VHL调控PHD3底物稳定性抑制发育性凋亡引发嗜铬细胞瘤的分子机制研究

抑癌基因VHL不同突变导致不同亚型VHL遗传性肿瘤综合征。VHL/PHD3典型底物HIFα蛋白降解异常不能完全解释VHL突变肿瘤基因型/表型关系，提示VHL可通过调控其他蛋白稳定性参与肿瘤发生。我们前期工作发现，VHL突变嗜铬细胞瘤（PCC/PGL）中c-Jun与p53等发育性凋亡抵抗通路异常激活，该过程不依赖HIFα但依赖VHL E3连接酶与PHD3羟基化酶活性。故提出假说：VHL突变通过影响HIFα之外的PHD3底物稳定性调控交感神经前体细胞（SAPs）向嗜铬细胞分化过程，促使嗜铬细胞逃避发育性凋亡引发PCC/PGL。本项目拟创建hPSCs（人诱导多功能干细胞）来源嗜铬细胞模型，通过基因编辑技术获得携带不同VHL突变的细胞，揭示VHL调控的SAPs向嗜铬细胞分化过程及其发育性凋亡抑制的关键分子，阐明VHL突变PCC/PGL发生新机制，为PCC/PGL及其他VHL相关疾病治疗提供新思路。

Different mutations of the von Hippel–Lindau (VHL) tumor suppressor gene cause different subtypes of VHL hereditary cancer syndrome. The theory on dysregulation of VHL/PHD3’s canonical substrate, HIFα, can not fully explain the complex genotype/phenotype manifestation within VHL disease，suggesting that VHL can participate in tumor development by regulating the stability of other proteins. In our previous study, we found that pathways such as c-Jun and p53 in developmental culling inhibition were abnormally activated in VHL mutated pheochromocytoma and paraganglioma (PCC/PGL), which depended on the activity of VHL E3 ligase and PHD3 hydroxylase. Therefore, we hypothesize that VHL mutation regulates the differentiation process of sympathetic precursor cells (SAPS) into chromaffin cells by affecting the stability of PHD3 substrates other than HIF α, and promotes chromaffin cells to escape the developmental culling and initiate PCC/PGL. In this proposal, the molecular mechanism of PCC/PGL induced by VHL mutation will be studied by establishment of chromaffin cell model derived from hPSCs (human induced pluripotent stem cells). Taking the advantages of natural similarity between the cell model with the human adrenal medulla including cell structure, cell composition and genetic background of chromaffin cells, hPSCs and chromaffin cells with different VHL mutations will be obtained by crisper case 9 gene editing in vitro. In order to reveal different types of VHL mutations (Type 1 and Type 2A/B/C) on the differentiation of sympathetic neuronal precursor cells (SAPs), the effect of VHL protein (pVHL) on the stability of the targets will be investigated. This project will provide a new strategy for the treatment of PCC/PGL and other VHL related diseases.