Growth-regulated expression of vimentin in hamster fibroblasts is a result of increased transcription.
We have previously shown that vimentin is a growth-regulated gene whose mRNA levels increase after serum stimulation of quiescent hamster fibroblasts. In this study, the control of the growth-regulated expression of vimentin was determined in ts13 cells induced to proliferate by serum. Both transcriptional and post-transcriptional mechanisms of regulation were examined by determining transcriptional rates, cytoplasmic transcript abundance, transcript stability, and protein abundance. We observed a fourfold increase in vimentin transcripts in the cytoplasm of serum-stimulated ts13 cells. Since transcripts are stable in both quiescent and stimulated cells, this induction of vimentin expression is a result of a fivefold increase in vimentin-specific transcriptional activity. As a result of this increased transcript availability, the abundance of polymerized vimentin protein increased following serum stimulation of quiescent fibroblasts. Overall, the induction of vimentin expression in fibroblasts by serum is a consequence of increased vimentin-specific transcriptional activity. The significance of this with regard to cytoskeletal organization and cell division is discussed.
Ferrier
A F
AF
T.H. Morgan School of Biological Sciences, University of Kentucky, Lexington 40506-0225.
Hirschhorn
R R
RR
D000818:Animals; D002453:Cell Cycle; D002467:Cell Nucleus / Q000502:physiology; D006224:Cricetinae; D003593:Cytoplasm / Q000378:metabolism; D015870:Gene Expression; D066298:In Vitro Techniques; D008647:Mesocricetus; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D014158:Transcription, Genetic; D014746:Vimentin / Q000235:genetics / Q000378:metabolism*
D012333:RNA, Messenger; D014746:Vimentin