Multiple mechanisms regulate the proliferation-specific histone gene transcription factor HiNF-D in normal human diploid fibroblasts
Graduate School of Biomedical Sciences; Department of Cell Biology
Medical Subject Headings
Blood; Cell Division; Cell Nucleus; DNA; *Diploidy; Fibroblasts; Histones; Humans; Transcription Factors; Transcription, Genetic
Life Sciences | Medicine and Health Sciences
The proliferation-specific transcription factor complex HiNF-D interacts with sequence specificity in a proximal promoter element of the human H4 histone gene FO108, designated Site II. The occupancy of Site II by HiNF-D has been implicated in proper transcription initiation and as a component of the cell cycle regulation of this gene. In the present study we have investigated the role of the HiNF-D/Site II interaction in controlling the level of H4 histone gene transcription during modifications of normal cellular growth. HiNF-D binding activity is present at high levels in rapidly proliferating cultures of human diploid fibroblasts and is reduced to less than 2% upon the cessation of proliferation induced by serum deprivation of sparsely population fibroblast cultures. Density-dependent quiescence also abolishes HiNF-D binding activity. Downregulation of transcription from the H4 gene occurs concomitant with the loss of the HiNF-D/Site II interaction, further suggesting a functional relationship between Site II occupancy and the capacity for transcription. Serum stimulation of quiescent preconfluent cells results in an increase in HiNF-D binding activity as the cells are resuming DNA synthesis and H4 histone gene transcription. Density-inhibited quiescent cells respond to serum stimulation with only a minimal increase in the HiNF-D binding activity, 30% of maximal levels. However, H4 histone gene transcription is stimulated to a level equal to that detected in extracts of the sparsely populated serum-stimulated cultures. These results suggest that there is a threshold level of HiNF-D binding activity necessary for the activation of H4 histone gene transcription.(ABSTRACT TRUNCATED AT 250 WORDS)
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Citation: Biochemistry. 1992 Mar 17;31(10):2812-8.
Wright, Kenneth Lynn; Dell'Orco, Robert T.; Van Wijnen, Andre J.; Stein, Janet L.; and Stein, Gary S., "Multiple mechanisms regulate the proliferation-specific histone gene transcription factor HiNF-D in normal human diploid fibroblasts" (1992). GSBS Student Publications. 948.