Sodium Channels Involved in the Initiation of Action Potentials in Invertebrate and Mammalian Neurons
Round 1
Reviewer 1 Report
The authors review the voltage-activated Na+-selective channels (Navs) of vertebrates and invertebrates comparing them from the point of view of distribution, evolution and function.
Line 18 – Put a period after the papers and separate the sentence from Current.
Line 210-211: the references “...McDermott et al., 2019; Middleton et al., 2021; Goodwin & McMahon, 2021”, It has a different source than the others.
In the supplementary file put a caption, what does each color highlighted in the alignment mean? comment further in the text.
Author Response
Dear editor and reviewers,
Thank you for your consideration and helpful comments. Here, we resubmit a revised version of the manuscript edited and improved according to your suggestions. We addressed your points, rechecked the references, and improved the text quality by professional proofreading.
Reviewer #1.
>Line 18 – Put a period after the papers and separate the sentence from Current.
Done
>Line 210-211: the references “...McDermott et al., 2019; Middleton et al., 2021; Goodwin & McMahon, 2021”, It has a different source than the others.
Done
>In the supplementary file put a caption, what does each color highlighted in the alignment mean? comment further in the text.
Legend added to the supplementary file.
Reviewer 2 Report
In this review article, the authors reported the subtle variability in sodium channels involved in initiation of action potentials in invertebrate and mammalian neurons. A few queries regarding this manuscript are shown in the following:
Major comments:
[1] The Na+ channels are widely distributed in both invertebrate and vertebrate neurons. During the last decade, the increased knowledge about causative genetic variants has had a great impact on the development of precision treatments for epilepsy and neuropathic pain. Most epileptogenic NaV variants lie within NaV1.1, and a few lie within NaV1.2, NaV1.3, or NaV1.6. Causative genetic variants in NaV1.7, NaV1.8, or NaV1.9 are linked to neuropathic pain. Currently, the lack of direct evidence discriminating the actions of small molecules on specific NaV isoforms occurs. The information relevant to this issue should be included in the Conclusion section.
[2] In Figure 1, the number of Na or K channels shown could be inappropriately illustrated. Change in NaV channels during emergence of neuronal action potential could be modified by inactivation process, rather than by the number of ionic channels, or mean open time of the channels, or both. It is better to be shown in macroscopic conductance or ionic currents.
[3] A lack of the graph showed the representative traces (electrophysiological results) regarding different isoforms of voltage-gated Na+ currents, although Table 1 illustrates the difference in some parameters. Please describe some of limitations in this review paper.
[4] Please show the possible difference in the actions of pyrethroids, known to be an insecticide, on INa between invertebrate and vertebrate neurons (or between insect and mammalian neurons).
[5] Please also show some characteristics of NaV channels in neuroendocrine or endocrine cells.
Minor comments:
[1] In line 12, the sentence should be changed to “…should be activated faster …”.
[2] In line 18, “…rolesCurrent…” is incorrect.
[3] In lines 26-27, the sentence (…. Is not exclusive to animals.) needs to be rephrased for clarity.
[4] In line 44, “Kav” should be replaced with “Kv”.
[5] In line 50, AP trace should be shown at “red curve”. Blue curve indicates the Na+ channels.
[3] In line 50, “K+ channel” should be replaced with “K+ channel”.
[4] In line 145, “Na2+” should be replaced with “Na+”.
[5] In Table 1, please explain the meaning of “time to 1/2 peak” (line 147).
[6] In Figures 2 and 3, please include the references to show where the graphs were obtained.
Author Response
Dear editor and reviewers,
Thank you for your consideration and helpful comments. Here, we resubmit a revised version of the manuscript edited and improved according to your suggestions. We addressed your points, rechecked the references, and improved the text quality by professional proofreading.
Reviewer #2.
Major comments:
[1] The Na+ channels are widely distributed in both invertebrate and vertebrate neurons. During the last decade, the increased knowledge about causative genetic variants has had a great impact on the development of precision treatments for epilepsy and neuropathic pain. Most epileptogenic NaV variants lie within NaV1.1, and a few lie within NaV1.2, NaV1.3, or NaV1.6. Causative genetic variants in NaV1.7, NaV1.8, or NaV1.9 are linked to neuropathic pain. Currently, the lack of direct evidence discriminating the actions of small molecules on specific NaV isoforms occurs. The information relevant to this issue should be included in the Conclusion section.
We added to the conclusion section:
Most epileptogenic NaV variants are associated within NaV1.1, NaV1.2, NaV1.3, or NaV1.6, whereas genetic variants in NaV1.7, NaV1.8, or NaV1.9 are linked to neuropathic pain. However, the current lack of highly specific channel blockers/activators limits functional characterization of each isoform.
[2] In Figure 1, the number of Na or K channels shown could be inappropriately illustrated. Change in NaV channels during emergence of neuronal action potential could be modified by inactivation process, rather than by the number of ionic channels, or mean open time of the channels, or both. It is better to be shown in macroscopic conductance or ionic currents.
Changed according to reviewer’s suggestions
[3] A lack of the graph showed the representative traces (electrophysiological results) regarding different isoforms of voltage-gated Na+ currents, although Table 1 illustrates the difference in some parameters. Please describe some of limitations in this review paper.
We could add some electrophysiological traces, but we believe that it would not add a lot to the main subject of this review. The rising fronts of NaV1-mediated fast currents in heterologous expression systems looks exactly like Na-current in Fig 1. However, the traces usually differ in non-inactivating persistent currents (i.e. in the descending phase), which will add confusing information, which is out of the scope of this work.
On the other hand, the traces of real neurons are strongly influenced by current dissection protocols and differ in the ascending phases as well, which we won’t explain because it is out of the scope of this work and does not contribute to AP initiation.
[4] Please show the possible difference in the actions of pyrethroids, known to be an insecticide, on INa between invertebrate and vertebrate neurons (or between insect and mammalian neurons).
We added to the insect section:
The difference between pharmacological characteristics of insect NaV channels and those of mammals allowed to construct specific molecules that acting on insect NaVs with virtually no effect on mammalian NaVs. The best known example is synthetic pyrethroids that are toxic to insects with very low toxicity to mammals (Field et al., 2017).
[5] Please also show some characteristics of NaV channels in neuroendocrine or endocrine cells.
We added to the text:
In neuroendocrine cells, fast NaV1.3 and NaV1.7 channels were shown to contribute to AP generation and firing patters (Vandael et al., 2015).
Minor comments:
[1] In line 12, the sentence should be changed to “…should be activated faster …”.
done
[2] In line 18, “…rolesCurrent…” is incorrect.
Done
[3] In lines 26-27, the sentence (…. Is not exclusive to animals.) needs to be rephrased for clarity.
Replaced with “limited”
[4] In line 44, “Kav” should be replaced with “Kv”.
done
[5] In line 50, AP trace should be shown at “red curve”. Blue curve indicates the Na+ channels.
fixed
[3] In line 50, “K+ channel” should be replaced with “K+ channel”.
We missed the point, as the words within the brackets are apparently identical
[4] In line 145, “Na2+” should be replaced with “Na+”.
done
[5] In Table 1, please explain the meaning of “time to 1/2 peak” (line 147).
Text added: times-to-halfpeak (the length of time it takes to reach half-peak activation)
[6] In Figures 2 and 3, please include the references to show where the graphs were obtained.
Sequence data were obtained from Genbank and are available online.
Round 2
Reviewer 2 Report
The queries have been answered by the investigators. A few queries shown below remains.
(1) In Figure 1, the labelling of y-axis (mS/sm2) is incorrect is incorrect and needs to be corrected.
(2) The text “InaT” or “INaT” appearing throughout the text of the manuscript should be appropriately changed to INaT.
(3) In page 1, line 3 from the bottom, voltage-dependent K+ currents should be changed to voltage-dependent K+ currents.
Author Response
Dear reviewer,
Thank you for spotting our minor mistakes. Please find the corrected version of our manuscript in the file submitted.
(1) In Figure 1, the labelling of y-axis (mS/sm2) is incorrect is incorrect and needs to be corrected.
Changed to mS/cm2
(2) The text “InaT” or “INaT” appearing throughout the text of the manuscript should be appropriately changed to INaT.
done
(3) In page 1, line 3 from the bottom, voltage-dependent K+ currents should be changed to voltage-dependent K+ currents.
done
