1
|
Chai Y, Qi K, Wu Y, Li D, Tan G, Guo Y, Chu J, Mu Y, Shen C, Wen Q. All-optical interrogation of brain-wide activity in freely swimming larval zebrafish. iScience 2024; 27:108385. [PMID: 38205255 PMCID: PMC10776927 DOI: 10.1016/j.isci.2023.108385] [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] [Received: 06/12/2023] [Revised: 09/22/2023] [Accepted: 10/30/2023] [Indexed: 01/12/2024] Open
Abstract
We introduce an all-optical technique that enables volumetric imaging of brain-wide calcium activity and targeted optogenetic stimulation of specific brain regions in unrestrained larval zebrafish. The system consists of three main components: a 3D tracking module, a dual-color fluorescence imaging module, and a real-time activity manipulation module. Our approach uses a sensitive genetically encoded calcium indicator in combination with a long Stokes shift red fluorescence protein as a reference channel, allowing the extraction of Ca2+ activity from signals contaminated by motion artifacts. The method also incorporates rapid 3D image reconstruction and registration, facilitating real-time selective optogenetic stimulation of different regions of the brain. By demonstrating that selective light activation of the midbrain regions in larval zebrafish could reliably trigger biased turning behavior and changes of brain-wide neural activity, we present a valuable tool for investigating the causal relationship between distributed neural circuit dynamics and naturalistic behavior.
Collapse
Affiliation(s)
- Yuming Chai
- Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, China
- Hefei National Research Center for Physical Sciences at the Microscale, Center for Integrative Imaging, University of Science and Technology of China, Hefei, China
| | - Kexin Qi
- Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, China
- Hefei National Research Center for Physical Sciences at the Microscale, Center for Integrative Imaging, University of Science and Technology of China, Hefei, China
| | - Yubin Wu
- Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, China
- Hefei National Research Center for Physical Sciences at the Microscale, Center for Integrative Imaging, University of Science and Technology of China, Hefei, China
| | - Daguang Li
- Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, China
- Hefei National Research Center for Physical Sciences at the Microscale, Center for Integrative Imaging, University of Science and Technology of China, Hefei, China
| | - Guodong Tan
- Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, China
- Hefei National Research Center for Physical Sciences at the Microscale, Center for Integrative Imaging, University of Science and Technology of China, Hefei, China
| | - Yuqi Guo
- Guangdong Provincial Key Laboratory of Biomedical Optical Imaging Technology and Center for Biomedical Optics and Molecular Imaging, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen, China
| | - Jun Chu
- Guangdong Provincial Key Laboratory of Biomedical Optical Imaging Technology and Center for Biomedical Optics and Molecular Imaging, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen, China
| | - Yu Mu
- Institute of Neuroscience, State Key Laboratory of Neuroscience, Center for Excellence in Brain Science and Intelligence Technology, Chinese Academy of Sciences, Shanghai, China
| | - Chen Shen
- Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, China
- Hefei National Research Center for Physical Sciences at the Microscale, Center for Integrative Imaging, University of Science and Technology of China, Hefei, China
| | - Quan Wen
- Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, China
- Hefei National Research Center for Physical Sciences at the Microscale, Center for Integrative Imaging, University of Science and Technology of China, Hefei, China
| |
Collapse
|
2
|
Sun H, Beets I, Schafer W, Hobert O. Comparing engineered nuclear-localized reporter cassettes. MICROPUBLICATION BIOLOGY 2023; 2023:10.17912/micropub.biology.001014. [PMID: 38021170 PMCID: PMC10654776 DOI: 10.17912/micropub.biology.001014] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Figures] [Subscribe] [Scholar Register] [Received: 10/03/2023] [Revised: 10/25/2023] [Accepted: 10/30/2023] [Indexed: 12/01/2023]
Abstract
Recent single-cell transcriptome analysis has revealed a tremendous breadth and specificity of neuropeptide-encoding gene expression in the nervous system of C. elegans. To analyze the dynamics of neuropeptide gene expression, as well as to dissect the regulatory mechanism by which their expression is controlled, reporter genes remain an important tool. Using CRISPR/Cas9 genome-engineering, we generate here reporter alleles for 6 different neuropeptide encoding genes (3 flp genes, 1 nlp and 2 insulin genes). We find that different reporter cassettes result in different levels of reporter expression and recommend usage of an SL2::GFP::H2B or GFP::H2B::SL2 cassette.
Collapse
Affiliation(s)
- HaoSheng Sun
- Cell, Developmental and Integrative Biology, University of Alabama at Birmingham, Birmingham, Alabama, United States
- Howard Hughes Medical Institute, Chevy Chase, Maryland, United States
| | - Isabel Beets
- Division of Animal Physiology and Neurobiology, KU Leuven, Leuven, Flanders, Belgium
| | - William Schafer
- Division of Animal Physiology and Neurobiology, KU Leuven, Leuven, Flanders, Belgium
- Neurobiology division, MRC Laboratory of Molecular Biology, Cambridge, England, United Kingdom
| | - Oliver Hobert
- Howard Hughes Medical Institute, Chevy Chase, Maryland, United States
- Biological Sciences, Columbia University, New York, New York, United States
| |
Collapse
|
3
|
Ding J, Peng L, Moon S, Lee HJ, Patel DS, Lu H. An expanded GCaMP reporter toolkit for functional imaging in Caenorhabditis elegans. G3 (BETHESDA, MD.) 2023; 13:jkad183. [PMID: 37565483 PMCID: PMC10542313 DOI: 10.1093/g3journal/jkad183] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/10/2023] [Accepted: 07/16/2023] [Indexed: 08/12/2023]
Abstract
In living organisms, changes in calcium flux are integral to many different cellular functions and are especially critical for the activity of neurons and myocytes. Genetically encoded calcium indicators (GECIs) have been popular tools for reporting changes in calcium levels in vivo. In particular, GCaMPs, derived from GFP, are the most widely used GECIs and have become an invaluable toolkit for neurophysiological studies. Recently, new variants of GCaMP, which offer a greater variety of temporal dynamics and improved brightness, have been developed. However, these variants are not readily available to the Caenorhabditis elegans research community. This work reports a set of GCaMP6 and jGCaMP7 reporters optimized for C. elegans studies. Our toolkit provides reporters with improved dynamic range, varied kinetics, and targeted subcellular localizations. Besides optimized routine uses, this set of reporters is also well suited for studies requiring fast imaging speeds and low magnification or low-cost platforms.
Collapse
Affiliation(s)
- Jimmy Ding
- Interdisciplinary Bioengineering Graduate Program, Georgia Institute of Technology, Atlanta, GA 30332, USA
| | - Lucinda Peng
- Interdisciplinary Bioengineering Graduate Program, Georgia Institute of Technology, Atlanta, GA 30332, USA
| | - Sihoon Moon
- School of Chemical & Biomolecular Engineering, Georgia Institute of Technology, Atlanta, GA 30332, USA
| | - Hyun Jee Lee
- School of Chemical & Biomolecular Engineering, Georgia Institute of Technology, Atlanta, GA 30332, USA
| | - Dhaval S Patel
- School of Chemical & Biomolecular Engineering, Georgia Institute of Technology, Atlanta, GA 30332, USA
| | - Hang Lu
- Interdisciplinary Bioengineering Graduate Program, Georgia Institute of Technology, Atlanta, GA 30332, USA
- School of Chemical & Biomolecular Engineering, Georgia Institute of Technology, Atlanta, GA 30332, USA
| |
Collapse
|
4
|
Stevenson ZC, Moerdyk-Schauwecker MJ, Banse SA, Patel DS, Lu H, Phillips PC. High-throughput library transgenesis in Caenorhabditis elegans via Transgenic Arrays Resulting in Diversity of Integrated Sequences (TARDIS). eLife 2023; 12:RP84831. [PMID: 37401921 PMCID: PMC10328503 DOI: 10.7554/elife.84831] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/05/2023] Open
Abstract
High-throughput transgenesis using synthetic DNA libraries is a powerful method for systematically exploring genetic function. Diverse synthesized libraries have been used for protein engineering, identification of protein-protein interactions, characterization of promoter libraries, developmental and evolutionary lineage tracking, and various other exploratory assays. However, the need for library transgenesis has effectively restricted these approaches to single-cell models. Here, we present Transgenic Arrays Resulting in Diversity of Integrated Sequences (TARDIS), a simple yet powerful approach to large-scale transgenesis that overcomes typical limitations encountered in multicellular systems. TARDIS splits the transgenesis process into a two-step process: creation of individuals carrying experimentally introduced sequence libraries, followed by inducible extraction and integration of individual sequences/library components from the larger library cassette into engineered genomic sites. Thus, transformation of a single individual, followed by lineage expansion and functional transgenesis, gives rise to thousands of genetically unique transgenic individuals. We demonstrate the power of this system using engineered, split selectable TARDIS sites in Caenorhabditis elegans to generate (1) a large set of individually barcoded lineages and (2) transcriptional reporter lines from predefined promoter libraries. We find that this approach increases transformation yields up to approximately 1000-fold over current single-step methods. While we demonstrate the utility of TARDIS using C. elegans, in principle the process is adaptable to any system where experimentally generated genomic loci landing pads and diverse, heritable DNA elements can be generated.
Collapse
Affiliation(s)
| | | | - Stephen A Banse
- Institute of Ecology and Evolution, University of OregonEugeneUnited States
| | - Dhaval S Patel
- School of Chemical & Biomolecular Engineering, Georgia Institute of TechnologyAtlantaUnited States
- Petit Institute for Bioengineering and Bioscience, Georgia Institute of TechnologyAtlantaUnited States
| | - Hang Lu
- School of Chemical & Biomolecular Engineering, Georgia Institute of TechnologyAtlantaUnited States
- Petit Institute for Bioengineering and Bioscience, Georgia Institute of TechnologyAtlantaUnited States
| | - Patrick C Phillips
- Institute of Ecology and Evolution, University of OregonEugeneUnited States
| |
Collapse
|
5
|
Ding J, Peng L, Moon S, Lee HJ, Patel DS, Lu H. An expanded GCaMP reporter toolkit for functional imaging in C. elegans. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.03.06.531342. [PMID: 36945463 PMCID: PMC10028802 DOI: 10.1101/2023.03.06.531342] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/12/2023]
Abstract
In living organisms, changes in calcium flux are integral to many different cellular functions and are especially critical for the activity of neurons and myocytes. Genetically encoded calcium indicators (GECIs) have been popular tools for reporting changes in calcium levels in vivo . In particular, GCaMP, derived from GFP, are the most widely used GECIs and have become an invaluable toolkit for neurophysiological studies. Recently, new variants of GCaMP, which offer a greater variety of temporal dynamics and improved brightness, have been developed. However, these variants are not readily available to the Caenorhabditis elegans research community. This work reports a set of GCaMP6 and jGCaMP7 reporters optimized for C. elegans studies. Our toolkit provides reporters with improved dynamic range, varied kinetics, and targeted subcellular localizations. Besides optimized routine uses, this set of reporters are also well-suited for studies requiring fast imaging speeds and low magnification or low-cost platforms.
Collapse
Affiliation(s)
- Jimmy Ding
- These authors contributed equally
- Petit Institute for Bioengineering and Bioscience, Georgia Institute of Technology, Atlanta, GA 30332, USA
| | - Lucinda Peng
- These authors contributed equally
- Petit Institute for Bioengineering and Bioscience, Georgia Institute of Technology, Atlanta, GA 30332, USA
| | - Sihoon Moon
- These authors contributed equally
- School of Chemical & Biomolecular Engineering, Georgia Institute of Technology, Atlanta, GA 30332, USA
| | - Hyun Jee Lee
- These authors contributed equally
- School of Chemical & Biomolecular Engineering, Georgia Institute of Technology, Atlanta, GA 30332, USA
| | - Dhaval S. Patel
- School of Chemical & Biomolecular Engineering, Georgia Institute of Technology, Atlanta, GA 30332, USA
- Present address: NemaLife Inc, Lubbock, TX 79409, USA
| | - Hang Lu
- Petit Institute for Bioengineering and Bioscience, Georgia Institute of Technology, Atlanta, GA 30332, USA
- School of Chemical & Biomolecular Engineering, Georgia Institute of Technology, Atlanta, GA 30332, USA
| |
Collapse
|
6
|
Wong MK, Ho VWS, Huang X, Chan LY, Xie D, Li R, Ren X, Guan G, Ma Y, Hu B, Yan H, Zhao Z. Initial characterization of gap phase introduction in every cell cycle of C. elegans embryogenesis. Front Cell Dev Biol 2022; 10:978962. [PMID: 36393848 PMCID: PMC9641140 DOI: 10.3389/fcell.2022.978962] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2022] [Accepted: 09/20/2022] [Indexed: 11/28/2022] Open
Abstract
Early embryonic cell cycles usually alternate between S and M phases without any gap phase. When the gap phases are developmentally introduced in various cell types remains poorly defined especially during embryogenesis. To establish the cell-specific introduction of gap phases in embryo, we generate multiple fluorescence ubiquitin cell cycle indicators (FUCCI) in C. elegans. Time-lapse 3D imaging followed by lineal expression profiling reveals sharp and differential accumulation of the FUCCI reporters, allowing the systematic demarcation of cell cycle phases throughout embryogenesis. Accumulation of the reporters reliably identifies both G1 and G2 phases only in two embryonic cells with an extended cell cycle length, suggesting that the remaining cells divide either without a G1 phase, or with a brief G1 phase that is too short to be picked up by our reporters. In summary, we provide an initial picture of gap phase introduction in a metazoan embryo. The newly developed FUCCI reporters pave the way for further characterization of developmental control of cell cycle progression.
Collapse
Affiliation(s)
- Ming-Kin Wong
- Department of Biology, Hong Kong Baptist University, Kowloon, Hong Kong SAR, China
| | - Vincy Wing Sze Ho
- Department of Biology, Hong Kong Baptist University, Kowloon, Hong Kong SAR, China
| | - Xiaotai Huang
- School of Computer Science and Technology, Xidian University, Xi’an, China
- Department of Electronic Engineering, City University of Hong Kong, Kowloon, Hong Kong SAR, China
| | - Lu-Yan Chan
- Department of Biology, Hong Kong Baptist University, Kowloon, Hong Kong SAR, China
| | - Dongying Xie
- Department of Biology, Hong Kong Baptist University, Kowloon, Hong Kong SAR, China
| | - Runsheng Li
- Department of Biology, Hong Kong Baptist University, Kowloon, Hong Kong SAR, China
| | - Xiaoliang Ren
- Department of Biology, Hong Kong Baptist University, Kowloon, Hong Kong SAR, China
| | - Guoye Guan
- Center for Quantitative Biology, Peking University, Beijing, China
| | - Yiming Ma
- Department of Biology, Hong Kong Baptist University, Kowloon, Hong Kong SAR, China
| | - Boyi Hu
- Department of Biology, Hong Kong Baptist University, Kowloon, Hong Kong SAR, China
- Department of Biology, Southern University of Science and Technology, Shenzhen, China
| | - Hong Yan
- Department of Electronic Engineering, City University of Hong Kong, Kowloon, Hong Kong SAR, China
| | - Zhongying Zhao
- Department of Biology, Hong Kong Baptist University, Kowloon, Hong Kong SAR, China
- State Key Laboratory of Environmental and Biological Analysis, Hong Kong Baptist University, Kowloon, Hong Kong SAR, China
- *Correspondence: Zhongying Zhao,
| |
Collapse
|
7
|
O'Shea JM, Goutou A, Brydon J, Sethna CR, Wood CW, Greiss S. Generation of Photocaged Nanobodies for Intracellular Applications in an Animal Using Genetic Code Expansion and Computationally Guided Protein Engineering. Chembiochem 2022; 23:e202200321. [PMID: 35731601 PMCID: PMC9542635 DOI: 10.1002/cbic.202200321] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2022] [Indexed: 11/12/2022]
Abstract
Nanobodies are becoming increasingly popular as tools for manipulating and visualising proteins in vivo. The ability to control nanobody/antigen interactions using light could provide precise spatiotemporal control over protein function. We develop a general approach to engineer photo-activatable nanobodies using photocaged amino acids that are introduced into the target binding interface by genetic code expansion. Guided by computational alanine scanning and molecular dynamics simulations, we tune nanobody/target binding affinity to eliminate binding before uncaging. Upon photo-activation using 365 nm light, binding is restored. We use this approach to generate improved photocaged variants of two anti-GFP nanobodies that function robustly when directly expressed in a complex intracellular environment together with their antigen. We apply them to control subcellular protein localisation in the nematode worm Caenorhabditis elegans. Our approach applies predictions derived from computational modelling directly in a living animal and demonstrates the importance of accounting for in vivo effects on protein-protein interactions.
Collapse
Affiliation(s)
- Jack M. O'Shea
- Centre for Discovery Brain SciencesUniversity of Edinburgh, Hugh Robson Building George SquareEdinburghEH8 9XDUK
| | - Angeliki Goutou
- Centre for Discovery Brain SciencesUniversity of Edinburgh, Hugh Robson Building George SquareEdinburghEH8 9XDUK
| | - Jack Brydon
- MRC Institute of Genetics & Molecular MedicineUniversity of Edinburgh, Western General Hospital Crewe Road SouthEdinburghEH4 2XRUK
| | - Cyrus R. Sethna
- Centre for Discovery Brain SciencesUniversity of Edinburgh, Hugh Robson Building George SquareEdinburghEH8 9XDUK
| | - Christopher W. Wood
- Institute of Quantitative Biology, Biochemistry and BiotechnologyUniversity of Edinburgh, Roger Land Building King's BuildingsEdinburghEH9 3JQUK
| | - Sebastian Greiss
- Centre for Discovery Brain SciencesUniversity of Edinburgh, Hugh Robson Building George SquareEdinburghEH8 9XDUK
| |
Collapse
|
8
|
Davis L, Radman I, Goutou A, Tynan A, Baxter K, Xi Z, O'Shea JM, Chin JW, Greiss S. Precise optical control of gene expression in C. elegans using improved genetic code expansion and Cre recombinase. eLife 2021; 10:67075. [PMID: 34350826 PMCID: PMC8448529 DOI: 10.7554/elife.67075] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2021] [Accepted: 08/04/2021] [Indexed: 11/13/2022] Open
Abstract
Synthetic strategies for optically controlling gene expression may enable the precise spatiotemporal control of genes in any combination of cells that cannot be targeted with specific promoters. We develop an improved genetic code expansion system in Caenorhabditis elegans and use it to create a photoactivatable Cre recombinase. We laser-activate Cre in single neurons within a bilaterally symmetric pair to selectively switch on expression of a loxP-controlled optogenetic channel in the targeted neuron. We use the system to dissect, in freely moving animals, the individual contributions of the mechanosensory neurons PLML/PLMR to the C. elegans touch response circuit, revealing distinct and synergistic roles for these neurons. We thus demonstrate how genetic code expansion and optical targeting can be combined to break the symmetry of neuron pairs and dissect behavioural outputs of individual neurons that cannot be genetically targeted. Animal behaviour and movement emerges from the stimulation of nerve cells that are connected together like a circuit. Researchers use various tools to investigate these neural networks in model organisms such as roundworms, fruit flies and zebrafish. The trick is to activate some nerve cells, but not others, so as to isolate their specific role within the neural circuit. One way to do this is to switch genes on or off in individual cells as a way to control their neuronal activity. This can be achieved by building a photocaged version of the enzyme Cre recombinase which is designed to target specific genes. The modified Cre recombinase contains an amino acid (the building blocks of proteins) that inactivates the enzyme. When the cell is illuminated with UV light, a part of the amino acid gets removed allowing Cre recombinase to turn on its target gene. However, cells do not naturally produce these photocaged amino acids. To overcome this, researchers can use a technology called genetic code expansion which provides cells with the tools they need to build proteins containing these synthetic amino acids. Although this technique has been used in live animals, its application has been limited due to the small amount of proteins it produces. Davis et al. therefore set out to improve the efficiency of genetic code expansion so that it can be used to study single nerve cells in freely moving roundworms. In the new system, named LaserTAC, individual cells are targeted with UV light that ‘uncages’ the Cre recombinase enzyme so it can switch on a gene for a protein that controls neuronal activity. Davis et al. used this approach to stimulate a pair of neurons sensitive to touch to see how this impacted the roundworm’s behaviour. This revealed that individual neurons within this pair contribute to the touch response in different ways. However, input from both neurons is required to produce a robust reaction. These findings show that the LaserTAC system can be used to manipulate gene activity in single cells, such as neurons, using light. It allows researchers to precisely control in which cells and when a given gene is switched on or off. Also, with the improved efficiency of the genetic code expansion, this technology could be used to modify proteins other than Cre recombinase and be applied to other artificial amino acids that have been developed in recent years.
Collapse
Affiliation(s)
- Lloyd Davis
- Centre for Discovery Brain Sciences, University of Edinburgh, Edinburgh, United Kingdom
| | - Inja Radman
- Protein and Nucleic Acid Chemistry, MRC Laboratory of Molecular Biology, Cambridge, United Kingdom
| | - Angeliki Goutou
- Centre for Discovery Brain Sciences, University of Edinburgh, Edinburgh, United Kingdom
| | - Ailish Tynan
- Centre for Discovery Brain Sciences, University of Edinburgh, Edinburgh, United Kingdom
| | - Kieran Baxter
- Centre for Discovery Brain Sciences, University of Edinburgh, Edinburgh, United Kingdom
| | - Zhiyan Xi
- Centre for Discovery Brain Sciences, University of Edinburgh, Edinburgh, United Kingdom
| | - Jack M O'Shea
- Centre for Discovery Brain Sciences, University of Edinburgh, Edinburgh, United Kingdom
| | - Jason W Chin
- Medical Research Council Laboratory of Molecular Biology, Cambridge, United Kingdom
| | - Sebastian Greiss
- Centre for Discovery Brain Sciences, University of Edinburgh, Edinburgh, United Kingdom
| |
Collapse
|
9
|
Chaudhary S, Lee SA, Li Y, Patel DS, Lu H. Graphical-model framework for automated annotation of cell identities in dense cellular images. eLife 2021; 10:e60321. [PMID: 33625357 PMCID: PMC8032398 DOI: 10.7554/elife.60321] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2020] [Accepted: 02/23/2021] [Indexed: 12/11/2022] Open
Abstract
Although identifying cell names in dense image stacks is critical in analyzing functional whole-brain data enabling comparison across experiments, unbiased identification is very difficult, and relies heavily on researchers' experiences. Here, we present a probabilistic-graphical-model framework, CRF_ID, based on Conditional Random Fields, for unbiased and automated cell identification. CRF_ID focuses on maximizing intrinsic similarity between shapes. Compared to existing methods, CRF_ID achieves higher accuracy on simulated and ground-truth experimental datasets, and better robustness against challenging noise conditions common in experimental data. CRF_ID can further boost accuracy by building atlases from annotated data in highly computationally efficient manner, and by easily adding new features (e.g. from new strains). We demonstrate cell annotation in Caenorhabditis elegans images across strains, animal orientations, and tasks including gene-expression localization, multi-cellular and whole-brain functional imaging experiments. Together, these successes demonstrate that unbiased cell annotation can facilitate biological discovery, and this approach may be valuable to annotation tasks for other systems.
Collapse
Affiliation(s)
- Shivesh Chaudhary
- School of Chemical & Biomolecular Engineering, Georgia Institute of TechnologyAtlantaUnited States
| | - Sol Ah Lee
- School of Chemical & Biomolecular Engineering, Georgia Institute of TechnologyAtlantaUnited States
| | - Yueyi Li
- School of Chemical & Biomolecular Engineering, Georgia Institute of TechnologyAtlantaUnited States
| | - Dhaval S Patel
- School of Chemical & Biomolecular Engineering, Georgia Institute of TechnologyAtlantaUnited States
| | - Hang Lu
- School of Chemical & Biomolecular Engineering, Georgia Institute of TechnologyAtlantaUnited States
- Petit Institute for Bioengineering and Bioscience, Georgia Institute of TechnologyAtlantaUnited States
| |
Collapse
|
10
|
Koterniak B, Pilaka PP, Gracida X, Schneider LM, Pritišanac I, Zhang Y, Calarco JA. Global regulatory features of alternative splicing across tissues and within the nervous system of C. elegans. Genome Res 2020; 30:1766-1780. [PMID: 33127752 PMCID: PMC7706725 DOI: 10.1101/gr.267328.120] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2020] [Accepted: 10/28/2020] [Indexed: 12/27/2022]
Abstract
Alternative splicing plays a major role in shaping tissue-specific transcriptomes. Among the broad tissue types present in metazoans, the central nervous system contains some of the highest levels of alternative splicing. Although many documented examples of splicing differences between broad tissue types exist, there remains much to be understood about the splicing factors and the cis sequence elements controlling tissue and neuron subtype-specific splicing patterns. By using translating ribosome affinity purification coupled with deep-sequencing (TRAP-seq) in Caenorhabditis elegans, we have obtained high coverage profiles of ribosome-associated mRNA for three broad tissue classes (nervous system, muscle, and intestine) and two neuronal subtypes (dopaminergic and serotonergic neurons). We have identified hundreds of splice junctions that exhibit distinct splicing patterns between tissue types or within the nervous system. Alternative splicing events differentially regulated between tissues are more often frame-preserving, are more highly conserved across Caenorhabditis species, and are enriched in specific cis regulatory motifs, when compared with other types of exons. By using this information, we have identified a likely mechanism of splicing repression by the RNA-binding protein UNC-75/CELF via interactions with cis elements that overlap a 5′ splice site. Alternatively spliced exons also overlap more frequently with intrinsically disordered peptide regions than constitutive exons. Moreover, regulated exons are often shorter than constitutive exons but are flanked by longer intron sequences. Among these tissue-regulated exons are several highly conserved microexons <27 nt in length. Collectively, our results indicate a rich layer of tissue-specific gene regulation at the level of alternative splicing in C. elegans that parallels the evolutionary forces and constraints observed across metazoa.
Collapse
Affiliation(s)
- Bina Koterniak
- Department of Cell and Systems Biology, University of Toronto, Toronto, Ontario M5S 3G5, Canada
| | - Pallavi P Pilaka
- Department of Cell and Systems Biology, University of Toronto, Toronto, Ontario M5S 3G5, Canada
| | - Xicotencatl Gracida
- Department of Organismal and Evolutionary Biology, Harvard University, Cambridge, Massachusetts 02138, USA
| | - Lisa-Marie Schneider
- Department of Cell and Systems Biology, University of Toronto, Toronto, Ontario M5S 3G5, Canada.,Department of Chemistry, University of Bayreuth, 95447 Bayreuth, Germany
| | - Iva Pritišanac
- Department of Cell and Systems Biology, University of Toronto, Toronto, Ontario M5S 3G5, Canada.,Program in Molecular Medicine, The Hospital for Sick Children, Toronto, Ontario M5G 0A4, Canada
| | - Yun Zhang
- Department of Organismal and Evolutionary Biology, Harvard University, Cambridge, Massachusetts 02138, USA
| | - John A Calarco
- Department of Cell and Systems Biology, University of Toronto, Toronto, Ontario M5S 3G5, Canada
| |
Collapse
|
11
|
Thomas BJ, Wight IE, Chou WYY, Moreno M, Dawson Z, Homayouni A, Huang H, Kim H, Jia H, Buland JR, Wambach JA, Cole FS, Pak SC, Silverman GA, Luke CJ. CemOrange2 fusions facilitate multifluorophore subcellular imaging in C. elegans. PLoS One 2019; 14:e0214257. [PMID: 30913273 PMCID: PMC6435234 DOI: 10.1371/journal.pone.0214257] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2019] [Accepted: 03/08/2019] [Indexed: 11/18/2022] Open
Abstract
Due to its ease of genetic manipulation and transparency, Caenorhabditis elegans (C. elegans) has become a preferred model system to study gene function by microscopy. The use of Aequorea victoria green fluorescent protein (GFP) fused to proteins or targeting sequences of interest, further expanded upon the utility of C. elegans by labeling subcellular structures, which enables following their disposition during development or in the presence of genetic mutations. Fluorescent proteins with excitation and emission spectra different from that of GFP accelerated the use of multifluorophore imaging in real time. We have expanded the repertoire of fluorescent proteins for use in C. elegans by developing a codon-optimized version of Orange2 (CemOrange2). Proteins or targeting motifs fused to CemOrange2 were distinguishable from the more common fluorophores used in the nematode; such as GFP, YFP, and mKate2. We generated a panel of CemOrange2 fusion constructs, and confirmed they were targeted to their correct subcellular addresses by colocalization with independent markers. To demonstrate the potential usefulness of this new panel of fluorescent protein markers, we showed that CemOrange2 fusion proteins could be used to: 1) monitor biological pathways, 2) multiplex with other fluorescent proteins to determine colocalization and 3) gain phenotypic knowledge of a human ABCA3 orthologue, ABT-4, trafficking variant in the C. elegans model organism.
Collapse
Affiliation(s)
- Brian J. Thomas
- Department of Pediatrics, Washington University School of Medicine and St. Louis Children’s Hospital, St. Louis, MO, United States of America
| | - Ira E. Wight
- Department of Pediatrics, Washington University School of Medicine and St. Louis Children’s Hospital, St. Louis, MO, United States of America
| | - Wendy Y. Y. Chou
- Department of Pediatrics, Washington University School of Medicine and St. Louis Children’s Hospital, St. Louis, MO, United States of America
| | - Marco Moreno
- Department of Pediatrics, Washington University School of Medicine and St. Louis Children’s Hospital, St. Louis, MO, United States of America
| | - Zachary Dawson
- Department of Pediatrics, Washington University School of Medicine and St. Louis Children’s Hospital, St. Louis, MO, United States of America
| | - Arielle Homayouni
- Division of Biology and Biomedical Sciences, Washington University in St. Louis, St. Louis, MO, United States of America
| | - Huiyan Huang
- Department of Pediatrics, Washington University School of Medicine and St. Louis Children’s Hospital, St. Louis, MO, United States of America
| | - Hyori Kim
- Department of Pediatrics, Washington University School of Medicine and St. Louis Children’s Hospital, St. Louis, MO, United States of America
| | - Hanna Jia
- Department of Pediatrics, Washington University School of Medicine and St. Louis Children’s Hospital, St. Louis, MO, United States of America
| | - Justin R. Buland
- Department of Pediatrics, Washington University School of Medicine and St. Louis Children’s Hospital, St. Louis, MO, United States of America
| | - Jennifer A. Wambach
- Department of Pediatrics, Washington University School of Medicine and St. Louis Children’s Hospital, St. Louis, MO, United States of America
| | - F. Sessions Cole
- Department of Pediatrics, Washington University School of Medicine and St. Louis Children’s Hospital, St. Louis, MO, United States of America
- Department of Cell Biology and Physiology, Washington University School of Medicine, St. Louis, MO, United States of America
| | - Stephen C. Pak
- Department of Pediatrics, Washington University School of Medicine and St. Louis Children’s Hospital, St. Louis, MO, United States of America
| | - Gary A. Silverman
- Department of Pediatrics, Washington University School of Medicine and St. Louis Children’s Hospital, St. Louis, MO, United States of America
- Department of Cell Biology and Physiology, Washington University School of Medicine, St. Louis, MO, United States of America
- Department of Genetics, Washington University School of Medicine, St. Louis, MO, United States of America
| | - Cliff J. Luke
- Department of Pediatrics, Washington University School of Medicine and St. Louis Children’s Hospital, St. Louis, MO, United States of America
| |
Collapse
|
12
|
Abstract
Site-specific incorporation of unnatural amino acids (UAAs) has greatly expanded the toolkit available to study biological phenomena in single cells. However, to address questions involving complex cellular interactions such as development, ageing, and the functions of the nervous system it is often necessary to use multicellular model organisms. The nematode Caenorhabditis elegans was the first organism to have its genetic code expanded. Due to its small size, ease of cultivation, and excellent UAA incorporation efficiency, C. elegans makes an ideal model organism to apply UAAs as tools to investigate the functioning of multicellular systems.Here, we describe methods to generate transgenic C. elegans capable of UAA incorporation, as well as how to deliver unnatural amino acids and test incorporation. Furthermore, we describe methods to uncage photosensitive unnatural amino acid derivatives.
Collapse
Affiliation(s)
- Lloyd Davis
- Centre for Integrative Physiology, University of Edinburgh, Edinburgh, UK
| | - Sebastian Greiss
- Centre for Integrative Physiology, University of Edinburgh, Edinburgh, UK.
| |
Collapse
|
13
|
de la Cova C, Townley R, Regot S, Greenwald I. A Real-Time Biosensor for ERK Activity Reveals Signaling Dynamics during C. elegans Cell Fate Specification. Dev Cell 2017; 42:542-553.e4. [PMID: 28826819 PMCID: PMC5595649 DOI: 10.1016/j.devcel.2017.07.014] [Citation(s) in RCA: 92] [Impact Index Per Article: 13.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2017] [Revised: 06/19/2017] [Accepted: 07/20/2017] [Indexed: 01/06/2023]
Abstract
Kinase translocation reporters (KTRs) are genetically encoded fluorescent activity sensors that convert kinase activity into a nucleocytoplasmic shuttling equilibrium for visualizing single-cell signaling dynamics. Here, we adapt the first-generation KTR for extracellular signal-regulated kinase (ERK) to allow easy implementation in vivo. This sensor, "ERK-nKTR," allows quantitative and qualitative assessment of ERK activity by analysis of individual nuclei and faithfully reports ERK activity during development and neural function in diverse cell contexts in Caenorhabditis elegans. Analysis of ERK activity over time in the vulval precursor cells, a well-characterized paradigm of epidermal growth factor receptor (EGFR)-Ras-ERK signaling, has identified dynamic features not evident from analysis of developmental endpoints alone, including pulsatile frequency-modulated signaling associated with proximity to the EGF source. The toolkit described here will facilitate studies of ERK signaling in other C. elegans contexts, and the design features will enable implementation of this technology in other multicellular organisms.
Collapse
Affiliation(s)
- Claire de la Cova
- Department of Biological Sciences, Columbia University, New York, NY, USA; Department of Biochemistry & Molecular Biophysics, Columbia University Medical Center, New York, NY, USA
| | - Robert Townley
- Department of Biological Sciences, Columbia University, New York, NY, USA
| | - Sergi Regot
- Department of Molecular Biology & Genetics, The Johns Hopkins University School of Medicine, Baltimore, MD, USA.
| | - Iva Greenwald
- Department of Biological Sciences, Columbia University, New York, NY, USA; Department of Biochemistry & Molecular Biophysics, Columbia University Medical Center, New York, NY, USA.
| |
Collapse
|
14
|
The Bright Fluorescent Protein mNeonGreen Facilitates Protein Expression Analysis In Vivo. G3-GENES GENOMES GENETICS 2017; 7:607-615. [PMID: 28108553 PMCID: PMC5295605 DOI: 10.1534/g3.116.038133] [Citation(s) in RCA: 44] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
The Green Fluorescent Protein (GFP) has been tremendously useful in investigating cell architecture, protein localization, and protein function. Recent developments in transgenesis and genome editing methods now enable working with fewer transgene copies and, consequently, with physiological expression levels. However, lower signal intensity might become a limiting factor. The recently developed mNeonGreen protein is a brighter alternative to GFP in vitro. The goal of the present study was to determine how mNeonGreen performs in vivo in Caenorhabditis elegans—a model used extensively for fluorescence imaging in intact animals. We started with a side-by-side comparison between cytoplasmic forms of mNeonGreen and GFP expressed in the intestine, and in different neurons, of adult animals. While both proteins had similar photostability, mNeonGreen was systematically 3–5 times brighter than GFP. mNeonGreen was also used successfully to trace endogenous proteins, and label specific subcellular compartments such as the nucleus or the plasma membrane. To further demonstrate the utility of mNeonGreen, we tested transcriptional reporters for nine genes with unknown expression patterns. While mNeonGreen and GFP reporters gave overall similar expression patterns, low expression tissues were detected only with mNeonGreen. As a whole, our work establishes mNeonGreen as a brighter alternative to GFP for in vivo imaging in a multicellular organism. Furthermore, the present research illustrates the utility of mNeonGreen to tag proteins, mark subcellular regions, and describe new expression patterns, particularly in tissues with low expression.
Collapse
|
15
|
Cohen-Fix O, Askjaer P. Cell Biology of the Caenorhabditis elegans Nucleus. Genetics 2017; 205:25-59. [PMID: 28049702 PMCID: PMC5216270 DOI: 10.1534/genetics.116.197160] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2016] [Accepted: 11/09/2016] [Indexed: 12/25/2022] Open
Abstract
Studies on the Caenorhabditis elegans nucleus have provided fascinating insight to the organization and activities of eukaryotic cells. Being the organelle that holds the genetic blueprint of the cell, the nucleus is critical for basically every aspect of cell biology. The stereotypical development of C. elegans from a one cell-stage embryo to a fertile hermaphrodite with 959 somatic nuclei has allowed the identification of mutants with specific alterations in gene expression programs, nuclear morphology, or nuclear positioning. Moreover, the early C. elegans embryo is an excellent model to dissect the mitotic processes of nuclear disassembly and reformation with high spatiotemporal resolution. We review here several features of the C. elegans nucleus, including its composition, structure, and dynamics. We also discuss the spatial organization of chromatin and regulation of gene expression and how this depends on tight control of nucleocytoplasmic transport. Finally, the extensive connections of the nucleus with the cytoskeleton and their implications during development are described. Most processes of the C. elegans nucleus are evolutionarily conserved, highlighting the relevance of this powerful and versatile model organism to human biology.
Collapse
Affiliation(s)
- Orna Cohen-Fix
- Laboratory of Molecular and Cellular Biology, National Institute of Diabetes, Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892
| | - Peter Askjaer
- Andalusian Center for Developmental Biology, Consejo Superior de Investigaciones Científicas/Junta de Andalucia/Universidad Pablo de Olavide, 41013 Seville, Spain
| |
Collapse
|
16
|
Quintero-Cadena P, Sternberg PW. Enhancer Sharing Promotes Neighborhoods of Transcriptional Regulation Across Eukaryotes. G3 (BETHESDA, MD.) 2016; 6:4167-4174. [PMID: 27799341 PMCID: PMC5144984 DOI: 10.1534/g3.116.036228] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/28/2016] [Accepted: 10/15/2016] [Indexed: 01/08/2023]
Abstract
Enhancers physically interact with transcriptional promoters, looping over distances that can span multiple regulatory elements. Given that enhancer-promoter (EP) interactions generally occur via common protein complexes, it is unclear whether EP pairing is predominantly deterministic or proximity guided. Here, we present cross-organismic evidence suggesting that most EP pairs are compatible, largely determined by physical proximity rather than specific interactions. By reanalyzing transcriptome datasets, we find that the transcription of gene neighbors is correlated over distances that scale with genome size. We experimentally show that nonspecific EP interactions can explain such correlation, and that EP distance acts as a scaling factor for the transcriptional influence of an enhancer. We propose that enhancer sharing is commonplace among eukaryotes, and that EP distance is an important layer of information in gene regulation.
Collapse
Affiliation(s)
- Porfirio Quintero-Cadena
- Division of Biology and Biological Engineering, California Institute of Technology, Howard Hughes Medical Institute, Pasadena, California 91125
| | - Paul W Sternberg
- Division of Biology and Biological Engineering, California Institute of Technology, Howard Hughes Medical Institute, Pasadena, California 91125
| |
Collapse
|
17
|
Budirahardja Y, Tan PY, Doan T, Weisdepp P, Zaidel-Bar R. The AP-2 Transcription Factor APTF-2 Is Required for Neuroblast and Epidermal Morphogenesis in Caenorhabditis elegans Embryogenesis. PLoS Genet 2016; 12:e1006048. [PMID: 27176626 PMCID: PMC4866721 DOI: 10.1371/journal.pgen.1006048] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2016] [Accepted: 04/21/2016] [Indexed: 11/19/2022] Open
Abstract
The evolutionarily conserved family of AP-2 transcription factors (TF) regulates proliferation, differentiation, and apoptosis. Mutations in human AP-2 TF have been linked with bronchio-occular-facial syndrome and Char Syndrome, congenital birth defects characterized by craniofacial deformities and patent ductus arteriosus, respectively. How mutations in AP-2 TF cause the disease phenotypes is not well understood. Here, we characterize the aptf-2(qm27) allele in Caenorhabditis elegans, which carries a point mutation in the conserved DNA binding region of AP-2 TF. We show that compromised APTF-2 activity leads to defects in dorsal intercalation, aberrant ventral enclosure and elongation defects, ultimately culminating in the formation of morphologically deformed larvae or complete arrest during epidermal morphogenesis. Using cell lineaging, we demonstrate that APTF-2 regulates the timing of cell division, primarily in ABarp, D and C cell lineages to control the number of neuroblasts, muscle and epidermal cells. Live imaging revealed nuclear enrichment of APTF-2 in lineages affected by the qm27 mutation preceding the relevant morphogenetic events. Finally, we found that another AP-2 TF, APTF-4, is also essential for epidermal morphogenesis, in a similar yet independent manner. Thus, our study provides novel insight on the cellular-level functions of an AP-2 transcription factor in development. Mutations in the evolutionarily conserved family of AP-2 transcription factors are associated with multiple birth defects in Char syndrome and Brancio-oculo-facial syndrome. These DNA-binding proteins are known to regulate the proliferation, differentiation and death of specific cells during embryonic development but how point mutations in the AP-2 DNA-binding domain lead to these diseases during development is currently unknown. We have identified a mutation in one of the AP-2 orthologs of the nematode Caenorhabditis elegans, APTF-2, which falls in the same mutation hotspot as in human Char syndrome and Brancio-oculo-facial syndrome patients. Compromised APTF-2 activity in C. elegans results in embryonic lethality and embryos that survive to hatching displays body morphological defects, reminiscent of the aforementioned human diseases. Using time-lapse microscopy, we found that misregulation of cell division in the skin, muscle and neuronal cell lineages is the primary cause of developmental arrest. Our study provides insight into the regulation of cell division timing by AP-2 transcription factors and provides a model to study human diseases associated with AP-2 mutations.
Collapse
Affiliation(s)
| | - Pei Yi Tan
- Mechanobiology Institute, National University of Singapore, Singapore
| | - Thang Doan
- Mechanobiology Institute, National University of Singapore, Singapore
| | - Peter Weisdepp
- Department of Genome Sciences, University of Washington, Seattle, Washington, United States of America
| | - Ronen Zaidel-Bar
- Mechanobiology Institute, National University of Singapore, Singapore
- Department of Biomedical Engineering, National University of Singapore, Singapore
- * E-mail:
| |
Collapse
|
18
|
Schild LC, Zbinden L, Bell HW, Yu YV, Sengupta P, Goodman MB, Glauser DA. The balance between cytoplasmic and nuclear CaM kinase-1 signaling controls the operating range of noxious heat avoidance. Neuron 2014; 84:983-96. [PMID: 25467982 DOI: 10.1016/j.neuron.2014.10.039] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/15/2014] [Indexed: 12/12/2022]
Abstract
Through encounters with predators, competitors, and noxious stimuli, animals have evolved defensive responses that minimize injury and are essential for survival. Physiological adaptation modulates the stimulus intensities that trigger such nocifensive behaviors, but the molecular networks that define their operating range are largely unknown. Here, we identify a gain-of-function allele of the cmk-1 CaMKI gene in C. elegans and show that loss of the regulatory domain of the CaMKI enzyme produces thermal analgesia and shifts the operating range for nocifensive heat avoidance to higher temperatures. Such analgesia depends on nuclear CMK-1 signaling, while cytoplasmic CMK-1 signaling lowers the threshold for thermal avoidance. CMK-1 acts downstream of heat detection in thermal receptor neurons and controls neuropeptide release. Our results establish CaMKI as a key regulator of the operating range for nocifensive behaviors and suggest strategies for producing thermal analgesia through the regulation of CaMKI-dependent signaling.
Collapse
Affiliation(s)
- Lisa C Schild
- Department of Biology, University of Fribourg, 1700 Fribourg, Switzerland
| | - Laurie Zbinden
- Department of Biology, University of Fribourg, 1700 Fribourg, Switzerland
| | - Harold W Bell
- Department of Biology and National Center for Behavioral Genomics, Brandeis University, Waltham, MA 02454, USA
| | - Yanxun V Yu
- Department of Biology and National Center for Behavioral Genomics, Brandeis University, Waltham, MA 02454, USA
| | - Piali Sengupta
- Department of Biology and National Center for Behavioral Genomics, Brandeis University, Waltham, MA 02454, USA
| | - Miriam B Goodman
- Department of Molecular and Cellular Physiology, Stanford School of Medicine, Stanford, CA 94305, USA.
| | | |
Collapse
|
19
|
Schrödel T, Prevedel R, Aumayr K, Zimmer M, Vaziri A. Brain-wide 3D imaging of neuronal activity in Caenorhabditis elegans with sculpted light. Nat Methods 2013; 10:1013-20. [PMID: 24013820 DOI: 10.1038/nmeth.2637] [Citation(s) in RCA: 190] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2013] [Accepted: 08/07/2013] [Indexed: 12/18/2022]
|
20
|
Identification of a non-canonical nuclear localization signal (NLS) in BRCA1 that could mediate nuclear localization of splice variants lacking the classical NLS. Cell Mol Biol Lett 2013; 18:284-96. [PMID: 23666596 PMCID: PMC6275570 DOI: 10.2478/s11658-013-0088-x] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2012] [Accepted: 04/18/2013] [Indexed: 11/21/2022] Open
Abstract
The breast cancer type 1 susceptibility gene (BRCA1) is a tumor suppressor gene, mutations or loss of which lead to genomic instability and breast cancer. BRCA1 protein is part of a large multi-protein complex involved in a variety of DNA repair and transcription regulatory functions. At least four splice variants have been described and these differ in their function and tissue and spatio-temporal expression patterns. Structural analysis has revealed the presence of two nuclear localization signals (NLS) located in exon 11 of BRCA1. Interestingly, a splice variant of the protein that lacks both of the known NLS still manages to gain entry to the nucleus. While there is experimental proof for the translocation of these proteins by binding to other established nuclear proteins, we examined the possibility of a hitherto unidentified NLS in this particular variant. In this paper, we present evidence for the existence of a previously unreported non-canonical NLS contained within the first 39 amino acids of exon 11. A fusion protein with this 39mer and a reporter green fluorescent protein translocated into the nucleus when it was expressed in breast epithelial cells. We demonstrate the presence of a hitherto unreported noncanonical NLS in exon 11a of BRCA1. This NLS might aid proteins that were encoded by splice variants and lack the canonical NLS to localize to the nucleus.
Collapse
|
21
|
Lyssenko NN, Miteva Y, Gilroy S, Hanna-Rose W, Schlegel RA. An unexpectedly high degree of specialization and a widespread involvement in sterol metabolism among the C. elegans putative aminophospholipid translocases. BMC DEVELOPMENTAL BIOLOGY 2008; 8:96. [PMID: 18831765 PMCID: PMC2572054 DOI: 10.1186/1471-213x-8-96] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/30/2008] [Accepted: 10/02/2008] [Indexed: 12/17/2022]
Abstract
Background P-type ATPases in subfamily IV are exclusively eukaryotic transmembrane proteins that have been proposed to directly translocate the aminophospholipids phosphatidylserine and phosphatidylethanolamine from the exofacial to the cytofacial monolayer of the plasma membrane. Eukaryotic genomes contain many genes encoding members of this subfamily. At present it is unclear why there are so many genes of this kind per organism or what individual roles these genes perform in organism development. Results We have systematically investigated expression and developmental function of the six, tat-1 through 6, subfamily IV P-type ATPase genes encoded in the Caenorhabditis elegans genome. tat-5 is the only ubiquitously-expressed essential gene in the group. tat-6 is a poorly-transcribed recent duplicate of tat-5. tat-2 through 4 exhibit tissue-specific developmentally-regulated expression patterns. Strong expression of both tat-2 and tat-4 occurs in the intestine and certain other cells of the alimentary system. The two are also expressed in the uterus, during spermatogenesis and in the fully-formed spermatheca. tat-2 alone is expressed in the pharyngeal gland cells, the excretory system and a few cells of the developing vulva. The expression pattern of tat-3 is almost completely different from those of tat-2 and tat-4. tat-3 expression is detectable in the steroidogenic tissues: the hypodermis and the XXX cells, as well as in most cells of the pharynx (except gland), various tissues of the reproductive system (except uterus and spermatheca) and seam cells. Deletion of tat-1 through 4 individually interferes little or not at all with the regular progression of organism growth and development under normal conditions. However, tat-2 through 4 become essential for reproductive growth during sterol starvation. Conclusion tat-5 likely encodes a housekeeping protein that performs the proposed aminophospholipid translocase function routinely. Although individually dispensable, tat-1 through 4 seem to be at most only partly redundant. Expression patterns and the sterol deprivation hypersensitivity deletion phenotype of tat-2 through 4 suggest that these genes carry out subtle metabolic functions, such as fine-tuning sterol metabolism in digestive or steroidogenic tissues. These findings uncover an unexpectedly high degree of specialization and a widespread involvement in sterol metabolism among the genes encoding the putative aminophospholipid translocases.
Collapse
Affiliation(s)
- Nicholas N Lyssenko
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, Pennsylvania 16802, USA.
| | | | | | | | | |
Collapse
|