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Cao S, Buchholz KS, Tan P, Stowe JC, Wang A, Fowler A, Knaus KR, Khalilimeybodi A, Zambon AC, Omens JH, Saucerman JJ, McCulloch AD. Differential sensitivity to longitudinal and transverse stretch mediates transcriptional responses in mouse neonatal ventricular myocytes. Am J Physiol Heart Circ Physiol 2024; 326:H370-H384. [PMID: 38063811 DOI: 10.1152/ajpheart.00562.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/11/2023] [Revised: 11/29/2023] [Accepted: 11/29/2023] [Indexed: 01/10/2024]
Abstract
To identify how cardiomyocyte mechanosensitive signaling pathways are regulated by anisotropic stretch, micropatterned mouse neonatal cardiomyocytes were stretched primarily longitudinally or transversely to the myofiber axis. Four hours of static, longitudinal stretch induced differential expression of 557 genes, compared with 30 induced by transverse stretch, measured using RNA-seq. A logic-based ordinary differential equation model of the cardiac myocyte mechanosignaling network, extended to include the transcriptional regulation and expression of 784 genes, correctly predicted measured expression changes due to anisotropic stretch with 69% accuracy. The model also predicted published transcriptional responses to mechanical load in vitro or in vivo with 63-91% accuracy. The observed differences between transverse and longitudinal stretch responses were not explained by differential activation of specific pathways but rather by an approximately twofold greater sensitivity to longitudinal stretch than transverse stretch. In vitro experiments confirmed model predictions that stretch-induced gene expression is more sensitive to angiotensin II and endothelin-1, via RhoA and MAP kinases, than to the three membrane ion channels upstream of calcium signaling in the network. Quantitative cardiomyocyte gene expression differs substantially with the axis of maximum principal stretch relative to the myofilament axis, but this difference is due primarily to differences in stretch sensitivity rather than to selective activation of mechanosignaling pathways.NEW & NOTEWORTHY Anisotropic stretch applied to micropatterned neonatal mouse ventricular myocytes induced markedly greater acute transcriptional responses when the major axis of stretch was parallel to the myofilament axis than when it was transverse. Analysis with a novel quantitative network model of mechanoregulated cardiomyocyte gene expression suggests that this difference is explained by higher cell sensitivity to longitudinal loading than transverse loading than by the activation of differential signaling pathways.
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Affiliation(s)
- Shulin Cao
- Department of Bioengineering, University of California San Diego, La Jolla, California, United States
| | - Kyle S Buchholz
- Department of Bioengineering, University of California San Diego, La Jolla, California, United States
| | - Philip Tan
- Department of Biomedical Engineering, University of Virginia, Charlottesville, Virginia, United States
| | - Jennifer C Stowe
- Department of Bioengineering, University of California San Diego, La Jolla, California, United States
| | - Ariel Wang
- Department of Bioengineering, University of California San Diego, La Jolla, California, United States
| | - Annabelle Fowler
- Department of Bioengineering, University of California San Diego, La Jolla, California, United States
| | - Katherine R Knaus
- Department of Bioengineering, University of California San Diego, La Jolla, California, United States
| | - Ali Khalilimeybodi
- Department of Mechanical and Aerospace Engineering, University of California San Diego, La Jolla, California, United States
| | - Alexander C Zambon
- Department of Biopharmaceutical Sciences, Keck Graduate Institute, Claremont, California, United States
| | - Jeffrey H Omens
- Department of Bioengineering, University of California San Diego, La Jolla, California, United States
- Department of Medicine, University of California San Diego, La Jolla, California, United States
| | - Jeffrey J Saucerman
- Department of Biomedical Engineering, University of Virginia, Charlottesville, Virginia, United States
| | - Andrew D McCulloch
- Department of Bioengineering, University of California San Diego, La Jolla, California, United States
- Department of Medicine, University of California San Diego, La Jolla, California, United States
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Abstract
The intact heart undergoes complex and multiscale remodelling processes in response to altered mechanical cues. Remodelling of the myocardium is regulated by a combination of myocyte and non-myocyte responses to mechanosensitive pathways, which can alter gene expression and therefore function in these cells. Cellular mechanotransduction and its downstream effects on gene expression are initially compensatory mechanisms during adaptations to the altered mechanical environment, but under prolonged and abnormal loading conditions, they can become maladaptive, leading to impaired function and cardiac pathologies. In this Review, we summarize mechanoregulated pathways in cardiac myocytes and fibroblasts that lead to altered gene expression and cell remodelling under physiological and pathophysiological conditions. Developments in systems modelling of the networks that regulate gene expression in response to mechanical stimuli should improve integrative understanding of their roles in vivo and help to discover new combinations of drugs and device therapies targeting mechanosignalling in heart disease.
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Affiliation(s)
- Jeffrey J Saucerman
- Department of Biomedical Engineering, University of Virginia, Charlottesville, VA, USA
| | - Philip M Tan
- Department of Biomedical Engineering, University of Virginia, Charlottesville, VA, USA
| | - Kyle S Buchholz
- Departments of Bioengineering and Medicine, University of California San Diego, La Jolla, CA, USA
| | - Andrew D McCulloch
- Departments of Bioengineering and Medicine, University of California San Diego, La Jolla, CA, USA.
| | - Jeffrey H Omens
- Departments of Bioengineering and Medicine, University of California San Diego, La Jolla, CA, USA
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Tan PM, Buchholz KS, Omens JH, McCulloch AD, Saucerman JJ. Predictive model identifies key network regulators of cardiomyocyte mechano-signaling. PLoS Comput Biol 2017; 13:e1005854. [PMID: 29131824 PMCID: PMC5703578 DOI: 10.1371/journal.pcbi.1005854] [Citation(s) in RCA: 44] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2017] [Revised: 11/27/2017] [Accepted: 10/26/2017] [Indexed: 12/11/2022] Open
Abstract
Mechanical strain is a potent stimulus for growth and remodeling in cells. Although many pathways have been implicated in stretch-induced remodeling, the control structures by which signals from distinct mechano-sensors are integrated to modulate hypertrophy and gene expression in cardiomyocytes remain unclear. Here, we constructed and validated a predictive computational model of the cardiac mechano-signaling network in order to elucidate the mechanisms underlying signal integration. The model identifies calcium, actin, Ras, Raf1, PI3K, and JAK as key regulators of cardiac mechano-signaling and characterizes crosstalk logic imparting differential control of transcription by AT1R, integrins, and calcium channels. We find that while these regulators maintain mostly independent control over distinct groups of transcription factors, synergy between multiple pathways is necessary to activate all the transcription factors necessary for gene transcription and hypertrophy. We also identify a PKG-dependent mechanism by which valsartan/sacubitril, a combination drug recently approved for treating heart failure, inhibits stretch-induced hypertrophy, and predict further efficacious pairs of drug targets in the network through a network-wide combinatorial search. Common stresses such as high blood pressure or heart attack can lead to heart failure, which afflicts over 25 million people worldwide. These stresses cause cardiomyocytes to grow and remodel, which may initially be beneficial but ultimately worsen heart function. Current heart failure drugs such as beta-blockers counteract biochemical cues prompting cardiomyocyte growth, yet mechanical cues to cardiomyocytes such as stretch are just as important in driving cardiac dysfunction. However, no pharmacological treatments have yet been approved that specifically target mechano-signaling, in part because it is not clear how cardiomyocytes integrate signals from multiple mechano-responsive sensors and pathways into their decision to grow. To address this challenge, we built a systems-level computational model that represents 125 interactions between 94 stretch-responsive signaling molecules. The model correctly predicts 134 of 172 previous independent experimental observations, and identifies the key regulators of stretch-induced cardiomyocyte remodeling. Although cardiomyocytes have many mechano-signaling pathways that function largely independently, we find that cooperation between them is necessary to cause growth and remodeling. We identify mechanisms by which a recently approved heart failure drug pair affects mechano-signaling, and we further predict additional pairs of drug targets that could be used to help reverse heart failure.
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Affiliation(s)
- Philip M. Tan
- Department of Biomedical Engineering, University of Virginia, Charlottesville, Virginia, United States of America
| | - Kyle S. Buchholz
- Departments of Bioengineering and Medicine, University of California San Diego, La Jolla, California, United States of America
| | - Jeffrey H. Omens
- Departments of Bioengineering and Medicine, University of California San Diego, La Jolla, California, United States of America
| | - Andrew D. McCulloch
- Departments of Bioengineering and Medicine, University of California San Diego, La Jolla, California, United States of America
| | - Jeffrey J. Saucerman
- Department of Biomedical Engineering, University of Virginia, Charlottesville, Virginia, United States of America
- * E-mail:
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Gan Z, Powell FL, Zambon AC, Buchholz KS, Fu Z, Ocorr K, Bodmer R, Moya EA, Stowe JC, Haddad GG, McCulloch AD. Transcriptomic analysis identifies a role of PI3K-Akt signalling in the responses of skeletal muscle to acute hypoxia in vivo. J Physiol 2017; 595:5797-5813. [PMID: 28688178 DOI: 10.1113/jp274556] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2017] [Accepted: 06/19/2017] [Indexed: 01/13/2023] Open
Abstract
KEY POINTS Changes in gene expression that occur within hours of exposure to hypoxia in in vivo skeletal muscles remain unexplored. Two hours of hypoxia caused significant down-regulation of extracellular matrix genes followed by a shift at 6 h to altered expression of genes associated with the nuclear lumen while respiratory and blood gases were stabilized. Enrichment analysis of mRNAs classified by stability rates suggests an attenuation of post-transcriptional regulation within hours of hypoxic exposure, where PI3K-Akt signalling was suggested to have a nodal role by pathway analysis. Experimental measurements and bioinformatic analyses suggested that the dephosphorylation of Akt after 2 h of hypoxic exposure might deactivate RNA-binding protein BRF1, hence resulting in the selective degradation of mRNAs. ABSTRACT The effects of acute hypoxia have been widely studied, but there are few studies of transcriptional responses to hours of hypoxia in vivo, especially in hypoxia-tolerant tissues like skeletal muscles. We used RNA-seq to analyse gene expression in plantaris muscles while monitoring respiration, arterial blood gases, and blood glucose in mice exposed to 8% O2 for 2 or 6 h. Rapid decreases in blood gases and a slower reduction in blood glucose suggest stress, which was accompanied by widespread changes in gene expression. Early down-regulation of genes associated with the extracellular matrix was followed by a shift to genes associated with the nuclear lumen. Most of the early down-regulated genes had mRNA half-lives longer than 2 h, suggesting a role for post-transcriptional regulation. These transcriptional changes were enriched in signalling pathways in which the PI3K-Akt signalling pathway was identified as a hub. Our analyses indicated that gene targets of PI3K-Akt but not HIF were enriched in early transcriptional responses to hypoxia. Among the PI3K-Akt targets, 75% could be explained by a deactivation of adenylate-uridylate-rich element (ARE)-binding protein BRF1, a target of PI3K-Akt. Consistent decreases in the phosphorylation of Akt and BRF1 were experimentally confirmed following 2 h of hypoxia. These results suggest that the PI3K-Akt signalling pathway might play a role in responses induced by acute hypoxia in skeletal muscles, partially through the dephosphorylation of ARE-binding protein BRF1.
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Affiliation(s)
- Zhuohui Gan
- School of Basic Medical Sciences, Wenzhou Medical University, Wenzhou, 325035, Zhejiang, China.,Department of Bioengineering, University of California San Diego, La Jolla, CA, 92093, USA
| | - Frank L Powell
- Department of Medicine, University of California San Diego, La Jolla, CA, 92093, USA
| | - Alexander C Zambon
- Department of Biopharmaceutical Sciences, Keck Graduate Institute, Claremont, CA, 91711, USA
| | - Kyle S Buchholz
- Department of Bioengineering, University of California San Diego, La Jolla, CA, 92093, USA
| | - Zhenxing Fu
- Department of Medicine, University of California San Diego, La Jolla, CA, 92093, USA
| | - Karen Ocorr
- Development, Aging and Regeneration Program, Sanford Burnham Prebys Medical Discovery Institute, La Jolla, CA, 92037, USA
| | - Rolf Bodmer
- Development, Aging and Regeneration Program, Sanford Burnham Prebys Medical Discovery Institute, La Jolla, CA, 92037, USA
| | - Esteban A Moya
- Department of Medicine, University of California San Diego, La Jolla, CA, 92093, USA
| | - Jennifer C Stowe
- Department of Bioengineering, University of California San Diego, La Jolla, CA, 92093, USA
| | - Gabriel G Haddad
- Department of Pediatrics, University of California San Diego, La Jolla, CA, 92093, USA.,Department of Neurosciences, University of California San Diego, La Jolla, CA, 92093, USA.,Rady Children's Hospital San Diego, 3020 Children's Way, San Diego, CA, 92123, USA
| | - Andrew D McCulloch
- Department of Bioengineering, University of California San Diego, La Jolla, CA, 92093, USA.,Department of Medicine, University of California San Diego, La Jolla, CA, 92093, USA
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Banerjee I, Zhang J, Moore-Morris T, Pfeiffer E, Buchholz KS, Liu A, Ouyang K, Stroud MJ, Gerace L, Evans SM, McCulloch A, Chen J. Targeted ablation of nesprin 1 and nesprin 2 from murine myocardium results in cardiomyopathy, altered nuclear morphology and inhibition of the biomechanical gene response. PLoS Genet 2014; 10:e1004114. [PMID: 24586179 PMCID: PMC3930490 DOI: 10.1371/journal.pgen.1004114] [Citation(s) in RCA: 101] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2013] [Accepted: 11/27/2013] [Indexed: 11/17/2022] Open
Abstract
Recent interest has focused on the importance of the nucleus and associated nucleoskeleton in regulating changes in cardiac gene expression in response to biomechanical load. Mutations in genes encoding proteins of the inner nuclear membrane and nucleoskeleton, which cause cardiomyopathy, also disrupt expression of a biomechanically responsive gene program. Furthermore, mutations in the outer nuclear membrane protein Nesprin 1 and 2 have been implicated in cardiomyopathy. Here, we identify for the first time a role for the outer nuclear membrane proteins, Nesprin 1 and Nesprin 2, in regulating gene expression in response to biomechanical load. Ablation of both Nesprin 1 and 2 in cardiomyocytes, but neither alone, resulted in early onset cardiomyopathy. Mutant cardiomyocytes exhibited altered nuclear positioning, shape, and chromatin positioning. Loss of Nesprin 1 or 2, or both, led to impairment of gene expression changes in response to biomechanical stimuli. These data suggest a model whereby biomechanical signals are communicated from proteins of the outer nuclear membrane, to the inner nuclear membrane and nucleoskeleton, to result in changes in gene expression required for adaptation of the cardiomyocyte to changes in biomechanical load, and give insights into etiologies underlying cardiomyopathy consequent to mutations in Nesprin 1 and 2.
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Affiliation(s)
- Indroneal Banerjee
- Department of Medicine, University of California-San Diego, La Jolla, California, United States of America
| | - Jianlin Zhang
- Department of Medicine, University of California-San Diego, La Jolla, California, United States of America
| | - Thomas Moore-Morris
- Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California-San Diego, La Jolla, California, United States of America
| | - Emily Pfeiffer
- Department of Bioengineering, University of California-San Diego, La Jolla, California, United States of America
| | - Kyle S Buchholz
- Department of Bioengineering, University of California-San Diego, La Jolla, California, United States of America
| | - Ao Liu
- Department of Medicine, University of California-San Diego, La Jolla, California, United States of America
| | - Kunfu Ouyang
- Department of Medicine, University of California-San Diego, La Jolla, California, United States of America ; Drug Discovery Center, Key Laboratory of Chemical Genomics, Peking University Shenzhen Graduate School, Shenzhen, China
| | - Matthew J Stroud
- Department of Medicine, University of California-San Diego, La Jolla, California, United States of America
| | - Larry Gerace
- Department of Cell and Molecular Biology, The Scripps Research Institute, La Jolla, California, United States of America
| | - Sylvia M Evans
- Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California-San Diego, La Jolla, California, United States of America
| | - Andrew McCulloch
- Department of Medicine, University of California-San Diego, La Jolla, California, United States of America ; Department of Bioengineering, University of California-San Diego, La Jolla, California, United States of America
| | - Ju Chen
- Department of Medicine, University of California-San Diego, La Jolla, California, United States of America
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Abstract
Cytokine-neutralizing antibodies are used in treating a broad range of inflammatory conditions. We demonstrate that monoclonal antibodies against interleukin-1β and tumor necrosis factor-α were still active when conjugated to high molecular weight polysaccharides. These polysaccharides are hydrophilic, but their size makes them unable to circulate in the bloodstream when delivered to tissues, opening up the possibility of localized treatment of inflammatory conditions. To explore this new class of protein-polysaccharide conjugates, we covalently modified interleukin-1β and tumor necrosis factor-α monoclonal antibodies with high molecular weight hyaluronic acid and carboxymethylcellulose. Rigorous purification using dialysis with a 300 kDa-cutoff membrane removed unconjugated monoclonal antibodies. We characterized the composition of the constructs and demonstrated using molecular binding affinity measurements and cell assays that the conjugates were capable of binding proinflammatory cytokines. The binding affinities of both the unconjugated antibodies for their cytokines were measured to be approximately 120 pM. While all conjugates had pM-level binding constants, they ranged from 40 pM for the hyaluronic acid-(anti-interleukin-1β) conjugate to 412 pM for the carboxymethylcellulose-(anti-interleukin-1β) conjugate. Interestingly, the dissociation time constants varied more than the association time constants, suggesting that conjugation to a high molecular weight polysaccharide did not interfere with the formation of the antibody-cytokine complex but could stabilize or destabilize it once formed. Conjugation of cytokine-neutralizing antibodies to high molecular weight polymers represents a novel method of delivering anticytokine therapeutics that may avoid many of the complications associated with systemic delivery.
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Affiliation(s)
- Liang Tso Sun
- Departments of Biomedical Engineering and Chemistry, Carnegie Mellon University, Pittsburgh, PA 15213, USA
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