Piperine Derivatives Enhance Fusion and Axonal Transport of Mitochondria by Activating Mitofusins

Round 1

Reviewer 1 Report

 

The authors identify that piperine and its derivatives can enhance mitochondria fusion and motility. These findings are interesting, as they may lead to development of new clinical drugs to regulate mitochondria dynamics for therapy.

However, based on findings from the current study the effects of piperine and its derivatives on promotion of mitochondria fusion and motility is similar to or poorer than that of MIM111, a previous identified mitofusion activator. Therefore the novelty and significance of the current study will be compromised.

Furthermore the authors only study the effects of compounds on cells lack of mfns. However how these compounds will influence mitochondria fusion and motility in the presence of wild type mfn1 and mfn2 are not studied. If these compounds have no significant influence on mitochondria fusion and motility in the presence of wild type mfn1 and mfn2, then the potential scientific impacts of findings will be limited. Therefore piperine and its derivatives effects on mitochodria motility and fusions in the presence of wild type mfn2 and mfn1 should be investigated.  

minor defects:

1, a positive control group of cells transfected with wild type mfn1 or mfn2 to significantly increase mitofusion is suggested to be added.

2, the curve of fusogenic response in Figure 2B and Figure 5B is not accurate. The fusogenic response begins to drop from -6 to -5 Log10C. However, the curves on the figure show platform extension of lines. This should be corrected.  

Author Response

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Reviewer 2 Report

This study evaluated the effects of piperine on mitofusin-mediated mitochondrial elongation by demonstrating its function as a potent activator of mitofusin at low nanomolar concentrations; various piperine derivatives have been synthesized and characterized, capable of improving the fusion and axonal transport of mitochondria, representing a new class of mitofusin activators.

The research design is appropriate, the methodological analyses are suitable and adequately described, the data are clearly presented and the conclusions are sustained by the results.

Overall, I have no criticism about the manuscript which in my opinion can be accepted for publication in its current form.

Author Response

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Reviewer 3 Report

In the paper “Piperine derivatives enhance fusion and axonal transport of mitochondria by activating mitofusins” the authors provide evidence that mitofusin activation is a new mechanism by which piperine exerts his action. They synthesized piperine analogs with structural features expected to optimize mitofusin activation and defined the structure-activity relationships of the new compounds by performing several in vivo assays.

The work is very interesting and meaningful and provides new tools undoubtedly useful for basic research. The preliminary data they provide on cellular models of disease are encouraging and contains promising for future applications. I have only a few comments on data presentation.

The introduction is minimalist. The part related to possible effects of piperine on mitochondria and the information about small molecules promoting mitochondrial fusion should be expanded to provide sufficient background even for "non-expert" readers.

The Material and method sections is very poor, and it would be difficult, starting from the authors’ description, to reproduce the experiments. For example, how was EC50 evaluated? How was mitochondrial mobility assessed? Furthermore, please, organize the section in paragraphs. Here just few suggestions: mitochondria staining and observation. Image analysis. Plasma protein binding assay. Liver microsome stability assay. Passive artificial membrane permeability.

The discussion could be expanded. For example, the authors may speculate more on new biologic features of compounds.

Figure legend 2. In this version, it is difficult to distinguish the figure caption from the text

Figure 3. please describe how %depolarized mito has been evaluated

Author Response

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Author Response File: Author Response.docx

Round 2

Reviewer 1 Report

The revised manuscript has been improved significantly.