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Transmissibility of mouse AApoAII amyloid fibrils: inactivation by physical and chemical methods
Huanyu Zhang1, Jinko Sawashita, Xiaoying Fu
1Department of Aging Biology, Institute on Aging and Adaptation, Shinshu University Graduate School of Medicine, Asahi 3-1-1, Matsumoto 390-8621, Japan.
Abstract:
AApoAII amyloid fibrils have exhibited prion-like transmissibility in mouse senile amyloidosis. We have demonstrated that AApoAII is extremely active and can induce amyloidosis following doses less than 1 pg. We tested physical and chemical methods to disrupt AApoAII fibrils in vitro as determined by thioflavin T binding and electron microscopy (EM) as well as inactivating the transmissibility of AApoAII fibrils in vivo. Complete disruption of AApoAII fibrils was achieved by treatment with formic acid, 6 M guanidine hydrochloride, and autoclaving in an alkaline solution. Injection of these disrupted AApoAII fibrils did not induce amyloidosis in mice. Disaggregation with 6 M urea, autoclaving, and alkaline solution was incomplete, and injection of these AApoAII fibrils induced mild amyloidosis. Treatment with formalin, delipidation, freeze-thaw, and RNase did not have any major effect. A distinct correlation was obtained between the amounts of amyloid fibrils and the transmissibility of amyloid fibrils, thereby indicating the essential role of fibril conformation for transmission of amyloidosis. We also studied the inactivation of AApoAII fibrils by several organic compounds in vitro and in vivo. AApoAII amyloidosis provides a valuable system for studying factors that may prevent transmission of amyloid disease as well as potential novel therapies.
Insights
AApoAII amyloid fibrils transmit amyloidosis in mice. Disrupting these fibrils with formic acid, guanidine hydrochloride, or autoclaving prevented transmission, highlighting the role of fibril conformation in disease spread.
Area of Science:
- Biochemistry
- Neuroscience
- Pathology
Background:
- AApoAII amyloid fibrils exhibit prion-like transmissibility in mouse senile amyloidosis.
- These fibrils are highly active, inducing amyloidosis at doses below 1 pg.
Purpose of the Study:
- To investigate physical and chemical methods for disrupting AApoAII fibrils in vitro.
- To inactivate the transmissibility of AApoAII fibrils in vivo.
- To correlate amyloid fibril amounts with transmissibility and understand the role of fibril conformation.
Main Methods:
- In vitro disruption assays using thioflavin T binding and electron microscopy (EM).
- In vivo transmissibility studies in mice following injection of treated fibrils.
- Testing various chemical agents (formic acid, guanidine hydrochloride, urea, formalin) and physical methods (autoclaving, freeze-thaw, delipidation).
Main Results:
- Complete fibril disruption and inactivation of transmissibility were achieved with formic acid, 6 M guanidine hydrochloride, and autoclaving in alkaline solution.
- Incomplete disruption and mild amyloidosis induction occurred with 6 M urea, autoclaving, and alkaline solution alone.
- Formalin, delipidation, freeze-thaw, and RNase treatments showed no significant effect on fibril transmissibility.
- A strong correlation was observed between amyloid fibril load and transmissibility, emphasizing fibril conformation's importance.
Conclusions:
- Fibril conformation is critical for the transmission of amyloidosis.
- Effective disruption methods (formic acid, guanidine HCl, alkaline autoclaving) can inactivate AApoAII amyloid fibrils.
- AApoAII amyloidosis serves as a model for studying amyloid disease transmission and developing therapeutic strategies.
