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Downregulation of transcription factor, Sp1, during cellular senescence

Ji-Eun Oh1, Jung-A Han, Eun Seong Hwang

  • 1Department of Life Science, University of Seoul, Dongdaemungu, Jeonnongdong 90, Seoul 130-743, Republic of Korea.

Biochemical and Biophysical Research Communications
|December 13, 2006
PubMed

Insights

The Sp1 transcription factor decreases during cellular aging and with DNA damage. This reduction is due to accelerated proteasomal degradation, potentially explaining decreased gene transcription in aging cells.

Area of Science:

  • Molecular Biology
  • Cellular Senescence
  • Transcription Factor Regulation

Background:

  • Cellular aging and senescence are associated with global changes in gene expression.
  • The Sp1 transcription factor plays a crucial role in regulating gene transcription.
  • The regulatory mechanisms of Sp1 during aging and DNA damage are not fully understood.

Purpose of the Study:

  • To investigate the changes in Sp1 protein levels during replicative aging and induced cellular senescence.
  • To determine the role of DNA damage signaling pathways in regulating Sp1 levels.
  • To elucidate the mechanism responsible for Sp1 downregulation.

Main Methods:

  • Analysis of Sp1 protein levels in normal human fibroblasts undergoing replicative aging.
  • Assessment of Sp1 protein and activity in MCF-7 cells induced into senescence.
  • Treatment of cells with DNA damaging agents (actinomycin D, H2O2) and proteasome inhibitor (ALLN).
  • Inhibition of ATM/ATR kinases to study DNA damage signaling involvement.

Main Results:

  • Sp1 protein levels significantly decrease during replicative aging of human fibroblasts.
  • Sp1 protein levels and activity rapidly decline in senescent MCF-7 cells.
  • Progressive Sp1 downregulation was observed in cells treated with DNA damaging chemicals.
  • Inhibition of ATM/ATR kinases prevented Sp1 downregulation, indicating involvement of DNA damage signaling.
  • Sp1 decrease is attributed to accelerated proteasomal degradation, as shown by ALLN treatment.

Conclusions:

  • The Sp1 transcription factor is downregulated during cellular aging and senescence.
  • DNA damage signaling pathways, involving ATM/ATR kinases, regulate Sp1 levels.
  • Accelerated proteasomal degradation is the primary mechanism for Sp1 loss in aging cells.
  • Decreased Sp1 levels may contribute to the global reduction in gene transcription observed in aging cells and tissues.

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