2017-08-012024-05-16https://scholars.lib.ntu.edu.tw/handle/123456789/666819摘要：PHRF1具有可對受質進行泛素化的 RING domain，先前研究發現PHRF1透過泛素化TGIF可促進TGF-非典型訊息傳遞；在小鼠模型中，PHRF1抑制急性骨髓性白血病(acute promyelocytic leukemia, APL)的生成，因PML-RAR重組蛋白與PHRF1競爭和TGIF結合的能力，造成cPML被TGIF泛素化而無法進入細胞質與SARA作用，因而阻斷發揮TGF-訊息傳遞。另外我們的實驗結果發現PHRF1具有調節非同源末端黏合（non-homologous end-joining, NHEJ）的功能，我們推測PHRF1可連接二甲基化和三甲基化的組蛋白H3K36和Nbs1並對PARP1泛素化，使得PHRF1在DNA雙股斷裂時調控細胞的非同源末端黏合修補; 然而對PHRF1在癌症侵入和轉移的研究非常稀少。 本計畫的初步結果中我們發現PHRF1在肺癌和口腔癌的人類癌症標本中約有75％有中高表現量，過量表現PHRF1的A549/CL1-0/CL1-5細胞可增加細胞移動和突破膠質的侵入能力，進一步分析發現 PHRF1影響上皮間質細胞轉換(EMT)中轉錄因子Zeb1的表現，同時PHRF1 C端的SRI區域可與RNA polymerase II (RNAPII)複合體中最大次單元Rpb1被磷酸化的CTD區域作用，短缺SRI的PHRF1無法提高Zeb1的表現量，推測PHRF1可能藉由影響Rpb1對mRNA的延長作用而增加Zeb1的表現；降低PHRF1表現的細胞在低氧狀態處理時，Zeb1的表現仍可被有效抑制，證明PHRF1藉由調控Zeb1的表現量影響癌細胞侵襲和轉移的能力。 <br> Abstract: PHRF1 recognizes methylated histones via PHD domain and ubiquitinates substrates by RING domain. PHRF1 promotes non-canonical TGF- signaling through TGIF ubiquitination and suppress the formation of acute promyelocytic leukemia (APL) in mouse APL models. PML-RAR fusion protein interferes the TGIF breakdown by competing with PHRF1’s binding to TGIF. Additionally, we report a novel function of PHRF1 in modulating non-homologous end-joining (NHEJ). Ablation of PHRF1 decreases the efficiency of non-homologous end-joining (NHEJ), while PHRF1 overexpression leads to an elevated NHEJ in H1299 reporter cells. Furthermore, PHRF1 mediates PARP1 polyubiquitination for proteasomal degradation. We propose that PHRF1 is a key factor to link H3K36 methylation and NBS1 to promote NHEJ upon DNA damage insults. However, little is known regarding its function in tumorigenesis. Here we report a novel role of PHRF1 in cancer invasion and metastasis. PHRF1 affected transwell invasion and metastasis by modulating the transcriptional levels of Zeb1, a prominent regulator involved in epithelial-mesenchymal transition (EMT). The C-terminal domain (namely SRI, Set2 Rpb1 Interacting domain) of PHRF1 associated with the phosphorylated C-terminal repeat domain (CTD) on pSer2/pSer5 of Rpb1, the largest subunit of RNA polymerase II, and bound to the proximal region adjacent to the transcription start site (TSS) of Zeb1. SRI-deleted PHRF mutant was unable to increase Zeb1’s expression. Furthermore, PHRF1 depletion was able to compromise Zeb1 expression under hypoxia condition. Collectively, PHRF1 might take the stage at the invasion and metastasis by modulating the expression of Zeb1. However, several questions remained to be addressed.PHRF1Zeb1Zeb2VHLPHRF1Zeb1Zeb2VHLPHRF1參與癌症轉移機制之探討