研究Bcp1調控核醣體及酸肌醇生合成途徑之機制

2010-10-012024-05-18https://scholars.lib.ntu.edu.tw/handle/123456789/707549摘要：本計畫將研究 Bcp1 如何參與調控大核醣體的合成過程。核醣體是由rRNAs 及核醣蛋白組合成的聚合物，是蛋白質合成的工廠。依分子量，可區分成小及大核醣體。 rRNAs 在核仁轉錄後，需要經過修飾、剪切，並與核醣蛋白間產生正確的結合，才能具有完整的功能。在真核生物中，核醣體的合成需要超過200 個輔助蛋白參與。這是一種非常浩能的過程，因此，細胞必須嚴格調控核醣體的合成。如果合成出錯，會影響到核醣體的正確性，輕微時會降低細胞生長活性，嚴重時會導致細胞死亡。很多的人類疾病，已知是因為核醣體功能缺失而造成。因此，了解核醣體的合成及調控，是了解細胞功能的一項重要資訊。 Bcp1是運送Mss4 出細胞核的蛋白。Mss4 是在細胞膜上合成二磷酸(4,5)酸肌醇的磷酸酶。酸肌醇是一種小分子訊號，調控了很多重要的細胞功能。Mss4 具有NLS (Nuclear localization signal) 序列，被轉譯出來後，Mss4 會被送入細胞核中，而Bcp1 則是將這些Mss4 再送出細胞核。經由調控核內外Mss4 的比例，細胞可以控制酸肌醇的產量。最近，Bcp1 也被發現跟大核醣體的合成有關，當Bcp1 在酵母中被去除時，大核醣體的合成會大量減低，小核醣體的合成卻不受到影響。但是其調控機制，卻仍是未知。在這篇研究計畫中，我們將透過蛋白質純化、遺傳學分析、產生突變株等方法， 來剖析Bcp1 是如何調控這兩條生合成途徑及之間可能的交互作用。這個研究成果，將幫助我們了解細胞是如何調控蛋白質合成及細胞生長的機制。<br> Abstract: Bcp1 is an essential gene involved in export of Mss4, a phosphatidylinositol (PI) 4-phosphate 5-kinase to generate PI4,5P2 at the plasma membrane. PI signals are essential for many important cellular functions. Recently, Bcp1 is also known involved in the synthesis of large ribosomal subunits. However, the mechanism is still unknown. Ribosomal subunits are large macromolecular complexes composed of rRNAs and ribosomal proteins. The synthesis of ribosomes is an energy intensive process that is required to be tightly regulated according to cellular needs. In addition, the assembly of ribosome requires over 200 transacting factors in the eukaryotic cells. Additional assembly factors are still being identified and the specific function of many of these factors is unknown. Knowing how this pathway is regulated in the cells is an important question for understanding the control of cell growth. My lab will use budding yeast (Saccharomyces cerevisiae) as a model system to study the connection between PI signaling pathway and the synthesis pathway of 60S subunits. Basically, the level of ribosomal subunits will be tested in the Bcp1 and PI pathway mutants; PI signaling pathway will be also tested in the mutants showing 60S synthesis defects. Bcp1 containing protein complexes will be purified and analyzed to dissect when Bcp1 acts in the pathway of 60S biogenesis. In the long term goal, my lab wants to establish a network connection between 60S export pathway, mRNA export pathway, and other important cellular pathways via PI signaling. This model will be also tested in the mammalian cells to see if it is conserved in evolution.核醣體核醣體生合成酸機醇蛋白質合成RibosomeRibosome biogenesisPhosphoinositolBcp1Mss4研究Bcp1調控核醣體及酸肌醇生合成途徑之機制