Daxx調控非編碼長RNA之鑑定及分析

Abstract

Daxx 蛋白質最初被證明在細胞質內與Fas受體的凋亡區段互相結合，並扮演訊息傳遞重要的角色，然而許多報導指出，Daxx主要在細胞核內執行基因轉錄調節的功能。為了更進一步瞭解Daxx 對於基因表現的影響，本實驗利用微陣列晶片系統性的找尋Daxx調控的編碼基因(protein-coding gene) 及長非編碼RNA (large intergenic non-coding RNA)。分析結果指出當抑制Daxx表現時，顯著地調控655個基因的表達，進一步利用基因功能性分析，發現其中許多基因與細胞型態及癌症生成高度相關。此結果暗示Daxx可能參與癌症轉移的調控。另一方面，當抑制Daxx表現時，細胞內有104個長非編碼RNA表現量出現顯著差異。進一步利用生物資訊分析方法，篩選出Daxx可能調控的長非編碼RNA，我們並利用補救實驗及反轉錄定量聚合酶鏈式反應( RT-qPCR) 驗證該分析結果。結果證實12個長非編碼RNA受到Daxx調控，其中包含功能已知的lincRNA, 如JPX, NEAT1及MIAT。接著，我們利用RNA干擾技術發現其中一個長非編碼RNA，linc4971的表現對於其上游基因,ZNF703及ERLIN2具有抑制的作用。整體來說，本實驗結果除了提供Daxx 可能調控的標的基因及長非編碼RNA，並指出Daxx可藉由調控長非編碼RNA影響下游基因的表現。

The death domain-associated protein (Daxx) participates in various biological processes depending on its sub-cellular localization. In the nucleus, Daxx, as a transcriptional coregulator, interacts with various proteins, including transcription factors, to regulate gene expression. Although many Daxx-regulated genes have been reported, a genome-wide analysis of gene expression profile regulated by Daxx largely remains unclear. Here, we used microarray analysis to identify Daxx-regulated protein-coding genes as well as non-coding RNAs. 655 genes were significantly regulated in Daxx knockdown cells. Gene ontology analysis demonstrated that Daxx-regulated genes showed significant asssociation with cell morphology and cancer, suggesting that Daxx may play a role in tumor formation. Moreover, by combining microarray data and bioinformatic analysis, we identified 45 Daxx-regulated large intergenic non-coding RNAs (lincRNAs). Some identified lincRNAs, such as JPX, NEAT1 and MIAT, are functionally well-known, while most are recently defined transcripts. Notably, knockdown of identified lincRNA linc-4971 resulted in a activation of nearby gene expression, suggesting that this lincRNA may act as regulatory node in Daxx-mediated transcriptional pathways.