Mechanisms of Cross-talk Between EphrinB and Alternate Signaling Pathways

EphrinB 与替代信号通路之间的串扰机制

• 批准号: 8763043
• 负责人: Ira Daar
• 金额: $ 67.34万
• 依托单位: DIVISION OF BASIC SCIENCES - NCI
• 依托单位国家: 美国
• 资助国家: 美国
• 起止时间: 至
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/8763043
• 关键词: Adhesions; Affect; Axon; Benign; Binding; Biological Models; Breast; Cancer cell line; Cell Cycle Progression; Cell Polarity; Cell-Cell Adhesion; Cell-Matrix Junction; Cells; Colon; Complex; Congenital Abnormality; Cytoplasmic Tail; Development; Embryo; Embryonic Development; Eph Family Receptors; Ephrins; Epithelial Cells; Event; Fibroblast Growth Factor; Fibroblast Growth Factor Receptors; Frequencies; Human; Intercellular Junctions; Laboratories; Ligand Binding; Ligands; Link; Malignant Neoplasms; Malignant neoplasm of gastrointestinal tract; Mediating; Mediator of activation protein; Membrane; Modification; Movement; Neoplasm Metastasis; Neural Crest Cell; Neuroblastoma; Pathway interactions; Pattern; Phenotype; Phosphorylation; Play; Positioning Attribute; Process; Prostate; Protein Tyrosine Kinase; Proteins; Repression; Research; Retinal; Role; Scaffolding Protein; Signal Pathway; Signal Transduction; Signaling Molecule; Staging; Stem cells; System; Tight Junctions; Tissues; Tumor Angiogenesis; Tumor Cell Invasion; Tumor Stem Cells; Tyrosine Phosphorylation; Vertebrates; Visual Fields; Xenopus; angiogenesis; cell motility; embryonic stem cell; epithelial to mesenchymal transition; gain of function; hindbrain; human disease; in vivo; insight; lung small cell carcinoma; melanoma; member; migration; neoplastic cell; pluripotency; protein complex; retinal progenitor cell; skeletal; stem cell fate specification; tumor; tumorigenesis

During normal development progenitor cells of many tissues undergo progressive restriction of pluripotency, epithelial-to-mesenchymal transition, proliferation, migration, and differentiation. Most, if not all, of these events involve modifications of cell-cell and cell-matrix adhesion, and abnormal modifications of these adhesion systems are often associated with the formation of tumors. The Eph family of receptor tyrosine kinases and their ligands, the ephrins, are frequently over-expressed in a wide variety of cancers, including breast, small-cell lung and gastrointestinal cancers, melanomas, and neuroblastomas. Using the Xenopus embryonic system, we have demonstrated that signaling mediated by the intracellular domain of ephrinB affects cell-cell adhesion, and that this activity can be modulated by interaction with an activated FGF receptor. The transmembrane ephrinB1 protein is a bi-directional signaling molecule that signals through its cytoplasmic domain to promote cellular movements into the eye field, whereas activation of the fibroblast growth factor receptor (FGFR) represses these movements and retinal fate. In Xenopus embryos, ephrinB1 plays a role in retinal progenitor cell movement into the eye field through an interaction with the scaffold protein Dishevelled (Dsh). However, the mechanism by which the FGFR may regulate this cell movement is unknown. Here we present evidence that FGFR-induced repression of retinal fate is dependent upon phosphorylation within the intracellular domain of ephrinB1. We demonstrate that phosphorylation of tyrosines 324 and 325 within ephrinB1 disrupts the ephrinB1/Dsh interaction, thus modulating retinal progenitor movement that is dependent on the planar cell polarity (PCP) pathway. These results provide mechanistic insight into how FGF signaling modulates ephrinB1 control of retinal progenitor movement within the eye field. Moreover, we found evidence that ephrinB1 signaling may regulate cell-cell junctions through a cell polarity complex in vivo. This study focused on assessing whether ephrinB1 is a mediator or modulator of cell-cell junction signaling in epithelial cells using the Xenopus system. We presented evidence that the Par polarity complex protein, Par-6, which is a major scaffold protein required for establishing tight junctions, associates with ephrinB1 and is regulated by ephrinB1, resulting in the control of tight junctions. Using the epithelial cells of early stage Xenopus embryos, we showed that loss- or gain-of function of ephrinB1 can disrupt cell-cell contacts and tight junctions. This study reveals a mechanism where ephrinB1 competes with active Cdc42 for binding to Par-6, a scaffold protein central to the Par polarity complex (Par-3/Par-6/Cdc42/aPKC) and disrupts the localization of tight junction-associated proteins (ZO-1, Cingulin). This competition affects formation of tight junctions, and is regulated by tyrosine phosphorylation of ephrinB1.

在正常发育期间，许多组织的祖细胞经历了多能性，上皮到间质转变，增殖，迁移和分化的进行性限制。这些事件中的大多数（如果不是全部）涉及细胞 - 细胞和细胞垫粘附的修饰，并且这些粘附系统的异常修饰通常与肿瘤的形成有关。 EPH的受体酪氨酸激酶及其配体的eph家族（ephrins）经常在各种各样的癌症中过度表达，包括乳腺癌，小细胞肺和胃肠道癌，黑素瘤和神经母细胞瘤。使用Xenopus胚胎系统，我们证明了由Ephrinb的细胞内结构域介导的信号会影响细胞细胞粘附，并且可以通过与活化的FGF受体相互作用来调节该活性。跨膜埃菲林B1蛋白是一种双向信号分子，它通过其细胞质结构域发信号，以促进细胞运动进入眼科，而成纤维细胞生长因子受体（FGFR）的激活会抑制这些运动和视网膜命运。在Xenopus胚胎中，Ephrinb1通过与脚手架蛋白质味道（DSH）的相互作用在视网膜祖细胞进入眼场中起作用。但是，FGFR可能调节该细胞运动的机制尚不清楚。在这里，我们提供了证据表明，FGFR诱导的视网膜命运的抑制取决于Ephrinb1的细胞内结构域内的磷酸化。我们证明，埃菲林贝1中酪氨酸324和325的磷酸化破坏了ephrinb1/dsh的相互作用，因此调节了视网膜祖细胞运动，该视网膜祖细胞运动取决于平面细胞极性（PCP）途径。这些结果提供了有关FGF信号传导如何调节眼场视网膜祖细胞运动的控制。此外，我们发现证据表明ephrinb1信号传导可以通过体内细胞极性复合物调节细胞 - 细胞连接。这项研究的重点是评估ephrinb1是使用爪蟾系统中上皮细胞中细胞 - 细胞连接信号传导的介体还是调节剂。我们提出了证据表明，Par-Complent蛋白Par-6是建立紧密连接所需的主要支架蛋白，与Ephrinb1相关，并受Ephrinb1的调节，从而控制了紧密的连接。使用早期爪蟾胚胎的上皮细胞，我们表明ephrinb1的损失或获得功能会破坏细胞细胞的接触和紧密连接。这项研究揭示了一种机制，即Ephrinb1与活性Cdc42竞争与Par-6结合，Par-6是Par-3/Par-3/Par-6/par-6/cdc42/apkc）的脚手架蛋白，并破坏了紧密连接相关蛋白（ZO-1，cingulin）的定位。该竞争会影响紧密连接的形成，并受到埃菲林B1的酪氨酸磷酸化的调节。