Laser-induced Propagation and Destruction of Amyloid β Fibrils

Yuji Goto,Kazumasa Sakurai,Ryoichi Kuboi,Daisaku Ozawa,Toshinori Shimanouchi,Hiroki Kuyama,Hironobu Naiki,Hisashi Yagi,Toru Kawakami,Osamu Nishimura

doi:10.1074/jbc.m109.076505

Yuji Goto, Kazumasa Sakurai + Show 8 more

Open Access

https://doi.org/10.1074/jbc.m109.076505

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Abstract

The amyloid deposition of amyloid beta (Abeta) peptides is a critical pathological event in Alzheimer disease (AD). Preventing the formation of amyloid deposits and removing preformed fibrils in tissues are important therapeutic strategies against AD. Previously, we reported the destruction of amyloid fibrils of beta(2)-microglobulin K3 fragments by laser irradiation coupled with the binding of amyloid-specific thioflavin T. Here, we studied the effects of a laser beam on Abeta fibrils. As was the case for K3 fibrils, extensive irradiation destroyed the preformed Abeta fibrils. However, irradiation during spontaneous fibril formation resulted in only the partial destruction of growing fibrils and a subsequent explosive propagation of fibrils. The explosive propagation was caused by an increase in the number of active ends due to breakage. The results not only reveal a case of fragmentation-induced propagation of fibrils but also provide insights into therapeutic strategies for AD.

Highlights

The deposition of amyloid fibrils in extra- and intracellular spaces is associated with various amyloidoses, including Alzheimer disease (AD),2 Parkinson, and Huntington diseases and dialysis-related amyloidosis (1–3)
We suggested that active oxygen generated by the excitation of thioflavin T (ThT) played a critical role in the destruction of the fibrils along with various chemical modifications
Propagation of A␤(1– 40) Fibrils—We carried out real-time observations by total internal reflection fluorescence microscopy (TIRFM) of the spontaneous fibril formation of A␤(1– 40) at 500 ␮M. A␤(1– 40) (50 ␮M) and pH 7.5 at 37 °C in the presence of 5 ␮M ThT (Fig. 1)

Summary

Introduction

The deposition of amyloid fibrils in extra- and intracellular spaces is associated with various amyloidoses, including Alzheimer disease (AD), Parkinson, and Huntington diseases and dialysis-related amyloidosis (1–3). In the case of yeast Sup protein, the chaperon Hsp40/70 system disaggregates fibrillar Sup into oligomeric species for transmission from mother to daughter cells (15, 16) Such evidence suggests that the propagation of fibrils is a more dynamic process than that assumed on the basis of a simple process of nucleation and growth (13). To directly observe the growth of fibrils, we developed a unique method combining total internal reflection fluorescence microscopy (TIRFM) with thioflavin T (ThT), an amyloid-specific fluorescence dye (6, 8, 9, 17, 18). This approach can provide information about the formation of individual fibrils in real time. Considering that self-propagation is intrinsic to amyloid fibrils, a dependence with an optimum may be common to various structural perturbants of amyloid fibrils giving important insights into therapeutic strategies for preventing amyloidosis

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