Diss. (sammanfattning) Göteborg : Göteborgs universitet, 2010. / Härtill 3 uppsatser.

Cilia are evolutionarily conserved microtubule-based organelles projecting from nearly all vertebrate cells, and ciliary defects result in a variety of human disorders known as ciliopathies. Recent studies have shown that several planar cell polarity (PCP) proteins are essential for cilia functions. Here, we focused on Fritz, known as a novel PCP effector protein in Drosophila, in multi-ciliated cells in the epidermis of Xenopus laevis embryos. To investigate the role of Fritz, using confocal and scanning electron microscopy, we discovered that Fritz localizes along the ciliary axonemes and that knockdown of Fritz causes severe reductions in both axoneme length and number. Then, using pull-downs and mass-spectrometry, we identified Chaperonin Containing T-complex polypeptide 1 (CCT) and septin as interacting partners of Fritz. CCT is the key chaperonin interacting with septins, and both have been implicated in ciliogenesis. Using tagged CCT subunit constructs, we found that the tagged CCTα and CCTε co-localize with Fritz along the ciliary axonemes of multi-ciliated cells. Knockdown of Fritz resulted in the accumulation of CCT at the apical cytoplasm of multi-ciliated cells; however, it was confirmed that Fritz does not affect the CCT holoenzyme assembly. Septins, another interacting partner of Fritz, are novel cytoskeletal elements. Using septin antibodies, we found that endogenous septins also localize along the ciliary axonemes and accumulate in the apical cytoplasm of multi-ciliated cells in Fritz morphants. Similar ciliary defects were observed in septin morphants. Our results reveal that Fritz is essential for ciliogenesis, and that CCT and septin interact with Fritz to control ciliogenesis in Xenopus multi-ciliated cells. Additionally, tubulin acetylation is markedly reduced by Fritz knockdown, suggesting that Fritz affects tubulin acetylation.

Phosducin-like protein (PhLP) binds G-protein beta gamma subunits and is thought to assist in assembly of the G-protein beta gamma dimer. Phosphorylation of PhLP at serine residues 18-20 by the casein kinase 2 (CK2) appears to play an essential role in this process. PhLP has also been shown to interact with the chaperonin containing TCP-1 (CCT) atop its apical domain, not entering the substrate folding cavity. However, the physiological role of the PhLP-CCT interaction in G-protein beta gamma dimer formation remains unclear. This study addresses the mechanism of G-protein beta gamma assembly by exploring the specific roles of CCT and CK2 phosphorylation of PhLP in the assembly process. Both overexpressed and endogenous Gbeta were shown to co-immunoprecipitate with CCT to a similar extent as PhLP, indicating that CCT may be involved in the folding of Gbeta. In addition, Ggamma overexpression enhanced the binding of PhLP to CCT, suggesting the formation of a ternary PhLP-Gbeta-CCT complex. In contrast, overexpression of PhLP caused the release of G-beta from CCT. This release was blocked by a PhLP S18-20A variant that lacks the S18-20 CK2 phosphorylation site. PhLP S18-20A has been previously shown to negatively affect the G-protein beta gamma dimer formation, suggesting a correlation between PhLP-mediated release of Gbeta from CCT and G protein beta gamma assembly. Experiments investigating the role of Ggamma in this process show that Ggamma does not interact with CCT nor is it the essential factor in the release of Gbeta from CCT. A new model is therefore proposed for the G-protein beta gamma subunits' assembly involving the formation of a PhLP-Gbeta-CCT ternary complex followed by the release of a phosphorylated PhLP-Gbeta complex from CCT. In the PhLP-Gbeta complex, the Ggamma binding face of Gbeta is exposed, allowing for the formation of the G-protein beta gamma dimer.

TCP-1是一种新型的定向于肿瘤血管的多肽，通过小鼠体内的噬菌体展示技术筛选得到。在之前的研究中，我们已证明TCP-1具有定向于肿瘤血管并有效靶向运输抗肿瘤药物和显像剂的特性。本研究的目的是进一步研究在原位结肠癌模型中定向运输抗肿瘤药物肿瘤坏死因子(TNFα)，以及在结肠癌临床样本中运输显像剂异硫氰酸荧光素(FITC)的能力。并对TCP-1与肿瘤坏死因子的融合蛋白TCP-1/TNFα的抗肿瘤机制进行阐述。 / 本研究中，我们首先尝试用TCP-1作为载体，将增强绿色荧光蛋白靶向运输至肿瘤血管。结果证明TCP-1可以成功将蛋白运输到在肿瘤血管而非其它正常的组织器官上。TCP-1还可以靶向运输肿瘤坏死因子并增强其抗肿瘤作用。和肿瘤坏死因子比较，融合蛋白TCP-1/TNFα处理组的凋亡细胞数量增多，肿瘤微血管数目减少，并且无明显毒副作用。与结肠癌的一线化疗药物5-氟尿嘧啶(5-FU)联合给药后，与TNFα与5-FU联合给药相比较，融合蛋白TCP-1/TNFα联合5-FU在以下方面具有更明显的作用：抑制肿瘤生长，增加肿瘤细胞凋亡和抑制肿瘤细胞增殖，促进肿瘤血管正常化，升高瘤内免疫细胞以及减轻骨髓和脾内的免疫抑制反应。经检测TCP-1的靶向运输增加了瘤内的TNFα以及5-FU的浓度。这些都表明TCP-1不但可以靶向运输TCP-1/TNFα至肿瘤血管，还可以增加CD8+细胞的浸润增加瘤内免疫反应以及增加血管对抗肿瘤药物的通透性。以上都对抗肿瘤起到重要作用。 / 在临床的结肠癌样本中，TCP-1对肿瘤血管的结合能力也得到了证实。48.98%的结肠癌样本对TCP-1的结合为阳性。统计学分析显示TCP-1的结合与结肠癌的分期和肿瘤位置有关，对于N2期，位于乙状结肠的肿瘤的结合尤为明显。本研究的主要目的是将分离鉴定出的TCP-1发展成为结肠癌的生物标记，并且作为运输抗肿瘤药物和显像剂的载体应用于结肠癌的诊断和治疗中。鉴于TCP-1的靶向运输特点，将会有机会研发更多的抗肿瘤药物，同时增强传统化疗药的抗肿瘤作用。这些都可以优化肿瘤治疗的方案。综上所述，TCP-1是一种在结肠癌治疗诊断中具有广阔前景的多肽。 / TCP-1 is a novel vasculature-targeting peptide. It was discovered through the in vivo phage library selection in mice. It was demonstrated that TCP-1 peptide exhibited a homing ability to the neovasculature of colon tumors and was capable of efficiently delivering imaging agents and chemotherapeutic drugs to this target site. The current study is to further investigate the targeting ability of TCP-1 to deliver a known immunomodulator, tumor necrosis factor α (TNFα) as an example of anti-cancer drug in an orthotopic colorectal cancer (CRC) model and fluorescein isothiocyanate (FITC) as imaging agent for testing the binding capacity for tumors in colorectal cancer patients. The mechanisms for the action of this novel biologic TCP-1/TNFα in the treatment of colon cancer in mice were also defined. / In this study, we observed that TCP-1 peptide delivered enhanced green fluorescent protein (EGFP) only to tumor blood vessel other than normal organs after TCP- 1/EGFP injection. This was not observed after EGFP injection. This finding showed that TCP-1 can deliver biologic protein to the tumor blood vessels. Furthermore, results from TNFα or TCP-1/TNFα targeted delivery experiments showed that TCP- 1/TNFα displayed stronger anti-cancer effects than TNFα alone on the induction of apoptosis and reduction in number of microvessels in the tumors, without significant effect in systemic toxicity. In the combined therapy with 5-fluorouracil (5-FU), a standard drug for colon cancer treatment, pretreatment with low dose (1 ng TNFα /mouse) of TNFα or TCP-1/TNFα potentiated the anti-cancer action of 5-FU. In this regard, TCP-1/TNFα could significantly reduce tumor size and weight, increase number of apoptotic cells, inhibit tumor cell proliferation, normalize tumor blood vessels, facilitate infiltration of immune cells to tumor mass and attenuate immunosuppression in bone marrow and spleen. Moreover, TCP-1 could significantly increase intratumoral levels of TNFα and 5-FU. It was also suggested that TCP-1 could selectively deliver TNFα to the tumor blood vessels and modulate the immune response by increasing CD8+ cells infiltration to tumors and increase vascular permeability to 5-FU. These observations may be the key actions to reduce tumor growth. / The binding ability of TCP-1 was also detected in clinical samples from colorectal cancer patients in which 24/49 (48.98%) tumor tissues were positive with TCP-1 binding signal. Statistical analysis showed that TCP-1 had a strong and significant binding with colorectal cancer at the N2 stage among the different colorectal cancer stages (P=0.028) and location in the colon at the sigmoid (P<0.001). / Our study also focused on the isolation and identification of the binding molecule of TCP-1 in order to develop it into a biomarker for CRC and using TCP-1 as a carrier in delivering anti-cancer drugs and imaging agents to colon tumors for cancer therapy and diagnosis. With the homing property of TCP-1 on colon tumor blood vessels, new types of anti-cancer drugs will be developed and their combinations with conventional chemotherapy drugs will optimize the therapeutic outcome and improve regimen of treatment for CRC. Taken together, TCP-1 peptide appears to be a promising agent in molecular imaging and drug delivery for CRC diagnosis and therapy. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Lu, Lan. / Thesis (Ph.D.) Chinese University of Hong Kong, 2014. / Includes bibliographical references (leaves 157-177). / Abstracts also in Chinese. / Lu, Lan.