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Retardation of Abeta fibril formation by phospholipid vesicles depends on membrane phase behavior

Erik Hellstrand1, Emma Sparr, Sara Linse

  • 1Department of Biophysical Chemistry, Lund University, Lund, Sweden. erik.hellstrand@bpc.lu.se

Biophysical Journal
|May 21, 2010
PubMed

Insights

Lipid membranes significantly slow amyloid beta peptide fibril formation in Alzheimer's disease research. Membrane phase behavior, particularly solid gel phases, greatly influences this retardation effect.

Area of Science:

  • Biochemistry
  • Neuroscience
  • Materials Science

Background:

  • Amyloid diseases, including Alzheimer's, involve protein misfolding and fibril formation.
  • Membrane interactions are increasingly implicated in both in vivo fibril formation and toxicity mechanisms of amyloid diseases.
  • Alzheimer's disease is characterized by the aggregation of amyloid beta peptide (Abeta).

Purpose of the Study:

  • To investigate the influence of lipid membranes on the aggregation kinetics of Alzheimer's disease-related amyloid beta peptide (Abeta).
  • To determine how different membrane phase behaviors affect Abeta fibril formation.
  • To explore the role of membrane charge in modulating Abeta aggregation.

Main Methods:

  • Utilized recombinant Abeta(M1-40) and Abeta(M1-42) produced in E. coli for large-scale kinetics assays.
  • Monitored amyloid formation using thioflavin T fluorescence at near-physiological peptide concentrations (down to 380 nM).
  • Introduced lipid membranes as large and small unilamellar vesicles to study their effect on aggregation.

Main Results:

  • Lipid vesicles increased the aggregation lagtime of Abeta across all conditions studied.
  • The phase behavior of the lipid membrane significantly impacted Abeta aggregation kinetics.
  • Dipalmitoylphosphatidylcholine bilayers in a solid gel phase exhibited the greatest retardation of Abeta fibril formation.
  • Membrane-induced retardation saturated and occurred when vesicles were added up to the nucleation point.
  • Increasing negative charge in the membrane did not significantly alter the lagtime.

Conclusions:

  • Lipid membranes play a crucial role in modulating amyloid beta peptide aggregation.
  • The physical state (phase behavior) of the membrane is a key determinant of its influence on fibril formation.
  • Solid gel phase lipid bilayers effectively inhibit Abeta fibril formation, suggesting potential therapeutic strategies targeting membrane interactions.

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