Relationship of c-myc gene copy number and gene expression: cellular effects of elevated c-myc protein.
J Cell Physiol
; 143(2): 372-80, 1990 May.
Article
em En
| MEDLINE
| ID: mdl-2185254
ABSTRACT
The relationship between gene copy number and expression and cellular consequences of elevated levels of c-myc protein has been investigated using recombinant Chinese hamster ovary cell lines transfected with DNA coding for the murine c-myc gene. HC-8 and LC-5 recombinant cells carry approximately 800 and 50 copies of c-myc sequences, respectively, under control of an inducible heat shock promoter. Multivariate flow cytometric analysis and clonogenic assays were used to measure the relationship among c-myc expression, rate of DNA synthesis, and cell survival. Following heat exposure, maximally induced HC-8 cells produced approximately tenfold more c-myc protein than heated LC-5 cells, suggesting a close relationship between gene copy number and level of expression. However, considerable heterogeneity in the level and time of c-myc expression was observed following heat induction, even though the amounts of genomic c-myc were relatively constant. Heterogeneity in gene expression was not attributable to variation in heat induction methodologies and/or cell cycle phase distributions. The presence of high levels of recombinant c-myc protein was associated with a decreased rate of bromodeoxyuridine incorporation into DNA. High levels of c-myc protein in HC-8 cells were inversely correlated with cell survival postheating, suggesting that high levels of c-myc protein are incompatible with cell survival.
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Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Proteínas Proto-Oncogênicas
Limite:
Animals
Idioma:
En
Revista:
J Cell Physiol
Ano de publicação:
1990
Tipo de documento:
Article