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Tunable and scalable fabrication of block copolymer-based 3D polymorphic artificial cell membrane array. Nat Commun 2022; 13:1261. [PMID: 35273189 PMCID: PMC8913694 DOI: 10.1038/s41467-022-28960-y] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2021] [Accepted: 02/16/2022] [Indexed: 12/13/2022] Open
Abstract
Owing to their excellent durability, tunable physical properties, and biofunctionality, block copolymer-based membranes provide a platform for various biotechnological applications. However, conventional approaches for fabricating block copolymer membranes produce only planar or suspended polymersome structures, which limits their utilization. This study is the first to demonstrate that an electric-field-assisted self-assembly technique can allow controllable and scalable fabrication of 3-dimensional block copolymer artificial cell membranes (3DBCPMs) immobilized on predefined locations. Topographically and chemically structured microwell array templates facilitate uniform patterning of block copolymers and serve as reactors for the effective growth of 3DBCPMs. Modulating the concentration of the block copolymer and the amplitude/frequency of the electric field generates 3DBCPMs with diverse shapes, controlled sizes, and high stability (100% survival over 50 days). In vitro protein–membrane assays and mimicking of human intestinal organs highlight the potential of 3DBCPMs for a variety of biological applications such as artificial cells, cell-mimetic biosensors, and bioreactors. In this manuscript, an electric-field-assisted self-assembly technique that can allow controllable and scalable fabrication of 3-dimensional block copolymer (BCP)-based artificial cell membranes (3DBCPMs) immobilized on predefined locations is presented. Topographically and chemically structured microwell array templates facilitate uniform patterning of BCPs and serve as reactors for the effective growth of 3DBCPMs, which diverse shapes, sizes and stability can be tuned by modulating the BCP concentration and the amplitude/frequency of the electric field. The potential of 3DBCPMs for a variety of biological applications is highlighted by performance of in vitro protein-membrane assays and mimicking of human intestinal organs.
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Boselli F, Jullien J, Lauga E, Goldstein RE. Fluid Mechanics of Mosaic Ciliated Tissues. PHYSICAL REVIEW LETTERS 2021; 127:198102. [PMID: 34797132 PMCID: PMC7616087 DOI: 10.1103/physrevlett.127.198102] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/30/2021] [Accepted: 10/07/2021] [Indexed: 06/13/2023]
Abstract
In tissues as diverse as amphibian skin and the human airway, the cilia that propel fluid are grouped in sparsely distributed multiciliated cells (MCCs). We investigate fluid transport in this "mosaic" architecture, with emphasis on the trade-offs that may have been responsible for its evolutionary selection. Live imaging of MCCs in embryos of the frog Xenopus laevis shows that cilia bundles behave as active vortices that produce a flow field accurately represented by a local force applied to the fluid. A coarse-grained model that self-consistently couples bundles to the ambient flow reveals that hydrodynamic interactions between MCCs limit their rate of work so that they best shear the tissue at a finite but low area coverage, a result that mirrors findings for other sparse distributions such as cell receptors and leaf stomata.
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Affiliation(s)
- Francesco Boselli
- Department of Applied Mathematics and Theoretical Physics, Centre for Mathematical Sciences, University of Cambridge, Cambridge CB3 0WA, United Kingdom
| | - Jerome Jullien
- Wellcome Trust/Cancer Research UK Gurdon Institute, Tennis Court Road, Cambridge CB2 1QN, United Kingdom
- Department of Zoology, University of Cambridge, Cambridge CB2 1QN, United Kingdom
- Inserm, Nantes Université, CHU Nantes, CRTI-UMR 1064, F-44000 Nantes, France
| | - Eric Lauga
- Department of Applied Mathematics and Theoretical Physics, Centre for Mathematical Sciences, University of Cambridge, Cambridge CB3 0WA, United Kingdom
| | - Raymond E. Goldstein
- Department of Applied Mathematics and Theoretical Physics, Centre for Mathematical Sciences, University of Cambridge, Cambridge CB3 0WA, United Kingdom
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Fatehiboroujeni S, Gopinath A, Goyal S. Three-dimensional nonlinear dynamics of prestressed active filaments: Flapping, swirling, and flipping. Phys Rev E 2021; 103:013005. [PMID: 33601644 DOI: 10.1103/physreve.103.013005] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2020] [Accepted: 12/24/2020] [Indexed: 11/07/2022]
Abstract
Initially straight slender elastic filaments or rods with constrained ends buckle and form stable two-dimensional shapes when prestressed by bringing the ends together. Beyond a critical value of this prestress, rods can also deform off plane and form twisted three-dimensional equilibrium shapes. Here, we analyze the three-dimensional instabilities and dynamics of such deformed filaments subject to nonconservative active follower forces and fluid drag. We find that softly constrained filaments that are clamped at one end and pinned at the other exhibit stable two-dimensional planar flapping oscillations when active forces are directed toward the clamped end. Reversing the directionality of the forces quenches the instability. For strongly constrained filaments with both ends clamped, computations reveal an instability arising from the twist-bend-activity coupling. Planar oscillations are destabilized by off-planar perturbations resulting in twisted three-dimensional swirling patterns interspersed with periodic flipping or reversal of the swirling direction. These striking swirl-flip transitions are characterized by two distinct timescales: the time period for a swirl (rotation) and the time between flipping events. We interpret these reversals as relaxation oscillation events driven by accumulation of torsional energy. Each cycle is initiated by a fast jump in torsional deformation with a subsequent slow decrease in net torsion until the next cycle. Our work reveals the rich tapestry of spatiotemporal patterns when weakly inertial strongly damped rods are deformed by nonconservative active forces. Taken together, our results suggest avenues by which prestress, elasticity, and activity may be used to design synthetic macroscale pumps or mixers.
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Affiliation(s)
- Soheil Fatehiboroujeni
- Department of Mechanical Engineering, University of California, Merced, California 95343, USA
| | - Arvind Gopinath
- Department of Bioengineering, University of California, Merced, California 95343, USA
| | - Sachin Goyal
- Department of Mechanical Engineering, University of California, Merced, California 95343, USA and Health Sciences Research Institute, University of California, Merced, California 95343, USA
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4
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Chelakkot R, Hagan MF, Gopinath A. Synchronized oscillations, traveling waves, and jammed clusters induced by steric interactions in active filament arrays. SOFT MATTER 2021; 17:1091-1104. [PMID: 33289748 DOI: 10.1039/d0sm01162b] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Autonomous active, elastic filaments that interact with each other to achieve cooperation and synchrony underlie many critical functions in biology. The mechanisms underlying this collective response and the essential ingredients for stable synchronization remain a mystery. Inspired by how these biological entities integrate elasticity with molecular motor activity to generate sustained oscillations, a number of synthetic active filament systems have been developed that mimic oscillations of these biological active filaments. Here, we describe the collective dynamics and stable spatiotemporal patterns that emerge in such biomimetic multi-filament arrays, under conditions where steric interactions may impact or dominate the collective dynamics. To focus on the role of steric interactions, we study the system using Brownian dynamics, without considering long-ranged hydrodynamic interactions. The simulations treat each filament as a connected chain of self-propelling colloids. We demonstrate that short-range steric inter-filament interactions and filament roughness are sufficient - even in the absence of inter-filament hydrodynamic interactions - to generate a rich variety of collective spatiotemporal oscillatory, traveling and static patterns. We first analyze the collective dynamics of two- and three-filament clusters and identify parameter ranges in which steric interactions lead to synchronized oscillations and strongly occluded states. Generalizing these results to large one-dimensional arrays, we find rich emergent behaviors, including traveling metachronal waves, and modulated wavetrains that are controlled by the interplay between the array geometry, filament activity, and filament elasticity. Interestingly, the existence of metachronal waves is non-monotonic with respect to the inter-filament spacing. We also find that the degree of filament roughness significantly affects the dynamics - specifically, filament roughness generates a locking-mechanism that transforms traveling wave patterns into statically stuck and jammed configurations. Taken together, simulations suggest that short-ranged steric inter-filament interactions could combine with complementary hydrodynamic interactions to control the development and regulation of oscillatory collective patterns. Furthermore, roughness and steric interactions may be critical to the development of jammed spatially periodic states; a spatiotemporal feature not observed in purely hydrodynamically interacting systems.
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Affiliation(s)
- Raghunath Chelakkot
- Department of Physics, Indian Institute of Technology Bombay, Mumbai, India.
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5
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Fily Y, Subramanian P, Schneider TM, Chelakkot R, Gopinath A. Buckling instabilities and spatio-temporal dynamics of active elastic filaments. J R Soc Interface 2020; 17:20190794. [PMID: 32316880 DOI: 10.1098/rsif.2019.0794] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Biological filaments driven by molecular motors tend to experience tangential propulsive forces also known as active follower forces. When such a filament encounters an obstacle, it deforms, which reorients its follower forces and alters its entire motion. If the filament pushes a cargo, the friction on the cargo can be enough to deform the filament, thus affecting the transport properties of the cargo. Motivated by cytoskeletal filament motility assays, we study the dynamic buckling instabilities of a two-dimensional slender elastic filament driven through a dissipative medium by tangential propulsive forces in the presence of obstacles or cargo. We observe two distinct instabilities. When the filament's head is pinned or experiences significant translational but little rotational drag from its cargo, it buckles into a steadily rotating coiled state. When it is clamped or experiences both significant translational and rotational drag from its cargo, it buckles into a periodically beating, overall translating state. Using minimal analytically tractable models, linear stability theory and fully nonlinear computations, we study the onset of each buckling instability, characterize each buckled state, and map out the phase diagram of the system. Finally, we use particle-based Brownian dynamics simulations to show our main results are robust to moderate noise and steric repulsion. Overall, our results provide a unified framework to understand the dynamics of tangentially propelled filaments and filament-cargo assemblies.
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Affiliation(s)
- Yaouen Fily
- Wilkes Honors College, Florida Atlantic University, Jupiter, FL, USA
| | | | - Tobias M Schneider
- Emergent Complexity in Physical Systems Laboratory (ECPS), Ecole Polytechnique Federale de Lausanne, CH 1015 Lausanne, Switzerland
| | | | - Arvind Gopinath
- Department of Bioengineering, University of California Merced, Merced, CA, USA
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6
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Zhu J, Jiang X, Zhong J, Duan Y. Polymer brushes and their possible applications in artificial cilia research. Mol Med Rep 2017; 15:3936-3942. [DOI: 10.3892/mmr.2017.6533] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2016] [Accepted: 02/20/2017] [Indexed: 11/06/2022] Open
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Brodsky M, Lesiak AJ, Croicu A, Cohenca N, Sullivan JM, Neumaier JF. 5-HT 6 receptor blockade regulates primary cilia morphology in striatal neurons. Brain Res 2017; 1660:10-19. [PMID: 28087224 DOI: 10.1016/j.brainres.2017.01.010] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2016] [Revised: 01/06/2017] [Accepted: 01/09/2017] [Indexed: 12/12/2022]
Abstract
The 5-HT6 receptor has been implicated in a variety of cognitive processes including habitual behaviors, learning, and memory. It is found almost exclusively in the brain, is expressed abundantly in striatum, and localizes to neuronal primary cilia. Primary cilia are antenna-like, sensory organelles found on most neurons that receive both chemical and mechanical signals from other cells and the surrounding environment; however, the effect of 5-HT6 receptor function on cellular morphology has not been examined. We confirmed that 5-HT6 receptors were localized to primary cilia in wild-type (WT) but not 5-HT6 knockout (5-HT6KO) in both native mouse brain tissue and primary cultured striatal neurons then used primary neurons cultured from WT or 5-HT6KO mice to study the function of these receptors. Selective 5-HT6 antagonists reduced cilia length in neurons cultured from wild-type mice in a concentration and time-dependent manner without altering dendrites, but had no effect on cilia length in 5-HT6KO cultured neurons. Varying the expression levels of heterologously expressed 5-HT6 receptors affected the fidelity of ciliary localization in both WT and 5-HT6KO neurons; overexpression lead to increasing amounts of 5-HT6 localization outside of the cilia but did not alter cilia morphology. Introducing discrete mutations into the third cytoplasmic loop of the 5-HT6 receptor greatly reduced, but did not entirely eliminate, trafficking of the 5-HT6 receptor to primary cilia. These data suggest that blocking 5-HT6 receptor activity reduces the length of primary cilia and that mechanisms that regulate trafficking of 5-HT6 receptors to cilia are more complex than previously thought.
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Affiliation(s)
- Matthew Brodsky
- Department of Psychiatry and Behavioral Sciences, University of Washington, Seattle, WA 98104, USA; Department of Pharmacology, University of Washington, Seattle, WA 98104, USA; Graduate Program in Neuroscience, University of Washington, Seattle, WA 98104, USA
| | - Adam J Lesiak
- Department of Psychiatry and Behavioral Sciences, University of Washington, Seattle, WA 98104, USA; Department of Pharmacology, University of Washington, Seattle, WA 98104, USA
| | - Alex Croicu
- Department of Psychiatry and Behavioral Sciences, University of Washington, Seattle, WA 98104, USA; Department of Pharmacology, University of Washington, Seattle, WA 98104, USA
| | - Nathalie Cohenca
- Department of Psychiatry and Behavioral Sciences, University of Washington, Seattle, WA 98104, USA; Department of Pharmacology, University of Washington, Seattle, WA 98104, USA
| | - Jane M Sullivan
- Department of Physiology & Biophysics, University of Washington, Seattle, WA 98104, USA; Graduate Program in Neuroscience, University of Washington, Seattle, WA 98104, USA
| | - John F Neumaier
- Department of Psychiatry and Behavioral Sciences, University of Washington, Seattle, WA 98104, USA; Department of Pharmacology, University of Washington, Seattle, WA 98104, USA.
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Abstract
The global rise in the prevalence of obesity and associated co-morbidities such as type 2 diabetes, cardiovascular disease, and cancer represents a major public health concern. The biological response to increased consumption of palatable foods or a reduction in energy expenditure is highly variable between individuals. A more detailed mechanistic understanding of the molecular, physiological, and behavioral pathways involved in the development of obesity in susceptible individuals is critical for identifying effective mechanism-based preventative and therapeutic interventions.
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Affiliation(s)
- Agatha A van der Klaauw
- University of Cambridge Metabolic Research Laboratories and NIHR Cambridge Biomedical Research Centre, Wellcome Trust-MRC Institute of Metabolic Science, Addenbrooke's Hospital, Cambridge CB2 0QQ, UK
| | - I Sadaf Farooqi
- University of Cambridge Metabolic Research Laboratories and NIHR Cambridge Biomedical Research Centre, Wellcome Trust-MRC Institute of Metabolic Science, Addenbrooke's Hospital, Cambridge CB2 0QQ, UK.
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10
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Diniz MC, Pacheco ACL, Farias KM, de Oliveira DM. The eukaryotic flagellum makes the day: novel and unforeseen roles uncovered after post-genomics and proteomics data. Curr Protein Pept Sci 2013; 13:524-46. [PMID: 22708495 PMCID: PMC3499766 DOI: 10.2174/138920312803582951] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2011] [Revised: 05/22/2012] [Accepted: 05/23/2012] [Indexed: 12/21/2022]
Abstract
This review will summarize and discuss the current biological understanding of the motile eukaryotic flagellum,
as posed out by recent advances enabled by post-genomics and proteomics approaches. The organelle, which is crucial
for motility, survival, differentiation, reproduction, division and feeding, among other activities, of many eukaryotes,
is a great example of a natural nanomachine assembled mostly by proteins (around 350-650 of them) that have been conserved
throughout eukaryotic evolution. Flagellar proteins are discussed in terms of their arrangement on to the axoneme,
the canonical “9+2” microtubule pattern, and also motor and sensorial elements that have been detected by recent proteomic
analyses in organisms such as Chlamydomonas reinhardtii, sea urchin, and trypanosomatids. Such findings can be
remarkably matched up to important discoveries in vertebrate and mammalian types as diverse as sperm cells, ciliated
kidney epithelia, respiratory and oviductal cilia, and neuro-epithelia, among others. Here we will focus on some exciting
work regarding eukaryotic flagellar proteins, particularly using the flagellar proteome of C. reinhardtii as a reference map
for exploring motility in function, dysfunction and pathogenic flagellates. The reference map for the eukaryotic flagellar
proteome consists of 652 proteins that include known structural and intraflagellar transport (IFT) proteins, less well-characterized
signal transduction proteins and flagellar associated proteins (FAPs), besides almost two hundred unannotated
conserved proteins, which lately have been the subject of intense investigation and of our present examination.
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Affiliation(s)
- Michely C Diniz
- Programa de Pós-Graduação em Biotecnologia-RENORBIO-Rede Nordeste de Biotecnologia, Universidade Estadual do Ceará-UECE, Av. Paranjana, 1700, Campus do Itaperi, Fortaleza, CE 60740-000 Brasil
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11
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Saidi Y, Hearn TJ, Coates JC. Function and evolution of 'green' GSK3/Shaggy-like kinases. TRENDS IN PLANT SCIENCE 2012; 17:39-46. [PMID: 22051150 DOI: 10.1016/j.tplants.2011.10.002] [Citation(s) in RCA: 74] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/01/2011] [Revised: 09/22/2011] [Accepted: 10/05/2011] [Indexed: 05/20/2023]
Abstract
Glycogen synthase kinase 3 (GSK3) proteins, also known as SHAGGY-like kinases, have many important cell signalling roles in animals, fungi and amoebae. In particular, GSK3s participate in key developmental signalling pathways and also regulate the cytoskeleton. GSK3-encoding genes are also present in all land plants and in algae and protists, raising questions about possible ancestral functions in eukaryotes. Recent studies have revealed that plant GSK3 proteins are actively implicated in hormonal signalling networks during development as well as in biotic and abiotic stress responses. In this review, we outline the mechanisms of Arabidopsis GSK3 action, summarize GSK3 functions in dicot and monocot flowering plants, and speculate on the possible functions of GSK3s in the earliest-evolving land plants.
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Affiliation(s)
- Younousse Saidi
- School of Biosciences, University of Birmingham, Edgbaston, Birmingham, B15 2TT, United Kingdom
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12
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Kotov NV, Bates DG, Gizatullina AN, Gilaziev B, Khairullin RN, Chen MZQ, Drozdov I, Umezawa Y, Hundhausen C, Aleksandrov A, Yan XG, Spurgeon SK, Smales CM, Valeyev NV. Computational modelling elucidates the mechanism of ciliary regulation in health and disease. BMC SYSTEMS BIOLOGY 2011; 5:143. [PMID: 21920041 PMCID: PMC3224258 DOI: 10.1186/1752-0509-5-143] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/13/2011] [Accepted: 09/15/2011] [Indexed: 12/23/2022]
Abstract
Background Ciliary dysfunction leads to a number of human pathologies, including primary ciliary dyskinesia, nephronophthisis, situs inversus pathology or infertility. The mechanism of cilia beating regulation is complex and despite extensive experimental characterization remains poorly understood. We develop a detailed systems model for calcium, membrane potential and cyclic nucleotide-dependent ciliary motility regulation. Results The model describes the intimate relationship between calcium and potassium ionic concentrations inside and outside of cilia with membrane voltage and, for the first time, describes a novel type of ciliary excitability which plays the major role in ciliary movement regulation. Our model describes a mechanism that allows ciliary excitation to be robust over a wide physiological range of extracellular ionic concentrations. The model predicts the existence of several dynamic modes of ciliary regulation, such as the generation of intraciliary Ca2+ spike with amplitude proportional to the degree of membrane depolarization, the ability to maintain stable oscillations, monostable multivibrator regimes, all of which are initiated by variability in ionic concentrations that translate into altered membrane voltage. Conclusions Computational investigation of the model offers several new insights into the underlying molecular mechanisms of ciliary pathologies. According to our analysis, the reported dynamic regulatory modes can be a physiological reaction to alterations in the extracellular environment. However, modification of the dynamic modes, as a result of genetic mutations or environmental conditions, can cause a life threatening pathology.
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Affiliation(s)
- Nikolay V Kotov
- Centre for Molecular Processing, School of Biosciences, University of Kent, Canterbury, Kent, UK
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Ramachandrappa S, Farooqi IS. Genetic approaches to understanding human obesity. J Clin Invest 2011; 121:2080-6. [PMID: 21633175 DOI: 10.1172/jci46044] [Citation(s) in RCA: 139] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Obesity and its associated comorbidities represent one of the biggest public health challenges facing the world today. The heritability of body weight is high, and genetic variation plays a major role in determining the interindividual differences in susceptibility or resistance to the obesogenic environment. Here we discuss how genetic studies in humans have contributed to our understanding of the central pathways that govern energy homeostasis. We discuss how the arrival of technological advances such as next-generation sequencing will result in a major acceleration in the pace of gene discovery. The study of patients harboring these genetic variants has informed our understanding of the molecular and physiological pathways involved in energy homeostasis. We anticipate that future studies will provide the framework for the development of a more rational targeted approach to the prevention and treatment of genetically susceptible individuals.
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Affiliation(s)
- Shwetha Ramachandrappa
- University of Cambridge Metabolic Research Laboratories, Institute of Metabolic Science, Addenbrooke's Hospital, Cambridge, United Kingdom
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Goldstein RE, Polin M, Tuval I. Noise and synchronization in pairs of beating eukaryotic flagella. PHYSICAL REVIEW LETTERS 2009; 103:168103. [PMID: 19905728 DOI: 10.1103/physrevlett.103.168103] [Citation(s) in RCA: 99] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/10/2009] [Indexed: 05/28/2023]
Abstract
It has long been conjectured that hydrodynamic interactions between beating eukaryotic flagella underlie their ubiquitous forms of synchronization; yet there has been no experimental test of this connection. The biflagellate alga Chlamydomonas is a simple model for such studies, as its two flagella are representative of those most commonly found in eukaryotes. Using micromanipulation and high-speed imaging, we show that the flagella of a C. reinhardtii cell present periods of synchronization interrupted by phase slips. The dynamics of slips and the statistics of phase-locked intervals are consistent with a low-dimensional stochastic model of hydrodynamically coupled oscillators, with a noise amplitude set by the intrinsic fluctuations of single flagellar beats.
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Affiliation(s)
- Raymond E Goldstein
- Department of Applied Mathematics and Theoretical Physics, University of Cambridge, Wilberforce Road, Cambridge CB3 0WA, United Kingdom
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Wang Z, Li V, Chan GCK, Phan T, Nudelman AS, Xia Z, Storm DR. Adult type 3 adenylyl cyclase-deficient mice are obese. PLoS One 2009; 4:e6979. [PMID: 19750222 PMCID: PMC2735775 DOI: 10.1371/journal.pone.0006979] [Citation(s) in RCA: 117] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2009] [Accepted: 08/13/2009] [Indexed: 11/19/2022] Open
Abstract
Background A recent study of obesity in Swedish men found that polymorphisms in the type 3 adenylyl cyclase (AC3) are associated with obesity, suggesting the interesting possibility that AC3 may play a role in weight control. Therefore, we examined the weight of AC3 mice over an extended period of time. Methodology/Principal Findings We discovered that AC3−/− mice become obese as they age. Adult male AC3−/− mice are about 40% heavier than wild type male mice while female AC3−/− are 70% heavier. The additional weight of AC3−/− mice is due to increased fat mass and larger adipocytes. Before the onset of obesity, young AC3−/− mice exhibit reduced physical activity, increased food consumption, and leptin insensitivity. Surprisingly, the obesity of AC3−/− mice is not due to a loss of AC3 from white adipose and a decrease in lipolysis. Conclusions/Significance We conclude that mice lacking AC3 exhibit obesity that is apparently caused by low locomotor activity, hyperphagia, and leptin insensitivity. The presence of AC3 in primary cilia of neurons of the hypothalamus suggests that cAMP signals generated by AC3 in the hypothalamus may play a critical role in regulation of body weight.
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Affiliation(s)
- Zhenshan Wang
- Department of Pharmacology, University of Washington, Seattle, Washington, United States of America
| | - Vicky Li
- Department of Pharmacology, University of Washington, Seattle, Washington, United States of America
| | - Guy C. K. Chan
- Department of Pharmacology, University of Washington, Seattle, Washington, United States of America
| | - Trongha Phan
- Department of Pharmacology, University of Washington, Seattle, Washington, United States of America
| | - Aaron S. Nudelman
- Department of Pharmacology, University of Washington, Seattle, Washington, United States of America
| | - Zhengui Xia
- Department of Pharmacology, University of Washington, Seattle, Washington, United States of America
| | - Daniel R. Storm
- Department of Pharmacology, University of Washington, Seattle, Washington, United States of America
- * E-mail:
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Polin M, Tuval I, Drescher K, Gollub JP, Goldstein RE. Chlamydomonas swims with two "gears" in a eukaryotic version of run-and-tumble locomotion. Science 2009; 325:487-90. [PMID: 19628868 DOI: 10.1126/science.1172667] [Citation(s) in RCA: 226] [Impact Index Per Article: 15.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
The coordination of eukaryotic flagella is essential for many of the most basic processes of life (motility, sensing, and development), yet its emergence and regulation and its connection to locomotion are poorly understood. Previous studies show that the unicellular alga Chlamydomonas, widely regarded as an ideal system in which to study flagellar biology, swims forward by the synchronous action of its two flagella. Using high-speed imaging over long intervals, we found a richer behavior: A cell swimming in the dark stochastically switches between synchronous and asynchronous flagellar beating. Three-dimensional tracking shows that these regimes lead, respectively, to nearly straight swimming and to abrupt large reorientations, which yield a eukaryotic version of the "run-and-tumble" motion of peritrichously flagellated bacteria.
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Affiliation(s)
- Marco Polin
- Department of Applied Mathematics and Theoretical Physics, University of Cambridge, Wilberforce Road, Cambridge CB3 0WA, UK
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Hashimoto H, Miyamoto R, Watanabe N, Shiba D, Ozato K, Inoue C, Kubo Y, Koga A, Jindo T, Narita T, Naruse K, Ohishi K, Nogata K, Shin-I T, Asakawa S, Shimizu N, Miyamoto T, Mochizuki T, Yokoyama T, Hori H, Takeda H, Kohara Y, Wakamatsu Y. Polycystic kidney disease in the medaka (Oryzias latipes) pc mutant caused by a mutation in the Gli-Similar3 (glis3) gene. PLoS One 2009; 4:e6299. [PMID: 19609364 PMCID: PMC2706989 DOI: 10.1371/journal.pone.0006299] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2009] [Accepted: 06/09/2009] [Indexed: 11/24/2022] Open
Abstract
Polycystic kidney disease (PKD) is a common hereditary disease in humans. Recent studies have shown an increasing number of ciliary genes that are involved in the pathogenesis of PKD. In this study, the Gli-similar3 (glis3) gene was identified as the causal gene of the medaka pc mutant, a model of PKD. In the pc mutant, a transposon was found to be inserted into the fourth intron of the pc/glis3 gene, causing aberrant splicing of the pc/glis3 mRNA and thus a putatively truncated protein with a defective zinc finger domain. pc/glis3 mRNA is expressed in the epithelial cells of the renal tubules and ducts of the pronephros and mesonephros, and also in the pancreas. Antisense oligonucleotide-mediated knockdown of pc/glis3 resulted in cyst formation in the pronephric tubules of medaka fry. Although three other glis family members, glis1a, glis1b and glis2, were found in the medaka genome, none were expressed in the embryonic or larval kidney. In the pc mutant, the urine flow rate in the pronephros was significantly reduced, which was considered to be a direct cause of renal cyst formation. The cilia on the surface of the renal tubular epithelium were significantly shorter in the pc mutant than in wild-type, suggesting that shortened cilia resulted in a decrease in driving force and, in turn, a reduction in urine flow rate. Most importantly, EGFP-tagged pc/glis3 protein localized in primary cilia as well as in the nucleus when expressed in mouse renal epithelial cells, indicating a strong connection between pc/glis3 and ciliary function. Unlike human patients with GLIS3 mutations, the medaka pc mutant shows none of the symptoms of a pancreatic phenotype, such as impaired insulin expression and/or diabetes, suggesting that the pc mutant may be suitable for use as a kidney-specific model for human GLIS3 patients.
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Affiliation(s)
- Hisashi Hashimoto
- Bioscience and Biotechnology Center, Nagoya University, Nagoya, Japan.
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Walther A, Müller AHE. Formation of hydrophobic bridges between multicompartment micelles of miktoarm star terpolymers in water. Chem Commun (Camb) 2009:1127-9. [DOI: 10.1039/b820507h] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Abstract
In unicellular and multicellular eukaryotes, fast cell motility and rapid movement of material over cell surfaces are often mediated by ciliary or flagellar beating. The conserved defining structure in most motile cilia and flagella is the '9+2' microtubule axoneme. Our general understanding of flagellum assembly and the regulation of flagellar motility has been led by results from seminal studies of flagellate protozoa and algae. Here we review recent work relating to various aspects of protist physiology and cell biology. In particular, we discuss energy metabolism in eukaryotic flagella, modifications to the canonical assembly pathway and flagellum function in parasite virulence.
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Abstract
Flagella are sensory organelles that interact with the environment through signal transduction and gene expression networks. We used microarray profiling to examine gene regulation associated with flagellar length change in the green alga Chlamydomonas reinhardtii. Microarrays were probed with fluorescently labeled cDNAs synthesized from RNA extracted from cells before and during flagellar assembly or disassembly. Evaluation of the gene expression profiles identified >100 clones showing at least a twofold change in expression during flagellar length changes. Products of these genes are associated not only with flagellar structure and motility but also with other cellular responses, including signal transduction and metabolism. Expression of specific genes from each category was further characterized at higher resolution by using quantitative real-time PCR (qRT-PCR). Analysis and comparison of the gene expression profiles coupled to flagellar assembly and disassembly revealed that each process involves a new and uncharacterized whole-cell response to flagellar length changes. This analysis lays the groundwork for a more comprehensive understanding of the cellular and molecular networks regulating flagellar length changes.
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Abstract
Cilia are present on nearly all cell types in mammals and perform remarkably diverse functions. However, the mechanisms underlying ciliogenesis are unclear. Here, we cloned a previously uncharacterized highly conserved gene, stumpy, located on mouse chromosome 7. Stumpy was ubiquitously expressed, and conditional loss in mouse resulted in complete penetrance of perinatal hydrocephalus (HC) and severe polycystic kidney disease (PKD). We found that cilia in stumpy mutant brain and kidney cells were absent or markedly deformed, resulting in defective flow of cerebrospinal fluid. Stumpy colocalized with ciliary basal bodies, physically interacted with gamma-tubulin, and was present along ciliary axonemes, suggesting that stumpy plays a role in ciliary axoneme extension. Therefore, stumpy is essential for ciliogenesis and may be involved in the pathogenesis of human congenital malformations such as HC and PKD.
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