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PI3K-ERK1/2 activation contributes to extracellular H2O2 generation in amyloid β toxicity

Jong Seong Ha1, Hye Yeong Sung, Heon M Lim

  • 1Aging Research Center, Korea Research Institute of Bioscience and Biotechnology (KRIBB), Daejeon 305-806, Republic of Korea.

Neuroscience Letters
|August 29, 2012
PubMed

Insights

Amyloid β (Aβ) triggers neuronal death by increasing hydrogen peroxide (H2O2) and superoxide generation. This study identifies specific NADPH oxidase isotypes and signaling pathways involved in Aβ-induced oxidative stress, crucial for Alzheimer's disease research.

Area of Science:

  • Neuroscience
  • Biochemistry
  • Cell Biology

Background:

  • Amyloid β (Aβ) peptide is implicated in neuronal death via oxidative stress.
  • The specific NADPH oxidase isotypes and signaling pathways (PI3K, ERK1/2) involved in Aβ-induced extracellular H2O2 generation remain unclear.
  • Understanding these mechanisms is vital for Alzheimer's disease (AD) pathogenesis.

Purpose of the Study:

  • To investigate the role of specific NADPH oxidase isotypes in Aβ-induced H2O2 and superoxide generation.
  • To elucidate the involvement of phosphoinositide 3-kinase (PI3K) and extracellular signal-regulated kinase (ERK) 1/2 in Aβ-mediated oxidative stress.
  • To determine the contribution of Aβ-induced H2O2 to neuronal cytotoxicity.

Main Methods:

  • Utilized Aβ1-42 to induce H2O2 and superoxide generation in neuronal models.
  • Employed Nox2- and Nox4-specific siRNAs to assess NADPH oxidase isotype roles.
  • Administered PI3K (LY294002) and ERK1/2 (U0126) inhibitors to evaluate signaling pathway involvement.
  • Assessed cytotoxicity and H2O2 levels following Aβ1-42 and glutamate co-treatment.

Main Results:

  • Aβ1-42 induced concentration-dependent extracellular H2O2 generation and cytotoxicity.
  • Nox2 and Nox4 siRNAs significantly suppressed Aβ-induced H2O2 and superoxide production.
  • PI3K and ERK1/2 inhibition reduced H2O2 generation, with PI3K activation preceding ERK1/2 phosphorylation.
  • Combined Aβ1-42 and glutamate treatment exacerbated H2O2 generation and cytotoxicity.

Conclusions:

  • Aβ1-42 enhances neuronal vulnerability to oxidative injury in Alzheimer's disease by increasing extracellular H2O2 generation.
  • Nox2 and Nox4 are key NADPH oxidase isotypes mediating Aβ-induced oxidative stress.
  • The PI3K/ERK1/2 signaling pathway plays a critical role in regulating Aβ-induced H2O2 production and subsequent neuronal damage.

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