VictorJuiz/thesis huggingface dataset:
Endocrine Regulation of Stem Cells and the Niche in Adult Mammopoiesis

Adult mammopoiesis occurs in close synchronization with reproductive development when the hypothalamic-pituitary-ovarian axis delivers integral systemic hormone cues to propel mammary morphogenesis during puberty, remodeling during reproductive cycles and functional differentiation following pregnancy. While hormones remain the driving force behind normal glandular development, increased life-time hormone exposure is a strong risk factor for breast cancer. Breast cancer heterogeneity has been attributed to different cells of origin and/or different mutation repertoires. Stem/progenitor cells are intensely investigated as cells of origin given their regenerative and self-renewal properties that provide conceivable advantage in cancer. Although hormones have a fundamental influence in breast cancer, their capacity to regulate stem/progenitor cells was unknown, and presents the central directive in this thesis. Employing mouse models, we show that mammary epithelial subpopulations and in particular, stem cells, are highly responsive to ovarian hormones and depend on key molecular events. A progesterone peak during the luteal phase of reproductive cycles results in a significant increase in stem cell-enriched basal cells and an expansion of stem cells measured by in vivo transplantation assays, with rapid development of lobuloalveoli. Progesterone was found to stimulate expression of mitogenic ligands, RANKL and Wnt4, in ER+PR+ luminal epithelial niche cells concomitant with increased expression of their receptors and target genes in the ER-PR- basal stem cell population, suggesting a cross-talk between luminal and basal cells that elicits stem cell expansion within the niche. The requirement of RANKL signaling for hormone-induced mammary stem cell dynamics was further explored utilizing mice deficient for its receptor, RANK, and by pharmacological inhibition of RANKL. Disruption of RANKL/RANK signaling resulted in abrogated activation of the basal stem cell-enriched population and alveolar progenitor cells in response to progesterone. This was accompanied by a marked reduction in cell proliferation, cell cycle regulators, alveolar lineage determinants and notably, in epithelial Wnt responsiveness. Thus, progesterone orchestrates a series of molecular events in the mammary stem cell niche where RANK is effectively positioned to deliver instructive signals to stem cells, culminating in stem cell recruitment and alveolar regeneration, processes which when deregulated have considerable potential to promote breast cancer pathogenesis.

Keywords: stem cells
mammary gland
hormones
Advisor: Khokha, Rama
Comparative Interactome Investigation of γ-secretase Complex in Alzheimer’s Disease

γ-Secretase plays a pivotal role in the production of neurotoxic amyloid β-peptide (Aβ), the principal component of amyloid plaques present in Alzheimer’s disease. It consists of a core complex of presenilin (PS), nicastrin, anterior pharynx-defective 1 (Aph-1), and presenilin enhancer 2 (Pen-2) proteins. PS harbors the catalytic aspartates required for regulated intramembrane proteolysis and the paralogs (PS1 and PS2) contribute to the assembly of distinct subpopulations of γ-secretases that may fulfill distinct roles. To characterize the molecular environments of distinct γ-secretases complexes in-depth quantitative comparisons were performed on 1) wild-type PS1 and its derivative carrying point mutations known to cause heritable early-onset AD in mice, and 2) PS1- or PS2-containing γ-secretase complexes equipped with N-terminal tandem-affinity purification (TAP) tags on PS paralogs in HEK293 cells. Isobaric labeling of co-purifying peptides for quantitative mass spectrometry revealed that γ-secretase complexes interact with other protein networks, including the cellular catenin-cadherin network, the molecular machinery that targets and fuses synaptic vesicles to cellular membranes, and the H+-transporting lysosomal ATPase macro-complex. The study revealed mature γ-secretase complexes containing PS1 or mutant PS1 to be indistinguishable in their protein composition, confirmed several previously proposed γ-secretase interactors, identified many novel interactors and uncovered a subset of proteins which can engage in robust interactions with γ-secretase complexes in individual cell types but may escape detection when whole brains are used as biological source materials. Interestingly, signal peptide peptidase (SPP), a Type II TM cleaving aspartyl protease, was pre-dominantly found to co-purify with PS2-containing γ-secretase complexes and could be shown not to influence their maturation but to affect cleavage or release of cellular Aβ. A model emerged from this work that suggests PS1 and PS2 paralogs may divide up the task of handling a broad range of membrane stubs at least in part by associating with different molecular environments.

Keywords: Alzheimer's Disease
Gamma-secretase
Amyloid beta peptide
Proteomics
Advisor: Schmitt-Ulms, Gerold
Thucydides on the Outbreak of War

This project illuminates Thucydides’ political thought through a novel interpretation of the first book of the History of the Peloponnesian War. It explores how Thucydides reveals the human causes of war through the outbreak of a particular war, the Peloponnesian war. The primary claim is that Thucydides intends the breakdown of the Thirty Years’ Peace between Athens and the Peloponnesians, which inaugurates the great Peloponnesian war, to be understood by grasping how the characters of the Athenian and Spartan regimes contribute to the outbreak of the war and, crucially, how Athens and Sparta differently express human nature. In broad outline, the History’s first book reveals how the regime characters of Athens and Sparta inform their respective foreign policies, but also how the interaction between the two cities—informed by the distinctive necessities pressing upon them—causes the Hellenic status quo to tremble and fall. Throughout the first book, while never obscuring the specific events triggering war, Thucydides progressively develops and expands his original statement that it was Spartan fear of Athenian power that compelled the fighting. The study argues that necessity (or compulsion) is the bright thread that Thucydides uses to guide his reader through the episodes of the first book, from the immediate causes of the Peloponnesian war to the human causes of war, from the particular events to the History’s universal themes.

Keywords: Thucydides
War
Advisor: Orwin, Clifford
Constitutional Possibilities: An Inquiry Concerning Constitutionalism in British Columbia

Constitutional change is relentless. Today, states jockey with regional associations, international organizations, transnational networks and sub-state authorities to define the scope of legitimate political conduct and establish rival bases for political affiliation. Constitutional theorists must be resolute but they should not be rigid. Especially in such uncertain conditions, theories are best understood not as plans to be implemented but as hypotheses to be tested. Charles Sabel and David Dyzenhaus write separately but share this pragmatic orientation, in which doubt is indispensable and truth is the end of public inquiry. They also share a distinctive belief that constitutionalism serves a moral end: it is the project of cultivating citizens who conceive their political community in terms of the commitments revealed by its practices. Their position, which is well suited for contemporary challenges, warrants elaboration and examination. British Columbia offers an ideal constitutional laboratory for that test. During the 1970s and 1980s, doubts mounted about the legitimacy of the constitutional settlement imposed by the Crown in the westernmost province of Canada. Legal, political and constitutional decisions raised the possibility that aboriginal rights and title survived colonization and Confederation. Since 1990, their existence has been confirmed in a cascade of constitutional experiments. Those initiatives can be distilled into four procedures: litigation, negotiation, consultation and collaboration. Although they have delivered practical benefits to some indigenous peoples, these procedures have not transformed provincial politics into a moral endeavour. The constraints on constitutionalism in British Columbia are both conceptual and institutional. Despite marginal improvements, those constraints endure and constitutionalism remains for now the sporadic pursuit of a small elite. To conceive constitutionalism as a project is to set a sound but exacting standard. Although British Columbia falls short, its failure is informative: the theory is useful.

Keywords: constitutionalism
constitutional law
constitutional theory
Aboriginal rights
experimentation
Advisor: Choudhry, Sujit
Macroinvertebrate Community Structure and Function in Seasonal, Low-land, Tropical Streams across a Pristine-rural-Urban Land-use Gradient

Tropical freshwater ecosystems are understudied and not well understood relative to temperate systems; however, they are becoming increasingly imperiled by escalating anthropogenic impacts. The aim of this thesis was to investigate how tropical freshwater macroinvertebrate communities changed both structurally and functionally over a pristine-rural-urban land-use gradient, in relation to different spatial and temporal scales, as well as to the availability of potential food sources. Fifteen streams in the Panama Canal Watershed were sampled during the dry and wet seasons of 2007 and 2008, for macroinvertebrate communities (benthic and leaf litter), environmental variables, and potential food sources. Along the land-use gradient, in both habitat types, taxon richness, diversity, and evenness all decreased significantly; whereas, abundance increased significantly. For the benthic macroinvertebrate community, unique variation was explained equally well by local (water chemistry and sediment type) and landscape (riparian vegetation and watershed land use) characteristics in the dry season, and landscape characteristics explained slightly more variation in the wet season. Leaf-litter macroinvertebrate community unique variation was better explained by local variables than by landscape variables in both seasons. In terms of potential food resources, fine detritus and inorganic material were the most common across all streams (increased quantities in urban streams) and seasons; whereas, the availability of diatoms and leaf material increased in the dry season. Using gut content analyses, we found that collectors (gatherers and filterers) were by far the most common functional feeding group, increasing in abundance along the land-use gradient. Predators, shredders, and scrapers were all most abundant in pristine streams and decreased along the land-use gradient. Finally, using seven community metrices, a potential biomonitoring tool was developed, the Neotropical Low-land Stream Multimetric Index (NLSMI), which distinguished well among the different levels of stream impairment. This study demonstrated that tropical communities were negatively affected by human land alteration, but that community responses depended on the habitat sampled, the influence of different spatial scales varied between the seasons, and the effect of food resources appeared to be complex. These aspects must be taken into consideration for management decisions and restoration strategies to be effective.

Keywords: Freshwater
Tropical stream
Macroinvertebrates
Human impacts
Advisor: Williams, D. Dudley
Minding the Gap: Understanding the Experiences of Racialized/Minoritized Bodies in Special Education

The issue of special education in the United States has been a contentious issue, at best, for the past 40 years. In Ontario, to a lesser extent, there have been issues of equal access to education for minoritized and racialized students. Special education in the Toronto area has not been without its issues surrounding parental advocacy, the use of assessments, and disproportionate number of English Language Learners in special education. This project examines how racialized and minoritized families understand special education practices and policies, specifically within the Toronto, York, Peel, and Halton Regions. The investigation is informed by nine interviews with students in grades 7 to 12, their respective mothers, and five special education administrators and educators. Students and parents identified themselves as Black, Latino/a, and South Asian. Within these categories, parents identified themselves as Somali, Trinidadian, Jamaican, and Punjabi-Sikh. Students were identified with a range of disabilities including learning, behavioural, and/or intellectual. This research focuses on ways to interrogate and examine the experiences of minoritized students and their parents by bringing forward otherwise silenced voices and understanding what it means to “speak out” against the process of identification and placement in special education. The findings of this investigation suggest a disconnect how policies and practices are implemented, and how, parents’ rights are understood. In particular, policies are inconsistently applied and are subject to the interpretation of educators and administrators, especially in relation to parental involvement and how much information should be released to families. The issue of language acquisition being read as a disability was also a noted concern. This investigation points to implications for teacher education programs, gaps in parental advocacy and notions of parental participation within schools, and re-examining special education assessments, practices, and policies.

Keywords: special education
minorities
learning disabilities
anti-racist discursive framework
critical race theory
Advisor: Dei, George Jerry Sefa
Requirements for Notch Signaling in Positive Selection and Effector Function of CD8 T Cells

The generation of the cytotoxic CD8 T cell response is dependent on the functional outcomes imposed by the intrathymic constraints of differentiation and self-tolerance. Although thymic function can be partly replicated in vitro using OP9-DL1 cell cultures to yield CD8 αβ T cell receptor (TCR)-bearing cells from hematopoietic progenitor cells, a comprehensive and functional assessment of entirely in-vitro generated CD8 T cells derived from bone marrow hematopoietic stem cells (BM-HSCs) has not been established and remains controversial. Here we demonstrate that a phenotypic, molecular, and functional signature of in vitro-derived CD8 T cells is akin to that of ex vivo CD8 T cells. Transfer of in vitro-derived CD8 T cells into syngeneic and immunodeficient host mice showed no graft-versus-host response, while a robust homeostatic proliferation was observed, respectively. These findings, along with a diverse and broad TCR repertoire expressed by the in vitro-derived CD8 T cells, allowed for the successful generation of antigen (Ag)-specific T cells to be obtained from an entirely in vitro-generated CD8 T cell pool, which calls for further tailoring of their use against viral infections or malignancies. Furthermore, I demonstrate that Notch signaling regulates the expression of the cytolytic molecule Granzyme A in CD8+ T cells. This is supported by the inability of Notch-deprived TCR-signaled CD8 T cells to express Granzyme A, while CD8 T cells that received Notch signals readily expressed Granzyme A, suggesting that Notch signaling is a prerequisite for induction of this cytolytic molecule. We further demonstrate that Notch signaling by OP9 cells allows for efficient differentiation of conventional effector CD8 T cells from SAP-/- BM-derived HSCs and restricts differentiation of innate CD8 T cells while allowing for differentiation of IL17-producing CD8 T cells from BM-HSCs isolated from Itk-/-Rlk-/- (DKO) mice. Moreover, we reveal that the process of positive and negative selection in vitro is constrained by peptide-MHC (pMHC) class I expressed by the OP9 cells and disclose that the commitment of DP precursors to the CD8 T cell lineage is facilitated by Notch signaling. Our findings further establish the requirement for Notch receptor-ligand interactions throughout intrathymic T cell differentiation.

Keywords: CD8 T cells
Notch signaling
thymus
OP9 cells
Advisor: Zuniga-Pflucker, Juan Carlos
Deep Brain Stimulation of the Subthalamic and Entopeduncular Nuclei in an Animal Model of Tardive Dyskinesia

Deep brain stimulation (DBS) has emerged as a potential intervention for treatment-resistant tardive dyskinesia (TD). Despite promising case reports, no consensus exists regarding optimal stimulation parameters, neuroanatomical target for DBS in TD, or mechanisms underlying its anti-dyskinetic effects. We used vacuous chewing movements (VCMs) in rats treated chronically with haloperidol (HAL) as a TD model to address some of these issues. We show that acute DBS applied to the subthalamic nucleus (STN) or the entopeduncular nucleus (EPN) suppresses VCMs without affecting locomotor activity. Using immediate early gene mapping with zif268 as an index of neuronal activity, we found that STN-DBS induced decreases in activity throughout the basal ganglia, whereas EPN-DBS increased activity in projection regions. While chemical inactivation of the STN or EPN with the GABAA agonist muscimol also suppressed VCMs, muscimol infusion did not mimic the changes in neuronal activity induced by DBS, suggesting that DBS is not equivalent to functional inactivation. We next examined the contribution of serotonin (5-HT) and dopamine (DA) to the anti-dyskinetic effects of DBS. Decreasing 5-HT transmission pharmacologically or with serotonergic lesions decreased VCMs. Using microdialysis and zif268 mapping, we determined that STN- but not EPN-DBS decreased 5-HT release and activity of raphe neurons. However, when the decrease in 5-HT induced by STN-DBS was prevented by pre-treating rats with fluoxetine or fenfluramine, we found that decreasing 5-HT is not necessary for the anti-dyskinetic effects of DBS. STN-DBS transiently increased striatal DA release in intact rats only, whereas EPN-DBS had no effect on DA release. Moreover, pharmacologically elevating DA levels did not suppress VCMs. Together these findings lead us to conclude that increased DA release does not contribute to the anti-dyskinetic effects of DBS. Finally, we compared depressive- and anxiety-like behaviours induced by chronic DBS of the EPN and STN, since adverse psychiatric effects of DBS have become a significant clinical concern. STN-DBS but not EPN-DBS induced depressive-like behaviour in a learned helplessness task. We established that the chronic HAL VCM model preparation may be used to explore mechanisms underlying anti-dyskinetic and psychiatric effects of DBS, and provided the first investigations into these mechanisms.

Keywords: deep brain stimulation
subthalamic
entopeduncular
tardive dyskinesia
haloperidol
serotonin
dopamine
Advisor: Nobrega, José
Aesthetics of Social Work: Governing Risky Spaces and Youth Subjects through Techniques of Visuality

In the wake of a rescaling of national state welfare responsibilities, urban centres, like the city of Toronto, have become new governance sightlines for managing the deleterious effects of a globalised restructuring of capitalist economies. Toronto is now trafficking its multicultural and “creative city” flare in regional and global markets to secure capital investment necessary to float its newly acquired fiscal responsibilities, including welfare and social services provisioning. And a host of local private-public partnerships have appeared as “shadow state” actors to assist in the suturing of disenfranchised communities to the operative logics of neo-liberal governance and globalised city aspirations. Social welfare and urban studies literature has not been attentive to the increasing reliance on visuality and the “aesthetic” more broadly in securing these desired social and economic outcomes. My ethnographically based dissertation picks up this analytical slack by inciting a two-fold intervention: First, I hone in on the efficacious properties of visual images produced within 3 different social policy spaces and their presumed roles in constituting the domains of social interaction and production. This analysis illustrates that different policy crafting experts understand the “aesthetic” as a remunerative technology of governance - for regulating the problematics of socio-economic and racialised difference, and for mediating rifts in the social fabric as fallout from welfare retrenchment. Second, I examine the ways in which certain normativised aesthetic sensibilities connected to neoliberal urbanism serve as both a calculative resource for re-defining certain spaces and subjects as problematic and thus controllable, and an interpellative mechanism for assembling moralized subjects around the dictates of responsibility and (self) empowerment. The dissertation argues that although these aesthetic governance strategies are resulting in a depoliticisation of communities, and a moralised segregation of compliant and non-compliant subjects played out along racialised /economic lines, there exists a level of disruption transpiring in the spaces of policy implementation. In situ attention to these disruptions, layered with a reflexive analytical restaging of these events and a critical analysis of deployed governance strategies are proposed as a grounding for social work, research and social policy praxis.

Keywords: youth policy
social welfare
Advisor: Williams, Charmaine