Lanthanides potentiate TRPC5 currents by an action at extracellular sites close to the pore mouth
Lanthanides potentiate TRPC5 currents by an action at extracellular sites close to the pore mouth
复制标题
DOI：
10.1074/jbc.m211484200
复制
发表时间：
2003-02-07
影响因子：
4.8
通讯作者：
Plant, TD
中科院分区：
文献类型：
--
作者：
Jung, S;Mühle, A;Plant, TD
经典瞬时受体电位通道（TRPC）亚家族（TRPC 1 -7）的哺乳动物成员是参与受体介导的细胞内Ca 2+增加的Ca 2+可渗透阳离子通道。与大多数其他TRP相关通道不同，这些通道被La 3+和Gd 3+抑制，通过TRPC 4和TRPC 5的电流被La 3+增强。由于这些不同的镧系元素对TRPC亚型的影响可能是有用的澄清不同的TRPC在天然组织中的作用，我们的特点是增强效应的详细和本地化的分子决定因素的增强诱变。通过TRPC 5的全细胞电流被微摩尔浓度的La 3+或Gd 3+可逆地增强，而毫摩尔浓度是抑制性的。相比之下，TRPC 6在微摩尔浓度下被La 3+或Gd 3+以类似的程度阻断，并且没有表现出增强作用。镧系元素对TRPC 5的双重作用也在外向斑片中观察到。即使在微摩尔浓度下，单通道电导降低镧3+，但电导的减少伴随着通道开放概率的急剧增加，导致更大的积分电流。位于通道孔的细胞外口附近的带负电荷的氨基酸Glu（543）和Glu（595）/Glu（598）的中和导致增强作用的丧失，并且Glu（595）/Glu（598）导致通道抑制的改变。我们的结论是，在微摩尔范围内，镧系离子La 3+和Gd 3+有相反的影响，通过TRPC 5和TRPC 6通道的全细胞电流。TRPC 4和TRPC 5的增效微摩尔镧+在细胞外的网站接近孔口是一个很有前途的工具，用于确定这些亚型参与受体操作的阳离子电导的天然细胞。
Mammalian members of the classical transient receptor potential channel (TRPC) subfamily (TRPC1-7) are Ca2+-permeable cation channels involved in receptor-mediated increases in intracellular Ca2+. Unlike most other TRP-related channels, which are inhibited by La3+ and Gd3+, currents through TRPC4 and TRPC5 are potentiated by La3+. Because these differential effects of lanthanides on TRPC subtypes may be useful for clarifying the role of different TRPCs in native tissues, we characterized the potentiating effect in detail and localized the molecular determinants of potentiation by mutagenesis. Whole cell currents through TRPC5 were reversibly potentiated by micromolar concentrations of La3+ or Gd3+, whereas millimolar concentrations were inhibitory. By comparison, TRPC6 was blocked to a similar extent by La3+ or Gd3+ at micromolar concentrations and showed no potentiation. Dual effects of lanthanides on TRPC5 were also observed in outside-out patches. Even at micromolar concentrations, the single channel conductance was reduced by La3+, but reduction in conductance was accompanied by a dramatic increase in channel open probability, leading to larger integral currents. Neutralization of the negatively charged amino acids Glu(543) and Glu(595)/Glu(598), situated close to the extracellular mouth of the channel pore, resulted in a loss of potentiation, and, for Glu(595)/Glu(598) in a modification of channel inhibition. We conclude that in the micromolar range, the lanthanide ions La3+ and Gd3+ have opposite effects on whole cell currents through TRPC5 and TRPC6 channels. The potentiation of TRPC4 and TRPC5 by micromolar La3+ at extracellular sites close to the pore mouth is a promising tool for identifying the involvement of these isoforms in receptor-operated cation conductances of native cells.