Dimerization of the Sodium/Iodide Symporter.
Dimerization of the Sodium/Iodide Symporter.
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钠/碘同向转运体的二聚化。
DOI：
10.1089/thy.2019.0034
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发表时间：
2019
期刊：
影响因子：
--
通讯作者：
Thompson RJ
中科院分区：
文献类型：
--
作者：
Thompson RJ
背景：甲状腺滤泡上皮细胞通过钠/碘同向转运体（NIS）积累碘的能力被用于成功治疗大多数甲状腺癌，尽管一部分患者丧失了功能性NIS活性，对放射性碘治疗无反应，临床结局较差。然而，我们对NIS监管的了解仍然有限。虽然许多膜蛋白通过二聚化进行功能调节，但NIS二聚化的确切证据很少，并且这是否可能影响放射性碘摄取和治疗成功完全未知。我们假设，NIS的二聚化和二聚化是碘uptake.Methods的先决条件：免疫共沉淀，邻近连接，和Förster共振能量转移（FRET）测定被用来评估NIS：NIS相互作用。结果：通过3种不同的方法证实了细胞内存在大量的NIS二聚体。FRET和邻近连接试验表明，虽然NIS可以作为二聚体存在于质膜（PM），但在其他细胞区室中也很明显。同源性建模揭示了二聚体相互作用的一个关键潜在位点，其中6个残基相距<30 μ m。特别地，NIS残基Y242、T243和Q471被鉴定为对二聚化至关重要。残基Y242和T243的个体突变使NIS无功能，而Q471的废除不影响放射性碘摄取。FRET数据表明，假定的二聚化接口可以容忍的损失，但不是两个，这三个集群residues.Conclusions：我们第一次表明，NIS dimerizesin体外，我们确定的关键残基通过这种情况发生。我们假设NIS的二聚化对其向PM的运输至关重要，因此可能代表了一种新的机制，需要考虑克服甲状腺癌患者的治疗失败。
Background:The ability of thyroid follicular epithelial cells to accumulate iodide via the sodium/iodide symporter (NIS) is exploited to successfully treat most thyroid cancers, although a subset of patients lose functional NIS activity and become unresponsive to radioiodide therapy, with poor clinical outcome. Our knowledge of NIS regulation remains limited, however. While numerous membrane proteins are functionally regulated via dimerization, there is little definitive evidence of NIS dimerization, and whether this might impact upon radioiodide uptake and treatment success is entirely unknown. We hypothesized that NIS dimerizes and that dimerization is a prerequisite for iodide uptake.Methods:Coimmunoprecipitation, proximity ligation, and Förster resonance energy transfer (FRET) assays were used to assess NIS:NIS interaction. To identify residues involved in dimerization, a homology model of NIS structure was built based on the crystal structure of the dimeric bacterial protein vSGLT.Results:Abundant cellular NIS dimerization was confirmedin vitrovia three discrete methodologies. FRET and proximity ligation assays demonstrated that while NIS can exist as a dimer at the plasma membrane (PM), it is also apparent in other cellular compartments. Homology modeling revealed one key potential site of dimeric interaction, with six residues <3Å apart. In particular, NIS residues Y242, T243, and Q471 were identified as critical to dimerization. Individual mutation of residues Y242 and T243 rendered NIS nonfunctional, while abrogation of Q471 did not impact radioiodide uptake. FRET data show that the putative dimerization interface can tolerate the loss of one, but not two, of these three clustered residues.Conclusions:We show for the first time that NIS dimerizesin vitro, and we identify the key residues via which this happens. We hypothesize that dimerization of NIS is critical to its trafficking to the PM and may therefore represent a new mechanism that would need to be considered in overcoming therapeutic failure in patients with thyroid cancer.