Bistability explains threshold phenomena in protein aggregation both in vitro and in vivo

Theodore R. Rieger, Richard I. Morimoto, Vassily Hatzimanikatis*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

22 Scopus citations


Neurodegenerative disease can originate from the misfolding and aggregation of proteins, such as Amyloid-β, SOD1, or Huntingtin. Fortunately, all cells possess protein quality control machinery that sequesters misfolded proteins, either refolding or degrading them, before they can self-associate into proteotoxic oligomers and aggregates. This activity is largely performed by the stress response chaperones (i.e., Hsp70). However, the expression level of molecular chaperones varies widely among cell types. To understand the potential consequence of this variation, we studied the process of protein aggregation in the presence of molecular chaperones using mathematical modeling. We demonstrate that protein aggregation, in the presence of molecular chaperones, is a bistable process. Bistability in protein aggregation offers an explanation for threshold transitions to high aggregate concentration, which are observed both in vitro and in vivo. Additionally, we show that slight variations in chaperone concentration, due to natural fluctuations, have important consequences in a bistable system for the onset of protein aggregation. Therefore, our results offer a possible theoretical explanation for neuronal vulnerability observed in vivo and the onset of neurodegenerative phenotypes in neurons lacking an effective heat-shock response.

Original languageEnglish (US)
Pages (from-to)886-895
Number of pages10
JournalBiophysical Journal
Issue number3
StatePublished - Feb 2006

ASJC Scopus subject areas

  • Biophysics


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