A cell surface inactive mutant of the human lutropin receptor (hLHR) attenuates signaling of wild-type or constitutively active receptors via heterodimerization.
A cell surface inactive mutant of the human lutropin receptor (hLHR) attenuates signaling of wild-type or constitutively active receptors via heterodimerization.
复制标题
人促黄体素受体 (hLHR) 的细胞表面失活突变体通过异二聚化减弱野生型或组成型活性受体的信号传导。
DOI：
10.1016/j.cellsig.2009.07.003
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发表时间：
2009
影响因子：
4.8
通讯作者：
Segaloff,DeborahL
中科院分区：
文献类型：
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作者：
Zhang,Meilin;Feng,Xiuyan;Guan,Rongbin;Hébert,TerenceE;Segaloff,DeborahL
人促黄体激素受体（hLHR）的D405 N和Y 546 F突变先前已显示部分减弱hCG刺激的cAMP合成，尽管细胞表面表达和hCG结合亲和力正常（Min，L.和Ascoli，M.摩尔年. 14：1797-1810，2000）。我们现在表明，这些突变各自稳定了hLHR的静息状态。组合突变体D405 N、Y 546 F在细胞表面类似地表达，并表现出正常的配体结合，但严重的信号传导受损。将hLHR（wt）引入稳定表达信号传导失活的D405 N、Y 546 F的细胞中导致hLHR（wt）减弱hCG刺激的cAMP产生，即使共表达过量的Gs。类似地，D405 N、Y 546 F与hLHR组成型活性突变体（CAM）的共表达减弱了它们的组成型活性。定量生物发光共振能量转移（BRET）分析表明D405 N、Y 546 F与wt和CAM hLHR形成异二聚体。相反，hLHR（D405 N，Y 546 F）不与黑皮质素3受体（MC 3R）异二聚化，并且当这两种受体共表达时，通过MC 3R的激动剂刺激的cAMP产生不减弱。总之，我们的数据表明，信号传导失活的hLHR突变体（通常被运输到质膜）减弱了细胞表面定位的野生型或组成型活性的hLHR由于受体异源二聚化的信号传导。因此，我们的研究表明，一种新的衍生物的GPCR信号产生的受体二聚化。
The D405N and Y546F mutations of the human lutropin receptor (hLHR) have previously been shown to partially attenuate hCG-stimulated cAMP synthesis despite normal cell surface expression and hCG binding affinity (Min, L. and Ascoli, M. Mol. Endocrinol. 14:1797–1810, 2000). We now show that these mutations each stabilize a resting state of the hLHR. A combined mutant D405N,Y546F is similarly expressed at the cell surface and exhibits normal ligand-binding, but is profoundly signaling impaired. Introduction of hLHR(wt) into cells stably expressing the signaling inactive D405N,Y546F resulted in the attenuation of hCG-stimulated cAMP production by hLHR(wt) even if excess Gs is co-expressed. Similarly, co-expression of D405N,Y546F with hLHR constitutively active mutants (CAMs) attenuated their constitutive activity. Quantitative bioluminescence resonance energy transfer (BRET) analyses demonstrated that D405N,Y546F formed heterodimers with both wt and CAM hLHR. In contrast hLHR(D405N,Y546F) did not heterodimerize with the melanocortin 3 receptor (MC3R) and agonist-stimulated cAMP production through the MC3R was not attenuated when these two receptors were co-expressed. Taken altogether, our data demonstrate that a signaling inactive hLHR mutant (that is trafficked normally to the plasma membrane) attenuates the signaling of the cell surface localized wt or the constitutively active hLHR due to receptor heterodimerization. Our studies, therefore, suggest a novel ramification of GPCR signaling resulting from receptor dimerization.