Differential expression of TRPM7 in rat hepatoma and embryonic and adult hepatocytes
Differential expression of TRPM7 in rat hepatoma and embryonic and adult hepatocytes
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DOI：
10.1139/y11-136
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发表时间：
2012-04-01
影响因子：
2.1
通讯作者：
Hill, Ceredwyn E.
中科院分区：
文献类型：
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作者：
Lam, D. Hung;Grant, Caroline E.;Hill, Ceredwyn E.
TRPM7通道与细胞的存活、增殖和分化有关。然而，从胚胎到终末分化状态的特定细胞类型中TRPM7活性的分布尚未确定。在这里，我们研究了TRPM7在不同发育阶段的大鼠肝细胞中的表达。利用全细胞膜片钳技术，在RLC-18细胞中发现了TRPM7样钠电流。RLC-18细胞是一种分化、增殖的肝细胞系，来源于第17天的胚胎大鼠肝脏。电流是外向整流的，在无二价溶液中增强，并被细胞内镁离子抑制。逆转录聚合酶链式反应(RT-PCR)显示RLC-18细胞同时表达TRPM6和TRPM7。然而，1 mmo1/L的2-氨基乙氧基苯基硼酸酯(2-APB)可使RLC-18细胞的平均电流降低近80%，并被取消，表明TRPM7是RLC-18细胞的主要电流载体。功能比较显示，相对于终末分化的成年大鼠肝细胞，RLC-18和WIF-B细胞的电流分别高出1.8倍和3.9倍。我们的结果表明，质膜TRPM7通道在增殖细胞中的表达高于终末分化和未分化的大鼠肝细胞，提示该通道的下调与肝细胞的分化有关。
TRPM7 channels are implicated in cellular survival, proliferation, and differentiation. However, a profile of TRPM7 activity in a specific cell type has not been determined from embryonic to terminally differentiated state. Here, we characterized TRPM7 expression in a spectrum of rat liver cells at different developmental stages. Using the whole-cell patch clamp technique, TRPM7-like Na+ currents were identified in RLC-18 cells, a differentiated, proliferating hepatocellular line derived from day 17 embryonic rat liver. Currents were outwardly rectifying, enhanced in divalent-free solutions, and inhibited by intracellular Mg2+. Reverse transcription - polymerase chain reaction (RT-PCR) revealed that RLC-18 cells express both TRPM6 and TRPM7. However, mean currents were reduced almost 80% by 1 mmol/L 2-aminoethoxyphenylborate (2-APB) and were abolished in RLC-18 cells heterologously expressing a dominant negative TRPM7 construct, suggesting that TRPM7 is the major current carrier in these cells. Functional comparison showed that relative to terminally differentiated adult rat hepatocytes, currents were 1.8 and 3.9 times higher in, respectively, RLC-18 and WIF-B cells, a rat hepatoma - human fibroblast cross. Our results demonstrate that plasma membrane TRPM7 channels are more highly expressed in proliferating cells as compared with terminally differentiated and nondividing rat hepatocytes and suggest that downregulation of this channel is associated with hepatocellular differentiation.