Members of the poly (rC) binding protein family stimulate the activity of the c-myc internal ribosome entry segment in vitro and in vivo
The 5′ untranslated region of the proto-oncogene c- myc contains an internal ribosome entry segment and c-Myc translation can be initiated by cap-independent as well as cap-dependent mechanisms. In contrast to the process of cap-dependent initiation, the trans -acting factor requirements for cellula...
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Veröffentlicht in: | Oncogene 2003-09, Vol.22 (39), p.8012-8020 |
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Format: | Artikel |
Sprache: | eng |
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Zusammenfassung: | The 5′ untranslated region of the proto-oncogene c-
myc
contains an internal ribosome entry segment and c-Myc translation can be initiated by cap-independent as well as cap-dependent mechanisms. In contrast to the process of cap-dependent initiation, the
trans
-acting factor requirements for cellular internal ribosome entry are poorly understood. Here, we show that members of the poly (rC) binding protein family, poly (rC) binding protein 1 (PCBP1), poly (rC) binding protein 2 (PCBP2) and hnRNPK were able to activate the IRES
in vitro
up to threefold when added in combination with upstream of N-ras and unr-interacting protein. The interactions of PCBP1, PCBP2 and hnRNPK with c-
myc
-IRES-RNA were shown to be specific by ultraviolet crosslinking analysis and electrophoretic mobility shift assays, while immunoprecipitation of the three proteins using specific antibodies followed by reverse transcriptase–polymerase chain reaction showed that they were able to bind c-
myc
mRNA. c-
myc
–IRES-mediated translation from the reporter vector was stimulated by cotransfection of plasmids encoding PCBP1, PCBP2 and hnRNPK. Interestingly, the mutated version of the c-
myc
IRES that is prevalent in patients with multiple myeloma bound hnRNPK more efficiently
in vitro
and was stimulated by hnRNPK to a greater extent
in vivo
. |
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ISSN: | 0950-9232 1476-5594 |
DOI: | 10.1038/sj.onc.1206645 |