Biology subjects

Brochu, S.

Publications and source records attributed to Brochu, S..

4 recordsLinked to original sources

bioRxiv2026

Redundant roles of YES and SRC tyrosine kinases in driving malignant peripheral nerve sheath tumors

Malignant peripheral nerve sheath tumors (MPNST) are highly aggressive soft tissue sarcomas that are largely incurable with no clinically effective systemic therapies or immunotherapies for advanced disease. Here, we identify the SRC-family kinases (SFKs) YES and SRC as redundant, essential drivers of MPNST growth. Dual inhibition of YES/SRC activity by genetic silencing or pharmacological SFK inhibitors markedly suppressed the proliferation of multiple NF1-mutant MPNST cell lines. In vivo, conditional genetic depletion of YES/SRC in MPNST cells abrogated tumor growth in subcutaneous and orthotopic models, and dasatinib treatment delayed tumor progression and improved overall survival. Integrated transcriptomic and phosphotyrosine proteomic analyses revealed that YES/SRC inactivation extensively rewires MPNST signaling, coordinately repressing multiple oncogenic signaling pathways and downstream cell cycle transcriptional programs. Unexpectedly, YES/SRC inhibition also upregulated interferon and antigen processing and presentation pathways and increased cell-surface MHC class I expression, consistent with tumor-intrinsic immune reactivation. Clinically, analysis of a large sarcoma cohort demonstrated that YES1 is significantly overexpressed in MPNST compared to benign soft tissue tumors. Collectively, our findings establish YES/SRC as non-oncogene vulnerabilities in MPNST.

cancer biology↗

bioRxiv2025

Transgenic Inducible MHC I Overexpression in Mouse Alveolar Type 2 Cells

The major histocompatibility complex class I (MHC I) is crucial in adaptive immunity, enabling CD8+ T cells to detect and eliminate infected and cancerous cells. Recent studies have uncovered significant variability in MHC I expression across tissues, challenging the traditional belief of uniform expression. Lung epithelial cells (LECs) express meager amounts of MHC I, which preserves the lung epithelium from excessive inflammation but renders it more susceptible to cancer and infection. Despite MHC I overexpression in various immunopathologies, its precise role in disease initiation or progression remains unclear due to the absence of suitable in vivo models for studying MHC I overexpression. This study introduces a novel mouse model with targeted surface MHC I upregulation. Leveraging a conditional Cre-lox system, we augmented Nlrc5 expression to specifically upregulate MHC I in alveolar type 2 (AT2) LECs, known for their low basal expression of MHC I and significant overexpression in disease. Our model demonstrated a rapid and sustained tenfold increase in MHC I surface expression persisting for up to a year without triggering pathology or inflammation. Comprehensive characterization and validation of this model indicated that MHC I overexpression does not serve as a primary initiator of respiratory diseases under steady-state conditions and shows a therapeutic window for increasing MHC I without significant damage to the lung epithelium. This adaptable model offers insights into the effects of tissue-specific MHC I regulation and presents new avenues for therapeutic development.

molecular biology↗

bioRxiv2024

Sex and Disease Regulate MHC I Expression in Human Lung Epithelial Cells

Major histocompatibility complex class I (MHC I) molecules present endogenous peptides to CD8+ T-cells for immunosurveillance of infections and cancers. Recent studies revealed unexpected heterogeneity in MHC I expression among cells of different lineages. While respiratory diseases rank among the leading causes of mortality, studies in mice showed that lung epithelial cells (LECs) express lower MHC I levels than all other tested cell types. The present study aimed to evaluate MHC I expression in human LECs from parenchymal explants using single-cell RNA sequencing (scRNA-seq) and immunostaining of primary human LECs. After confirming the low constitutive MHC I expression in human LECs, we observed a significant upregulation of MHC I across three chronic respiratory diseases: chronic obstructive pulmonary disease (COPD), idiopathic pulmonary fibrosis (IPF), and cystic fibrosis (CF). Additionally, we unveiled an unexpected sexual dimorphism in MHC I expression in both health and disease, with males exhibiting higher levels of MHC I under steady-state conditions. Gene expression analyses suggest that differential redox balance between sexes is instrumental in this dimorphism. Our study unveils the complex interplay between MHC I expression, sex, and respiratory diseases. Since, in other models, MHC I upregulation contributes to the development of immunopathologies, we propose that it might have a similar impact on chronic lung diseases. NEW & NOTEWORTHYThis study shows that MHC I expression is very low in healthy LECs but escalates significantly in three chronic respiratory diseases, potentially contributing to disease progression. Furthermore, sex-specific divergences in LEC MHC I levels hint at distinct susceptibilities to chronic lung inflammation between males and females. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=138 SRC="FIGDIR/small/599895v1_ufig1.gif" ALT="Figure 1"> View larger version (39K): org.highwire.dtl.DTLVardef@44cfaborg.highwire.dtl.DTLVardef@19e1e29org.highwire.dtl.DTLVardef@1ce179aorg.highwire.dtl.DTLVardef@16f8063_HPS_FORMAT_FIGEXP M_FIG C_FIG

immunology↗

bioRxiv2023

Transposable elements regulate thymus development and function

Transposable elements (TE) are repetitive sequences representing [~]45% of the human and mouse genomes and are highly expressed by medullary thymic epithelial cells (mTEC). In this study, we investigated the role of TEs on T-cell development in the thymus. We performed multi-omic analyses of TEs in human and mouse thymic cells to elucidate their role in T cell development. We report that TE expression in the human thymus is high and shows extensive age- and cell lineage-related variations. TE expression correlates with multiple transcription factors in all cell types of the human thymus. Two cell types express particularly broad TE repertoires: mTECs and plasmacytoid dendritic cells (pDC). In mTECs, transcriptomic data suggest that TEs interact with transcription factors essential for mTEC development and function (e.g., PAX1 and REL), and immunopeptidomic data showed that TEs generate MHC-I-associated peptides implicated in thymocyte education. Notably, AIRE, FEZF2, and CHD4 regulate small yet non-redundant sets of TEs in murine mTECs. Human thymic pDCs homogenously express large numbers of TEs that likely form dsRNA, which can activate innate immune receptors, potentially explaining why thymic pDCs constitutively secrete IFN LJ/{beta}. This study highlights the diversity of interactions between TEs and the adaptive immune system. TEs are genetic parasites, and the two thymic cell types most affected by TEs (mTEcs and pDCs) are essential to establishing central T-cell tolerance. Therefore, we propose that orchestrating TE expression in thymic cells is critical to prevent autoimmunity in vertebrates.

immunology↗