Single-cell c-myc gene expression in relationship to nuclear domains.
Nuclear locations of the c-myc gene and its transcripts (c-myc (T)) have been investigated in relation to nuclear domains involved in RNA synthesis and processing. Transcription of the c-myc gene appears to be linked to the late G(1)- and preferentially to S-phases of the cell cycle. The c-myc gene and its transcripts were positioned non-randomly within the interphase nucleus; additionally, c-myc RNA signals accumulated at nucleoli. Using oligo-probes, designed to exon II and exon III of the c-myc gene, single c-myc (T) was preferentially observed in human carcinoma HT29 and A549 cells. Conversely, human embryonal teratocarcinoma NTERA cells were characterized by the presence of multiple c-myc RNA signals located in both the nucleoli and nucleoplasm. When accumulated at nucleoli, c-myc (T) occupied the periphery of this organelle, though not those associated with the cultivation surface. In HT29 cells, approximately 80% of c-myc (T) co-localized with the RNAP II positive regions, so-called transcription factories. However, in approximately 20% of the cells with c-myc transcripts, the c-myc (T) was released from the site of synthesis, and was not associated with either transcription factories or SC35 domains. In approximately 60% of nuclei with c-myc (T), these signals were located in close proximity to the SC35 regions, but promyelocytic leukaemia bodies were associated with c-myc (T) only in approximately 20% of the nuclei. Taken together, c-myc RNA signals were positioned in the most internal parts of the cell nuclei preferentially associated with the nucleoli. Specific nuclear and nucleolar positioning probably reflects the kinetics of c-myc RNA metabolism.
Bártová
Eva
E
Institute of Biophysics, Academy of Sciences of the Czech Republic, Královopolská 135, CZ-612 65, Brno, Czech Republic. bartova@ibp.cz
Harnicarová
Andrea
A
Krejcí
Jana
J
Strasák
Ludek
L
Kozubek
Stanislav
S
D002467:Cell Nucleus / Q000235:genetics / Q000378:metabolism / Q000648:ultrastructure*; D002898:Chromosomes, Human, Pair 8; D015870:Gene Expression; D016259:Genes, myc; D019073:HT29 Cells; D006801:Humans; D016271:Proto-Oncogene Proteins c-myc / Q000378:metabolism; D012319:RNA Polymerase II / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D014018:Tissue Distribution; D014158:Transcription, Genetic; D014407:Tumor Cells, Cultured
C489427:MYC protein, human; D016271:Proto-Oncogene Proteins c-myc; D012333:RNA, Messenger; D012319:RNA Polymerase II