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p21 is required for atRA-mediated growth inhibition of MEPM cells, which involves RAR

Zengli Yu1, Wenjie Li, Quanjun Lu

  • 1Department of Nutrition and Food Hygiene, College of Public Health, Zhengzhou University, Zhengzhou 450001, China. zly@zzu.edu.cn

Journal of Cellular Biochemistry
|April 22, 2008
PubMed

Insights

All-trans retinoic acid (atRA) inhibits mouse embryonic palatal mesenchymal cell growth by increasing p21 levels, causing cell cycle arrest. This study identifies p21 as a key mediator in atRA

Area of Science:

  • Developmental Biology
  • Cell Biology
  • Molecular Biology

Background:

  • All-trans retinoic acid (atRA), a vitamin A metabolite, is crucial for embryonic development.
  • Tight control of atRA's spatial and temporal distribution is essential.
  • Excessive atRA can cause growth inhibition and p21 accumulation in MEPM cells.

Purpose of the Study:

  • To identify the mediator of all-trans retinoic acid-induced growth inhibition in mouse embryonic palatal mesenchymal cells.
  • To elucidate the role of p21 in atRA-mediated cellular responses.
  • To investigate the involvement of RAR in the atRA signaling pathway.

Main Methods:

  • Cell cycle analysis (flow cytometry) to assess G1 arrest and DNA fragmentation.
  • Western blotting to evaluate protein levels (p21, cyclin D1) and Rb phosphorylation.
  • Luciferase reporter assays to measure p21 and RARE promoter activity.
  • siRNA-mediated gene silencing to assess the necessity of p21 and RAR.
  • Chromatin immunoprecipitation (ChIP) to confirm RAR binding to the p21 promoter.

Main Results:

  • atRA induced G1 cell cycle arrest and DNA fragmentation in MEPM cells.
  • atRA treatment increased p21 protein levels and decreased cyclin D1 and Rb phosphorylation.
  • p21 is required for atRA-induced growth inhibition, as confirmed by siRNA knockdown.
  • RAR is involved in atRA-induced p21 expression, with RAR binding to the p21 promoter.

Conclusions:

  • p21 is the primary mediator of all-trans retinoic acid-induced growth inhibition in mouse embryonic palatal mesenchymal cells.
  • RAR signaling plays a significant role in regulating p21 expression and mediating the cellular effects of atRA.
  • These findings highlight a critical molecular mechanism governing embryonic development and cellular growth control by vitamin A metabolites.

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