Biology subjects

Djouad, F.

Publications and source records attributed to Djouad, F..

5 recordsLinked to original sources

bioRxiv2025

Metabolic rewiring of cancer cells induces metastasis via ERK5 but triggers recognition by NK cells

Metastasis is largely controlled by Natural Killer (NK) cell-mediated immune surveillance. To colonize new environments, cancer cells undergo epithelial to mesenchymal transition (EMT), which allows them to detach and migrate. EMT is fueled by fatty acid oxidation (FAO), which partially replaces glycolytic-based tumor metabolism. Whether metabolic rewiring affects the targeting of cancer cells by NK cells remains unknown. Here, we show that forcing solid cancer cells to perform FAO by inhibiting pyruvate dehydrogenase kinase 1 with dichloroacetate (DCA) activates extracellular signal-regulated kinase-5 (ERK5), triggering EMT and tumor cell migration and invasion. Concomitantly, FAO induces the expression of ligands that mediate NK cell recognition. Consequently, NK cells better infiltrated DCA-treated 3D tumor spheroids, where they exerted their cytotoxic effects. DCA-treated cells showed increased migration in a zebrafish model, whereas metastasis from mammary cancer cells grafted into immune-deficient mice was enhanced by DCA. These migrating/metastatic cells are preferentially killed by NK cells, which strongly limit their invasive potential. Hence, FAO promotes both metastasis and NK-mediated tumor surveillance, highlighting the Achilles heel of metastatic cells, which may offer new therapeutic opportunities. TeaserMetastasis recognition and killing by immune cells, such as NK cells, requires a metabolic shift that relies on lipid metabolism.

cancer biology↗

bioRxiv2025

Functional Equivalence of the Proneural Genes Neurog1 and Neurog2 in the Developing Dorsal Root Ganglia Highlights the Importance of Timing of Neurogenesis in Biasing Somatosensory Precursor Fates

Distinct subfamilies of proneural bHLH transcription factors (TFs) control neurogenesis and influence neuronal fate specification throughout the developing nervous system. While members of different subfamilies generally display divergent expression and functions, those within the same subfamily are often co-expressed, raising questions about their respective roles. Here, we assess the functional equivalence of the two paralogous proneural TFs Neurog1 and Neurog2, focusing on neurons of the dorsal root ganglia (DRG) which underlie our ability to process somatosensory information. During development, distinct classes of DRG neurons -classified as mechano/proprioceptors or thermo/nociceptors-are generated during two successive neurogenic phases, which are respectively controlled by Neurog2 and Neurog1, in line with their dynamic and complementary spatiotemporal expression patterns. Therefore, in this system, each TF appears to play unique roles in regulating neurogenesis and specifying distinct neuronal identities. Yet, using a gene replacement strategy in vivo, we show that, despite subtle divergences masked by dose-compensation effects, Neurog1 and Neurog2 are essentially functionally interchangeable in all aspects of DRG development, indicating that their apparent functional discrepancies primarily stem from divergent evolution of their gene regulatory regions, rather than of their respective biochemical properties. Notably, we definitively establish that neither TF directly specifies specific somatosensory neuron identities. This result, combined with : (i) a new series of birth-dating experiments supporting that most mechano/proprioceptive and thermo/nociceptive subtypes are predominantly born during successive time-windows; and (ii) analyses of complementary transgenic mouse models in which opposite temporal shifts of neurogenesis -either delayed onset or premature arrest-have predictable opposite impacts on their DRG content, highlight that the fate choice of somatosensory precursors toward the mechano/proprioceptive or thermo/nociceptive lineages critically depends on the timing of their birth.

developmental biology↗

bioRxiv2023

Microencapsulation of mesenchymal stromal cells in covalent alginate hydrogels for cell therapy

Osteoarthritis (OA) is the most common inflammatory joint disease and currently lacks an effective curative treatment. Intra-articular injection of mesenchymal stromal cells (MSCs) has gained attention as a relevant therapeutic approach for OA treatment due to the MSCs ability to secrete anti-inflammatory and immunomodulatory factors. Given their limited viability post- intraarticular injection and the potential leakage of cells out of the injection site, encapsulating MSCs in hydrogels is considered a promising strategy to protect them and provide a suitable 3D microenvironment to support their biological activities. Calcium-cross-linked alginate hydrogels are commonly used for MSC encapsulation, but their long-term in vivo stability remains uncertain. On the other hand, alginate cross-linking by the strain-promoted azide- alkyne cycloaddition (SPAAC) reaction would create a network unaffected by an ionic environment. Hence, this study aimed to develop an alginate-based hydrogel cross-linked via stable and cytocompatible covalent bonds for cell encapsulation. We established for the first time the formation of covalent alginate hydrogels between two SPAAC precursors, namely alginate-BCN and alginate-N3. These hydrogels exhibited in vitro stability and enabled the diffusion of molecules of interest. We then generated alginate-based SPAAC microgels of 170 m in mean diameter, suitable for intra-articular injection. We next encapsulated human adipose MSCs (hASCs) in these alginate-based SPAAC microgels and confirmed their cytocompatibility, with over 90 % of cells remaining viable after 14 days in culture. Finally, the microencapsulated hASCs maintained their biological properties and were able to secrete anti-inflammatory factors (IDO, PGE2, and HGF) when exposed to pro-inflammatory cytokines (TNF- and IFN-{gamma}). In the end, human-activated lymphocytes were cultured in contact with microencapsulated hASCs, and CD3+ T cell proliferation was quantified by flow cytometry. We demonstrated that the encapsulation process did not impair the hASC immunomodulatory activity. Overall, our findings show the potential of alginate-based SPAAC hydrogels for microencapsulating hASCs for cell therapy.

bioengineering↗

bioRxiv2023

PLOD2, a key factor for MRL MSC metabolism and chondroprotective properties

BackgroundInitially discovered for its ability to regenerate ear holes, the MRL mouse has been the subject of multiple research studies aimed at evaluating its ability to regenerate other body tissues and at deciphering the mechanisms underlying it. These enhanced abilities to regenerate, retained in the adult, protect the MRL mouse from degenerative diseases such as osteoarthritis (OA). Here, we hypothesized that MSC derived from the regenerative MRL mouse could be involved in their regenerative potential through the release of pro-regenerative mediators. MethodTo address this hypothesis, we compared the secretome of MRL and BL6 MSC and identified several candidate molecules produced at significantly higher levels by MRL MSC than by BL6 MSC. We selected one candidate and performed functional in vitro assays to evaluate its role on MRL MSC properties including metabolic profile, migration, and chondroprotective effects. Using an experimental model for osteoarthritis (OA) induced by collagenase (CiOA), we assessed its contribution to MRL MSC protection from OA. ResultsAmong the candidate molecules highly expressed by MRL MSC, we focused our attention on procollagen-lysine,2-oxoglutarate 5-dioxygenase 2 (PLOD2), coding for the lysyl hydrolase LH2 in charge of post-translational modifications of collagen for its stability and stiffness. PLOD2 is induced by hypoxia-inducible factor 1-alpha (HIF-1a) involved in the regeneration process of adult MRL mice. Plod2 silencing induced a decrease in the glycolytic function of MRL MSC, resulting in the alteration of their migratory and chondroprotective abilities in vitro. In vivo, we showed that plod2 silencing in MRL MSC significantly impaired their capacity to protect mouse from developing OA. ConclusionOur results demonstrate that the chondroprotective and therapeutic properties of MRL MSC in the CiOA experimental model are in part mediated by PLOD2.

cell biology↗

bioRxiv2020

Detailed analysis of public RNAseq data and longnon-coding RNA: a proposed enhancement to mesenchymalstem cell characterisation

The development of RNA sequencing (RNAseq) and corresponding emergence of public datasets have created new avenues of transcriptional marker search. The long non-coding RNAs (lncRNAs) constitute an emerging class of transcripts with a potential for high tissue specificity and function. Using a dedicated bioinformatics pipeline, we propose to construct a cell-specific catalogue of unannotated lncRNAs and to identify the strongest cell markers. This pipeline uses ab initio transcript identification, pseudoalignment and new methodologies such as a specific k-mer approach for naive quantification of expression in numerous RNAseq data. For an application model, we focused on Mesenchymal Stem Cells (MSCs), a type of adult multipotent stem-cells of diverse tissue origins. Frequently used in clinics, these cells lack extensive characterisation. Our pipeline was able to highlight different lncRNAs with high specificity for MSCs. In silico methodologies for functional prediction demonstrated that each candidate represents one specific state of MSCs biology. Together, these results suggest an approach that can be employed to harness lncRNA as cell marker, showing different candidates as potential actors in MSCs biology, while suggesting promising directions for future experimental investigations.

genomics↗