Hydrogen peroxide attenuates the prosurvival signaling of insulin-like growth factor-1 through two pathways

Area of Science:

• Neuroscience
• Cell Biology
• Biochemistry

Background:

• Oxidative stress is known to induce cell death through various signaling pathways.
• The impact of oxidative stress on prosurvival factors like insulin-like growth factor-1 (IGF-1) signaling remains less understood.
• IGF-1 signaling plays a crucial role in cell survival and neuroprotection.

Purpose of the Study:

• To investigate the mechanism by which hydrogen peroxide (H₂O₂) attenuates IGF-1 prosurvival signaling.
• To elucidate the specific pathways involved in the disruption of IGF-1 signaling by oxidative stress.
• To determine the role of glutamate receptors in mediating the effects of H₂O₂ on IGF-1 signaling.

Main Methods:

• Cell viability was assessed using the MTT assay.
• Western blotting was employed to determine the phosphorylation status of IGF-1 receptors, Akt, and ERK.
• Cells were pretreated with Trolox (antioxidant) or various glutamate receptor antagonists (MK-801, DNQX, LY341495, CPCCOEt) before exposure to H₂O₂ and IGF-1 stimulation.

Main Results:

• H₂O₂ abolished the neuroprotective effect of IGF-1 and attenuated the phosphorylation of IGF-1 receptors, Akt, and ERK.
• Akt phosphorylation was more sensitive to H₂O₂ insult than IGF-1 receptor phosphorylation.
• N-methyl-D-aspartate (NMDA) receptor antagonist MK-801 increased IGF-1 receptor and Akt phosphorylation, enhancing cell survival, while other glutamate receptor antagonists had no significant effect.
• Trolox increased cell viability and Akt phosphorylation but did not restore IGF-1 signaling.

Conclusions:

• H₂O₂ impairs IGF-1 prosurvival signaling through two distinct pathways.
• One pathway involves the disruption of IGF-1 receptor autophosphorylation mediated by NMDA receptors.
• The second pathway involves the direct dephosphorylation of Akt by H₂O₂.