Altered expression of the twist gene in young versus senescent human diploid fibroblasts.
We have recently reported the cloning and characterization of the human twist gene (H-twist), which encodes an evolutionarily conserved helix-loop-helix transcription factor. In several species, twist has been shown to play a role in mesoderm differentiation. We now report on the differential expression of H-twist as a function of in vitro life span in human diploid fibroblasts. H-twist was found to be expressed at a relatively high level in quiescent young cells. Addition of fresh serum to young G0 cultures results in a rapid repression of H-twist mRNA expression. This repression depends on the presence of growth factors, specifically EGF, and requires protein synthesis. mRNA stability studies using either actinomycin D or alpha-amanitin indicate a similar decay rate of H-twist mRNA in both young and senescent cells, suggesting that the differential expression of H-twist in young versus old is not primarily regulated at the level of mRNA turnover.
Wang
S M
SM
Center for Gerontological Research, The Medical College of Pennsylvania and Hahnemann University, Philadelphia 19129, USA.
Phillips
P D
PD
Sierra
F
F
Cristofalo
V J
VJ
D002460:Cell Line; D016922:Cellular Senescence / Q000235:genetics; D003470:Culture Media; D004171:Diploidy; D004815:Epidermal Growth Factor / Q000494:pharmacology; D005347:Fibroblasts / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D015870:Gene Expression / Q000187:drug effects; D006207:Half-Life; D006801:Humans; D009687:Nuclear Proteins / Q000235:genetics*; D011500:Protein Synthesis Inhibitors / Q000494:pharmacology; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D016192:Resting Phase, Cell Cycle / Q000235:genetics; D014157:Transcription Factors; D051879:Twist-Related Protein 1
D003470:Culture Media; D009687:Nuclear Proteins; D011500:Protein Synthesis Inhibitors; D012333:RNA, Messenger; C103173:TWIST1 protein, human; D014157:Transcription Factors; D051879:Twist-Related Protein 1; D004815:Epidermal Growth Factor