Residues 155 and 348 Contribute to the Determination of P2X7 Receptor Function via Distinct Mechanisms Revealed by Single-nucleotide Polymorphisms
Residues 155 and 348 Contribute to the Determination of P2X7 Receptor Function via Distinct Mechanisms Revealed by Single-nucleotide Polymorphisms
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DOI：
10.1074/jbc.m110.211284
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发表时间：
2011-03-11
影响因子：
4.8
通讯作者：
Jiang, Lin-Hua
中科院分区：
文献类型：
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作者：
Bradley, Helen J.;Baldwin, Jocelyn M.;Jiang, Lin-Hua
P2 X（7）受体在介导细胞外ATP的生理功能中是重要的，并且改变的受体表达和功能在疾病发病机制中具有致病作用。在这里，我们通过跟踪两个人类单核苷酸多态性（SNP）突变来研究决定P2 X（7）受体功能的机制，这两个突变将人类（h）P2 X（7）受体中的His-155和Ala-348替换为大鼠（r）P2 X（7）受体中的相应残基Tyr-155和Thr-348。hP 2X（7）受体的H155 Y和A348 T突变增加ATP诱导的电流，而rP 2X（7）受体的Y155 H和T348 A突变则引起相反的效应。这种功能开关是一个令人信服的迹象，这些残基是关键的P2 X（7）受体功能。hP 2X（7）受体中His-155和Ala-348对具有不同侧链的残基的额外突变揭示了对侧链性质的不同依赖性，支持这两个残基的特异性。用rP 2X（7）受体中的等效残基取代hP 2X（7）受体中His-155和Ala-348周围的残基也影响ATP诱导电流，但不能完全使人联想到H155 Y和A348 T效应。免疫荧光成像和生物素标记分析显示，hP 2X（7）受体中的H155 Y增加，rP 2X（7）受体中的Y155 H减少细胞表面表达。这种对比效应在残基348的相互突变中不明显。综上所述，我们的结果表明，在位置155和348的残基有助于P2 X（7）受体的功能，通过确定表面表达和单通道功能，分别。这种解释与hP 2X（7）受体结构模型中残基的位置一致。
P2X(7) receptors are important in mediating the physiological functions of extracellular ATP, and altered receptor expression and function have a causative role in the disease pathogenesis. Here, we investigated the mechanisms determining the P2X(7) receptor function by following two human single-nucleotide polymorphism (SNP) mutations that replace His-155 and Ala-348 in the human (h) P2X(7) receptor with the corresponding residues, Tyr-155 and Thr-348, in the rat (r) P2X(7) receptor. H155Y and A348T mutations in the hP2X(7) receptor increased ATP-induced currents, whereas the reciprocal mutations, Y155H and T348A, in the rP2X(7) receptor caused the opposite effects. Such a functional switch is a compelling indication that these residues are critical for P2X(7) receptor function. Additional mutations of His-155 and Ala-348 in the hP2X(7) receptor to residues with diverse side chains revealed a different dependence on the side chain properties, supporting the specificity of these two residues. Substitutions of the residues surrounding His-155 and Ala-348 in the hP2X(7) receptor with the equivalent ones in the rP2X(7) receptor also affected ATP-induced currents but were not fully reminiscent of the H155Y and A348T effects. Immunofluorescence imaging and biotin labeling assays showed that H155Y in the hP2X(7) receptor increased and Y155H in the rP2X(7) receptor decreased cell-surface expression. Such contrasting effects were not obvious with the reciprocal mutations of residue 348. Taken together, our results suggest that residues at positions 155 and 348 contribute to P2X(7) receptor function via determining the surface expression and the single-channel function, respectively. Such interpretations are consistent with the locations of the residues in the structural model of the hP2X(7) receptor.