腦指蛋白（Brain Finger Protein, ZNF179）這個基因屬於環指（RING finger）家族中的一員，已知腦指蛋白主要表現在腦部，而在我們實驗室先前的研究則發現在 P19 細胞分化成神經細胞的過程中，腦指蛋白的表現量會隨著神經細胞的分化逐漸的增加，而在神經細胞分化的過程中抑制腦指蛋白的表現則會明顯的影響 P19 細胞的神經分化。然而對於 ZNF179 基因在細胞中作用的機制，目前並不清楚。因此在本研究中我們藉由酵母雙雜交系統（yeast two-hybrid）試著找出與腦指蛋白有交互作用的蛋白質，希望由此能進一步的來了解 ZNF179 基因的作用機制。實驗發現 ZNF179 會與早幼粒細胞白血病鋅指蛋白（Promyelocytic leukemia Zinc-Finger；PLZF）有交互作用。利用免疫沈澱法（immunoprecipitation）也進一步地證實 ZNF179 與 PLZF 的確有交互作用。此外，在螢光免疫染色實驗中，也發現到原本分布在細胞質和細胞核中的 ZNF179，會受到 PLZF 表現的影響，進入細胞核中的核質體（nuclear bodies）。這樣的發現不僅再度證明了腦指蛋白與 PLZF 的交互作用，也暗指著 ZNF179 會隨著 PLZF 進入細胞核中核質體，進而執行某些作用。已知 PLZF 是一個轉錄抑制因子，會召集（recruit）核共抑制複合物，抑制基因的轉錄作用，使得細胞無法進行分化。而藉由報導基因的活性測定發現 ZNF179 並不具有轉錄調控的能力，也不影響 PLZF 的轉錄抑制作用，代表 ZNF179 與 PLZF 之交互作用應該不是共同作用於轉錄抑制功能。於是，我們推測那是否 ZNF179 與 PLZF 會共同作用於 PLZF 的目標基因。從過去研究找出 PLZF 基因會抑制 MYC 表現，使細胞周期停滞在 G1 期。於是，我利用了即時定量反轉錄-聚合酶連鎖反應觀察細胞內生性 MYC 的 mRNA 表現量。結果發現在 293T 細胞中 PLZF 對 MYC 確實有明顯的抑制現象，在大量表現 ZNF179 的組別中，MYC 的表現量也明顯的降低。當 PLZF 與 ZNF179 在細胞中共同表現時，同樣可以抑制 MYC mRNA 的表現量。

ZNF179, a novel gene with unknown function, belongs to the RING finger protein family, which is highly expressed in the brain. RING finger-containing proteins are often part of multi-protein complexes. Previous studies in our laboratory demonstrated that the expression of ZNF179 is remarkably increased in the retinoic acid-induced neural differentiated P19 cells and ZNF179 knock-down significantly attenuates neural differentiation. To investigate the molecular mechanisms of ZNF179 function, A yeast two-hybrid screen was performed to identify the ZNF179 interacting proteins. In the experiments, mouse ZNF179 was fused to the LexA DNA binding domain and used as bait to screen mouse brain cDNA library fused to the Gal4 transcriptional activation domain. From the screening, promyelocytic leukemia zinc-finger (PLZF) fragments were identified. Interaction was double confirmed by yeast two-hybrid analysis and co-immunoprecipitation (IP) assays. Immunofluorescence analysis further revealed that PLZF can recruit ZNF179 to the PLZF nuclear bodies. These results indicated that the two proteins did interact with each other in vivo. PLZF can alter the sub-cellular localization of ZNF179. A luciferase reporter gene assay suggested that ZNF179 have no transcriptional ability and is not required for transcriptional repression by PLZF. MYC is a target gene repressed by PLZF. We used Q-RT-PCR analysis to detect the MYC mRNA expression, which was suppressed by ZNF179 in 293T cells.

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