Prolonged signaling at the parathyroid hormone receptor by peptide ligands targeted to a specific receptor conformation
Prolonged signaling at the parathyroid hormone receptor by peptide ligands targeted to a specific receptor conformation
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DOI：
10.1073/pnas.0808750105
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发表时间：
2008-10-28
影响因子：
11.1
通讯作者：
Gardella, Thomas J.
中科院分区：
文献类型：
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作者：
Okazaki, Makoto;Ferrandon, Sebastien;Gardella, Thomas J.
甲状旁腺激素受体（PTHR）是一种B G类蛋白偶联受体，在骨和矿物质离子代谢中起关键作用。配体与PTHR的结合涉及与受体的氨基末端胞外（N）结构域和跨膜/胞外环或跨膜（J）区域的相互作用。最近，我们发现PTH（1-34），而不是PTH相关蛋白，PTHrP（1-36），或M-PTH（1-14），（M = Ala/ Aib（1），Aib（3），Gln（10），Har（11），Ala（12），Trp（14），Arg（19）），以很大程度上GTP γ S-抗性的方式结合PTHR，表明选择性结合新的高亲和力构象（R-0），与GTP γ S-敏感构象（RG）不同。我们研究了在体外和体内引入M取代，这增强了与J结构域的相互作用，到IPTH类似物的C-末端延伸，将参与N结构域相互作用的残基。与PTH（1-34）相比，M-PTH（1-28）和M-PTH（1-34）与R-0的结合亲和力更高，在细胞中产生更持续的cAMP反应，在FRET和亚细胞定位分析中与PTHR形成更稳定的复合物，并且在小鼠中诱导更长时间的钙和磷酸盐反应。此外，在小鼠中每天注射2周后，M-PTH（1-34）诱导的松质骨体积增加和皮质骨转换增加大于PTH（1-34）。因此，推定的R-0 PTHR构象可以与某些PTH配体类似物形成高度稳定的复合物，从而介导骨和/或肾PTH靶细胞中令人惊讶的延长的信号传导应答。通过配体类似物设计来控制PTH配体相对于RG结合R-O的选择性，可以是优化信号传导持续时间的策略，从而优化PTHR激动剂配体的治疗功效。
The parathyroid hormone receptor (PTHR) is a class B G protein-coupled receptor that plays critical roles in bone and mineral ion metabolism. Ligand binding to the PTHR involves interactions to both the amino-terminal extracellular (N) domain, and transmembrane/extracellular loop, or juxtamembrane (J) regions of the receptor. Recently, we found that PTH(1-34), but not PTH-related protein, PTHrP(1-36), or M-PTH(1-14) (M = Ala/ Aib(1),Aib(3),Gln(10),Har(11),Ala(12),Trp(14),Arg(19)), binds to the PTHR in a largely GTP gamma S-resistant fashion, suggesting selective binding to a novel, high-affinity conformation (R-0), distinct from the GTP gamma S-sensitive conformation (RG). We examined the effects in vitro and in vivo of introducing the M substitutions, which enhance interaction to the J domain, into IPTH analogs extended C-terminally to incorporate residues involved in the N domain interaction. As compared with PTH(1-34), M-PTH(1-28) and M-PTH(1-34) bound to R-0 with higher affinity, produced more sustained cAMP responses in cells, formed more stable complexes with the PTHR in FRET and subcellular localization assays, and induced more prolonged calcemic and phosphate responses in mice. Moreover, after 2 weeks of daily injection in mice, M-PTH(1-34) induced larger increases in trabecular bone volume and greater increases in cortical bone turnover, than did PTH(1-34). Thus, the putative R-0 PTHR conformation can form highly stable complexes with certain PTH ligand analogs and thereby mediate surprisingly prolonged signaling responses in bone and/or kidney PTH target cells. Controlling, via ligand analog design, the selectivity with which a PTH ligand binds to R-0, versus RG, may be a strategy for optimizing signaling duration time, and hence therapeutic efficacy, of PTHR agonist ligands.