Braun, Till Jonas (2023). Patterns of micro-RNAs, their target pathways, and non-canonical functions of miR regulating proteins in T-prolymphocytic leukemia. PhD thesis, Universität zu Köln.
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Abstract
T-prolymphocytic leukemia (T-PLL) is an aggressive and refractory mature T-cell neoplasm with currently very limited therapeutic options. The current disease concept is centered around cooperative perturbations of TCL1A and ATM, leading to enhanced T-cell receptor signaling as well as aberrant DNA repair mechanisms. We recently described recurrent gains on chromosome 8q, that frequently involve the AGO2 gene. In a variety of malignancies, AGO2 was assigned an oncogenic role by mediating microRNA (miR) processing. Here, we present an integrated multi-level dataset of 46 T-PLL patients, demonstrating overexpression of AGO2 in a majority of T-PLL cases. This overexpression was associated with a larger tumor burden as well as a higher proliferation capacity in vitro, indicating an oncogenic role of AGO2 in the leukemogenesis of T-PLL. In addition to pro-oncogenic miR-ome/transcriptome networks shaped by AGO2, we demonstrate a previously undescribed relationship between TCR signaling and AGO2. In-vitro systems of transiently modulated AGO2 protein expression demonstrated an enhancing role of AGO2 on the phosphor-activation of the TCR upstream-kinases ZAP70, PLCγ1, and LAT. Notably, these effects were mediated by direct protein-protein interactions, as shown by interactions with LCK and ZAP70 in global mass-spectrometry analysis and proximity ligation assays in TCR-activated cells. Subsequent models of three-dimensional structures revealed a membranous protein complex formation, requiring post-transcriptional modifications of AGO2 by LCK. In addition to a global perturbation of the ‘miR-master regulator’ AGO2, we showed a T-PLL specific miR expression signature, consisting of 34 miRs, which presented a differential expression in T-PLL compared to pan T-cells of age-matched healthy donors. Importantly, these miR signatures revealed the influence of constitutive TCR activation. Most prominently, two major subgroups of T-PLL cases were defined by the expression of the miR-141 and miR-200c cluster. In addition, more aggressive presentations of T-PLL were associated with increased expression of miR-223-3p and reduced expression of miR-21 as well as the miR-29 cluster. In an integrative approach of miR as well as mRNA sequencing, we were able to uncover regulatory networks, mainly shaping DNA damage response and survival pathways. We, finally, developed a combinatorial miR-based overall survival score, further highlighting the pathobiological impact of AGO2 and miR-ome perturbations.
Item Type: | Thesis (PhD thesis) | ||||||||||
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URN: | urn:nbn:de:hbz:38-701723 | ||||||||||
Date: | 26 April 2023 | ||||||||||
Language: | English | ||||||||||
Faculty: | Faculty of Medicine | ||||||||||
Divisions: | Faculty of Medicine > Innere Medizin > Klinik I für Innere Medizin - Hämatologie und Onkologie | ||||||||||
Subjects: | Medical sciences Medicine | ||||||||||
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Date of oral exam: | 26 April 2023 | ||||||||||
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Refereed: | Yes | ||||||||||
URI: | http://kups.ub.uni-koeln.de/id/eprint/70172 |
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