Biology subjects

Pichon, C.

Publications and source records attributed to Pichon, C..

3 recordsLinked to original sources

bioRxiv2026

Affinity-enhanced peptides delivered by mRNA lipid nanoparticles inhibit influenza A virus replication by disrupting PA-PB1 interaction

Seasonal influenza causes up to 650,000 deaths annually and remains a persistent pandemic threat due to zoonotic strains crossing the species barrier. Current antivirals, which target neuraminidase or the viral polymerase, have limited efficacy and rapidly select for resistant variants, highlighting the urgent need for new therapeutic strategies. The heterotrimeric influenza polymerase (FluPol), comprising PA, PB1, and PB2 subunits, is essential for viral replication and harbors virus-specific protein-protein interfaces that are potential drug targets. We focused on the highly conserved PA-PB1 interface, where the N-terminal peptide of PB1 binds the PA C-terminal domain with high affinity. Disrupting this interaction abrogates polymerase function, halting viral replication. Using phage display, we identified PB1-derived peptides with enhanced affinity for PA and characterized their binding via biophysical methods and X-ray crystallography. Lead peptides efficiently disrupted the PB1-PA interaction and inhibited polymerase activity in cell-based assays. To address peptide delivery challenges, we expressed these inhibitors intracellularly from synthetic mRNA formulated in lipid nanoparticles, achieving robust inhibition of viral replication in cultured cells. This work establishes intracellularly expressed peptide inhibitors as a viable antiviral strategy and provides a generalizable framework for targeting essential protein-protein interactions of influenza and other RNA viruses.

microbiology↗

bioRxiv2025

Revisiting the need for mRNA nucleoside modification in CAR T cell engineering

mRNA-based chimeric antigen receptor (CAR)-T cells offer the promise of enhanced safety and simplified manufacturing. However, in vitro-transcribed (IVT) mRNA is known to trigger antiviral immune responses, inflammatory signaling, and apoptosis in transfected cells. To address these challenges and enable efficient IVT-mRNA expression, modified nucleosides, such as N1-methyl-pseudouridine (m1{Psi}), have become the gold standard for CAR-T cell production, albeit at increased cost. In this study, immune responses to IVT-mRNA were evaluated across five primary human cell types, including T-cells. Unexpectedly, T-cells, unlike other immune and non-immune cell types tested, exhibited no immune activation in response to unmodified mRNA. T-cell viability and cytokine secretion patterns remained unaffected, regardless of whether unmodified mRNA was delivered via lipid nanoparticles (LNPs) or electroporation. Furthermore, CAR expression levels in T-cells were not influenced by mRNA modification with m1{Psi} or 5-methoxy-uridine (5moU) nucleosides. The absence of nucleoside modifications did not compromise CAR-T cell cytotoxic potency, demonstrating that such modifications are not required for producing functional CAR-T cells. These findings eliminate the need for nucleoside modification in T-cell mRNA, simplifying and reducing the cost of CAR-T cell manufacturing while positioning IVT-mRNA as a highly efficient and minimally invasive tool for CAR-T cell engineering.

bioengineering↗

bioRxiv2019

mRNA with mammalian codon bias accumulates in yeast mutants with constitutive stress granules

Stress granules and P bodies are cytoplasmic structures assembled in response to various stress factors and represent sites of temporary storage or decay of mRNAs. Depending on the source of stress, the formation of these structures may be driven by distinct mechanisms, but several stresses were shown to stabilize mRNAs via inhibition of deadenylation. A recent study identified yeast gene deletion mutants with constitutive stress granules and elevated P bodies; however, the mechanisms which trigger its formation remain poorly understood. Here, we investigate the possibility of accumulating mRNA with mammalian codon bias, which we termed the model RNA, in these mutants. We found that the model RNA accumulates in dcp2 and xrn1 mutants and in four mutants with constitutive stress granules overlapping with P bodies. However, in eight other mutants with constitutive stress granules the model RNA is downregulated, or its steady state levels vary. We further suggest that the accumulation of the model RNA is linked to its protection from the main mRNA surveillance path. However, there is no obvious targeting of the model RNA to stress granules or P bodies. Thus, accumulation of the model RNA and formation of constitutive stress granules occur independently and only some paths inducing formation of constitutive stress granules will stabilize mRNA as well.

molecular biology↗