The role of cystathionine y-lyase and hydrogen sulfide in glucose transporter Glut1 expression in macrophages

Thesis (M.S.) University of Alaska Fairbanks, 2023Hydrogen sulfide (H₂S) is an endogenous gasotransmitter that regulates immune function and energy metabolism in macrophages. While it is known to impair mitochondrial respiration at high levels, recent studies have shown that it promotes aerobic glycolysis, highlighting its potential role in regulating macrophage inflammatory response. The investigation of the link between H₂S and glucose metabolism in macrophages is of particular significance due to the role of glycolysis in driving macrophage innate immune functions. Inflammation stimulates macrophages to increase glycolysis by upregulating the expression of Glut1, the primary glucose transporter in these cells. Nuclear factor (NF)-κB is a transcription factor that elicits inflammation by regulating the expression of pro-inflammatory cytokines and chemokines in response to stimuli such as lipopolysaccharide (LPS), a bacterial toxin. However, NF-κB controls Glut1 expression in macrophages during immune responses. The phosphoinositide 3-kinase (PI3k)/ protein kinase B (Akt) signaling also plays a role in regulating NF-κB activity and glucose metabolism. The precise impact of H₂S on the PI3k/Akt and NF-κB signaling pathways, as well as Glut1 expression in macrophages, remains poorly understood. The goal of my thesis research is to test for a link between endogenously produced H₂S and Glut1 expression during the pro-nflammatory response in macrophages. Small interfering (si)RNAs were used to knockout cystathionine g-lyase (CSE) gene expression and block endogenous H₂S production in LPS-stimulated macrophages and the effect on LPS-induced Glut1 protein and mRNA expression was measured. Silencing CSE in LPS-stimulated macrophages reduced Glut1 mRNA levels suggesting that H₂S regulates Glut1 levels in inflammatory macrophages. Pre-treatment of macrophages with drug inhibitors targeting NF-κB or PI3k/Akt prevented LPS-induced Glut1 expression, implicating the signaling activity of these proteins as regulators of inflammation induced Glut1 expression. Silencing CSE decreased NF-κB activation in LPS-stimulated macrophages, suggesting that endogenous H₂S acts via NF-κB to supports Glut1 expression. To determine whether H₂S supports the LPS/NF-κB/Glut1 response, we treated LPS induced macrophages with GYY4137, a slow releasing H₂S-donor molecule. Low levels of exogenous H₂S did not change Glut1 expression in LPS treated cells. However, high levels of H₂S inhibited NF-κB activation and Glut1 expression and increased Akt activation, suggesting an antiinflammatory role of elevated H₂S levels. The anti-inflammatory effect of elevated levels of H₂S on LPS-induced NF-κB activation and Glut1 expression shows a marked difference from the pro-inflammatory impact of enzymatically produced levels, emphasizing the importance of distinguishing between the source and concentration of H₂S. These findings suggest that H₂S plays a role in inflammatory Glut1 expression through modulating NF-κB and Akt activity in macrophages.National Institute of Health Common Fund, awards TL4GM118992, RL5GM118990, & UL1GM118991Chapter 1. General introduction -- Chapter 2. Cystathionine γ-lyase and hydrogen sulfide modulates glucose transporter Glut1 expression via NF-κB and PI3k/Akt in macrophages during inflammation 1 -- Chapter 3. General conclusion -- Appendix: Cystathionine γ-lyase and hydrogen sulfide modulates glucose transporter Glut1 expression via NF-κB and PI3k/Akt in macrophages during inflammation

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Horizontal Symmetries for the Supersymmetric Flavor Problem

The heaviness of the third family fermions and the experimental absence of large flavor violating processes suggest, in supersymmetric theories, that the three families belong to a $2+1$ representation of a horizontal symmetry $G_H$. In this framework, we discuss a class of models based on the group U(2) that describe the fermion flavor structure and are compatible with an underlying GUT. We study the phenomenology of these models and focus on two interesting scenarios: In the first one, the first and second family scalars are assumed to be heavier than the weak scale allowing for complex soft supersymmetry breaking terms. In the second one, all the CP-violating phases are assumed to be small. Both scenarios present a rich phenomenology in agreement with constraints from flavor violating processes and electric dipole moments.Comment: 22 pages, LaTex. Minor changes. Version to appear in Nucl. Phys.

Implementation and engagement of the SMART Work & Life sitting reduction intervention: an exploratory analysis on intervention effectiveness

Background: To enhance the impact of interventions, it is important to understand how intervention engagement relates to study outcomes. We report on the level of implementation and engagement with the SMART Work & Life (SWAL) programme (delivered with (SWAL plus desk) and without a height-adjustable desk (SWAL)) and explore the effects of different levels of this on change in daily sitting time in comparison to the control group. Methods: The extent of intervention delivery by workplace champions and the extent of engagement by champions and participants (staff) with each intervention activity was assessed by training attendance logs, workplace champion withdrawal dates, intervention activities logs and questionnaires. These data were used to assess whether a cluster met defined criteria for low, medium, or high implementation and engagement or none of these. Mixed effects linear regression analyses tested whether change in sitting time varied by: (i) the number of intervention activities implemented and engaged with, and (ii) the percentage of implementation and engagement with all intervention strategies. Results: Workplace champions were recruited for all clusters, with 51/52 (98%) attending training. Overall, 12/27 (44.4%) SWAL and 9/25 (36.0%) SWAL plus desk clusters implemented all main intervention strategies. Across remaining clusters, the level of intervention implementation varied. Those in the SWAL (n = 8 (29.6%) clusters, 80 (32.1%) participants) and SWAL plus desk (n = 5 (20.0%) clusters, 41 (17.1%) participants) intervention groups who implemented and engaged with the most intervention strategies and had the highest percentage of cluster implementation and engagement with all intervention strategies sat for 30.9 (95% CI -53.9 to -7.9, p = 0.01) and 75.6 (95% CI -103.6 to -47.7, p < 0.001) fewer minutes/day respectively compared to the control group at 12 month follow up. These differences were larger than the complete case analysis. The differences in sitting time observed for the medium and low levels were similar to the complete case analysis. Conclusions: Most intervention strategies were delivered to some extent across the clusters although there was large variation. Superior effects for sitting reduction were seen for those intervention groups who implemented and engaged with the most intervention components and had the highest level of cluster implementation and engagement. Trial Registration: ISRCTN11618007. Registered on 24 January 2018. https://www.isrctn.com/ISRCTNISRCTN11618007

Differential gene expression in mouse primary hepatocytes exposed to the peroxisome proliferator-activated receptor α agonists

BACKGROUND: Fibrates are a unique hypolipidemic drugs that lower plasma triglyceride and cholesterol levels through their action as peroxisome proliferator-activated receptor alpha (PPARα) agonists. The activation of PPARα leads to a cascade of events that result in the pharmacological (hypolipidemic) and adverse (carcinogenic) effects in rodent liver. RESULTS: To understand the molecular mechanisms responsible for the pleiotropic effects of PPARα agonists, we treated mouse primary hepatocytes with three PPARα agonists (bezafibrate, fenofibrate, and WY-14,643) at multiple concentrations (0, 10, 30, and 100 μM) for 24 hours. When primary hepatocytes were exposed to these agents, transactivation of PPARα was elevated as measured by luciferase assay. Global gene expression profiles in response to PPARα agonists were obtained by microarray analysis. Among differentially expressed genes (DEGs), there were 4, 8, and 21 genes commonly regulated by bezafibrate, fenofibrate, and WY-14,643 treatments across 3 doses, respectively, in a dose-dependent manner. Treatments with 100 μM of bezafibrate, fenofibrate, and WY-14,643 resulted in 151, 149, and 145 genes altered, respectively. Among them, 121 genes were commonly regulated by at least two drugs. Many genes are involved in fatty acid metabolism including oxidative reaction. Some of the gene changes were associated with production of reactive oxygen species, cell proliferation of peroxisomes, and hepatic disorders. In addition, 11 genes related to the development of liver cancer were observed. CONCLUSION: Our results suggest that treatment of PPARα agonists results in the production of oxidative stress and increased peroxisome proliferation, thus providing a better understanding of mechanisms underlying PPARα agonist-induced hepatic disorders and hepatocarcinomas