A natural product inhibits the initiation of α-synuclein aggregation and suppresses its toxicity

Michele Perni; Céline Galvagnion; Alexander Maltsev; Georg Meisl; Martin B. D. Müller; Pavan K. Challa; Julius B. Kirkegaard; Patrick Flagmeier; Samuel I. A. Cohen; Roberta Cascella; Serene W. Chen; Ryan Limbocker; Pietro Sormanni; Gabriella T. Heller; Francesco A. Aprile; Nunilo Cremades; Cristina Cecchi; Fabrizio Chiti; Ellen A. A. Nollen; Tuomas P. J. Knowles; Michele Vendruscolo; Adriaan Bax; Michael Zasloff; Christopher M. Dobson

doi:10.1073/pnas.1610586114

Edited by Gregory A. Petsko, Weill Cornell Medical College, New York, NY, and approved December 5, 2016 (received for review June 29, 2016)

Significance

Parkinson’s disease is characterized by the presence in brain tissues of aberrant aggregates primarily formed by the protein α-synuclein. It has been difficult, however, to identify compounds capable of preventing the formation of such deposits because of the complexity of the aggregation process of α-synuclein. By exploiting recently developed highly quantitative in vitro assays, we identify a compound, squalamine, that blocks α-synuclein aggregation, and characterize its mode of action. Our results show that squalamine, by competing with α-synuclein for binding lipid membranes, specifically inhibits the initiation of the aggregation process of α-synuclein and abolishes the toxicity of α-synuclein oligomers in neuronal cells and in an animal model of Parkinson’s disease.

Abstract

The self-assembly of α-synuclein is closely associated with Parkinson’s disease and related syndromes. We show that squalamine, a natural product with known anticancer and antiviral activity, dramatically affects α-synuclein aggregation in vitro and in vivo. We elucidate the mechanism of action of squalamine by investigating its interaction with lipid vesicles, which are known to stimulate nucleation, and find that this compound displaces α-synuclein from the surfaces of such vesicles, thereby blocking the first steps in its aggregation process. We also show that squalamine almost completely suppresses the toxicity of α-synuclein oligomers in human neuroblastoma cells by inhibiting their interactions with lipid membranes. We further examine the effects of squalamine in a Caenorhabditis elegans strain overexpressing α-synuclein, observing a dramatic reduction of α-synuclein aggregation and an almost complete elimination of muscle paralysis. These findings suggest that squalamine could be a means of therapeutic intervention in Parkinson’s disease and related conditions.

Footnotes

↵¹Present address: German Center for Neurodegenerative Diseases (DZNE), 53127 Bonn, Germany, and Institute of Physical Biology, Heinrich Heine Universität, Universitätsstr.1, 40225 Duesseldorf, Germany.
↵²To whom correspondence may be addressed. Email: mv245{at}cam.ac.uk, bax{at}nih.gov, maz5{at}georgetown.edu, or cmd44{at}cam.ac.uk.

Author contributions: M.P., E.A.A.N., T.P.J.K., M.V., A.B., M.Z., and C.M.D. designed research; M.P., C.G., A.M., G.M., M.B.D.M., P.K.C., J.B.K., P.F., R.C., R.L., P.S., G.T.H., F.A.A., C.C., F.C., T.P.J.K., A.B., and M.Z. performed research; P.K.C., S.W.C., N.C., and E.A.A.N. contributed new reagents/analytic tools; M.P., C.G., A.M., G.M., P.K.C., J.B.K., P.F., S.I.A.C., R.C., R.L., P.S., C.C., F.C., E.A.A.N., T.P.J.K., A.B., M.Z., and C.M.D. analyzed data; and M.P., T.P.J.K., M.V., A.B., M.Z., and C.M.D. wrote the paper.
Conflict of interest statement: M.Z. is the inventor on a patent application that has been filed related to the compound described in this paper. The other authors declare no conflict of interest.
This article is a PNAS Direct Submission.
See Commentary on page 1223.
This article contains supporting information online at www.pnas.org/lookup/suppl/doi:10.1073/pnas.1610586114/-/DCSupplemental.

Freely available online through the PNAS open access option.

View Full Text