Joan Torrent

Neurodevelopmental conditions, including attention deficit hyperactivity disorder (ADHD) and autism spectrum disorders (ASD), have increased markedly over recent decades. This rise parallels the widespread use of agrochemicals, suggesting a contribution of environme ntal exposures. We hypothesize that pesticide residues may disrupt brain development and promote neurodevelopmental disorders. Here, we test whether concentrations permitted in drinking water affect brain development using a maternal exposure model in wild-type mice. Exposure to a fungicide mixture at 0.3 µg/L, below the current European regulatory limit of 0.5 µg/L, impairs corticogenesis and is associated with alterations in synaptic function and glutamate rgic signaling. Offspring exhibit delays in sensory development, reduced social interactions, and increased stereotyped behaviors. We identify the adenosine A2A receptor as a molecular target of anilinopyrimidine fungicides. Together, these findings indicate that low-dose exposure to this fungicide mixture can induce an autism spectrum-like phenotype in the offspring.

The prion paradigm is founded on the transmission of structural information from aggregated assemblies to soluble protein substrates, a process classically attributed to fibril-end-mediated templating. Whether non-fibrillar assemblies or transient oligomeric states can also participate in folding information transfer remains unclear. Here, using recombinant prion protein (PrP), rational mutagenesis, hetero-oligomerization assays, arrested reaction conditions, and single-particle atomic force microscopy coupled to infrared nano-spectroscopy (AFM-IR), we examine the earliest stages of PrP assembly from the perspective of folding information transmission. We show that polymerization-defective PrP variants can be incorporated into oligomeric assemblies through structural complementation, in which folding information supplied by wild-type PrP restores their assembly competence. Under arrested reaction conditions, transient polymerization-competent conformers further contribute to folding information transfer at subcritical concentrations. Domain-resolved analyses reveal a modular oligomeric architecture in which a β-sheet-rich B domain constitutes the primary scaffold for folding information transfer. Preformed O1 oligomers then act as autonomous conformational templates that promote mutant incorporation and undergo hierarchical condensation through accretion of a structurally distinct E domain. Together, these findings demonstrate that non-fibrillar PrP oligomers and transient assembly intermediates can store and transmit folding information and may function as oligomer-based secondary nucleation platforms, expanding the conceptual framework of prion assembly beyond fibril-end elongation alone.

Reg-1α/lithostathine, a protein mainly associated with the digestive system, was previously shown to be overexpressed in the pre-clinical stages of Alzheimer’s disease. In vitro, the glycosylated protein was reported to form fibrils at physiological pH following the proteolytic action of trypsin. However, the nature of the protease able to act in the central nervous system is unknown. In the present study, we showed that Reg-1α can be cleaved in vitro by calpain-2, the calcium activated neutral protease, overexpressed in neurodegenerative diseases. Using chemical crosslinking experiments, we found that the two proteins can interact with each other. Identification of the cleavage site using mass spectrometry, between Gln⁴ and Thr⁵, was found in agreement with the in silico prediction of the calpain cleavage site, in a position different from the one reported for trypsin, i.e., Arg¹¹-Ile¹² peptide bond. We showed that the cleavage was impeded by the presence of the neighboring glycosylation of Thr⁵. Moreover, in vitro studies using electron microscopy showed that calpain-cleaved protein does not form fibrils as observed after trypsin cleavage. Collectively, our results show that calpain-2 cleaves Reg-1α in vitro, and that this action is not associated with fibril formation.

Discovered more than a century ago, Alzheimer’s disease (AD) is not only still present in our societies but has also become the most common dementia, with 50 million people worldwide affected by the disease. This number is expected to double in the next generation, and no cure is currently available to slow down or stop the disease progression. Recently, some advances were made due to the approval of the aducanumab treatment by the American Food and Drug Administration. The etiology of this human-specific disease remains poorly understood, and the mechanisms of its development have not been completely clarified. Several hypotheses concerning the molecular mechanisms of AD have been proposed, but the existing studies focus primarily on the two main markers of the disease: the amyloid β peptides, whose aggregation in the brain generates amyloid plaques, and the abnormally phosphorylated tau proteins, which are responsible for neurofibrillary tangles. These protein aggregates induce neuroinflammation and neurodegeneration, which, in turn, lead to cognitive and behavioral deficits. The challenge is, therefore, to create models that best reproduce this pathology. This review aims at gathering the different existing AD models developed in vitro, in cellulo, and in vivo. Many models have already been set up, but it is necessary to identify the most relevant ones for our investigations. The purpose of the review is to help researchers to identify the most pertinent disease models, from the most often used to the most recently generated and from simple to complex, explaining their specificities and giving concrete examples.

Single nanopore is a powerful platform to detect, discriminate and identify biomacromolecules. Among the different devices, the conical nanopores obtained by the track-etched technique on a polymer film are stable and easy to functionalize. However, these advantages are hampered by their high aspect ratio that avoids the discrimination of similar samples. Using machine learning, we demonstrate an improved resolution so that it can identify short single- and double-stranded DNA (10- and 40-mers). We have characterized each current blockade event by the relative intensity, dwell time, surface area and both the right and left slope. We show an overlap of the relative current blockade amplitudes and dwell time distributions that prevents their identification. We define the different parameters that characterize the events as features and the type of DNA sample as the target. By applying support-vector machines to discriminate each sample, we show accuracy between 50% and 72% by using two features that distinctly classify the data points. Finally, we achieved an increased accuracy (up to 82%) when five features were implemented.

Environmental Health Perspectives is an Open Access journal published by the National Institute of Environmental Health Sciences. Environmental Health Perspectives is an Open Access journal published by the National Institute of Environmental Health Sciences.

Dysregulation of the hypothalamic‐pituitary‐adrenal (HPA) axis occurs early in Alzheimer's disease (AD), associated with elevated circulating glucocorticoids (GC) and glucocorticoid receptors (GR) signaling impairment. However, the precise role of GR in the pathophysiology of AD remains unclear. Using an acute model of AD induced by the intracerebroventricular injection of amyloid‐β oligomers (oAβ), we analyzed cellular and behavioral hallmarks of AD, GR signaling pathways, processing of amyloid precursor protein, and enzymes involved in Tau phosphorylation. We focused on the prefrontal cortex (PFC), particularly rich in GR, early altered in AD and involved in HPA axis control and cognitive functions. We found that oAβ impaired cognitive and emotional behaviors, increased plasma GC levels, synaptic deficits, apoptosis and neuroinflammatory processes. Moreover, oAβ potentiated the amyloidogenic pathway and enzymes involved both in Tau hyperphosphorylation and GR activation. Treatment with a selective GR modulator (sGRm) normalized plasma GC levels and all behavioral and biochemical parameters analyzed. GR seems to occupy a central position in the pathophysiology of AD. Deregulation of the HPA axis and a feed‐forward effect on PFC GR sensitivity could participate in the etiology of AD, in perturbing Aβ and Tau homeostasis. These results also reinforce the therapeutic potential of sGRm in AD.

Image analysis of protein fibrils is a key step for a quantitative understanding of the mechanisms responsible for aggregation and deposition of amyloids. In this paper, we develop a fully automated method to detect and measure all characteristics of fibrils. After detecting the fibrils centerline, we propose a tracking-based method to estimate the local width, length and curvature of fibrils. We also discriminate between branches and overlapping of fibrils by comparing the orientations of the fibril segments at their intersection point. We test our method on Transmission Electron Microscopy (TEM) images of human, bank vole, and ovine PrP (prion protein) fibrils, and analyze the result to evidence structural differences between different types of fibrils. The proposed method has high estimation accuracy in detections and is further compared with a state-of-art method.