Biology subjects

Bordeleau, F.

Publications and source records attributed to Bordeleau, F..

3 recordsLinked to original sources

bioRxiv2026

Matrix Stiffness-driven FAK Splicing Tunes Cell Mechanosensing

The extracellular matrix (ECM) stiffness influences many physiological and pathological processes. Cells can sense mechanical changes within the ECM through mechanosensors, most notably through the focal adhesion kinase (FAK). Using human-derived data and 2D/3D engineered models, we identified a ubiquitous and uncharacterized FAK isoform lacking exon 4 (FAK{Delta}e4). We demonstrated that FAK{Delta}e4 splicing is regulated by substrate stiffness in a biphasic manner, in which an optimal stiffness is required for a maximal FAK{Delta}e4 expression. We further showed that FAK{Delta}e4 dictates at which stiffness optimal migration speed and invasion occur, impairs focal adhesion dynamics and maturation, and shifts its autophosphorylation and downstream YAP nuclear translocation toward lower stiffness compared to the canonical FAK isoform. Moreover, the FAK{Delta}e4 expression levels to canonical FAK determine at which stiffness cells will converge during durotaxis. Our results reveal how FAK{Delta}e4 acts as a fine-tuning mechanosensing switch and reframe our understanding of mechanotransduction.

cell biology↗

bioRxiv2024

ARHGEF17/TEM4 regulates the cell cycle through control of G1 progression

The Ras homolog (Rho) small GTPases, via their role in regulating the actin cytoskeleton, coordinate diverse cellular functions including cell morphology, adhesion and motility, as well as cell cycle progression, survival and apoptosis. The upstream Rho regulators for many of these functions are unknown. ARHGEF17 (also known as TEM4) is a Rho family guanine nucleotide exchange factor (GEF) that been implicated in cell migration, cell-cell junction formation and the mitotic checkpoint. In this study we characterize the regulation of the cell cycle by TEM4. We demonstrate that TEM4 depleted cells exhibit multiple defects in mitotic entry and duration, spindle morphology, and spindle orientation. In addition, we find that TEM4 insufficiency leads to excessive cortical actin polymerization and cell rounding defects. Mechanistically, we demonstrate that TEM4 depleted cells delay in G1 as a consequence of elevated levels of the G1/S inhibitor p21waf1/cip1 and that TEM4 depleted cells that progress through to mitosis, do so with decreased transcription of CCNB1 and thus attenuated levels of cyclin B. Importantly, cyclin B overexpression in TEM4-depleted cells largely rescues mitotic progression and chromosome segregation defects in anaphase. Our study thus illustrates the consequences of Rho signalling imbalance on cell cycle progression and identifies TEM4 as the first GEF governing Rho GTPase-mediated regulation of G1/S.

cell biology↗

bioRxiv2021

Weakly migratory metastatic breast cancer cells activate fibroblasts via microvesicle-Tg2 to facilitate dissemination and metastasis

Cancer cell migration is highly heterogeneous, and the migratory capability of cancer cells is thought to be an indicator of metastatic potential. It is becoming clear that a cancer cell does not have to be inherently migratory to metastasize, with weakly migratory cancer cells often found to be highly metastatic. However, the mechanism through which weakly migratory cells escape from the primary tumor remains unclear. Here, utilizing phenotypically sorted highly and weakly migratory breast cancer cells, we demonstrate that weakly migratory metastatic cells disseminate from the primary tumor via communication with stromal cells. While highly migratory cells are capable of single cell migration, weakly migratory cells rely on cell-cell signaling with fibroblasts to escape the primary tumor. Weakly migratory cells release microvesicles rich in tissue transglutaminase 2 (Tg2) which activate fibroblasts and lead weakly migratory cancer cell migration in vitro. These microvesicles also induce tumor stiffening and fibroblast activation in vivo and enhance the metastasis of weakly migratory cells. Our results identify microvesicles and Tg2 as potential therapeutic targets for metastasis and reveal a novel aspect of the metastatic cascade in which weakly migratory cells release microvesicles which activate fibroblasts to enhance cancer cell dissemination.

cancer biology↗