Biology subjects

Brosseau, J.-P.

Publications and source records attributed to Brosseau, J.-P..

4 recordsLinked to original sources

bioRxiv2025

Splicing Isoforms Associated to TGFb-Induced Myofibroblast Activation

Myofibroblast differentiation is a key process in developmental biology and involved in numerous physiopathology. The gene expression program orchestrating fibroblast to myofibroblast differentiation, as well as its recapitulation by TGF{beta} stimulation in vitro, is relatively well characterized. Intriguingly, it is known that the splicing isoform EDA+FN1 is a marker and driver of myofibroblast differentiation, but the alternative splicing landscape of myofibroblast is unknown. Here, we performed a high-throughput transcriptomic approach by RNA-Seq in a primary skin fibroblast line and uncover more than 250 splicing isoforms associated with TGF{beta}-induced myofibroblasts using two different bioinformatic pipelines. This splicing profile highlights a distinct layer of regulation when compared to the global gene expression profile of myofibroblasts. A 5 alternative splicing event (ASE) signature [ACTN1-19A/19B; COL5A1-64A/64B; COL6A3 exon 4; FLNA exon 30 and TPM1-6a/6b] was further validated by ddPCR and AS-PCR and retrieved in publicly available RNA-Seq datasets describing other TGF{beta}-stimulated lung and skin fibroblasts. Surprisingly, TGF{beta} does not induce an EDA+FN1 splicing shift, although it stimulates global fibronectin expression. Thus, we conclude that the 5 ASEs signature may be used as putative universal myofibroblast markers and be of functional significance to myofibroblast formation and biology.

genomics↗

bioRxiv2025

Proof-of-principle of NF1 Gene Therapy in plexiform neurofibroma mice models

Neurofibromatosis type I is a rare neurocutaneous syndrome characterized by the development of disfiguring neurofibroma tumors with unmet clinical needs. As Neurofibromatosis Type I is a monogenic disease, the development of gene therapy is highly attractive, but it is currently unknown if rescuing the NF1 gene in established neurofibroma is sufficient for tumor regression. Here, we test this hypothesis by building two novel NF1 mouse models with reversible NF1 expression. In the first model, the human NF1 -/- Schwann cells named ipNF95.11b were genetically modified with a doxycycline-inducible full-length mouse Nf1 gene. One month after cells implantation in the sciatic nerve, mice were split into 2 groups. Strikingly, all sciatic nerves from mice allowed to drink doxycycline water for one month display complete normalization of the sciatic nerve histologically (n=6 sciatic nerves) whereas 83% (5 out of 6 sciatic nerves) develop or maintain a neurofibroma when drinking regular water. In the second model, the human NF1 +/- Schwann cells named ipNF95.11c were genetically modified with a doxycycline-inducible potent shRNA against the NF1 mRNA transcript. Strikingly, doxycycline withdrawal after neurofibroma establishment allowed complete normalization (n=4 sciatic nerves), whereas all sciatic nerves showed evidence of neurofibroma when kept on doxycycline (n=4 sciatic nerves). Thus, we proof-of-principle NF1 Gene Therapy in plexiform neurofibroma mice models.

cancer biology↗

bioRxiv2022

The ITPRIPL1- CD3ϵ axis: a novel immune checkpoint controlling T cells activation

The immune system is critical to fighting infections and disease. The molecular recognition of harmful entities takes place when antigen-presenting cells (APC) harboring major histocompatibility complex (MHC) molecules bound to peptides derived from harmful antigens (ligand) dock on specific T cell receptor (TCR)-CD3 complex (receptor) at the surface of CD8+ T cells. The discovery of a general immune checkpoint mechanism to avoid the harmful impact of T cell hyperactivation provoked a paradigm shift. The clinical relevance of this mechanism is highlighted by the fact that PD-1 and PD-L1 inhibitors are very effective at boosting immune reactions. Still, immune evasion frequently happens. The observation that some PD-1/PD-L1 negative tumors have a poor immune response opens the door to identifying a novel immune checkpoint mechanism. Here, we discovered that ITPRIPL1, a gene with unknown function, impairs T cell activation. Surprisingly, we found that CD3{varepsilon} is the direct receptor of ITPRIPL1. This novel immune checkpoint was validated as a drug target using ITPRIPL1 KO mice and monoclonal antibodies. Thus, targeting the ITPRIPL1-CD3e axis, especially in PD-1 - PDL-1 negative patients, is a promising therapeutic strategy to reduce immune evasion.

immunology↗

bioRxiv2019

Palmitoylation is critically required for cancer intrinsic PD-1 expression and functions

Programmed cell death protein 1 (PD-1) is a crucial anticancer target, but the relatively low response rate and acquired resistance to existing antibody drugs highlight an urgent need to develop alternative targeting strategies. Here we report the palmitoylation of PD-1, discovered the main DHHC enzyme for this modification, revealed the mechanism for its effect on PD-1 expression, and rationally developed a peptide for targeting PD-1 expression. Palmitoylation promoted the trafficking of PD-1 to recycling endosome, thus preventing its lysosome-dependent degradation. Palmitoylation was required for the activation of PD-1 downstream signaling, and targeting palmitoylation by pharmacological inhibitor or depleting the modification enzyme caused significant anti-tumor effects. A peptide was designed to competitively inhibit PD-1 palmitoylation and expression, opening a new route for developing PD-1 inhibitors as a strategy for cancer immunotherapy.\n\nSignificanceWe show for the first time that PD-1 is palmitoylated, identify DHHC9 as the predominant enzyme for its palmitoylation, and reveal the molecular mechanisms underlying its effects on PD-1 stability and functions. Importantly, we also designed a competitive inhibitor targeting PD-1 palmitoylation, and this first-in-class molecule may inspire the development of new checkpoint inhibitors.

cancer biology↗