RNF121 Inhibits Angiogenic Growth Factor Signaling by Restricting Cell Surface Expression of VEGFR-2.
RNF121 Inhibits Angiogenic Growth Factor Signaling by Restricting Cell Surface Expression of VEGFR-2.
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DOI：
10.1111/tra.12353
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发表时间：
2016-03
期刊：
影响因子：
--
通讯作者：
Rahimi N
中科院分区：
文献类型：
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作者：
Maghsoudlou A;Meyer RD;Rezazadeh K;Arafa E;Pudney J;Hartsough E;Rahimi N
配体刺激促进RTK的下调，这是一种通过泛素化途径从细胞表面去除RTK的机制，导致RTK信号传导的暂时终止。RTK运输和成熟的内质网（ER）/高尔基室的分子机制知之甚少。VEGFR-2是一种原型RTK，在生理和病理性血管生成中起关键作用。在这里，我们证明了环指蛋白121（RNF 121），内质网泛素E3连接酶，在内皮细胞中表达，并调节VEGFR-2的成熟。RNF 121识别ER中新合成的VEGFR-2并控制其运输和成熟。RNF 121的过表达促进了VEGFR-2的泛素化，抑制了其成熟，导致VEGFR-2在细胞表面的存在显著减少。相反，在原代内皮细胞中，shRNA介导的RNF 121敲低降低了VEGFR-2泛素化并增加了其细胞表面水平。RNF 121的RING指结构域是其对VEGFR-2的活性所必需的，因为其缺失显著降低了RNF 121对VEGFR-2的作用。此外，RNF 121抑制VEGF诱导的内皮细胞增殖和血管生成。总之，这些数据鉴定RNF 121为限制VEGFR-2细胞表面存在及其血管生成信号传导的血管生成信号传导的关键决定因素。
Ligand stimulation promotes downregulation of RTKs, a mechanism by which RTKs, through the ubiquitination pathway are removed from the cell surface, causing a temporary termination of RTK signaling. The molecular mechanisms governing RTK trafficking and maturation in the endoplasmic reticulum (ER)/Golgi compartments are poorly understood. VEGFR-2 is a prototypic RTK that plays a critical role in physiologic and pathologic angiogenesis. Here we demonstrate that Ring Finger Protein 121 (RNF121), an endoplasmic reticulum ubiquitin E3 ligase, is expressed in endothelial cells and regulates maturation of VEGFR-2. RNF121 recognizes newly synthesized VEGFR-2 in the ER and controls its trafficking and maturation. Over-expression of RNF121 promoted ubiquitination of VEGFR-2, inhibited its maturation resulted a significantly reduced VEGFR-2 presence at the cell surface. Conversely, the shRNA-mediated knockdown of RNF121 in primary endothelial cells reduced VEGFR-2 ubiquitination and increased its cell surface level. The RING Finger domain of RNF121 is required for its activity toward VEGFR-2, as its deletion significantly reduced the effect of RNF121 on VEGFR-2. Additionally, RNF121 inhibited VEGF-induced endothelial cell proliferation and angiogenesis. Taken together, these data identify RNF121 as a key determinant of angiogenic signaling that restricts VEGFR-2 cell surface presence and its angiogenic signaling.