c-myc expression is activated by the immunoglobulin kappa-enhancers from a distance of at least 30 kb but not by elements located within 50 kb of the unaltered c-myc locus in vivo.
50 kb of contiguous DNA sequences covering the human c-myc coding region and approximately 20 kb of flanking upstream and downstream sequences were cloned onto a prokaryotic F-factor derived plasmid, which also contains a selectable marker and the plasmid origin of DNA replication oriP of Epstein Barr virus (EBV). Since these plasmids replicate extrachromosomally after stable transfection into EBV-positive B-cell lines, the gene regulation of c-myc can be analysed independent from chromosomal integration positions. Despite the presence of all known c-myc regulatory elements on these constructs, expression from the stably transfected c-myc gene was barely detectable in either cell line. Hypermethylation of these plasmids could be excluded as a mechanism for the lack of gene expression. Insertion of the immunoglobulin kappa-intron and 3' enhancers, however, activated c-myc transcription, when placed adjacent to or separated from the c-myc promoters by as far as 30 kb. These results indicate that transcription of c-myc in vivo requires additional and still unidentified control elements located outside this 50 kb fragment, and experimentally demonstrate long range enhancer function in vivo.
Mautner
J
J
Institut für Klinische Molekularbiologie und Tumorgenetik, GSF-Forschungszentrum für Umwelt und Gesundheit GmbH, München, Germany.
Behrends
U
U
Hörtnagel
K
K
Brielmeier
M
M
Hammerschmidt
W
W
Strobl
L
L
Bornkamm
G W
GW
Polack
A
A
D001483:Base Sequence; D002051:Burkitt Lymphoma / Q000235:genetics*; D002461:Cell Line, Transformed; D002843:Chromatin / Q000502:physiology; D002877:Chromosomes, Human; D004273:DNA, Neoplasm / Q000235:genetics; D015226:Dinucleoside Phosphates / Q000378:metabolism; D004742:Enhancer Elements, Genetic; D015972:Gene Expression Regulation, Neoplastic; D016259:Genes, myc; D004854:Herpesvirus 4, Human; D006801:Humans; D007145:Immunoglobulin kappa-Chains / Q000235:genetics* / Q000502:physiology; D007438:Introns; D008745:Methylation; D008969:Molecular Sequence Data; D010957:Plasmids / Q000235:genetics; D011401:Promoter Regions, Genetic; D014162:Transfection
D002843:Chromatin; D004273:DNA, Neoplasm; D015226:Dinucleoside Phosphates; D007145:Immunoglobulin kappa-Chains