Cycle Numbers of Cell Surface Recycling Receptors

Round 1

Reviewer 1 Report

In this manuscript, the author addresses an extremely important topic: functional longevity, which serves as a receptor for a macromolecule in the cell. He also lays out how this criterion can be used to distinguish between physiologically "normal" cells and cancer cells, which again is an important aspect of cancer research.

This is good information. Well written and clearly presented. Just a few suggestions to highlight some important aspects.

1 - As for the title, and just to emphasize the relevance of the concept, this reviewer suggests that a term referring to a cell might be more attractive. For example, "Cycle Numbers of Cell Surface Receptors Recycling."

2 - I also suggest adding the term "cancer" to the keywords.

3 - In section 3, it is probably of interest that the author contrasts his proposed model with the kinetic aspects analyzed by Bajzer et al. 1989 (J Biol Chem. 1989 Aug 15;264(23):13623-31).

4 - It would be useful to attempt to explain or discuss, at least in part, the biological significance or impact of the reduction in nc values from a previously calculated range of 300-1000 to a newly determined range of 38-240 (a whole order of magnitude less). Perhaps a brief biological argument can be added in Section 4 on the implications of this real reduction from previous calculations to the present.

5.    On the other hand, it is again extremely important to emphasize this reduction in nc values by an order of magnitude between cancer cells (38-79 cycle numbers) and cycle numbers (144-237) in physiologically normal cells. Therefore, I suggest that lines 108 to 133 constitute a new section 5, possibly named: "Cycle number of recycling receptors to distinguish between cancer and normal cells".

Author Response

In this manuscript, the author addresses an extremely important topic: functional longevity, which serves as a receptor for a macromolecule in the cell. He also lays out how this criterion can be used to distinguish between physiologically "normal" cells and cancer cells, which again is an important aspect of cancer research.

This is good information. Well written and clearly presented. Just a few suggestions to highlight some important aspects. Reply: I thank the reviewer for their time reviewing the manuscript and for their comments that helped to improve the article.

1. As for the title, and just to emphasize the relevance of the concept, this reviewer suggests that a term referring to a cell might be more attractive. For example, "Cycle Numbers of Cell Surface Receptors Recycling." Reply: As suggested by the reviewer, the title has been changed accordingly (see page 1, line 2).
2. I also suggest adding the term "cancer" to the keywords. Reply: The term “cancer cells” has been added to the list of keywords (see page 1, line 17).
3. In section 3, it is probably of interest that the author contrasts his proposed model with the kinetic aspects analyzed by Bajzer et al. 1989 (J Biol Chem. 1989 Aug 15;264(23):13623-31). Reply: I am familiar with the paper by Bajzer et al. 1989. This study reports the derivation of mathematical models to explain the internalization of ligand-receptor complexes based on kinetic rate constants. Although some models include receptor recycling for the best fit of data, the study does not analyze the recycling of receptors per se. From the rate constants for the internalization and recycling of receptors reported in the paper, receptor cycling times can be calculated, but these cycling times are much higher (around 2 h) than measured receptor cycling times which range between 7-21 min (see Table 2). Therefore, it is questionable whether the mathematical models correctly reflect the recycling of receptors. In addition, no information regarding receptor cycle numbers and receptor half-lives is provided in the study by Bajzer. Thus, there is no point to discuss and compare the work by Bajzer with the results of my study.
4. It would be useful to attempt to explain or discuss, at least in part, the biological significance or impact of the reduction in nc values from a previously calculated range of 300-1000 to a newly determined range of 38-240 (a whole order of magnitude less). Perhaps a brief biological argument can be added in Section 4 on the implications of this real reduction from previous calculations to the present. Reply: The implication of lower nc values is now discussed in Section 4 (see pages 4-5, lines 104-110).
5. On the other hand, it is again extremely important to emphasize this reduction in nc values by an order of magnitude between cancer cells (38-79 cycle numbers) and cycle numbers (144-237) in physiologically normal cells. Therefore, I suggest that lines 108 to 133 constitute a new section 5, possibly named: "Cycle number of recycling receptors to distinguish between cancer and normal cells". Reply: As suggested by the reviewer, a new section 5 has been created that discusses the differences between the cycle numbers of cancer and normal cells. The headline of this section is “Cycle Number of Recycling Receptors Distinguishes between Normal and Cancer Cells”. (see pages 5-6, lines 113-148).

Reviewer 2 Report

Only one comment: does the ligand-induced signalling by the receptor affect latter's cycle number?

Author Response

Only one comment: does the ligand-induced signalling by the receptor affect latter's cycle number? Reply: I thank the reviewer for their time in critically reading of the manuscript. The possibility that ligand-induced signaling may affect the cycle number of receptors is now discussed in the manuscript (see page 5, lines 130-137).

Reviewer 3 Report

Reviewers’ comments for the Manuscript ID:

The manuscript title: Cycle Numbers of Recycling Receptors

In this short communication the author “Dietmar Steverding” conducted an interesting study related to receptors cycling number (nc), cycling time (Tc) and their half-life (t1/2) before they are degraded in the endosomes. It is a specific and interesting topic, nicely written and can be suitable for publication in “Receptors” after addressing two comments below.

Comments

11) Schematic representation of recycling of receptors should be included in the manuscript.

22)   Detailed methods are missing; it should be included in the manuscript or as a supporting information file.

Author Response

In this short communication the author “Dietmar Steverding” conducted an interesting study related to receptors cycling number (nc), cycling time (Tc) and their half-life (t1/2) before they are degraded in the endosomes. It is a specific and interesting topic, nicely written and can be suitable for publication in “Receptors” after addressing two comments below. Reply: I thank the reviewer for the evaluation of the manuscript and their useful comments.

1. Schematic representation of recycling of receptors should be included in the manuscript. Reply: As suggested by the reviewer, a schematic diagram explaining the recycling of surface receptors has been included in the manuscript (see page 1, lines 28-31). Also, the text of the Introduction has been expanded (see page 1, lines 22-27).
2. Detailed methods are missing; it should be included in the manuscript or as a supporting information file. Reply: All methods have been described in the manuscript. The main method is using Equation 6 for the calculation of the cycle number. The derivation of Equation 6 has been explained in detail (see page 2, lines 45-60). The half-lives and cycling times of classical surface receptors used for the calculation of cycle numbers presented in Table 2 were taken from the literature. The sources of half-lives and cycling times are indicated in Table 2 and this fact has now been mentioned in the table header (see page 5, lines 110-111). Also, it is now mentioned in the header of Table 1 and in the legend of Figure 1 that the cycle numbers were calculated using Equation 6 (see page 4, line 92, and page 3, lines 81-82). The 3D plot shown in Figure 3 was created with the GeoGebra 3D Calculator, which is mentioned in the figure legend and referenced (see page 3, line 64, and page 6, line 173). No other methods were used.

Round 2

Reviewer 1 Report

The author has dealt with the questions and comments, so that the manuscript has gained precision.

Reviewer 2 Report

The authors have adequately addressed my concerns.

Reviewer 3 Report

Nicely revised the manuscript and can be accepted in its current form.

Best,