2013-01-012024-05-14https://scholars.lib.ntu.edu.tw/handle/123456789/656926摘要：探討SMYD3甲基轉移酵素如何修飾histone及促進癌細胞生長藉由histone修飾(histone modification)而造成上位基因(epigenetic) 的調控，對於DNA的轉錄、複製、修復有極重要的影響。大多數的histone甲基轉移酵素(histone methyltransferases, HMTs)含有一個能專一性修飾histone H3或H4之lysine residue的SET遺傳保留功能性區塊(conserved SET domain)。在SET遺傳保留功能性區塊中及其前後位置有許多相似的胺基酸序列。在SET家族中雖然SET1及SET2的功能已被完整的研究，但另一些包含SET功能性區塊的蛋白質，其功能則尚待探討。我的實驗室長期著重於染色質、端粒及DNA修復相關之研究。我們偶然間發現酵母菌的Set5蛋白質及其人類同源蛋白質hSMYD3具備甲基化H2A.Z的活性。SMYD3已被證實在許多種類的腫瘤中會高度表現，其中包括乳癌細胞；SMYD3的活化亦能促進癌症增生，但除了已知SMYD3能甲基化組蛋白H3在lysine 4的位置並增進端粒酶表現，其他細節的調控機制仍不明朗。本計畫的目的在於分析SMYD3在腫瘤形成過程中扮演的角色。初步結果顯示，不論是在試管中或是細胞內進行實驗，SMYD3都具有二甲基化H2A.Z lysine 102位置的活性。針對lysine 102位置進行突變則會使其失去增生癌症細胞的能力，特別是在乳癌細胞株中。已知包含H2A.Z的nucleosomes會參與在調控基因表現中，因此，首先我們會先測定SMYD3是否能藉由修飾H2AZ來影響細胞週期調控因子，並由此促進細胞週期的進行。第二部分，我們會篩選出受到SMYD3調控而活化的基因，且觀察其轉錄活性是否受到H2AZ lysine 102位置的二甲基化影響。第三部分，我們要找出H2A.Z的reader。第四部分，若 lysine 102位置在乳癌細胞中為一專一性的histone標記，我們計畫檢查藉由SMYD3/H2AZ活化的乳癌惡性腫瘤，如何影響小鼠腫瘤生長及檢查臨床檢體的關聯性與存活率。這項研究成果將能增進我們對於在癌症中，以SMYD3為媒介的上位基因調控的了解，更重要的是，此專一性的histone標記將可提供未來癌症基礎研究與臨床診斷治療的一個新方向。<br> Abstract: Study how SMYD3 methyltransferase modifies histone and promotes cancer proliferationHistone modification has profound epigenetic effects on the accessibility of the associated DNA for transcription, replication and repair. Most histone methyltransferases (HMTases) contain a conserved SET domain which targets to specific lysine residues of histone H3 or H4. There is considerable sequence conservation within the SET domain and within its flanking regions. While the function of SET1 and SET2 have been well characterized, the functions of other SET domain containing proteins are not that clear. Our lab studied topics in chromatin, telomere and DNA repair for a long time. We serendipitously identified that both yeast Set5 and its human ortholog hSMYD3 can methylate H2AZ. SMYD3 was discovered to be highly expressed in various tumors including breast cancers. SMYD3 also promotes cancer proliferation, but the detail mechanism is elusive except that SMYD3 methylates H3K4 and promotes telomerase expression. This project will focus on analyzing the function of SMYD3 in tumor formation. In our unpublished data, we found that SMYD3 dimethylated H2AZ lysine 102 in vivo and in vitro. Mutation of K102 lost its ability to promote cancer proliferation, especially in breast cancer cell lines. H2AZ-containing nucleosomes are involved in the regulation of gene expression. Therefore, we will first determine whether SMYD3 is able to regulate expression of key cell cycle regulators and promote cell cycle through H2AZ. Second, we will screen overall SMYD3-facilitated expression and determine whether these transcriptional activations are mediated by the dimethylation of lysine102 of H2AZ. Then we want to find out the reader of H2A.Z K102me2. Finally, if lysine 102 dimethylation is a specific histone mark in breast cancer cells, we plan to examine the SMYD3/H2AZ-mediated breast cancer malignancy in mice and in clinic samples. Accomplishment of this project will advance our knowledge on molecular mechanisms of SMYD3-mediated epigenetic control in cancers and provide significant contributions to the field of specific histone marks in cancer biology.癌細胞histonesmyd3cancerhistonesmyd3