新孢子蟲激活宿主EGFR信號轉導調控細胞凋亡的分子機制
發(fā)布時間：2019-03-17 13:54
【摘要】：犬新孢子蟲(Neospora caninum)屬于頂復門,是一種專門寄生于哺乳宿主細胞內的致病性原蟲。它能感染大多數哺乳類動物,其中對牛的危害最為嚴重。肉�；蚰膛８腥綨.caninum主要引起流產,給全世界養(yǎng)牛業(yè)帶來巨大的經濟損失。然而,N.caninum的細胞感染機制還沒有被完全闡明,尤其N.caninum對宿主信號轉導和細胞生存或死亡的調控機制報道甚少。EGFR(epidermal growth factor receptor)通路是參與細胞存活調控的重要信號通路。已經有報道弓形蟲能夠抑制感染細胞的凋亡;弓形蟲感染激活EGFR-AKT信號通路,抑制自噬蛋白對蟲體的靶標和殺傷作用。但在新孢子蟲,是否其感染能夠調控EGFR信號報道較少,能否通過EGFR信號轉導控制宿主細胞的凋亡仍未知。因此,在本文中我們將針對N.caninum對宿主EGFR信號轉導通路及細胞凋亡調控的分子機制作詳細的研究,論文包括以下幾個部分:1.通過對新孢子蟲刺激后宿主EGFR通路信號蛋白和凋亡相關蛋白的表達檢測,結果表明N.caninum感染能迅速激活宿主EGFR、EGFR-AKT和EGFR-MAPK信號通路,進而調控凋亡相關蛋白的表達;2.通過對細胞凋亡相關指標的檢測,評估新孢子蟲感染對宿主細胞活力和細胞凋亡的影響。結果發(fā)現,N.caninum感染早期能夠抑制細胞凋亡,且其對凋亡的抑制主要通過EGFR-AKT通路的活化介導;3.對新孢子蟲激活EGFR信號轉導和抑制細胞凋亡的分子機制進行了探討,結果發(fā)現N.caninum通過EGF-MIC和宿主細胞表面EGF受體的互作,激活宿主EGFR信號轉導,進而抑制細胞凋亡;4.使用特異性抑制劑、siRNA阻斷和干預宿主EGFR通路后,對新孢子蟲細胞感染的影響進行了檢測,結果表明抑制EGFR信號通路的活化或沉默EGFR、AKT后,新孢子蟲的細胞感染被顯著抑制;總之,本研究對新孢子蟲調控細胞凋亡的分子機制進行了探討,結果發(fā)現:N.caninum感染能夠抑制宿主細胞凋亡,并且其對凋亡的抑制是通過含EGF樣結構域的微線蛋白(EGF-MIC)來發(fā)揮作用的,N.caninum MIC-EGF通過與宿主EGFR的互作,介導EGFR-AKT信號通路的活化,并進一步調控凋亡相關蛋白的表達,結果發(fā)揮抑制細胞凋亡的效應。這些新的信息將有助于我們更深入地認識EGFR信號轉導在蟲體感染過程中的功能及新孢子蟲的細胞感染和生存機制;為新孢子蟲參與宿主功能的調控提供了理論依據,對今后尋找和設計用于化學干預新孢子蟲病的有效藥物具有重要意義。
[Abstract]:Neosporidium canis (Neospora caninum) is a kind of pathogenic protozoa that parasitize the host cells of lactation. It can infect most mammals, among which the most serious harm to cattle. Beef cattle or cows infected with N.caninum mainly cause abortion and bring huge economic losses to cattle industry all over the world. However, the mechanism of N.caninum cell infection has not been fully clarified. In particular, there are few reports on the regulation of host signal transduction and cell survival or death by N.caninum. EGFR (epidermal growth factor receptor) pathway is an important signal pathway involved in the regulation of cell survival. It has been reported that Toxoplasma gondii can inhibit the apoptosis of infected cells and that Toxoplasma gondii infection activates EGFR-AKT signaling pathway and inhibits the target and killing effect of autophagy protein on infected cells. However, in Neosporidium, whether the infection can regulate the EGFR signal is less reported, whether the EGFR signal transduction can control the apoptosis of host cells is still unknown. Therefore, in this paper, we will make a detailed study of the molecular mechanism of N.caninum on the host EGFR signal transduction pathway and apoptosis regulation. The thesis includes the following parts: 1. After stimulation with neosporidium, the expression of EGFR signaling protein and apoptosis-related protein in host was detected. The results showed that N.caninum infection could activate the EGFR,EGFR-AKT and EGFR-MAPK signaling pathway of host rapidly, and then regulate the expression of apoptosis-related protein. 2. The effect of Neosporidium infection on cell viability and apoptosis was evaluated by detecting apoptosis-related indexes. The results showed that N.caninum infection could inhibit apoptosis in early stage, and its inhibition was mainly mediated by activation of EGFR-AKT pathway. The molecular mechanism of neosporidium activating EGFR signal transduction and inhibiting cell apoptosis was discussed. The results showed that N.caninum could activate host EGFR signal transduction through interaction between EGF-MIC and host cell surface EGF receptor, and then inhibit cell apoptosis; 4. The effects of siRNA on Neosporidium cell infection were detected after blocking and interfering the host EGFR pathway with specific inhibitors. The results showed that after inhibiting the activation of EGFR signaling pathway or silencing EGFR,AKT, the cell infection of Neosporidium was significantly inhibited. In conclusion, this study discussed the molecular mechanism of neosporidium regulating cell apoptosis. The results showed that N.caninum infection could inhibit the apoptosis of host cells. The inhibition of apoptosis is mediated by the EGF-like domain EGF-MIC, which mediates the activation of the EGFR-AKT signaling pathway by interacting with the host EGFR. And further regulate the expression of apoptosis-related proteins, resulting in the inhibition of cell apoptosis effect. These new information will help us to further understand the function of EGFR signal transduction in the process of parasite infection and the cell infection and survival mechanism of Neosporidium. It provides a theoretical basis for neosporidium to participate in the regulation of host function, and it is of great significance to find and design effective drugs for chemical intervention of neosporidiosis in the future.
【學位授予單位】：吉林大學
【學位級別】：博士
【學位授予年份】：2017
【分類號】：S852.7
本文編號：2442363
[Abstract]:Neosporidium canis (Neospora caninum) is a kind of pathogenic protozoa that parasitize the host cells of lactation. It can infect most mammals, among which the most serious harm to cattle. Beef cattle or cows infected with N.caninum mainly cause abortion and bring huge economic losses to cattle industry all over the world. However, the mechanism of N.caninum cell infection has not been fully clarified. In particular, there are few reports on the regulation of host signal transduction and cell survival or death by N.caninum. EGFR (epidermal growth factor receptor) pathway is an important signal pathway involved in the regulation of cell survival. It has been reported that Toxoplasma gondii can inhibit the apoptosis of infected cells and that Toxoplasma gondii infection activates EGFR-AKT signaling pathway and inhibits the target and killing effect of autophagy protein on infected cells. However, in Neosporidium, whether the infection can regulate the EGFR signal is less reported, whether the EGFR signal transduction can control the apoptosis of host cells is still unknown. Therefore, in this paper, we will make a detailed study of the molecular mechanism of N.caninum on the host EGFR signal transduction pathway and apoptosis regulation. The thesis includes the following parts: 1. After stimulation with neosporidium, the expression of EGFR signaling protein and apoptosis-related protein in host was detected. The results showed that N.caninum infection could activate the EGFR,EGFR-AKT and EGFR-MAPK signaling pathway of host rapidly, and then regulate the expression of apoptosis-related protein. 2. The effect of Neosporidium infection on cell viability and apoptosis was evaluated by detecting apoptosis-related indexes. The results showed that N.caninum infection could inhibit apoptosis in early stage, and its inhibition was mainly mediated by activation of EGFR-AKT pathway. The molecular mechanism of neosporidium activating EGFR signal transduction and inhibiting cell apoptosis was discussed. The results showed that N.caninum could activate host EGFR signal transduction through interaction between EGF-MIC and host cell surface EGF receptor, and then inhibit cell apoptosis; 4. The effects of siRNA on Neosporidium cell infection were detected after blocking and interfering the host EGFR pathway with specific inhibitors. The results showed that after inhibiting the activation of EGFR signaling pathway or silencing EGFR,AKT, the cell infection of Neosporidium was significantly inhibited. In conclusion, this study discussed the molecular mechanism of neosporidium regulating cell apoptosis. The results showed that N.caninum infection could inhibit the apoptosis of host cells. The inhibition of apoptosis is mediated by the EGF-like domain EGF-MIC, which mediates the activation of the EGFR-AKT signaling pathway by interacting with the host EGFR. And further regulate the expression of apoptosis-related proteins, resulting in the inhibition of cell apoptosis effect. These new information will help us to further understand the function of EGFR signal transduction in the process of parasite infection and the cell infection and survival mechanism of Neosporidium. It provides a theoretical basis for neosporidium to participate in the regulation of host function, and it is of great significance to find and design effective drugs for chemical intervention of neosporidiosis in the future.
【學位授予單位】：吉林大學
【學位級別】：博士
【學位授予年份】：2017
【分類號】：S852.7
【相似文獻】
相關博士學位論文 前1條
1 靳小霞;新孢子蟲激活宿主EGFR信號轉導調控細胞凋亡的分子機制[D];吉林大學;2017年
，本文編號：2442363
本文鏈接：http://sikaile.net/shoufeilunwen/nykjbs/2442363.html
最近更新
教材專著
