61 results found
Lachowski D, Matellan C, Cortes E, et al., 2021, Self-assembling polypeptide hydrogels as a platform to recapitulate the tumor microenvironment, Cancers, Vol: 13, Pages: 1-25, ISSN: 2072-6694
The tumor microenvironment plays a critical role in modulating cancer cell migration, metabolism, and malignancy, thus, highlighting the need to develop in vitro culture systems that can recapitulate its abnormal properties. While a variety of stiffness-tunable biomaterials, reviewed here, have been developed to mimic the rigidity of the tumor extracellular matrix, culture systems that can recapitulate the broader extracellular context of the tumor microenvironment (including pH and temperature) remain comparably unexplored, partially due to the difficulty in independently tuning these parameters. Here, we investigate a self-assembled polypeptide network hydrogel as a cell culture platform and demonstrate that the culture parameters, including the substrate stiffness, extracellular pH and temperature, can be independently controlled. We then use this biomaterial as a cell culture substrate to assess the effect of stiffness, pH and temperature on Suit2 cells, a pancreatic cancer cell line, and demonstrate that these microenvironmental factors can regulate two critical transcription factors in cancer: yes-associated protein 1 (YAP) and hypoxia inducible factor (HIF-1A).
Cheong SS, Akram K, Metellan C, et al., 2020, The planar polarity component Vangl2 is a key regulator of mechanosignaling, Frontiers in Cell and Developmental Biology, Vol: 8, ISSN: 2296-634X
VANGL2 is a component of the planar cell polarity (PCP) pathway, which regulates tissue polarity and patterning. The Vangl2Lp mutation causes lung branching defects due to dysfunctional actomyosin-driven morphogenesis. Since the actomyosin network regulates cell mechanics, we speculated that mechanosignaling could be impaired when VANGL2 is disrupted. Here, we used live-imaging of precision-cut lung slices (PCLS) from Vangl2Lp/+ mice to determine that alveologenesis is attenuated as a result of impaired epithelial cell migration. Vangl2Lp/+ tracheal epithelial cells (TECs) and alveolar epithelial cells (AECs) exhibited highly disrupted actomyosin networks and focal adhesions (FAs). Functional assessment of cellular forces confirmed impaired traction force generation in Vangl2Lp/+ TECs. YAP signaling in Vangl2Lp airway epithelium was reduced, consistent with a role for VANGL2 in mechanotransduction. Furthermore, activation of RhoA signaling restored actomyosin organization in Vangl2Lp/+, confirming RhoA as an effector of VANGL2. This study identifies a pivotal role for VANGL2 in mechanosignaling, which underlies the key role of the PCP pathway in tissue morphogenesis.
Lachowski D, Cortes Lopez J, Matellan C, et al., 2020, GPER regulates actin cytoskeleton dynamics to impair cell polarization, Frontiers in Cell and Developmental Biology, Vol: 8, ISSN: 2296-634X
Mechanical forces regulate cell functions through multiple pathways. G protein-coupled estrogen receptor (GPER) is a seven-transmembrane receptor that is ubiquitously expressed across tissues and mediates the acute cellular response to estrogens. Here, we demonstrate an unidentified role of GPER as a cellular mechanoregulator.G protein-coupled estrogen receptor signaling controls the assembly of stress fibers, the dynamics of the associated focal adhesions, and cell polarization via RhoA GTPase (RhoA). G protein-coupled estrogen receptor activation inhibits F-actin polymerization and subsequently triggers a negative feedback that transcriptionally suppresses the expression of monomeric G-actin. Given the broad expression of GPER and the range of cytoskeletal changes modulated by this receptor, our findings position GPER as a key player in mechanotransduction.
Lachowski D, Cortes Lopez J, Matellan C, et al., 2020, G protein-coupled estrogen receptor regulates actin cytoskeleton dynamics to impair cell polarization, Frontiers in Cell and Developmental Biology, Vol: 8, ISSN: 2296-634X
Mechanical forces regulate cell functions through multiple pathways. G protein-coupled estrogen receptor (GPER) is a seven-transmembrane receptor that is ubiquitously expressed across tissues and mediates the acute cellular response to estrogens. Here, we demonstrate an unidentified role of GPER as a cellular mechanoregulator. G protein-coupled estrogen receptor signaling controls the assembly of stress fibers, the dynamics of the associated focal adhesions, and cell polarization via RhoA GTPase (RhoA). G protein-coupled estrogen receptor activation inhibits F-actin polymerization and subsequently triggers a negative feedback that transcriptionally suppresses the expression of monomeric G-actin. Given the broad expression of GPER and the range of cytoskeletal changes modulated by this receptor, our findings position GPER as a key player in mechanotransduction.
Majkowska A, Redondo-Gomez C, Rice A, et al., 2020, Interfacial Self-Assembly to Spatially Organize Graphene Oxide Into Hierarchical and Bioactive Structures, FRONTIERS IN MATERIALS, Vol: 7, ISSN: 2296-8016
Chronopoulos A, Thorpe SD, Cortes E, et al., 2020, Syndecan-4 tunes cell mechanics by activating the kindlin-integrin-RhoA pathway, Nature Materials, Vol: 19, Pages: 669-678, ISSN: 1476-1122
Extensive research over the past decades has identified integrins to be the primary transmembrane receptors that enable cells to respond to external mechanical cues. We reveal here a mechanism whereby syndecan-4 tunes cell mechanics in response to localized tension via a coordinated mechanochemical signalling response that involves activation of two other receptors: epidermal growth factor receptor and β1 integrin. Tension on syndecan-4 induces cell-wide activation of the kindlin-2/β1 integrin/RhoA axis in a PI3K-dependent manner. Furthermore, syndecan-4-mediated tension at the cell–extracellular matrix interface is required for yes-associated protein activation. Extracellular tension on syndecan-4 triggers a conformational change in the cytoplasmic domain, the variable region of which is indispensable for the mechanical adaptation to force, facilitating the assembly of a syndecan-4/α-actinin/F-actin molecular scaffold at the bead adhesion. This mechanotransduction pathway for syndecan-4 should have immediate implications for the broader field of mechanobiology.
Mehta V, Pang K-L, Rozbesky D, et al., 2020, The guidance receptor plexin D1 is a mechanosensor in endothelial cells, NATURE, Vol: 578, Pages: 290-+, ISSN: 0028-0836
Rice A, Cortes Lopez JE, Lachowski D, et al., 2020, GPER activation inhibits cancer cell mechanotransduction and basement membrane invasion via RhoA, Cancers, Vol: 12, ISSN: 2072-6694
The invasive properties of cancer cells are intimately linked to their mechanical phenotype, which can be regulated by intracellular biochemical signalling. Cell contractility, induced by mechanotransduction of a stiff fibrotic matrix, and the epithelial–mesenchymal transition (EMT) promote invasion. Metastasis involves cells pushing through the basement membrane into the stroma—both of which are altered in composition with cancer progression. Agonists of the G protein-coupled oestrogen receptor (GPER), such as tamoxifen, have been largely used in the clinic, and interest in GPER, which is abundantly expressed in tissues, has greatly increased despite a lack of understanding regarding the mechanisms which promote its multiple effects. Here, we show that specific activation of GPER inhibits EMT, mechanotransduction and cell contractility in cancer cells via the GTPase Ras homolog family member A (RhoA). We further show that GPER activation inhibits invasion through an in vitro basement membrane mimic, similar in structure to the pancreatic basement membrane that we reveal as an asymmetric bilayer, which differs in composition between healthy and cancer patients.Keywords: cancer biomechanics; metastasis; G protein-coupled receptors; tumour microenvironment
Ghose R, Rice AJ, Cortes E, et al., 2020, Implementation of a basement membrane invasion assay using mesenteric tissue, CELL-DERIVED MATRICES, PT B, Editors: Caballero, Kundu, Reis, Publisher: ACADEMIC PRESS LTD-ELSEVIER SCIENCE LTD, Pages: 99-122
Mazza G, Telese A, Al-Akkad W, et al., 2019, Cirrhotic human liver extracellular matrix 3D scaffolds promote smad-dependent TGF-β1 epithelial mesenchymal transition, Cells, Vol: 9, Pages: 1-16, ISSN: 2073-4409
An altered liver microenvironment characterized by a dysregulated extracellular matrix (ECM) supports the development and progression of hepatocellular carcinoma (HCC). The development of experimental platforms able to reproduce these physio-pathological conditions is essential in order to identify and validate new therapeutic targets for HCC. The aim of this work was to validate a new in vitro model based on engineering three-dimensional (3D) healthy and cirrhotic human liver scaffolds with HCC cells recreating the micro-environmental features favoring HCC. Healthy and cirrhotic human livers ECM scaffolds were developed using a high shear stress oscillation-decellularization procedure. The scaffolds bio-physical/bio-chemical properties were analyzed by qualitative and quantitative approaches. Cirrhotic 3D scaffolds were characterized by biomechanical properties and microarchitecture typical of the native cirrhotic tissue. Proteomic analysis was employed on decellularized 3D scaffolds and showed specific enriched proteins in cirrhotic ECM in comparison to healthy ECM proteins. Cell repopulation of cirrhotic scaffolds highlighted a unique up-regulation in genes related to epithelial to mesenchymal transition (EMT) and TGFβ signaling. This was also supported by the presence and release of higher concentration of endogenous TGFβ1 in cirrhotic scaffolds in comparison to healthy scaffolds. Fibronectin secretion was significantly upregulated in cells grown in cirrhotic scaffolds in comparison to cells engrafted in healthy scaffolds. TGFβ1 induced the phosphorylation of canonical proteins Smad2/3, which was ECM scaffold-dependent. Important, TGFβ1-induced phosphorylation of Smad2/3 was significantly reduced and ECM scaffold-independent when pre/simultaneously treated with the TGFβ-R1 kinase inhibitor Galunisertib. In conclusion, the inherent features of cirrhotic human liver ECM micro-environment were dissected and characterized for the first time
Kwong Hong Tsang D, Lieberthal T, Watts C, et al., 2019, Chemically functionalised graphene FET biosensor for the label-free sensing of exosomes, Scientific Reports, Vol: 9, ISSN: 2045-2322
A graphene field-effect transistor (gFET) was non-covalently functionalised with 1-pyrenebutyric acid N-hydroxysuccinimide ester and conjugated with anti-CD63 antibodiesfor the label-free detection of exosomes.Using a microfluidic channel, part of a graphene film was exposed to solution. The change in electrical properties of the exposed graphene created anadditional minimum alongside the original Dirac point inthe drain-source current(Ids)-back-gate voltage (Vg) curve. When phosphate buffered saline (PBS) was present in the channel, the additional minimum was present at a Vglower than the original Dirac point and shifted with time when exosomes were introduced into the channel.Thisshift of the minimum from the PBS reference point reached saturationafter 30 minutesand was observed for multiple exosome concentrations. Upon conjugation with an isotype control, sensor responsetothe highest concentration ofexosomes was negligible in comparison to that with anti-CD63antibody, indicatingthat thefunctionalised gFETcan specifically detect exosomes at least down to 0.1μg/mLand is sensitive to concentration. Such a gFET biosensor has not been used before for exosome sensing and could be an effective tool for the liquid-biopsy detection of exosomes as biomarkers for early-stage identification of diseases such as cancer.
Rice A, Del Rio Hernandez A, 2019, The mutational landscape of pancreatic and liver cancer, as represented by circulating tumour DNA, Frontiers in Oncology, Vol: 9, ISSN: 2234-943X
The mutational landscapes of pancreatic and liver cancer share many common genetic alterations which drive cancer progression.However, these mutations do not occur in all cases of these diseases, and this tumoural heterogeneity impedes diagnosis,prognosis and therapeutic development. One minimally invasive method for the evaluation of tumour mutations is the analysis ofcirculating tumour DNA (ctDNA), released through apoptosis, necrosis and active secretion by tumour cells into various body fluids.By observing mutations in those genes which promote transformation by controlling the cell cycle and oncogenic signallingpathways, a representation of the mutational profile of the tumour is revealed. The analysis of ctDNA is a promising technique forinvestigating these two gastrointestinal cancers, as many studies have reported on the accuracy of ctDNA assessment fordiagnosis and prognosis using a variety of techniques.
Perone Y, Farrugia AJ, Rodriguez-Meira A, et al., 2019, SREBP1 drives keratin-80-dependent cytoskeletal changes and invasive behavior in endocrine-resistant ER alpha breast cancer (vol 10, 2115, 2019), NATURE COMMUNICATIONS, Vol: 10, ISSN: 2041-1723
Matellan C, Del Río Hernández AE, 2019, Where no hand has gone before: probing mechanobiology at the cellular level., ACS Biomaterials Science and Engineering, Vol: 5, Pages: 3703-3719, ISSN: 2373-9878
Physical forces and other mechanical stimuli are fundamental regulators of cell behavior and function. Cells are also biomechanically competent: they generate forces to migrate, contract, remodel, and sense their environment. As the knowledge of the mechanisms of mechanobiology increases, the need to resolve and probe increasingly small scales calls for novel technologies to mechanically manipulate cells, examine forces exerted by cells, and characterize cellular biomechanics. Here, we review novel methods to quantify cellular force generation, measure cell mechanical properties, and exert localized piconewton and nanonewton forces on cells, receptors, and proteins. The combination of these technologies will provide further insight on the effect of mechanical stimuli on cells and the mechanisms that convert these stimuli into biochemical and biomechanical activity.
Lachowski D, Cortes E, Rice A, et al., 2019, Matrix stiffness modulates the activity of MMP-9 and TIMP-1 in hepatic stellate cells to perpetuate fibrosis, Scientific Reports, Vol: 9, ISSN: 2045-2322
Liver fibrosis is characterised by a dense and highly cross-linked extracellular matrix (ECM) which promotes progression of diseases such as hepatocellular carcinoma. The fibrotic microenvironment is characterised by an increased stiffness, with rigidity associated with disease progression. External stiffness is known to promote hepatic stellate cell (HSC) activation through mechanotransduction, leading to increased secretion of ECM components. HSCs are key effector cells which maintain the composition of the ECM in health and disease, not only by regulating secretion of ECM proteins such as collagen, but also ECM-degrading enzymes called matrix metalloproteinases (MMPs) and their inhibitors (TIMPs). Uninhibited MMPs degrade ECM proteins to reduce external rigidity. Using fibronectin-coated polyacrylamide gels to alter substrate rigidity without altering ligand density, we show that fibrotic rigidities downregulate MMP-9 expression and secretion, and also upregulate secretion of TIMP-1, though not its expression. Using tissue immunofluorescence studies, we also report that the expression of MMP-9 is significantly decreased in activated HSCs in fibrotic tissues associated with hepatocellular carcinoma. This suggests the presence of a mechanical network that allows HSCs to maintain a fibrotic ECM, with external rigidity providing feedback which affects MMP-9 and TIMP-1 secretion, which may become dysregulated in fibrosis.
Perone Y, Farrugia AJ, Meira AR, et al., 2019, SREBP1 drives Keratin 80-dependent cytoskeletal changes and invasive behavior in endocrine resistant ERα breast cancer, Nature Communications, Vol: 10, ISSN: 2041-1723
Approximately 30% of ERα breast cancer patients relapse with metastatic disease following adjuvant endocrine therapies. The connection between acquisition of drug resistance and invasive potential is poorly understood. In this study, we demonstrate that the type II keratin topological associating domain undergoes epigenetic reprogramming in aromatase inhibitors (AI)-resistant cells, leading to Keratin-80 (KRT80) upregulation. KRT80 expression is driven by de novo enhancer activation by sterol regulatory element-binding protein 1 (SREBP1). KRT80 upregulation directly promotes cytoskeletal rearrangements at the leading edge, increased focal adhesion and cellular stiffening, collectively promoting cancer cell invasion. Shearwave elasticity imaging performed on prospectively recruited patients confirms KRT80 levels correlate with stiffer tumors. Immunohistochemistry showed increased KRT80-positive cells at relapse and, using several clinical endpoints, KRT80 expression associates with poor survival. Collectively, our data uncover an unpredicted and potentially targetable direct link between epigenetic and cytoskeletal reprogramming promoting cell invasion in response to chronic AI treatment.
Matellan C, Del Río Hernández AE, 2019, Engineering the cellular mechanical microenvironment - from bulk mechanics to the nanoscale., J Cell Sci, Vol: 132
The field of mechanobiology studies how mechanical properties of the extracellular matrix (ECM), such as stiffness, and other mechanical stimuli regulate cell behaviour. Recent advancements in the field and the development of novel biomaterials and nanofabrication techniques have enabled researchers to recapitulate the mechanical properties of the microenvironment with an increasing degree of complexity on more biologically relevant dimensions and time scales. In this Review, we discuss different strategies to engineer substrates that mimic the mechanical properties of the ECM and outline how these substrates have been applied to gain further insight into the biomechanical interaction between the cell and its microenvironment.
Cortes E, Lachowski D, Rice A, et al., 2019, Retinoic acid receptor-β is downregulated in hepatocellular carcinoma and cirrhosis and its expression inhibits myosin-driven activation and durotaxis in hepatic stellate cells, Hepatology, Vol: 69, Pages: 785-802, ISSN: 0270-9139
Hepatic stellate cells (HSCs) are essential perisinusoidal cells in the healthy and diseased liver. HSCs modulate extracellular matrix (ECM) homeostasis when quiescent, but in liver fibrosis, HSCs become activated and promote excess deposition of ECM molecules and tissue stiffening via force generation and mechanosensing. In hepatocellular carcinoma (HCC), activated HSCs infiltrate the stroma and migrate to the tumor core to facilitate paracrine signalling with cancer cells. Since the function of HSCs is known to be modulated by retinoids, we investigated the expression profile of retinoic acid receptor beta (RAR-β) in cirrhotic and HCC patients, as well as the effects of RAR-β activation in HSCs. We found that RAR-β expression is significantly reduced in cirrhotic and HCC tissues. Using a comprehensive set of biophysical methods combined with cellular and molecular biology, we have elucidated the biomechanical mechanism by which all trans-retinoic acid (ATRA) promotes HSC deactivation via RAR-β-dependent transcriptional downregulation of myosin light chain 2 (MLC-2) expression. Furthermore, this also abrogated mechanically driven migration towards stiffer substrates. CONCLUSION: Targeting mechanotransduction in HSCs at the transcriptional level may offer new therapeutic options for a range of liver diseases. This article is protected by copyright. All rights reserved.
Cortes E, Sarper M, Robinson B, et al., 2019, GPER is a mechanoregulator of pancreatic stellate cells and the tumor microenvironment, EMBO Reports, Vol: 20, ISSN: 1469-221X
The mechanical properties of the tumor microenvironment are emerging as attractive targets for the development of therapies. Tamoxifen, an agonist of the G protein-coupled estrogen receptor (GPER), is widely used to treat estrogen-positive breast cancer. Here, we show that tamoxifen mechanically reprograms the tumor microenvironment through a newly identified GPER-mediated mechanism. Tamoxifen inhibits the myofibroblastic differentiation of pancreatic stellate cells (PSCs) in the tumor microenvironment of pancreatic cancer in an acto-myosin-dependent manner via RhoA-mediated contractility, YAP deactivation, and GPER signaling. This hampers the ability of PSCs to remodel the extracellular matrix and to promote cancer cell invasion. Tamoxifen also reduces the recruitment and polarization to the M2 phenotype of tumor-associated macrophages. Our results highlight GPER as a mechanical regulator of the tumor microenvironment that targets the three hallmarks of pancreatic cancer: desmoplasia, inflammation, and immune suppression. The well-established safety of tamoxifen in clinics may offer the possibility to redirect the singular focus of tamoxifen on the cancer cells to the greater tumor microenvironment and lead a new strategy of drug repurposing.
Cortes E, Lachowski D, Robinson B, et al., 2019, Tamoxifen mechanically reprograms the tumor microenvironment via HIF-1A and reduces cancer cell survival, EMBO Reports, Vol: 20, ISSN: 1469-221X
The tumor microenvironment is fundamental to cancer progression, and the influence of its mechanical properties is increasingly being appreciated. Tamoxifen has been used for many years to treat estrogen-positive breast cancer. Here we report that tamoxifen regulates the level and activity of collagen cross-linking and degradative enzymes, and hence the organization of the extracellular matrix, via a mechanism involving both the G protein-coupled estrogen receptor (GPER) and hypoxia-inducible factor-1 alpha (HIF-1A). We show that tamoxifen reduces HIF-1A levels by suppressing myosin-dependent contractility and matrix stiffness mechanosensing. Tamoxifen also downregulates hypoxia-regulated genes and increases vascularization in PDAC tissues. Our findings implicate the GPER/HIF-1A axis as a master regulator of peri-tumoral stromal remodeling and the fibrovascular tumor microenvironment and offer a paradigm shift for tamoxifen from a well-established drug in breast cancer hormonal therapy to an alternative candidate for stromal targeting strategies in PDAC and possibly other cancers.
Rice A, Del Rio Hernandez A, 2019, Biomechanics of cancer cells, Bioengineering Innovative Solutions for Cancer, Pages: 327-361, ISBN: 9780128138878
The mechanical properties of cancer cells differ from that of healthy cells, and include changes in viscoelasticity, force generation, and mechanosensing, which are associated with invasive behaviors such as cell migration during metastasis. These attributes emerge from changes in the cytoskeleton and its dynamic behavior and composition. A multitude of analysis techniques are commonly used to assess these mechanical attributes and provide a wealth of information that is used to compare cancer cells with healthy cells or correlate mechanical properties with malignant properties such as invasiveness. Each technique is able to measure specific aspects of cell mechanics, and therefore when used in combination, provide a detailed understanding of the forces underlying cancer development and progression. This chapter details the wide range of techniques that have been used in the field of cancer cell mechanics and the conclusions that these studies have reached.
Cortes E, Lachowski D, Rice A, et al., 2018, Tamoxifen mechanically deactivates hepatic stellate cells via the G protein-coupled estrogen receptor, Oncogene, Vol: 38, Pages: 2910-2922, ISSN: 0950-9232
Tamoxifen has been used for many years to target estrogen receptor signalling in breast cancer cells. Tamoxifen is also an agonist of the G protein-coupled estrogen receptor (GPER), a GPCR ubiquitously expressed in tissues that mediates the acute response to estrogens. Here we report that tamoxifen promotes mechanical quiescence in hepatic stellate cells (HSCs), stromal fibroblast-like cells whose activation triggers and perpetuates liver fibrosis in hepatocellular carcinomas. This mechanical deactivation is mediated by the GPER/RhoA/myosin axis and induces YAP deactivation. We report that tamoxifen decreases the levels of hypoxia-inducible factor-1 alpha (HIF-1α) and the synthesis of extracellular matrix proteins through a mechanical mechanism that involves actomyosin-dependent contractility and mechanosensing of tissue stiffness. Our results implicate GPER-mediated estrogen signalling in the mechanosensory-driven activation of HSCs and put forward estrogenic signalling as an option for mechanical reprogramming of myofibroblast-like cells in the tumour microenvironment. Tamoxifen, with half a century of safe clinical use, might lead this strategy of drug repositioning.
Yeldag G, Rice A, Del Rio Hernandez A, 2018, Chemoresistance and the self-maintaining tumor microenvironment, Cancers, Vol: 10, ISSN: 2072-6694
The progression of cancer is associated with alterations in the tumor microenvironment, including changes in extracellular matrix (ECM) composition, matrix rigidity, hypervascularization, hypoxia, and paracrine factors. One key malignant phenotype of cancer cells is their ability to resist chemotherapeutics, and elements of the ECM can promote chemoresistance in cancer cells through a variety of signaling pathways, inducing changes in gene expression and protein activity that allow resistance. Furthermore, the ECM is maintained as an environment that facilitates chemoresistance, since its constitution modulates the phenotype of cancer-associated cells, which themselves affect the microenvironment. In this review, we discuss how the properties of the tumor microenvironment promote chemoresistance in cancer cells, and the interplay between these external stimuli. We focus on both the response of cancer cells to the external environment, as well as the maintenance of the external environment, and how a chemoresistant phenotype emerges from the complex signaling network present.
Samandari M, Julia MG, Rice A, et al., 2018, Liquid biopsies for management of pancreatic cancer, TRANSLATIONAL RESEARCH, Vol: 201, Pages: 98-127, ISSN: 1931-5244
Cameron W, Elijah M, Del Rio Hernandez A, 2018, Role of extracellular matrix in development and cancer progression, International Journal of Molecular Sciences, Vol: 19, ISSN: 1422-0067
The immense diversity of extracellular matrix (ECM) proteins confers distinct biochemical and biophysical properties that influence cell phenotype. The ECM is highly dynamic as it is constantly deposited, remodelled, and degraded during development until maturity to maintain tissue homeostasis. The ECM’s composition and organization are spatiotemporally regulated to control cell behaviour and differentiation, but dysregulation of ECM dynamics leads to the development of diseases such as cancer. The chemical cues presented by the ECM have been appreciated as key drivers for both development and cancer progression. However, the mechanical forces present due to the ECM have been largely ignored but recently recognized to play critical roles in disease progression and malignant cell behaviour. Here, we review the ways in which biophysical forces of the microenvironment influence biochemical regulation and cell phenotype during key stages of human development and cancer progression.
Haining AWM, Rahikainen R, Cortes E, et al., 2018, Mechanotransduction in talin through the interaction of the R8 domain with DLC1, PLoS Biology, Vol: 16, Pages: 1-20, ISSN: 1544-9173
The mechanical unfolding of proteins is a cellular mechanism for force transduction with potentially broad implications in cell fate. Despite this, the mechanism by which protein unfolding elicits differential downstream signalling pathways remains poorly understood. Here, we used protein engineering, atomic force microscopy, and biophysical tools to delineate how protein unfolding controls cell mechanics. Deleted in liver cancer 1 (DLC1) is a negative regulator of Ras homolog family member A (RhoA) and cell contractility that regulates cell behaviour when localised to focal adhesions bound to folded talin. Using a talin mutant resistant to force-induced unfolding of R8 domain, we show that talin unfolding determines DLC1 downstream signalling and, consequently, cell mechanics. We propose that this new mechanism of mechanotransduction may have implications for a wide variety of associated cellular processes.
Elsharkawy S, Al-Jawad M, Pantano MF, et al., 2018, Protein disorder-order interplay to guide the growth of hierarchical mineralized structures, Nature Communications, Vol: 9, ISSN: 2041-1723
Del Rio Hernandez AE, Matellan C, 2018, Cost-effective rapid prototyping and assembly of poly(methyl methacrylate)microfluidic devices., Scientific Reports, Vol: 8, ISSN: 2045-2322
The difficulty in translating conventional microfluidics from laboratory prototypes to commercial products has shifted research efforts towards thermoplastic materials for their higher translational potential and amenability to industrial manufacturing. Here, we present an accessible method to fabricate and assemble polymethyl methacrylate (PMMA) microfluidic devices in a “mask-less” and cost-effective manner that can be applied to manufacture a wide range of designs due to its versatility. Laser micromachining offers high flexibility in channel dimensions and morphology by controlling the laser properties, while our two-step surface treatment based on exposure to acetone vapour and low-temperature annealing enables improvement of the surface quality without deformation of the device. Finally, we demonstrate a capillarity-driven adhesive delivery bonding method that can produce an effective seal between PMMA devices and a variety of substrates, including glass, silicon and LiNbO3. We illustrate the potential of this technique with two microfluidic devices, an H-filter and a droplet generator. The technique proposed here offers a low entry barrier for the rapid prototyping of thermoplastic microfluidics, enabling iterative design for laboratories without access to conventional microfabrication equipment.
Mykuliak V, Haining A, von Essen M, et al., 2018, Mechanical unfolding reveals stable 3-helix intermediates in talin and α-catenin, PLoS Computational Biology, Vol: 14, ISSN: 1553-734X
Mechanical stability is a key feature in the regulation of structural scaffolding proteins and their functions. Despite the abundance of α-helical structures among the human proteome and their undisputed importance in health and disease, the fundamental principles of their behavior under mechanical load are poorly understood. Talin and α-catenin are two key molecules in focal adhesions and adherens junctions, respectively. In this study, we used a combination of atomistic steered molecular dynamics (SMD) simulations, polyprotein engineering, and single-molecule atomic force microscopy (smAFM) to investigate unfolding of these proteins. SMD simulations revealed that talin rod α-helix bundles as well as α-catenin α-helix domains unfold through stable 3-helix intermediates. While the 5-helix bundles were found to be mechanically stable, a second stable conformation corresponding to the 3-helix state was revealed. Mechanically weaker 4-helix bundles easily unfolded into a stable 3-helix conformation. The results of smAFM experiments were in agreement with the findings of the computational simulations. The disulfide clamp mutants, designed to protect the stable state, support the 3-helix intermediate model in both experimental and computational setups. As a result, multiple discrete unfolding intermediate states in the talin and α-catenin unfolding pathway were discovered. Better understanding of the mechanical unfolding mechanism of α-helix proteins is a key step towards comprehensive models describing the mechanoregulation of proteins.
von Erlach T, Bertazzo S, Wozniak MA, et al., 2018, Cell-geometry-dependent changes in plasma membrane order direct stem cell signalling and fate, Nature Materials, Vol: 17, Pages: 237-242, ISSN: 1476-1122
Cell size and shape affect cellular processes such as cell survival, growth and differentiation1,2,3,4, thus establishing cell geometry as a fundamental regulator of cell physiology. The contributions of the cytoskeleton, specifically actomyosin tension, to these effects have been described, but the exact biophysical mechanisms that translate changes in cell geometry to changes in cell behaviour remain mostly unresolved. Using a variety of innovative materials techniques, we demonstrate that the nanostructure and lipid assembly within the cell plasma membrane are regulated by cell geometry in a ligand-independent manner. These biophysical changes trigger signalling events involving the serine/threonine kinase Akt/protein kinase B (PKB) that direct cell-geometry-dependent mesenchymal stem cell differentiation. Our study defines a central regulatory role by plasma membrane ordered lipid raft microdomains in modulating stem cell differentiation with potential translational applications.
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