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Expression of a diverse array of Ca<sup>2+</sup>-activated K<sup>+</sup> channels (SK1/3, IK1, BK) that functionally couple to the mechanosensitive TRPV4 channel in the collecting duct system of kidney

Li, Y and Hu, H and Butterworth, MB and Tian, JB and Zhu, MX and O'Neil, RG (2016) Expression of a diverse array of Ca<sup>2+</sup>-activated K<sup>+</sup> channels (SK1/3, IK1, BK) that functionally couple to the mechanosensitive TRPV4 channel in the collecting duct system of kidney. PLoS ONE, 11 (5).

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Abstract

© 2016 Li et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. The voltage- and Ca2+-activated, large conductance K+ channel (BK, maxi-K) is expressed in the collecting duct system of kidney where it underlies flow- and Ca2+-dependent K+ excretion. To determine if other Ca2+-activated K+ channels (KCa) may participate in this process, mouse kidney and the K+-secreting mouse cortical collecting duct (CCD) cell line, mCCDcl1, were assessed for TRPV4 and KCa channel expression and cross-talk. qPCR mRNA analysis and immunocytochemical staining demonstrated TRPV4 and KCa expression in mCCDcl1 cells and kidney connecting tubule (CNT) and CCD. Three subfamilies of KCa channels were revealed: the high Ca2+-binding affinity small-conductance SK channels, SK1and SK3, the intermediate conductance channel, IK1, and the low Ca2+-binding affinity, BK channel (BKα subunit). Apparent expression levels varied in CNT/CCD where analysis of CCD principal cells (PC) and intercalated cells (IC) demonstrated differential staining: SK1:PC<IC, and SK3:PC>IC, IK1:PC>IC, BKα:PC = IC, and TRPV4:PC>IC. Patch clamp analysis and fluorescence Ca2+ imaging of mCCDcl1 cells demonstrated potent TRPV4-mediated Ca2+ entry and strong functional cross-talk between TRPV4 and KCa channels. TRPV4-mediated Ca2+ influx activated each KCa channel, as evidenced by selective inhibition of KCa channels, with each active KCa channel enhancing Ca2+ entry (due to membrane hyperpolarization). Transepithelial electrical resistance (TEER) analysis of confluent mCCDcl1 cells grown on permeable supports further demonstrated this cross-talk where TRPV4 activation induce a decrease in TEER which was partially restored upon selective inhibition of each KCa channel. It is concluded that SK1/SK3 and IK1 are highly expressed along with BKα in CNT and CCD and are closely coupled to TRPV4 activation as observed in mCCDcl1 cells. The data support a model in CNT/CCD segments where strong cross talk between TRPV4-mediated Ca2+ influx and each KCa channel leads to enhance Ca2+ entry which will support activation of the low Ca2+-binding affinity BK channel to promote BK-mediated K+ secretion.


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Details

Item Type: Article
Status: Published
Creators/Authors:
CreatorsEmailPitt UsernameORCID
Li, Y
Hu, H
Butterworth, MBmichael7@pitt.eduMICHAEL7
Tian, JB
Zhu, MX
O'Neil, RG
Contributors:
ContributionContributors NameEmailPitt UsernameORCID
EditorObukhov, Alexander G.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Date: 1 May 2016
Date Type: Publication
Access Restriction: No restriction; Release the ETD for access worldwide immediately.
Journal or Publication Title: PLoS ONE
Volume: 11
Number: 5
DOI or Unique Handle: 10.1371/journal.pone.0155006
Institution: University of Pittsburgh
Schools and Programs: School of Medicine > Cell Biology
Refereed: Yes
Date Deposited: 31 Aug 2016 18:06
Last Modified: 25 Jan 2019 23:55
URI: http://d-scholarship.pitt.edu/id/eprint/28259

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