Osmoregulated taurine transport in H4IIE hepatoma cells and perfused rat liver.
Osmoregulated taurine transport in H4IIE hepatoma cells and perfused rat liver.
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H4IIE 肝癌细胞和灌注大鼠肝脏中的渗透调节牛磺酸转运。
DOI：
10.1042/bj3210683
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发表时间：
1997
期刊：
影响因子：
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通讯作者：
D. Häussinger
中科院分区：
文献类型：
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作者：
U. Warskulat;M. Wettstein;D. Häussinger
研究了异渗透暴露对H4IIE大鼠肝癌细胞中牛磺酸转运的影响。高渗透（405 mosmol/l）暴露于H4IIE细胞刺激Na+依赖性牛磺酸摄取并导致牛磺酸转运蛋白（TAUT） mRNA水平增加，而低渗透（205 mosmol/l）暴露与正常渗透（305 mosmol/l）对照孵育相比，牛磺酸摄取和TAUT mRNA水平均降低。当环境渗透压从205 momol /l提高到405 momol /l时，牛磺酸的摄取增加了30-40倍。当H4IIE细胞和灌注的肝脏预先加载牛磺酸时，低渗透细胞肿胀导致牛磺酸从细胞中快速释放。牛磺酸外排对4,4'-二异硫氰酸二苯乙烯-2,2'-二磺酸（DIDS）敏感，但对牛磺酸摄取不敏感，这表明DIDS敏感通道参与了介导容量调节性牛磺酸外排。然而，在H4IIE大鼠肝癌细胞和原代肝细胞中，TAUT mRNA水平强烈依赖于环境渗透压，而其他渗透压转运蛋白的mRNA，即甜菜碱转运蛋白BGT-1和Na+/肌醇转运蛋白SMIT，则未检测到。与此一致的是，H4IIE肝癌细胞的肌醇摄取很低，并且不受高渗透压的刺激。然而，尽管缺乏BGT-1 mRNA，但观察到甜菜碱的轻微渗透敏感摄取，但其速率不到牛磺酸运输的10%。本研究确定了H4IIE细胞中组成性表达和渗透敏感的TAUT，并使用牛磺酸作为主要的渗透物，而甜菜碱和肌醇在这些细胞的渗透策略中起很少或没有作用。这与大鼠肝巨噬细胞形成对比，其中甜菜碱已被证明是主要的渗透物。
The effects of aniso-osmotic exposure on taurine transport were studied in H4IIE rat hepatoma cells. Hyperosmotic (405 mosmol/l) exposure of H4IIE cells stimulated Na+-dependent taurine uptake and led to an increase in taurine transporter (TAUT) mRNA levels, whereas hypo-osmotic (205 mosmol/l) exposure diminished both taurine uptake and TAUT mRNA levels when compared with normo-osmotic (305 mosmol/l) control incubations. Taurine uptake increased 30-40-fold upon raising the ambient osmolarity from 205 to 405 mosmol/l. When H4IIE cells and perfused livers were preloaded with taurine, hypo-osmotic cell swelling led to a rapid release of taurine from the cells. The taurine efflux, but not taurine uptake, was sensitive to 4,4'-di-isothiocyanatostilbene-2,2'-disulphonic acid (DIDS), suggestive of an involvement of DIDS-sensitive channels in mediating volume-regulatory taurine efflux. Whereas in both H4IIE rat hepatoma cells and primary hepatocytes TAUT mRNA levels were strongly dependent upon ambient osmolarity, mRNAs for other osmolyte transporters, i.e. the betaine transporter BGT-1 and the Na+/myo-inositol transporter SMIT, were not detectable. In line with this, myo-inositol uptake by H4IIE hepatoma cells was low and was not stimulated by hyperosmolarity. However, despite the absence of BGT-1 mRNA, a slight osmosensitive uptake of betaine was observed, but the rate was less than 10% of that of taurine transport. This study identifies a constitutively expressed and osmosensitive TAUT in H4IIE cells and the use of taurine as a main osmolyte, whereas betaine and myo-inositol play little or no role in the osmolyte strategy in these cells. This is in contrast with rat liver macrophages, in which betaine has been shown to be a major osmolyte.