PIEZO-dependent mechanosensing is essential for intestinal stem cell fate decision and maintenance.

Stem cells perceive and respond to biochemical and physical signals to maintain homeostasis. Yet, it remains unclear how stem cells sense mechanical signals from their niche in vivo. In this work, we investigated the roles of PIEZO mechanosensitive channels in the intestinal stem cell (ISC) niche.

A YAP-centered mechanotransduction loop drives collective breast cancer cell invasion.

Dense and aligned Collagen I fibers are associated with collective cancer invasion led by protrusive tumor cells, leader cells. In some breast tumors, a population of cancer cells (basal-like cells) maintain several epithelial characteristics and express the myoepithelial/basal cell marker Keratin 14 (K14). Emergence of leader cells and K14 expression are regarded as interconnected events triggered by Collagen I, however the underlying mechanisms remain unknown.

Cell division-dependent dissemination following E-cadherin loss underlies initiation of diffuse-type gastric cancer.

Loss of the cell-cell adhesion protein E-cadherin underlies the development of diffuse-type gastric cancer (DGC), which is characterized by the gradual accumulation of tumor cells originating from the gastric epithelium in the surrounding stroma. How E-cadherin deficiency drives DGC formation remains elusive. Therefore, we investigated the consequences of E-cadherin loss on gastric epithelial organization utilizing a human gastric organoid model and histological analyses of early-stage DGC lesions.

Co-cultures of colon cancer cells and cancer-associated fibroblasts recapitulate the aggressive features of mesenchymal-like colon cancer.

Background: Poor prognosis in colon cancer is associated with a high content of cancer-associated fibroblasts (CAFs) and an immunosuppressive tumor microenvironment. The relationship between these two features is incompletely understood. Here, we aimed to generate a model system for studying the interaction between cancer cells and CAFs and their effect on immune-related cytokines and T cell proliferation.

A mechanical G2 checkpoint controls epithelial cell division through E-cadherin-mediated regulation of Wee1-Cdk1.

Epithelial cell divisions are coordinated with cell loss to preserve epithelial integrity. However, how epithelia adapt their rate of cell division to changes in cell number, for instance during homeostatic turnover or wounding, is not well understood. Here, we show that epithelial cells sense local cell density through mechanosensitive E-cadherin adhesions to control G2/M cell-cycle progression.

Mechanical forces directing intestinal form and function.

The vertebrate intestine experiences a range of intrinsically generated and external forces during both development and adult homeostasis. It is increasingly understood how the coordination of these forces shapes the intestine through organ-scale folding and epithelial organization into crypt-villus compartments. Moreover, accumulating evidence shows that several cell types in the adult intestine can sense and respond to forces to regulate key cellular processes underlying adult intestinal functions and self-renewal.

Liver Colonization by Colorectal Cancer Metastases Requires YAP-Controlled Plasticity at the Micrometastatic Stage.

Unlabelled: Micrometastases of colorectal cancer can remain dormant for years prior to the formation of actively growing, clinically detectable lesions (i.e., colonization).

Diffuse gastric cancer: Emerging mechanisms of tumor initiation and progression.

Gastric cancer is globally the fourth leading cause of cancer-related deaths. Patients with diffuse-type gastric cancer (DGC) particularly have a poor prognosis that only marginally improved over the last decades, as conventional chemotherapies are frequently ineffective and specific therapies are unavailable. Early-stage DGC is characterized by intramucosal lesions of discohesive cells, which can be present for many years before the emergence of advanced DGC consisting of highly proliferative and invasive cells.

Inside-out regulation of E-cadherin conformation and adhesion.

Cadherin cell-cell adhesion proteins play key roles in tissue morphogenesis and wound healing. Cadherin ectodomains bind in two conformations, X-dimers and strand-swap dimers, with different adhesive properties. However, the mechanisms by which cells regulate ectodomain conformation are unknown.

Decoding mechanical cues by molecular mechanotransduction.

Cells are exposed to a variety of mechanical cues, including forces from their local environment and physical properties of the tissue. These mechanical cues regulate a vast number of cellular processes, relying on a repertoire of mechanosensors that transduce forces into biochemical pathways through mechanotransduction. Forces can act on different parts of the cell, carry information regarding magnitude and direction, and have distinct temporal profiles.

DLC1 is a direct target of activated YAP/TAZ that drives collective migration and sprouting angiogenesis.

Endothelial YAP/TAZ (YAP is also known as YAP1, and TAZ as WWTR1) signaling is crucial for sprouting angiogenesis and vascular homeostasis. However, the underlying molecular mechanisms that explain how YAP/TAZ control the vasculature remain unclear. This study reveals that the focal adhesion protein deleted-in-liver-cancer 1 (DLC1) is a direct transcriptional target of the activated YAP/TAZ-TEAD complex.

Force transduction by cadherin adhesions in morphogenesis.

Mechanical forces drive the remodeling of tissues during morphogenesis. This relies on the transmission of forces between cells by cadherin-based adherens junctions, which couple the force-generating actomyosin cytoskeletons of neighboring cells. Moreover, components of cadherin adhesions adopt force-dependent conformations that induce changes in the composition of adherens junctions, enabling transduction of mechanical forces into an intracellular response.

Adhesion to the host cell surface is sufficient to mediate entry into epithelial cells.

The intestinal epithelium is the first physiological barrier breached by the Gram-positive facultative pathogen during an in vivo infection. binds to the epithelial host cell receptor E-cadherin, which mediates a physical link between the bacterium and filamentous actin (F-actin). However, the importance of anchoring the bacterium to F-actin through E-cadherin for bacterial invasion has not been tested directly in epithelial cells.

E-cadherin and LGN align epithelial cell divisions with tissue tension independently of cell shape.

Tissue morphogenesis requires the coordinated regulation of cellular behavior, which includes the orientation of cell division that defines the position of daughter cells in the tissue. Cell division orientation is instructed by biochemical and mechanical signals from the local tissue environment, but how those signals control mitotic spindle orientation is not fully understood. Here, we tested how mechanical tension across an epithelial monolayer is sensed to orient cell divisions.

Cell division orientation is coupled to cell-cell adhesion by the E-cadherin/LGN complex.

Both cell-cell adhesion and oriented cell division play prominent roles in establishing tissue architecture, but it is unclear how they might be coordinated. Here, we demonstrate that the cell-cell adhesion protein E-cadherin functions as an instructive cue for cell division orientation. This is mediated by the evolutionarily conserved LGN/NuMA complex, which regulates cortical attachments of astral spindle microtubules.

Epithelial self-healing is recapitulated by a 3D biomimetic E-cadherin junction.

Epithelial monolayers undergo self-healing when wounded. During healing, cells collectively migrate into the wound site, and the converging tissue fronts collide and form a stable interface. To heal, migrating tissues must form cell-cell adhesions and reorganize from the front-rear polarity characteristic of cell migration to the apical-basal polarity of an epithelium.

Reevaluating αE-catenin monomer and homodimer functions by characterizing E-cadherin/αE-catenin chimeras.

As part of the E-cadherin-β-catenin-αE-catenin complex (CCC), mammalian αE-catenin binds F-actin weakly in the absence of force, whereas cytosolic αE-catenin forms a homodimer that interacts more strongly with F-actin. It has been concluded that cytosolic αE-catenin homodimer is not important for intercellular adhesion because E-cadherin/αE-catenin chimeras thought to mimic the CCC are sufficient to induce cell-cell adhesion. We show that, unlike αE-catenin in the CCC, these chimeras homodimerize, bind F-actin strongly, and inhibit the Arp2/3 complex, all of which are properties of the αE-catenin homodimer.

Rap2A links intestinal cell polarity to brush border formation.

The microvillus brush border at the apex of the highly polarized enterocyte allows the regulated uptake of nutrients from the intestinal lumen. Here, we identify the small G protein Rap2A as a molecular link that couples the formation of microvilli directly to the preceding cell polarization. Establishment of apicobasal polarity, which can be triggered by the kinase LKB1 in single, isolated colon cells, results in enrichment of PtdIns(4,5)P(2) at the apical membrane.

cAMP regulates DEP domain-mediated binding of the guanine nucleotide exchange factor Epac1 to phosphatidic acid at the plasma membrane.

Epac1 is a cAMP-regulated guanine nucleotide exchange factor for the small G protein Rap. Upon cAMP binding, Epac1 undergoes a conformational change that results in its release from autoinhibition. In addition, cAMP induces the translocation of Epac1 from the cytosol to the plasma membrane.

Regulating Rap small G-proteins in time and space.

Signaling by the small G-protein Rap is under tight regulation by its GEFs and GAPs. These are multi-domain proteins that are themselves controlled by distinct upstream pathways, and thus couple different extra- and intracellular cues to Rap. The individual RapGEFs and RapGAPs are, in addition, targeted to specific cellular locations by numerous anchoring mechanisms and, consequently, may control different pools of Rap.

The nucleoporin RanBP2 tethers the cAMP effector Epac1 and inhibits its catalytic activity.

Cyclic adenosine monophosphate (cAMP) is a second messenger that relays a wide range of hormone responses. In this paper, we demonstrate that the nuclear pore component RanBP2 acts as a negative regulator of cAMP signaling through Epac1, a cAMP-regulated guanine nucleotide exchange factor for Rap. We show that Epac1 directly interacts with the zinc fingers (ZNFs) of RanBP2, tethering Epac1 to the nuclear pore complex (NPC).

Ezrin is required for efficient Rap1-induced cell spreading.

The Rap family of small GTPases regulate the adhesion of cells to extracellular matrices. Several Rap-binding proteins have been shown to function as effectors that mediate Rap-induced adhesion. However, little is known regarding the relationships between these effectors, or about other proteins that are downstream of or act in parallel to the effectors.

Spatial regulation of cyclic AMP-Epac1 signaling in cell adhesion by ERM proteins.

Epac1 is a guanine nucleotide exchange factor for the small G protein Rap and is involved in membrane-localized processes such as integrin-mediated cell adhesion and cell-cell junction formation. Cyclic AMP (cAMP) directly activates Epac1 by release of autoinhibition and in addition induces its translocation to the plasma membrane. Here, we show an additional mechanism of Epac1 recruitment, mediated by activated ezrin-radixin-moesin (ERM) proteins.

Epac: defining a new mechanism for cAMP action.

cAMP is a second messenger that is essential for relaying hormonal responses in many biological processes. The discovery of the cAMP target Epac explained various effects of cAMP that could not be attributed to the established targets PKA and cyclic nucleotide-gated ion channels. Epac1 and Epac2 function as guanine nucleotide exchange factors for the small G protein Rap.