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Published on: May 22, 2018
The Interplay Between Cholesterol and Amyloid-β on HT22 Cell Viability, Morphology, and Receptor Tyrosine Kinase
Morgan J Robinson1,2, Sean Newbury1, Kartar Singh1
1School of Pharmacy, University of Waterloo, Waterloo, ON, Canada.
Background:
There is a lack of understanding in the molecular and cellular mechanisms of Alzheimer's disease that has hindered progress on therapeutic development. The focus has been on targeting toxic amyloid-β (Aβ) pathology, but these therapeutics have generally failed in clinical trials. Aβ is an aggregation-prone protein that has been shown to disrupt cell membrane structure in molecular biophysics studies and interfere with membrane receptor signaling in cell and animal studies. Whether the lipid membrane or specific receptors are the primary target of attack has not been determined.
Objective:
This work elucidates some of the interplay between membrane cholesterol and Aβ42 on HT22 neuronal cell viability, morphology, and platelet-derived growth factor (PDGF) signaling pathways.
Methods:
The effects of cholesterol depletion by methyl-β-cyclodextrin followed by treatment with Aβ and/or PDGF-AA were assessed by MTT cell viability assays, western blot, optical and AFM microscopy.
Results:
Cell viability studies show that cholesterol depletion was mildly protective against Aβ toxicity. Together cholesterol reduction and Aβ42 treatment compounded the disruption of the PDGFα receptor activation. Phase contrast optical microscopy and live cell atomic force microscopy imaging revealed that cytotoxic levels of Aβ42 caused morphological changes including cell membrane damage, cytoskeletal disruption, and impaired cell adhesion; cell damage was ameliorated by cellular cholesterol depletion.
Conclusions:
Cholesterol depletion impacted the effects of Aβ42 on HT22 cell viability, morphology, and receptor tyrosine kinase signaling.
Insights
Cholesterol depletion offers mild protection against amyloid-beta (Aβ) toxicity in neuronal cells. Reducing cholesterol impacts Aβ42
Area of Science:
- Neuroscience
- Molecular Biology
- Biophysics
Background:
- Alzheimer's disease (AD) therapeutics targeting amyloid-beta (Aβ) have largely failed due to a poor understanding of its molecular mechanisms.
- Aβ is known to disrupt cell membranes and receptor signaling, but the primary target remains unclear.
Purpose of the Study:
- To investigate the interplay between membrane cholesterol and Aβ42 in neuronal cells.
- To determine the effects of cholesterol modulation on cell viability, morphology, and signaling pathways.
Main Methods:
- Utilized methyl-β-cyclodextrin for cholesterol depletion in HT22 neuronal cells.
- Assessed Aβ42 and PDGF-AA treatments using MTT assays, western blot, and atomic force microscopy (AFM).
Main Results:
- Cholesterol depletion provided mild protection against Aβ toxicity and mitigated Aβ42-induced cell damage.
- Combined cholesterol reduction and Aβ42 treatment exacerbated disruption of PDGFα receptor activation.
- Aβ42 caused morphological changes, including membrane damage and cytoskeletal disruption, which were ameliorated by cholesterol depletion.
Conclusions:
- Cholesterol levels significantly influence the impact of Aβ42 on neuronal cell viability and morphology.
- Cholesterol depletion affects Aβ42-induced changes in receptor tyrosine kinase signaling pathways.
