| Subjects |
Study on the Role of Aquaporin Water Channel in Cell Volume Regulation |
| Representative researcher |
National Institute for Physiological Sciences Yasunobu
OKADA |
| Joint researcher |
National Institute for Physiological Sciences Kenichi
MANABE |
| National Institute for Physiological Sciences Hajime
KIDA |
| National Institute for Physiological Sciences Nobuyuki
TAKAHASHI |
| Fukui University Shigeru MORISHIMA |
| Fukui University Takashi KONNO |
| Membrane water transport
is an essential final event not only in the osmotic cell
volume change but also in the following cell volume regulation.
First, we investigated the route of water transport involved
in a regulatory volume decrease (RVD) after osmotic swelling
in human epithelial Intestine 407 cells. Functional expression
of water channel in the cell membrane was supported by the
facts of Pf/Pd >>1 as well as prominent temperature
dependence and mercury sensitivity of Pf. Molecular expression
of AQP3 water channel was confirmed by RT-PCR and immunostaining.
The RVD response was significantly suppressed by mercury
or antisense-induced downregulation of AQP3. Second, an involvement
of water channel in a regulatory volume increase (RVI) after
a secretory volume decrease (SVD) induced by a secretagogue,
carbachol, in human colonic T84 epithelial cells. AQP3 expression
was demonstrated by RT-PCR and immunostaining. Antisense-mediated
knockdown of AQP3 expression abolished SVD and RVI. When
mercury was applied upon the SVD peak, the following RVI
was blocked. Taken together, it is concluded that AQP3 water
channels serve as a prerequisite pathway for volume-regulatory
water transport in human intestinal epithelial cells. |
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