Bernard Jérôme, Harb Catherine, Mortier Erwan, Quéméner Agnès, Meloen Rob H, Vermot-Desroches Claudine, Wijdeness John, van Dijken Peter, Grötzinger Joachim, Slootstra Jerry W, Plet Ariane, Jacques Yannick
Groupe de Recherche Cytokines et Récepteurs, Unité INSERM 601, Institut de Biologie, 9 Quai Moncousu, 44093 Nantes Cedex 01, France.
J Biol Chem. 2004 Jun 4;279(23):24313-22. doi: 10.1074/jbc.M312458200. Epub 2004 Mar 23.
To identify the epitopes in human interleukin-15 (IL-15) that are responsible for binding to the interleukin-15 receptor alpha chain, antibody and receptor mapping by peptide scanning and site-directed mutagenesis was used. By using peptide scanning, we identified four regions in IL-15. The first region ((85)CKECEELEEKN(95)) is located in the C-D loop and is recognized by a set of non-inhibitory antibodies. The second region ((102)SFVHIVQMFIN(112)) is located in helix D and is recognized by two antibodies that are inhibitory of IL-15 bio-activity but not of IL-15 binding to IL-15Ralpha. The two remaining regions react with a recombinant soluble form of the IL-15Ralpha; the first ((44)LLELQVISL(52), peptide 1) corresponds to a sequence located in the B-helix and the second ((64)ENLII(68), peptide 2) to a sequence located in helix C. The latter is also contained in the epitope recognized by an antibody (monoclonal antibody B-E29) that prevents IL-15 binding to IL-15Ralpha. By site-directed mutagenesis, we confirmed that residues present in peptide 1 (Leu-45, Glu-46, Val-49, Ser-51, and Leu-52) and peptide 2 (Leu-66 and Ile-67) are involved in the binding of IL-15 to IL-15Ralpha. Furthermore, the results presented indicate that residues in the second peptide (Glu-64, Asn-65, and Ile-68) participate in IL-2Rbeta recruitment. This finding could have implications for the dynamics of receptor assembly. These results also indicate that the modes of interaction of IL-15 and IL-2 with their respective alpha chains are not completely analogous. Finally, some of the IL-15 mutants generated in this study displayed agonist or antagonist properties and may be useful as therapeutic agents.
为了鉴定人白细胞介素15（IL-15）中负责与白细胞介素15受体α链结合的表位，采用了通过肽扫描和定点诱变进行抗体和受体图谱分析的方法。通过肽扫描，我们在IL-15中鉴定出四个区域。第一个区域（(85)CKECEELEEKN(95)）位于C-D环，可被一组非抑制性抗体识别。第二个区域（(102)SFVHIVQMFIN(112)）位于螺旋D，可被两种抑制IL-15生物活性但不抑制IL-15与IL-15Rα结合的抗体识别。其余两个区域与重组可溶性形式的IL-15Rα反应；第一个区域（(44)LLELQVISL(52)，肽1）对应于位于B螺旋的序列，第二个区域（(64)ENLII(68)，肽2）对应于位于螺旋C的序列。后者也包含在一种阻止IL-15与IL-15Rα结合的抗体（单克隆抗体B-E29）识别的表位中。通过定点诱变，我们证实肽1（Leu-45、Glu-46、Val-49、Ser-51和Leu-52）和肽2（Leu-66和Ile-67）中的残基参与IL-15与IL-15Rα的结合。此外，所呈现的结果表明第二个肽中的残基（Glu-64、Asn-65和Ile-68）参与IL-2Rβ的募集。这一发现可能对受体组装的动力学有影响。这些结果还表明IL-15和IL-2与其各自α链的相互作用模式并不完全相似。最后，本研究中产生的一些IL-15突变体表现出激动剂或拮抗剂特性，可能作为治疗剂有用。
