本文關(guān)鍵詞：PGC-1α調(diào)節(jié)Hepcidin表達及鐵動態(tài)平衡的分子機制研究　出處：《南京師范大學》2011年碩士論文　論文類型：學位論文

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【摘要】：在成年人體內(nèi),鐵離子的水平處在一個非常精細的動態(tài)平衡調(diào)節(jié)之中。如果這個平衡被打破,會導致鐵離子的缺失或者過載,從而引發(fā)一系列的疾病。在鐵離子的動態(tài)平衡調(diào)節(jié)機制中,Hepcidin起著至關(guān)重要的作用。Hepcidin能結(jié)合到細胞表面的鐵離子的關(guān)鍵輸出通道Ferroportinl (FPN1)上,導致FPN1的泛素化并在溶酶體內(nèi)降解,從而破壞鐵離子的動態(tài)平衡。Hepcidin的表達是高度活潑可控的,受到細胞內(nèi)外多種刺激因素如缺氧、內(nèi)質(zhì)網(wǎng)壓力和炎癥的調(diào)節(jié)。特別需要指出的是,在慢性炎癥病人體內(nèi)Hepcidin的表達比健康人群高,從而發(fā)生炎性貧血(anemia of inflammation,AI)。目前僅知道炎性因子IL-6能通過STAT-3 (signal transduction and activator of transcription-3)信號通路上調(diào)Hepcidin的表達,但對炎癥刺激與鐵動態(tài)平衡之間的媒介分子仍不是很清楚。 轉(zhuǎn)錄共激活因子PGC-1α(peroxisome proliferator activated receptorγcoactivator1α)是重要的能量代謝調(diào)節(jié)因子,它能夠選擇性地和核轉(zhuǎn)錄因子(包括HNF4α(hepatic nuclear factor 4α))發(fā)生相互作用,激活下游紛繁眾多的代謝通路�，F(xiàn)已有研究表明,Hepcidin啟動子含有HNF4α的保守結(jié)合位點,并且在HNF4α肝臟特異性敲除的小鼠中,Hepcidin的mRNA表達水平顯著升高。綜合以上前人的研究結(jié)果,我們不難發(fā)現(xiàn),炎性信號、PGC-1α、HNF4α以及Hepcidin之間似乎存在著千絲萬縷的聯(lián)系,但是,這其中具體的信號轉(zhuǎn)導機制到底如何呈現(xiàn)? 為了回答這個問題,本論文分別在細胞和整體動物水平上進行研究。在體外細胞實驗中,我們采用PGC-1α過表達腺病毒感染HepG2和HuH7人肝癌細胞株,發(fā)現(xiàn)無論是在轉(zhuǎn)錄還是翻譯水平,PGC-1α都能以濃度依賴性的方式下調(diào)Hepcidin的本底表達水平,并拮抗LPS和IL-6對Hepcidin的誘導作用。熒光素酶報告基因分析實驗顯示,PGC-1α和HNF4α能協(xié)同抑制Hepcidin啟動子片段(-775～+100)的轉(zhuǎn)錄活性。染色體免疫共沉淀實驗表明,PGC-1α錨定在Hepcidin啟動子的DR-2區(qū)域,并降低該區(qū)域的組蛋白3的乙�；�,從而對抗LPS或IL-6對Hepcidin啟動子的活化效應。在體內(nèi)動物實驗中,我們通過腹腔注射LPS建立了小鼠急性炎癥模型,并配合尾靜脈注射PGC-1α過表達腺病毒的干預手段,使其肝臟特異性高表達PGC-1α�；蚝脱鍖W檢測結(jié)果顯示,LPS顯著抑制PGC-1α和HNF4α的mRNA表達,但刺激hepcidin的表達,小鼠出現(xiàn)明顯的血清鐵缺乏癥狀；而在PGC-1α肝臟特異性過表達的小鼠中,LPS對hepcidin表達的誘導效應被削弱,缺鐵狀況明顯緩解。 綜上所述,PGC-1α是調(diào)控Hepcidin表達和鐵動態(tài)平衡的關(guān)鍵性分子,它能和HNF4α協(xié)同抑制Hepcidin的表達。而在發(fā)生炎癥時,PGC-1α和HNF4α的作用減弱,此時對Hepcidin的抑制解除,Hepcidin的表達和活性升高：最終導致炎性貧血。我們的結(jié)論豐富了現(xiàn)有對炎性貧血發(fā)生機制的理解,并為未來治療鐵異常疾病的藥物開發(fā)提供了新的靶標分子。
[Abstract]:In adults, the iron level in a very fine dynamic balance. If the balance is broken, can lead to iron deficiency or overload, causing a series of diseases. In the dynamic balance of iron ion regulatory mechanisms, Hepcidin plays a crucial role in the.Hepcidin can bind to the key output channel iron ion cell surface Ferroportinl (FPN1), leading to the ubiquitination of FPN1 and lysosomal degradation, thus undermining the expression of dynamic balance of iron ions in.Hepcidin is highly active controllable, fine by many extracellular stimuli such as hypoxia, regulation of endoplasmic reticulum stress and inflammation. It is especially pointed out that the expression of Hepcidin in patients with chronic inflammation than healthy people, resulting in anemia of inflammation (anemia of, inflammation, AI). The only known inflammatory factor IL-6 by STAT-3 ( Signal transduction and activator of transcription-3 signal pathway upregulates Hepcidin expression, but it is still not clear about the mediator between inflammatory stimulation and iron homeostasis.
Transcriptional co activator PGC-1 alpha (peroxisome proliferator activated receptor y coactivator1 alpha) is a regulator of energy metabolism is important, it can selectively and nuclear transcription factors (including HNF4 (hepatic nuclear factor alpha 4 alpha)) interact to activate metabolic pathways downstream. Numerous studies now show that conserved binding sites of Hepcidin the promoter contains HNF4 alpha, alpha and HNF4 in liver specific knockout mice, the expression level of Hepcidin mRNA increased significantly. According to the results of previous research, we find that the inflammatory signal, PGC-1 alpha, alpha HNF4 and Hepcidin between there seems to be inextricably linked, but the signal how specific transduction mechanism?
In order to answer this question, this paper makes research on cell and whole animal level. In vitro experiment, we used PGC-1 alpha overexpression adenovirus infection of HepG2 and HuH7 in human hepatocellular carcinoma cell line, was found both in the transcription or translation level of PGC-1 alpha can with concentration dependent manner and down-regulation of Hepcidin the expression level of LPS and IL-6, and antagonized the induction of Hepcidin. Luciferase reporter gene analysis showed that, PGC-1 alpha and HNF4 alpha inhibition of Hepcidin promoter fragment (-775 ~ +100). The results show that the transcriptional activity of chromatin immunoprecipitation, PGC-1 alpha anchored in the DR-2 region of the Hepcidin promoter, and to reduce the area of histone acetylation level of 3, and against LPS or IL-6 on the activation of the Hepcidin promoter. In in vivo animal experiments, we established acute inflammation in mice by intraperitoneal injection of LPS The model, combined with intravenous injection of PGC-1 alpha overexpression adenovirus intervention, the liver specific expression of PGC-1 alpha gene and serological test results. The expression of LPS showed significant inhibition of PGC-1 alpha and HNF4 alpha mRNA, but stimulated hepcidin expression in mice, significantly serum iron deficiency symptoms; and over expression of PGC-1 in mice liver specific, LPS on the expression of hepcidin induced by iron deficiency condition is weakened, relieved.
In summary, PGC-1 alpha is a key molecule regulating the expression of Hepcidin and iron homeostasis, which can express HNF4 alpha and Hepcidin. The synergistic inhibition of inflammation, decrease of PGC-1 alpha and HNF4 alpha, the inhibition of Hepcidin release, increased Hepcidin expression and activity which leads to anemia of inflammation. We the conclusion enriches the existing on the inflammatory mechanism of anemia in understanding, and provides a new molecular target for future drug development for iron disorders.

【學位授予單位】：南京師范大學
【學位級別】：碩士
【學位授予年份】：2011
【分類號】：R363

【共引文獻】

相關(guān)期刊論文 前5條

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相關(guān)博士學位論文 前2條

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相關(guān)碩士學位論文 前5條

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2 丁芳;多慮平聯(lián)合促紅素治療慢性病貧血的實驗研究[D];遵義醫(yī)學院;2012年

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4 高銀;轉(zhuǎn)鐵蛋白受體在成人急性白血病中的表達及其臨床意義[D];中南大學;2013年

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