. A soluble α-synuclein construct forms a dynamic tetramer. Proc Natl Acad Sci U S A. 2011 Oct 25;108(43):17797-802. Epub 2011 Oct 17 PubMed.

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  1. Reply to comments by Eliezer Masliah and Hilal Lashuel
    Comments by Dr. Lashuel within the ARF news story and the added comment by Dr. Masliah do not fully reflect what we actually published in the paper. First, Dr. Lashuel suggested that one should run the denatured recombinant protein side by side with cell extracts. That is just what we did, and showed in Supp. Fig. S5 A and B. These two figures demonstrate the distinct migration of the cell-derived α-synuclein versus both recombinant α-synuclein and denatured cell-derived α-synuclein. Also, Dr. Lashuel chooses not to mention the higher percentages of cellular α-synuclein we observed to migrate as tetramers versus monomers upon crosslinking of intact cells other than red blood cells (RBC). In any event, such in-vivo crosslinking is not fully efficient, as the news story points out.

    Dr. Masliah appears to overlook the considerable data on α-synuclein in cell types other than RBC in our paper, most importantly, the native (α-helically folded) α-synuclein purified from human neuroblastoma cells, which was sized by scanning transmission electron microscopy (STEM) at ~55,000 Daltons (Fig. S7), a value indistinguishable from the STEM sizing of the RBC α-synuclein, addressing what he is inquiring about. There are several additional data about α-synuclein from cells other than RBC in the article, for example, in Fig. 1, Fig. S5A, Fig. S6, Fig. S8, and Fig. S9. In addition, even though much of our work was done on the abundant, native α-synuclein found endogenously in fresh RBC, the resulting findings should still have more relevance to other human cell types (including neurons) than the bacterially expressed protein extensively used heretofore. Indeed, we report a post-translational modification (N-acetylation) that we documented in RBC by mass spectrometry (Fig. S4) that was not shown to exist on α-synuclein previously, and that is not present on bacterially expressed α-synuclein.

    Finally, it seems unlikely to us that "several labs, both academic and private, have tried to reproduce these findings since they were first presented in public, according to some researchers" as the data were only presented publicly a few months before the article appeared, and the multiple biochemical and biophysical approaches we used to purify, characterize, and size the native cellular form of α-synuclein over more than two years will understandably take time and effort to reproduce. To this end, we have provided very extensive details about our methods to readers via the nature Protocol Exchange website, as we mentioned in the paper (see Methods and Nature Protocol Exchange), and we are actively communicating with other labs (including Dr. Lashuel's) to assist them in any way we can to reproduce the findings.

    View all comments by Dennis Selkoe

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