Biology subjects

Lacombe, A.

Publications and source records attributed to Lacombe, A..

3 recordsLinked to original sources

bioRxiv2025

TDP-43 pathology triggers SRRM4-dependent cryptic splicing of G3BP1 in ALS/FTD

Loss of nuclear TDP-43 is a defining feature of the neurodegenerative diseases amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD), yet how this leads to selective neuronal vulnerability is poorly understood. Here, using human iPSC-derived neurons and a large multi-omics dataset of ALS/FTD patients, we demonstrate that TDP-43 pathology induces the inclusion of an in-frame cryptic exon in human G3BP1. The resulting CRYPTIC G3BP1 protein contains an additional 10-amino acids within the highly conserved NTF2L domain, which acts as a dominant negative and disrupts stress granule dynamics. We further show that cryptic exon inclusion in G3BP1 upon TDP-43 loss is enriched in neurons. Mechanistically, the loss of TDP-43 unmasks a binding site for the neuron-specific splicing regulator SRRM4 within intron 2 of G3BP1, enabling the inclusion of the cryptic exon. Collectively, our findings reveal that neuron-specific regulatory mechanisms intersect with TDP-43 -mediated splicing and suggest a mechanistic basis for the increased neuronal vulnerability observed in ALS/FTD.

neuroscience↗

bioRxiv2020

Tolerogenic Dendritic Cells Shape a Transmissible Gut Microbiota that Protects from Metabolic Diseases

Excess of chronic contact between microbial motifs and intestinal immune cells are known to trigger a low-grade inflammation involved in many pathologies such as obesity and diabetes. The important skewing of intestinal adaptive immunity in the context of diet-induced obesity (DIO) is well described but how dendritic cells (DCs) participate to these changes is still poorly documented. To address this question, transgenic mice with enhanced DCs lifespan and immunogenicity (DChBcl-2 mice), are challenged with a high fat diet. Those mice display resistance to DIO and metabolic alterations. The DIO resistant phenotype is associated with healthier parameters of intestinal barrier function and lower intestinal inflammation. DChBcl-2 DIO-resistant mice demonstrate a particular increase in tolerogenic DC numbers and function which is associated with strong intestinal IgA, Th17 and T regulatory immune responses. Microbiota composition and function analyses reveal that the DChBcl-2 mice microbiota is characterized by a lower immunogenicity and an enhanced butyrate production. Cohousing experiments and fecal microbial transplantations are sufficient to transfer the DIO resistance status to WT mice demonstrating that maintenance of DCs tolerogenic ability sustains a microbiota able to drive DIO resistance. DCs tolerogenic function is revealed as a new potent target in metabolic diseases management.

immunology↗

bioRxiv2019

In silico screen identifies a new Toxoplasma gondii mitochondrial ribosomal protein essential for mitochondrial translation

Apicomplexan parasites cause diseases such as malaria and toxoplasmosis. The apicomplexan mitochondrion shows striking differences from common model organisms, including in fundamental processes such as mitochondrial translation. Despite evidence that mitochondrial translation is essential for parasites survival, it is largely understudied. Progress has been restricted by the absence of functional assays to detect apicomplexan mitochondrial translation, a lack of knowledge of proteins involved in the process and the inability to identify and detect mitoribosomes. Using mRNA expression patterns, 279 candidate mitochondrial housekeeping components were identified in Toxoplasma. 11 were validated, including the mitoribosomal small subunit protein 35 (TgmS35). TgmS35 tagging enabled the detection of a macromolecular complex corresponding to the mitoribosomal small subunit for the first time in apicomplexans. A new analytical pipeline detected defects in mitochondrial translation upon TgmS35 depletion, while other mitochondrial functions remain unaffected. Our work lays a foundation for the study of apicomplexan mitochondrial translation. Abbreviated summaryThe apicomplexan mitochondrion is divergent and essential yet poorly studied. Mitochondrial translation is predicted to utilize ribosomes assembled from fragmented rRNA but this was never shown. Knowing the mitochondrial protein content is critical for these studies. We identified 11 new mitochondrial proteins via in-silico searches. Tagging and depletion of a mitoribosomal small subunit protein enabled the first detection of a macromolecular ribosomal complex, and provided proof of principle for our new mitochondrial translation analytic pipeline.

cell biology↗