Biology subjects

Saez-Mas, A.

Publications and source records attributed to Saez-Mas, A..

3 recordsLinked to original sources

bioRxiv2026

Modulation of retroviral capsid assembly halts ARC-mediated TDP-43 intercellular spreading

Intercellular propagation of pathological TDP-43 drives the progression of ALS and FTD, yet the mechanisms enabling transmission remain elusive. Here, we demonstrate that Activity-regulated cytoskeleton associated protein (ARC/Arg3.1) is pathologically subverted to act as a retroviral-like capsid vehicle for TDP-43 spreading. In a Drosophila model, we reveal that massive Arc1 upregulation drives glia-to-neuron TDP-43 seeding, while its genetic ablation halts pathological transfer, improves motor function, and extends survival. In parallel human cellular models, stress-induced ARC colocalizes with TDP-43 to orchestrate its intercellular transmission. Guided by ARCs capsid architecture, we reproposed Lenacapavir, an FDA-approved HIV-1 capsid modulator, as a stable binder of ARC/Arg3.1 capsid interfaces. Lenacapavir treatment effectively blocks TDP-43 propagation in vitro and rescues disease phenotypes in vivo. Our findings establish ARC as a conserved vehicle for pathological protein transmission and deliver an immediately translatable pharmacological strategy to arrest disease progression in ALS and FTD.

neuroscience↗

bioRxiv2026

The accumulation of orphan ribosomal proteins is a hallmark of ALS

Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disease of poor prognosis, for which age is the strongest risk factor. Despite significant progress in the discovery of ALS-associated mutations, no model explains how such a diversity of mutations converges in a common pathology. In addition, most ALS cases are sporadic and lack known genetic drivers. We recently reported that arginine-rich peptides arising from the C9ORF72 mutation trigger a widespread accumulation of orphan ribosomal proteins (oRP). Here, we show that oRP accumulation is also observed upon expression of other RNA-related ALS mutations, such as hnRNPA2D290V and TDP-43A315T, as well as upon exposure to the ALS-related neurotoxin {beta}-N-methylamino-L-alanine (BMAA). Furthermore, the transcriptional signature of patients with sporadic ALS resembles that of Diamond-Blackfan anemia (DBA), a known ribosomopathy. Supporting the usefulness of our in vitro data, a transcriptional signature defined from these models provides diagnostic and prognostic value in ALS patients. We propose that the accumulation of oRPs due to dysfunctional ribosome biogenesis is a molecular hallmark of ALS that can contribute to the progressive loss of motor neurons in the disease.

neuroscience↗

bioRxiv2026

A chemical inducer of ribophagy limits the toxicity of ALS-related arginine-rich peptides

C9ORF72 intronic repeat expansions are the most frequent mutation found in Amyotrophic Lateral Sclerosis (ALS), producing toxic arginine-rich dipeptides (DPR) that disrupt RNA metabolism and trigger the accumulation of orphan ribosomal proteins (RP). Through a large phenotypic chemical screen, we identified "SALSa", a novel compound that mitigates DPR toxicity. Mechanistically, SALSa acts as a chemical inducer of ribophagy, a specialized form of autophagy that promotes RP clearance. Interestingly, this effect is unrelated to mTOR inhibition, the main regulator of autophagy. In contrast, this is due to an effect of the drug in ribosome biogenesis, which triggers a protective response to clear defective ribosomes. Accordingly, SALSa accumulates in nucleoli and perturbs the final steps of rRNA maturation. SALSa reduces DPR toxicity in differentiated neurons and significantly extends lifespan in a Drosophila melanogaster model of C9ORF72 ALS. These findings suggest that stimulating ribophagy could be beneficial for pathologies associated to dysfunctional ribosome biogenesis, including C9ORF72 ALS.

molecular biology↗