Relationship of c‐myc gene copy number and gene expression: Cellular effects of elevated c‐myc protein

M. G. Pallavicini, C. Rosette, M. Reitsma, P. S. Deteresa, J. W. Gray

Research output: Contribution to journalArticle

15 Scopus citations

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 reatively 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.

Original languageEnglish (US)
Pages (from-to)372-380
Number of pages9
JournalJournal of Cellular Physiology
Volume143
Issue number2
DOIs
StatePublished - May 1990

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ASJC Scopus subject areas

  • Physiology
  • Clinical Biochemistry
  • Cell Biology

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