Internalized Amyloid-β (1-42) Peptide Inhibits the Store-Operated Calcium Entry in HT-22 Cells.

Area of Science:

• Neuroscience
• Cell Biology
• Biochemistry

Background:

• Calcium signaling dysregulation is central to Alzheimer's disease (AD) pathogenesis.
• Amyloid-beta (Aβ) oligomers are cytotoxic and implicated in AD.
• Store-operated calcium entry (SOCE) is impaired in AD, affecting neuronal stability.

Purpose of the Study:

• To investigate the interaction between Aβ(1-42) oligomers and STIM1, a calcium-binding protein.
• To determine if Aβ(1-42) affects SOCE function in neuronal cells.
• To elucidate the early molecular mechanisms of Aβ-induced cellular dysfunction in AD.

Main Methods:

• Incubation of HT-22 cells with Aβ(1-42) oligomers.
• Quantification of Aβ(1-42) internalization and colocalization with endoplasmic reticulum (ER).
• Co-immunoprecipitation to assess STIM1-Aβ interaction.
• Förster resonance energy transfer (FRET) to measure binding affinity.
• Monitoring of SOCE and cytosolic calcium homeostasis.

Main Results:

• Internalized Aβ(1-42) oligomers colocalize with ER and bind to STIM1.
• STIM1 directly binds Aβ(1-42) oligomers near its calmodulin-binding site.
• Aβ(1-42) exposure dysregulates SOCE in HT-22 cells prior to significant cytosolic calcium changes.
• STIM1 inhibition and ER calcium leak contribute to Aβ-induced SOCE disruption.

Conclusions:

• STIM1 is a novel direct target of Aβ(1-42) oligomers.
• Aβ(1-42)-induced inhibition of STIM1 disrupts SOCE, representing an early pathogenic event in AD.
• This mechanism contributes to neuronal calcium dyshomeostasis and potential downstream AD pathology.