Expression of chloride channel, ClC-5, and its role in receptor-mediated endocytosis of albumin in OK cells.
By using Western blot and RT-PCR analyses, the expression of ClC-5, a member of the ClC family of voltage-gated chloride channels, and its mRNA was detected in OK cells. The effect of chloride channel inhibitors on receptor-mediated endocytosis of albumin was examined in OK cells and compared to that of vacuolar H(+)-ATPase inhibitors. Accumulation of fluorescein-isothiocyanate (FITC)-albumin, a receptor-mediated endocytosis marker, was inhibited by 5-nitro-2-(3-phenylpropylamino)-benzoic acid (NPPB), a chloride channel inhibitor, in a concentration-dependent fashion. In contrast, uptake of FITC-inulin, a fluid-phase endocytosis marker, was not affected by NPPB. Other chloride channel inhibitors, 4,4'-diisothiocyanatostilbene-2-2'-disulfonic acid and diphenylamine-2-carboxylic acid, also inhibited FITC-albumin uptake. NPPB, as well as a vacuolar H(+)-ATPase inhibitor bafilomycin A(1), caused a decrease in the affinity and in the maximal velocity of FITC-albumin uptake. These results suggest that chloride channel, most likely ClC-5, plays an important role in the receptor-mediated endocytosis of albumin in OK cells.
Sasaki
Y
Y
Institute of Pharmaceutical Sciences, Faculty of Medicine, Hiroshima University, 1-2-3 Kasumi, Minami-ku, Hiroshima, 734-8551, Japan.
Nagai
J
J
Kitahara
Y
Y
Takai
N
N
Murakami
T
T
Takano
M
M
D000418:Albumins / Q000378:metabolism*; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002460:Cell Line; D018118:Chloride Channels / Q000235:genetics* / Q000502:physiology; D004705:Endocytosis / Q000502:physiology*; D016650:Fluorescein-5-isothiocyanate; D007700:Kinetics; D008969:Molecular Sequence Data; D009893:Opossums; D011956:Receptors, Cell Surface / Q000502:physiology*; D020133:Reverse Transcriptase Polymerase Chain Reaction
D000418:Albumins; C097503:CLC-5 chloride channel; D018118:Chloride Channels; D011956:Receptors, Cell Surface; D016650:Fluorescein-5-isothiocyanate