Extracellular matrix sensing via modulation of orientational order of integrins and F-actin in focal adhesions

Mechanotransduction in Development: A Focus on Angiogenesis

Cells respond to external mechanical cues and transduce these forces into biological signals. This process is known as mechanotransduction and requires a group of proteins called mechanosensors. This peculiar class of receptors include extracellular matrix proteins, plasma membrane proteins, the cytoskeleton and the nuclear envelope. These cell components are responsive to a wide spectrum of physical cues including stiffness, tensile force, hydrostatic pressure and shear stress. Among mechanotransducers, the Transient Receptor Potential (TRP) and the PIEZO family members are mechanosensitive ion channels, coupling force transduction with intracellular cation transport. Their activity contributes to embryo development, tissue remodeling and repair, and cell homeostasis. In particular, vessel development is driven by hemodynamic cues such as flow direction and shear stress. Perturbed mechanotransduction is involved in several pathological vascular phenotypes including hereditary hemorrhagic telangiectasia. This review is conceived to summarize the most recent findings of mechanotransduction in development. We first collected main features of mechanosensitive proteins. However, we focused on the role of mechanical cues during development. Mechanosensitive ion channels and their function in vascular development are also discussed, with a focus on brain vessel morphogenesis.

Extracellular matrix stiffness modulates the mechanophenotypes and focal adhesions of colon cancer cells leading to their invasions via YAP1

Distal metastasis is the main cause of clinical treatment failure in patients with colon cancer. It is now known that the invasion and metastasis of cancer cells is precisely regulated by chemical and physical factors in vivo. However, the role of extracellular matrix (ECM) stiffness in colon cancer cell (CCCs) invasion and metastasis remains unclear. Here, bioinformatical analysis suggested that a high expression level of yes associated protein 1 (YAP1) was significantly associated with metastasis and poor prognosis in colon cancer patients. We further investigated the effects of polyacrylamide hydrogels with different stiffnesses (3, 20, and 38 ​kPa), which were simulated as ECM, on the mechanophenotype (F-actin cytoskeleton organization, electrophoretic rate, membrane fluidity, and Young's modulus) of CCCs. The results showed that a stiffer ECM could induce the maturation of focal adhesions and formation of stress fibers in CCCs, regulate their mechanophenotypes, and promote cell motility. We also demonstrated that the expression levels of YAP1 and paxillin were positively correlated in patients with colon cancer. YAP1 knockdown reduces paxillin clustering and cell motility and alters the cellular mechanophenotypes of CCCs. This is of great significance for an in-depth understanding of the invasion and metastatic mechanisms of colon cancer and for the optimization of clinical therapy from the perspective of mechanobiology.

Novel tools to study cell-ECM interactions, cell adhesion dynamics and migration

Integrin-mediated cell adhesion is essential for cell migration, mechanotransduction and tissue integrity. In vivo, these processes are regulated by complex physicochemical signals from the extracellular matrix (ECM). These nuanced cues, including molecular composition, rigidity and topology, call for sophisticated systems to faithfully explore cell behaviour. Here, we discuss recent methodological advances in cell-ECM adhesion research and compile a toolbox of techniques that we expect to shape this field in future. We outline methodological breakthroughs facilitating the transition from rigid 2D substrates to more complex and dynamic 3D systems, as well as advances in super-resolution imaging for an in-depth understanding of adhesion nanostructure. Selected methods are exemplified with relevant biological findings to underscore their applicability in cell adhesion research. We expect this new "toolbox" of methods will allow for a closer approximation of in vitro experimental setups to in vivo conditions, providing deeper insights into physiological and pathophysiological processes associated with cell-ECM adhesion.