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Autor     C.N. Lok, T.T. Loh
Titel    Regulation of Transferrin Function and Expression: Review and Update
Zeitschrift    Biological Signals Receptors
Verlag    Karger
Ausgabe    7
Jahr    1998
Seiten    157–178
Anmerkung    Im Text und im Inhaltsverzeichnis wird eine andere Publikation der beiden Autoren angegeben [1]. Dort finden sich aber die Textparallelen nicht.
URL    http://www.karger.de/Article/Pdf/14542

Literaturverz.   

nein
Fußnoten    nein
Fragmente    3


Fragmente der Quelle:
[1.] Src/Fragment 024 03 - Diskussion
Zuletzt bearbeitet: 2014-09-27 20:22:20 Kybot
Fragment, Lok and Loh 1998, SMWFragment, Schutzlevel, Src, Verschleierung, ZuSichten

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Untersuchte Arbeit:
Seite: 24, Zeilen: 3-9, 12-22, 24-28
Quelle: Lok and Loh 1998
Seite(n): 163, 164, Zeilen: 163: 2. Spalte: 30ff; 164: 1. Spalte: 6ff
[...] oligodendrocytes are believed to be the predominant iron-containing cells in the brain and have a special requirement of iron for myelin production, and immature oligodendrocytes express TfR for iron acquisition (Connor, J.R., Menzies, S.L.et al, 1996). In normal brain, TfR immunostaining is detected primarily in endothelial and glial cells, whereas neoplastic cells from nearly all brain tumors are found to be TfR-positive (Recht, L., C.O.et al, 1990, Prior, R. et al, 1990) [...]

[...]

Most malignant and proliferating cells express high numbers of TfRs as compared to their normal and quiescent counterparts and the first direct evidence of the proliferation-associated expression of TfR was demonstrated in several lymphoblastoid cell lines and activated peripheral blood lymphocytes which have high numbers of transferrin binding sites (Larrick, J.W. et al, 1979). Subsequently, numerous reports (Kuhn, L.C. et al, 1990, Neckers, L.M. et al, 1991) confirmed that virtually all cell lines and normal proliferating cells possess high numbers of TfRs, TfR expression increases upon mitogenic stimulation and diminishes upon terminal differentiation and growth arrest and furthermore anti-TfR antibodies that can block transferrin binding and hence iron uptake inhibit cell proliferation (Trowbridge, I.S. et al, 1982). In some tumors like in breast cancers TfR has been discussed to have growth factor like functions (Cavanaugh et al 1999) which will support the notion that the TfR is a proliferation-associated marker. The explanation for the proliferation-associated expression of TfR is attributed in part to an increased requirement of iron for synthesis and functioning of numerous iron-containing proteins, in particular ribonucleotide reductase, which is a rate-limiting enzyme in DNA synthesis (Chitambar, C.R. et al, 1995).

The oligodendrocytes are believed to be the predominant iron-containing cells in the brain and have a special requirement of iron for myelin production, and immature oligodendrocytes express TfR for iron acquisition [82].

[Seite 164]

In normal brain, TfR immunostaining is detected primarily in endothelial and glial cells, whereas neoplastic cells from nearly all brain tumors are found to be TfR-positive [84, 85].

[...]

Not only tissues such as reticulocytes and placenta, but also most malignant and proliferating cells express high numbers of TfRs as compared to their normal and quiescent counterparts. The first direct evidence of the proliferation-associated expression of TfR was demonstrated in several lymphoblastoid cell lines and activated peripheral blood lymphocytes which have high numbers of transferrin binding sites [92]. Subsequently, numerous reports [93, 94] confirmed that (1) virtually all cell lines and most normal proliferating cells examined possess high numbers of TfRs, (2) TfR expression increases upon mitogenic stimulation and diminishes upon terminal differentiation and growth arrest, (3) the proliferation-associated antigens (cluster of differentiation, CD 71) present on lymphocytes are the TfR [5] and (4) anti-TfR antibodies that can block transferrin binding and hence iron uptake inhibit cell proliferation [95]. These observations, together with studies showing that iron deprivation prevents DNA synthesis [96, 97] and that transferrin is essential for in vitro cell growth in serum-free systems [98], support the notion that the TfR is a proliferation-associated marker. The explanation for the proliferation-associated expression of TfR is attributed in part to an increased requirement of iron for synthesis and functioning of numerous iron-containing proteins, in particular ribonucleotide reductase, which is a rate-limiting enzyme in DNA synthesis [99, 100].


82 Connor JR, Menzies SL: Relationship of iron to oligodendrocytes and myelination. Glia 1996;17:83–93.

84 Recht L, Torres CO, Smith TW, Raso V, Griffin TW: Transferrin receptor in normal and neoplastic brain tissue: Implications for braintumor immunotherapy. J Neurosurg 1990;72:941–945.

85 Prior R, Reifenberger G, Wechsler W: Transferrin receptor expression in tumour of the human nervous system: Relation to tumour type, grading and tumour growth fraction. Virchows Arch A Pathol Anat Histopathol 1990;416:491–496.

92 Larrick JW, Cresswell P: Modulation of cell surface iron transferrin receptors by cellular density and state of activation. J Supermol Struct 1979;11:579–586.

93 Kuhn LC, Schulman HM, Ponka P: Iron-transferrin requirements and transferrin receptor expression in proliferating cells; in Ponka, Schulman, Woodworth (eds): Iron Transport and Storage. Boca Raton, CRC Press, 1990, pp 149–191.

94 Neckers LM: Regulation of transferrin receptor expression and control of cell growth. Pathobiology 1991; 59:11–18.

95 Trowbridge IS, Lopez F: Monoclonal antibody to transferrin receptor blocks transferrin binding and inhibits human tumor cell growth in vitro. Proc Natl Acad Sci USA 1982; 79:1175–1179.

96 Hoffbrand AV, Graneshaguru K, Hooton JWL, Tattersall MHN: Effect of iron deficiency and desferrioxamine on DNA synthesis in human cells. Br J Haematol 1976;33: 517–526.

97 Fernandez-Pol JA, Bono VH Jr, Johnson GS: Control of growth by picolinic acid: Differential response of normal and transformed cells. Proc Natl Acad Sci USA 1977;74:2889–2893.

98 Barnes D, Sato G: Serum-free cell culture: A unifying approach. Cell 1980;22:649–655.

99 Eriksson S, Graslund A, Skog S, Thelander L, Tribukait B: Cell cycle- dependent regulation of mammalian ribonucleotide reductase. J Biol Chem 1984;259:11695– 11700.

100 Chitambar CR, Wereley JP: Effect of hydroxyurea on cellular iron metabolism in human leukemic CCRF-CEM cells: Changes in iron uptake and the regulation of transferrin receptor and ferritin gene expression following inhibition of DNA synthesis. Cancer Res 1995; 55:4361–4366.

Anmerkungen

Ein Verweis auf die Quelle fehlt.

Auch die meisten Literaturverweise sind übernommen.

Sichter
(Hindemith)

[2.] Src/Fragment 025 02 - Diskussion
Zuletzt bearbeitet: 2014-09-27 20:22:22 Kybot
Fragment, Lok and Loh 1998, SMWFragment, Schutzlevel, Src, Verschleierung, ZuSichten

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Untersuchte Arbeit:
Seite: 25, Zeilen: 2-19
Quelle: Lok and Loh 1998
Seite(n): 166, 167, 168, Zeilen: 166: l. Spalte: 2ff; 167: r. Spalte: 8ff; 168: Abbildung
Kuhn and coworkers reported the first genomic clone for the transferrin receptor by expression and cloning techniques (Kuhn, L.C. et al, 1984). The human TfR gene was found to contain at least 19 exons distributed over 31 kb of DNA and contains a translated region of 2,280 nucleotides in their respective cDNA clones.

TfR gene transcription is activated during cell proliferation (Seiser, C. et al, 1993), cell transformation (Beard, P. et al, 1991) and differentiation of immature erythroid cells to hemoglobin synthesizing cells (Chan, R.Y.Y. et al, 1994, Chan, L.N. et al, 1992). On the other hand, gene transcription is comparatively inactive in the quiescent state of the cells, that is during growth arrest and terminal differentiation in the nonerythroid cells (Lok, C.N. et al, 1996). TfR gene transcription is believed to be controlled by cellular signals involved in the cell growth and differentiation, resulting in the expression of TfR for iron demand during cell proliferation or heme synthesis. The TfR gene promoter region (fig. 1.10) is GC-rich and contains a TATA box about 30 bp upstream from the known transcriptional start site. A consensus SP-1/GC-rich sequence is located near the TATA box and a sequence as short as 47 bp upstream of the transcriptional start site has been found to be sufficient for driving the basal transcription of the reporter gene as shown by reporter gene assays (Owen, D. et al, 1987).

Scr 025a diss.png

Fig. 2.5. TfR gene promoter region. Part of the TfR promoter region that is critical for its expression. The underlined sequences represent elements similar to certain consensus cisacting elements. Sequence similarity to consensus regulatory cis-elements and putative binding factors are indicated (see text for explanation). Bold typeface identifies bases identical to the TfR gene elements (Sieweke, M.H. et al, 1996, Ouyang, Q. et al, 1993, Roberts, M.R. et al, 1994). CRE = cAMP-responsive element; CREB = CREbinding protein; PSE = proximal sequence element.

By expression cloning techniques, Schneider and coworkers first isolated cDNA clones of TfR in MOLT-4 cells, and later Kuhn and coworkers [8] reported the first genomic clone for the receptor. The human TfR gene was found to contain at least 19 exons distributed over 31 kb of DNA. Both groups reported a translated region of 2,280 nucleotides in their respective cDNA clones.

[Seite 167]

In general, the gene transcription is activated during cell proliferation [120, 130, 131, 146], cell transformation [147] and differentiation of immature erythroid cells to hemoglobinsynthesizing cells [41, 45]. On the other hand, gene transcription is comparatively inactive in the quiescent state of the cells, that is during growth arrest and terminal differentiation in the nonerythroid cells [148–150]. TfR gene transcription is believed to be controlled by cellular signals involved in the cell growth and differentiation, resulting in the expression of TfR for iron demand during cell proliferation or heme synthesis.

[...] The TfR gene promoter region (fig. 3) is GC-rich and contains a TATA box about 30 bp upstream from the known transcriptional start site. A consensus SP-1/GC-rich seqence is located near the TATA box. [...] By reporter gene assays, a sequence as short as 47 bp upstream of the transcriptional start site has been found to be sufficient for driving the basal transcription of the reporter gene [121].

[Seite 168]

Scr 025a source.png

Fig. 3. TfR gene promoter region. Part of the TfR promoter region that is critical for its expression. The underlined sequences represent elements similar to certain consensus cisacting elements. Sequence similarity to consensus regulatory cis-elements and putative binding factors are indicated (see text for explanation). Bold typeface identifies bases identical to the TfR gene elements [46, 151, 154]. CRE = cAMP-responsive element; CREB = CREbinding protein; PSE = proximal sequence element.


8 Kuhn LC, McClelland A, Ruddle FH: Gene transfer, expression and molecular cloning of the human transferrin receptor gene. Cell 1984; 37:95–103.

41 Chan RYY, Seiser C, Schulman HM, Kuhn LC, Ponka P: Regulation of transferrin receptor mRNA expression: Distinct regulatory features in erythroid cells. Eur J Biochem 1994;220:683–692.

45 Chan LN, Gerhardt EM: Transferrin receptor gene is hyperexpressed and transcriptionally regulated in differentiating erythroid cells. J Biol Chem 1992;267:8254–8259.

121 Owen D, Kuhn LC: Noncoding 3) sequences of the transferrin receptor gene are required for mRNA regulation by iron. EMBO J 1987; 6:1287–1293.

130 Seiser C, Teixeira S, Kuhn LC: Interleukin-2-dependent transcriptional and post-transcriptional regulation of transferrin receptor mRNA. J Biol Chem 1993;268: 13074–13080.

131 Casey JL, Di Jeso B, Rao K, Klausner RD, Harford JB: Two genetic loci participate in the regulation by iron of the gene for the human transferrin receptor. Proc Natl Acad Sci USA 1988;85:1787– 1791.

146 Kronke M, Leonard W, Depper JM, Greene WC: Sequential expression of genes involved in human T lymphocyte growth and differentiation. J Exp Med 1985;161: 1593–1598.

147 Beard P, Offord E, Paduwat N, Bruggmann H: SV40 activates transcription from the transferrin receptor promoter by inducing a factor which binds to the CRE/AP- 1 recognition sequence. Nucleic Acids Res 1991;25:7117–7123.

148 Alcantara O, Denham CA, Phillips JL, Boldt DH: Transcriptional regulation of transferrin receptor expression by cultured lymphoblastoid T cells treated with phorbol esters. J Immunol 1989;142:1719– 1725.

149 Trepel JB, Colamonici OR, Kelly K, Schwab G, Watt RA, Sauville EA, Jaffe ES, Neckers LM: Transcriptional inactivation of c-myc and the transferrin receptor in dibutyryl cyclic AMP-treated HL-60 cells. Mol Cell Biol 1987;7:2644– 2648.

150 Lok CN, Chan KF, Loh TT: Transcriptional regulation of transferrin receptor gene expression during phorbol ester-induced HL-60 cell differentiation: Evidence for a negative regulatory role of the phorbol ester-responsive elementlike sequence. Eur J Biochem 1996;236:614–619.

151 Ouyang Q, Bommakanti M, Miskimins WK: A mitogen-responsive promoter region that is synergistically activated through multiple signalling pathways. Mol Cell Biol 1993;13:1796–1804.

154 Roberts MR, Han Y, Fienberg A, Hunihan L, Ruddle FH: A DNAbinding activity, TRAC, specific for the TRA element of the transferrin receptor gene copurifies with the KU autoantigen. Proc Natl Acad Sci USA 1994;91:6354–6358.

Anmerkungen

Ein Verweis auf die Quelle fehlt.

Auch die meisten Literaturverweis sind übernommen.

"fig. 1.10" existiert in der untersuchten Arbeit nicht. Gemeint ist wohl Abbildung 2.5., denn diese entspricht der Abbildung 3 der Quelle.

Sichter
(Hindemith)

[3.] Src/Fragment 026 01 - Diskussion
Zuletzt bearbeitet: 2014-09-27 20:22:23 Kybot
Fragment, KomplettPlagiat, Lok and Loh 1998, SMWFragment, Schutzlevel, Src, ZuSichten

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Untersuchte Arbeit:
Seite: 26, Zeilen: 1-9
Quelle: Lok and Loh 1998
Seite(n): 169, Zeilen: l. Spalte: 27ff
One of the most important transcriptional control mechanisms of the TfR is the upregulation of the receptor expression in developing erythroid cells. In an avian erythroblastic cell line, the transcription factor Ets-1 could stimulate the erythroid differentiation and was also found to enhance the TfR promoter activity by 2- to 3-fold via an Ets binding site close to the TRE-like sequence (Sieweke, M.H. et al, 1996). Interestingly, overexpression of Maf B, a direct repressor of Ets-1, downregulated the TfR expression and inhibited the erythroid differentiation, without affecting cell growth (Sieweke, M.H. et al, 1996). Therefore, an erythroid-specific transcriptional control of the TfR seems to operate. One of the most important transcriptional control mechanisms of the TfR is the upregulation of the receptor expression in developing erythroid cells. In an avian erythroblastic cell line, the transcription factor Ets-1 could stimulate the erythroid differentiation and was also found to enhance the TfR promoter activity by 2- to 3-fold via an Ets binding site close to the TRE-like sequence [46]. Interestingly, overexpression of Maf B, a direct repressor of Ets-1, downregulated the TfR expression and inhibited the erythroid differentiation, without affecting cell growth [46]. Therefore, an erythroid-specific transcriptional control of the TfR seems to operate.

46 Sieweke MH, Tekotte H, Frampton J, Graf T: MafB is an interaction partner and repressor of Ets-1 that inhibits erythroid differentiation. Cell 1996;85:49–60.

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