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DNPEP is not the only peptidase that produces SPAK fragments in kidney

SPAK (STE20/SPS1‐related proline/alanine‐rich kinase) regulates Na(+) and Cl(−) reabsorption in the distal convoluted tubule, and possibly in the thick ascending limb of Henle. This kinase phosphorylates and activates the apical Na‐Cl cotransporter in the DCT. Western blot analysis reveals that SPAK...

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Autores principales: Koumangoye, Rainelli, Delpire, Eric
Formato: Online Artículo Texto
Lenguaje:English
Publicado: John Wiley and Sons Inc. 2017
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5688775/
https://www.ncbi.nlm.nih.gov/pubmed/29122955
http://dx.doi.org/10.14814/phy2.13479
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author Koumangoye, Rainelli
Delpire, Eric
author_facet Koumangoye, Rainelli
Delpire, Eric
author_sort Koumangoye, Rainelli
collection PubMed
description SPAK (STE20/SPS1‐related proline/alanine‐rich kinase) regulates Na(+) and Cl(−) reabsorption in the distal convoluted tubule, and possibly in the thick ascending limb of Henle. This kinase phosphorylates and activates the apical Na‐Cl cotransporter in the DCT. Western blot analysis reveals that SPAK in kidney exists as a full‐length protein as well as shorter fragments that might affect NKCC2 function in the TAL. Recently, we showed that kidney lysates exerts proteolytic activity towards SPAK, resulting in the formation of multiple SPAK fragments with possible inhibitory effects on the kinase. The proteolytic activity is mediated by a Zn(2+) metalloprotease inhibited by 1,10‐phenanthroline, DTT, and EDTA. Size exclusion chromatography demonstrated that the protease was a high‐molecular‐weight protein. Protein identification by mass‐spectrometry analysis after ion exchange and size exclusion chromatography identified multiple proteases as possible candidates and aspartyl aminopeptidase, DNPEP, shared all the properties of the kidney lysate activity. Furthermore, recombinant GST‐DNPEP produced similar proteolytic pattern. No mouse knockout model was, however, available to be used as negative control. In this study, we used a DNPEP‐mutant mouse generated by EUCOMM as well as a novel CRISPR/cas9 mouse knockout to assess the activity of their kidney lysates towards SPAK. Two mouse models had to be used because different anti‐DNPEP antibodies provided conflicting data on whether the EUCOMM mouse resulted in a true knockout. We show that in the absence of DNPEP, the kidney lysates retain their ability to cleave SPAK, indicating that DNPEP might have been misidentified as the protease behind the kidney lysate activity, or that the aspartyl aminopeptidase might not be the only protease cleaving SPAK in kidney.
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spelling pubmed-56887752017-11-24 DNPEP is not the only peptidase that produces SPAK fragments in kidney Koumangoye, Rainelli Delpire, Eric Physiol Rep Original Research SPAK (STE20/SPS1‐related proline/alanine‐rich kinase) regulates Na(+) and Cl(−) reabsorption in the distal convoluted tubule, and possibly in the thick ascending limb of Henle. This kinase phosphorylates and activates the apical Na‐Cl cotransporter in the DCT. Western blot analysis reveals that SPAK in kidney exists as a full‐length protein as well as shorter fragments that might affect NKCC2 function in the TAL. Recently, we showed that kidney lysates exerts proteolytic activity towards SPAK, resulting in the formation of multiple SPAK fragments with possible inhibitory effects on the kinase. The proteolytic activity is mediated by a Zn(2+) metalloprotease inhibited by 1,10‐phenanthroline, DTT, and EDTA. Size exclusion chromatography demonstrated that the protease was a high‐molecular‐weight protein. Protein identification by mass‐spectrometry analysis after ion exchange and size exclusion chromatography identified multiple proteases as possible candidates and aspartyl aminopeptidase, DNPEP, shared all the properties of the kidney lysate activity. Furthermore, recombinant GST‐DNPEP produced similar proteolytic pattern. No mouse knockout model was, however, available to be used as negative control. In this study, we used a DNPEP‐mutant mouse generated by EUCOMM as well as a novel CRISPR/cas9 mouse knockout to assess the activity of their kidney lysates towards SPAK. Two mouse models had to be used because different anti‐DNPEP antibodies provided conflicting data on whether the EUCOMM mouse resulted in a true knockout. We show that in the absence of DNPEP, the kidney lysates retain their ability to cleave SPAK, indicating that DNPEP might have been misidentified as the protease behind the kidney lysate activity, or that the aspartyl aminopeptidase might not be the only protease cleaving SPAK in kidney. John Wiley and Sons Inc. 2017-11-09 /pmc/articles/PMC5688775/ /pubmed/29122955 http://dx.doi.org/10.14814/phy2.13479 Text en © 2017 The Authors. Physiological Reports published by Wiley Periodicals, Inc. on behalf of The Physiological Society and the American Physiological Society. This is an open access article under the terms of the Creative Commons Attribution (http://creativecommons.org/licenses/by/4.0/) License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.
spellingShingle Original Research
Koumangoye, Rainelli
Delpire, Eric
DNPEP is not the only peptidase that produces SPAK fragments in kidney
title DNPEP is not the only peptidase that produces SPAK fragments in kidney
title_full DNPEP is not the only peptidase that produces SPAK fragments in kidney
title_fullStr DNPEP is not the only peptidase that produces SPAK fragments in kidney
title_full_unstemmed DNPEP is not the only peptidase that produces SPAK fragments in kidney
title_short DNPEP is not the only peptidase that produces SPAK fragments in kidney
title_sort dnpep is not the only peptidase that produces spak fragments in kidney
topic Original Research
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5688775/
https://www.ncbi.nlm.nih.gov/pubmed/29122955
http://dx.doi.org/10.14814/phy2.13479
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