Ligand functional selectivity in EphA2 receptor signaling

总结 “配体功能选择性”现象背后的机制，定义为配体的功能选择性的能力。 不同的配体，通过共同的 受体，不理解为受体酪氨酸激酶。在这里，我们寻求获得这样的 EphA 2是一种跨膜受体酪氨酸激酶， 对人类健康很重要。我们将研究EphA 2对三种配体的信号传导反应： 二聚体肝配蛋白A1-Fc、单体m-肝配蛋白A1和工程化单体YSA肽 在活细胞的背景下，使用生物化学和生物物理方法来研究配体。我们有 已经发现EphA 2/YSA、EphA 2/m- 活细胞中的ephrinA 1和EphA 2/ephrinA 1-Fc寡聚体，在目标1中我们将研究 这些差异是否通过质膜传递， 在EphA 2细胞内区域的构型中。在目标2中，我们将比较EphA 2 对三种配体的信号应答，以检验下游信号应答的差异 信号传导与一些EphA 2酪氨酸的差异磷酸化相关，和/或 EphA 2活化/失活的不同动力学。这项工作将促进一般 了解受体酪氨酸激酶信号转导，并告知设计 具有改进的特异性和安全性的“路径偏向”靶向药物。

SUMMARY The mechanism behind the phenomenon of "ligand functional selectivity”, defined as the ability of different ligands to differentially activate distinct signaling pathways through a common receptor, is not understood for receptor tyrosine kinases. Here we seek to obtain such mechanistic information for EphA2, a transmembrane receptor tyrosine kinase that is critically important for human health. We will investigate EphA2 signaling responses to three ligands: dimeric ephrinA1-Fc, monomeric m-ephrinA1, and the engineered monomeric YSA peptide ligand using biochemical and biophysical approaches in the context of live cells. We have already discovered differences in the extracellular configuration of the EphA2/YSA, EphA2/m- ephrinA1 and EphA2/ephrinA1-Fc oligomers in live cells, and in Aim 1 we will investigate whether these differences are transmitted across the plasma membrane, leading to differences in the configuration of the EphA2 intracellular regions. In Aim 2, we will compare EphA2 signaling responses to the three ligands to test the hypothesis that differences in downstream signaling correlate with differential phosphorylation of some of the EphA2 tyrosines and/or different kinetics of EphA2 activation/inactivation. This work will advance the general understanding of receptor tyrosine kinase signal transduction, and inform the design of “pathway-biased” targeted drugs with improved specificity and safety profiles.