The growth-dependent expression of the adenine nucleotide translocase-2 (ANT2) gene is regulated at the level of transcription and is a marker of cell proliferation

The adenine nucleotide translocator-2 (ANTS) gene is expressed in growth-activated cells together with the early-immediate genes. We have studied the mechanism of ANTS expression during the serum-induced transition from G0 to G1 and during reentry into G0 as cells approach confluence. Actinomycin D completely blocked ANTS expression of serum-induced quiescent NIH3T3. In addition, no serum-dependent changes were observed in the stability of ANT2 transcripts in cells activated by serum or during the breakdown of transcripts caused by serum removal and reentry into G0. Thus, all changes in ANTS transcript levels appear to be regulated predominantly at the level of transcription. Using cells permanently transfected with deletion constructs of the ANTE promoter, we identified a suppressor region that is responsible for decreased expression of ANTS in cells leaving the growth cycle at confluence. Thus, ANTE is expressed during the proliferation state via a mechanism that most probably includes transcription repression/derepression. (C) 1999 Academic Press.