Herman A, Bignon C, Daniel N, Grosclaude J, Gertler A, Djiane J
Institute of Biochemistry, Food Science and Nutrition, Faculty of Agriculture, The Hebrew University of Jerusalem, Rehovot 76100, Israel.
J Biol Chem. 2000 Mar 3;275(9):6295-301. doi: 10.1074/jbc.275.9.6295.
Although homo- or heterodimerization are common mechanisms for activation of cytokine receptors, cross-talk between two distinct receptors in this superfamily has been never shown. Here we show a physiologically relevant example indicating that such an interaction does occurs, thus raising the hypothesis that heterodimerization between distinct cytokine receptors may be a novel mechanism contributing to the diversity of cytokine signaling. These findings were documented using both surface plasmon resonance and gel filtration experiments and show that ovine placental lactogen (PL) heterodimerizes the extracellular domains (ECDs) of ruminant growth hormone receptor (GHR) and prolactin receptor (PRLR). We also show that PL or PL analogues that exhibit little or no activity in cells transfected with PRLRs and no activity in cells transfected with ovine GHRs exhibit largely enhanced activity in cells cotransfected with both PRLRs and GHRs. Furthermore, chimeric receptors consisting of cytosolic and transmembrane part of ovine GHR or ovine PRLR and ECDs of human granulocyte-macrophage colony-stimulating factor receptor (GM-CSFR) alpha or beta were constructed. Upon transfection into Chinese hamster ovary cells along with reporter luciferase gene and stimulation by GM-CSF, a significant increase in luciferase activity occurred when GM-CSFR-alpha-PRLR and GM-CSFR-beta-GHR or GM-CSFR-alpha-GHR and GM-CSRR-beta-PRLR were cotransfected. In conclusion, we show that ovine PL is capable of functional heterodimerization of GHR and PRLR and that when their cytosolic parts, coupled to the ECD of GM-CSF receptors, are heterodimerized by GM-CSF, they are capable of transducing biological signal.
虽然同二聚化或异二聚化是细胞因子受体激活的常见机制，但该超家族中两个不同受体之间的相互作用从未被证实。在此，我们展示了一个生理相关的例子，表明这种相互作用确实存在，从而提出了一个假设，即不同细胞因子受体之间的异二聚化可能是一种新的机制，有助于细胞因子信号传导的多样性。这些发现通过表面等离子体共振和凝胶过滤实验得到了证实，结果表明，绵羊胎盘催乳素（PL）使反刍动物生长激素受体（GHR）和催乳素受体（PRLR）的细胞外结构域（ECD）发生异二聚化。我们还发现，PL或PL类似物在转染了PRLR的细胞中几乎没有活性，在转染了绵羊GHR的细胞中没有活性，但在同时转染了PRLR和GHR的细胞中活性大大增强。此外，构建了由绵羊GHR或绵羊PRLR的胞质和跨膜部分与人粒细胞-巨噬细胞集落刺激因子受体（GM-CSFR）α或β的ECD组成的嵌合受体。将其与报告荧光素酶基因一起转染到中国仓鼠卵巢细胞中，并经GM-CSF刺激后，当GM-CSFR-α-PRLR和GM-CSFR-β-GHR或GM-CSFR-α-GHR和GM-CSRR-β-PRLR共转染时，荧光素酶活性显著增加。总之，我们证明了绵羊PL能够使GHR和PRLR发生功能性异二聚化，并且当它们与GM-CSF受体ECD偶联的胞质部分被GM-CSF异二聚化时，能够转导生物信号。
