Small molecule amyloid-beta protein precursor processing modulators lower amyloid-beta peptide levels via cKit signaling

Alzheimer’s disease (AD) is characterized by the accumulation of neurotoxic amyloid-β (Aβ) peptides consisting of 39-43 amino acids, proteolytically derived fragments of the amyloid-β protein precursor (AβPP), and the accumulation of the hyperphosphorylated microtubule-associated protein tau. Inhibiting Aβ production may reduce neurodegeneration and cognitive dysfunction associated with AD. We have previously used an AβPP-firefly luciferase enzyme complementation assay to conduct a high throughput screen of a compound library for inhibitors of AβPP dimerization, and identified a compound that reduces Aβ levels. In the present study, we have identified an analog, compound Y10, which also reduced Aβ. Initial kinase profiling assays identified the receptor tyrosine kinase cKit as a putative Y10 target. To elucidate the precise mechanism involved, AβPP phosphorylation was examined by IP-western blotting. We found that Y10 inhibits cKit phosphorylation and increases AβPP phosphorylation mainly on tyrosine residue Y743, according to AβPP751 numbering. A known cKit inhibitor and siRNA specific to cKit were also found to increase AβPP phosphorylation and lower Aβ levels. We also investigated a cKit downstream signaling molecule, the Shp2 phosphatase, and found that known Shp2 inhibitors and siRNA specific to Shp2 also increase AβPP phosphorylation, suggesting that the cKit signaling pathway is also involved in AβPP phosphorylation and Aβ production. We further found that inhibitors of both cKit and Shp2 enhance AβPP surface localization. Thus, regulation of AβPP phosphorylation by small molecules should be considered as a novel therapeutic intervention for AD.This work was supported by grants from the Alzheimer's Association, the Cure Alzheimer's Fund and the Boston University Alzheimer's Disease Center. Work at the BU-CMD is supported by R24-GM111625. (Alzheimer's Association; Cure Alzheimer's Fund; R24-GM111625 - Boston University Alzheimer's Disease Center)Accepted manuscrip

An oxindole efflux inhibitor potentiates azoles and impairs virulence in the fungal pathogen Candida auris

Candida auris is an emerging fungal pathogen that exhibits resistance to multiple drugs, including the most commonly prescribed antifungal, fluconazole. Here, we use a combinatorial screening approach to identify a bis-benzodioxolylindolinone (azoffluxin) that synergizes with fluconazole against C. auris. Azoffluxin enhances fluconazole activity through the inhibition of efflux pump Cdr1, thus increasing intracellular fluconazole levels. This activity is conserved across most C. auris clades, with the exception of clade III. Azoffluxin also inhibits efflux in highly azole-resistant strains of Candida albicans, another human fungal pathogen, increasing their susceptibility to fluconazole. Furthermore, azoffluxin enhances fluconazole activity in mice infected with C. auris, reducing fungal burden. Our findings suggest that pharmacologically targeting Cdr1 in combination with azoles may be an effective strategy to control infection caused by azole-resistant isolates of C. auris.U01 TR002625 - NCATS NIH HHS; MOP-133636 - CIHR; U19 AI110818 - NIAID NIH HHS; R35 GM118173 - NIGMS NIH HHS; FDN-154288 - CIHR; R01 AI141202 - NIAID NIH HHS; R01 AI073289 - NIAID NIH HHSPublished versio

Synthesis of Natural and Unnatural Sulfatide Ligands for NKT Cell Activation and Olefin Cross-metathesis of α-Methylene-β-lactones as a Methodology for the Rapid Assembly of β-Lactones

Sulfatides are innate glycosphingolipids shown to activate a subpopulation of type II NKT cells. Their activation has been reported to sometimes have antagonistic roles to those of type I NKT cells in some disease models. This has sparked a lot of interest in the synthesis of natural and unnatural sulfatides for an examination of their influence on NKT cell responses. The design, synthesis and evaluation of type II NKT cell activation of several sulfatide ligands are described in this thesis. A two-step methodology has been developed for the rapid assembly of disubstituted β-lactones. The first step is olefin cross metathesis (CM) of a-methylene-β-lactones with various alkene cross partners to furnish a-alkylidine-β-lactones. These are subsequently diastereoselectively reduced. A diverse library of β-lactones, including (±)-nocardiolactone has been prepared. Combining this approach with competitive activity-based protein profiling (ABPP) identified lead β-lactone inhibitors for several serine hydrolases, including disease-associated enzymes and enzymes of uncharacterized function

The Reaction of Grignard Reagents with Bunte Salts: A Thiol-Free Synthesis of Sulfides

S-Alkyl, S-aryl, and S-vinyl thiosulfate sodium salts (Bunte salts) react with Grignard reagents to give sulfides in good yields. The S-alkyl Bunte salts are prepared from odorless sodium thiosulfate by an S_N2 reaction with alkyl halides. A Cu-catalyzed coupling of sodium thiosulfate with aryl and vinyl halides was developed to access S-aryl and S-vinyl Bunte salts. The reaction is amenable to a broad structural array of Bunte salts and Grignard reagents. Importantly, this route to sulfides avoids the use of malodorous thiol starting materials or byproducts

Carbamoyl Anion Addition to Nitrones

The addition of carbamoyl anions derived from <i>N</i>,<i>N</i>-disubstituted formamides and LDA to <i>N</i>-<i>tert</i>-butyl nitrones is described. The reaction was demonstrated with a variety of formamides and nitrones and provided a direct route to α-(<i>N</i>-hydroxy)­amino amides. The use of a <i>tert</i>-leucinol derived chiral auxiliary on the nitrone provided products in good diastereoselectivity. Derivatization of the products by <i>tert</i>-butyl deprotection or <i>N</i>-deoxygenation was demonstrated

Immunomodulatory sphingosine-1-phosphates as plasma biomarkers of Alzheimer's disease and vascular cognitive impairment

10.1186/s13195-020-00694-3ALZHEIMERS RESEARCH & THERAPY12

An oxindole efflux inhibitor potentiates azoles and impairs virulence in the fungal pathogen Candida auris.

Candida auris is an emerging fungal pathogen that exhibits resistance to multiple drugs, including the most commonly prescribed antifungal, fluconazole. Here, we use a combinatorial screening approach to identify a bis-benzodioxolylindolinone (azoffluxin) that synergizes with fluconazole against C. auris. Azoffluxin enhances fluconazole activity through the inhibition of efflux pump Cdr1, thus increasing intracellular fluconazole levels. This activity is conserved across most C. auris clades, with the exception of clade III. Azoffluxin also inhibits efflux in highly azole-resistant strains of Candida albicans, another human fungal pathogen, increasing their susceptibility to fluconazole. Furthermore, azoffluxin enhances fluconazole activity in mice infected with C. auris, reducing fungal burden. Our findings suggest that pharmacologically targeting Cdr1 in combination with azoles may be an effective strategy to control infection caused by azole-resistant isolates of C. auris