| xiqun zhu,Renmin Hospital of Wuhan University. Extracellular and cytoplasmic regions of LRIG1 play a negative role in EGFR activity: Findings of a radioligand-binding assay. Oncol Transl Med, 2017, 3: 137-142. |
| 通过放射受体结合实验可以得出LRIG1的胞外段和胞质段都能抑制EGFR的活性 |
| Extracellular and cytoplasmic regions of LRIG1 play a negative role in EGFR activity: Findings of a radioligand-binding assay |
| Received:July 25, 2016 Revised:July 23, 2017 |
| DOI：10.1007/s10330-016-0174-4 |
| 中文关键词: LRIG1；胞外段；胞质段；结合位点；EGFR |
| 英文关键词: leucine-rich repeats and immunoglobulin-like domains 1 (LRIG1); extracellular domain (ECD); cytoplasmic domain (CPD); binding site; epidermal growth factor receptor (EGFR) |
| 基金项目: |
| Author Name | Affiliation | E-mail | | xiqun zhu | Renmin Hospital of Wuhan University | 1130076364@qq.com | | Renmin Hospital of Wuhan University* | ,Renmin Hospital of Wuhan University | yiwei920714@163.com |
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| 中文摘要: |
| 目的：表皮生长因子受体（epidermal growth factor receptor ，EGFR）通过与配体结合来促进肿瘤的生长，之前的研究认为多亮氨酸重复区免疫球蛋白样蛋白1（Leucine-rich Repeats and Immunoglobulin-like domains 1，LRIG1）可以抑制EGFR的这一作用。本文主要研究LRIG1和EGFR的相互作用，和阐明LRIG1的胞外段和胞内段降低EGFR信号活动的机制。方法：构建pIRES2-EGFP-3XFLAG-LRIG1-ET 和p3FLAG-LRIG1-TC两种质粒体，分别表达胞外跨膜段和胞质跨膜段，p3XFLAG-CMV-9-LRIG1质粒体表达LRIG1全长段。将它们分别转入U251胶质瘤细胞中，通过125I-EGF放射结合实验来确定转染后细胞表面的EGFR的数量和亲和性。结果：三种转染细胞的解离常数都增强，其中转染了表达胞外段质粒体的细胞变化最明显，增加了1.36倍，并且三种细胞的最大受体结合位点都减小，其中转染了全长段的细胞下降最明显，下降了40.05%。结论：LRIG1的胞外段和胞质段都能负性调节EGFR信号的活性，其中胞外段可能是通过干扰EGFR和配体结合并且能增强LRIG1胞质段的作用，胞质段在接近EGFR时促进它的降解。LRIG1下调EGFR调节信号可能是通过这两种机制。 |
| 英文摘要: |
| Objective Leucine-rich repeats and immunoglobulin-like domains 1 (LRIG1) is a newly identified human
gene that inhibits the epidermal growth factor receptor (EGFR), which on combining with a ligand, can drive
tumor growth. This study investigated the interaction between human LRIG1 and EGFR and attempted
to delineate the functions of as well as the mechanisms used by the extracellular (ECD) and cytoplasmic
(CPD) domains of the human LRIG1 protein to downregulate human EGFR signaling activity.
Methods Two constructed chimeric eukaryotic expression vectors, pIRES2-EGFP-3XFLAG-LRIG1-
ET and p3FLAG-LRIG1-TC, encoding the extracellular and transmembrane regions (LRIG1-ET) and the
transmembrane and cytoplasmic regions (LRIG1-TC), respectively, and the plasmid p3XFLAG-CMV-9-
LRIG1 encoding full-length LRIG1 (LRIG1-FL) were transfected into the human glioma cell line U251 or
primary astrocytoma cells by using liposomes. The number and affinity of cell surface EGFR on transfected
cells was determined by 125I-EGF binding assay.
Results The dissociation constant (KD) values for EGFR were higher, and the maximum increase was
observed in the cells transfected into LRIG1-ET (1.36 folds). The number of maximal binding sites (Bmax)
of the receptors was decreased in all transfected cells; the maximum decrease was noted in the cells
transfected into LRIG1-FL (40.05%).
Conclusion Both the ECD and CPD of LRIG1 are important to negate EGFR signaling. The ECD may
interfere with the binding between EGFR and its ligand and facilitate the functions of CPD. The CPD may,
when brought in proximity to EGFR, enhance receptor degradation. These two mechanisms can contribute
to the downregulation of EGFR-mediated signaling by LRIG1. |
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