The induced pluripotent stem (iPS) cell field promises a new era for in vitro disease modeling. However, identifying innate cellular pathologies, particularly for age-related neurodegenerative diseases, has been challenging. Here, we exploited mutation correction of iPS cells and conserved proteotoxic mechanisms from yeast to human to discover and reverse phenotypic responses to α-Synuclein (αSyn), a key protein involved in Parkinson’s disease (PD). We generated cortical neurons from iPS cells of patients harboring αSyn mutations, who are at high risk of developing PD dementia. Genetic modifiers from unbiased screens in a yeast model of αSyn toxicity led to identification of early pathogenic phenotypes in patient neurons. These included nitrosative stress, accumulation of ER-associated degradation (ERAD) substrates and ER stress. A small molecule identified in a yeast screen, and the ubiquitin ligase Nedd4 it activates, reversed pathologic phenotypes in these neurons.

α–synuclein (α-syn) is a small lipid binding protein implicated in several neurodegenerative diseases, including Parkinson’s disease, whose pathobiology is conserved from yeast to man. There are no therapies targeting these underlying cellular pathologies, or indeed those of any major neurodegenerative disease. Using unbiased phenotypic screens as an alternative to target-based approaches, we discovered an N-aryl benzimidazole (NAB) that strongly and selectively protected diverse cell-types from α-syn toxicity. Three chemical genetic screens in wild-type yeast cells established that NAB promoted endosomal transport events dependent on the E3 ubiquitin ligase, Rsp5/Nedd4. These same steps were perturbed by α–syn itself. Thus, NAB identifies a druggable node in the biology of α-syn that can correct multiple aspects of its underlying pathology, including dysfunctional endosomal and ER-to-Golgi vesicle trafficking.

We developed an effective method for reductive radical formation that utilizes the radical anion of carbon dioxide (CO 2•− ) as a powerful single electron reductant. Through a polarity matched hydrogen atom transfer (HAT) between an electrophilic radical and a formate salt, CO 2•− formation occurs as a key element in a new radical chain reaction. Here, radical chain initiation can be performed through photochemical or thermal means, and we illustrate the ability of this approach to accomplish reductive activation of a range of substrate classes. Specifically, we employed this strategy in the intermolecular hydroarylation of unactivated alkenes with (hetero)aryl chlorides/bromides, radical deamination of arylammonium salts, aliphatic ketyl radical formation, and sulfonamide cleavage. We show that the reactivity of CO 2•− with electron-poor olefins results in either single electron reduction or alkene hydrocarboxylation, where substrate reduction potentials can be utilized to predict reaction outcome.

Edited by Norma AllewellLiver receptor homolog 1 (NR5A2, LRH-1) is an orphan nuclear hormone receptor that regulates diverse biological processes, including metabolism, proliferation, and the resolution of endoplasmic reticulum stress. Although preclinical and cellular studies demonstrate that LRH-1 has great potential as a therapeutic target for metabolic diseases and cancer, development of LRH-1 modulators has been difficult. Recently, systematic modifications to one of the few known chemical scaffolds capable of activating LRH-1 failed to improve efficacy substantially. Moreover, mechanisms through which LRH-1 is activated by synthetic ligands are entirely unknown. Here, we use x-ray crystallography and other structural methods to explore conformational changes and receptor-ligand interactions associated with LRH-1 activation by a set of related agonists. Unlike phospholipid LRH-1 ligands, these agonists bind deep in the pocket and do not interact with residues near the mouth nor do they expand the pocket like phospholipids. Unexpectedly, two closely related agonists with similar efficacies (GSK8470 and RJW100) exhibit completely different binding modes. The dramatic repositioning is influenced by a differential ability to establish stable face-to-face --stacking with the LRH-1 residue His-390, as well as by a novel polar interaction mediated by the RJW100 hydroxyl group. The differing binding modes result in distinct mechanisms of action for the two agonists. Finally, we identify a network of conserved water molecules near the ligand-binding site that are important for activation by both agonists. This work reveals a previously unappreciated complexity associated with LRH-1 agonist development and offers insights into rational design strategies.Liver receptor homolog 1 (LRH-1; NR5A2) is a nuclear hormone receptor (NR) 3 that controls expression of a diverse set of genes important both in normal physiology and disease. In addition to a vital role during development (1, 2), LRH-1 regulates many genes related to metabolism, proliferation, and cell survival. In the liver, LRH-1 regulates bile acid biosynthesis (3) and reverse cholesterol transport (4, 5), affecting hepatic and circulating cholesterol levels. Glucose metabolism is also regulated by LRH-1 at several points, including GLUT-4-mediated transport (6) and glucose phosphorylation, the latter of which is essential for proper postprandial glucose sensing, flux through glycolysis and glycogenesis pathways, and de novo lipogenesis (7). LRH-1 is a key mediator of the cell stress response through control of genes involved in the hepatic acute phase response (8) and in the cytoprotective resolution of endoplasmic reticulum stress (9). Additionally, LRH-1 can be aberrantly overexpressed in certain cancers and can promote tumor growth through estrogen receptor and ␤-catenin signaling (10 -16).Considering the breadth and significance of these physiological effects, LRH-1 modulators are highly desired as potential therapeutic agents. Chemical modulators would al...

Fluorinated organic molecules are pervasive within the pharmaceutical and agrochemical industries due to the range of structural and physicochemical properties that fluorine imparts. Currently, the most abundant methods for the synthesis of the aryl-CF 2 functionality have relied on the deoxyfluorination of ketones and aldehydes using expensive and poorly atom economical reagents. Here, we report a general method for the synthesis of aryl-CF 2 R and aryl-CF 2 H compounds through activation of the corresponding trifluoromethyl arene precursors. This strategy is enabled by an endergonic electron transfer event that provides access to arene radical anions that lie outside of the catalyst reduction potential. Fragmentation of these reactive intermediates delivers difluorobenzylic radicals that can be intercepted by abundant alkene feedstocks or a hydrogen atom to provide a diverse array of difluoalkylaromatics.