Distinct nuclear arrangement of active and inactive c-myc genes in control and differentiated colon carcinoma cells.
Using sequential RNA-DNA fluorescence in situ hybridization, the nuclear arrangement of both the active and inactive c-myc gene as well as its transcription was investigated in colon cancer HT-29 cells induced to differentiate into enterocytes. Cytogenetic studies revealed the presence of two chromosomes 8 in HT-29 cells, of which the one containing c-myc gene amplicons was substantially larger and easily distinguished from the normal chromosome. This observation enabled detection of both activity and nuclear localization of c-myc genes in single cells and in individual chromosome territories. Similar transcriptional activity of the c-myc gene was observed in both the normal and derivative chromosome 8 territories showing no influence of the amplification on the c-myc gene expression. Our experiments demonstrate strikingly specific nuclear and territorial arrangements of active genes as compared with inactive ones: on the periphery of their territories facing to the very central region of the cell nucleus. Nuclear arrangement of c-myc genes and transcripts was conserved during cell differentiation and, therefore, independent of the level of differentiation-specific c-myc gene expression. However, after the induction of differentiation, a more internal territorial location was found for the single copy c-myc gene of normal chromosome 8, while amplicons conserved their territorial topography.
Harnicarová
Andrea
A
Laboratory of Molecular Cytology and Cytometry, Institute of Biophysics, Academy of Sciences of the Czech Republic, Královopolská 135, 612 65 Brno, Czech Republic.
Kozubek
Stanislav
S
Pacherník
Jirí
J
Krejci
Jana
J
Bártová
Eva
E
D000230:Adenocarcinoma / Q000378:metabolism*; D001386:Azides; D014408:Biomarkers, Tumor / Q000032:analysis*; D002454:Cell Differentiation; D045744:Cell Line, Tumor; D002467:Cell Nucleus; D049109:Cell Proliferation; D002898:Chromosomes, Human, Pair 8 / Q000378:metabolism*; D003110:Colonic Neoplasms / Q000378:metabolism*; D020895:Enterocytes / Q000502:physiology; D018628:Gene Dosage; D017491:Genes, APC; D016259:Genes, myc; D006801:Humans; D016271:Proto-Oncogene Proteins c-myc / Q000378:metabolism*; D014158:Transcription, Genetic
D001386:Azides; D014408:Biomarkers, Tumor; D016271:Proto-Oncogene Proteins c-myc; C029534:hydroxysuccinimidyl-4-azidobenzoate