FBXL6 governs c-MYC to promote hepatocellular carcinoma through ubiquitination and stabilization of HSP90AA1
FBXL6 governs c-MYC to promote hepatocellular carcinoma through ubiquitination and stabilization of HSP90AA1
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FBXL6 通过泛素化和 HSP90AA1 的稳定来控制 c-MYC 促进肝细胞癌
DOI：
10.1186/s12964-020-00604-y
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发表时间：
2020-06-23
影响因子：
8.4
通讯作者：
Meng, Zhiqiang
中科院分区：
文献类型：
--
作者：
Shi, Weidong;Feng, Lanyun;Meng, Zhiqiang
热射蛋白90 (HSP90) AA1作为一种癌蛋白，调节其客户蛋白（包括c-MYC）的组装、操作、折叠和降解。然而，HSP90AA1的调控机制尚不清楚。方法利用肝细胞癌（HCC）标本的转录组rna测序数据检测FBXL6 mRNA的表达。采用免疫沉淀/质谱（IP/MS）方法对FBXL6的相互作用蛋白进行鉴定。采用共免疫沉淀法测定FBXL6与HSP90AA1的相互作用。通过体内泛素化实验确定FBXL6对HSP90AA1的调控作用。荧光素酶报告基因法和染色质免疫沉淀法（ChIP）测定了c-MYC对FBXL6的转录调控作用。采用免疫组化（IHC）染色法研究87例HCC标本中FBXL6与HSP90AA1蛋白表达的相关性。通过细胞计数和集落形成实验检测FBXL6对肝癌细胞体外生长的生物学效应。在小鼠肿瘤异种移植模型中研究了FBXL6对肝癌肿瘤生长的影响。结果我们发现孤儿F-box蛋白FBXL6是HSP90AA1的泛素连接酶，它是SCF （Skp1-Cul1-F-box蛋白）复合体的一个底物识别亚基。FBXL6促进k63依赖性HSP90AA1泛素化，使其稳定。通过TCGA数据分析，我们发现FBXL6在HCC组织中显著升高，且与c-MYC通路呈正相关。FBXL6在HCC中的积累通过阻止HSP90AA1降解导致c-MYC的稳定和激活。活化后的c-MYC直接结合FBXL6的启动子区域，诱导其mRNA表达。总之，我们的数据揭示了一个未知的FBXL6- hsp90a1 -c- myc轴可能与HCC的发生有关，我们提出抑制FBXL6可能是HCC治疗的一种有效的治疗策略。视频摘要
BackgroundHeat shot protein 90 (HSP90) AA1 functions as an onco-protein to regulate the assembly, manipulation, folding and degradation of its client proteins, including c-MYC. However, little is known about the mechanism of HSP90AA1 regulation.MethodsTranscriptome RNA-sequencing data of hepatocellular carcinoma (HCC) samples were used to detect the mRNA expression of FBXL6. Immunoprecipitation/Mass Spectrum (IP/MS) method was used to identify the interacting proteins of FBXL6. The co-immunoprecipitation assay was used to determine the interaction between FBXL6 and HSP90AA1. The in vivo ubiquitination assay was performed to determine the regulation of HSP90AA1 by FBXL6. Luciferase reporter and chromatin immunoprecipitation (ChIP) assays were used to determine the transcriptional regulation of FBXL6 by c-MYC. Immunohistochemical (IHC) staining was performed to study the correlation of FBXL6 and HSP90AA1 protein expression in 87 HCC samples. Cell counting and colony formation assays were implemented to detect the biological effects of FBXL6 on the growth of HCC cells in vitro. The effect of FBXL6 on HCC tumor growth in vivo was studied in a tumor xenograft model in mice.ResultsHere, we identified the orphan F-box protein FBXL6, a substrate recognition subunit of an SCF (Skp1-Cul1-F-box protein) complex, as the ubiquitin ligase for HSP90AA1. FBXL6 promoted K63-dependent ubiquitination of HSP90AA1 to stabilize it. Through analysis of the TCGA dataset, we found that FBXL6 was significantly increased in HCC tissues and positively correlated with c-MYC pathway. FBXL6 accumulation in HCC causes the stabilization and activation of c-MYC by preventing HSP90AA1 degradation. The activated c-MYC directly binds to the promoter region of FBXL6 to induce its mRNA expression.ConclusionCollectively, our data revealed an unknown FBXL6-HSP90AA1-c-MYC axis which might contribute to the oncogenesis of HCC, and we propose that inhibition of FBXL6 might represent an effective therapeutic strategy for HCC treatment.Video abstract