Biology subjects

McGourty, K.

Publications and source records attributed to McGourty, K..

4 recordsLinked to original sources

bioRxiv2025

Therapeutic Blockade of Type 2 Cytokines and PD1 Unleashes Anti-Tumor Immunity Through Coordinated Reprogramming of Innate and Adaptive Immune Surveillance

BackgroundCheckpoint inhibitors improve survival in patients with several types of tumors. However, resistance to checkpoint inhibitors creates an opportunity for patients to benefit from novel immunotherapies. The type 2 cytokines IL-4, IL-13 and TSLP have been implicated in suppressing anti-tumor immune responses through T and myeloid cells. Our current study tested whether combined therapeutic blockade of IL-4, IL-13 and TSLP improved anti-tumor immunity alone and in combination with PD1 antagonism. MethodsWe used in vitro experiments with primary cells to identify cell types likely to participate in controlling tumors upon IL-4, IL-13, TSLP and PD1 blockade. Therapeutic blockade in the subcutaneous CT26 model tested in vivo tumor growth inhibition and associated immunological changes. Bioinformatic analysis of human tumor bulk RNA sequencing data probed for survival associations with IL-4/IL-13 and TSLP transcriptional responses. ResultsIn vitro, IL-4 suppressed T cell-mediated tumor growth inhibition and reduced monocyte-derived dendritic cell expression of proteins associated with anti-tumor immunity. In vivo, blocking IL-4, IL-13, TSLP and PD1 improved tumor growth inhibition by creating "hotter" tumors. This was associated with repolarization of CD4 and CD8 T cells and shifts in monocyte, conventional type 1 and type 2 (or monocyte-derived) dendritic cell programs. Transcriptional responses to IL-4/IL-13 and TSLP were associated with poor survival outcomes across patients with several types of cancers. ConclusionTherapeutic blockade of IL-4, IL-13 and TSLP may drive immunological tumor growth inhibition in subsets of cancer patients alone and in combination with checkpoint inhibitors. Improved tumor growth inhibition was likely driven through augmented cytotoxic T cell priming in secondary lymphoid organs and improved reactivation by repolarized monocytes and dendritic cells in tumors.

cancer biology↗

bioRxiv2025

ECM Signatures Reveal Quiescent Stem Cell Diversity in the Colonic Niche

Colonic stem cells have a key role in the continuous regeneration of a healthy intestinal epithelium. Despite considerable advances in single-cell omics technologies, the transcriptional heterogeneity of rare cell types such as colonic stem cells, as well as their functional states and niche-specific behaviors, remain poorly characterised. In this study, we leverage a meta-analysis of scRNA-seq and spatial transcriptomic datasets to comprehensively map the heterogeneity of colonic stem cells. We identify multiple, previously underappreciated stem cell states, including distinct quiescent subtypes marked by CDKN1A (P21), CDKN1B (P27), and CDKN1C (P57), proliferative populations defined by MKI67 (Ki67) and LRIG1, and a lineage-committed intermediate subpopulation expressing MUC2. Strikingly, we find that these states can be robustly identified solely by their extracellular matrix (ECM) gene expression signatures, revealing ECM composition as a critical determinant of stem cell identity. Notably, LAMA1 expression is highly specific to the P57+ quiescent population, linking laminin-mediated microenvironments to the active maintenance of deep quiescence, consistent with our recent findings associating LAMA1 with quiescent cell survival. By applying these ECM gene signatures, we delineate discrete "micro-niches" of quiescent stem cells in healthy tissue and provide evidence that analogous states persist in the colorectal cancer (CRC) environment. Extending our approach to an unrelated tissue, the pancreas, we detect parallel quiescent cell subtypes, illustrating the broader applicability of ECM-based signatures. Taken together, our findings redefine the concept of stem cell heterogeneity in the colon, establish ECM-driven gene signatures as a powerful tool for characterizing stem cell states, and offer new perspectives on the niche-dependent regulation of both healthy and cancerous stem cell populations.

developmental biology↗

bioRxiv2024

Laminin 111 triggers cell quiescence and long-term survival by inducing IQGAP1-mediated cytosolic scaffolding of ERK and BAD inactivation

In an adult human body, only a minority ([~]1%) of cells are dividing; all others are either quiescent, senescent or terminally differentiated. Cellular quiescence, also called G0, is a reversible non-proliferative state in which cells, such as adult stem cells, exist until stimuli trigger their re-entry into the cell cycle. Quiescent cells are known to reside within microenvironment niches of specific extracellular matrix (ECM) composition, but the molecular mechanisms that control their entry and maintenance into G0 and their long-term survival are poorly understood. Here, using a reproducible and homogenous in vitro model of quiescence, ex vivo tissue histology, phosphoproteomics, and molecular cell biological assays, we revealed that Laminin 111 was sufficient to trigger i) reversible cell cycle exit into G0; ii) sustained and elevated MAPK/ERK signaling; and iii) long-term survival. We found that ERK was activated through the Rap1-BRAF-MEK arm underneath Laminin-binding Integrin 3{beta}1. Activated pERK was scaffolded into the cytoplasm by IQGAP1, thereby blocking its translocation into the nucleus and the activation of proliferative transcription factors. Instead, cytoplasmic pERK inhibited pro-apoptotic protein BAD, which mediated the survival of quiescent cells even in absence of mitogen stimuli. Importantly, we confirmed that pERK was elevated and retained in the cytoplasm of Lgr5+ stem cells when they were located within Laminin 1-positive niches in porcine intestine. These findings uncovered a molecular mechanism that may explain how quiescent cell pools, such as dormant adult stem cells, can survive many years despite low mitogen stimuli and be resistant to apoptotic challenges, including chemotherapy. HIGHLIGHTSO_LILaminin 111 is sufficient to induce cellular quiescence (G0) and long-term survival. C_LIO_LILaminin 111 triggers the sustained and elevated activation of ERK during G0. C_LIO_LIERK is activated not by growth factor receptors but through the Rap1-BRAF-MEK arm underneath Laminin-binding Integrin 3{beta}1. C_LIO_LIActive, phosphorylated ERK (pERK) is scaffolded by IQGAP1, which prevents it from translocating into the nucleus and activating proliferative transcription factors. C_LIO_LIInstead, cytoplasmic pERK mediates the phosphorylation, and thus inhibition, of BAD, thereby raising the threshold at which G0 cells enter apoptosis. C_LI

cell biology↗

bioRxiv2020

Cdk5 and GSK3β inhibit Fast Endophilin-Mediated Endocytosis

Endocytosis mediates the cellular uptake of micronutrients and cell surface proteins. Parallel to Clathrin-mediated endocytosis, additional Clathrin-independent endocytic routes exist, including fast Endophilin-mediated endocytosis (FEME). The latter is not constitutively active but requires the activation of selected receptors. In cell culture, however, the high levels of growth factors in the regular culture media induce spontaneous FEME, which can be suppressed upon serum starvation. Thus, we predicted a role for protein kinases in this growth factor receptor-mediated regulation of the pathway. Using chemical and genetic inhibition, we found that Cdk5 and GSK3{beta} are negative regulators of FEME. Their inhibition was sufficient to activate FEME promptly in resting cells and boosted the production of endocytic carriers containing {beta} 1-adrenergic receptor, following dobutamine addition. We established that the kinases suppress FEME at several levels. They control Dynamin-1 and Dynein recruitment and sorting of cargo receptors such as Plexin A1 and ROBO1 into FEME carriers. They do so by antagonizing the binding of Endophilin to Dynamin-1 as well as to Collapsin response mediator protein 4 (CRMP4), a Plexin A1 adaptor. Cdk5 and GSK3{beta} also hamper the binding and recruitment of Dynein onto FEME carriers by Bin1. Interestingly, we found that GSK3{beta} binds to Endophilin, thus imposing a local regulation of FEME. Collectively, these findings place the two kinases as key regulators of FEME, licensing cells for rapid uptake by the pathway only upon when Cdk5 and GSK3{beta} activity is low.

cell biology↗