Regulation of Receptor Signaling by Relaxin A Chain Motifs DERIVATION OF PAN-SPECIFIC AND LGR7-SPECIFIC HUMAN RELAXIN ANALOGS
Regulation of Receptor Signaling by Relaxin A Chain Motifs DERIVATION OF PAN-SPECIFIC AND LGR7-SPECIFIC HUMAN RELAXIN ANALOGS
复制标题
DOI：
10.1074/jbc.m806817200
复制
发表时间：
2008-11-14
影响因子：
4.8
通讯作者：
Hsu, Sheau Yu Teddy
中科院分区：
文献类型：
--
作者：
Park, Jae-Il;Semyonov, Jenia;Hsu, Sheau Yu Teddy
松弛素肽是调节妊娠期生殖组织重塑和肾心血管系统的重要激素。最近的研究表明，七种人松弛素家族肽中的两种，松弛素H2（RLN 2）和INSL 3，仅通过富含亮氨酸的重复序列的G蛋白偶联受体，LGR 7和LGR 8进行信号传导。尽管已充分表征了RLN 2 B链上的RXXXRXXI基序赋予受体活化活性，但不清楚RLN 2 A链在受体相互作用中起什么作用。模型四足动物同线区松弛素家族基因的分析表明，RLN 2直系同源物的A链表现出更大的序列差异相比，含有受体结合结构域的B链，预示着在受体相互作用的潜在作用，因此，在这个快速发展的肽激素定义受体的选择性。为了验证我们的假设，即人RLN 2 A链中的选择残基在受体相互作用中起关键作用，我们研究了A链中具有残基取代的突变肽。在这里，我们表明A16和A17位置的丙氨酸取代增强了RLN 2的LGR 8激活活性，而A22-23区域（RLN 2（A22-23））的突变消除了LGR 8激活活性，但不消除LGR 7激活活性。此外，我们证明了RLN 2（A22-23）突变体的功能特性主要归因于Phe（A23）位置的修饰。综上所述，我们的研究表明，Thr（A16），Lys（A17），和Phe（A23）构成人RLN 2的受体结合界面的一部分，这些残基的修饰导致了新的人RLN 2类似物的产生，这将允许在体内选择性激活人LGR 7，而不是LGR 8。
Relaxin peptides are important hormones for the regulation of reproductive tissue remodeling and the renal cardiovascular system during pregnancy. Recent studies demonstrated that two of the seven human relaxin family peptides, relaxin H2 (RLN2) and INSL3, signal exclusively through leucine-rich repeat-containing G protein-coupled receptors, LGR7 and LGR8. Although it was well characterized that an RXXXRXXI motif at the RLN2 B chain confers receptor activation activity, it is not clear what roles RLN2 A chain plays in receptor interaction. Analyses of relaxin family genes on syntenic regions of model tetrapods showed that the A chain of RLN2 orthologs exhibited a greater sequence divergence as compared with the receptor-binding domain-containing B chain, foreshadowing a potential role in receptor interactions; hence, defining receptor selectivity in this fast evolving peptide hormone. To test our hypothesis that select residues in the human RLN2 A chain play key roles in receptor interaction, we studied mutant peptides with residue substitution(s) in the A chain. Here, we showed that alanine substitution at the A16 and A17 positions enhances LGR8-activation activity of RLN2, whereas mutation at the A22-23 region (RLN2(A22-23)) ablates LGR8, but not LGR7, activation activity. In addition, we demonstrated that the functional characteristics of the RLN2(A22-23) mutant are mainly attributed to modifications at the Phe(A23) position. Taken together, our studies indicated that Thr(A16), Lys(A17), and Phe(A23) constitute part of the receptor-binding interface of human RLN2, and that modification of these residues has led to the generation of novel human RLN2 analogs that would allow selective activation of human LGR7, but not LGR8, in vivo.