Hes-1 的類小泛素化修飾可調節 Hes-1 蛋白質的穩定及 GluR1 的表現

Abstract

轉譯後修飾作用\n(post-translational modifications) 包含甲基化\n(methylation)、磷酸化\n(phosphorylation)、泛素化\n(ubiquitination)、類小泛素\n化修飾\n(sumoylation) 等。過去有研究指出類小泛素化修飾可以調節目標蛋白\n質的穩定度，進而調節許多細胞內反應，例如：細胞核運輸作用、\nDNA 複\n製、調節轉錄作用、染色體分離、訊息傳遞、細胞週期調控、DNA 修補作用等\n現象。類小泛素化修飾是藉由一系列的酵素，使類小泛素這個蛋白質能夠修飾\n目標蛋白質的\nlysine\n殘基。\n類小泛素化修飾是一個可逆性動態修飾過程，類\n小泛素化修飾連結途徑包含有三個主要的步驟：\n活化 (activation)，結合\n(conjugation)，連接 (ligation)，它們分別是藉由\nE1、E2 和\nE3 這三種不同的\n酵素催化的。本篇研究主要是藉由類小泛素\nE3 連接酶 PIAS1 進行修飾作用，\n我們發現\nHairy and Enhancer of split 1 (Hes-1) 蛋白質可被類小泛素修飾。若\n將類小泛素\nE3 連接酶 PIAS1 突變，就無法讓野生型\nHes-1 進行類小泛素修\n飾化，證實\nPIAS1 的參與對於類小泛素化修飾扮演重要的角色。除此之外，\n將類小泛素目標蛋白質\nHes-1 序列上第八個位置的\nlysine 突變，會抑制\nHes-1 進行類小泛素化修飾。因此，透過\nPIAS1 所進行的類小泛素化修飾可以\n使目標蛋白質\nHes-1 蛋白質更為穩定。之後更進一步探討在空間學習與記憶\n中，Hes-1 進行類小泛素化修飾與\nGluR1 蛋白質表現的關係。實驗結果顯示，\nHes-1 進行類小泛素化修飾使空間學習與記憶變差並使\nGluR1 蛋白質表現下\n降。

There are several post-translational modifications including methylation、\nphosphorylation、ubiquitination、sumoylation, etc. Previously studies\nindicated that sumoylation can regulate target protein stability. Sumoylation\nalso modulates many cellular processes, including nuclear transport, DNA\nreplication, transcription, chromosome segregation, signal transduction, cell\ncycle and DNA repair. Sumoylation is a process mediated by SUMOs which\nare attached to specific lysine residues of target proteins by the action of a\nseries of enzymes. Sumoylation is a dynamically reversible process.\nSumoylation consists of three steps：activation, conjugation and ligation,\nwhich are respectively mediated by E1, E2 and E3 ligase. This study focuses\non SUMO modification by E3 ligase. Here, we identified a new target protein,\nHairy and Enhancer of split 1 (Hes-1), for SUMO conjugation. The E3 ligase\ndeficient mutant of PIAS1 that leads to failure of Hes-1 protein sumoylation.\nWe demonstrared that PIAS1 is involved in SUMO modification of Hes-1. In\naddition mutantion of Hes-1 protein on lysine 8 residue that inhibits the\nsumoylation of Hes-1. Therefore, sumoylation of Hes-1 regulates the protein\nstability of Hes-1. Further study of the relationship between sumoylation of\nHes-1 and GluR1 in spatial memory formation indicated that spatial memory\nis impaired and GluR1 protein expression is decreased upon sumoylation of\nHes-1.