Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P02794 (ferritin)
 17,525 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The bovine exocrine pancreatic cell produces a variety of enzymes and proenzymes for export. Biochemical studies by Greene L.J., C.H. Hirs, and G.E. Palade (J. Biol. Chem. 1963. 238:2054) have shown that the mass proportions of several of these proteins in resting pancreatic juice and zymogen granule fractions are identical. In this study we have used immunocytochemical techniques at the electron microscope level to determine whether regional differences exist in the bovine gland with regard to production of individual secretory proteins and whether specialization of product handling occurs at the subcellular level. The technique used is a modification of one previously reported (McLean, J.D., and S.J. Singer. 1970. Proc. Natl. Acad. Sci U.S.A. 69:1771) in which immunocytochemical reagents are applied to thin sections of bovine serum albumin-imbedded tissue and zymogen granule fractions. A double antibody technique was used in which the first step consisted of rabbit F(ab')2 antibovine secretory protein and the detection step consisted of sheep (F(ab')2 antirabbit F(ab')2 conjugated to ferritin. The results showed that all exocrine cells in the gland, and all zymogen granules and Golgi cisternae in each cell, were qualitatively alike with regard to their content of secretory proteins examined (trypsinogen, chymotrypsinogen A, carboxypeptidase A, RNase, and DNase). The data suggest that these secretory proteins are transported through the cisternae of the Golgi complex where they are intermixed before copackaging in zymogen granules; passage through the Golgi complex is apparently obligatory for these (and likely all) secretory proteins, and is independent of extent of glycosylation, e.g., trypsinogen, a nonglycoprotein vs. DNase, a glycoprotein.
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PMID:Immunocytochemical localization of secretory proteins in bovine pancreatic exocrine cells. 31

Apoferritin particles were found in mouse peritoneal macrophages cultured in vitro. They were found as 20S particles in the "ribosomal fraction" of macrophages labeled with L-[14C]glutamic acid. Possibilities that they were breakdown products of ribosomes or of other well-known contaminants of the ribosomal fraction were excluded because they did not incorporate [5-3H]uridine. They were resistant to RNase and were relatively resistant to detergent. The antibody against horse spleen apoferritin precipitated about 70% of the particles in the 20S region, judging by measurement of radioactivity. On in vitro incubation with Fe2+ and suitable oxidizing agents the sedimentation coefficient of 80% of the 20S particles changed to about 60S, which corresponds to that of ferritin. SDS-polyacrylamide gel electrophoresis revealed the presence of subunit structures with the same molecular size as that of mouse liver apoferritin. Under the electron microscope, the particles appeared spherical with a relatively uniform diameter of about 130 A.
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PMID:Synthesis of apoferritin in mouse peritoneal macrophages. Characterization of 20 S particles. 82 42

Interleukin-1 (IL-1 beta) increases the synthesis of both heavy and light (L)-ferritin subunits when added to human hepatoma cells (HepG2) grown in culture. RNase protection and Northern blot analysis with L-ferritin probes revealed that no changes in L-ferritin mRNA levels occur after cytokine stimulation. However, the induction coincides with an increased association of the L-subunit mRNA with polyribosomes. Since the recruitment of stored ferritin mRNA onto polyribosomes is seen when iron enters the cell, the effect of IL-1 beta on iron uptake was tested and was found to be unaffected by the lymphokine. Neither transferrin receptor mRNA levels nor the number of receptors displayed on the cell surface was affected by IL-1 beta. However, the action of the cytokine on ferritin translation is inhibited by the action of the intracellular iron chelator deferoxamine. These data indicate that IL-1 beta induces ferritin gene expression by translational control of its mRNA. The pathway of induction is different from iron-dependent ferritin gene expression whereas regulation requires the background presence of cellular iron.
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PMID:Translational control during the acute phase response. Ferritin synthesis in response to interleukin-1. 169 48

The ferritin iron regulatory element (IRE), a conserved sequence of 28 nucleotides in a hairpin loop, is a conserved mRNA-specific translational regulatory element; flanking the IRE are regions of varying sequence, which form 9-17 base pairs close to the 5' cap. P-90 is a ferritin mRNA-specific translation regulatory protein purified from animal liver and reticulocytes. To study the P-90-RNA interaction, protein nucleases (RNase S1 and T1) and chemical nucleases FeEDTA and/or 1,10-phenanthroline-Cu were used as probes of an oligonucleotide (n = 55), containing the IRE and flanking regions (FL), and natural ferritin mRNA. Footprints and "toeprints" showed that P-90 binding was confined to the stem and loop of the IRE itself. However, P-90 altered the structure of the flanking region by increasing base stacking or helicity (RNase V1 sensitivity). Comparison of the reactivity of the IRE and flanking regions in natural mRNA and the 55-mer showed that long-range interactions included protecting bulges, single-stranded, and stacked regions from protein nucleases as well as stabilizing the P-90-RNA interaction. Structural integration of the IRE with the base-paired flanking regions was indicated by common features of reactivity (periodic hypersensitivity to FeEDTA) and changes in the FL region caused by P-90. The increased secondary structure of the IRE flanking regions caused by P-90 binding to the IRE provides a likely mechanism for blocking initiation of ferritin mRNA translation, since the combined structure (IRE + FL) is so close (8-17 nucleotides) to the cap.
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PMID:Ferritin mRNA: interactions of iron regulatory element with translational regulator protein P-90 and the effect on base-paired flanking regions. 190 35

After exposure to ligand at 0-4 degrees C, estrogen receptors from mouse uteri characteristically eluted between thyroglobulin (Mr 669,000) and ferritin (Mr 443,000) during size-exclusion HPLC. However, when preparations were warmed with ligand under mild activating conditions, most or all of the receptor was observed as a much larger complex, which eluted between dextran blue 2000 and thyroglobulin. Formation of the large complex required ligand, was inhibited by molybdate, and occurred even in 0.4 M KCl. Slower ligand dissociation characterized the large complex, indicating that activated receptors were included preferentially. This large complex did not form when charged cytosols were aged, concentrated, or precipitated, indicating that formation was not the result of random aggregation. After exposure to conditions commonly used for activation (25 degrees C, 60 min), most receptor existed as a very large, monodisperse complex of finite size, predicting an ordered structure for these large complexes that should be useful for defining the types of proteins which can interact with estrogen receptors. Formation of the large complex was not impeded or disrupted by EDTA, RNase, DNase I, thiourea, or mercaptoethanol; however, the capacity to form this large complex was not demonstrated by preparations that had been exposed to trypsin or by the small receptor forms obtained after salt extraction. Proteolytic sensitivity and lack of sensitivity to RNase or DNase indicate that interactions between receptors and other proteins are involved in peak A formation.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Intermolecular engagement of estrogen receptors indicated by the formation of a high molecular weight complex during activation. 251 8

Cancer grows in interaction with the host, that is, a host-tumor relationship exists. Investigations of host factors in patients receiving cancer chemotherapy are important, as they reveal the conditions in which a tumor response can develop. Furthermore, reliable host factors, if present, will be useful for quantitative evaluation of the effects of treatment. We have investigated the following three categories of host factors in relation to the effects of cancer chemotherapy and/or immunotherapy. CBC, and blood chemistries (44 parameters). Tumor markers; sialic acid, RNase, lysozyme, ferritin, IAP (immunosuppressive acidic protein), elastase I, AFP, CEA, POA, CA 19-9, CA 125, etc. Immunological parameters; lymphocyte, active T cell, T cell, B cell, IgG Fc receptor-positive T cell, lymphocyte blastogenesis stimulated by PHA, or concanavalin-A, ADCC activity, interferon production in vitro induced by poly I: C, or PHA, PPD skin test, immune complex, immunoglobulin G, A, and M, OKT series 3, 4, 8, 11, 4/8 ratio, antihuman HLA-DR, Leu 11, NK cell activity, etc. From our clinical observations, there were no significant differences in the pretreatment levels of these parameters between responders and non-responders. In responders, there was a tendency for the host factors to show greater degrees of improvement following treatment than in non-responders, but none proved to be reasonably reliable parameters for evaluating therapeutic effects. On the other hand, from our clinical observations on the advanced gastric cancer cases, life span showed a close correlation with tumor regression induced by cancer chemotherapy. Because of these facts, it is only natural that the clinical effects of chemotherapy are currently determined by definite tumor regression.
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PMID:[Host factors in cancer chemotherapy]. 372 33

A general method for the ultrastructural localization of intracellular proteins and antigens by immunoferritin techniques has been developed. The method involves direct staining of ultrathin sections of mildly glutaraldehyde-fixed and frozen tissues cut by means of a cryo-ultramicrotome. Bovine pancreatic sections were cut, mounted on grids, and stained with ferritin-rabbit antibovine RNase conjugates. After negative staining with 0.2% phosphotungstic acid, electron micrographs revealed specific labeling of all of the zymogen granules and the cisternae of the rough endoplasmic reticulum. No significant labeling was seen in the nucleus, mitochondria, or cell sap regions. The observation that no significant labeling was found in any region of rat pancreatic sections was consistent with the fact that rat RNase is immunologically non-crossreactive with bovine RNase. In addition, the labeling seen in bovine pancreas was completely absent if the sections were first incubated with free antibody. The method used here avoids prolonged fixation, dehydration, and other harsh chemical or physical treatments, and should extend the usefulness of immunoferritin techniques to the intracellular localization of many protein antigens beyond previously available methods.
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PMID:Immunoferritin localization of intracellular antigens: the use of ultracryotomy to obtain ultrathin sections suitable for direct immunoferritin staining. 412 4

Antigens A and B, shown to be associated with the progestagen-dominated human endometrium, were partly purified and their properties studied. The antigens were recovered in the crude nuclei, the heavy particulate fraction and cytosol of decidua-rich tissue from early pregnancy. The antigens in cytosol were enriched by a combination of Concanavalin A-Sepharose chromatography and polyacrylamide gel electrophoresis. The immunological reactivity of the antigens after partial purification by Concanavalin A-Sepharose chromatography was retained after 30 min exposure to 4-85 degrees C at pH 7.4, or after 2 h to pH 2-12 at 22 degrees C. Trypsin, but not pepsin, RNase, DNase or neuraminidase, completely destroyed immunological reactivity of both antigens. The apparent molecular weight of both antigens determined by filtration on Sephadex G100 was 48 000. The isoelectric point of both antigens was approximately 4.9. The antigens were not immunologically related to transferrin, ceruloplasmin, alpha-1-antitrypsin, ferritin, uteroglobin, alpha-fetoprotein, human chorionic gonadotrophin, pregnancy-associated plasma proteins or pregnancy zone protein. Furthermore, the antisera to Antigens A and B did not react with the decidual cytosol of pregnant baboons or of pseudopregnant rats.
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PMID:Properties of the progestagen-dependent protein of the human endometrium. 743 Dec 86

Ferritin and transferrin receptors are co-ordinately regulated by the same RNA-protein interaction: the conserved iron regulatory element (IRE) in mRNA and the IRE-binding protein (IRE-BP/IRP/FRP/P-90). The 28 nucleotide IRE in ferritin mRNA is a single copy, with base-paired flanking regions (FL), located near the 5' cap. In the transferrin receptor mRNA, the IRE is located in the 3' untranslated region, as five variable copies and lacking predicted base-paired flanking regions; an alternate predicted structure without IREs has similar stability. When iron is scarce, ferritin mRNA does not form polyribosomes whereas the transferrin receptor mRNA is translated; when iron is abundant, ferritin mRNA forms polyribosomes and the transferrin receptor mRNA is degraded. To investigate structures which contribute to differences in the regulation of the two mRNAs, the effect of mutation of the ferritin FL was studied. Changes in structure (changes in reactivity with RNase V1 and RNase S1. Fe-bleomycin) and changes in function (translation in rabbit reticulocyte extracts) were compared for mutant and wild-type FL sequences in ferritin mRNA. The disruption of a triplet of base-pairs in the FL had diminished regulation; a second mutation to restore the triplet base-pairs conferred wild-type translational regulation. Conformation of the mutant RNA-IRE-BP complex was also different. We show that the triplet of base-pairs is conserved; the triplet is also the location of IRE-BP-dependent conformational changes in the FL structure previously observed. Increasing FL base-pairs had no effect on function. Structural changes associated with altered function included bleomycin sites in the IRE, suggesting an alternate conformation of the hairpin, and different base-stacking (V1 sensitivity) in the FL. The function of the FL, which is altered by mutation of phylogenetically conserved triplet base-pairs, may be enhancement of formation of a particular IRE stem-loop-protein interaction.
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PMID:The influence of the base-paired flanking region on structure and function of the ferritin mRNA iron regulatory element. 768 92

The abundance of insulin-like growth factor I (IGF-I) messenger RNA (mRNA) is decreased in the liver of fasting, protein-restricted, and energy-restricted rats. The extent to which this decrease in steady state mRNA abundance may be attributed to a decrease in IGF-I gene transcription remains unresolved. In the present study, we used an RNase protection assay to quantify IGF-I nuclear transcript (pre-mRNA) and mRNA abundance in whole cellular RNA isolated from liver of fasted and nonfasted male rats (4-6 weeks of age). The results of the RNase protection assay of IGF-I nuclear transcripts were strongly correlated with the results of nuclear transcription elongation (run-on) assays (r > 0.90; P < 0.001). In addition, the RNase protection assay allows for a greater capability for sensitively monitoring gene transcription in a large number of samples. In four different experiments, a consistent decrease in the quantity of IGF-I nuclear transcripts was observed in liver of animals fasted for 72 h, whereas IGF-I pre-mRNA abundance in animals fed ad libitum was highly variable (average intraassay coefficient of variation = 74% vs. 34% for nonfasted and fasted groups). When data from the four experiments were pooled, fasting reduced IGF-I pre-mRNA and mRNA levels by 78% and 70% (P < 0.001), respectively. Fasting also caused a significant decrease in mRNA and nuclear transcript abundance for another nutritionally sensitive gene, the gene encoding transthyretin (TTR). To determine whether the decrease in IGF-I and TTR nuclear transcripts was gene specific, levels of nuclear transcripts for serum albumin, H-ferritin, and ribosomal RNA were also quantified. The results indicated that serum albumin, H-ferritin, and ribosomal RNA nuclear transcripts were not decreased by fasting, demonstrating that the negative effect of fasting was specific for IGF-I and TTR. In summary, these results indicate that IGF-I and TTR nuclear transcripts are specifically decreased by fasting. The decrease in IGF-I mRNA is matched by a similar decrease in IGF-I nuclear transcripts, suggesting that fasting controls IGF-I gene expression primarily at the transcriptional level.
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PMID:The effect of fasting on insulin-like growth factor-I nuclear transcript abundance in rat liver. 829 71


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