ClC-3 is required for LPA-activated Cl- current activity and fibroblast-to-myofibroblast differentiation

• Published in: American Journal of Physiology: Cell Physiology Vol. 294; no. 2; pp. C535 - C542
• Main Authors: Yin, Zhaohong, Tong, Yiai, Zhu, Haiqing, Watsky, Mitchell A
• Format: Journal Article
• Language: English
• Published: United States 01.02.2008
• Subjects: Actins - metabolism; Cell Differentiation - genetics; Cell Line; Cell Size - drug effects; Chloride Channels - genetics; Chlorides - metabolism; Down-Regulation - drug effects; Down-Regulation - genetics; Fibroblasts - cytology; Fibroblasts - drug effects; Fibroblasts - metabolism; Fibrosis - metabolism; Fibrosis - physiopathology; Flow Cytometry; Humans; Keratinocytes - cytology; Keratinocytes - drug effects; Keratinocytes - metabolism; Lysophospholipids - pharmacology; Membrane Potentials - drug effects; Membrane Potentials - genetics; Myocytes, Smooth Muscle - cytology; Myocytes, Smooth Muscle - drug effects; Myocytes, Smooth Muscle - metabolism; Patch-Clamp Techniques; RNA Interference; Transforming Growth Factor beta1 - metabolism; Transforming Growth Factor beta1 - pharmacology; Wound Healing - physiology
• ISSN: 0363-6143; 1522-1563
• DOI: 10.1152/ajpcell.00291.2007

Departments of 1 Physiology and 2 Anatomy and Neurobiology, University of Tennessee Health Science Center, Memphis, Tennessee; and 3 Department of Pathology, St. Jude Children's Research Hospital, Memphis, Tennessee Submitted 9 July 2007 ; accepted in final form 7 December 2007 To determine the effects of chloride channel 3 (ClC-3) knockdown and overexpression on lysophosphatidic acid (LPA)- and volume-regulated anion channel Cl – currents ( I Cl,LPA and I Cl,VRAC , respectively), cell differentiation, and cell volume regulation, a short hairpin RNA (shRNA) expression system based on a mouse U6 promoter was used to knock down ClC-3 in human corneal keratocytes and human fetal lung fibroblasts. ClC-3 overexpression was achieved by electroporating full-length ClC-3, within a pcDNA3.1 vector, into these two cell lines. RT-PCR and Western blot analysis were used to detect ClC-3 mRNA and protein levels. Whole cell perforated patch-clamp recording was used to measure I Cl,LPA and I Cl,VRAC currents, and fluorescence-activated cell sorting analysis was used to measure cell volume regulation. ClC-3 knockdown significantly decreased I Cl,LPA and I Cl,VRAC activity in the presence of transforming growth factor-β 1 (TGF-β 1 ) compared with controls, whereas ClC-3 overexpression resulted in increased I Cl,LPA activity in the absence of TGF-β 1 . ClC-3 knockdown also resulted in a reduction of -smooth muscle actin ( -SMA) protein levels in the presence of TGF-β 1 , whereas ClC-3 overexpression increased -SMA protein expression in the absence of TGF-β 1 . In addition, keratocytes transfected with ClC-3 shRNA had a significantly blunted regulatory volume decrease response following hyposmotic stimulation compared with controls. These data confirm that ClC-3 is important in VRAC function and cell volume regulation, is associated with the I Cl,LPA current activity, and participates in the fibroblast-to-myofibroblast transition. chloride channel-3; lysophosphatidic acid; cornea; lung; keratocyte Address for reprint requests and other correspondence: M. A. Watsky, Dept. of Physiology, Univ. of Tennessee Health Science Center, 894 Union Ave., Memphis, TN 38163 (e-mail: mwatsky{at}physio1.utmem.edu )