Chloride channel activity in human lung fibroblasts and myofibroblasts.
It is well established that transforming growth factor (TGF)-beta stimulates human lung fibroblasts (HLF) to differentiate into myofibroblasts. We characterized lysophosphatidic acid (LPA)-activated Cl- channel current (I(Cl-LPA)) in cultured human lung fibroblasts and myofibroblasts and investigated the influence of I(Cl-LPA) on fibroblast-to-myofibroblast differentiation. We recorded I(Cl-LPA) using the amphotericin perforated-patch technique. We activated I(Cl-LPA) using LPA or sphingosine-1-phosphate. We determined phenotype by Western blotting and immunohistochemistry using an anti-alpha-smooth muscle actin (SMA) antibody. RT-PCR was performed to determine which phospholipid growth factor receptors are present in HLF. We found that HLF cultured in TGF-beta (myofibroblasts) had significantly elevated alpha-SMA levels and I(Cl-LPA) current density compared with control fibroblasts. I(Cl-LPA) activation was blocked by DIDS, 5-nitro-2-(3-phenylpropylamino)benzoic acid (NPPB), and the LPA receptor-specific antagonist dioctyl-glycerol pyrophosphate (1 microM). DIDS and NPPB, in a dose-dependent manner, significantly reduced alpha-SMA levels in HLF stimulated with TGF-beta. These results demonstrate the receptor-mediated activation of I(Cl-LPA) by LPA and sphingosine-1-phosphate in cultured human lung myofibroblasts, with only minimal I(Cl-LPA) activity in fibroblasts. This Cl- channel activity appears to play a critical role in the differentiation of human lung fibroblasts to myofibroblasts.
Yin
Zhaohong
Z
Dept. of Physiology, Univ. of Tennessee Health Science Center, 894 Union Ave., Memphis, TN 38163, USA.
Watsky
Mitchell A
MA
D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid / Q000494:pharmacology; D000199:Actins / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000378:metabolism; D002454:Cell Differentiation; D002478:Cells, Cultured; D018118:Chloride Channels / Q000037:antagonists & inhibitors / Q000502:physiology*; D004594:Electrophysiology; D005333:Fetus; D005347:Fibroblasts / Q000187:drug effects / Q000378:metabolism*; D006801:Humans; D008168:Lung / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D008246:Lysophospholipids / Q000494:pharmacology; D009130:Muscle, Smooth / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D009579:Nitrobenzoates / Q000494:pharmacology; D049368:Receptors, Lysophosphatidic Acid / Q000037:antagonists & inhibitors / Q000378:metabolism; D013110:Sphingosine / Q000031:analogs & derivatives* / Q000494:pharmacology; D016212:Transforming Growth Factor beta / Q000494:pharmacology
D000199:Actins; D018118:Chloride Channels; D008246:Lysophospholipids; D009579:Nitrobenzoates; D049368:Receptors, Lysophosphatidic Acid; D016212:Transforming Growth Factor beta; C060506:sphingosine 1-phosphate; C058176:5-nitro-2-(3-phenylpropylamino)benzoic acid; D000255:Adenosine Triphosphate; D013110:Sphingosine; C032881:lysophosphatidic acid; D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid