Biology subjects

Mansilla, A.

Publications and source records attributed to Mansilla, A..

6 recordsLinked to original sources

bioRxiv2026

The genomic basis of evolutionary stasis in the 500-million-year-old red seaweed genus Ahnfeltia

The red seaweed genus Ahnfeltia is an ancient lineage that has persisted for over 500 million years with remarkably limited diversification despite a global distribution in cold-temperate intertidal habitats. Compared to the highly diverse sister lineage, Rhodymeniophycidae, Ahnfeltia provides a unique system for investigating long-term evolutionary persistence in marine macroalgae. Here, we generated chromosome-scale genomes from five populations across three species and combined population genomics with paleogeographic niche modelling. Our results reveal remarkable genomic conservation, strong geographic isolation with limited gene flow, high homozygosity, and evidence of purifying selection. Niche projections indicate long-term stability and spatial connectivity of suitable cold-temperate habitats. These findings suggest that Ahnfeltias persistence and limited diversification are linked to genomic constraints and stable ecological niches over geological timescales. This study provides new insights into the genomic basis of evolutionary stasis in ancient marine lineages and highlights potential vulnerability to ongoing climate change affecting cold-water coastal ecosystems.

evolutionary biology↗

bioRxiv2025

Leveraging crystallographic fragment screening, algorithmic merging and digital chemistry to target NCS-1 protein-protein interactions for treatment of neurological disorders

Efficient drug discovery relies on workflows that integrate structural insights with rapid and cost-effective exploration of chemical space. Here, we present a data-driven fragment-based lead discovery approach to target Neuronal Calcium Sensor 1 (NCS-1) protein-protein interactions (PPIs). This study represents a complete implementation of a single high-value design-make-test-analyze cycle that directly yields compounds with micromolar affinity with the potential to modulate NCS-1 interactions with key targets, including the G-protein chaperone Ric-8A and the dopamine D2 and cannabinoid CB1 receptors. X-ray crystallographic fragment screening (CFS) revealed diverse interaction patterns within the NCS-1 hydrophobic crevice. Algorithmically guided fragment evolution and automated synthesis enabled the rapid generation of over 250 derivatives, with biophysical validation using LC-MS and Grating-coupled interferometry. Structural analyses highlighted key pharmacophores, with selected compounds exhibiting favorable drug-like properties and potential blood-brain barrier penetration, making them promising candidates for neurodegenerative and neurodevelopmental disorders. Our results demonstrate the feasibility of accelerated hit-to-lead development at synchrotrons, demonstrating a robust, scalable platform for PPI-targeting drug discovery. The generated chemically diverse scaffolds provide a strong foundation for future therapeutic optimization.

biophysics↗

bioRxiv2025

FDA drug repurposing uncovers modulators of dopamine D2 receptor localization via disruption of the NCS-1 interaction

Dopamine D2 receptor (D2R) regulates key aspects of motor control, cognition, and reward. Its function depends not only on ligand binding and signaling efficacy, but also on the dynamic control of receptor localization at the cell surface. Neuronal Calcium Sensor 1 (NCS-1) is a calcium binding protein which directly interacts with D2R in a Ca2+-dependent manner. Here, we investigated the regulatory role of NCS-1 in D2R localization and function. We found that NCS-1 promotes the trafficking of D2R to the plasma membrane through a mechanism dependent on active exocytosis. Functional signaling assays confirmed that NCS-1 does not alter the canonical receptor pharmacology. Using a library of FDA-approved drugs, a structure-based drug-repurposing strategy was designed to find protein-protein interaction modulators that allowed the exploration of the NCS-1/D2R interface as a new pharmacological target. Azilsartan medoxomil, atorvastatin, and vilazodone disrupted its interaction with D2R, reducing receptor surface expression in cells. Crystallography and molecular dynamics simulations revealed their mechanism of action. These compounds target the NCS-1 hydrophobic crevice and overlap the D2R binding site, perturbing the dynamics of the regulatory helix H10 in NCS-1. These findings uncover a previously unexploited intracellular mechanism for modulating D2R function and highlight the potential of targeting protein-protein interactions for therapeutic purposes. Our results provide a framework for fine-tuning dopaminergic tone through receptor localization mechanisms, offering an alternative strategy to conventional approaches based on receptor blockade or direct agonism. SIGNIFICANCEFDA-approved drugs targeting the calcium sensor NCS-1 selectively disrupt its interaction with the dopamine D2 receptor, offering a new strategy to modulate receptor trafficking without altering receptor signaling.

biochemistry↗

bioRxiv2022

The neuronal calcium sensor NCS-1 regulates the phosphorylation state and activity of the Gα chaperone and GEF Ric-8A

The Neuronal Calcium Sensor 1 and Ric-8A coregulate synapse number and probability of neurotransmitter release. Recently, the structures of Ric-8A bound to G have revealed how Ric-8A phosphorylation promotes G recognition and activity as a chaperone and guanine nucleotide exchange factor. However, the molecular mechanism by which NCS-1 regulates Ric-8A activity and its interaction with G subunits is not well understood. Given the interest in the NCS-1/Ric-8A complex as a therapeutic target in nervous system disorders, it is necessary to shed light on this molecular mechanism of action at atomic level. We have reconstituted NCS-1/Ric-8A complexes to conduct a multimodal approach and determine the sequence of Ca2+ signals and phosphorylation events that promote the interaction of Ric-8A with G. Our data show that the binding of NCS-1 and G to Ric-8A are mutually exclusive. Importantly, NCS-1 induces a profound structural rearrangement in Ric-8A that traps the protein in a conformational state that is inaccessible to Casein Kinase II-mediated phosphorylation, demonstrating one aspect of its negative regulation of Ric-8A-mediated G-protein signaling. Functional experiments indicate a loss of Ric-8A GEF activity towards G when complexed with NCS-1, and restoration of nucleotide exchange activity upon increasing Ca2+ concentration. Finally, the high-resolution crystallographic data reported here that define the NCS-1/Ric-8A interface will allow the development of therapeutic synapse function regulators with improved activity and selectivity.

biochemistry↗

bioRxiv2021

Inhibition of the sodium-dependent HCO3 -transporter SLC4A4, produces a cystic fibrosis-like airway disease phenotype.

Bicarbonate secretion is a fundamental process involved in maintaining acid-base homeostasis. Disruption of bicarbonate entry into airway lumen, as has been observed in cystic fibrosis, produces several defects in lung function due to thick mucus accumulation. Bicarbonate is critical for correct mucin deployment and there is increasing interest in understanding its role in airway physiology, particularly in the initiation of lung disease in children affected by cystic fibrosis, in the absence of detectable bacterial infection. The current model of anion secretion in mammalian airways consists of CFTR and TMEM16A as apical anion exit channels, with limited capacity for bicarbonate transport compared to chloride. However, both channels can couple to SLC26A4 anion exchanger to maximise bicarbonate secretion. Nevertheless, current models lack any details about the identity of the basolateral protein(s) responsible for bicarbonate uptake into airway epithelial cells. We report herein that the electrogenic, sodium-dependent, bicarbonate cotransporter, SLC4A4, is expressed in the basolateral membrane of human and mouse airways, and that its pharmacological inhibition or genetic silencing reduces bicarbonate secretion. In fully differentiated primary human airway cells, SLC4A4 inhibition induced an acidification of the airways surface liquid and markedly reduced the capacity of cells to recover from an acid load. Studies in the Slc4a4-null mice revealed a previously unreported lung phenotype, characterized by mucus accumulation and reduced mucociliary clearance. Collectively, our results demonstrate that the reduction of SLC4A4 function induced a CF-like phenotype, even when chloride secretion remained intact, highlighting the important role SLC4A4 plays in bicarbonate secretion and mammalian airway function.

physiology↗

bioRxiv2020

Tamoxifen reduces inflammatory infiltration of neutrophils in the airways.

ABSTRACTTamoxifen is a drug of choice for treatment of breast cancer but it has also been reported to bear anti-inflammatory activity. Previously, we have observed that tamoxifen treatment successfully reduced inflammation in horses affected by equine asthma syndrome. More notorious, tamoxifen was effective at reducing the infiltration of neutrophils in the inflamed airways by a mechanism that increases efferocytosis, allowing the resolution of inflammation. Due to the emerging increase in patients with chronic inflammatory lung diseases, there is an urgent need for therapies that help reduce airway inflammation. Thus we tested the effect of tamoxifen on airway neutrophil infiltration by using three different mouse models for acute and chronic inflammation of the lung. We found that the drug was able to produce a significant reduction in neutrophils in all scenarios. Ussing chamber experiments demonstrated that tamoxifen has no effect on fluid secretion and absorption, discarding a possible reduction in mucociliary clearance due to the known ion-channel blocking effects of tamoxifen. Since this drug has been largely used in human medicine, tamoxifen might be a “low hanging fruit” for a novel anti-inflammatory therapy for airway diseases characterized by neutrophilic inflammation.Competing Interest StatementThe authors have declared no competing interest.View Full Text

pharmacology and toxicology↗