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Expression of exogenous c ‐ myc oncogene does not initiate DNA synthesis in primary rat hepatocyte cultures
Author(s) -
Skouteris George G.,
Kaser Matthew R.
Publication year - 1992
Publication title -
journal of cellular physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.529
H-Index - 174
eISSN - 1097-4652
pISSN - 0021-9541
DOI - 10.1002/jcp.1041500219
Subject(s) - dna synthesis , hepatocyte , biology , microbiology and biotechnology , mitosis , dna , transfection , epidermal growth factor , cell cycle , hepatocyte growth factor , cell culture , gene , biochemistry , in vitro , genetics , receptor
Cultured hepatocytes from adult rats stimulated with combinations of growth factors enter into S phase but do not undergo multiple rounds of DNA synthesis nor mitosis. We have examined the potential of an introduced oncogene to induce alterations in the DNA synthetic activity of the cultured hepatocytes in response to epidermal growth factor (EGF). Overexpression of c ‐ myc did not initiate significant DNA synthesis in rat hepatocyte cultures alone, although it cooperated with added EGF to super‐induce thymidine incorporation into DNA. From our results, it is suggested that EGF is also necessary to initiate hepatocyte DNA synthesis probably by inducing a battery of cell cycle‐related genes if incubated with c ‐ myc transfected cultures for only 5 hours. Hepatocyte polypeptides reacting with antiMYC antisera were found to migrate between 55–67 KDa in SDS‐PAGE; only the 64–67 KDa species were found to be phosphorylated, and the observed size heterogeneity may be due to proteolytic degradation or may reflect presently unknown posttranslational modifications.