The blood-brain barrier (BBB) poses a significant obstacle in developing therapeutics for neurodegenerative diseases and central nervous system (CNS) disorders. P-glycoprotein (P-gp), a multidrug resistance protein, is a critical gatekeeper in the BBB and plays a role in cancer chemoresistance. This paper uses cryo-EM P-gp structures as starting points with an induced fit docking (IFD) model to evaluate 19 pairs of compounds with known P-gp efflux data. The study reveals significant differences in binding energy and sheds light on structural modifications impact on efflux properties. In the cases examined, fluorine incorporation influences the efflux by altering the molecular conformation rather than proximal heteroatom basicity. Although there are limitations in addressing covalent interactions or when binding extends into the more flexible vestibule region of the protein, the results provide valuable insights and potential strategies to overcome P-gp efflux, contributing to the advancement of drug development for both CNS disorders and cancer therapies.

Prions were initially discovered in studies of scrapie, a transmissible neurodegenerative disease (ND) of sheep and goats thought to be caused by slow viruses. Once scrapie was transmitted to rodents, it was discovered that the scrapie pathogen resisted inactivation by procedures that modify nucleic acids. Eventually, this novel pathogen proved to be a protein of 209 amino acids, which is encoded by a chromosomal gene. After the absence of a nucleic acid within the scrapie agent was established, the mechanism of infectivity posed a conundrum and eliminated a hypothetical virus. Subsequently, the infectious scrapie prion protein (PrPSc) enriched for β-sheet was found to be generated from the cellular prion protein (PrPC) that is predominantly α-helical. The post-translational process that features in nascent prion formation involves a templated conformational change in PrPC that results in an infectious copy of PrPSc. Thus, prions are proteins that adopt alternative conformations, which are self-propagating and found in organisms ranging from yeast to humans. Prions have been found in both Alzheimer's (AD) and Parkinson's (PD) diseases. Mutations in APP and α-synuclein genes have been shown to cause familial AD and PD. Recently, AD was found to be a double prion disorder: both Aβ and tau prions feature in this ND. Increasing evidence argues for α-synuclein prions as the cause of PD, multiple system atrophy, and Lewy body dementia.

The addition of electron deficient radicals to the C2 position of indoles has been described in the literature as opposed to electrophilic addition at the C3 position. Density functional theory calculations were used to understand the switch in regioselectivity from C3 to C2 for indole to undergo radical additions. Electron deficient radicals have a lower barrier for reaction at C2 and a lower energy radical intermediate that benefits from benzylic radical stabilization. Trifluoromethyl radical addition has a lower energy barrier than acetonitrile radical, and the C3 addition transition state is just 0.8 kcal/mol higher than C2. This is supported by experimental observations.

In the literature, C-N coupling methods for the reaction of iodo-oxazole with 2-pyridinone were found to be low yielding. C-N coupling using silver benzoate additives with CuI catalysts and 4,7-dimethoxy-1,10-phenanthroline ligands has been developed to afford synthetically useful yields of the desired heterobicycle product. The reaction conditions are applied to the coupling of a range of iodo-heterocycles with 2-pyridinone. The coupling of a variety of NH-containing heterocycles with 4-iodo-oxazole is also demonstrated. The use of 2-, 4-, or 5-iodo-oxazole allows for the coupling of pyridinone to each oxazole position.

The direct cyanomethylation of indoles at the 2- or 3-position was achieved via photoredox catalysis. The versatile nitrile synthon is introduced as a radical generated from bromoacetonitrile, a photocatalyst, and blue LED as a light source. The mechanism of the reaction is explored by determination of the Stern-Volmer quenching constants. By combining photophysical data and mass spectrometry to follow the catalyst decomposition, the catalyst ligands were tuned to enable synthetically useful yields of radical coupling products. A range of indole substrates with alkyl, aryl, halogen, ester, and ether functional groups participate in the reaction, affording products in 16-90% yields. The reaction allows the rapid construction of synthetically useful cyanomethylindoles, products that otherwise require several synthetic steps.

The α-synuclein protein can adopt several different conformations that cause neurodegeneration. Different α-synuclein conformers cause at least three distinct α-synucleinopathies: multiple system atrophy (MSA), dementia with Lewy bodies (DLB), and Parkinson's disease (PD). In earlier studies, we transmitted MSA to transgenic (Tg) mice and cultured HEK cells both expressing mutant α-synuclein (A53T) but not to cells expressing α-synuclein (E46K). Now, we report that DLB is caused by a strain of α-synuclein prions that is distinct from MSA. Using cultured HEK cells expressing mutant α-synuclein (E46K), we found that DLB prions could be transmitted to these HEK cells. Our results argue that a third strain of α-synuclein prions likely causes PD, but further studies are needed to identify cells and/or Tg mice that express a mutant α-synuclein protein that is permissive for PD prion replication. Our findings suggest that other α-synuclein mutants should give further insights into α-synuclein prion replication, strain formation, and disease pathogenesis, all of which are likely required to discover effective drugs for the treatment of PD as well as the other α-synucleinopathies.

Accumulation of filamentous aggregates of tau protein in the brain is a pathological hallmark of Alzheimer's disease (AD) and many other neurodegenerative tauopathies. The filaments adopt disease-specific cross-β amyloid conformations that self-propagate and are implicated in neuronal loss. Development of molecular diagnostics and therapeutics is of critical importance. However, mechanisms of small molecule binding to the amyloid core is poorly understood. We used cryo-electron microscopy to determine a 2.7 Å structure of AD patient-derived tau paired-helical filaments bound to the PET ligand GTP-1. The compound is bound stoichiometrically at a single site along an exposed cleft of each protofilament in a stacked arrangement matching the fibril symmetry. Multiscale modeling reveals pi-pi aromatic interactions that pair favorably with the small molecule-protein contacts, supporting high specificity and affinity for the AD tau conformation. This binding mode offers critical insight into designing compounds to target different amyloid folds found across neurodegenerative diseases.

In microscopy-based drug screens, fluorescent markers carry critical information on how compounds affect different biological processes. However, practical considerations, such as the labor and preparation formats needed to produce different image channels, hinders the use of certain fluorescent markers. Consequently, completed screens may lack biologically informative but experimentally impractical markers. Here, we present a deep learning method for overcoming these limitations. We accurately generated predicted fluorescent signals from other related markers and validated this new machine learning (ML) method on two biologically distinct datasets. We used the ML method to improve the selection of biologically active compounds for Alzheimer's disease (AD) from a completed high-content high-throughput screen (HCS) that had only contained the original markers. The ML method identified novel compounds that effectively blocked tau aggregation, which had been missed by traditional screening approaches unguided by ML. The method improved triaging efficiency of compound rankings over conventional rankings by raw image channels. We reproduced this ML pipeline on a biologically independent cancer-based dataset, demonstrating its generalizability. The approach is disease-agnostic and applicable across diverse fluorescence microscopy datasets.

Parkinson's disease (PD) is a common neurodegenerative disorder without effective disease-modifying therapeutics. Here, we establish a chemogenetic dopamine (DA) neuron ablation model in larval zebrafish with mitochondrial dysfunction and robustness suitable for high-content screening. We use this system to conduct an in vivo DA neuron imaging-based chemical screen and identify the Renin-Angiotensin-Aldosterone System (RAAS) inhibitors as significantly neuroprotective. Knockdown of the angiotensin receptor 1 (agtr1) in DA neurons reveals a cell-autonomous mechanism of neuroprotection. DA neuron-specific RNA-seq identifies mitochondrial pathway gene expression that is significantly restored by RAAS inhibitor treatment. The neuroprotective effect of RAAS inhibitors is further observed in a zebrafish Gaucher disease model and Drosophila pink1-deficient PD model. Finally, examination of clinical data reveals a significant effect of RAAS inhibitors in delaying PD progression. Our findings reveal the therapeutic potential and mechanisms of targeting the RAAS pathway for neuroprotection and demonstrate a salient approach that bridges basic science to translational medicine.