Cardiac-specific, inducible ClC-3 gene deletion eliminates native volume-sensitive chloride channels and produces myocardial hypertrophy in adult mice.
Native volume-sensitive outwardly rectifying anion channels (VSOACs) play a significant role in cell volume homeostasis in mammalian cells. However, the molecular correlate of VSOACs has been elusive to identify. The short isoform of ClC-3 (sClC-3) is a member of the mammalian ClC gene family and has been proposed to be a molecular candidate for VSOACs in cardiac myocytes and vascular smooth muscle cells. To directly test this hypothesis, and assess the physiological role of ClC-3 in cardiac function, we generated a novel line of cardiac-specific inducible ClC-3 knock-out mice. These transgenic mice were maintained on a doxycycline diet to preserve ClC-3 expression; removal of doxycycline activates Cre recombinase to inactivate the Clcn3 gene. Echocardiography revealed dramatically reduced ejection fraction and fractional shortening, and severe signs of myocardial hypertrophy and heart failure in the knock-out mice at both 1.5 and 3 weeks off doxycycline. In mice off doxycycline, time-dependent inactivation of ClC-3 gene expression was confirmed in atrial and ventricular cells by qRT-PCR and Western blot analysis. Electrophysiological examination of native VSOACs in isolated atrial and ventricular myocytes 3 weeks off doxycycline revealed a complete elimination of the currents, whereas at 1.5 weeks, VSOAC current densities were significantly reduced, compared to age-matched control mice maintained on doxycycline. These results indicate that ClC-3 is a key component of native VSOACs in mammalian heart and plays a significant cardioprotective role against cardiac hypertrophy and failure.
Xiong
Dazhi
D
Center of Biomedical Research Excellence, Department of Pharmacology, MS 318, University of Nevada School of Medicine, Reno, NV 89557, USA.
Heyman
Nathanael S
NS
Airey
Judith
J
Zhang
Mi
M
Singer
Cherie A
CA
Rawat
Shanti
S
Ye
Linda
L
Evans
Rebecca
R
Burkin
Dean J
DJ
Tian
Honglin
H
McCloskey
Diana T
DT
Valencik
Maria
M
Britton
Fiona C
FC
Duan
Dayue
D
Hume
Joseph R
JR
D000818:Animals; D015153:Blotting, Western; D001921:Brain / Q000378:metabolism; D006332:Cardiomegaly / Q000235:genetics*; D002478:Cells, Cultured; D018118:Chloride Channels / Q000235:genetics / Q000378:metabolism*; D017353:Gene Deletion; D006321:Heart / Q000503:physiopathology*; D007150:Immunohistochemistry; D051379:Mice; D018345:Mice, Knockout; D009206:Myocardium / Q000378:metabolism* / Q000473:pathology*; D016133:Polymerase Chain Reaction
D018118:Chloride Channels; C115376:ClC-3 channel