1
|
Patel MB, Griffin PJ, Olson SF, Dai J, Hou Y, Malik T, Das P, Zhang G, Zhao W, Witman GB, Lechtreck KF. Distribution and bulk flow analyses of the intraflagellar transport (IFT) motor kinesin-2 support an "on-demand" model for Chlamydomonas ciliary length control. Cytoskeleton (Hoboken) 2024. [PMID: 38456596 PMCID: PMC11380706 DOI: 10.1002/cm.21851] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2023] [Revised: 02/22/2024] [Accepted: 02/23/2024] [Indexed: 03/09/2024]
Abstract
Most cells tightly control the length of their cilia. The regulation likely involves intraflagellar transport (IFT), a bidirectional motility of multi-subunit particles organized into trains that deliver building blocks into the organelle. In Chlamydomonas, the anterograde IFT motor kinesin-2 consists of the motor subunits FLA8 and FLA10 and the nonmotor subunit KAP. KAP dissociates from IFT at the ciliary tip and diffuses back to the cell body. This observation led to the diffusion-as-a-ruler model of ciliary length control, which postulates that KAP is progressively sequestered into elongating cilia because its return to the cell body will require increasingly more time, limiting motor availability at the ciliary base, train assembly, building block supply, and ciliary growth. Here, we show that Chlamydomonas FLA8 also returns to the cell body by diffusion. However, more than 95% of KAP and FLA8 are present in the cell body and, at a given time, just ~1% of the motor participates in IFT. After repeated photobleaching of both cilia, IFT of fluorescent kinesin subunits continued indicating that kinesin-2 cycles from the large cell-body pool through the cilia and back. Furthermore, growing and full-length cilia contained similar amounts of kinesin-2 subunits and the size of the motor pool at the base changed only slightly with ciliary length. These observations are incompatible with the diffusion-as-a-ruler model, but rather support an "on-demand model," in which the cargo load of the trains is regulated to assemble cilia of the desired length.
Collapse
Affiliation(s)
- Mansi B Patel
- Department of Cellular Biology, University of Georgia, Athens, Georgia, USA
| | - Paul J Griffin
- Department of Cellular Biology, University of Georgia, Athens, Georgia, USA
| | - Spencer F Olson
- Department of Cellular Biology, University of Georgia, Athens, Georgia, USA
| | - Jin Dai
- Department of Cellular Biology, University of Georgia, Athens, Georgia, USA
| | - Yuqing Hou
- Department of Radiology, UMass Chan Medical School, Worcester, Massachusetts, USA
| | - Tara Malik
- Department of Cellular Biology, University of Georgia, Athens, Georgia, USA
| | - Poulomi Das
- Department of Cellular Biology, University of Georgia, Athens, Georgia, USA
| | - Gui Zhang
- Department of Cellular Biology, University of Georgia, Athens, Georgia, USA
| | - Winston Zhao
- Department of Radiology, UMass Chan Medical School, Worcester, Massachusetts, USA
| | - George B Witman
- Department of Radiology, UMass Chan Medical School, Worcester, Massachusetts, USA
| | - Karl F Lechtreck
- Department of Cellular Biology, University of Georgia, Athens, Georgia, USA
| |
Collapse
|
2
|
Devarajan K, Sivakalai M, Basu SM, Biswas C, Chauhan M, Hasan U, Panneerselvam Y, Narayanan UM, Raavi SSK, Giri J, Panda TK. Design and synthesis of photostable triphenylamine based neutral AIE nano luminogens: specific and long-term tracking of mitochondria in cells. Biomater Sci 2023; 11:3938-3951. [PMID: 37093244 DOI: 10.1039/d3bm00043e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/25/2023]
Abstract
With the increasing dependence on fluorescence bioimaging, luminogens with aggregation-induced emission (AIE) properties have gained significant attention due to their excellent photostabilization, minimal photobleaching, high reliability, and superior biocompatibility. Since mitochondria are crucial subcellular organelles in eukaryotic cells with important biological functions, organelle-specific AIE emitters with distinct functions have been highly sought after, but with limited success using simple synthetic methods. Here, we describe a strategy for synthesizing two triphenylamine (TPA) based acrylonitriles, tethered to different donor groups, TPA and phenothiazine (PTZ), respectively, with superior AIE properties using Suzuki coupling. We conducted a systematic and detailed experimental analysis of the structural characteristics of both AIE luminogens, which exhibited excellent photostability, a large Stokes shift, and bright solid-state emission. A cell viability study carried out with F1 and F2 dyes revealed that both luminogens exhibited excellent biocompatibility. Based on fluorescence experiments, F2 displayed excellent AIE characteristics, permeability, biocompatibility, and photostability compared to rhodamine 123, allowing it to selectively stain and track mitochondria in cancer cells over an extended period of time. The Pearson correlation coefficient of F2 and rhodamine 123 was estimated to have an r-value of 0.99. Our findings are expected to provide insight into the synthesis of an extensive archive of AIE-based acrylonitriles with fascinating properties for mitochondrial staining.
Collapse
Affiliation(s)
| | - Mayakrishnan Sivakalai
- Organic & Bioorganic Chemistry Laboratory, CSIR-Central Leather Research Institute, Chennai, 600020, India.
- CSIR-North East Institute of Science & Technology (NEIST), Branch Laboratory, Imphal-795004, Manipur, India
| | - Suparna Mercy Basu
- Department of Biomedical Engineering, Indian Institute of Technology Hyderabad, Telangana, India.
| | - Chinmoy Biswas
- Department of Physics, Indian Institute of Technology Hyderabad, 502 285, India.
| | - Meenakshi Chauhan
- Department of Biomedical Engineering, Indian Institute of Technology Hyderabad, Telangana, India.
| | - Uzma Hasan
- Department of Biomedical Engineering, Indian Institute of Technology Hyderabad, Telangana, India.
- Department of Biotechnology, Indian Institute of Technology Hyderabad, Telangana, India
| | - Yuvaraj Panneerselvam
- CSIR-North East Institute of Science & Technology (NEIST), Branch Laboratory, Imphal-795004, Manipur, India
| | - Uma Maheswari Narayanan
- Organic & Bioorganic Chemistry Laboratory, CSIR-Central Leather Research Institute, Chennai, 600020, India.
| | | | - Jyotsnendu Giri
- Department of Biomedical Engineering, Indian Institute of Technology Hyderabad, Telangana, India.
| | - Tarun K Panda
- Department of Chemistry, Indian Institute of Technology Hyderabad, 502285, India.
| |
Collapse
|
3
|
Bigge BM, Dougherty LL, Avasthi P. Lithium-induced ciliary lengthening sparks Arp2/3 complex-dependent endocytosis. Mol Biol Cell 2023; 34:ar26. [PMID: 36753380 PMCID: PMC10092651 DOI: 10.1091/mbc.e22-06-0219] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/09/2023] Open
Abstract
Ciliary length is highly regulated, but can be disrupted by lithium, which causes ciliary elongation across cell types and organisms. We used the algal system Chlamydomonas reinhardtii to investigate the mechanism behind lithium-induced ciliary elongation. Protein synthesis is not required for lengthening, and the target of lithium, GSK3, has substrates that can influence membrane dynamics. Further, ciliary assembly requires a supply of ciliary membrane as well as protein. Lithium-treated cilia elongate normally with brefeldin treatment, but dynasore treatment produced defective lengthening suggesting a source of membrane from the cell surface rather than the Golgi. Genetic or chemical perturbation of the Arp2/3 complex or dynamin, required for endocytosis, blocks lithium-induced ciliary lengthening. Finally, we found an increase in Arp2/3 complex- and endocytosis-dependent actin filaments near the ciliary base upon lithium treatment. Our results identify a mechanism for lithium-mediated cilium lengthening and demonstrate the endocytic pathway for cilium membrane supply in algae is likely a conserved mechanism given lithium's conserved effects across organisms.
Collapse
Affiliation(s)
- Brae M Bigge
- Department of Biochemistry and Cell Biology, Geisel School of Medicine, Dartmouth College, Hanover, NH 03755
| | - Larissa L Dougherty
- Department of Biochemistry and Cell Biology, Geisel School of Medicine, Dartmouth College, Hanover, NH 03755
| | - Prachee Avasthi
- Department of Biochemistry and Cell Biology, Geisel School of Medicine, Dartmouth College, Hanover, NH 03755
| |
Collapse
|
4
|
Al-Hiyasat A, Tuna Y, Kuo YW, Howard J. Herding of proteins by the ends of shrinking polymers. Phys Rev E 2023; 107:L042601. [PMID: 37198784 DOI: 10.1103/physreve.107.l042601] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2022] [Accepted: 02/17/2023] [Indexed: 05/19/2023]
Abstract
The control of biopolymer length is mediated by proteins that localize to polymer ends and regulate polymerization dynamics. Several mechanisms have been proposed to achieve end localization. Here, we propose a novel mechanism by which a protein that binds to a shrinking polymer and slows its shrinkage will be spontaneously enriched at the shrinking end through a "herding" effect. We formalize this process using both lattice-gas and continuum descriptions, and we present experimental evidence that the microtubule regulator spastin employs this mechanism. Our findings extend to more general problems involving diffusion within shrinking domains.
Collapse
Affiliation(s)
- Amer Al-Hiyasat
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut 06511, USA
- Department of Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - Yazgan Tuna
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut 06511, USA
| | - Yin-Wei Kuo
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut 06511, USA
| | - Jonathon Howard
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut 06511, USA
| |
Collapse
|
5
|
Single p197 molecules of the mitochondrial genome segregation system of Trypanosoma brucei determine the distance between basal body and outer membrane. Proc Natl Acad Sci U S A 2022; 119:e2204294119. [PMID: 36161893 PMCID: PMC9546609 DOI: 10.1073/pnas.2204294119] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Segregation of the replicated single unit mitochondrial genome of Trypanosoma brucei requires a large hardwired structure that connects the organellar DNA with the flagellar basal body. The cytosolic part of this structure consists of filaments made of p197 molecules, a protein with a molecular weight of approximately 660 kDa. The N terminus of p197 is anchored to the peripheral mitochondrial outer membrane protein TAC65, whereas its C terminus connects to the base of the basal body. The large α-helical central domain of p197 consists of approximately 26 repeats each 175 aa in length. It provides a flexible spacer that connects the outer membrane with the basal body and determines the distance between the two structures. The tripartite attachment complex (TAC) couples the segregation of the single unit mitochondrial DNA of trypanosomes with the basal body (BB) of the flagellum. Here, we studied the architecture of the exclusion zone filament (EZF) of the TAC, the only known component of which is p197, that connects the BB with the mitochondrial outer membrane (OM). We show that p197 has three domains that are all essential for mitochondrial DNA inheritance. The C terminus of p197 interacts with the mature and probasal body (pro-BB), whereas its N terminus binds to the peripheral OM protein TAC65. The large central region of p197 has a high α-helical content and likely acts as a flexible spacer. Ultrastructure expansion microscopy (U-ExM) of cell lines exclusively expressing p197 versions of different lengths that contain both N- and C-terminal epitope tags demonstrates that full-length p197 alone can bridge the ∼270-nm distance between the BB and the cytosolic face of the OM. Thus U-ExM allows the localization of distinct domains within the same molecules and suggests that p197 is the TAC subunit most proximal to the BB. In addition, U-ExM revealed that p197 acts as a spacer molecule, as two shorter versions of p197, with the repeat domain either removed or replaced by the central domain of the Trypanosoma cruzi p197 ortholog reduced the distance between the BB and the OM in proportion to their predicted molecular weight.
Collapse
|
6
|
Ortolan D, Sharma R, Volkov A, Maminishkis A, Hotaling NA, Huryn LA, Cukras C, Di Marco S, Bisti S, Bharti K. Single-cell-resolution map of human retinal pigment epithelium helps discover subpopulations with differential disease sensitivity. Proc Natl Acad Sci U S A 2022; 119:e2117553119. [PMID: 35522714 PMCID: PMC9171647 DOI: 10.1073/pnas.2117553119] [Citation(s) in RCA: 40] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2021] [Accepted: 03/25/2022] [Indexed: 12/31/2022] Open
Abstract
Regional phenotypic and functional differences in the retinal pigment epithelium (RPE) monolayer have been suggested to account for regional susceptibility in ocular diseases such as age-related macular degeneration (AMD), late-onset retinal degeneration (L-ORD), and choroideremia (CHM). However, a comprehensive description of human topographical RPE diversity is not yet available, thus limiting the understanding of regional RPE diversity and degenerative disease sensitivity in the eye. To develop a complete morphometric RPE map of the human eye, artificial intelligence–based software was trained to recognize, segment, and analyze RPE borders. Five statistically different, concentric RPE subpopulations (P1 to P5) were identified using cell area as a parameter, including a subpopulation (P4) with cell area comparable to that of macular cells in the far periphery of the eye. This work provides a complete reference map of human RPE subpopulations and their location in the eye. In addition, the analysis of cadaver non-AMD and AMD eyes and ultra-widefield fundus images of patients revealed differential vulnerability of the five RPE subpopulations to different retinal diseases.
Collapse
Affiliation(s)
- Davide Ortolan
- Ocular and Stem Cell Translational Research Section, National Eye Institute, NIH, Bethesda, MD 20892
| | - Ruchi Sharma
- Ocular and Stem Cell Translational Research Section, National Eye Institute, NIH, Bethesda, MD 20892
| | - Andrei Volkov
- Ocular and Stem Cell Translational Research Section, National Eye Institute, NIH, Bethesda, MD 20892
| | - Arvydas Maminishkis
- Ocular and Stem Cell Translational Research Section, National Eye Institute, NIH, Bethesda, MD 20892
| | - Nathan A. Hotaling
- Information Resources Technology Branch, National Center for Advancing Translational Sciences, NIH, Bethesda, MD 20892
| | - Laryssa A. Huryn
- Ophthalmic Clinical Genetics Section, National Eye Institute, NIH, Bethesda, MD 20892
| | - Catherine Cukras
- Unit on Clinical Investigation of Retinal Disease, National Eye Institute, NIH, Bethesda, MD 20892
| | - Stefano Di Marco
- Center for Synaptic Neuroscience and Technology, Istituto Italiano di Tecnologia, 16132 Genova, Italy
| | - Silvia Bisti
- Center for Synaptic Neuroscience and Technology, Istituto Italiano di Tecnologia, 16132 Genova, Italy
- Biostructures and Biosystems National Institute, 00136 Roma, Italy
| | - Kapil Bharti
- Ocular and Stem Cell Translational Research Section, National Eye Institute, NIH, Bethesda, MD 20892
| |
Collapse
|
7
|
Cunha F, Gutiérrez-Ibáñez C, Racicot K, Wylie DR, Iwaniuk AN. A quantitative analysis of cerebellar anatomy in birds. Brain Struct Funct 2021; 226:2561-2583. [PMID: 34357439 DOI: 10.1007/s00429-021-02352-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2021] [Accepted: 07/26/2021] [Indexed: 12/19/2022]
Abstract
The cerebellum is largely conserved in its circuitry, but varies greatly in size and shape across species. The extent to which differences in cerebellar morphology is driven by changes in neuron numbers, neuron sizes or both, remains largely unknown. To determine how species variation in cerebellum size and shape is reflective of neuron sizes and numbers requires the development of a suitable comparative data set and one that can effectively separate different neuronal populations. Here, we generated the largest comparative dataset to date on neuron numbers, sizes, and volumes of cortical layers and surface area of the cerebellum across 54 bird species. Across different cerebellar sizes, the cortical layers maintained relatively constant proportions to one another and variation in cerebellum size was largely due to neuron numbers rather than neuron sizes. However, the rate at which neuron numbers increased with cerebellum size varied across Purkinje cells, granule cells, and cerebellar nuclei neurons. We also examined the relationship among neuron numbers, cerebellar surface area and cerebellar folding. Our estimate of cerebellar folding, the midsagittal foliation index, was a poor predictor of surface area and number of Purkinje cells, but surface area was the best predictor of Purkinje cell numbers. Overall, this represents the first comprehensive, quantitative analysis of cerebellar anatomy in a comparative context of any vertebrate. The extent to which these relationships occur in other vertebrates requires a similar approach and would determine whether the same scaling principles apply throughout the evolution of the cerebellum.
Collapse
Affiliation(s)
- Felipe Cunha
- Department of Neuroscience, University of Lethbridge, 4401 University Dr. W, Science & Academic Building, SA8150, Lethbridge, AB, T1K 6T5, Canada.
| | | | - Kelsey Racicot
- Department of Neuroscience, University of Lethbridge, 4401 University Dr. W, Science & Academic Building, SA8150, Lethbridge, AB, T1K 6T5, Canada
| | - Douglas R Wylie
- Department of Biological Sciences, University of Alberta, Edmonton, AB, Canada
| | - Andrew N Iwaniuk
- Department of Neuroscience, University of Lethbridge, 4401 University Dr. W, Science & Academic Building, SA8150, Lethbridge, AB, T1K 6T5, Canada
| |
Collapse
|
8
|
Baluška F, Miller WB, Reber AS. Biomolecular Basis of Cellular Consciousness via Subcellular Nanobrains. Int J Mol Sci 2021; 22:ijms22052545. [PMID: 33802617 PMCID: PMC7961929 DOI: 10.3390/ijms22052545] [Citation(s) in RCA: 30] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2021] [Revised: 02/24/2021] [Accepted: 02/25/2021] [Indexed: 02/07/2023] Open
Abstract
Cells emerged at the very beginning of life on Earth and, in fact, are coterminous with life. They are enclosed within an excitable plasma membrane, which defines the outside and inside domains via their specific biophysical properties. Unicellular organisms, such as diverse protists and algae, still live a cellular life. However, fungi, plants, and animals evolved a multicellular existence. Recently, we have developed the cellular basis of consciousness (CBC) model, which proposes that all biological awareness, sentience and consciousness are grounded in general cell biology. Here we discuss the biomolecular structures and processes that allow for and maintain this cellular consciousness from an evolutionary perspective.
Collapse
Affiliation(s)
- František Baluška
- Institute of Cellular and Molecular Botany, University of Bonn, 53115 Bonn, Germany
- Correspondence:
| | | | - Arthur S. Reber
- Department of Psychology, University of British Columbia, Vancouver, BC V6T 1Z4, Canada;
| |
Collapse
|
9
|
Rieckhoff EM, Berndt F, Elsner M, Golfier S, Decker F, Ishihara K, Brugués J. Spindle Scaling Is Governed by Cell Boundary Regulation of Microtubule Nucleation. Curr Biol 2020; 30:4973-4983.e10. [DOI: 10.1016/j.cub.2020.10.093] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2020] [Revised: 10/11/2020] [Accepted: 10/29/2020] [Indexed: 02/08/2023]
|
10
|
Weck ML, Crawley SW, Tyska MJ. A heterologous in-cell assay for investigating intermicrovillar adhesion complex interactions reveals a novel protrusion length-matching mechanism. J Biol Chem 2020; 295:16191-16206. [PMID: 33051206 DOI: 10.1074/jbc.ra120.015929] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2020] [Revised: 09/30/2020] [Indexed: 01/18/2023] Open
Abstract
Solute transporting epithelial cells build arrays of microvilli on their apical surface to increase membrane scaffolding capacity and enhance function potential. In epithelial tissues such as the kidney and gut, microvilli are length-matched and assembled into tightly packed "brush borders," which are organized by ∼50-nm thread-like links that form between the distal tips of adjacent protrusions. Composed of protocadherins CDHR2 and CDHR5, adhesion links are stabilized at the tips by a cytoplasmic tripartite module containing the scaffolds USH1C and ANKS4B and the actin-based motor MYO7B. Because several questions about the formation and function of this "intermicrovillar adhesion complex" remain open, we devised a system that allows one to study individual binary interactions between specific complex components and MYO7B. Our approach employs a chimeric myosin consisting of the MYO10 motor domain fused to the MYO7B cargo-binding tail domain. When expressed in HeLa cells, which do not normally produce adhesion complex proteins, this chimera trafficked to the tips of filopodia and was also able to transport individual complex components to these sites. Unexpectedly, the MYO10-MYO7B chimera was able to deliver CDHR2 and CDHR5 to distal tips in the absence of USH1C or ANKS4B. Cells engineered to localize high levels of CDHR2 at filopodial tips acquired interfilopodial adhesion and exhibited a striking dynamic length-matching activity that aligned distal tips over time. These findings deepen our understanding of mechanisms that promote the distal tip accumulation of intermicrovillar adhesion complex components and also offer insight on how epithelial cells minimize microvillar length variability.
Collapse
Affiliation(s)
- Meredith L Weck
- Department of Cell and Developmental Biology, Vanderbilt University, Nashville, Tennessee, USA
| | - Scott W Crawley
- Department of Biology, University of Toledo, Toledo, Ohio, USA
| | - Matthew J Tyska
- Department of Cell and Developmental Biology, Vanderbilt University, Nashville, Tennessee, USA.
| |
Collapse
|
11
|
Miller WB, Baluška F, Torday JS. Cellular senomic measurements in Cognition-Based Evolution. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2020; 156:20-33. [PMID: 32738355 DOI: 10.1016/j.pbiomolbio.2020.07.002] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/08/2019] [Revised: 02/20/2020] [Accepted: 07/04/2020] [Indexed: 12/27/2022]
Abstract
All living entities are cognitive and dependent on ambiguous information. Any assessment of that imprecision is necessarily a measuring function. Individual cells measure information to sustain self-referential homeostatic equipoise (self-identity) in juxtaposition to the external environment. The validity of that information is improved by its collective assessment. The reception of cellular information obliges thermodynamic reactions that initiate a self-reinforcing work channel. This expresses as natural cellular engineering and niche constructions which become the complex interrelated tissue ecologies of holobionts. Multicellularity is collaborative cellular information management directed towards the optimization of information quality through its collective measured assessment. Biology and its evolution can now be re-framed as the continuous process of self-referential cellular measurement in the perpetual defense of individual cellular self-identities through the collective form.
Collapse
Affiliation(s)
| | | | - John S Torday
- Department of Pediatrics, Harbor-UCLA Medical Center, USA.
| |
Collapse
|
12
|
Wesley CC, Mishra S, Levy DL. Organelle size scaling over embryonic development. WILEY INTERDISCIPLINARY REVIEWS-DEVELOPMENTAL BIOLOGY 2020; 9:e376. [PMID: 32003549 DOI: 10.1002/wdev.376] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/26/2019] [Revised: 12/19/2019] [Accepted: 01/08/2020] [Indexed: 12/13/2022]
Abstract
Cell division without growth results in progressive cell size reductions during early embryonic development. How do the sizes of intracellular structures and organelles scale with cell size and what are the functional implications of such scaling relationships? Model organisms, in particular Caenorhabditis elegans worms, Drosophila melanogaster flies, Xenopus laevis frogs, and Mus musculus mice, have provided insights into developmental size scaling of the nucleus, mitotic spindle, and chromosomes. Nuclear size is regulated by nucleocytoplasmic transport, nuclear envelope proteins, and the cytoskeleton. Regulators of microtubule dynamics and chromatin compaction modulate spindle and mitotic chromosome size scaling, respectively. Developmental scaling relationships for membrane-bound organelles, like the endoplasmic reticulum, Golgi, mitochondria, and lysosomes, have been less studied, although new imaging approaches promise to rectify this deficiency. While models that invoke limiting components and dynamic regulation of assembly and disassembly can account for some size scaling relationships in early embryos, it will be exciting to investigate the contribution of newer concepts in cell biology such as phase separation and interorganellar contacts. With a growing understanding of the underlying mechanisms of organelle size scaling, future studies promise to uncover the significance of proper scaling for cell function and embryonic development, as well as how aberrant scaling contributes to disease. This article is categorized under: Establishment of Spatial and Temporal Patterns > Regulation of Size, Proportion, and Timing Early Embryonic Development > Fertilization to Gastrulation Comparative Development and Evolution > Model Systems.
Collapse
Affiliation(s)
- Chase C Wesley
- Department of Molecular Biology, University of Wyoming, Laramie, Wyoming
| | - Sampada Mishra
- Department of Molecular Biology, University of Wyoming, Laramie, Wyoming
| | - Daniel L Levy
- Department of Molecular Biology, University of Wyoming, Laramie, Wyoming
| |
Collapse
|
13
|
Double Tubular Contractile Structure of the Type VI Secretion System Displays Striking Flexibility and Elasticity. J Bacteriol 2019; 202:JB.00425-19. [PMID: 31636107 DOI: 10.1128/jb.00425-19] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2019] [Accepted: 10/14/2019] [Indexed: 12/22/2022] Open
Abstract
Antimicrobial treatment can induce many bacterial pathogens to enter a cell wall-deficient state that contributes to persistent infections. The effect of this physiological state on the assembly of transenvelope-anchored organelles is not well understood. The type VI secretion system (T6SS) is a widespread molecular weapon for interspecies interactions and virulence, comprising a long double tubular structure and a transenvelope/baseplate complex. Here, we report that cell wall-deficient spheroplasts assembled highly flexible and elastic T6SS structures forming U, O, or S shapes. Upon contacting the inner membrane, the T6SS tubes did not contract but rather continued to grow along the membrane. Such deformation likely results from continual addition of sheath/tube subunits at the distal end. Induction of TagA repressed curved sheath formation. Curved sheaths could also contract and deliver T6SS substrates and were readily disassembled by the ClpV ATPase after contraction. Our data highlight the dramatic effect of cell wall deficiency on the shape of the T6SS structures and reveal the elastic nature of this double tubular contractile injection nanomachine.IMPORTANCE The cell wall is a physical scaffold that all transenvelope complexes have to cross for assembly. However, the cell wall-deficient state has been described as a common condition found in both Gram-negative and Gram-positive pathogens during persistent infections. Loss of cell wall is known to have pleiotropic physiological effects, but how membrane-anchored large cellular organelles adapt to this unique state is less completely understood. Our study examined the assembly of the T6SS in cell wall-deficient spheroplast cells. We report the elastic nature of contractile T6SS tubules under such conditions, providing key insights for understanding how large intracellular structures such as the T6SS accommodate the multifaceted changes in cell wall-deficient cells.
Collapse
|
14
|
Miller WB, Torday JS, Baluška F. The N-space Episenome unifies cellular information space-time within cognition-based evolution. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2019; 150:112-139. [PMID: 31415772 DOI: 10.1016/j.pbiomolbio.2019.08.006] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/13/2019] [Revised: 07/26/2019] [Accepted: 08/09/2019] [Indexed: 02/08/2023]
Abstract
Self-referential cellular homeostasis is maintained by the measured assessment of both internal status and external conditions based within an integrated cellular information field. This cellular field attachment to biologic information space-time coordinates environmental inputs by connecting the cellular senome, as the sum of the sensory experiences of the cell, with its genome and epigenome. In multicellular organisms, individual cellular information fields aggregate into a collective information architectural matrix, termed a N-space Episenome, that enables mutualized organism-wide information management. It is hypothesized that biological organization represents a dual heritable system constituted by both its biological materiality and a conjoining N-space Episenome. It is further proposed that morphogenesis derives from reciprocations between these inter-related facets to yield coordinated multicellular growth and development. The N-space Episenome is conceived as a whole cell informational projection that is heritable, transferable via cell division and essential for the synchronous integration of the diverse self-referential cells that constitute holobionts.
Collapse
Affiliation(s)
| | - John S Torday
- Department of Pediatrics, Harbor-UCLA Medical Center, USA.
| | | |
Collapse
|
15
|
Zhao X, Chen Y, Niu G, Gu D, Wang J, Cao Y, Yin Y, Li X, Ding D, Xi R, Meng M. Photostable pH-Sensitive Near-Infrared Aggregation-Induced Emission Luminogen for Long-Term Mitochondrial Tracking. ACS APPLIED MATERIALS & INTERFACES 2019; 11:13134-13139. [PMID: 30901189 DOI: 10.1021/acsami.9b02228] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Mitochondria are crucial in the process of oxidative metabolism and apoptosis. Their morphology is greatly associated with the development of certain diseases. For specific and long-term imaging of mitochondrial morphology, we synthesized a new mitochondria-targeted near-infrared (NIR) fluorescent probe (TPE-Xan-In) by incorporating TPE with a NIR merocyanine skeleton (Xan-In). TPE-Xan-In displayed both absorption (660 nm) and emission peaks (743 nm) in the NIR region. Moreover, it showed aggregation-induced emission properties at neutral pH and specifically illuminated mitochondria with good biocompatibility, superior photostability, and high tolerance to mitochondrial membrane potential changes. With a pH-responsive unit, hydroxyl xanthene (Xan), the probe exhibited a pH-sensitive fluorescence emission in the range of pH 4.0-7.0, which indicated its potential in long-term tracking of pH and morphology changes of mitochondria in the biomedical research studies.
Collapse
Affiliation(s)
- Xiujie Zhao
- College of Pharmacy, State Key Laboratory of Medicinal Chemical Biology and Tianjin Key Laboratory of Molecular Drug Research , Nankai University , Tianjin 300353 , China
| | - Yun Chen
- College of Pharmacy, State Key Laboratory of Medicinal Chemical Biology and Tianjin Key Laboratory of Molecular Drug Research , Nankai University , Tianjin 300353 , China
| | - Guiyu Niu
- College of Pharmacy, State Key Laboratory of Medicinal Chemical Biology and Tianjin Key Laboratory of Molecular Drug Research , Nankai University , Tianjin 300353 , China
| | - Dening Gu
- College of Pharmacy, State Key Laboratory of Medicinal Chemical Biology and Tianjin Key Laboratory of Molecular Drug Research , Nankai University , Tianjin 300353 , China
| | - Jianning Wang
- College of Pharmacy, State Key Laboratory of Medicinal Chemical Biology and Tianjin Key Laboratory of Molecular Drug Research , Nankai University , Tianjin 300353 , China
| | - Yanmei Cao
- College of Pharmacy, State Key Laboratory of Medicinal Chemical Biology and Tianjin Key Laboratory of Molecular Drug Research , Nankai University , Tianjin 300353 , China
| | - Yongmei Yin
- College of Pharmacy, State Key Laboratory of Medicinal Chemical Biology and Tianjin Key Laboratory of Molecular Drug Research , Nankai University , Tianjin 300353 , China
| | - Xiaogang Li
- Peking Union Medical College Hospital , Peking Union Medical College and Chinese Academy of Medical Sciences , Beijing 100730 , China
| | - Dan Ding
- State Key Laboratory of Medicinal Chemical Biology, Key Laboratory of Bioactive Materials, Ministry of Education, and College of Life Sciences , Nankai University , Tianjin 300071 , China
| | - Rimo Xi
- College of Pharmacy, State Key Laboratory of Medicinal Chemical Biology and Tianjin Key Laboratory of Molecular Drug Research , Nankai University , Tianjin 300353 , China
| | - Meng Meng
- College of Pharmacy, State Key Laboratory of Medicinal Chemical Biology and Tianjin Key Laboratory of Molecular Drug Research , Nankai University , Tianjin 300353 , China
| |
Collapse
|
16
|
Lacroix B, Letort G, Pitayu L, Sallé J, Stefanutti M, Maton G, Ladouceur AM, Canman JC, Maddox PS, Maddox AS, Minc N, Nédélec F, Dumont J. Microtubule Dynamics Scale with Cell Size to Set Spindle Length and Assembly Timing. Dev Cell 2018; 45:496-511.e6. [PMID: 29787710 DOI: 10.1016/j.devcel.2018.04.022] [Citation(s) in RCA: 57] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2017] [Revised: 03/22/2018] [Accepted: 04/24/2018] [Indexed: 12/22/2022]
Abstract
Successive cell divisions during embryonic cleavage create increasingly smaller cells, so intracellular structures must adapt accordingly. Mitotic spindle size correlates with cell size, but the mechanisms for this scaling remain unclear. Using live cell imaging, we analyzed spindle scaling during embryo cleavage in the nematode Caenorhabditis elegans and sea urchin Paracentrotus lividus. We reveal a common scaling mechanism, where the growth rate of spindle microtubules scales with cell volume, which explains spindle shortening. Spindle assembly timing is, however, constant throughout successive divisions. Analyses in silico suggest that controlling the microtubule growth rate is sufficient to scale spindle length and maintain a constant assembly timing. We tested our in silico predictions to demonstrate that modulating cell volume or microtubule growth rate in vivo induces a proportional spindle size change. Our results suggest that scalability of the microtubule growth rate when cell size varies adapts spindle length to cell volume.
Collapse
Affiliation(s)
- Benjamin Lacroix
- Institut Jacques Monod, CNRS, UMR 7592, University Paris Diderot, Sorbonne Paris Cité, 75205 Paris, France.
| | - Gaëlle Letort
- Institut Curie, Mines Paris Tech, Inserm, U900, PSL Research University, 75005 Paris, France
| | - Laras Pitayu
- Institut Jacques Monod, CNRS, UMR 7592, University Paris Diderot, Sorbonne Paris Cité, 75205 Paris, France
| | - Jérémy Sallé
- Institut Jacques Monod, CNRS, UMR 7592, University Paris Diderot, Sorbonne Paris Cité, 75205 Paris, France
| | - Marine Stefanutti
- Institut Jacques Monod, CNRS, UMR 7592, University Paris Diderot, Sorbonne Paris Cité, 75205 Paris, France
| | - Gilliane Maton
- Institut Jacques Monod, CNRS, UMR 7592, University Paris Diderot, Sorbonne Paris Cité, 75205 Paris, France
| | | | - Julie C Canman
- Columbia University Medical Center, Department of Pathology and Cell Biology, New York, NY 10032, USA
| | - Paul S Maddox
- Department of Biology, University of North Carolina, Chapel Hill, NC 27599, USA
| | - Amy S Maddox
- Department of Biology, University of North Carolina, Chapel Hill, NC 27599, USA
| | - Nicolas Minc
- Institut Jacques Monod, CNRS, UMR 7592, University Paris Diderot, Sorbonne Paris Cité, 75205 Paris, France
| | - François Nédélec
- Cell Biology and Biophysics Unit, European Molecular Biology Laboratory, 69117 Heidelberg, Germany.
| | - Julien Dumont
- Institut Jacques Monod, CNRS, UMR 7592, University Paris Diderot, Sorbonne Paris Cité, 75205 Paris, France.
| |
Collapse
|
17
|
McLachlan IG, Beets I, de Bono M, Heiman MG. A neuronal MAP kinase constrains growth of a Caenorhabditis elegans sensory dendrite throughout the life of the organism. PLoS Genet 2018; 14:e1007435. [PMID: 29879119 PMCID: PMC6007932 DOI: 10.1371/journal.pgen.1007435] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2017] [Revised: 06/19/2018] [Accepted: 05/18/2018] [Indexed: 02/07/2023] Open
Abstract
Neurons develop elaborate morphologies that provide a model for understanding cellular architecture. By studying C. elegans sensory dendrites, we previously identified genes that act to promote the extension of ciliated sensory dendrites during embryogenesis. Interestingly, the nonciliated dendrite of the oxygen-sensing neuron URX is not affected by these genes, suggesting it develops through a distinct mechanism. Here, we use a visual forward genetic screen to identify mutants that affect URX dendrite morphogenesis. We find that disruption of the MAP kinase MAPK-15 or the βH-spectrin SMA-1 causes a phenotype opposite to what we had seen before: dendrites extend normally during embryogenesis but begin to overgrow as the animals reach adulthood, ultimately extending up to 150% of their normal length. SMA-1 is broadly expressed and acts non-cell-autonomously, while MAPK-15 is expressed in many sensory neurons including URX and acts cell-autonomously. MAPK-15 acts at the time of overgrowth, localizes at the dendrite ending, and requires its kinase activity, suggesting it acts locally in time and space to constrain dendrite growth. Finally, we find that the oxygen-sensing guanylate cyclase GCY-35, which normally localizes at the dendrite ending, is localized throughout the overgrown region, and that overgrowth can be suppressed by overexpressing GCY-35 or by genetically mimicking elevated cGMP signaling. These results suggest that overgrowth may correspond to expansion of a sensory compartment at the dendrite ending, reminiscent of the remodeling of sensory cilia or dendritic spines. Thus, in contrast to established pathways that promote dendrite growth during early development, our results reveal a distinct mechanism that constrains dendrite growth throughout the life of the animal, possibly by controlling the size of a sensory compartment at the dendrite ending.
Collapse
Affiliation(s)
- Ian G McLachlan
- Department of Genetics, Harvard Medical School and Boston Children's Hospital, Boston MA, United States of America
| | - Isabel Beets
- Division of Cell Biology, Medical Research Council Laboratory of Molecular Biology, Cambridge, United Kingdom
| | - Mario de Bono
- Division of Cell Biology, Medical Research Council Laboratory of Molecular Biology, Cambridge, United Kingdom
| | - Maxwell G Heiman
- Department of Genetics, Harvard Medical School and Boston Children's Hospital, Boston MA, United States of America
| |
Collapse
|
18
|
Aydogan MG, Wainman A, Saurya S, Steinacker TL, Caballe A, Novak ZA, Baumbach J, Muschalik N, Raff JW. A homeostatic clock sets daughter centriole size in flies. J Cell Biol 2018; 217:1233-1248. [PMID: 29500190 PMCID: PMC5881511 DOI: 10.1083/jcb.201801014] [Citation(s) in RCA: 47] [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: 01/03/2018] [Revised: 01/23/2018] [Accepted: 01/26/2018] [Indexed: 12/13/2022] Open
Abstract
Centrioles are highly structured organelles whose size is remarkably consistent within any given cell type. New centrioles are born when Polo-like kinase 4 (Plk4) recruits Ana2/STIL and Sas-6 to the side of an existing "mother" centriole. These two proteins then assemble into a cartwheel, which grows outwards to form the structural core of a new daughter. Here, we show that in early Drosophila melanogaster embryos, daughter centrioles grow at a linear rate during early S-phase and abruptly stop growing when they reach their correct size in mid- to late S-phase. Unexpectedly, the cartwheel grows from its proximal end, and Plk4 determines both the rate and period of centriole growth: the more active the centriolar Plk4, the faster centrioles grow, but the faster centriolar Plk4 is inactivated and growth ceases. Thus, Plk4 functions as a homeostatic clock, establishing an inverse relationship between growth rate and period to ensure that daughter centrioles grow to the correct size.
Collapse
Affiliation(s)
- Mustafa G Aydogan
- Sir William Dunn School of Pathology, University of Oxford, Oxford, England, UK
| | - Alan Wainman
- Sir William Dunn School of Pathology, University of Oxford, Oxford, England, UK
- Micron Oxford Advanced Bioimaging Unit, Department of Biochemistry, University of Oxford, Oxford, England, UK
| | - Saroj Saurya
- Sir William Dunn School of Pathology, University of Oxford, Oxford, England, UK
| | - Thomas L Steinacker
- Sir William Dunn School of Pathology, University of Oxford, Oxford, England, UK
| | - Anna Caballe
- Sir William Dunn School of Pathology, University of Oxford, Oxford, England, UK
| | - Zsofia A Novak
- Sir William Dunn School of Pathology, University of Oxford, Oxford, England, UK
| | - Janina Baumbach
- Sir William Dunn School of Pathology, University of Oxford, Oxford, England, UK
| | - Nadine Muschalik
- Sir William Dunn School of Pathology, University of Oxford, Oxford, England, UK
| | - Jordan W Raff
- Sir William Dunn School of Pathology, University of Oxford, Oxford, England, UK
| |
Collapse
|
19
|
Banterle N, Gönczy P. Centriole Biogenesis: From Identifying the Characters to Understanding the Plot. Annu Rev Cell Dev Biol 2017; 33:23-49. [PMID: 28813178 DOI: 10.1146/annurev-cellbio-100616-060454] [Citation(s) in RCA: 67] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The centriole is a beautiful microtubule-based organelle that is critical for the proper execution of many fundamental cellular processes, including polarity, motility, and division. Centriole biogenesis, the making of this miniature architectural wonder, has emerged as an exemplary model to dissect the mechanisms governing the assembly of a eukaryotic organelle. Centriole biogenesis relies on a set of core proteins whose contributions to the assembly process have begun to be elucidated. Here, we review current knowledge regarding the mechanisms by which these core characters function in an orderly fashion to assemble the centriole. In particular, we discuss how having the correct proteins at the right place and at the right time is critical to first scaffold, then initiate, and finally execute the centriole assembly process, thus underscoring fundamental principles governing organelle biogenesis.
Collapse
Affiliation(s)
- Niccolò Banterle
- Swiss Institute for Experimental Cancer Research (ISREC), School of Life Sciences, Swiss Federal Institute of Technology (EPFL), CH-1015, Lausanne, Switzerland;
| | - Pierre Gönczy
- Swiss Institute for Experimental Cancer Research (ISREC), School of Life Sciences, Swiss Federal Institute of Technology (EPFL), CH-1015, Lausanne, Switzerland;
| |
Collapse
|
20
|
Spencer AK, Schaumberg AJ, Zallen JA. Scaling of cytoskeletal organization with cell size in Drosophila. Mol Biol Cell 2017; 28:1519-1529. [PMID: 28404752 PMCID: PMC5449150 DOI: 10.1091/mbc.e16-10-0691] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2016] [Revised: 03/31/2017] [Accepted: 04/05/2017] [Indexed: 11/11/2022] Open
Abstract
Actin-rich denticle precursors are regularly distributed in the Drosophila embryo. Cytoskeletal scaling occurs through changes in denticle number and spacing. Denticle spacing scales with cell length over a 10-fold range. Accurate denticle positioning requires the microtubule cytoskeleton. Spatially organized macromolecular complexes are essential for cell and tissue function, but the mechanisms that organize micron-scale structures within cells are not well understood. Microtubule-based structures such as mitotic spindles scale with cell size, but less is known about the scaling of actin structures within cells. Actin-rich denticle precursors cover the ventral surface of the Drosophila embryo and larva and provide templates for cuticular structures involved in larval locomotion. Using quantitative imaging and statistical modeling, we demonstrate that denticle number and spacing scale with cell length over a wide range of cell sizes in embryos and larvae. Denticle number and spacing are reduced under space-limited conditions, and both features robustly scale over a 10-fold increase in cell length during larval growth. We show that the relationship between cell length and denticle spacing can be recapitulated by specific mathematical equations in embryos and larvae and that accurate denticle spacing requires an intact microtubule network and the microtubule minus end–binding protein, Patronin. These results identify a novel mechanism of microtubule-dependent actin scaling that maintains precise patterns of actin organization during tissue growth.
Collapse
Affiliation(s)
- Alison K Spencer
- Gerstner Sloan Kettering Graduate School of Biomedical Sciences.,Howard Hughes Medical Institute and Developmental Biology Program, Sloan Kettering Institute, Memorial Sloan Kettering Cancer Center, New York, NY 10065
| | - Andrew J Schaumberg
- Weill Cornell Graduate School of Medical Sciences and the Tri-Institutional PhD Program in Computational Biology and Medicine, Memorial Sloan Kettering Cancer Center, New York, NY 10065
| | - Jennifer A Zallen
- Howard Hughes Medical Institute and Developmental Biology Program, Sloan Kettering Institute, Memorial Sloan Kettering Cancer Center, New York, NY 10065
| |
Collapse
|
21
|
Lechtreck KF, Van De Weghe JC, Harris JA, Liu P. Protein transport in growing and steady-state cilia. Traffic 2017; 18:277-286. [PMID: 28248449 DOI: 10.1111/tra.12474] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2016] [Revised: 02/22/2017] [Accepted: 02/22/2017] [Indexed: 12/18/2022]
Abstract
Cilia and eukaryotic flagella are threadlike cell extensions with motile and sensory functions. Their assembly requires intraflagellar transport (IFT), a bidirectional motor-driven transport of protein carriers along the axonemal microtubules. IFT moves ample amounts of structural proteins including tubulin into growing cilia likely explaining its critical role for assembly. IFT continues in non-growing cilia contributing to a variety of processes ranging from axonemal maintenance and the export of non-ciliary proteins to cell locomotion and ciliary signaling. Here, we discuss recent data on cues regulating the type, amount and timing of cargo transported by IFT. A regulation of IFT-cargo interactions is critical to establish, maintain and adjust ciliary length, protein composition and function.
Collapse
Affiliation(s)
- Karl F Lechtreck
- Department of Cellular Biology, University of Georgia, Athens, Georgia
| | | | | | - Peiwei Liu
- Department of Cellular Biology, University of Georgia, Athens, Georgia
| |
Collapse
|
22
|
Mitochondrial Function and Cell Size: An Allometric Relationship. Trends Cell Biol 2017; 27:393-402. [PMID: 28284466 DOI: 10.1016/j.tcb.2017.02.006] [Citation(s) in RCA: 75] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2016] [Revised: 02/08/2017] [Accepted: 02/15/2017] [Indexed: 01/09/2023]
Abstract
Allometric scaling of metabolic rate results in lower total mitochondrial oxygen consumption with increasing organismal size. This is considered a universal law in biology. Here, we discuss how allometric laws impose size-dependent limits to mitochondrial activity at the cellular level. This cell-size-dependent mitochondrial metabolic activity results in nonlinear scaling of metabolism in proliferating cells, which can explain size homeostasis. The allometry in mitochondrial activity can be controlled through mitochondrial fusion and fission machinery, suggesting that mitochondrial connectivity can bypass transport limitations, the presumed biophysical basis for allometry. As physical size affects cellular functionality, cell-size-dependent metabolism becomes directly relevant for development, metabolic diseases, and aging.
Collapse
|
23
|
Ba Q, Yang G. Intracellular organelle networks: Understanding their organization and communication through systems-level modeling and analysis. ACTA ACUST UNITED AC 2017. [DOI: 10.1007/s11515-016-1436-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
|
24
|
Abstract
In this review we discuss the history and the current state of ideas related to the mechanism of size regulation of the thick (myosin) and thin (actin) filaments in vertebrate striated muscles. Various hypotheses have been considered during of more than half century of research, recently mostly involving titin and nebulin acting as templates or 'molecular rulers', terminating exact assembly. These two giant, single-polypeptide, filamentous proteins are bound in situ along the thick and thin filaments, respectively, with an almost perfect match in the respective lengths and structural periodicities. However, evidence still questions the possibility that the proteins function as templates, or scaffolds, on which the thin and thick filaments could be assembled. In addition, the progress in muscle research during the last decades highlighted a number of other factors that could potentially be involved in the mechanism of length regulation: molecular chaperones that may guide folding and assembly of actin and myosin; capping proteins that can influence the rates of assembly-disassembly of the myofilaments; Ca2+ transients that can activate or deactivate protein interactions, etc. The entire mechanism of sarcomere assembly appears complex and highly dynamic. This mechanism is also capable of producing filaments of about the correct size without titin and nebulin. What then is the role of these proteins? Evidence points to titin and nebulin stabilizing structures of the respective filaments. This stabilizing effect, based on linear proteins of a fixed size, implies that titin and nebulin are indeed molecular rulers of the filaments. Although the proteins may not function as templates in the assembly of the filaments, they measure and stabilize exactly the same size of the functionally important for the muscles segments in each of the respective filaments.
Collapse
|
25
|
Wang YF, Zhang T, Liang XJ. Aggregation-Induced Emission: Lighting up Cells, Revealing Life! SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2016; 12:6451-6477. [PMID: 27592595 DOI: 10.1002/smll.201601468] [Citation(s) in RCA: 78] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/29/2016] [Revised: 06/30/2016] [Indexed: 06/06/2023]
Abstract
Understanding metabolism and dynamic biological events in cells, as well as physiological functions and pathological changes in organisms, is the major goal of biological investigations. It will improve our capability to diagnose and treat diseases, and will enhance personalized medicine. Fluorescence imaging is a powerful tool that plays an essential role in acquiring the comprehensive knowledge necessary to help reach this goal. Fluorescent molecules are crucial factors for obtaining high quality images. In contrast to conventional fluorogens with aggregation-caused quenching (ACQ) effect, molecules that show aggregation-induced emission (AIE) effect open up new avenues for fluorescence imaging. So far, a large variety of AIE probes have been developed and applied to bioimaging because of their outstanding characteristics, such as high fluorescence efficiency, excellent photostability and high signal-to-noise ratio (SNR). In this review, recent advances in AIE-based probes for biomedical imaging of intracellular microenvironments, natural macromolecules, subcellular organelles, intracellular processes, living tissues, and diagnosis and therapeutic evaluation of diseases in vivo are summarized. It is hoped that this review generates great research enthusiasm for AIE-based bioimaging, in order to promote the development of promising AIE probes and guide us to a better understanding of the biological essence of life.
Collapse
Affiliation(s)
- Yi-Feng Wang
- CAS Center for Excellence in Nanoscience, CAS Key Laboratory for Biomedical Effects of Nanomaterials & Nanosafety, Laboratory of Controllable Nanopharmaceuticals, National Center for Nanoscience and Technology of China, Beijing, 100190, P. R. China
- University of Chinese Academy of Sciences, Beijing, 100049, P. R. China
| | - Tingbin Zhang
- CAS Center for Excellence in Nanoscience, CAS Key Laboratory for Biomedical Effects of Nanomaterials & Nanosafety, Laboratory of Controllable Nanopharmaceuticals, National Center for Nanoscience and Technology of China, Beijing, 100190, P. R. China
- School of Chemical Engineering and Technology, Tianjin University, Tianjin, 300072, P. R. China
| | - Xing-Jie Liang
- CAS Center for Excellence in Nanoscience, CAS Key Laboratory for Biomedical Effects of Nanomaterials & Nanosafety, Laboratory of Controllable Nanopharmaceuticals, National Center for Nanoscience and Technology of China, Beijing, 100190, P. R. China
- University of Chinese Academy of Sciences, Beijing, 100049, P. R. China
| |
Collapse
|
26
|
Zhang J, Ferré-DAmaré AR. Trying on tRNA for Size: RNase P and the T-box Riboswitch as Molecular Rulers. Biomolecules 2016; 6:biom6020018. [PMID: 27043647 PMCID: PMC4919913 DOI: 10.3390/biom6020018] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2016] [Revised: 03/23/2016] [Accepted: 03/25/2016] [Indexed: 12/27/2022] Open
Abstract
Length determination is a fundamental problem in biology and chemistry. Numerous proteins measure distances on linear biopolymers to exert effects with remarkable spatial precision. Recently, ruler-like devices made of noncoding RNAs have been structurally and biochemically characterized. Two prominent examples are the RNase P ribozyme and the T-box riboswitch. Both act as molecular calipers. The two RNAs clamp onto the elbow of tRNA (or pre-tRNA) and make distance measurements orthogonal to each other. Here, we compare and contrast the molecular ruler characteristics of these RNAs. RNase P appears pre-configured to measure a fixed distance on pre-tRNA to ensure the fidelity of its maturation. RNase P is a multiple-turnover ribozyme, and its rigid structure efficiently selects pre-tRNAs, cleaves, and releases them. In contrast, the T-box is flexible and segmented, an architecture that adapts to the intrinsically flexible tRNA. The tripartite T-box inspects the overall shape, anticodon sequence, and aminoacylation status of an incoming tRNA while it folds co-transcriptionally, leading to a singular, conditional genetic switching event. The elucidation of the structures and mechanisms of action of these two RNA molecular rulers may augur the discovery of new RNA measuring devices in noncoding and viral transcriptomes, and inform the design of artificial RNA rulers.
Collapse
Affiliation(s)
- Jinwei Zhang
- Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, 50 South Drive, Bethesda, MD 20892, USA.
| | - Adrian R Ferré-DAmaré
- Laboratory of RNA Biophysics and Cellular Physiology, National Heart, Lung and Blood Institute, 50 South Drive, Bethesda, MD 20892, USA.
| |
Collapse
|