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Nrf2-induced antiapoptotic Bcl-xL protein enhances cell survival and drug resistance

Suryakant K Niture1, Anil K Jaiswal

  • 1Department of Pharmacology, University of Maryland School of Medicine, Baltimore, MD 21201, USA.

Free Radical Biology & Medicine
|January 1, 2013
PubMed

Insights

Nuclear factor Nrf2 regulates Bcl-xL protein expression, impacting apoptosis and cell survival. This study reveals Nrf2

Area of Science:

  • Molecular Biology
  • Cellular Biology
  • Biochemistry

Background:

  • Nuclear factor erythroid 2-related factor 2 (Nrf2) is a transcription factor that regulates antioxidant and cytoprotective genes.
  • Bcl-xL is an antiapoptotic protein involved in cell survival and resistance to programmed cell death.
  • The precise regulatory mechanisms of Bcl-xL expression by Nrf2 are not fully understood.

Purpose of the Study:

  • To investigate the role of Nrf2 in the regulation of Bcl-xL protein expression.
  • To determine the effect of Nrf2-mediated Bcl-xL expression on cellular apoptosis and cancer cell survival.

Main Methods:

  • Reporter gene assays and promoter mutagenesis to identify the Nrf2 binding site (ARE) in the Bcl-xL promoter.
  • Chromatin immunoprecipitation (ChIP) assays to confirm Nrf2 binding to the Bcl-xL promoter.
  • Short interfering RNA (siRNA) and overexpression studies to manipulate Nrf2 and Bcl-xL levels.
  • Analysis of apoptosis markers (Bax, caspase 3/7 activity) and cell viability assays.

Main Results:

  • An antioxidant-response element (ARE) was identified in the Bcl-xL promoter that binds Nrf2, leading to increased Bcl-xL expression.
  • Nrf2 directly regulates Bcl-xL gene expression, influencing its protein levels.
  • Nrf2-induced Bcl-xL expression downregulates Bax, reduces caspase 3/7 activity, and promotes cell survival.
  • Inhibition of Nrf2 and Bcl-xL increases cancer cell susceptibility to etoposide-induced death.
  • Dysfunctional Nrf2 inhibitor (INrf2) in lung cancer cells leads to elevated Bcl-xL and enhanced cell survival.

Conclusions:

  • Nrf2 is a key regulator of Bcl-xL expression, impacting apoptotic pathways.
  • Nrf2-mediated Bcl-xL expression contributes to cellular protection, cancer cell survival, and potentially drug resistance.
  • These findings elucidate a novel mechanism of Nrf2 in controlling cell death and survival, with implications for cancer therapy.

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