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Questions concerning this paper

Posted by bdieriks on 25 Nov 2010 at 09:22 GMT

Dear authors,

I would like to take this opportunity to ask you some questions in order to clarify some parts of you latest article: “Cyclophilin B Interacts with Sodium-Potassium ATPase and Is Required for Pump Activity in Proximal Tubule Cells of the Kidney”
In this article it is stated that the Na/κ-β1 localization is compatible with the ER and co-locates with CypB. This does not follow from Fig 2. From the inset magnification it looks like both proteins are only colocalizing on a few locations and this is mostly apparent at the side of the CypB spots. It looks like there is so much CypB and Na/κ-β1 present in the cells that the overlap could be purely coincidental or due to out of focus light. Did you perform a quantitative colocalization analysis on these images?

I wonder why the CsA treated cells from Fig 3D-E show a nuclear localization for Na/κ-β1 and CypB. Whereas the cells shown in Fig 5B, which also received a CsA treatment have almost no Na/κ-β1 or CypB staining. Here only a decrease in Na/κ-β1/CypB intensity and no nuclear staining is observed.

In Fig 5C: You indicate the ER with yellow arrows. Has this been confirmed with other ER markers? For instance the Na/κ-β1 staining in the upper right cell in Fig 5C has more the appearance of Golgi.

In Fig 5 you state that no Na/κ-β1 is found in the plasma membrane after CypB silencing. Looking at the intensities of the plasma membrane staining of the controls in Fig 5A it is not different from the plasma staining in the upper left cell in 5C. In the controls the plasma membrane staining is not so apparent. Also in Fig 2 the plasma staining is not clearly seen. Only in the cells with a narrow cytoplasm between nucleus and plasma membrane this is clearly seen. Do you have an explanation for this variability?

No competing interests declared.
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