La protéine INT6/EIF3E codée par le gène mammalien correspondant au site d’intégration du rétrovirus Mouse Mammary tumor virus (MMTV) n°6 (int-6), a été impliquée dans le cancer du sein chez la souris et l’homme. Malgré qu’INT6 soit une sous-unité du facteur d’initiation de la traduction eIF3, elle n’est pas essentielle pour la traduction générale mais pour l’expression d’ARNm spécifiques tel qu’il a été montré pour la traduction d’ARNm histones. Elle a aussi été impliquée dans la réplication d’ADN en stabilisant le facteur de licence de la réplication MCM7, dans la réponse aux dommages à l’ADN (DDR) et dans la voie du “nonsense-mediated mRNA decay“ (NMD). Par rapport à cette dernière activité j’ai étudié si INT6 pouvait spécifiquement intervenir au niveau de l’homéostasie des télomères en agissant sur les transcrits TERRA. La délétion d’INT6 par une approche d’ARN interférence révèle une augmentation des niveaux des ARN télomériques TERRA qui est dépendante du chromosome et du type cellulaire. Malgré qu’INT6 soit un facteur du NMD, elle n’agit pas sur la demi-vie des TERRA. Les expériences de DNA-FISH ont montré une augmentation des dommages aux télomères (TIF) dans les cellules en absence d’INT6. Les aberrations observées correspondent à des pertes de télomères (TFE) et des signaux multi-télomériques (MTS). Par la technique de digestion de la chromatine à la nucléase micrococcale, nous avons retrouvé une plus rapide accumulation des mono-nucléosomes aux télomères en absence d’INT6, suggérant un rôle dans la conformation de la chromatine télomérique. Ces résultats mettent en évidence INT6 comme un nouveau facteur régulateur de la stabilité des télomères. / The INT6/EIF3E protein encoded by the mammalian integration site 6 (int-6) gene, has been implicated in mouse and human breast carcinogenesis. Although, INT6 is a subunit of the eIF3 translation initiation factor, it is not essential for bulk translation but for specific mRNAs expression as histone mRNA translation. It has also been implicated in DNA replication by stabilizing the DNA replication licensing factor MCM7, in DNA Damage Response (DDR) and in the Nonsense mRNA Decay (NMD) pathway. Relative to the latter activity, I investigated whether INT6 can specifically meddle in telomere homeostasis by acting on TERRA transcripts. Deletion of INT6 by RNA interference approach revealed an increase in the telomeric RNA TERRA levels which is depending on the chromosome and cellular type. Although INT6 is a NMD factor, it doesn’t change TERRA steady-state. DNA-FISH experiments showed an increase in Telomere Induced Foci (TIFs) in INT6 depleted cells. These aberrations correspond to Telomere Free Ends (TFE) and Multi-Telomeric signals (MTS) which implicate INT6 in DDR. By means of Microccocal Nuclease (MNase) mapping assay, we found a rapid accumulation of telomeric mono-nucleosomes in INT6-depleted cells, suggesting a role in telomeric chromatin structure. These findings evidenced that INT6 is a novel key player in telomere stability.

The nucleolus is a multifunctional organelle that, in addition to its primary role in ribosome biogenesis, has emerged as a critical stress sensor and coordinator of stress response. However, the molecular nature of how nucleoli sense stress and coordinate downstream cellular consequence remains poorly understood. NF-κB signalling is a critical regulator of stress response. Many cellular stresses that disrupt nucleolar function also stimulate the NF-κB pathway. However, the role of NF-κB as a downstream effector of nucleolar stress has not yet been examined. Aspirin, a known chemopreventative agent, stimulates the NF-κB pathway to mediate apoptosis but the upstream mechanisms are unclear. In this thesis, I identified a novel nucleolar stress response pathway that culminates in activation of NF-κB signalling, and demonstrated the significance of this nucleolar pathway in the anti-tumour effects of aspirin. Using multiple approaches, I made the novel observations that disruption of the Pol I complex activates the cytoplasmic NF-κB signalling pathway. I show that multiple stress stimuli of NF-κB pathway induce degradation of the crucial Pol I complex component, rDNA transcription initiation factor IA (TIF-IA). I identified the tumour suppressor, p14ARF and the Pol I complex component, upstream binding factor (UBF) as mediators of this degradation. I revealed that inhibition of CDK4 activity lies upstream of UBF/p14ARF-facilitated TIF-IA degradation. Furthermore, using different approaches I show that blocking aspirin/CDK4i-mediated degradation of TIF-IA blocks the effects of these agents on nucleolar morphology and NF-κB signalling. Finally, I show this nucleolar stress response pathway, containing a UBF/p14ARF/TIF-IA axis, is utilized by aspirin to kill colon cancer cells. Taken together, this data presented in this thesis advances understanding of nucleolar stress response, and has therapeutic implications with regard to the anti-tumour effects of aspirin.

No description available.

交通運輸建設與土地開發互為影響，目前台灣交通建設所產生之土地開發效益卻未與公共財務支出連結。導致中央補助出資之交通運輸建設所隱含之「成本」，與伴隨地方發展之土地開發所牽涉之「收益」，形成「中央支出、地方收益」及「地主受益、全民買單」之不公平現象。過去文獻卻仍未就財政面與財務面探討有效之解決機制。 本研究首先檢視區段徵收、工程受益費與都市建設捐等國內財務機制，並引進「稅金增額融資(Tax Increment Financing, TIF)制度」。利用財政努力之公平與效率指標，比較各財務機制，顯示TIF之公平性與效率性皆為最佳。TIF制度為美國地方政府常用之財政、財務自償工具之一。TIF係政府部門透過TIF特區之劃定收取未來價值(value capture)，將未來公共建設與生活環境之投資與改善，所帶來未來稅基增加及稅金增額之結果作為償還交通建設經費之擔保，藉以融資。故TIF係依「專款專用」精神，並利用稅收合理分配方式，將成本與收益確實連結，以達財政與財務自償。 TIF為一財政與財務運用工具，但過去於財政上多運用於都市更新機制，較少運用於公共建設，似乎侷限其功能性；而財務面則甚少探討其TIF特區最適範圍，常逕由申請單位劃定明確範圍，似乎缺乏財務可信度。故本研究選定桃園機場捷運為個案，從財務面探討TIF特區之最適範圍。先以財務模擬，設定基本假設與相關參數，並求得成本與收益項目，以進行財務現金流量分析。而後利用財務比例分析法，進行自償率、投資效益與融資可行性等三項分析。最後再以敏感度分析，求出敏感變數。分析結果顯示納入稅金增額收入後，車站半徑300公尺範圍作為TIF特區範圍A21可達自償；500公尺則A2、A21可達自償；800公尺則A2、A7、A15、A21四個站皆能達到自償。而敏感度分析結果顯示稅金增額收入確為敏感變數之一。本研究利用「時間固定、範圍變動」之自償分析，顯示不同環境變數下，TIF最適範圍亦不同，故應以財務分析方式進行範圍劃定。 最後，本研究根據美國TIF實施經驗，納入最適範圍財務自償分析，建立交通運輸建設TIF財務機制。該機制係將交通運輸建設所造成之土地開發效益，轉化為土地稅稅金增額，並挹注至交通運輸建設成本當中，使計畫能達到自償。未來實施該機制，應著重專責機關建立、執行法制化、民眾觀念建立、稅收分配管理、財務變數之制度與政策設計、財務機制確實運用等面向之執行，使該機制能於國內順利推動，以解決建設財源問題，並期望藉以紓緩地方財政困境。

Methyl bromide (MBr) was widely used as a soil fumigant to manage soilborne pests in plasticulture vegetable production; however, it has been banned by the United Nations Environment Programme. Alternatives to MBr must be implemented to sustain fresh market tomato productivity. Possible MBr alternatives include new fumigant compounds, improved plastic mulch, and grafting. Methyl iodide (MeI) and dimethyl disulfide (DMDS) were tested as fumigant alternatives to MBr for the control of yellow nutsedge and soilborne pathogens of tomato. Virtually impermeable film (VIF) and totally impermeable film (TIF) were tested for fumigant retention and yellow nutsedge control in tomato. Grafting onto resistant rootstocks was tested for bacterial wilt and nematode management in tomato. In the absence of a soil fumigant, TIF suppressed yellow nutsedge better than VIF. TIF increased fumigant retention compared to VIF at similar application rates. Reduced fumigant application rates could be used in combination with TIF while maintaining fumigant concentrations, weed control, and crop yields comparable to greater use rates with VIF. Shank applied DMDS rates could be lowered to 281 L/ha under TIF from 468 L/ha under VIF; shank applied MeI application rates could be reduced to 56 L/ha under TIF compared to 93 L/ha under VIF and drip applied DMDS could be reduced from 561 L/ha under VIF film to 374 L/ha under TIF. Grafting susceptible commercial tomato cultivars onto resistant tomato hybrid rootstocks increased yields and plant survival in bacterial wilt infested fields. "Cheong Gang", "BHN 998", and "BHN 1054" were the best performing rootstocks for bacterial wilt resistance and tomato fruit yield in severely infested fields. Grafting increased tomato yield and decreased root galling from root-knot nematodes in an infested field. Hybrid rootstock "RST 106" resulted in the lowest root-knot nematode galling. In conclusion, TIF with reduced rates of DMDS or MeI is a viable MBr alternative for fresh market tomato production to retain effective doses of fumigant, manage yellow nutsedge and maintain yields. Grafting is an effective MBr alternative to manage bacterial wilt and root-knot nematode and maintain tomato yields. / Ph. D.

No description available.

No description available.