative lifespan of TIG-3. These results suggest that normal and SV40-transformed human fibroblasts increase expression of IFN-beta with increasing proliferative age especially near the end of their lifespan resulting in induction of IFN-inducible genes and possibly in growth repression.
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PMID:Increase in expression levels of interferon-inducible genes in senescent human diploid fibroblasts and in SV40-transformed human fibroblasts with extended lifespan. 756 72

Interferons are recognized to inhibit collagen production. Since fibrosis has been associated with liver dysfunction, we investigated the effects of alpha-interferon on the function and lipid composition of hepatocyte and erythrocyte plasma membranes derived from CCl4-cirrhotic male Wistar rats. In both cell types, CCl4 decreased Na+/K+ and Ca(2+)-ATPase activity and increased the cholesterol to phospholipids (CH/PL) ratio (p < 0.05). Administration of interferon (80,000 IU/kg s.c. for 8 weeks) increased survival from 40 to 90%, and preserved normal ATPase activity and CH/PL ratio. Our results show that administration of alpha-interferon to CCl4-cirrhotic rats improves survival, and liver and erythrocyte membrane function and composition, probably as a result of its antifibrogenic effect.
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PMID:Effect of alpha-interferon on erythrocyte and hepatocyte plasma membranes derived from cirrhotic rats. 830 89

The proteasomal system consists of a proteolytic core, the 20S proteasome, which associates in ATP-dependent and independent reactions with endogenous regulators providing specific substrate binding sites, chaperone function and regulation of activity to the protease. The best known regulators of the 20S proteasome are the 11S and the 19S complexes. Three subunits of the 20S proteasome and the two subunits of the 11S regulator are induced by gamma-Interferon. However, there are no indications for an influence of gamma-interferon on the subunit composition of the 19S regulator and only a few data exist about the dynamics of this complex. The analysis of 19S regulator subunits from yeast mutants reveals that the ATPases appear to be stringently organized in the 26S complex, while peripheral non-ATPases, such as S5a, might serve as subunits which shuttle substrates to the enzyme. A novel non-ATPase has been cloned, sequenced and identified in a complex besides the 19S regulator, the function of which is presently unknown. The dynamic structure of the 26S proteasome is also characterized by transient associations with components such as the modulator and isopeptidases. Certain viral proteins can also be associated with components of the proteasomal system and alter enzymatic activities.
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PMID:The 26S proteasome: a dynamic structure. 922 86

Rats were subjected to transient cerebral ischemia by four-vessel occlusion of 30 min duration, followed by 2, 4, 8 or 24 h of recovery. Total RNA was isolated from the cerebral cortex and hippocampus, and reverse transcribed into cDNA. Hsp40 mRNA levels of samples were evaluated by quantitative PCR. Transient cerebral ischemia caused a marked increase in hsp40 mRNA levels to about 250% and 500% of control in the cortex and hippocampus respectively. Since hsp40 exerts a critical regulatory function in the HSC70/HSP70 ATPase cycle, an ischemia-induced rise of hsp40 mRNA levels could mark the onset of the recovery process after transient ischemia. On the other hand, the inhibitory action of hsp40 on P58 (a protein that activates protein synthesis by blocking the interferon-induced double-stranded RNA-activated protein kinase PKR) implies that the rise in hsp40 expression may equally well contribute to the post-ischemic suppression of protein synthesis.
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PMID:Effects of transient cerebral ischemia on hsp40 mRNA levels in rat brain. 958 51

Two activators, named PA700 and PA28, are known to bind to 20 S proteasomes, forming two different complexes. The PA700-proteasome complex, also known as the 26 S proteasome, can degrade intact proteins, whereas complexes with PA28 can degrade only peptides. Monoclonal antibodies to 20 S proteasomes or the p45 ATPase subunit (Trip1, Sug1) of PA700 precipitated the same set of proteins from HeLa extracts, including six different ATPase subunits of PA700. This shows that p45 is not present in other protein complexes and suggests that all 26 S proteasome particles contain the same set of ATPase subunits. Interferons alpha and gamma had no effect on the composition of the 26 S proteasome, except for the replacement of subunits delta, MB1 and Z with Lmp2, Lmp7 and MECL1 respectively. Surprisingly, antibodies to PA28 precipitated p42, a component of PA700. Conversely, anti-p45 antibodies precipitated not only 26 S proteasomes but also PA28 alpha, beta and gamma, indicating that 20 S proteasomes can simultaneously bind both PA700 and PA28. PA28 alpha beta is known to be involved in antigen presentation. Conceivably, intact substrate proteins are recognized by PA700 and fed into proteasomes whose cleavage specificity is optimized for antigen presentation on MHC class I by PA28 and three interferon inducible proteasome subunits.
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PMID:Simultaneous binding of PA28 and PA700 activators to 20 S proteasomes. 962 Aug 78

1. Polyriboinosinic-polyribocytidylic acid (Poly I:Poly C), an interferon inducer was studied for its effect on gastric ulceration in rats. Polyriboinosinic-polyribocytidylic acid (1, 2 and 4 mg/kg, i.m.) showed a dose-dependent inhibition of gastric ulcers induced by aspirin, cold restraint stress and pylorus ligation (Shay's model). Protective dose (PD50) +/- SEM values of Poly I:Poly C on these models of ulcers were 1.9 +/- 0.2, 2.3 +/- 0.4 and 2.8 +/- 0.4 (mg/kg, i.m.) respectively. 2. Polyriboinosinic-polyribocytidylic acid (10-60 micrograms) produced dose-dependent inhibition of gastric proton pump (H+/K(+)-ATPase) activity in the gastric parietal microsomal fraction. The concentration of Poly I:Poly C causing a 50% inhibition (IC50) +/- SEM was found to be 17.6 +/- 1.2 micrograms. 3. Polyriboinosinic-polyribocytidylic acid caused a significant decrease in free and total acid and pepsin and an increase in mucin content in Shay (pylorus-ligated) rat. 4. Polyriboinosinic-polyribocytidylic acid did not exert a significant influence on isolated tissue preparations for anti-cholinergic (acetylcholine-induced contraction of guinea-pig ileum) and H2-anti-histaminic (histamine-induced contraction of rat uterus and guinea-pig auricle) activities. 5. Thus, the present study indicates that Poly I:Poly C may possess anti-gastric ulcer activity as a result of inhibition of the gastric proton pump.
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PMID:Interferon-inducer polyriboinosinic-polyribocytidylic acid: a potent anti-gastric ulcer agent and inhibitor of the gastric proton pump in rats. 967 29

P58(IPK), a member of the tetratricopeptide repeat and J-domain protein families, was first recognized for its ability to inhibit the double-stranded RNA-activated protein kinase, PKR. PKR is part of the interferon-induced host defense against viral infection, and down-regulates translation initiation via phosphorylation of eukaryotic initiation factor 2 on the alpha-subunit. P58(IPK) is activated in response to infection by influenza virus, and inhibits PKR through direct protein-protein interaction. Previously, we demonstrated that the molecular chaperone heat shock protein 40 (hsp40) was a negative regulator of P58(IPK). We could now report that influenza virus activates the P58(IPK) pathway by promoting the dissociation of hsp40 from P58(IPK) during infection. We also found that the P58(IPK)-hsp40 association was disrupted during recovery from heat shock, which suggested a regulatory role for P58(IPK) in the absence of virus infection. The PKR pathway is even more complex as we show in this report that the molecular chaperone, hsp/Hsc70, was a component of a trimeric complex with hsp40 and P58(IPK). Moreover, like other J-domain proteins, P58(IPK) stimulated the ATPase activity of Hsc70. Taken together, our data suggest that P58(IPK) is a co-chaperone, possibly directing hsp/Hsc70 to refold, and thus inhibit kinase function.
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PMID:The cellular inhibitor of the PKR protein kinase, P58(IPK), is an influenza virus-activated co-chaperone that modulates heat shock protein 70 activity. 992 Sep 33

The present studies evaluated the feasibility of establishing a conditionally immortalized osteoprecursor cell line derived from human fetal bone tissue. Primary cultures were transfected with a plasmid in which the Mx-1 promoter drives the expression of SV40 T-antigen when activated by human A/D interferon. Several neomycin (G418)-resistant colonies were characterized for cell growth and alkaline phosphatase (ALP) enzyme activity. The clone, designated OPC1 (osteoblastic precursor cell line 1), which exhibited the highest ALP enzyme activity at passage 10 (P10), was selected for additional osteogenic phenotypic characterization. Reverse transcription-polymerase chain reaction (RT-PCR) phenotyping revealed abundant mRNA for osteocalcin (OC), osteonectin (ON), osteopontin (OP), parathyroid hormone receptor (PTHr), ALP, and procollagen type I (ProI). In addition, the levels of quantitative RT-PCR product of ON, OP, PTHr, and ProI mRNAs exhibited a marked up-regulation when maintained in medium containing an osteogenic supplement (OS). The ability to stimulate osteogenic differentiation was characterized in postconfluent OPC1 cells maintained in tissue culture medium supplemented with recombinant human bone morphogenetic protein-2 (rhBMP-2) either with or without an OS. All treatment groups exhibited a striking up-regulation of ALP enzyme activity that coincided with ALP histochemical observations. Postconfluent cells also exhibited the ability to form mineralized nodules under all treatments (confirmed by von Kossa histochemical staining and calcium deposition). An enzyme immunosorbent assay (EIA) was utilized to measure intact human OC from the OPC1 line under the various treatments. Abundant OC was evident in the tissue culture medium indicating de novo sythesis and release from the OPC1 line under appropriate conditions. The clonal human-derived OPC1 line represents a homogeneous osteogenic cell line that not only has maintained a consistent bone phenotype from P10 to at least P30, but has also exhibited the capacity to generate programmed differentiation in the presence of low dose rhBMP-2 (10 ng/ml). Thus, the OPC1 line is a human-derived osteoprecursor that provides a sensitive in vitro cell culture system to evaluate bone development, cell/biomaterial interactions, and may be a useful screen for putative bone differentiating factors.
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PMID:Establishing an immortalized human osteoprecursor cell line: OPC1. 1049 Dec 20


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