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Morris T, Sue E, Geniesse C, Brieher WM, Tang VW. Synaptopodin stress fiber and contractomere at the epithelial junction. J Cell Biol 2022; 221:213132. [PMID: 35416930 PMCID: PMC9011326 DOI: 10.1083/jcb.202011162] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2020] [Revised: 10/07/2021] [Accepted: 02/09/2022] [Indexed: 12/27/2022] Open
Abstract
The apical junction of epithelial cells can generate force to control cell geometry and perform contractile processes while maintaining barrier function and adhesion. Yet, the structural basis for force generation at the apical junction is not fully understood. Here, we describe two synaptopodin-dependent actomyosin structures that are spatially, temporally, and structurally distinct. The first structure is formed by the retrograde flow of synaptopodin initiated at the apical junction, creating a sarcomeric stress fiber that lies parallel to the apical junction. Contraction of the apical stress fiber is associated with either clustering of membrane components or shortening of junctional length. Upon junction maturation, apical stress fibers are disassembled. In mature epithelial monolayer, a motorized “contractomere” capable of “walking the junction” is formed at the junctional vertex. Actomyosin activities at the contractomere produce a compressive force evident by actin filament buckling and measurement with a new α-actinin-4 force sensor. The motility of contractomeres can adjust junctional length and change cell packing geometry during cell extrusion and intercellular movement. We propose a model of epithelial homeostasis that utilizes contractomere motility to support junction rearrangement while preserving the permeability barrier.
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Affiliation(s)
- Timothy Morris
- Department of Cell and Developmental Biology, University of Illinois, Urbana-Champaign, IL
| | - Eva Sue
- Department of Cell and Developmental Biology, University of Illinois, Urbana-Champaign, IL
| | - Caleb Geniesse
- Department of Cell and Developmental Biology, University of Illinois, Urbana-Champaign, IL
| | - William M Brieher
- Department of Cell and Developmental Biology, University of Illinois, Urbana-Champaign, IL
| | - Vivian W Tang
- Department of Cell and Developmental Biology, University of Illinois, Urbana-Champaign, IL
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2
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Tang VW. Collagen, stiffness, and adhesion: the evolutionary basis of vertebrate mechanobiology. Mol Biol Cell 2020; 31:1823-1834. [PMID: 32730166 PMCID: PMC7525820 DOI: 10.1091/mbc.e19-12-0709] [Citation(s) in RCA: 40] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2020] [Revised: 05/11/2020] [Accepted: 05/28/2020] [Indexed: 01/09/2023] Open
Abstract
The emergence of collagen I in vertebrates resulted in a dramatic increase in the stiffness of the extracellular environment, supporting long-range force propagation and the development of low-compliant tissues necessary for the development of vertebrate traits including pressurized circulation and renal filtration. Vertebrates have also evolved integrins that can bind to collagens, resulting in the generation of higher tension and more efficient force transmission in the extracellular matrix. The stiffer environment provides an opportunity for the vertebrates to create new structures such as the stress fibers, new cell types such as endothelial cells, new developmental processes such as neural crest delamination, and new tissue organizations such as the blood-brain barrier. Molecular players found only in vertebrates allow the modification of conserved mechanisms as well as the design of novel strategies that can better serve the physiological needs of the vertebrates. These innovations collectively contribute to novel morphogenetic behaviors and unprecedented increases in the complexities of tissue mechanics and functions.
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Affiliation(s)
- Vivian W. Tang
- Department of Cell and Developmental Biology, University of Illinois, Urbana–Champaign, Urbana, IL 61801
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3
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Guo S, Zhang Y, Wei C, Shi L, Feng Y. The E3 Ubiquitin Ligase MARCH8 Regulates TNF-α-Induced Apoptosis in Hippocampal Neurons by Targeting Myosin Light Chain 2 for Degradation. Anat Rec (Hoboken) 2019; 302:2271-2278. [PMID: 31443122 DOI: 10.1002/ar.24238] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2018] [Revised: 04/28/2019] [Accepted: 05/20/2019] [Indexed: 12/14/2022]
Abstract
Tumor necrosis factor-α (TNF-α) is an important inflammatory cytokine that plays a key role in neuronal damage. Elevated expression of TNF-α is associated with numerous neurodegenerative diseases including Alzheimer's Disease and Parkinson's Disease. However, the specific mechanism of the signaling events that trigger TNF-α-mediated neurotoxicity remain unknown. In this study, we report that intracerebroventricular injection of TNF-α in rat hippocampal neurons down-regulates MLC2 and up-regulates MARCH8, an essential light chain and regulatory myosin light chain of NM Myosin II, respectively. MARCH8 overexpression attenuates the degradation of MLC2 by promoting its ubiquitination and degradation. Inhibition of MARCH8 by siRNA blocks caspase-3 activation and apoptosis signaling, suggesting that TNF-α-induced apoptosis of neurons is partially dependent on the accumulation of MARCH8 and the ubiquitination of MLC2. Taken together, our data not only clarify the function of MARCH8 in TNF-α-induced neurotoxicity, but also demonstrates that TNF-α promotes the MARCH8-MLC2 mediated apoptosis of hippocampal neurons. Anat Rec, 302:2271-2278, 2019. © 2019 American Association for Anatomy.
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Affiliation(s)
- Shanglin Guo
- The Affiliated Hospital of Medical College, QingDao University, Qingdao, China
| | - Yongqing Zhang
- Qilu Hospital of Shandong University (Qingdao), Qingdao, China
| | - Chaoping Wei
- Qingdao Women and Children's Hospital, Qingdao, China
| | - Lu Shi
- 401 Hospital of the People's Liberation Army, Qingdao, China
| | - Yugong Feng
- The Affiliated Hospital of Medical College, QingDao University, Qingdao, China
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4
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Galluzzi M, Schulte C, Milani P, Podestà A. Imidazolium-Based Ionic Liquids Affect Morphology and Rigidity of Living Cells: An Atomic Force Microscopy Study. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2018; 34:12452-12462. [PMID: 30213187 DOI: 10.1021/acs.langmuir.8b01554] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
The study of the toxicity, biocompatibility, and environmental sustainability of room-temperature ionic liquids (ILs) is still in its infancy. Understanding the impact of ILs on living organisms, especially from the aquatic ecosystem, is urgent, since large amounts of these substances are starting to be employed as solvents in industrial chemical processes, and on the other side, evidence of toxic effects of ILs on microorganisms and single cells have been observed. To date, the toxicity of ILs has been investigated by means of macroscopic assays aimed at characterizing the effective concentrations (like the EC50) that cause the death of a significant fraction of the population of microorganisms and cells. These studies allow us to identify the cell membrane as the first target of the IL interaction, whose effectiveness was correlated to the lipophilicity of the cation, i.e., to the length of the lateral alkyl chain. Our study aimed at investigating the molecular mechanisms underpinning the interaction of ILs with living cells. To this purpose, we carried out a combined topographic and mechanical analysis by atomic force microscopy of living breast metastatic cancer cells (MDA-MB-231) upon interaction with imidazolium-based ILs. We showed that ILs are able to induce modifications of the overall rigidity (effective Young's modulus) and morphology of the cells. Our results demonstrate that ILs act on the physical properties of the outer cell layer (the membrane linked to the actin cytoskeleton), already at concentrations below the EC50. These potentially toxic effects are stronger at higher IL concentrations, as well as with longer lateral chains in the cation.
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Affiliation(s)
- Massimiliano Galluzzi
- Shenzhen Key Laboratory of Nanobiomechanics , Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences , Shenzhen 518055 , Guangdong , China
- C.I.Ma.I.Na and Dipartimento di Fisica "Aldo Pontremoli" , Università degli Studi di Milano , via Celoria 16 , 20133 Milano , Italy
| | - Carsten Schulte
- C.I.Ma.I.Na and Dipartimento di Fisica "Aldo Pontremoli" , Università degli Studi di Milano , via Celoria 16 , 20133 Milano , Italy
| | - Paolo Milani
- C.I.Ma.I.Na and Dipartimento di Fisica "Aldo Pontremoli" , Università degli Studi di Milano , via Celoria 16 , 20133 Milano , Italy
| | - Alessandro Podestà
- C.I.Ma.I.Na and Dipartimento di Fisica "Aldo Pontremoli" , Università degli Studi di Milano , via Celoria 16 , 20133 Milano , Italy
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5
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Vitale ML, Pelletier RM. The anterior pituitary gap junctions: potential targets for toxicants. Reprod Toxicol 2018; 79:72-78. [PMID: 29906538 DOI: 10.1016/j.reprotox.2018.06.003] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2018] [Revised: 05/31/2018] [Accepted: 06/07/2018] [Indexed: 01/16/2023]
Abstract
The anterior pituitary regulates endocrine organs and physiological activities in the body. Environmental pollutants and drugs deleterious to the endocrine system may affect anterior pituitary activity through direct action on anterior pituitary cells. Within the gland, endocrine and folliculostellate cells are organized into and function as individual tridimensional networks, each network regulating its activity by coordinating the connected cells' responses to physiological or pathological cues. The gap junctions connecting endocrine cells and/or folliculostellate cells allow transmission of information among cells that is necessary for adequate network function. Toxicants may affect gap junctions as well as the physiology of the anterior pituitary. However, whether toxicants effects on anterior pituitary hormone secretion involve gap junctions is unknown. The folliculostellate cell gap junctions are sensitive to hormones, cytokines and growth factors. These cells may be an interesting experimental model for evaluating whether toxicants target anterior pituitary gap junctions.
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Affiliation(s)
- María Leiza Vitale
- Département de pathologie et biologie cellulaire, Faculté de Médecine, Université de Montréal, Montréal, QC Canada.
| | - R-Marc Pelletier
- Département de pathologie et biologie cellulaire, Faculté de Médecine, Université de Montréal, Montréal, QC Canada
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Penke LR, Speth JM, Dommeti VL, White ES, Bergin IL, Peters-Golden M. FOXM1 is a critical driver of lung fibroblast activation and fibrogenesis. J Clin Invest 2018; 128:2389-2405. [PMID: 29733296 DOI: 10.1172/jci87631] [Citation(s) in RCA: 76] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2016] [Accepted: 03/20/2018] [Indexed: 12/23/2022] Open
Abstract
While the transcription factor forkhead box M1 (FOXM1) is well known as a proto-oncogene, its potential role in lung fibroblast activation has never been explored. Here, we show that FOXM1 is more highly expressed in fibrotic than in normal lung fibroblasts in humans and mice. FOXM1 was required not only for cell proliferation in response to mitogens, but also for myofibroblast differentiation and apoptosis resistance elicited by TGF-β. The lipid mediator PGE2, acting via cAMP signaling, was identified as an endogenous negative regulator of FOXM1. Finally, genetic deletion of FOXM1 in fibroblasts or administration of the FOXM1 inhibitor Siomycin A in a therapeutic protocol attenuated bleomycin-induced pulmonary fibrosis. Our results identify FOXM1 as a driver of lung fibroblast activation and underscore the therapeutic potential of targeting FOXM1 for pulmonary fibrosis.
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Affiliation(s)
- Loka R Penke
- Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine
| | - Jennifer M Speth
- Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine
| | - Vijaya L Dommeti
- Michigan Center for Translational Pathology, Department of Pathology, and
| | - Eric S White
- Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine
| | - Ingrid L Bergin
- Unit for Laboratory Animal Medicine, University of Michigan, Ann Arbor, Michigan, USA
| | - Marc Peters-Golden
- Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine
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7
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Wang Y, Xu Y, Liu Q, Zhang Y, Gao Z, Yin M, Jiang N, Cao G, Yu B, Cao Z, Kou J. Myosin IIA-related Actomyosin Contractility Mediates Oxidative Stress-induced Neuronal Apoptosis. Front Mol Neurosci 2017; 10:75. [PMID: 28352215 PMCID: PMC5348499 DOI: 10.3389/fnmol.2017.00075] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2016] [Accepted: 03/03/2017] [Indexed: 12/22/2022] Open
Abstract
Oxidative stress-induced neuronal apoptosis plays an important role in the progression of central nervous system (CNS) diseases. In our study, when neuronal cells were exposed to hydrogen peroxide (H2O2), an exogenous oxidant, cell apoptosis was observed with typical morphological changes including membrane blebbing, neurite retraction and cell contraction. The actomyosin system is considered to be responsible for the morphological changes, but how exactly it regulates oxidative stress-induced neuronal apoptosis and the distinctive functions of different myosin II isoforms remain unclear. We demonstrate that myosin IIA was required for neuronal contraction, while myosin IIB was required for neuronal outgrowth in normal conditions. During H2O2-induced neuronal apoptosis, myosin IIA, rather than IIB, interacted with actin filaments to generate contractile forces that lead to morphological changes. Moreover, myosin IIA knockout using clustered regularly interspaced short palindromic repeats/CRISPR-associated protein-9 nuclease (CRISPR/Cas9) reduced H2O2-induced neuronal apoptosis and the associated morphological changes. We further demonstrate that caspase-3/Rho-associated kinase 1 (ROCK1) dependent phosphorylation of myosin light chain (MLC) was required for the formation of the myosin IIA-actin complex. Meanwhile, either inhibition of myosin II ATPase with blebbistatin or knockdown of myosin IIA with siRNA reversely attenuated caspase-3 activation, suggesting a positive feedback loop during oxidative stress-induced apoptosis. Based on our observation, myosin IIA-actin complex contributes to actomyosin contractility and is associated with the positive feedback loop of caspase-3/ROCK1/MLC pathway. This study unravels the biochemical and mechanistic mechanisms during oxidative stress-induced neuronal apoptosis and may be applicable for the development of therapies for CNS diseases.
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Affiliation(s)
- Yan Wang
- State Key Laboratory of Natural Products, Jiangsu Key Laboratory of TCM Evaluation and Translational Research, Department of Complex Prescription of TCM, China Pharmaceutical University Nanjing, China
| | - Yingqiong Xu
- State Key Laboratory of Natural Products, Jiangsu Key Laboratory of TCM Evaluation and Translational Research, Department of Complex Prescription of TCM, China Pharmaceutical University Nanjing, China
| | - Qian Liu
- Department of Neurology, Jinling Hospital, Nanjing University School of Medicine Nanjing, China
| | - Yuanyuan Zhang
- State Key Laboratory of Natural Products, Jiangsu Key Laboratory of TCM Evaluation and Translational Research, Department of Complex Prescription of TCM, China Pharmaceutical University Nanjing, China
| | - Zhen Gao
- Department of Medicine-Ather and Lipo, Baylor College of Medicine Houston, TX, USA
| | - Mingzhu Yin
- Department of Pathology, Yale School of Medicine New Haven, CT, USA
| | - Nan Jiang
- State Key Laboratory of Natural Products, Jiangsu Key Laboratory of TCM Evaluation and Translational Research, Department of Complex Prescription of TCM, China Pharmaceutical University Nanjing, China
| | - Guosheng Cao
- State Key Laboratory of Natural Products, Jiangsu Key Laboratory of TCM Evaluation and Translational Research, Department of Complex Prescription of TCM, China Pharmaceutical University Nanjing, China
| | - Boyang Yu
- State Key Laboratory of Natural Products, Jiangsu Key Laboratory of TCM Evaluation and Translational Research, Department of Complex Prescription of TCM, China Pharmaceutical University Nanjing, China
| | - Zhengyu Cao
- State Key Laboratory of Natural Products, Jiangsu Key Laboratory of TCM Evaluation and Translational Research, Department of Complex Prescription of TCM, China Pharmaceutical University Nanjing, China
| | - Junping Kou
- State Key Laboratory of Natural Products, Jiangsu Key Laboratory of TCM Evaluation and Translational Research, Department of Complex Prescription of TCM, China Pharmaceutical University Nanjing, China
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8
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Multi-parametric imaging of cell heterogeneity in apoptosis analysis. Methods 2017; 112:105-123. [DOI: 10.1016/j.ymeth.2016.07.003] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2016] [Revised: 06/14/2016] [Accepted: 07/05/2016] [Indexed: 12/13/2022] Open
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9
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Zaidel-Bar R, Zhenhuan G, Luxenburg C. The contractome – a systems view of actomyosin contractility in non-muscle cells. J Cell Sci 2015; 128:2209-17. [DOI: 10.1242/jcs.170068] [Citation(s) in RCA: 69] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2015] [Accepted: 04/27/2015] [Indexed: 12/21/2022] Open
Abstract
ABSTRACT
Actomyosin contractility is a highly regulated process that affects many fundamental biological processes in each and every cell in our body. In this Cell Science at a Glance article and the accompanying poster, we mined the literature and databases to map the contractome of non-muscle cells. Actomyosin contractility is involved in at least 49 distinct cellular functions that range from providing cell architecture to signal transduction and nuclear activity. Containing over 100 scaffolding and regulatory proteins, the contractome forms a highly complex network with more than 230 direct interactions between its components, 86 of them involving phosphorylation. Mapping these interactions, we identify the key regulatory pathways involved in the assembly of actomyosin structures and in activating myosin to produce contractile forces within non-muscle cells at the exact time and place necessary for cellular function.
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Affiliation(s)
- Ronen Zaidel-Bar
- Mechanobiology Institute, National University of Singapore, T-lab building #05-01, 5A Engineering Drive 1, 117411, Singapore
| | - Guo Zhenhuan
- Mechanobiology Institute, National University of Singapore, T-lab building #05-01, 5A Engineering Drive 1, 117411, Singapore
| | - Chen Luxenburg
- Department of Cell and Developmental Biology, Sackler Faculty of Medicine, Tel Aviv University, P.O. Box 39040, Tel Aviv 69978, Israel
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10
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Betapudi V. Life without double-headed non-muscle myosin II motor proteins. Front Chem 2014; 2:45. [PMID: 25072053 PMCID: PMC4083560 DOI: 10.3389/fchem.2014.00045] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2014] [Accepted: 06/19/2014] [Indexed: 11/20/2022] Open
Abstract
Non-muscle myosin II motor proteins (myosin IIA, myosin IIB, and myosin IIC) belong to a class of molecular motor proteins that are known to transduce cellular free-energy into biological work more efficiently than man-made combustion engines. Nature has given a single myosin II motor protein for lower eukaryotes and multiple for mammals but none for plants in order to provide impetus for their life. These specialized nanomachines drive cellular activities necessary for embryogenesis, organogenesis, and immunity. However, these multifunctional myosin II motor proteins are believed to go awry due to unknown reasons and contribute for the onset and progression of many autosomal-dominant disorders, cataract, deafness, infertility, cancer, kidney, neuronal, and inflammatory diseases. Many pathogens like HIV, Dengue, hepatitis C, and Lymphoma viruses as well as Salmonella and Mycobacteria are now known to take hostage of these dedicated myosin II motor proteins for their efficient pathogenesis. Even after four decades since their discovery, we still have a limited knowledge of how these motor proteins drive cell migration and cytokinesis. We need to enrich our current knowledge on these fundamental cellular processes and develop novel therapeutic strategies to fix mutated myosin II motor proteins in pathological conditions. This is the time to think how to relieve the hijacked myosins from pathogens in order to provide a renewed impetus for patients' life. Understanding how to steer these molecular motors in proliferating and differentiating stem cells will improve stem cell based-therapeutics development. Given the plethora of cellular activities non-muscle myosin motor proteins are involved in, their importance is apparent for human life.
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Affiliation(s)
- Venkaiah Betapudi
- Department of Cellular and Molecular Medicine, Lerner Research Institute, Cleveland Clinic Cleveland, OH, USA ; Department of Physiology and Biophysics, Case Western Reserve University Cleveland, OH, USA
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11
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Ma X, Adelstein RS. A point mutation in Myh10 causes major defects in heart development and body wall closure. ACTA ACUST UNITED AC 2014; 7:257-65. [PMID: 24825879 DOI: 10.1161/circgenetics.113.000455] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND The 3 isoforms of nonmuscle myosin (NM) II (NMII-A, NMII-B, and NMII-C) play various roles during mouse embryonic development. Previous work, using knockout and hypomorphic mice, showed that Myh10 encoding myosin heavy chain II-B is critical for cardiac and brain development. Ablating or decreasing NMII-B by 80% results in cardiac (ventricular septal defect, double outlet of the right ventricle) and brain defects but not midline fusion defects. Neither NMII-A nor II-C seems to play roles in early myocardial development. METHODS AND RESULTS We had previously generated point mutant knock-in mice and now report novel findings as a result of expressing motor-deficient NMII-B at wild-type levels. Homozygous mice die at embryonic day 14.5 in cardiac failure, exhibiting abnormalities not seen in NMII-B null and hypomorphic mice: a failure in midline fusion resulting in a cleft palate, ectopia cordis, and a large omphalocele. Fusion of the sternum and endocardial cushions is impaired in the mutant mice associated with a failure in apoptosis of the mesenchymal cells. Failure to disassemble myocyte cell-cell adhesions during cardiac outflow tract development contributes to impaired outflow tract myocardialization and displacement of the aorta to the right ventricle. CONCLUSIONS Expression of motor-impaired NMII-B disrupts normal ventral body wall closure because of a dominant-negative effect. This is not because of the loss of NMII-B function but rather a gain-of-function resulting from prolonged cross-linking of NMII-B to actin filaments, thereby interfering with the dynamics of actomyosin cytoskeletal structure. Furthermore, impaired NMII-B motor activity inhibits outflow tract myocardialization, leading to mislocalization of the aorta.
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Affiliation(s)
- Xuefei Ma
- From the Laboratory of Molecular Cardiology, Genetics & Developmental Biology Center, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD.
| | - Robert S Adelstein
- From the Laboratory of Molecular Cardiology, Genetics & Developmental Biology Center, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD
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12
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Intrinsic-mediated caspase activation is essential for cardiomyocyte hypertrophy. Proc Natl Acad Sci U S A 2013; 110:E4079-87. [PMID: 24101493 DOI: 10.1073/pnas.1315587110] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Cardiomyocyte hypertrophy is the cellular response that mediates pathologic enlargement of the heart. This maladaptation is also characterized by cell behaviors that are typically associated with apoptosis, including cytoskeletal reorganization and disassembly, altered nuclear morphology, and enhanced protein synthesis/translation. Here, we investigated the requirement of apoptotic caspase pathways in mediating cardiomyocyte hypertrophy. Cardiomyocytes treated with hypertrophy agonists displayed rapid and transient activation of the intrinsic-mediated cell death pathway, characterized by elevated levels of caspase 9, followed by caspase 3 protease activity. Disruption of the intrinsic cell death pathway at multiple junctures led to a significant inhibition of cardiomyocyte hypertrophy during agonist stimulation, with a corresponding reduction in the expression of known hypertrophic markers (atrial natriuretic peptide) and transcription factor activity [myocyte enhancer factor-2, nuclear factor kappa B (NF-κB)]. Similarly, in vivo attenuation of caspase activity via adenoviral expression of the biologic effector caspase inhibitor p35 blunted cardiomyocyte hypertrophy in response to agonist stimulation. Treatment of cardiomyocytes with procaspase 3 activating compound 1, a small-molecule activator of caspase 3, resulted in a robust induction of the hypertrophy response in the absence of any agonist stimulation. These results suggest that caspase-dependent signaling is necessary and sufficient to promote cardiomyocyte hypertrophy. These results also confirm that cell death signal pathways behave as active remodeling agents in cardiomyocytes, independent of inducing an apoptosis response.
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13
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Leong S, McKay MJ, Christopherson RI, Baxter RC. Biomarkers of breast cancer apoptosis induced by chemotherapy and TRAIL. J Proteome Res 2011; 11:1240-50. [PMID: 22133146 DOI: 10.1021/pr200935y] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Treatment of breast cancer is complex and challenging due to the heterogeneity of the disease. To avoid significant toxicity and adverse side-effects of chemotherapy in patients who respond poorly, biomarkers predicting therapeutic response are essential. This study has utilized a proteomic approach integrating 2D-DIGE, LC-MS/MS, and bioinformatics to analyze the proteome of breast cancer (ZR-75-1 and MDA-MB-231) and breast epithelial (MCF-10A) cell lines induced to undergo apoptosis using a combination of doxorubicin and TRAIL administered in sequence (Dox-TRAIL). Apoptosis induction was confirmed using a caspase-3 activity assay. Comparative proteomic analysis between whole cell lysates of Dox-TRAIL and control samples revealed 56 differentially expressed spots (≥2-fold change and p < 0.05) common to at least two cell lines. Of these, 19 proteins were identified yielding 11 unique protein identities: CFL1, EIF5A, HNRNPK, KRT8, KRT18, LMNA, MYH9, NACA, RPLP0, RPLP2, and RAD23B. A subset of the identified proteins was validated by selected reaction monitoring (SRM) and Western blotting. Pathway analysis revealed that the differentially abundant proteins were associated with cell death, cellular organization, integrin-linked kinase signaling, and actin cytoskeleton signaling pathways. The 2D-DIGE analysis has yielded candidate biomarkers of response to treatment in breast cancer cell models. Their clinical utility will depend on validation using patient breast biopsies pre- and post-treatment with anticancer drugs.
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Affiliation(s)
- Sharon Leong
- Kolling Institute of Medical Research, The University of Sydney , Royal North Shore Hospital, St Leonards, NSW 2065, Australia
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14
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Myosin IIB deficiency in embryonic fibroblasts affects regulators and core members of the par polarity complex. Histochem Cell Biol 2011; 136:245-66. [PMID: 21785947 DOI: 10.1007/s00418-011-0840-0] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/06/2011] [Indexed: 10/24/2022]
Abstract
Wild-type (WT) and myosin heavy chain IIB null [MHCIIB (-/-)] embryonic fibroblasts were used as an experimental model to assess the role of the isoform B of myosin II (MII) in the regulation of the cell shape and intrinsic polarity. Genetic ablation of MHCIIB causes a persistent albeit, unstable protrusive activity in embryonic fibroblasts (Lo et al. in Nonmuscle myosin IIB is involved in the guidance of fibroblast migration. Mol Biol Cell 15:982-989, 2004). Here, we show that MHCIIB-deficient fibroblasts are characterized by a sustained guanine nucleotide exchange factor (GEF)-dependent activation of the small GTPase Rac-1 that is responsible for the continual lamellipodium formation. Moreover, we observed a sustained PKC-ζ activation and an increased association of cortactin with the plasma membrane in the MHCIIB (-/-) cells that were also dependent on GEF-mediated Rac-1 activation. Rac-1 activation and its downstream effects were induced in WT fibroblasts by inhibiting MII ATPase and crosslinking activities, suggesting that an altered actin-MII interaction favours Rac-1 activation, regardless of the MII isoform implicated. In addition, we found MIIB isoform-specific effects that were independent of Rac-1 activation. MHCIIA interacts with cortactin whereas MHCIIB does not. By contrast, MHCIIB interacts with Lgl1, a member of the Scribble/Dlg/Lgl polarity complex, whereas MHCIIA does not. MHCIIB (-/-) fibroblasts exhibited deregulated endogenous levels of the Par polarity complex members, Par3 and Par6. Together, the data show that MHCIIB deficiency causes imbalances in signalling pathways that are responsible for cell polarity determination. The results suggest that these pathways are targets of MIIB in the regulation of the cell's shape and polarity.
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