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Satarić MV, Nemeš T. On the role of calcium diffusion and its rapid buffering in intraflagellar signaling. EUROPEAN BIOPHYSICS JOURNAL : EBJ 2023; 52:705-720. [PMID: 37851099 DOI: 10.1007/s00249-023-01685-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/02/2023] [Revised: 09/13/2023] [Accepted: 09/23/2023] [Indexed: 10/19/2023]
Abstract
We have considered the realistic mechanism of rapid Ca2+ (calcium ion) buffering within the wave of calcium ions progressing along the flagellar axoneme. This buffering is an essential part of the Ca2+ signaling pathway aimed at controlling the bending dynamics of flagella. It is primarily achieved by the mobile region of calmodulin molecules and by stationary calaxin, as well as by the part of calmodulin bound to calcium/calmodulin-dependent kinase II and kinase C. We derived and elaborated a model of Ca2+ diffusion within a signaling wave in the presence of these molecules which rapidly buffer Ca2+. This approach has led to a single nonlinear transport equation for the Ca2+ wave that contains the effects brought about by both as necessary buffers for signaling. The presence of mobile buffer calmodulin gives rise to a transport equation that is not strictly diffusive but also exhibits a sink-like effect. We solved straightforwardly the final transport equation in an analytical framework and obtained the implied function of calcium concentration. The effective diffusion coefficient depends on local Ca2+ concentration. It is plausible that these buffers' presence can impact Ca2+ wave speed and shape, which are essential for decoding Ca2+ signaling in flagella. We present the solution of the transport equation for a few specified cases with physiologically reasonable sets of parameters involved.
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Affiliation(s)
- M V Satarić
- Serbian Academy of Science and Arts, Belgrade, Serbia
| | - T Nemeš
- Faculty of Technical Sciences, University of Novi Sad, Novi Sad, Serbia.
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2
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Satarić MV, Nemeš T, Zdravković S. Calcium messages in flagella are faster than messenger particles. Biosystems 2023; 232:105003. [PMID: 37625514 DOI: 10.1016/j.biosystems.2023.105003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2023] [Revised: 08/17/2023] [Accepted: 08/17/2023] [Indexed: 08/27/2023]
Abstract
Calcium is one of the most versatile messengers for intracellular signaling. In the case of cilia and flagella calcium has the central role in transfer of communications between extracellular stimuli and intracellular formation of frequency modulated signal and their deciphering by target proteins. In this paper, the diffusion of fluorescently or otherwise tagged and un-tagged Ca2+ particles is analyzed by solving the system of pertaining reaction-diffusion equations. We used Fourier transform tools to get asymptotic eigenfunctions for tagged (un-tagged) free and buffered Ca2+ ions. We made some numerical estimations for diffusion coefficients corroborating the fact that messages diffuse faster than Ca2+ messengers. From the best of our knowledge, this is the first time that Ca2+ signaling in living cells is biophysically elaborated within the framework of model presented here. We suggest the experimental assay on the basis of radioactive Ca2+ as tagged probe.
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Affiliation(s)
| | - Tomas Nemeš
- Faculty of Technical Sciences, Novi Sad, Serbia.
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3
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Palicha KA, Loganathan P, Sudha V, Harinipriya S. Monte Carlo simulation and experimental validation of plant microtubules cathode in biodegradable battery. Sci Rep 2023; 13:10393. [PMID: 37369685 DOI: 10.1038/s41598-023-36902-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2023] [Accepted: 06/12/2023] [Indexed: 06/29/2023] Open
Abstract
For the first time, electrochemical methods are utilized to study the response of tubulin monomers (extracted from plant source such as Green Peas: Arachis Hypogea) towards charge perturbations in the form of conductivity, conformational changes via self-assembly and adsorption on Au surface. The obtained dimerization and surface adsorption energetics of the tubulins from Cyclic Voltammetry agree well with the literature value of 6.9 and 14.9 kCal/mol for lateral and longitudinal bond formation energy respectively. In addition to the effects of charge perturbations on change in structure, ionic and electronic conductivity of tubulin with increasing load are investigated and found to be 1.25 Sm-1 and 2.89 mSm-1 respectively. The electronic conductivity is 1.93 times higher than the literature value of 1.5 mSm-1, demonstrating the fact that the microtubules (dimer of tubulins, MTs) from plant source can be used as a semiconductor electrode material in energy conversion and storage applications. Thus, motivated by the Monte Carlo simulation and electrochemical results the MTs extracted from plant source are used as cathode material for energy storage device such as Bio-battery and the Galvanostatic Charge/Discharge studies are carried out in coin cell configuration. The configuration of the bio-battery cell is as follows: Al/CB//PP-1M KCl//MTs/SS; where SS and Al are used as current collectors for cathode and anode respectively, Polypropylene (PP) membrane soaked in 1M KCl as electrolyte and Carbon Black (CB) is the anode material. Another configuration of the cell would be replacement of CB by biopolymer such as ethyl cellulose anode (Al/EC/PP-1M KCl/MTs/SS).
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Affiliation(s)
- Kaushik A Palicha
- Research and Development Center, Ram Charan Co Pvt Ltd - Entity1, Chennai, Tamilnadu, 600 002, India
| | - Pavithra Loganathan
- Department of Physics and Nanotechnology, SRMIST, Kattankulathur, Chennai, Tamilnadu, 603203, India
| | - V Sudha
- Department of Chemistry, SRMIST, Kattankulathur, Chennai, Tamilnadu, 603203, India.
| | - S Harinipriya
- Research and Development Center, Ram Charan Co Pvt Ltd - Entity1, Chennai, Tamilnadu, 600 002, India.
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4
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Microtubules as a potential platform for energy transfer in biological systems: a target for implementing individualized, dynamic variability patterns to improve organ function. Mol Cell Biochem 2023; 478:375-392. [PMID: 35829870 DOI: 10.1007/s11010-022-04513-1] [Citation(s) in RCA: 18] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2022] [Accepted: 06/24/2022] [Indexed: 02/07/2023]
Abstract
Variability characterizes the complexity of biological systems and is essential for their function. Microtubules (MTs) play a role in structural integrity, cell motility, material transport, and force generation during mitosis, and dynamic instability exemplifies the variability in the proper function of MTs. MTs are a platform for energy transfer in cells. The dynamic instability of MTs manifests itself by the coexistence of growth and shortening, or polymerization and depolymerization. It results from a balance between attractive and repulsive forces between tubulin dimers. The paper reviews the current data on MTs and their potential roles as energy-transfer cellular structures and presents how variability can improve the function of biological systems in an individualized manner. The paper presents the option for targeting MTs to trigger dynamic improvement in cell plasticity, regulate energy transfer, and possibly control quantum effects in biological systems. The described system quantifies MT-dependent variability patterns combined with additional personalized signatures to improve organ function in a subject-tailored manner. The platform can regulate the use of MT-targeting drugs to improve the response to chronic therapies. Ongoing trials test the effects of this platform on various disorders.
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5
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Brain Microtubule Electrical Oscillations-Empirical Mode Decomposition Analysis. Cell Mol Neurobiol 2022:10.1007/s10571-022-01290-9. [PMID: 36207654 DOI: 10.1007/s10571-022-01290-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2022] [Accepted: 09/24/2022] [Indexed: 11/03/2022]
Abstract
Microtubules (MTs) are essential cytoskeletal polymers of eukaryote cells implicated in various cell functions, including cell division, cargo transfer, and cell signaling. MTs also are highly charged polymers that generate electrical oscillations that may underlie their ability to act as nonlinear transmission lines. However, the oscillatory composition and time-frequency differences of the MT electrical oscillations have not been identified. Here, we applied the Empirical Mode Decomposition (EMD) to bovine brain MT sheet recordings to determine the number and fundamental frequencies of the Intrinsic Modes Functions (IMF) and evaluate their energetic contribution to the electrical signal. As previously reported, raw signals were obtained from cow brain MTs (Cantero et al. Sci Rep 6:27143, 2016), sampled, filtered, and subjected to signal decomposition from representative experiments. Filtered signals (200 Hz) allowed us to identify either six or seven IMFs. The reconstructed tracings faithfully resembled the original signals, with identifiable frequency peaks. To extend the analysis to obtain time-frequency information and the energy implicated in each IMF, we applied the Hilbert-Huang Transform (HHT) and the Continuous Wavelet Transform (CWT) to the same samples. The analyses disclosed the presence of more fundamental frequency peaks than initially reported and evidenced the advantages and disadvantages of each transform. The study indicates that the EMD is a robust approach to quantifying signal decomposition of brain MT oscillations and suggests novel similarities with human brain wave electroencephalogram (EEG) recordings. The evidence points to the potentially fundamental role of MT oscillations in brain electrical activity.
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6
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Joshi FM, Viar GA, Pigino G, Drechsler H, Diez S. Fabrication of High Aspect Ratio Gold Nanowires within the Microtubule Lumen. NANO LETTERS 2022; 22:3659-3667. [PMID: 35446032 DOI: 10.1021/acs.nanolett.2c00255] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Gold nanowires have great potential use as interconnects in electronic, photonic, and optoelectronic devices. To date, there are various fabrication strategies for gold nanowires, each one associated with particular drawbacks as they utilize high temperatures, toxic chemicals, or expensive compounds to produce nanowires of suboptimal quality. Inspired by nanowire fabrication strategies that used higher-order biopolymer structures as molds for electroless deposition of gold, we here report a strategy for the growth of gold nanowires from seed nanoparticles within the lumen of microtubules. Luminal targeting of seed particles occurs through covalently linked Fab fragments of an antibody recognizing the acetylated lysine 40 on the luminal side of α-tubulin. Gold nanowires grown by electroless deposition within the microtubule lumen exhibit a homogeneous morphology and high aspect ratios with a mean diameter of 20 nm. Our approach is fast, simple, and inexpensive and does not require toxic chemicals or other harsh conditions.
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Affiliation(s)
- Foram M Joshi
- B CUBE - Center for Molecular Bioengineering, Technische Universität Dresden, 01307 Dresden, Germany
| | - Gonzalo Alvarez Viar
- Max Planck Institute of Molecular Cell Biology and Genetics, 01307 Dresden, Germany
| | - Gaia Pigino
- Max Planck Institute of Molecular Cell Biology and Genetics, 01307 Dresden, Germany
- Human Technopole, 20157 Milan, Italy
| | - Hauke Drechsler
- B CUBE - Center for Molecular Bioengineering, Technische Universität Dresden, 01307 Dresden, Germany
| | - Stefan Diez
- B CUBE - Center for Molecular Bioengineering, Technische Universität Dresden, 01307 Dresden, Germany
- Max Planck Institute of Molecular Cell Biology and Genetics, 01307 Dresden, Germany
- Cluster of Excellence Physics of Life, Technische Universität Dresden, 01307 Dresden, Germany
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7
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Nasedkin A, Ermilova I, Swenson J. Atomistic molecular dynamics simulations of tubulin heterodimers explain the motion of a microtubule. EUROPEAN BIOPHYSICS JOURNAL : EBJ 2021; 50:927-940. [PMID: 34215900 PMCID: PMC8448678 DOI: 10.1007/s00249-021-01553-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/18/2021] [Revised: 05/24/2021] [Accepted: 06/07/2021] [Indexed: 06/13/2023]
Abstract
Microtubules are essential parts of the cytoskeleton that are built by polymerization of tubulin heterodimers into a hollow tube. Regardless that their structures and functions have been comprehensively investigated in a modern soft matter, it is unclear how properties of tubulin heterodimer influence and promote the self-assembly. A detailed knowledge of such structural mechanisms would be helpful in drug design against neurodegenerative diseases, cancer, diabetes etc. In this work atomistic molecular dynamics simulations were used to investigate the fundamental dynamics of tubulin heterodimers in a sheet and a short microtubule utilizing well-equilibrated structures. The breathing motions of the tubulin heterodimers during assembly show that the movement at the lateral interface between heterodimers (wobbling) dominates in the lattice. The simulations of the protofilament curvature agrees well with recently published experimental data, showing curved protofilaments at polymerization of the microtubule plus end. The tubulin heterodimers exposed at the microtubule minus end were less curved and displayed altered interactions at the site of sheet closure around the outmost heterodimers, which may slow heterodimer binding and polymerization, providing a potential explanation for the limited dynamics observed at the minus end.
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Affiliation(s)
- Alexandr Nasedkin
- Department of Physics, Chalmers University of Technology, SE 41296 Göteborg, Sweden
| | - Inna Ermilova
- Department of Physics, Chalmers University of Technology, SE 41296 Göteborg, Sweden
| | - Jan Swenson
- Department of Physics, Chalmers University of Technology, SE 41296 Göteborg, Sweden
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8
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Calcium signal transmission by axonemal microtubules as an optimized information pathway in cilia and flagella. J Bioenerg Biomembr 2021; 53:633-641. [PMID: 34537954 DOI: 10.1007/s10863-021-09920-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2021] [Accepted: 09/07/2021] [Indexed: 10/20/2022]
Abstract
Calcium plays a key role in signal transduction in eukaryotic cells. Besides controlling local functions of cells calcium ions are responsible for the generation of global signals such as waves and spikes. Pulsatile increases of calcium concentrations are generally considered to have a much higher fidelity of information transfer than simple tonic changes, since they are much less prone to noisy fluctuations. In that respect, it was clearly revealed that Ca2+ has very crucial involvement in many signaling pathways in cilia and flagella. We earlier established a model in which axonemal microtubules exhibit the features of nonlinear polyelectrolitic electric transmissions lines for efficient transport of cations, primarily Ca2+. These microtubules guide accumulated "ionic clods" which serve as the pulsatile signals aimed to regulate pertaining motor proteins, dyneins and kinesis. We here consider such Ca2+ signals in axoneme in the context of Shannon's and Fisher's information theories. It appears that the fast drift of these "ionic clouds" represents the optimized calcium signaling for control of "flagellary beats" as well as intraflagellary transport of proteins essential for the construction, elongation and maintenance of eukaryotic cilia and flagella themselves.
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9
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Vissol-Gaudin E, Pearson C, Groves C, Zeze DA, Cantiello HF, Cantero MDR, Petty MC. Electrical behaviour and evolutionary computation in thin films of bovine brain microtubules. Sci Rep 2021; 11:10776. [PMID: 34031499 PMCID: PMC8144580 DOI: 10.1038/s41598-021-90260-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2021] [Accepted: 04/12/2021] [Indexed: 11/10/2022] Open
Abstract
We report on the electrical behaviour of thin films of bovine brain microtubules (MTs). For samples in both their dried and hydrated states, the measured currents reveal a power law dependence on the applied DC voltage. We attribute this to the injection of space-charge from the metallic electrode(s). The MTs are thought to form a complex electrical network, which can be manipulated with an applied voltage. This feature has been exploited to undertake some experiments on the use of the MT mesh as a medium for computation. We show that it is possible to evolve MT films into binary classifiers following an evolution in materio approach. The accuracy of the system is, on average, similar to that of early carbon nanotube classifiers developed using the same methodology.
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Affiliation(s)
| | - Chris Pearson
- Department of Engineering, Durham University, South Road, Durham, DH1 3LE, UK
| | - Chris Groves
- Department of Engineering, Durham University, South Road, Durham, DH1 3LE, UK
| | - Dagou A Zeze
- Department of Engineering, Durham University, South Road, Durham, DH1 3LE, UK
| | - Horacio F Cantiello
- Laboratorio de Canales Iónicos, Instituto Multidisciplinario de Salud, Tecnología Y Desarrollo (IMSaTeD, CONICET-UNSE), Villa El Zanjón, 4206, Santiago del Estero, Argentina
| | - María Del Rocio Cantero
- Laboratorio de Canales Iónicos, Instituto Multidisciplinario de Salud, Tecnología Y Desarrollo (IMSaTeD, CONICET-UNSE), Villa El Zanjón, 4206, Santiago del Estero, Argentina
| | - Michael C Petty
- Department of Engineering, Durham University, South Road, Durham, DH1 3LE, UK.
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10
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Eakins BB, Patel SD, Kalra AP, Rezania V, Shankar K, Tuszynski JA. Modeling Microtubule Counterion Distributions and Conductivity Using the Poisson-Boltzmann Equation. Front Mol Biosci 2021; 8:650757. [PMID: 33842549 PMCID: PMC8027483 DOI: 10.3389/fmolb.2021.650757] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2021] [Accepted: 02/19/2021] [Indexed: 12/16/2022] Open
Abstract
Microtubules are highly negatively charged proteins which have been shown to behave as bio-nanowires capable of conducting ionic currents. The electrical characteristics of microtubules are highly complicated and have been the subject of previous work; however, the impact of the ionic concentration of the buffer solution on microtubule electrical properties has often been overlooked. In this work we use the non-linear Poisson Boltzmann equation, modified to account for a variable permittivity and a Stern Layer, to calculate counterion concentration profiles as a function of the ionic concentration of the buffer. We find that for low-concentration buffers ([KCl] from 10 μM to 10 mM) the counterion concentration is largely independent of the buffer's ionic concentration, but for physiological-concentration buffers ([KCl] from 100 to 500 mM) the counterion concentration varies dramatically with changes in the buffer's ionic concentration. We then calculate the conductivity of microtubule-counterion complexes, which are found to be more conductive than the buffer when the buffer's ionic concentrations is less than ≈100 mM and less conductive otherwise. These results demonstrate the importance of accounting for the ionic concentration of the buffer when analyzing microtubule electrical properties both under laboratory and physiological conditions. We conclude by calculating the basic electrical parameters of microtubules over a range of ionic buffer concentrations applicable to nanodevice and medical applications.
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Affiliation(s)
- Boden B Eakins
- Department of Electrical and Computer Engineering, University of Alberta, Edmonton, AB, Canada
| | - Sahil D Patel
- Department of Electrical and Computer Engineering, University of California, Santa Barbara, Santa Barbara, CA, United States
| | - Aarat P Kalra
- Department of Chemistry, Princeton University, Princeton, NJ, United States
| | - Vahid Rezania
- Department of Physical Sciences, MacEwan University, Edmonton, AB, Canada
| | - Karthik Shankar
- Department of Electrical and Computer Engineering, University of Alberta, Edmonton, AB, Canada
| | - Jack A Tuszynski
- Department of Physics, University of Alberta, Edmonton, AB, Canada.,Department of Mechanical and Aerospace Engineering, Politecnico di Torino, Turin, Italy.,Department of Oncology, University of Alberta, Edmonton, AB, Canada
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11
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Kalra AP, Eakins BB, Patel SD, Ciniero G, Rezania V, Shankar K, Tuszynski JA. All Wired Up: An Exploration of the Electrical Properties of Microtubules and Tubulin. ACS NANO 2020; 14:16301-16320. [PMID: 33213135 DOI: 10.1021/acsnano.0c06945] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Microtubules are hollow, cylindrical polymers of the protein α, β tubulin, that interact mechanochemically with a variety of macromolecules. Due to their mechanically robust nature, microtubules have gained attention as tracks for precisely directed transport of nanomaterials within lab-on-a-chip devices. Primarily due to the unusually negative tail-like C-termini of tubulin, recent work demonstrates that these biopolymers are also involved in a broad spectrum of intracellular electrical signaling. Microtubules and their electrostatic properties are discussed in this Review, followed by an evaluation of how these biopolymers respond mechanically to electrical stimuli, through microtubule migration, electrorotation and C-termini conformation changes. Literature focusing on how microtubules act as nanowires capable of intracellular ionic transport, charge storage, and ionic signal amplification is reviewed, illustrating how these biopolymers attenuate ionic movement in response to electrical stimuli. The Review ends with a discussion on the important questions, challenges, and future opportunities for intracellular microtubule-based electrical signaling.
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Affiliation(s)
- Aarat P Kalra
- Department of Physics, University of Alberta, 11335 Saskatchewan Dr NW, Edmonton, Alberta T6G 2M9, Canada
| | - Boden B Eakins
- Department of Electrical and Computer Engineering, University of Alberta, 9107-116 St, Edmonton, Alberta T6G 2 V4, Canada
| | - Sahil D Patel
- Department of Electrical and Computer Engineering, University of Alberta, 9107-116 St, Edmonton, Alberta T6G 2 V4, Canada
| | - Gloria Ciniero
- Department of Mechanical and Aerospace Engineering (DIMEAS), Politecnico di Torino, Torino 10129, Italy
| | - Vahid Rezania
- Department of Physical Sciences, MacEwan University, Edmonton, Alberta T5J 4S2, Canada
| | - Karthik Shankar
- Department of Electrical and Computer Engineering, University of Alberta, 9107-116 St, Edmonton, Alberta T6G 2 V4, Canada
| | - Jack A Tuszynski
- Department of Physics, University of Alberta, 11335 Saskatchewan Dr NW, Edmonton, Alberta T6G 2M9, Canada
- Department of Mechanical and Aerospace Engineering (DIMEAS), Politecnico di Torino, Torino 10129, Italy
- Department of Oncology, University of Alberta, Edmonton, Alberta T6G 1Z2, Canada
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12
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Calcium signaling modulates the dynamics of cilia and flagella. EUROPEAN BIOPHYSICS JOURNAL: EBJ 2020; 49:619-631. [PMID: 33105487 DOI: 10.1007/s00249-020-01471-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/12/2020] [Accepted: 10/12/2020] [Indexed: 10/23/2022]
Abstract
To adapt to changing environments cells must signal and signaling requires messengers whose concentration varies with time in space. We here consider the messenger role of calcium ions implicated in regulation of the wave-like bending dynamics of cilia and flagella. The emphasis is on microtubules as polyelectrolytes serving as transmission lines for the flow of Ca2+ signals in the axoneme. This signaling is superimposed with a geometric clutch mechanism for the regulation of flagella bending dynamics and our modeling produces results in agreement with experimental data.
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13
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Satarić MV, Nemeš T, Satarić B, Sekulić D, Zdravković S. Calcium ions tune the beats of cilia and flagella. Biosystems 2020; 196:104172. [DOI: 10.1016/j.biosystems.2020.104172] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2020] [Revised: 05/13/2020] [Accepted: 05/13/2020] [Indexed: 01/19/2023]
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14
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Investigation of the Electrical Properties of Microtubule Ensembles under Cell-Like Conditions. NANOMATERIALS 2020; 10:nano10020265. [PMID: 32033331 PMCID: PMC7075204 DOI: 10.3390/nano10020265] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/04/2019] [Revised: 01/28/2020] [Accepted: 01/29/2020] [Indexed: 01/01/2023]
Abstract
Microtubules are hollow cylindrical polymers composed of the highly negatively-charged (~23e), high dipole moment (1750 D) protein α, β- tubulin. While the roles of microtubules in chromosomal segregation, macromolecular transport, and cell migration are relatively well-understood, studies on the electrical properties of microtubules have only recently gained strong interest. Here, we show that while microtubules at physiological concentrations increase solution capacitance, free tubulin has no appreciable effect. Further, we observed a decrease in electrical resistance of solution, with charge transport peaking between 20-60 Hz in the presence of microtubules, consistent with recent findings that microtubules exhibit electric oscillations at such low frequencies. We were able to quantify the capacitance and resistance of the microtubules (MT) network at physiological tubulin concentrations to be 1.27 × 10-5 F and 9.74 × 104 Ω. Our results show that in addition to macromolecular transport, microtubules also act as charge storage devices through counterionic condensation across a broad frequency spectrum. We conclude with a hypothesis of an electrically tunable cytoskeleton where the dielectric properties of tubulin are polymerisation-state dependent.
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15
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Cantero MDR, Perez PL, Scarinci N, Cantiello HF. Two-Dimensional Brain Microtubule Structures Behave as Memristive Devices. Sci Rep 2019; 9:12398. [PMID: 31455820 PMCID: PMC6711987 DOI: 10.1038/s41598-019-48677-1] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2019] [Accepted: 08/06/2019] [Indexed: 02/03/2023] Open
Abstract
Microtubules (MTs) are cytoskeletal structures that play a central role in a variety of cell functions including cell division and cargo transfer. MTs are also nonlinear electrical transmission lines that produce and conduct electrical oscillations elicited by changes in either electric field and/or ionic gradients. The oscillatory behavior of MTs requires a voltage-sensitive gating mechanism to enable the electrodiffusional ionic movement through the MT wall. Here we explored the electrical response of non-oscillating rat brain MT sheets to square voltage steps. To ascertain the nature of the possible gating mechanism, the electrical response of non-oscillating rat brain MT sheets (2D arrays of MTs) to square pulses was analyzed under voltage-clamping conditions. A complex voltage-dependent nonlinear charge movement was observed, which represented the summation of two events. The first contribution was a small, saturating, voltage-dependent capacitance with a maximum charge displacement in the range of 4 fC/μm2. A second, major contribution was a non-saturating voltage-dependent charge transfer, consistent with the properties of a multistep memristive device. The memristive capabilities of MTs could drive oscillatory behavior, and enable voltage-driven neuromorphic circuits and architectures within neurons.
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Affiliation(s)
- María Del Rocío Cantero
- Laboratorio de Canales Iónicos, Instituto Multidisciplinario de Salud, Tecnología y Desarrollo (IMSaTeD), UNSE-CONICET, El Zanjón, Santiago del Estero, Argentina.
| | - Paula L Perez
- Laboratorio de Canales Iónicos, Instituto Multidisciplinario de Salud, Tecnología y Desarrollo (IMSaTeD), UNSE-CONICET, El Zanjón, Santiago del Estero, Argentina
| | - Noelia Scarinci
- Laboratorio de Canales Iónicos, Instituto Multidisciplinario de Salud, Tecnología y Desarrollo (IMSaTeD), UNSE-CONICET, El Zanjón, Santiago del Estero, Argentina
| | - Horacio F Cantiello
- Laboratorio de Canales Iónicos, Instituto Multidisciplinario de Salud, Tecnología y Desarrollo (IMSaTeD), UNSE-CONICET, El Zanjón, Santiago del Estero, Argentina
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16
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Frieden BR, Gatenby RA. Signal transmission through elements of the cytoskeleton form an optimized information network in eukaryotic cells. Sci Rep 2019; 9:6110. [PMID: 30992457 PMCID: PMC6467984 DOI: 10.1038/s41598-019-42343-2] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2018] [Accepted: 03/25/2019] [Indexed: 11/23/2022] Open
Abstract
Multiple prior empirical and theoretical studies have demonstrated wire-like flow of electrons and ions along elements of the cytoskeleton but this has never been linked to a biological function. Here we propose that eukaryotes use this mode of signal transmission to convey spatial and temporal environmental information from the cell membrane to the nucleus. The cell membrane, as the interface between intra- and extra-cellular environments, is the site at which much external information is received. Prior studies have demonstrated that transmembrane ion gradients permit information acquisition when an environmental signal interacts with specialized protein gates in membrane ion channels and producing specific ions to flow into or out of the cell along concentration gradients. The resulting localized change in cytoplasmic ion concentrations and charge density can alter location and enzymatic function of peripheral membrane proteins. This allows the cell to process the information and rapidly deploy a local response. Here we investigate transmission of information received and processed in and around the cell membrane by elements of the cytoskeleton to the nucleus to alter gene expression. We demonstrate signal transmission by ion flow along the cytoskeleton is highly optimized. In particular, microtubules, with diameters of about 30 nm, carry coarse-grained Shannon information to the centrosome adjacent to the nucleus with minimum loss of input source information. And, microfilaments, with diameters of about 4 nm, transmit maximum Fisher (fine-grained) information to protein complexes in the nuclear membrane. These previously unrecognized information dynamics allow continuous integration of spatial and temporal environmental signals with inherited information in the genome.
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Affiliation(s)
- B R Frieden
- College of Optical Science, University of Arizona, Tucson, AZ, USA
| | - R A Gatenby
- Department of Integrated Mathematical Biology, Moffitt Cancer Center, Tampa, FL, USA.
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