Adam Engler | University of California, San Diego (original) (raw)
Papers by Adam Engler
Cell stem cell, Jan 16, 2015
β-adrenergic signaling pathways mediate key aspects of cardiac function. Its dysregulation is ass... more β-adrenergic signaling pathways mediate key aspects of cardiac function. Its dysregulation is associated with a range of cardiac diseases, including dilated cardiomyopathy (DCM). Previously, we established an iPSC model of familial DCM from patients with a mutation in TNNT2, a sarcomeric protein. Here, we found that the β-adrenergic agonist isoproterenol induced mature β-adrenergic signaling in iPSC-derived cardiomyocytes (iPSC-CMs) but that this pathway was blunted in DCM iPSC-CMs. Although expression levels of several β-adrenergic signaling components were unaltered between control and DCM iPSC-CMs, we found that phosphodiesterases (PDEs) 2A and PDE3A were upregulated in DCM iPSC-CMs and that PDE2A was also upregulated in DCM patient tissue. We further discovered increased nuclear localization of mutant TNNT2 and epigenetic modifications of PDE genes in both DCM iPSC-CMs and patient tissue. Notably, pharmacologic inhibition of PDE2A and PDE3A restored cAMP levels and ameliorated t...
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Science translational medicine, Jan 17, 2015
The human heart is capable of functioning for decades despite minimal cell turnover or regenerati... more The human heart is capable of functioning for decades despite minimal cell turnover or regeneration, suggesting that molecular alterations help sustain heart function with age. However, identification of compensatory remodeling events in the aging heart remains elusive. We present the cardiac proteomes of young and old rhesus monkeys and rats, from which we show that certain age-associated remodeling events within the cardiomyocyte cytoskeleton are highly conserved and beneficial rather than deleterious. Targeted transcriptomic analysis in Drosophila confirmed conservation and implicated vinculin as a unique molecular regulator of cardiac function during aging. Cardiac-restricted vinculin overexpression reinforced the cortical cytoskeleton and enhanced myofilament organization, leading to improved contractility and hemodynamic stress tolerance in healthy and myosin-deficient fly hearts. Moreover, cardiac-specific vinculin overexpression increased median life span by more than 150% i...
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Nature cell biology, 2015
Matrix stiffness potently regulates cellular behaviour in various biological contexts. In breast ... more Matrix stiffness potently regulates cellular behaviour in various biological contexts. In breast tumours, the presence of dense clusters of collagen fibrils indicates increased matrix stiffness and correlates with poor survival. It is unclear how mechanical inputs are transduced into transcriptional outputs to drive tumour progression. Here we report that TWIST1 is an essential mechanomediator that promotes epithelial-mesenchymal transition (EMT) in response to increasing matrix stiffness. High matrix stiffness promotes nuclear translocation of TWIST1 by releasing TWIST1 from its cytoplasmic binding partner G3BP2. Loss of G3BP2 leads to constitutive TWIST1 nuclear localization and synergizes with increasing matrix stiffness to induce EMT and promote tumour invasion and metastasis. In human breast tumours, collagen fibre alignment, a marker of increasing matrix stiffness, and reduced expression of G3BP2 together predict poor survival. Our findings reveal a TWIST1-G3BP2 mechanotransdu...
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Biomaterials, 2015
Development of stem cell delivery system with ability of control over mutilineage differentiation... more Development of stem cell delivery system with ability of control over mutilineage differentiation and improved engraft efficiency is imperative in regenerative medicine. We herein report transfer stamping of human mesenchymal stem cells (hMSCs) patches using thermally expandable hydrogels with tunable cell-adhesive properties. The hydrogels were prepared from functionalized four arm copolymer of Tetronic(®), and the cell adhesion on the hydrogel was modulated by incorporation of fibronectin (FN) or cell-adhesive peptide (RGD). The resulting hydrogels showed spontaneous expansion in size within 10 min in response to the temperature reduction from 37 to 4°C. The adhesion and proliferation of hMSCs on FN-hydrogels were positively tunable in proportion to the amount of FN within hydrogels with complete monolayer of hMSCs (hMSC patch) being successfully achieved. The hMSC patch on the hydrogel was faced to the target substrate, which was then easily detached and re-attached to the target...
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Nature materials, 2014
Stem cells regulate their fate by binding to, and contracting against, the extracellular matrix. ... more Stem cells regulate their fate by binding to, and contracting against, the extracellular matrix. Recently, it has been proposed that in addition to matrix stiffness and ligand type, the degree of coupling of fibrous protein to the surface of the underlying substrate, that is, tethering and matrix porosity, also regulates stem cell differentiation. By modulating substrate porosity without altering stiffness in polyacrylamide gels, we show that varying substrate porosity did not significantly change protein tethering, substrate deformations, or the osteogenic and adipogenic differentiation of human adipose-derived stromal cells and marrow-derived mesenchymal stromal cells. Varying protein-substrate linker density up to 50-fold changed tethering, but did not affect osteogenesis, adipogenesis, surface-protein unfolding or underlying substrate deformations. Differentiation was also unaffected by the absence of protein tethering. Our findings imply that the stiffness of planar matrices re...
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Methods in cell biology, 2007
In conjunction with surface chemistry, the mechanical properties of cell culture substrates provi... more In conjunction with surface chemistry, the mechanical properties of cell culture substrates provide important biological cues that affect cell behavior including growth, differentiation, spreading, and migration. The phenomenon has led to the increased use of biological and synthetic polymer-based flexible substrates in cell culture studies. However, widely used methods for measuring the Young's modulus have proven difficult in the characterization of these materials, as they tend to be relatively thin, soft, hydrated, and tethered to glass substrates. Here we describe three methods that have been applied successfully to probe the flexibility of soft culture substrates.
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Cell patterning is typically accomplished by selectively depositing proteins for cell adhesion on... more Cell patterning is typically accomplished by selectively depositing proteins for cell adhesion only on patterned regions; however in tissues, cells are also influenced by mechanical stimuli, which can also result in patterned arrangements of cells. We developed a mechanically-patterned hydrogel to observe and compare it to extracellular matrix (ECM) ligand patterns to determine how to best regulate and improve cell type-specific behaviors. Ligand-based patterning on hydrogels was not robust over prolonged culture, but cells on mechanically-patterned hydrogels differentially sorted based on stiffness preference: myocytes and adipose-derived stem cells (ASCs) underwent stiffness-mediated migration, i.e. durotaxis, and remained on myogenic hydrogel regions. Myocytes developed aligned striations and fused on myogenic stripes of the mechanically-patterned hydrogel. ASCs aligned and underwent myogenesis, but their fusion rate increased, as did the number of cells fusing into a myotube as a result of their alignment. Conversely, neuronal cells did not exhibit durotaxis and could be seen on soft regions of the hydrogel for prolonged culture time. These results suggest that mechanically-patterned hydrogels could provide a platform to create tissue engineered, innervated micro-muscles of neural and muscle phenotypes juxtaposed next to each other in order better recreate a muscle niche.
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Progress in molecular biology and translational science, 2014
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Methods in Cell Biology, 2007
In conjunction with surface chemistry, the mechanical properties of cell culture substrates provi... more In conjunction with surface chemistry, the mechanical properties of cell culture substrates provide important biological cues that affect cell behavior including growth, differentiation, spreading, and migration. The phenomenon has led to the increased use of biological and synthetic polymer-based flexible substrates in cell culture studies. However, widely used methods for measuring the Young's modulus have proven difficult in the characterization of these materials, as they tend to be relatively thin, soft, hydrated, and tethered to glass substrates. Here we describe three methods that have been applied successfully to probe the flexibility of soft culture substrates.
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Scientific reports, 2014
Cells secrete and assemble extracellular matrix throughout development, giving rise to time-depen... more Cells secrete and assemble extracellular matrix throughout development, giving rise to time-dependent, tissue-specific stiffness. Mimicking myocardial matrix stiffening, i.e. ~10-fold increase over 1 week, with a hydrogel system enhances myofibrillar organization of embryonic cardiomyocytes compared to static hydrogels, and thus we sought to identify specific mechanosensitive proteins involved. Expression and/or phosphorylation state of 309 unique protein kinases were examined in embryonic cardiomyocytes plated on either dynamically stiffening or static mature myocardial stiffness hydrogels. Gene ontology analysis of these kinases identified cardiogenic pathways that exhibited time-dependent up-regulation on dynamic versus static matrices, including PI3K/AKT and p38 MAPK, while GSK3β, a known antagonist of cardiomyocyte maturation, was down-regulated. Additionally, inhibiting GSK3β on static matrices improved spontaneous contraction and myofibril organization, while inhibiting agoni...
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Orthopaedic Biomechanics, 2012
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PLoS ONE, 2014
Single-molecule experiments indicate that integrin affinity is cation-type-dependent, but in spre... more Single-molecule experiments indicate that integrin affinity is cation-type-dependent, but in spread cells integrins are engaged in complex focal adhesions (FAs), which can also regulate affinity. To better understand cation-type-dependent adhesion in fully spread cells, we investigated attachment strength by application of external shear. While cell attachment strength is indeed modulated by cations, the regulation of integrin-mediated adhesion is also exceedingly complex, cell specific, and niche dependent. In the presence of magnesium only, fibroblasts and fibrosarcoma cells remodel their cytoskeleton to align in the direction of applied shear in an α5-integrin/fibronectin-dependent manner, which allows them to withstand higher shear. In the presence of calcium or on collagen in modest shear, fibroblasts undergo piecewise detachment but fibrosarcoma cells exhibit increased attachment strength. These data augment the current understanding of force-mediated detachment by suggesting a dynamic interplay in situ between cell adhesion and integrins depending on local niche cation conditions.
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Methods in Cell Biology, 2007
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Nature Materials, 2014
The stem cell/material interface is a complex, dynamic microenvironment in which the cell and the... more The stem cell/material interface is a complex, dynamic microenvironment in which the cell and the material cooperatively dictate one another's fate: the cell by remodelling its surroundings, and the material through its inherent properties (such as adhesivity, stiffness, nanostructure or degradability). Stem cells in contact with materials are able to sense their properties, integrate cues via signal propagation and ultimately translate parallel signalling information into cell fate decisions. However, discovering the mechanisms by which stem cells respond to inherent material characteristics is challenging because of the highly complex, multicomponent signalling milieu present in the stem cell environment. In this Review, we discuss recent evidence that shows that inherent material properties may be engineered to dictate stem cell fate decisions, and overview a subset of the operative signal transduction mechanisms that have begun to emerge. Further developments in stem cell engineering and mechanotransduction are poised to have substantial implications for stem cell biology and regenerative medicine.
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ASME 2007 Summer Bioengineering Conference, 2007
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Cardiomyocytes derived from embryos beat spontaneously in culture, but it is shown here with a se... more Cardiomyocytes derived from embryos beat spontaneously in culture, but it is shown here with a series of flexible substrates that matrices which mimic the elasticity of the developing heart are optimal for 1-Hz beating, for transmitting contractile work to the matrix, and for promoting actomyosin striation. On hard matrices that mechanically mimic a post-infarct fibrotic scar, cells overstrain themselves, lack striated myofibrils and stop beating; on very soft matrices, cells preserve contractile beating for days in culture but do very little work. Optimal matrix leads to a strain match between cell and matrix, and suggests dynamic differences in intracellular protein structures. A novel `cysteine shotgun' method of labeling the in situ proteome reveals differences in assembly or conformation of several abundant cytoskeletal proteins, including vimentin, filamin and myosin.
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The Journal of Cell Biology, 2004
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Journal of Cell Science, 2008
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Cell, 2006
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Cell stem cell, Jan 16, 2015
β-adrenergic signaling pathways mediate key aspects of cardiac function. Its dysregulation is ass... more β-adrenergic signaling pathways mediate key aspects of cardiac function. Its dysregulation is associated with a range of cardiac diseases, including dilated cardiomyopathy (DCM). Previously, we established an iPSC model of familial DCM from patients with a mutation in TNNT2, a sarcomeric protein. Here, we found that the β-adrenergic agonist isoproterenol induced mature β-adrenergic signaling in iPSC-derived cardiomyocytes (iPSC-CMs) but that this pathway was blunted in DCM iPSC-CMs. Although expression levels of several β-adrenergic signaling components were unaltered between control and DCM iPSC-CMs, we found that phosphodiesterases (PDEs) 2A and PDE3A were upregulated in DCM iPSC-CMs and that PDE2A was also upregulated in DCM patient tissue. We further discovered increased nuclear localization of mutant TNNT2 and epigenetic modifications of PDE genes in both DCM iPSC-CMs and patient tissue. Notably, pharmacologic inhibition of PDE2A and PDE3A restored cAMP levels and ameliorated t...
Bookmarks Related papers MentionsView impact
Science translational medicine, Jan 17, 2015
The human heart is capable of functioning for decades despite minimal cell turnover or regenerati... more The human heart is capable of functioning for decades despite minimal cell turnover or regeneration, suggesting that molecular alterations help sustain heart function with age. However, identification of compensatory remodeling events in the aging heart remains elusive. We present the cardiac proteomes of young and old rhesus monkeys and rats, from which we show that certain age-associated remodeling events within the cardiomyocyte cytoskeleton are highly conserved and beneficial rather than deleterious. Targeted transcriptomic analysis in Drosophila confirmed conservation and implicated vinculin as a unique molecular regulator of cardiac function during aging. Cardiac-restricted vinculin overexpression reinforced the cortical cytoskeleton and enhanced myofilament organization, leading to improved contractility and hemodynamic stress tolerance in healthy and myosin-deficient fly hearts. Moreover, cardiac-specific vinculin overexpression increased median life span by more than 150% i...
Bookmarks Related papers MentionsView impact
Nature cell biology, 2015
Matrix stiffness potently regulates cellular behaviour in various biological contexts. In breast ... more Matrix stiffness potently regulates cellular behaviour in various biological contexts. In breast tumours, the presence of dense clusters of collagen fibrils indicates increased matrix stiffness and correlates with poor survival. It is unclear how mechanical inputs are transduced into transcriptional outputs to drive tumour progression. Here we report that TWIST1 is an essential mechanomediator that promotes epithelial-mesenchymal transition (EMT) in response to increasing matrix stiffness. High matrix stiffness promotes nuclear translocation of TWIST1 by releasing TWIST1 from its cytoplasmic binding partner G3BP2. Loss of G3BP2 leads to constitutive TWIST1 nuclear localization and synergizes with increasing matrix stiffness to induce EMT and promote tumour invasion and metastasis. In human breast tumours, collagen fibre alignment, a marker of increasing matrix stiffness, and reduced expression of G3BP2 together predict poor survival. Our findings reveal a TWIST1-G3BP2 mechanotransdu...
Bookmarks Related papers MentionsView impact
Biomaterials, 2015
Development of stem cell delivery system with ability of control over mutilineage differentiation... more Development of stem cell delivery system with ability of control over mutilineage differentiation and improved engraft efficiency is imperative in regenerative medicine. We herein report transfer stamping of human mesenchymal stem cells (hMSCs) patches using thermally expandable hydrogels with tunable cell-adhesive properties. The hydrogels were prepared from functionalized four arm copolymer of Tetronic(®), and the cell adhesion on the hydrogel was modulated by incorporation of fibronectin (FN) or cell-adhesive peptide (RGD). The resulting hydrogels showed spontaneous expansion in size within 10 min in response to the temperature reduction from 37 to 4°C. The adhesion and proliferation of hMSCs on FN-hydrogels were positively tunable in proportion to the amount of FN within hydrogels with complete monolayer of hMSCs (hMSC patch) being successfully achieved. The hMSC patch on the hydrogel was faced to the target substrate, which was then easily detached and re-attached to the target...
Bookmarks Related papers MentionsView impact
Nature materials, 2014
Stem cells regulate their fate by binding to, and contracting against, the extracellular matrix. ... more Stem cells regulate their fate by binding to, and contracting against, the extracellular matrix. Recently, it has been proposed that in addition to matrix stiffness and ligand type, the degree of coupling of fibrous protein to the surface of the underlying substrate, that is, tethering and matrix porosity, also regulates stem cell differentiation. By modulating substrate porosity without altering stiffness in polyacrylamide gels, we show that varying substrate porosity did not significantly change protein tethering, substrate deformations, or the osteogenic and adipogenic differentiation of human adipose-derived stromal cells and marrow-derived mesenchymal stromal cells. Varying protein-substrate linker density up to 50-fold changed tethering, but did not affect osteogenesis, adipogenesis, surface-protein unfolding or underlying substrate deformations. Differentiation was also unaffected by the absence of protein tethering. Our findings imply that the stiffness of planar matrices re...
Bookmarks Related papers MentionsView impact
Methods in cell biology, 2007
In conjunction with surface chemistry, the mechanical properties of cell culture substrates provi... more In conjunction with surface chemistry, the mechanical properties of cell culture substrates provide important biological cues that affect cell behavior including growth, differentiation, spreading, and migration. The phenomenon has led to the increased use of biological and synthetic polymer-based flexible substrates in cell culture studies. However, widely used methods for measuring the Young's modulus have proven difficult in the characterization of these materials, as they tend to be relatively thin, soft, hydrated, and tethered to glass substrates. Here we describe three methods that have been applied successfully to probe the flexibility of soft culture substrates.
Bookmarks Related papers MentionsView impact
Bookmarks Related papers MentionsView impact
Cell patterning is typically accomplished by selectively depositing proteins for cell adhesion on... more Cell patterning is typically accomplished by selectively depositing proteins for cell adhesion only on patterned regions; however in tissues, cells are also influenced by mechanical stimuli, which can also result in patterned arrangements of cells. We developed a mechanically-patterned hydrogel to observe and compare it to extracellular matrix (ECM) ligand patterns to determine how to best regulate and improve cell type-specific behaviors. Ligand-based patterning on hydrogels was not robust over prolonged culture, but cells on mechanically-patterned hydrogels differentially sorted based on stiffness preference: myocytes and adipose-derived stem cells (ASCs) underwent stiffness-mediated migration, i.e. durotaxis, and remained on myogenic hydrogel regions. Myocytes developed aligned striations and fused on myogenic stripes of the mechanically-patterned hydrogel. ASCs aligned and underwent myogenesis, but their fusion rate increased, as did the number of cells fusing into a myotube as a result of their alignment. Conversely, neuronal cells did not exhibit durotaxis and could be seen on soft regions of the hydrogel for prolonged culture time. These results suggest that mechanically-patterned hydrogels could provide a platform to create tissue engineered, innervated micro-muscles of neural and muscle phenotypes juxtaposed next to each other in order better recreate a muscle niche.
Bookmarks Related papers MentionsView impact
Progress in molecular biology and translational science, 2014
Bookmarks Related papers MentionsView impact
Methods in Cell Biology, 2007
In conjunction with surface chemistry, the mechanical properties of cell culture substrates provi... more In conjunction with surface chemistry, the mechanical properties of cell culture substrates provide important biological cues that affect cell behavior including growth, differentiation, spreading, and migration. The phenomenon has led to the increased use of biological and synthetic polymer-based flexible substrates in cell culture studies. However, widely used methods for measuring the Young's modulus have proven difficult in the characterization of these materials, as they tend to be relatively thin, soft, hydrated, and tethered to glass substrates. Here we describe three methods that have been applied successfully to probe the flexibility of soft culture substrates.
Bookmarks Related papers MentionsView impact
Scientific reports, 2014
Cells secrete and assemble extracellular matrix throughout development, giving rise to time-depen... more Cells secrete and assemble extracellular matrix throughout development, giving rise to time-dependent, tissue-specific stiffness. Mimicking myocardial matrix stiffening, i.e. ~10-fold increase over 1 week, with a hydrogel system enhances myofibrillar organization of embryonic cardiomyocytes compared to static hydrogels, and thus we sought to identify specific mechanosensitive proteins involved. Expression and/or phosphorylation state of 309 unique protein kinases were examined in embryonic cardiomyocytes plated on either dynamically stiffening or static mature myocardial stiffness hydrogels. Gene ontology analysis of these kinases identified cardiogenic pathways that exhibited time-dependent up-regulation on dynamic versus static matrices, including PI3K/AKT and p38 MAPK, while GSK3β, a known antagonist of cardiomyocyte maturation, was down-regulated. Additionally, inhibiting GSK3β on static matrices improved spontaneous contraction and myofibril organization, while inhibiting agoni...
Bookmarks Related papers MentionsView impact
Orthopaedic Biomechanics, 2012
Bookmarks Related papers MentionsView impact
PLoS ONE, 2014
Single-molecule experiments indicate that integrin affinity is cation-type-dependent, but in spre... more Single-molecule experiments indicate that integrin affinity is cation-type-dependent, but in spread cells integrins are engaged in complex focal adhesions (FAs), which can also regulate affinity. To better understand cation-type-dependent adhesion in fully spread cells, we investigated attachment strength by application of external shear. While cell attachment strength is indeed modulated by cations, the regulation of integrin-mediated adhesion is also exceedingly complex, cell specific, and niche dependent. In the presence of magnesium only, fibroblasts and fibrosarcoma cells remodel their cytoskeleton to align in the direction of applied shear in an α5-integrin/fibronectin-dependent manner, which allows them to withstand higher shear. In the presence of calcium or on collagen in modest shear, fibroblasts undergo piecewise detachment but fibrosarcoma cells exhibit increased attachment strength. These data augment the current understanding of force-mediated detachment by suggesting a dynamic interplay in situ between cell adhesion and integrins depending on local niche cation conditions.
Bookmarks Related papers MentionsView impact
Methods in Cell Biology, 2007
Bookmarks Related papers MentionsView impact
Nature Materials, 2014
The stem cell/material interface is a complex, dynamic microenvironment in which the cell and the... more The stem cell/material interface is a complex, dynamic microenvironment in which the cell and the material cooperatively dictate one another's fate: the cell by remodelling its surroundings, and the material through its inherent properties (such as adhesivity, stiffness, nanostructure or degradability). Stem cells in contact with materials are able to sense their properties, integrate cues via signal propagation and ultimately translate parallel signalling information into cell fate decisions. However, discovering the mechanisms by which stem cells respond to inherent material characteristics is challenging because of the highly complex, multicomponent signalling milieu present in the stem cell environment. In this Review, we discuss recent evidence that shows that inherent material properties may be engineered to dictate stem cell fate decisions, and overview a subset of the operative signal transduction mechanisms that have begun to emerge. Further developments in stem cell engineering and mechanotransduction are poised to have substantial implications for stem cell biology and regenerative medicine.
Bookmarks Related papers MentionsView impact
ASME 2007 Summer Bioengineering Conference, 2007
Bookmarks Related papers MentionsView impact
Cardiomyocytes derived from embryos beat spontaneously in culture, but it is shown here with a se... more Cardiomyocytes derived from embryos beat spontaneously in culture, but it is shown here with a series of flexible substrates that matrices which mimic the elasticity of the developing heart are optimal for 1-Hz beating, for transmitting contractile work to the matrix, and for promoting actomyosin striation. On hard matrices that mechanically mimic a post-infarct fibrotic scar, cells overstrain themselves, lack striated myofibrils and stop beating; on very soft matrices, cells preserve contractile beating for days in culture but do very little work. Optimal matrix leads to a strain match between cell and matrix, and suggests dynamic differences in intracellular protein structures. A novel `cysteine shotgun' method of labeling the in situ proteome reveals differences in assembly or conformation of several abundant cytoskeletal proteins, including vimentin, filamin and myosin.
Bookmarks Related papers MentionsView impact
The Journal of Cell Biology, 2004
Bookmarks Related papers MentionsView impact
Journal of Cell Science, 2008
Bookmarks Related papers MentionsView impact
Cell, 2006
Bookmarks Related papers MentionsView impact