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標題: | 脫氧核糖核酸甲基化修飾重塑在白色念珠球菌的表型依賴費洛蒙反應中具有關鍵的表觀遺傳調控作用 DNA Methylation Remodeling in Candida albicans Might Play a Key Role in Epigenetic Regulation of Phenotype- Dependent Pheromone Responses |
作者: | Sin-Yong Hoo 何新榮 |
指導教授: | 林晉玄(Ching-Hsuan Lin) |
關鍵字: | 白色念珠菌,white-opaque 表現型轉換,細胞依賴型費洛蒙反應,Cph1,5-azacytidine,white 細胞費洛蒙反應基因,opaque 細胞費洛蒙反應基因,DNA 甲基化重塑,專一位點 DNA 甲基化模型, Candida albicans,white-opaque switching,phenotype-dependent pheromone responses,Cph1,5-azacytidine,white response genes,opaque response genes,DNA methylation remodeling,site-specific DNA methylation patterns, |
出版年 : | 2017 |
學位: | 碩士 |
摘要: | 白色念珠菌(Candida albicans)是醫院感染中最常見的伺機性真菌病原體,主要感染的宿主為免疫缺陷病人,並可能造成全身性感染。由於白色念珠菌具有獨特的型態可塑性(phenotypic plasticity),使其能夠適應宿主多種不同環境。在白色念珠球菌的型態可塑性中,white 和 opaque 細胞之間的型態轉換,稱為 white-opaque 表現型轉換。其中,opaque 細胞具有交配能力,而且能夠分泌費洛蒙促進 opaque 細胞產生交配突觸,稱為 opaque 細胞費洛蒙反應。除此之外,opaque 細胞分泌的費洛蒙還可以刺激不具交配能力的 white 細胞形成性生物膜(sexual biofilm),幫助維持 opaque 細胞分泌的費洛蒙在空間上的濃度梯度,稱為 white 細胞費洛蒙反應。在 white 和 opaque 細胞費洛蒙反應中,最有趣的是 white 和 opaque 細胞都是透過相同的費洛蒙訊息傳遞路徑和主要的轉錄因子 Cph1 來感受費洛蒙的刺激, 但在 white 和 opaque 細胞中卻分別有著不同的細胞依賴型費洛蒙反應基因(phenotype-dependent response genes)被促進,併產生不同細胞依賴型費洛蒙反應(phenotype-dependent pheromone response)。因此, white 和 opaque 細胞中可能存在不同的關鍵因子,進一步輔助費洛蒙訊息傳遞路徑和 Cph1 在 white 和 opaque 細胞之間專一的調控細胞依賴型費洛蒙反應基因的表現和細胞依賴型費洛蒙反應。根據前人的研究指出 DNA 甲基化修飾在不同細胞型態的白色念珠菌之間可以有效的調節不同基因的表達。在此,我們假設DNA 甲基化可能在細胞依賴型費洛蒙反應的調控中扮演一個重要的角色。結果顯示,在AzaC(5-azacytidine, DNA 甲基化抑制劑)處理下使 DNA 去甲基化後, white 細胞的費洛蒙反應受到了抑制,與其表現量下降的 white 細胞費洛蒙反應基因(EAP1 和 PBR1)有關。反之,opaque 細胞費洛蒙反應基因(FUS1 和 FIG1)的表現量在 DNA 去甲基化後有明顯的上升,併進一步促進了 opaque 細胞費洛蒙反應。除此之外,全基因組亞硫酸鹽定序(whole genomic bisulfite sequencing)和 RNA 定序的結果顯示,細胞依賴型費洛蒙反應基因的調控存在 DNA 去甲基化和DNA重新甲基化(de novo DNA methylation)的過程,稱為DNA甲基化重塑(DNA methylation remodeling)。在細胞依賴型費洛蒙反應中,DNA甲基化重塑產生不同的專一位點 DNA甲基化模型(site-specific DNA methylation patterns)與精確調節不同的細胞依賴型費洛蒙反應基因有著關聯。因此,我們推測在費洛蒙刺激下的白色念珠菌中,DNA甲基化重塑對於細胞依賴型費洛蒙反應的調控有著關鍵的作用。 Candida albicans is most frequently isolated fungal pathogen in nosocomial infections, which is an opportunistic fungal pathogen that infect immunodeficiency patient. Phenotypic plasticity enables C. albicans adapts easily to different niche of immunocompromised patients, causing lethal systemic infections. A heritable and reversible phenotypic switching between white and opaque cells, called white-opaque switching. Herein, mating competent opaque cells secrete sexual pheromone to promote opaque cell mating projection, called opaque cell response. Besides, the pheromone can also stimulate sexual biofilm formation of mating incompetent white cells, named white cell response, which in turn effectively maintain the spatial pheromone gradient. Interestingly, white and opaque cells are sharing the same pheromone signaling pathway and major transcription factor Cph1 despite having different cell specific response and gene expression during pheromone stimulation. Thus, there may have crucial epigenetic regulation which contribute to the pheromone signaling pathway and Cph1 for regulating different cell specific response genes in white and opaque cells. According to the previous research, DNA methylation efficiently regulates expression of cell specific gene between different cell types of C. albicans. Here, we hypothesized that DNA methylation might contribute to the regulating of phenotype-dependent pheromone responses. Indeed, the results of AzaC (5-azacytidine, DNA methylation inhibitor) treatment show that DNA demethylation inhibits white cell response, which is associated with downregulated white response genes (EAP1 and PBR1). By contrast, opaque cell response is promoted by DNA demethylation, raised by upregulated opaque response genes (FUS1 and FIG1). Also, whole genomic bisulfite sequencing and RNA sequencing data further indicate that a process includes critical DNA demethylation and de novo DNA methylation, called DNA methylation remodeling. DNA methylation remodeling generates various site-specific DNA methylation patterns during phenotype-dependent pheromone responses, relating to accurately regulate cell specific response genes in white and opaque cells. Therefore, we hypothesis that DNA methylation remodeling in C. albicans, which may play a key role in contributing to regulate phenotype-dependent pheromone responses. |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/70172 |
DOI: | 10.6342/NTU201702488 |
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顯示於系所單位: | 生化科技學系 |
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