染色體是由DNA與許多不同的染色體蛋白質經自我組織成多層次的複雜結構。我們的研究興趣是探討染色體組成、結構、形成機制與動態變化,進而瞭解染色體結構與DNA功能的相互關係,核心研究主題包括DNA破損反應、有絲分裂時基因體穩定性維持與減數分裂時產生遺傳變異的生化機制,這些課題不僅是遺傳學的基礎,也與細胞癌化、細胞或個體老化、染色體異常、遺傳變、不孕症與基因體演化有重要關聯。
我們的主要生物模式是酵母菌減數分裂。為了產生新的遺傳變異,進行減數分裂的酵母菌會自發性產生雙股DNA斷裂,然後啟動DNA破損反應,促成來自父母雙方的同源染色體進行配對,然後由頭至尾形成拉鍊狀的複雜蛋白結構稱作「聯會複合體(synaptonemal complex)」,將同源染色體平行並排,確保DNA重組互換發生於父母雙方的同源染色體間而 非發生於父方或母方的姐妹染色體間。若DNA破損反應或同源染色體間配對與聯會有缺失,細胞周期檢查點(cell cycle checkpoint)會啟動,細胞周期便停止於減數分裂前期,同源染色體無法繼續進行分離。我們研究的重心在探討DNA破損、重組反應的機制、聯會複合體形成機制,以及前三者與細胞周期檢查點的耦合關係。
圖一、酵母菌減數分裂專一性染色體結構蛋白Red1結合小泛素鏈以控制聯會複合體的形成。圖示為酵母菌減數分裂粗絲期之染色體經免疫螢光染色,綠色為聯會複合體主要的結構蛋白Zip1,紅色為Red1蛋白,染色體的DNA經DAPI染色呈藍色。red1I758R酵母菌突變株所表達的Red1蛋白無法與小泛素鏈結合 因此不能形成拉鍊狀的聯會複合體。 (此圖為國防醫學院生命科學研究博士班學生林鋒銘之實驗結果)
Figure 2. Yeast vacuole is in contact with the nuclear envelope (NE) via nucleus-vacuole junctions (NVJs) during meiosis. (A) An amphiphilic fluorescent dye, FM 4-64, was applied to visualize vacuolar membranes in live meiotic cells that expressed Zip1-GFP, Nvj1-GFP and Nup49-tdm2. Nvj1 is a nuclear inner membrane, that interacts with the vacuolar membrane protein Vac8 to promote formation of nucleus-vacuole junctions. Nup49 is a component of nuclear pore complex. Zip1 was used here a meiotic prophase marker. (B) The Nvj1-GFP patches underwent scission during two round of meiotic nuclear divisions. Time-lapse live cell imaging of Nvj1-GFP and Nup49-tdm2 from mid-prophase to the second meiotic nuclear division (MII).
Figure 3. Blue light acts as a double-edged sword in regulating sexual development of Trichoderma reesei, an industrially important cellulolytic filamentous fungus. The mating assay. Two haploid cultures were inoculated on a MEA plate. If sexual development occurs, stromata will be found at the interaction zone (marked by white arrow). Sexual development of wild-type, the Δblr1,2 double mutant and the Δenv1 diploid mutants under constant light illumination or constant darkness. The BLR1 and BLR2 proteins are blue-light receptors, ENVOY (ENV1) is a negative regulator that functions to tolerate continuous exposure to light and dampens the capacity of the fungus to perceive changes in light intensity.
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