Uncovering the Early Events Associated with Oligomeric Aβ-Induced Src Activation

Area of Science:

• Neuroscience
• Biochemistry
• Cell Biology

Background:

• Soluble amyloid-beta oligomers (AβO) are implicated in early Alzheimer's disease (AD) pathogenesis.
• AβO are known to elevate intracellular calcium and impair mitochondrial function via N-methyl-D-aspartate receptors (NMDAR).
• Src kinase interacts with NMDAR, but its role in early AβO-induced neurotoxicity is unclear.

Purpose of the Study:

• To investigate the influence of brief oligomeric Aβ_1-42 exposure on Src kinase activation.
• To elucidate the mechanisms linking Src activation to mitochondrial dysfunction and redox changes in hippocampal neurons.

Main Methods:

• Primary rat hippocampal neurons were briefly exposed to oligomeric Aβ_1-42.
• Analyzed Src activation, NMDAR activity, intracellular calcium levels, and reactive oxygen species (ROS) generation (cytosolic and mitochondrial).
• Assessed mitochondrial morphology and effects of Src inhibition.

Main Results:

• Brief AβO exposure induced hydrogen peroxide (H₂O₂)-dependent Src activation.
• Observed NMDAR activation, increased intracellular calcium, and elevated cytosolic and mitochondrial H₂O₂ levels.
• Noted mild mitochondrial fragmentation, which was prevented by Src inhibition, indicating a feedforward loop.

Conclusions:

• Src kinase activation plays a key role in early AβO-induced neurodysfunction.
• AβO triggers Src activation, leading to synaptic homeostasis loss via cytosolic and mitochondrial ROS generation.
• Modulating Src activity may offer a protective strategy for mitochondria and hippocampal glutamatergic synapses in AD.