HPK1-mediated negative regulation of T-cell activation

Die Interaktion zwischen (SRC homology 2 (SH2)-domain-containing leukocyte protein of 76 kDa) SLP76 und (Hematopoietic progenitor kinase1) HPK1 ist essentiell für eine erst kürzlich entdeckte Negativ-Regulation der T-Zell-Aktivierung. Es wurde gezeigt, dass eine einzige Punktmutation in SLP76 (S376A), die Phosphorylierung dieses Proteins durch HPK1 verhindert und somit die Negativ-Regulation beeinträchtigt. Folglich, sind reagieren T-Zellen dieser Mutante senitiver auf aktivierende Stimuli. SLP76 ist eine Hauptkomponente einer sich, bei T-Zell Rezeptor Stimulation, bildenden Signaling-Plattform. Zahlreiche Prozesse können von SLP76-mediiertem Signaling beeinflusst werden wie z.B.: Zell-Proliferation, -Survival, -Maturation und Differenzierung. SLP76 ist darüber hinaus bekanntlich essentiell für T-Zell Entwicklung. Ein SLP76-S376A Mausmodell wurde generiert um die physiologische Relevanz dieser defekten Negativ-Regulierung zu überprüfen. Diese Arbeit ist eine Charakterisierung eines SLP76-S376A mutanten Mousmodells, mit Fokus auf frühe Signaling-Events, Downstream-Effektorfunktionen und auch T-Zell Entwicklung im Thymus. In Übereinstimmung mit publizierten Daten für das HPK1 knock-out Mausmodell, demonstriert die SLP76-S376A Mutante keinerlei Defekte in T-Zell Entwicklung. Die SLP76-S376A Mutante zeigt jedoch, erhöhte Proliferationsraten und ERK (Extracellular signal-regulated kinase) Phosphorylierung in CD4+ und CD8+ SLP76-S376A T-Zellen, so wie auch inkrementierte INF-γ Produktion in SLP76-S376A CD8+ T-Zellen, im Vergleich zu Wildtyp T-Zellen. Schlussendlich präsentiert die SLP76-S376A Mutante einen Satz veränderter T-Zell-Eigenschaften welche von einer defekten Negativ-Regulierung, der T-Zell Rezeptor Aktivierung, stammen. In einem HPK1 knock-out Mausmodell wurde erst kürzlich verstärkte, T-Zell abhängige, Anti-Tumorimmunaktivität demonstriert (Alzabin et al. 2010). Aus diesem Grund habe ich eine bioluminiszente Tumorzelllinie entworfen, welche verwendet werden kann um die Rolle der HPK1-SLP76-Interaktion in Anti-Tumorimmunaktivität zu eruieren.A novel negative regulatory pathway of T-cell activation has been recently described, involving the scaffold protein SRC homology 2 (SH2)-domain-containing leukocyte protein of 76 kDa (SLP76) and the Hematopoietic progenitor kinase 1 (HPK1). It was shown that a single point mutation on SLP76 (S376A) prevents phosphorylation of this protein by HPK1 and impairs the negative regulation of T-cell activation, thus rendering T-cells more sensitive to activating stimuli. SLP76 is a major component of a signaling platform assembled upon antigen recognition by T-cells. Hence, SLP76 influences various processes including: T-cell survival, proliferation, maturation and differentiation. Furthermore, SLP76 has been reported to be essential for T-cell development. A SLP76-S376A mutant mouse model has been generated to investigate the physiological consequences of impairing the negative regulatory pathway mentioned above. One of the aims of this Master Thesis was to characterize these SLP76-S376A mutant mice, focusing in particular on the effects of the mutation on early TCR-mediated signaling and downstream effector functions of mature T-cells, as well as on thymic T-cell development, Our results indicate that SLP76-S376A mice do not exhibit significant defects in T-cell development, in line with previous reports with HPK1 knock-out mice. However, we demonstrated that TCR-stimulation induced higher Extracellular signal-regulated kinases (ERKs) phosphorylation in SLP76-S376A peripheral T-cells compared to wild type cells. Moreover, we observed higher proliferation rates for SLP76-S376A mutant CD4+ and CD8+ T-cells, as well as increased INF-γ production for SLP76-S376A mutant CD8+ T-cells. Collectively, these data suggest that SLP76-S376A mice display a set of altered T-cell properties most likely dependent on a defective negative regulation of TCR-induced signaling. Recent data demonstrating increased T-cell-dependent anti-tumor immunity in HPK1 knock-out mice (Alzabin et al., 2010), suggest that SLP76-S376A mice may be an optimal tool for investigating whether the negative regulatory function of HPK1 is responsible for its ability to control anti-tumor T-cell responses . Therefore, I also developed and validated a bioluminescent cancer cell line that will be useful to address the importance of the HPK1-SLP76 pathway in anti-tumor immunity

Health inequity in workers of Latin America and the Caribbean

Latin America and the Caribbean (LAC) is the world’s most inequitable region in terms of wealth distribution. The full scale of social inequalities in health has been hidden by the lack of reliable data. This study aimed to measure and compare health inequalities in the working population within and between 15 countries of LAC

Inactive X chromosome-specific reduction in placental DNA methylation

Genome-wide levels of DNA methylation vary between tissues, and compared with other tissues, the placenta has been reported to demonstrate a global decrease in methylation as well as decreased methylation of X-linked promoters. Methylation is one of many features that differentiate the active and inactive X, and it is well established that CpG island promoters on the inactive X are hypermethylated. We now report a detailed analysis of methylation at different regions across the X in male and female placenta and blood. A significant (P < 0.001) placental hypomethylation of LINE1 elements was observed in both males and females. Relative to blood placental promoter hypomethylation was only observed for X-linked, not autosomal promoters, and was significant for females (P < 0.0001) not males (P = 0.9266). In blood, X-linked CpG island promoters were shown to have moderate female methylation (66% across 70 assays) and low (23%) methylation in males. A similar methylation pattern in blood was observed for ∼20% of non-island promoters as well as 50% of the intergenic or intragenic CpG islands, the latter is likely due to the presence of unannotated promoters. Both intragenic and intergenic regions showed similarly high methylation levels in male and female blood (68 and 66%) while placental methylation of these regions was lower, particularly in females. Thus placental hypomethylation relative to blood is observed globally at repetitive elements as well as across the X. The decrease in X-linked placental methylation is consistently greater in females than males and implicates an inactive X specific loss of methylation in the placenta

Local Energy Markets in Action: Smart Integration of National Markets, Distributed Energy Resources and Incentivisation to Promote Citizen Participation

Since the Paris Agreement in 2016, the goals of limiting climate change and moving toward climate resilience stand. With a share of about 80% of global CO2 emissions, the energy sector is an essential driver for these goals. A shift to low-carbon energy production and a decentralized system for more efficient energy transmission distribution is necessary. In this paper, we present our work on Modelling of Power Exchanges, Algorithms for Local Energy Market (LEM), Competitiveness of Combined Heat and Power Plant (CHP) and Energy Feedback Devices. The study was conducted considering technical, economic, social and regulatory framework. For easy integration into energy simulations or a district energy management system (DEMS), a model for power exchanges was created that allows flexible input or deterministic price patterns. The algorithm handles the clearing of an LEM by a district aggregator using limit orders with the goal of increasing the share of locally consumed electricity using economic incentives. An investigation was conducted into the operation of flexible CHPs in low-carbon power systems to balance the volatility of renewable energy. An Energy Signal Light (ESL) was developed as an energy feedback device, which is integrated into the DEMS in a living lab and allows individual configuration. In summary, the results presented should be compared with those of other research approaches in the future and require qualitative and quantitative evaluation