本文選題：AD + 內(nèi)質(zhì)網(wǎng)應激�。� 參考：《華中科技大學》2012年博士論文

【摘要】：老年癡呆,又稱為阿爾茨海默病(Alzheimer's Disease, AD)是一種進行性發(fā)展的神經(jīng)退行性疾病,其臨床表現(xiàn)為認知能力下降、記憶功能降低甚至喪失。隨著老齡社會的到來,患阿爾茨海默病的病人會越來越多,給社會和家庭帶來沉重的經(jīng)濟負擔。AD病人腦中兩大病理學特征是：神經(jīng)元外由Aβ短肽形成的老年斑(Senile plaques,SP)的沉積；神經(jīng)元內(nèi)神經(jīng)纖維纏結(jié)(Neurofibrillary tangles, NFTs)的聚集。神經(jīng)纖維纏結(jié)是由過度磷酸化的tau蛋白構(gòu)成。并且研究發(fā)現(xiàn),由過度磷酸化的tau蛋白形成的NTFs的數(shù)量和AD病人的臨床癡呆程度成正相關(guān)。 內(nèi)質(zhì)網(wǎng)(Endoplasmic reticulum, ER)是真核細胞中最重要的細胞器之一,主要參與維持胞內(nèi)鈣穩(wěn)態(tài)以及新合成的膜蛋白和分泌型蛋白質(zhì)的翻譯后處理過程。多種病理條件,如缺血、缺氧或中毒等刺激下,誘導細胞發(fā)生以伴侶蛋白表達及非折疊蛋白反應啟動為特征的內(nèi)質(zhì)網(wǎng)應激(ER Stress)。有很多研究報道稱ER應激參與了AD的發(fā)病過程,但具體機制有待深入研究。內(nèi)質(zhì)網(wǎng)分子伴侶(ER molecular chaperones) Bip (Immunoglobulin-binding protein)是內(nèi)質(zhì)網(wǎng)中最重要的分子伴侶之一,在內(nèi)質(zhì)網(wǎng)應激時表達增高,被認為是內(nèi)質(zhì)網(wǎng)應激時最重要的標志之一。Bip在AD病人的大腦皮質(zhì)和海馬中表達明顯增高；本課題組以前研究發(fā)現(xiàn)持續(xù)光照會造成大鼠海馬中Bip水平增高,tau蛋白過度磷酸化。Bip與tau過度磷酸化之間的關(guān)系及相關(guān)機制尚無報道。 糖原合酶激酶-3β(Glycogen synthase kinase-3p, GSK-3p)是在AD發(fā)病過程中促使tau蛋白發(fā)生過度磷酸化的最重要的磷酸激酶之一,在AD病人腦中GSK-3β過度激活。本課題前期研究發(fā)現(xiàn),ER應激在誘導Bip水平增高、tau蛋白過度磷酸化的同時,激活了GSK-3β;有研究發(fā)現(xiàn),在突變Bip的轉(zhuǎn)基因小鼠中,Bip失去正常功能作用的同時,GSK-3β活性受也到了抑制,上述研究提示Bip和GSK-3β也可能存在著某些必然的聯(lián)系,但是具體機制不清楚。 因此,本研究利用ER應激誘導劑毒胡蘿卜素(Thapsigargin, TG)在整體或細胞水平誘導ER應激,發(fā)現(xiàn)GSK-3β激活、tau在Ser396、Ser198/199/202位點發(fā)生過度磷酸化；抑制GSK-3β激活,tau磷酸化水平顯著降低。進一步利用RNA干擾技術(shù)下調(diào)Bip水平,TG誘導的tau過度磷酸化顯著降低；ER應激及Bip過表達時,Bip可激活GSK-3β、促進GSK-3β與tau特異性結(jié)合而誘導tau過度磷酸化。核酸交換因子(Nucleotide exchange factor) Sil1是Bip的重要的共同伴侶分子。本研究發(fā)現(xiàn)在ER應激、Bip過表達的細胞中及AD模型小鼠(Tg2576小鼠)腦中Sil1表達明顯降低,在細胞水平過表達Sil1通過抑制GSK-3β激活、減少Bip與GSK-3β、tau結(jié)合而顯著改善TG和Bip過表達誘導的tau過度磷酸化；下調(diào)Sil1則Bip水平增高及tau發(fā)生過度磷酸化。此外,在培養(yǎng)的大鼠原代海馬神經(jīng)元過表達Bip或下調(diào)Sill水平,神經(jīng)元的軸突生長明顯抑制。 本研究系統(tǒng)證明了Bip可通過激活GSK-3β、促進GSK-3β與tau特異性結(jié)合而誘導tau過度磷酸化,Sil1對ER應激及Bip過表達誘導的tau蛋白過度磷酸化具有保護作用。研究結(jié)果為進一步認識內(nèi)質(zhì)網(wǎng)相關(guān)的分子伴侶在AD發(fā)病中的作用及防治研究提供了依據(jù)。
[Abstract]:Alzheimer's disease, also known as Alzheimer's Disease (AD), is a progressive neurodegenerative disease. Its clinical manifestation is a decline in cognitive ability and a decrease in memory function. With the arrival of an aging society, patients with Alzheimer's disease are becoming more and more serious, bringing heavy economic burden to society and families. The two major pathological features in the brain of.AD patients are: the deposition of Senile plaques (SP) formed by A beta short peptide in neurons; aggregation of Neurofibrillary tangles, NFTs in neurons. The neurofibrillary tangles are constructed from the overphosphorylated tau protein. And the study found that the tau protein form is overphosphorylated. The number of NTFs was positively correlated with the degree of dementia in AD patients.
Endoplasmic reticulum (ER) is one of the most important organelles in eukaryotic cells. It is mainly involved in the maintenance of intracellular calcium homeostasis and the post-processing of newly synthesized membrane proteins and secretory proteins. A variety of pathological conditions, such as ischemia, hypoxia or poisoning, induce cells to occur with chaperone protein expression and unfolded eggs. A number of studies have reported that ER stress is involved in the pathogenesis of AD, but the specific mechanisms need to be studied in depth. The specific mechanisms need to be further studied. The endoplasmic reticulum molecular chaperone (ER molecular chaperones) Bip (Immunoglobulin-binding protein) is one of the most important molecular chaperones in the endoplasmic reticulum and is stressed by endoplasmic reticulum. The high expression of.Bip is considered to be one of the most important markers of endoplasmic reticulum stress. The expression of.Bip in the cerebral cortex and hippocampus of AD patients is significantly higher. The previous study found that the continuous light irradiation caused the increase of Bip in the hippocampus of rats, and the relationship between the excessive phosphorylation of tau protein and the phosphorylation of tau over the hippocampus and the related mechanisms. Report.
The glycogen synthase kinase -3 beta (Glycogen synthase kinase-3p, GSK-3p) is one of the most important phosphorylation of tau protein in the pathogenesis of AD. GSK-3 beta in the brain of AD patients is excessively activated. The previous study found that ER stress was induced by the increase of Bip level and the activation of tau protein over phosphorylation. It has been found that in transgenic mice with mutant Bip, Bip lost normal function and GSK-3 beta activity was also inhibited. The above studies suggest that Bip and GSK-3 beta may also have certain connections, but the specific mechanism is not clear.
Therefore, this study uses ER stress inducer (Thapsigargin, TG) to induce ER stress at the whole or cell level. It is found that GSK-3 beta activates, tau is over phosphorylated at Ser396, Ser198/199/202 site, and GSK-3 beta activation, and tau phosphorylation level is reduced significantly. Further downregulation of Bip level by RNA interference technique is used. Over expression of ER stress and Bip overexpression, Bip activates GSK-3 beta, promotes GSK-3 beta and tau specific binding and induces tau overphosphorylation. Nucleic acid exchange factor (Nucleotide exchange factor) Sil1 is the important co chaperone of Bip. In 576 mice, the expression of Sil1 in the brain was obviously reduced. The overexpression of Sil1 in the cell level by inhibiting the activation of GSK-3 beta, reducing the combination of Bip and GSK-3 beta, tau to significantly improve the tau overexpression induced by TG and Bip overexpression, and down regulated Sil1 Bip level and tau occur over phosphorylation. In addition, the primary hippocampal neurons in the cultured rat were overexpressed. Or down regulation of Sill, the axonal growth of neurons was significantly inhibited.
This study shows that Bip can induce the excessive phosphorylation of tau by activating GSK-3 beta and promoting the specific binding of GSK-3 beta to tau. Sil1 has protective effect on ER stress and the excessive phosphorylation of tau protein induced by Bip overexpression. The research results provide a further understanding of the role of endoplasmic reticulum related partners in the pathogenesis of AD and the prevention and treatment of AD. It's the basis.

【學位授予單位】：華中科技大學
【學位級別】：博士
【學位授予年份】：2012
【分類號】：R749.16

【共引文獻】

相關(guān)期刊論文 前3條

1 吳小忠;楊民;郭嚴;孫軍;;sorafenib對裸鼠肝癌術(shù)后復發(fā)的抑制和促凋亡的實驗研究[J];醫(yī)學研究生學報;2010年12期

2 代景友;韓卓越;王書;張新晨;;葡萄糖調(diào)節(jié)蛋白78在肝癌中的研究進展[J];中國現(xiàn)代普通外科進展;2012年11期

3 吳小忠;楊民;;Sorafenib治療進展期原發(fā)性肝癌[J];實用臨床醫(yī)藥雜志;2010年17期

相關(guān)博士學位論文 前1條

1 方穎;去泛素化酶UCH37對肝癌復發(fā)的影響及其分子機制研究[D];復旦大學;2012年

，

本文編號：1807648