👤 Chris Elias

Inhibition of amyloid precursor protein (APP) beta-site cleaving enzyme 1 (BACE1) has been a target for Alzheimer's disease (AD) therapeutic development. Here, we report our identification of APP-selective BACE1 (ASBI) inhibitors that are selective for APP as the substrate and BACE1 as the target enzyme. A known fluoro aminohydantoin (FAH) inhibitor compound was identified by screening a compound library for inhibition of BACE1 cleavage of a maltose binding protein (MBP)-conjugated-APPC125 substrate followed by optimization and IC50 determination using the P5-P5' activity assay. Optimization of the screening hit led to candidate FAH65, which displays selectivity for inhibition of APP cleavage with little activity against other BACE1 substrates neuregulin 1 (NRG1) or p-selectin glycoprotein ligand-1 (PSGL1). FAH65 shows little inhibitory activity against other aspartyl proteases cathepsin D (Cat D) and BACE2. FAH65 reduces BACE1 cleavage products soluble APPβ (sAPPβ) and the β C-terminal fragment (βCTF), as well as amyloid-β (Aβ) 1-40 and 1-42, both in vitro in cells and in vivo in an animal model of AD. In a murine model of AD, FAH65 improved the discrimination score in the Novel Object Recognition (NOR) memory testing paradigm. The active enantiomer of racemate FAH65, FAH65E(-), displays good brain-penetrance and target engagement, meriting further pre-clinical development as an ASBI that may reduce Aβ levels and overcome the deleterious effects of the non-selective BACE1 inhibitors that have failed in the clinic. FAH65E(-) has the potential to be a first-in-class oral therapy that could be used in conjunction with an approved anti-Aβ antibody therapy for AD. Show less

Plants need to integrate internal and environmental signals to mount adequate stress responses. The NUCLEAR PORE COMPLEX (NPC) component HIGH EXPRESSION OF OSMOTICALLY RESPONSIVE GENES 1 (HOS1) is emerging as such an integrator, affecting responses to cold, heat, light, and salinity. Stress conditions often converge in a low-energy signal that activates SUCROSE NON-FERMENTING 1-RELATED KINASE 1 (SnRK1) to promote stress tolerance and survival. Here, we explored the role of HOS1 in the SnRK1-dependent response to low-energy stress in Arabidopsis thaliana, using darkness as a treatment and a combination of genetic, biochemical, and phenotypic assays. We show that the induction of starvation genes and plant tolerance to prolonged darkness are defective in the hos1 mutant. HOS1 interacts physically with the SnRK1α1 catalytic subunit in yeast two-hybrid assays and in planta, and the nuclear accumulation of SnRK1α1 is reduced in the hos1 mutant. Likewise, another NPC mutant, nup160, exhibits lower activation of starvation genes and decreased tolerance to prolonged darkness. Importantly, defects in low-energy responses in the hos1 background are rescued by fusing SnRK1α1 to a potent nuclear localization signal or by sugar supplementation during the dark treatment. Altogether, this work demonstrates the importance of HOS1 for the nuclear accumulation of SnRK1α1, which is key for plant tolerance to low-energy conditions. Show less

In chronic Chagas disease, Trypanosoma cruzi-specific T-cell function decreases over time, and alterations in the homeostatic IL-7/IL-7R axis are evident, consistent with a process of immune exhaustion. IL-27 is an important immunoregulatory cytokine that shares T-cell signaling with IL-7 and other cytokines of the IL-12 family and might be involved in the transcriptional regulation of T-cell function. Here, we evaluated the expression and function of IL-27R in antigen-experienced T cells from subjects with chronic Chagas disease and assessed whether in vitro treatment with IL-27 and IL-7 might improve T. cruzi-specific polyfunctional T-cell responses. In vitro exposure of PBMCs to T. cruzi induced a downregulation of IL-27R in CD4+ T cells and an upregulation in CD8+ T cells in subjects without heart disease, while IL-27R expression remained unaltered in subjects with more severe clinical stages. The modulation of IL-27R was associated with functional signaling through STAT3 and STAT5 and induction of the downstream genes TBX21, EOMES and CXCL9 in response to IL-27. In vitro treatment of PBMCs with IL-27 and IL-7 improved monofunctional and polyfunctional Th1 responses, accompanied by the induction of IL-10 and Bcl-2 expression in subjects without heart disease but did not improve those in subjects with cardiomyopathy. Our findings support the process of desensitization of the IL-27/IL-27R pathway along with disease severity and that the pro-inflammatory and immunomodulatory mechanisms of IL-27 might be interconnected. Show less