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Post‐transcriptional repression of thymidine kinase expression during cell cycle and growth stimulation
Author(s) -
Mikulits Wolfgang,
Müllner Ernst W.
Publication year - 1994
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(94)00451-x
Subject(s) - thymidine kinase , psychological repression , transfection , microbiology and biotechnology , stimulation , biology , cell growth , dna synthesis , thymidine , gene expression , endogeny , complementary dna , expression vector , gene , dna , endocrinology , biochemistry , recombinant dna , genetics , virus , herpes simplex virus
In vertebrates, endogenous thymidine kinase (TK) gene expression is strictly growth‐dependent. Here we report that in continuously cycling Ltk − mouse fibroblasts, stably transfected with a vector expressing human TK cDNA from a constitutive promoter, enzyme activity rises 8‐fold at the G 1 /S phase transition and declines again in G 2 . The mechanism did not involve changes in protein stability. When hTK was put under the control of a hormone‐inducible promoter, production of high mRNA levels following addition of dexamethasone did not result in any enzyme activity in resting NIH‐3T3tk − cells. After growth stimulation with serum, TK activity rose together with the onset of DNA synthesis only in the simultaneous presence of the hormone.