1
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Liu P, Liu Y, Zhou J. Ciliary mechanosensation - roles of polycystins and mastigonemes. J Cell Sci 2023; 136:286945. [PMID: 36752106 DOI: 10.1242/jcs.260565] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/09/2023] Open
Abstract
Cilia are surface-exposed organelles that provide motility and sensory functions for cells, and it is widely believed that mechanosensation can be mediated through cilia. Polycystin-1 and -2 (PC-1 and PC-2, respectively) are transmembrane proteins that can localize to cilia; however, the molecular mechanisms by which polycystins contribute to mechanosensation are still controversial. Studies detail two prevailing models for the molecular roles of polycystins on cilia; one stresses the mechanosensation capabilities and the other unveils their ligand-receptor nature. The discovery that polycystins interact with mastigonemes, the 'hair-like' protrusions of flagella, is a novel finding in identifying the interactors of polycystins in cilia. While the functions of polycystins proposed by both models may coexist in cilia, it is hoped that a precise understanding of the mechanism of action of polycystins can be achieved by uncovering their distribution and interacting factors inside cilia. This will hopefully provide a satisfying answer to the pathogenesis of autosomal dominant polycystic kidney disease (ADPKD), which is caused by mutations in PC-1 and PC-2. In this Review, we discuss the characteristics of polycystins in the context of cilia and summarize the functions of mastigonemes in unicellular ciliates. Finally, we compare flagella and molecular features of PC-2 between unicellular and multicellular organisms, with the aim of providing new insights into the ciliary roles of polycystins in general.
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Affiliation(s)
- Peiwei Liu
- Shandong Provincial Key Laboratory of Animal Resistance Biology , College of Life Sciences in Shandong Normal University, Jinan 250358, China
| | - Ying Liu
- Shandong Provincial Key Laboratory of Animal Resistance Biology , College of Life Sciences in Shandong Normal University, Jinan 250358, China
| | - Jun Zhou
- Shandong Provincial Key Laboratory of Animal Resistance Biology , College of Life Sciences in Shandong Normal University, Jinan 250358, China.,College of Life Sciences, Nankai University, Tianjin 300071, China
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2
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Djenoune L, Mahamdeh M, Truong TV, Nguyen CT, Fraser SE, Brueckner M, Howard J, Yuan S. Cilia function as calcium-mediated mechanosensors that instruct left-right asymmetry. Science 2023; 379:71-78. [PMID: 36603098 PMCID: PMC9939240 DOI: 10.1126/science.abq7317] [Citation(s) in RCA: 45] [Impact Index Per Article: 45.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2022] [Accepted: 12/09/2022] [Indexed: 01/06/2023]
Abstract
The breaking of bilateral symmetry in most vertebrates is critically dependent upon the motile cilia of the embryonic left-right organizer (LRO), which generate a directional fluid flow; however, it remains unclear how this flow is sensed. Here, we demonstrated that immotile LRO cilia are mechanosensors for shear force using a methodological pipeline that combines optical tweezers, light sheet microscopy, and deep learning to permit in vivo analyses in zebrafish. Mechanical manipulation of immotile LRO cilia activated intraciliary calcium transients that required the cation channel Polycystin-2. Furthermore, mechanical force applied to LRO cilia was sufficient to rescue and reverse cardiac situs in zebrafish that lack motile cilia. Thus, LRO cilia are mechanosensitive cellular levers that convert biomechanical forces into calcium signals to instruct left-right asymmetry.
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Affiliation(s)
- Lydia Djenoune
- Cardiovascular Research Center, Cardiology Division, Department of Medicine, Massachusetts General Hospital and Harvard Medical School, Boston, MA 02129, USA
| | - Mohammed Mahamdeh
- Cardiovascular Research Center, Cardiology Division, Department of Medicine, Massachusetts General Hospital and Harvard Medical School, Boston, MA 02129, USA
| | - Thai V. Truong
- Translational Imaging Center, University of Southern California, Los Angeles, CA 90089, USA
| | - Christopher T. Nguyen
- Cardiovascular Research Center, Cardiology Division, Department of Medicine, Massachusetts General Hospital and Harvard Medical School, Boston, MA 02129, USA
- Cardiovascular Innovation Research Center, Heart, Vascular, and Thoracic Institute, Cleveland Clinic, Cleveland, OH 44195, USA
- Division of Health Science Technology, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Scott E. Fraser
- Translational Imaging Center, University of Southern California, Los Angeles, CA 90089, USA
| | - Martina Brueckner
- Departments of Pediatrics and Genetics, Yale University School of Medicine, New Haven, CT 06520, USA
| | - Jonathon Howard
- Department of Molecular Biochemistry and Biophysics, Yale University School of Medicine, New Haven, CT 06520, USA
| | - Shiaulou Yuan
- Cardiovascular Research Center, Cardiology Division, Department of Medicine, Massachusetts General Hospital and Harvard Medical School, Boston, MA 02129, USA
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3
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Adamczyk O, Baster Z, Szczypior M, Rajfur Z. Substrate Stiffness Mediates Formation of Novel Cytoskeletal Structures in Fibroblasts during Cell-Microspheres Interaction. Int J Mol Sci 2021; 22:960. [PMID: 33478069 PMCID: PMC7835802 DOI: 10.3390/ijms22020960] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2020] [Revised: 01/13/2021] [Accepted: 01/15/2021] [Indexed: 11/16/2022] Open
Abstract
It is well known that living cells interact mechanically with their microenvironment. Many basic cell functions, like migration, proliferation, gene expression, and differentiation, are influenced by external forces exerted on the cell. That is why it is extremely important to study how mechanical properties of the culture substrate influence the cellular molecular regulatory pathways. Optical microscopy is one of the most common experimental method used to visualize and study cellular processes. Confocal microscopy allows to observe changes in the 3D organization of the cytoskeleton in response to a precise mechanical stimulus applied with, for example, a bead trapped with optical tweezers. Optical tweezers-based method (OT) is a microrheological technique which employs a focused laser beam and polystyrene or latex beads to study mechanical properties of biological systems. Latex beads, functionalized with a specific protein, can interact with proteins located on the surface of the cellular membrane. Such interaction can significantly affect the cell's behavior. In this work, we demonstrate that beads alone, placed on the cell surface, significantly change the architecture of actin, microtubule, and intermediate filaments. We also show that the observed molecular response to such stimulus depends on the duration of the cell-bead interaction. Application of cytoskeletal drugs: cytochalasin D, jasplakinolide, and docetaxel, abrogates remodeling effects of the cytoskeleton. More important, when cells are plated on elastic substrates, which mimic the mechanical properties of physiological cellular environment, we observe formation of novel, "cup-like" structures formed by the microtubule cytoskeleton upon interaction with latex beads. These results provide new insights into the function of the microtubule cytoskeleton. Based on these results, we conclude that rigidity of the substrate significantly affects the cellular processes related to every component of the cytoskeleton, especially their architecture.
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Affiliation(s)
- Olga Adamczyk
- Institute of Physics, Faculty of Physics, Astronomy and Applied Computer Science, Jagiellonian University, 30-348 Kraków, Poland; (O.A.); (Z.B.); (M.S.)
| | - Zbigniew Baster
- Institute of Physics, Faculty of Physics, Astronomy and Applied Computer Science, Jagiellonian University, 30-348 Kraków, Poland; (O.A.); (Z.B.); (M.S.)
| | - Maksymilian Szczypior
- Institute of Physics, Faculty of Physics, Astronomy and Applied Computer Science, Jagiellonian University, 30-348 Kraków, Poland; (O.A.); (Z.B.); (M.S.)
| | - Zenon Rajfur
- Institute of Physics, Faculty of Physics, Astronomy and Applied Computer Science, Jagiellonian University, 30-348 Kraków, Poland; (O.A.); (Z.B.); (M.S.)
- Jagiellonian Center of Biomedical Imaging, Jagiellonian University, 30-348 Kraków, Poland
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4
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Swiatlowska P, Sanchez-Alonso JL, Wright PT, Novak P, Gorelik J. Microtubules regulate cardiomyocyte transversal Young's modulus. Proc Natl Acad Sci U S A 2020; 117:2764-2766. [PMID: 31988123 PMCID: PMC7022140 DOI: 10.1073/pnas.1917171117] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
The field of cardiomyocyte mechanobiology is gaining significant attention, due to accumulating evidence concerning the significant role of cellular mechanical effects on the integrated function of the heart. To date, the protein titin has been demonstrated as a major contributor to the cardiomyocytes Young's modulus (YM). The microtubular network represents another potential regulator of cardiac mechanics. However, the contribution of microtubules (MTs) to the membrane YM is still understudied and has not been interrogated in the context of myocardial infarction (MI) or mechanical loading and unloading. Using nanoscale mechanoscanning ion conductance microscopy, we demonstrate that MTs contribute to cardiomyocyte transverse YM in healthy and pathological states with different mechanical loading. Specifically, we show that posttranslational modifications of MTs have differing effects on cardiomyocyte YM: Acetylation provides flexibility, whereas detyrosination imparts rigidity. Further studies demonstrate that there is no correlation between the total protein amount of acetylated and detyrosinated MT. Yet, in the polymerized-only populations, an increased level of acetylation results in a decline of detyrosinated MTs in an MI model.
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Affiliation(s)
- Pamela Swiatlowska
- National Heart and Lung Institute, Imperial College London, W12 0NN London, United Kingdom
| | - Jose L Sanchez-Alonso
- National Heart and Lung Institute, Imperial College London, W12 0NN London, United Kingdom
| | - Peter T Wright
- National Heart and Lung Institute, Imperial College London, W12 0NN London, United Kingdom
| | - Pavel Novak
- School of Engineering and Materials Science, Queen Mary University of London, E1 4NS London, United Kingdom
| | - Julia Gorelik
- National Heart and Lung Institute, Imperial College London, W12 0NN London, United Kingdom;
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5
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Flaherty J, Feng Z, Peng Z, Young YN, Resnick A. Primary cilia have a length-dependent persistence length. Biomech Model Mechanobiol 2019; 19:445-460. [PMID: 31501964 PMCID: PMC7105448 DOI: 10.1007/s10237-019-01220-7] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2018] [Accepted: 08/27/2019] [Indexed: 01/25/2023]
Abstract
The fluctuating position of an optically trapped cilium tip under untreated and Taxol-treated conditions was used to characterize mechanical properties of the cilium axoneme and its basal body by combining experimental, analytical,
and computational tools. We provide, for the first time, evidence that the persistence length of a ciliary axoneme is length-dependent; longer cilia are stiffer than shorter cilia. We demonstrate that this apparent length dependence can be understood by a combination of modeling axonemal microtubules as anisotropic elastic shells and including actomyosin-driven stochastic basal body motion.
Our results also demonstrate the possibility of using observable ciliary dynamics to probe interior cytoskeletal dynamics. It is hoped that our improved characterization of cilia will result in deeper understanding of the biological function of cellular flow sensing by this organelle.
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Affiliation(s)
- Justin Flaherty
- Department of Physics, The Ohio State University, Columbus, USA
| | - Zhe Feng
- Department of Aerospace and Mechanical Engineering, University of Notre Dame, Notre Dame, IN, USA
| | - Zhangli Peng
- Department of Bioengineering, University of Illinois at Chicago, 851 S Morgan St, Chicago, IL, 60607, USA
| | - Y-N Young
- Department of Mathematical Sciences, New Jersey Institute of Technology, Newark, NJ, 07102, USA
| | - Andrew Resnick
- Department of Physics, Center for Gene Regulation in Health and Disease, Cleveland State University, Cleveland, OH, USA.
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6
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Nag S, Resnick A. Biophysics and biofluid dynamics of primary cilia: evidence for and against the flow-sensing function. Am J Physiol Renal Physiol 2017. [DOI: 10.1152/ajprenal.00172.2017] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Primary cilia have been called “the forgotten organelle” for over 20 yr. As cilia now have their own journal and several books devoted to their study, perhaps it is time to reconsider the moniker “forgotten organelle.” In fact, during the drafting of this review, 12 relevant publications have been issued; we therefore apologize in advance for any relevant work we inadvertently omitted. What purpose is yet another ciliary review? The primary goal of this review is to specifically examine the evidence for and against the hypothesized flow-sensing function of primary cilia expressed by differentiated epithelia within a kidney tubule, bringing together differing disciplines and their respective conceptual and experimental approaches. We will show that understanding the biophysics/biomechanics of primary cilia provides essential information for understanding any potential role of ciliary function in disease. We will summarize experimental and mathematical models used to characterize renal fluid flow and incident force on primary cilia and to characterize the mechanical response of cilia to an externally applied force and discuss possible ciliary-mediated cell signaling pathways triggered by flow. Throughout, we stress the importance of separating the effects of fluid shear and stretch from the action of hydrodynamic drag.
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Affiliation(s)
- Subhra Nag
- Department of Biology, Geology, and Environmental Sciences, Cleveland State University, Cleveland, Ohio
| | - Andrew Resnick
- Department of Biology, Geology, and Environmental Sciences, Cleveland State University, Cleveland, Ohio
- Department of Physics, Cleveland State University, Cleveland, Ohio; and
- Center for Gene Regulation in Health and Disease, Cleveland State University, Cleveland, Ohio
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7
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Abstract
Although solitary or sensory cilia are present in most cells of the body and their existence has been known since the sixties, very little is known about their functions. One suspected function is fluid flow sensing- physical bending of cilia produces an influx of Ca++, which can then result in a variety of activated signaling pathways. Defective cilia and ciliary-associated proteins have been shown to result in cystic diseases. Autosomal Dominant Polycystic Kidney Disease (ADPKD) is a progressive disease, typically appearing in the 5th decade of life and is one of the most common monogenetic inherited human diseases, affecting approximately 600,000 people in the United States. Because the mechanical properties of cilia impact their response to applied flow, we asked how the stiffness of cilia can be controlled pharmacologically. We performed an experiment subjecting cilia to Taxol (a microtubule stabilizer) and CoCl2 (a HIF stabilizer to model hypoxia). Madin-Darby Canine Kidney (MDCK) cells were selected as our model system. After incubation with a selected pharmacological agent, cilia were optically trapped and the bending modulus measured. We found that HIF stabilization significantly weakens cilia. These results illustrate a method to alter the mechanical properties of primary cilia and potentially alter the flow sensing properties of cilia.
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Affiliation(s)
- Andrew Resnick
- Department of Physics, Cleveland State University, Cleveland, Ohio, United States of America.,Center for Gene Regulation in Health and Disease, Cleveland State University, Cleveland, Ohio, United States of America
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8
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Turdalieva A, Solandt J, Shambetova N, Xu H, Blom H, Brismar H, Zelenina M, Fu Y. Bioelectric and Morphological Response of Liquid-Covered Human Airway Epithelial Calu-3 Cell Monolayer to Periodic Deposition of Colloidal 3-Mercaptopropionic-Acid Coated CdSe-CdS/ZnS Core-Multishell Quantum Dots. PLoS One 2016; 11:e0149915. [PMID: 26913754 PMCID: PMC4767322 DOI: 10.1371/journal.pone.0149915] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2015] [Accepted: 02/05/2016] [Indexed: 12/15/2022] Open
Abstract
Lung epithelial cells are extensively exposed to nanoparticles present in the modern urban environment. Nanoparticles, including colloidal quantum dots (QDs), are also considered to be potentially useful carriers for the delivery of drugs into the body. It is therefore important to understand the ways of distribution and the effects of the various types of nanoparticles in the lung epithelium. We use a model system of liquid-covered human airway epithelial Calu-3 cell cultures to study the immediate and long-term effects of repeated deposition of colloidal 3-mercaptopropionic-acid coated CdSe-CdS/ZnS core-multishell QDs on the lung epithelial cell surface. By live confocal microscope imaging and by QD fluorescence measurements we show that the QD permeation through the mature epithelial monolayers is very limited. At the time of QD deposition, the transepithelial electrical resistance (TEER) of the epithelial monolayers transiently decreased, with the decrement being proportional to the QD dose. Repeated QD deposition, once every six days for two months, lead to accumulation of only small amounts of the QDs in the cell monolayer. However, it did not induce any noticeable changes in the long-term TEER and the molecular morphology of the cells. The colloidal 3-mercaptopropionic-acid coated CdSe-CdS/ZnS core-multishell QDs could therefore be potentially used for the delivery of drugs intended for the surface of the lung epithelia during limited treatment periods.
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Affiliation(s)
- Aizat Turdalieva
- Science for Life Laboratory, Department of Applied Physics, Royal Institute of Technology, SE-106 91 Stockholm, Sweden
| | | | - Nestan Shambetova
- Science for Life Laboratory, Department of Applied Physics, Royal Institute of Technology, SE-106 91 Stockholm, Sweden
| | - Hao Xu
- Science for Life Laboratory, Department of Applied Physics, Royal Institute of Technology, SE-106 91 Stockholm, Sweden
| | - Hans Blom
- Advanced Light Microscopy facility, Science for Life Laboratory, Solna, Sweden
| | - Hjalmar Brismar
- Science for Life Laboratory, Department of Applied Physics, Royal Institute of Technology, SE-106 91 Stockholm, Sweden
| | - Marina Zelenina
- Science for Life Laboratory, Department of Applied Physics, Royal Institute of Technology, SE-106 91 Stockholm, Sweden
| | - Ying Fu
- Science for Life Laboratory, Department of Applied Physics, Royal Institute of Technology, SE-106 91 Stockholm, Sweden
- * E-mail:
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9
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Bernardeschi I, Greco F, Ciofani G, Marino A, Mattoli V, Mazzolai B, Beccai L. A soft, stretchable and conductive biointerface for cell mechanobiology. Biomed Microdevices 2016; 17:46. [PMID: 25797705 DOI: 10.1007/s10544-015-9950-0] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
In mechanobiology the study of cell response to mechanical stimuli is fundamental, and the involved processes (i.e., mechanotransduction) need to be investigated by interfacing (mechanically and electrically) with the cells in dynamic and non-invasive natural-like conditions. In this work, we present a novel soft, stretchable and conductive biointerface that allows both cell mechanical stimulation and dynamic impedance recording. The biointerface stretchability and conductivity, jointly to the biocompatibility and transparency needed to perform cell culture studies, were obtained by exploiting the formation of wrinkles on the surface of a 90 nm thick conductive layer of poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) on a pre-stretched 130 μm thick poly(dimethylsiloxane) (PDMS) substrate. Cell adhesion and proliferation of SH-SY5Y human neuroblastoma cells were evaluated, and cell differentiation on the corrugated surface was assessed. We demonstrate how the biointerface remains conductive when applying uniaxial strain up to 10%, and when cell culturing is performed. Finally, a reduction of about 30% of the relative impedance variation signal was measured, with respect to the control, as a result of the mechanical stimulation of cells.
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Affiliation(s)
- Irene Bernardeschi
- Center for Micro-BioRobotics, Istituto Italiano di Tecnologia, Viale Rinaldo Piaggio 34, 56025, Pontedera, PI, Italy
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10
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Raghavan V, Weisz OA. Discerning the role of mechanosensors in regulating proximal tubule function. Am J Physiol Renal Physiol 2015; 310:F1-5. [PMID: 26662200 DOI: 10.1152/ajprenal.00373.2015] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
All cells in the body experience external mechanical forces such as shear stress and stretch. These forces are sensed by specialized structures in the cell known as mechanosensors. Cells lining the proximal tubule (PT) of the kidney are continuously exposed to variations in flow rates of the glomerular ultrafiltrate, which manifest as changes in axial shear stress and radial stretch. Studies suggest that these cells respond acutely to variations in flow by modulating their ion transport and endocytic functions to maintain glomerulotubular balance. Conceptually, changes in the axial shear stress in the PT could be sensed by three known structures, namely, the microvilli, the glycocalyx, and primary cilia. The orthogonal component of the force produced by flow exhibits as radial stretch and can cause expansion of the tubule. Forces of stretch are transduced by integrins, by stretch-activated channels, and by cell-cell contacts. This review summarizes our current understanding of flow sensing in PT epithelia, discusses challenges in dissecting the role of individual flow sensors in the mechanosensitive responses, and identifies potential areas of opportunity for new study.
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Affiliation(s)
- Venkatesan Raghavan
- Renal-Electrolyte Division, Department of Medicine, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania
| | - Ora A Weisz
- Renal-Electrolyte Division, Department of Medicine, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania
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11
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Narciso C, Wu Q, Brodskiy P, Garston G, Baker R, Fletcher A, Zartman J. Patterning of wound-induced intercellular Ca(2+) flashes in a developing epithelium. Phys Biol 2015; 12:056005. [PMID: 26331891 DOI: 10.1088/1478-3975/12/5/056005] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Differential mechanical force distributions are increasingly recognized to provide important feedback into the control of an organ's final size and shape. As a second messenger that integrates and relays mechanical information to the cell, calcium ions (Ca(2+)) are a prime candidate for providing important information on both the overall mechanical state of the tissue and resulting behavior at the individual-cell level during development. Still, how the spatiotemporal properties of Ca(2+) transients reflect the underlying mechanical characteristics of tissues is still poorly understood. Here we use an established model system of an epithelial tissue, the Drosophila wing imaginal disc, to investigate how tissue properties impact the propagation of Ca(2+) transients induced by laser ablation. The resulting intercellular Ca(2+) flash is found to be mediated by inositol 1,4,5-trisphosphate and depends on gap junction communication. Further, we find that intercellular Ca(2+) transients show spatially non-uniform characteristics across the proximal-distal axis of the larval wing imaginal disc, which exhibit a gradient in cell size and anisotropy. A computational model of Ca(2+) transients is employed to identify the principle factors explaining the spatiotemporal patterning dynamics of intercellular Ca(2+) flashes. The relative Ca(2+) flash anisotropy is principally explained by local cell shape anisotropy. Further, Ca(2+) velocities are relatively uniform throughout the wing disc, irrespective of cell size or anisotropy. This can be explained by the opposing effects of cell diameter and cell elongation on intercellular Ca(2+) propagation. Thus, intercellular Ca(2+) transients follow lines of mechanical tension at velocities that are largely independent of tissue heterogeneity and reflect the mechanical state of the underlying tissue.
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Affiliation(s)
- Cody Narciso
- Department of Chemical and Biomolecular Engineering, University of Notre Dame, 182 Fitzpatrick Hall, Notre Dame, IN 46556, USA
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12
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Praetorius HA. The primary cilium as sensor of fluid flow: new building blocks to the model. A review in the theme: cell signaling: proteins, pathways and mechanisms. Am J Physiol Cell Physiol 2014; 308:C198-208. [PMID: 25428884 DOI: 10.1152/ajpcell.00336.2014] [Citation(s) in RCA: 62] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
The primary cilium is an extraordinary organelle. For many years, it had the full attention of only a few dedicated scientists fascinated by its uniqueness. Unexpectedly, after decades of obscurity, it has moved very quickly into the limelight with the increasing evidence of its central role in the many genetic variations that lead to what are now known as ciliopathies. These studies implicated unique biological functions of the primary cilium, which are not completely straightforward. In parallel, and initially completely unrelated to the ciliopathies, the primary cilium was characterized functionally as an organelle that makes cells more susceptible to changes in fluid flow. Thus the primary cilium was suggested to function as a flow-sensing device. This characterization has been substantiated for many epithelial cell types over the years. Nevertheless, part of the central mechanism of signal transduction has not been explained, largely because of the substantial technical challenges of working with this delicate organelle. The current review considers the recent advances that allow us to fill some of the holes in the model of signal transduction in cilium-mediated responses to fluid flow and to pursue the physiological implications of this peculiar organelle.
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Affiliation(s)
- Helle A Praetorius
- Department of Biomedicine-Physiology, Aarhus University, Aarhus, Denmark
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13
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Weinbaum S, Duan Y, Thi MM, You L. An Integrative Review of Mechanotransduction in Endothelial, Epithelial (Renal) and Dendritic Cells (Osteocytes). Cell Mol Bioeng 2011; 4:510-537. [PMID: 23976901 DOI: 10.1007/s12195-011-0179-6] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
In this review we will examine from a biomechanical and ultrastructural viewpoint how the cytoskeletal specialization of three basic cell types, endothelial cells (ECs), epithelial cells (renal tubule) and dendritic cells (osteocytes), enables the mechano-sensing of fluid flow in both their native in vivo environment and in culture, and the downstream signaling that is initiated at the molecular level in response to fluid flow. These cellular responses will be discussed in terms of basic mysteries and paradoxes encountered by each cell type. In ECs fluid shear stress (FSS) is nearly entirely attenuated by the endothelial glycocalyx that covers their apical membrane and yet FSS is communicated to both intracellular and junctional molecular components in activating a wide variety of signaling pathways. The same is true in proximal tubule (PT) cells where a dense brush border of microvilli covers the apical surface and the flow at the apical membrane is negligible. A four decade old unexplained mystery is the ability of PT epithelia to reliably reabsorb 60% of the flow entering the tubule regardless of the glomerular filtration rate. In the cortical collecting duct (CCD) the flow rates are so low that a special sensing apparatus, a primary cilia is needed to detect very small variations in tubular flow. In bone it has been a century old mystery as to how osteocytes embedded in a stiff mineralized tissue are able to sense miniscule whole tissue strains that are far smaller than the cellular level strains required to activate osteocytes in vitro.
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Affiliation(s)
- Sheldon Weinbaum
- Department of Biomedical Engineering, The City College of the City University of New York, New York, NY 10031, USA
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14
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Holle AW, Engler AJ. More than a feeling: discovering, understanding, and influencing mechanosensing pathways. Curr Opin Biotechnol 2011; 22:648-54. [PMID: 21536426 DOI: 10.1016/j.copbio.2011.04.007] [Citation(s) in RCA: 98] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2011] [Accepted: 04/01/2011] [Indexed: 11/30/2022]
Abstract
The ability of cells to extract biophysical information from their extracellular environment and convert it to biochemical signals is known as mechanotransduction. Here we detail three passive, 'inside-out' mechanotransduction mechanisms with an emphasis on the mechanosensing pathways involved in creating these signal: Rho/ROCK, stretch-activated channels, and 'Molecular Strain Gauges.' We also examine how molecular tools have been used to perturb these pathways to better understand their interconnectivity. However, perturbing pathways may have unintended confounding effects, which must also be addressed. By discovering and understanding mechanosensitive pathways, the ability to influence them for clinical applications increases.
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Affiliation(s)
- Andrew W Holle
- Department of Bioengineering, University of California, San Diego, La Jolla, CA 92093, USA
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15
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Reiner JE, Kishore RB, Levin BC, Albanetti T, Boire N, Knipe A, Helmerson K, Deckman KH. Detection of heteroplasmic mitochondrial DNA in single mitochondria. PLoS One 2010; 5:e14359. [PMID: 21179558 PMCID: PMC3002942 DOI: 10.1371/journal.pone.0014359] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2010] [Accepted: 10/27/2010] [Indexed: 01/11/2023] Open
Abstract
Background Mitochondrial DNA (mtDNA) genome mutations can lead to energy and respiratory-related disorders like myoclonic epilepsy with ragged red fiber disease (MERRF), mitochondrial myopathy, encephalopathy, lactic acidosis and stroke (MELAS) syndrome, and Leber's hereditary optic neuropathy (LHON). It is not well understood what effect the distribution of mutated mtDNA throughout the mitochondrial matrix has on the development of mitochondrial-based disorders. Insight into this complex sub-cellular heterogeneity may further our understanding of the development of mitochondria-related diseases. Methodology This work describes a method for isolating individual mitochondria from single cells and performing molecular analysis on that single mitochondrion's DNA. An optical tweezer extracts a single mitochondrion from a lysed human HL-60 cell. Then a micron-sized femtopipette tip captures the mitochondrion for subsequent analysis. Multiple rounds of conventional DNA amplification and standard sequencing methods enable the detection of a heteroplasmic mixture in the mtDNA from a single mitochondrion. Significance Molecular analysis of mtDNA from the individually extracted mitochondrion demonstrates that a heteroplasmy is present in single mitochondria at various ratios consistent with the 50/50 heteroplasmy ratio found in single cells that contain multiple mitochondria.
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Affiliation(s)
- Joseph E Reiner
- Physical Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, Maryland, United States of America.
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