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Roca, V.

Publications and source records attributed to Roca, V..

3 recordsLinked to original sources

Intratumoral Heterogeneity of Vimentin Modulates Nuclear Mechanotransduction, DNA Damage Response and Cancer Cell Survival

Vimentin, a major intermediate filament protein, is essential for maintaining cellular integrity and regulating cytoskeletal dynamics. Its upregulation is a hallmark of epithelial-to-mesenchymal transition (EMT), a process that enhances cancer cell migration, invasion, and metastatic potential. However, single-cell transcriptomic analyses of glioblastoma, the most common and aggressive primary brain tumor, reveal that vimentin expression exhibits significant intratumoral heterogeneity, reflecting diverse cellular subpopulations that may contribute to tumor plasticity, therapy resistance, and disease progression. Here, we show that the absence of vimentin alters nuclear mechanotransduction in response to compression, leading to chromatin remodelling and profound changes in gene expression in cancer cells. Remarkably, we demonstrate that external compressive forces, akin to vimentin deficiency, disrupt DNA damage response pathways. This impairment compromises DNA damage sensing and repair, bypassing DNA damage checkpoints and apoptosis. Consequently, vimentin-negative tumor cells exhibit increased survival in response to physical stress and DNA damage, potentially driving radioresistance and further amplifying intratumoral heterogeneity.

cancer biology↗

Specific subcellular localization drives the different functions of CDC42 isoforms during migration

The small G-protein CDC42 is an evolutionary conserved polarity protein and a key regulator of numerous polarized cell functions, including directed cell migration. In vertebrates, alternative splicing gives rise to two CDC42 proteins: the ubiquitously expressed isoform (CDC42u) and the brain isoform (CDC42b), whose specific roles are not fully elucidated. The two isoforms only differ in their carboxy-terminal sequence, which includes the CAAX motif essential for CDC42 interaction with membrane. Here we show that these divergent sequences do not directly affect the range of CDC42s potential binding partners, but indirectly influence CDC42-driven signaling by controlling the specific subcellular localization of the two isoforms. In astrocytes and neural precursors, which naturally express both variants, CDC42u is mainly cytosolic and associates with the leading-edge plasma membrane of migrating cells where it recruits the Par6-PKC{zeta} complex to fulfill its polarity function. In contrast, CDC42b mainly localizes to intracellular membrane compartments, where it interacts with N-WASP. CDC42b does not participate in cell polarization but embodies the major isoform regulating endocytosis. Both CDC42 isoforms act in concert by contributing their specific functions to promote chemotaxis of neural precursors, demonstrating that the expression pattern of the two isoforms is decisive for the tissue-specific behavior of cells.

cell biology↗

Microtubules tune mechanosensitive cell responses

Mechanotransduction is a process by which cells sense the mechanical properties of their surrounding environment and adapt accordingly to perform cellular functions such as adhesion, migration and differentiation. Integrin-mediated focal adhesions are major sites of mechanotransduction and their connection with the actomyosin network is crucial for mechanosensing as well as the generation and transmission of forces onto the substrate. Despite having emerged as major regulators of cell adhesion and migration, the contribution of microtubules to mechanotransduction still remains elusive. Here, we show that actomyosin-dependent mechanosensing of substrate rigidity controls microtubule acetylation, a tubulin post-translational modification, by promoting the recruitment of the alpha-tubulin acetyl transferase (TAT1) to focal adhesions. Microtubule acetylation, in turn, promotes GEF-H1 mediated RhoA activation, actomyosin contractility and traction forces. Our results reveal a fundamental crosstalk between microtubules and actin in mechanotransduction, which contributes to mechanosensitive cell adhesion and migration.

cell biology↗