Expression of a diverse array of Ca²⁺-activated K⁺ 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 Ca²⁺-activated K⁺ 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

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:	Creators Email Pitt Username ORCID Li, Y Hu, H Butterworth, MB michael7@pitt.edu MICHAEL7 Tian, JB Zhu, MX O'Neil, RG
Contributors:	Contribution Contributors Name Email Pitt Username ORCID Editor Obukhov, Alexander G. UNSPECIFIED UNSPECIFIED UNSPECIFIED
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:	11 Jun 2021 22:55
URI:	http://d-scholarship.pitt.edu/id/eprint/28259

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