2009-08-012024-05-17https://scholars.lib.ntu.edu.tw/handle/123456789/678863摘要：後生遺傳/上位遺傳(Epigenetics)在不影響DNA序列的前提下，經由DNA甲基化、組蛋白(Histone)修飾及功能性RNA之作用途徑，影響特定基因之表現。此等上位遺傳對於基因體之修飾作用即為幹細胞之所以有別於已分化體細胞之差異所在。上位遺傳於各類細胞間不同之印記是具有可逆性的。這種可逆性是謂幹細胞及再生醫學研究之關鍵課題。目前對於後生遺傳調控基因表達之機制所知仍相當有限。本計畫將有系統的探討小鼠與豬之間葉幹細胞於體外及體內誘導分化為肝細胞、脂肪細胞、軟骨及硬骨細胞過程中，後生遺傳層次調控基因表達之機制。 本整合型計劃之其他六個子計畫，正利用綠色或紅色螢光基因轉殖動物(豬與鼠)之骨髓間葉幹細胞或椎間盤髓核細胞為材料，積極建立骨質疏鬆、肝臟損傷、心肌梗塞症、動脈粥狀硬化、關節軟骨損傷及椎間盤退化造成之下背部酸痛的幹細胞治療動物模式。此等螢光基因轉殖動物的骨髓間葉幹細胞已證實能夠在體外長期培養而仍然保持其螢光物質的表現，因此非常適合利用其螢光特性來追蹤其移植後的去向及分化程度，並有助於將此等移植後之細胞重新分離出，已進行分子與後生遺傳調控之分析。 本子計畫將充分利用於體內及體外誘導分化前後之綠色螢光骨髓間葉幹細胞為材料，經由分析誘導分化前後：基因(coding gene)及功能性RNA（尤其是microRNA）表達質與量之差別，DNA甲基化，與各式組蛋白修飾(各個組蛋白不同胺機酸之甲基化及乙醯化)之差異，深入探究間葉幹細胞分化為成骨細胞(osteocyte) 、脂肪細胞、軟骨及肝臟細胞(hepatocyte)之分子與後生遺傳(Epigenetic)調控機制。此等研究之成果，不但有助於建立以幹細胞為中心之肝臟修復與骨質疏鬆治療的動物模式，本計畫更將對後生遺傳機制維持各式幹細胞之多分化潛能及調控幹細胞分化，帶來突破性之瞭解。這些知識勢必顯著提升以幹細胞為中心之再生醫學成功率。 <br> Abstract: Recently it has been demonstrated that the epigenetic modifications that do not change the DNA sequences but change gene activities marks the differences between stem cells and the differentiated somatic cells. These epigenetic levels of gene expression regulation include DNA methylation and modification of the chromatin packaging proteins, as well as functional small RNAs that regulate gene activity post-transcriptionally. The tight and complicate epigenetic regulatory mechanisms are most likely the key to maintain pluripotency, trigger and control cell-lineage specific differentiation, but very little is known about exactly how these are done. Over the last several years of intensive study about the genetic networks controlling mesenchymal stem cell differentiation, there has been a rough understanding for the key genetic factors involved in this process. However, it is far from fully understood that how these genes are regulated upon induced differentiation. Taking advantage of the animal models being established in the other subprojects, we will study the detailed Epigenetic regulatory mechanisms during the process of mesenchymal stem cell differentiation towards osteoblast, adipocyte and hepatocyte. In addition, the homing and differentiation of the mesenchymal stem cells after transplanting to preconditioned liver and articular cartilage damaged recipients will also be evaluated. The criteria we will be analyzing includes the changes of overall gene expression and microRNAs expression profile at specific differentiating time point as indicated by lineage and stage specific markers. We will pay particular attention on the epigenetic modifiers (DNA methyltransferases, histone modifying proteins and functional non-coding RNAs), as well as lineage specific signaling transducers and patterning factors. We will also study the DNA methylation and histone modification changes of the target genes upon stem cell differentiation. From these precious dataset, we shall be able to figure out many previously unidentified epigenetic regulatory pathways upon mesenchymal stem cell (MSC) differentiation towards osteoblast, adipocyte and hepatocyte. We will also have the opportunity to reveal the genetic and epigenetic regulatory network from the initial epigenetic modification to the cascades that trigger stem cells to differentiate into different lineages. These analyses can significantly facilitate the establishment of the most efficient in vitro differentiation and in vivo transplantation procedures attempted by researchers from subprojects 1, 2, 4 & 5. Moreover, the result from these studies will elucidate the mechanisms behind cell plasticity in general and will therefore provide a big breakthrough and can easily be applied to the fields of nuclear reprogramming, stem cell research and regenerative medicine.DNA甲基化間葉幹細胞再生醫學後生遺傳調控機制microRNAsmesenchymal stem cell differentiationregenerative medicineepigenetic regulationDNA methylationmicroRNAs