1
|
Haley JA, Chalasani SH. C. elegans foraging as a model for understanding the neuronal basis of decision-making. Cell Mol Life Sci 2024; 81:252. [PMID: 38849591 DOI: 10.1007/s00018-024-05223-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2023] [Revised: 03/27/2024] [Accepted: 03/30/2024] [Indexed: 06/09/2024]
Abstract
Animals have evolved to seek, select, and exploit food sources in their environment. Collectively termed foraging, these ubiquitous behaviors are necessary for animal survival. As a foundation for understanding foraging, behavioral ecologists established early theoretical and mathematical frameworks which have been subsequently refined and supported by field and laboratory studies of foraging animals. These simple models sought to explain how animals decide which strategies to employ when locating food, what food items to consume, and when to explore the environment for new food sources. These foraging decisions involve integration of prior experience with multimodal sensory information about the animal's current environment and internal state. We suggest that the nematode Caenorhabditis elegans is well-suited for a high-resolution analysis of complex goal-oriented behaviors such as foraging. We focus our discussion on behavioral studies highlighting C. elegans foraging on bacteria and summarize what is known about the underlying neuronal and molecular pathways. Broadly, we suggest that this simple model system can provide a mechanistic understanding of decision-making and present additional avenues for advancing our understanding of complex behavioral processes.
Collapse
Affiliation(s)
- Jessica A Haley
- Neurosciences Graduate Program, University of California San Diego, La Jolla, CA, 92093, USA
- Molecular Neurobiology Laboratory, Salk Institute for Biological Studies, La Jolla, CA, 92037, USA
| | - Sreekanth H Chalasani
- Molecular Neurobiology Laboratory, Salk Institute for Biological Studies, La Jolla, CA, 92037, USA.
| |
Collapse
|
2
|
Lin C, Shan Y, Wang Z, Peng H, Li R, Wang P, He J, Shen W, Wu Z, Guo M. Molecular and circuit mechanisms underlying avoidance of rapid cooling stimuli in C. elegans. Nat Commun 2024; 15:297. [PMID: 38182628 PMCID: PMC10770330 DOI: 10.1038/s41467-023-44638-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2023] [Accepted: 12/21/2023] [Indexed: 01/07/2024] Open
Abstract
The mechanisms by which animals respond to rapid changes in temperature are largely unknown. Here, we found that polymodal ASH sensory neurons mediate rapid cooling-evoked avoidance behavior within the physiological temperature range in C. elegans. ASH employs multiple parallel circuits that consist of stimulatory circuits (AIZ, RIA, AVA) and disinhibitory circuits (AIB, RIM) to respond to rapid cooling. In the stimulatory circuit, AIZ, which is activated by ASH, releases glutamate to act on both GLR-3 and GLR-6 receptors in RIA neurons to promote reversal, and ASH also directly or indirectly stimulates AVA to promote reversal. In the disinhibitory circuit, AIB is stimulated by ASH through the GLR-1 receptor, releasing glutamate to act on AVR-14 to suppress RIM activity. RIM, an inter/motor neuron, inhibits rapid cooling-evoked reversal, and the loop activities thus equally stimulate reversal. Our findings elucidate the molecular and circuit mechanisms underlying the acute temperature stimuli-evoked avoidance behavior.
Collapse
Affiliation(s)
- Chenxi Lin
- College of Life Science and Technology, Huazhong Agricultural University, Wuhan, Hubei, 430070, China
- College of Biomedicine and Health, Huazhong Agricultural University, Wuhan, 430070, China
| | - Yuxin Shan
- College of Life Science and Technology, Huazhong Agricultural University, Wuhan, Hubei, 430070, China
- College of Biomedicine and Health, Huazhong Agricultural University, Wuhan, 430070, China
| | - Zhongyi Wang
- College of Life Science and Technology, Huazhong Agricultural University, Wuhan, Hubei, 430070, China
- College of Biomedicine and Health, Huazhong Agricultural University, Wuhan, 430070, China
| | - Hui Peng
- College of Life Science and Technology, Huazhong Agricultural University, Wuhan, Hubei, 430070, China
| | - Rong Li
- Key Laboratory of Molecular Biophysics of Ministry of Education, Institute of Biophysics and Biochemistry, and Department of Biophysics and Molecular Physiology, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, 430074, China
| | - Pingzhou Wang
- Key Laboratory of Molecular Biophysics of Ministry of Education, Institute of Biophysics and Biochemistry, and Department of Biophysics and Molecular Physiology, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, 430074, China
| | - Junyan He
- College of Life Science and Technology, Huazhong Agricultural University, Wuhan, Hubei, 430070, China
| | - Weiwei Shen
- College of Life Science and Technology, Huazhong Agricultural University, Wuhan, Hubei, 430070, China
| | - Zhengxing Wu
- Key Laboratory of Molecular Biophysics of Ministry of Education, Institute of Biophysics and Biochemistry, and Department of Biophysics and Molecular Physiology, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, 430074, China
| | - Min Guo
- College of Life Science and Technology, Huazhong Agricultural University, Wuhan, Hubei, 430070, China.
- College of Biomedicine and Health, Huazhong Agricultural University, Wuhan, 430070, China.
| |
Collapse
|
3
|
Nava S, Palma W, Wan X, Oh JY, Gharib S, Wang H, Revanna JS, Tan M, Zhang M, Liu J, Chen CH, Lee JS, Perry B, Sternberg PW. A cGAL-UAS bipartite expression toolkit for Caenorhabditis elegans sensory neurons. Proc Natl Acad Sci U S A 2023; 120:e2221680120. [PMID: 38096407 PMCID: PMC10743456 DOI: 10.1073/pnas.2221680120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2022] [Accepted: 10/05/2023] [Indexed: 12/18/2023] Open
Abstract
Animals integrate sensory information from the environment and display various behaviors in response to external stimuli. In Caenorhabditis elegans hermaphrodites, 33 types of sensory neurons are responsible for chemosensation, olfaction, and mechanosensation. However, the functional roles of all sensory neurons have not been systematically studied due to the lack of facile genetic accessibility. A bipartite cGAL-UAS system has been previously developed to study tissue- or cell-specific functions in C. elegans. Here, we report a toolkit of new cGAL drivers that can facilitate the analysis of a vast majority of the 60 sensory neurons in C. elegans hermaphrodites. We generated 37 sensory neuronal cGAL drivers that drive cGAL expression by cell-specific regulatory sequences or intersection of two distinct regulatory regions with overlapping expression (split cGAL). Most cGAL-drivers exhibit expression in single types of cells. We also constructed 28 UAS effectors that allow expression of proteins to perturb or interrogate sensory neurons of choice. This cGAL-UAS sensory neuron toolkit provides a genetic platform to systematically study the functions of C. elegans sensory neurons.
Collapse
Affiliation(s)
- Stephanie Nava
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA91125
| | - Wilber Palma
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA91125
| | - Xuan Wan
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA91125
| | - Jun Young Oh
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA91125
| | - Shahla Gharib
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA91125
| | - Han Wang
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA91125
| | - Jasmin S. Revanna
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA91125
| | - Minyi Tan
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA91125
| | - Mark Zhang
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA91125
| | - Jonathan Liu
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA91125
| | - Chun-Hao Chen
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA91125
| | - James S. Lee
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA91125
| | - Barbara Perry
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA91125
| | - Paul W. Sternberg
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA91125
| |
Collapse
|
4
|
Fang J, Wang J, Wang Y, Liu X, Chen B, Zou W. Ribo-On and Ribo-Off tools using a self-cleaving ribozyme allow manipulation of endogenous gene expression in C. elegans. Commun Biol 2023; 6:816. [PMID: 37542105 PMCID: PMC10403566 DOI: 10.1038/s42003-023-05184-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2022] [Accepted: 07/26/2023] [Indexed: 08/06/2023] Open
Abstract
Investigating gene function relies on the efficient manipulation of endogenous gene expression. Currently, a limited number of tools are available to robustly manipulate endogenous gene expression between "on" and "off" states. In this study, we insert a 63 bp coding sequence of T3H38 ribozyme into the 3' untranslated region (UTR) of C. elegans endogenous genes using the CRISPR/Cas9 technology, which reduces the endogenous gene expression to a nearly undetectable level and generated loss-of-function phenotypes similar to that of the genetic null animals. To achieve conditional knockout, a cassette of loxP-flanked transcriptional termination signal and ribozyme is inserted into the 3' UTR of endogenous genes, which eliminates gene expression spatially or temporally via the controllable expression of the Cre recombinase. Conditional endogenous gene turn-on can be achieved by either injecting morpholino, which blocks the ribozyme self-cleavage activity or using the Cre recombinase to remove the loxP-flanked ribozyme. Together, our results demonstrate that these ribozyme-based tools can efficiently manipulate endogenous gene expression both in space and time and expand the toolkit for studying the functions of endogenous genes.
Collapse
Affiliation(s)
- Jie Fang
- The Fourth Affiliated Hospital, Zhejiang University School of Medicine, 322000, Yiwu, China
- Institute of Translational Medicine, Zhejiang University, 310058, Hangzhou, China
- Department of Cell Biology and Bone Marrow Transplantation Center of the First Affiliated Hospital, Zhejiang University School of Medicine, 310058, Hangzhou, China
| | - Jie Wang
- The Fourth Affiliated Hospital, Zhejiang University School of Medicine, 322000, Yiwu, China
- Institute of Translational Medicine, Zhejiang University, 310058, Hangzhou, China
| | - Yuzhi Wang
- The Fourth Affiliated Hospital, Zhejiang University School of Medicine, 322000, Yiwu, China
- Institute of Translational Medicine, Zhejiang University, 310058, Hangzhou, China
| | - Xiaofan Liu
- The Fourth Affiliated Hospital, Zhejiang University School of Medicine, 322000, Yiwu, China
- Institute of Translational Medicine, Zhejiang University, 310058, Hangzhou, China
| | - Baohui Chen
- Department of Cell Biology and Bone Marrow Transplantation Center of the First Affiliated Hospital, Zhejiang University School of Medicine, 310058, Hangzhou, China.
- Zhejiang Laboratory for Systems & Precision Medicine, Zhejiang University Medical Center, Hangzhou, China.
- Institute of Hematology, Zhejiang University & Zhejiang Engineering Laboratory for Stem Cell and Immunotherapy, Hangzhou, China.
- Zhejiang Provincial Key Laboratory of Genetic & Developmental Disorders, Hangzhou, China.
| | - Wei Zou
- The Fourth Affiliated Hospital, Zhejiang University School of Medicine, 322000, Yiwu, China.
- Institute of Translational Medicine, Zhejiang University, 310058, Hangzhou, China.
| |
Collapse
|
5
|
Kukhtar D, Fussenegger M. Synthetic biology in multicellular organisms: Opportunities in nematodes. Biotechnol Bioeng 2023. [PMID: 37448225 DOI: 10.1002/bit.28497] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2023] [Revised: 04/27/2023] [Accepted: 07/05/2023] [Indexed: 07/15/2023]
Abstract
Synthetic biology has mainly focused on introducing new or altered functionality in single cell systems: primarily bacteria, yeast, or mammalian cells. Here, we describe the extension of synthetic biology to nematodes, in particular the well-studied model organism Caenorhabditis elegans, as a convenient platform for developing applications in a multicellular setting. We review transgenesis techniques for nematodes, as well as the application of synthetic biology principles to construct nematode gene switches and genetic devices to control motility. Finally, we discuss potential applications of engineered nematodes.
Collapse
Affiliation(s)
- Dmytro Kukhtar
- Department of Biosystems Science and Engineering, ETH Zürich, Basel, Switzerland
| | - Martin Fussenegger
- Department of Biosystems Science and Engineering, ETH Zürich, Basel, Switzerland
- Faculty of Life Science, University of Basel, Basel, Switzerland
| |
Collapse
|
6
|
Xiao Y, Yee C, Zhao CZ, Martinez MAQ, Zhang W, Shen K, Matus DQ, Hammell C. An expandable FLP-ON::TIR1 system for precise spatiotemporal protein degradation in Caenorhabditis elegans. Genetics 2023; 223:iyad013. [PMID: 36722258 PMCID: PMC10319979 DOI: 10.1093/genetics/iyad013] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2022] [Accepted: 01/16/2023] [Indexed: 02/02/2023] Open
Abstract
The auxin-inducible degradation system has been widely adopted in the Caenorhabditis elegans research community for its ability to empirically control the spatiotemporal expression of target proteins. This system can efficiently degrade auxin-inducible degron (AID)-tagged proteins via the expression of a ligand-activatable AtTIR1 protein derived from A. thaliana that adapts target proteins to the endogenous C. elegans proteasome. While broad expression of AtTIR1 using strong, ubiquitous promoters can lead to rapid degradation of AID-tagged proteins, cell type-specific expression of AtTIR1 using spatially restricted promoters often results in less efficient target protein degradation. To circumvent this limitation, we have developed an FLP/FRT3-based system that functions to reanimate a dormant, high-powered promoter that can drive sufficient AtTIR1 expression in a cell type-specific manner. We benchmark the utility of this system by generating a number of tissue-specific FLP-ON::TIR1 drivers to reveal genetically separable cell type-specific phenotypes for several target proteins. We also demonstrate that the FLP-ON::TIR1 system is compatible with enhanced degron epitopes. Finally, we provide an expandable toolkit utilizing the basic FLP-ON::TIR1 system that can be adapted to drive optimized AtTIR1 expression in any tissue or cell type of interest.
Collapse
Affiliation(s)
- Yutong Xiao
- Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, NY 11794, USA
| | - Callista Yee
- Howard Hughes Medical Institute, Department of Biology, Stanford University, Stanford, CA 94305, USA
| | - Chris Z Zhao
- Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, NY 11794, USA
| | - Michael A Q Martinez
- Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, NY 11794, USA
| | - Wan Zhang
- Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, NY 11794, USA
| | - Kang Shen
- Howard Hughes Medical Institute, Department of Biology, Stanford University, Stanford, CA 94305, USA
| | - David Q Matus
- Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, NY 11794, USA
| | | |
Collapse
|
7
|
Thapliyal S, Glauser DA. Neurogenetic Analysis in Caenorhabditis elegans. Neurogenetics 2023. [DOI: 10.1007/978-3-031-07793-7_2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
|
8
|
Chen YJ, Pan CL. An olfactory-interneuron circuit that drives stress-induced avoidance behavior in C. elegans. Neurosci Res 2022; 191:91-97. [PMID: 36565857 DOI: 10.1016/j.neures.2022.12.012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2022] [Revised: 11/23/2022] [Accepted: 12/18/2022] [Indexed: 12/24/2022]
Abstract
Physiological stress represents a drastic change of internal state and can drive avoidance behavior, but the neural circuits are incompletely defined. Here, we characterize a sensory-interneuron circuit for mitochondrial stress-induced avoidance behavior in C. elegans. The olfactory sensory neurons and the AIY interneuron are essential, with the olfactory neurons acting upstream of AIY. Unlike pathogen avoidance, stress-induced avoidance does not require AIB, AIZ or RIA interneurons. Ablation or inhibition of the head motor neurons SMDD/V alters the worm's locomotion and reduces avoidance. These findings substantiate our understanding of the circuit mechanisms that underlie learned avoidance behavior triggered by mitochondrial stress.
Collapse
Affiliation(s)
- Yen-Ju Chen
- Institute of Molecular Medicine and Center for Precision Medicine, College of Medicine, National Taiwan University, Taipei 10002, Taiwan
| | - Chun-Liang Pan
- Institute of Molecular Medicine and Center for Precision Medicine, College of Medicine, National Taiwan University, Taipei 10002, Taiwan.
| |
Collapse
|
9
|
Fragoso-Luna A, Romero-Bueno R, Eibl M, Ayuso C, Muñoz-Jiménez C, Benes V, Cases I, Askjaer P. Expanded FLP toolbox for spatiotemporal protein degradation and transcriptomic profiling in Caenorhabditis elegans. Genetics 2022; 223:6793861. [PMID: 36321973 PMCID: PMC9836023 DOI: 10.1093/genetics/iyac166] [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: 10/03/2022] [Accepted: 10/24/2022] [Indexed: 11/05/2022] Open
Abstract
Control of gene expression in specific tissues and/or at certain stages of development allows the study and manipulation of gene function with high precision. Site-specific genome recombination by the flippase (FLP) and cyclization recombination (Cre) enzymes has proved particularly relevant. Joint efforts of many research groups have led to the creation of efficient FLP and Cre drivers to regulate gene expression in a variety of tissues in Caenorhabditis elegans. Here, we extend this toolkit by the addition of FLP lines that drive recombination specifically in distal tip cells, the somatic gonad, coelomocytes, and the epithelial P lineage. In some cases, recombination-mediated gene knockouts do not completely deplete protein levels due to persistence of long-lived proteins. To overcome this, we developed a spatiotemporally regulated degradation system for green fluorescent fusion proteins based on FLP-mediated recombination. Using 2 stable nuclear pore proteins, MEL-28/ELYS and NPP-2/NUP85 as examples, we report the benefit of combining tissue-specific gene knockout and protein degradation to achieve complete protein depletion. We also demonstrate that FLP-mediated recombination can be utilized to identify transcriptomes in a C. elegans tissue of interest. We have adapted RNA polymerase DamID for the FLP toolbox and by focusing on a well-characterized tissue, the hypodermis, we show that the vast majority of genes identified by RNA polymerase DamID are known to be expressed in this tissue. These tools allow combining FLP activity for simultaneous gene inactivation and transcriptomic profiling, thus enabling the inquiry of gene function in various complex biological processes.
Collapse
Affiliation(s)
| | | | | | - Cristina Ayuso
- Andalusian Centre for Developmental Biology, Consejo Superior de Investigaciones Científicas (CSIC), Universidad Pablo de Olavide, Junta de Andalucía, 41013 Sevilla, Spain
| | - Celia Muñoz-Jiménez
- Andalusian Centre for Developmental Biology, Consejo Superior de Investigaciones Científicas (CSIC), Universidad Pablo de Olavide, Junta de Andalucía, 41013 Sevilla, Spain
| | | | - Ildefonso Cases
- Andalusian Centre for Developmental Biology, Consejo Superior de Investigaciones Científicas (CSIC), Universidad Pablo de Olavide, Junta de Andalucía, 41013 Sevilla, Spain
| | - Peter Askjaer
- Corresponding author: Andalusian Centre for Developmental Biology, Gene Regulation and Morphogenesis, CSIC—Universidad Pablo de Olavide, Carretera de Utrera, km 1, 41013 Seville, Spain.
| |
Collapse
|
10
|
Sepers JJ, Verstappen NHM, Vo AA, Ragle JM, Ruijtenberg S, Ward JD, Boxem M. The mIAA7 degron improves auxin-mediated degradation in Caenorhabditiselegans. G3 (BETHESDA, MD.) 2022; 12:jkac222. [PMID: 36029236 PMCID: PMC9526053 DOI: 10.1093/g3journal/jkac222] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/01/2022] [Accepted: 08/15/2022] [Indexed: 04/08/2023]
Abstract
Auxin-inducible degradation is a powerful tool for the targeted degradation of proteins with spatiotemporal control. One limitation of the auxin-inducible degradation system is that not all proteins are degraded efficiently. Here, we demonstrate that an alternative degron sequence, termed mIAA7, improves the efficiency of degradation in Caenorhabditiselegans, as previously reported in human cells. We tested the depletion of a series of proteins with various subcellular localizations in different tissue types and found that the use of the mIAA7 degron resulted in faster depletion kinetics for 5 out of 6 proteins tested. The exception was the nuclear protein HIS-72, which was depleted with similar efficiency as with the conventional AID* degron sequence. The mIAA7 degron also increased the leaky degradation for 2 of the tested proteins. To overcome this problem, we combined the mIAA7 degron with the C. elegans AID2 system, which resulted in complete protein depletion without detectable leaky degradation. Finally, we show that the degradation of ERM-1, a highly stable protein that is challenging to deplete, could be improved further by using multiple mIAA7 degrons. Taken together, the mIAA7 degron further increases the power and applicability of the auxin-inducible degradation system. To facilitate the generation of mIAA7-tagged proteins using CRISPR/Cas9 genome engineering, we generated a toolkit of plasmids for the generation of dsDNA repair templates by PCR.
Collapse
Affiliation(s)
- Jorian J Sepers
- Division of Developmental Biology, Institute of Biodynamics and Biocomplexity, Department of Biology, Faculty of Science, Utrecht University, 3584 CH Utrecht, The Netherlands
| | - Noud H M Verstappen
- Division of Developmental Biology, Institute of Biodynamics and Biocomplexity, Department of Biology, Faculty of Science, Utrecht University, 3584 CH Utrecht, The Netherlands
| | - An A Vo
- Department of Molecular, Cell, and Developmental Biology, University of California-Santa Cruz, Santa Cruz, CA 95064, USA
| | - James Matthew Ragle
- Department of Molecular, Cell, and Developmental Biology, University of California-Santa Cruz, Santa Cruz, CA 95064, USA
| | - Suzan Ruijtenberg
- Division of Developmental Biology, Institute of Biodynamics and Biocomplexity, Department of Biology, Faculty of Science, Utrecht University, 3584 CH Utrecht, The Netherlands
| | - Jordan D Ward
- Department of Molecular, Cell, and Developmental Biology, University of California-Santa Cruz, Santa Cruz, CA 95064, USA
| | - Mike Boxem
- Division of Developmental Biology, Institute of Biodynamics and Biocomplexity, Department of Biology, Faculty of Science, Utrecht University, 3584 CH Utrecht, The Netherlands
| |
Collapse
|
11
|
El Mouridi S, Alkhaldi F, Frøkjær-Jensen C. Modular safe-harbor transgene insertion for targeted single-copy and extrachromosomal array integration in Caenorhabditis elegans. G3 (BETHESDA, MD.) 2022; 12:jkac184. [PMID: 35900171 PMCID: PMC9434227 DOI: 10.1093/g3journal/jkac184] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/30/2022] [Accepted: 06/29/2022] [Indexed: 12/02/2022]
Abstract
Efficient and reproducible transgenesis facilitates and accelerates research using genetic model organisms. Here, we describe a modular safe-harbor transgene insertion (MosTI) for use in Caenorhabditis elegans which improves targeted insertion of single-copy transgenes by homology directed repair and targeted integration of extrachromosomal arrays by nonhomologous end-joining. MosTI allows easy conversion between selection markers at insertion site and a collection of universal targeting vectors with commonly used promoters and fluorophores. Insertions are targeted at three permissive safe-harbor intergenic locations and transgenes are reproducibly expressed in somatic and germ cells. Chromosomal integration is mediated by CRISPR/Cas9, and positive selection is based on a set of split markers (unc-119, hygroR, and gfp) where only animals with chromosomal insertions are rescued, resistant to antibiotics, or fluorescent, respectively. Single-copy insertion is efficient using either constitutive or heat-shock inducible Cas9 expression (25-75%) and insertions can be generated from a multiplexed injection mix. Extrachromosomal array integration is also efficient (7-44%) at modular safe-harbor transgene insertion landing sites or at the endogenous unc-119 locus. We use short-read sequencing to estimate the plasmid copy numbers for 8 integrated arrays (6-37 copies) and long-read Nanopore sequencing to determine the structure and size (5.4 Mb) of 1 array. Using universal targeting vectors, standardized insertion strains, and optimized protocols, it is possible to construct complex transgenic strains which should facilitate the study of increasingly complex biological problems in C. elegans.
Collapse
Affiliation(s)
- Sonia El Mouridi
- Biological and Environmental Sciences and Engineering Division (BESE), King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Kingdom of Saudi Arabia
| | - Faisal Alkhaldi
- Biological and Environmental Sciences and Engineering Division (BESE), King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Kingdom of Saudi Arabia
| | - Christian Frøkjær-Jensen
- Biological and Environmental Sciences and Engineering Division (BESE), King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Kingdom of Saudi Arabia
| |
Collapse
|
12
|
Endocytosis in the axon initial segment maintains neuronal polarity. Nature 2022; 609:128-135. [PMID: 35978188 PMCID: PMC9433327 DOI: 10.1038/s41586-022-05074-5] [Citation(s) in RCA: 20] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2021] [Accepted: 07/05/2022] [Indexed: 11/09/2022]
Abstract
Neurons are highly polarized cells that face the fundamental challenge of compartmentalizing a vast and diverse repertoire of proteins in order to function properly1. The axon initial segment (AIS) is a specialized domain that separates a neuron’s morphologically, biochemically and functionally distinct axon and dendrite compartments2,3. How the AIS maintains polarity between these compartments is not fully understood. Here we find that in Caenorhabditis elegans, mouse, rat and human neurons, dendritically and axonally polarized transmembrane proteins are recognized by endocytic machinery in the AIS, robustly endocytosed and targeted to late endosomes for degradation. Forcing receptor interaction with the AIS master organizer, ankyrinG, antagonizes receptor endocytosis in the AIS, causes receptor accumulation in the AIS, and leads to polarity deficits with subsequent morphological and behavioural defects. Therefore, endocytic removal of polarized receptors that diffuse into the AIS serves as a membrane-clearance mechanism that is likely to work in conjunction with the known AIS diffusion-barrier mechanism to maintain neuronal polarity on the plasma membrane. Our results reveal a conserved endocytic clearance mechanism in the AIS to maintain neuronal polarity by reinforcing axonal and dendritic compartment membrane boundaries. Endocytosis and degradation of plasma membrane proteins in the axon initial segment, together with the diffusion-barrier mechanism, maintain a polarized distribution of plasma membrane proteins in Caenorhabditis elegans, mouse, rat and human neurons.
Collapse
|
13
|
Holzer E, Rumpf-Kienzl C, Falk S, Dammermann A. A modified TurboID approach identifies tissue-specific centriolar components in C. elegans. PLoS Genet 2022; 18:e1010150. [PMID: 35442950 PMCID: PMC9020716 DOI: 10.1371/journal.pgen.1010150] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2022] [Accepted: 03/15/2022] [Indexed: 01/26/2023] Open
Abstract
Proximity-dependent labeling approaches such as BioID have been a great boon to studies of protein-protein interactions in the context of cytoskeletal structures such as centrosomes which are poorly amenable to traditional biochemical approaches like immunoprecipitation and tandem affinity purification. Yet, these methods have so far not been applied extensively to invertebrate experimental models such as C. elegans given the long labeling times required for the original promiscuous biotin ligase variant BirA*. Here, we show that the recently developed variant TurboID successfully probes the interactomes of both stably associated (SPD-5) and dynamically localized (PLK-1) centrosomal components. We further develop an indirect proximity labeling method employing a GFP nanobody-TurboID fusion, which allows the identification of protein interactors in a tissue-specific manner in the context of the whole animal. Critically, this approach utilizes available endogenous GFP fusions, avoiding the need to generate multiple additional strains for each target protein and the potential complications associated with overexpressing the protein from transgenes. Using this method, we identify homologs of two highly conserved centriolar components, Cep97 and BLD10/Cep135, which are present in various somatic tissues of the worm. Surprisingly, neither protein is expressed in early embryos, likely explaining why these proteins have escaped attention until now. Our work expands the experimental repertoire for C. elegans and opens the door for further studies of tissue-specific variation in centrosome architecture.
Collapse
Affiliation(s)
- Elisabeth Holzer
- Max Perutz Labs, University of Vienna, Vienna Biocenter (VBC), Vienna, Austria
| | | | - Sebastian Falk
- Max Perutz Labs, University of Vienna, Vienna Biocenter (VBC), Vienna, Austria
| | - Alexander Dammermann
- Max Perutz Labs, University of Vienna, Vienna Biocenter (VBC), Vienna, Austria
- * E-mail:
| |
Collapse
|
14
|
A DNA replication-independent function of pre-replication complex genes during cell invasion in C. elegans. PLoS Biol 2022; 20:e3001317. [PMID: 35192608 PMCID: PMC8863262 DOI: 10.1371/journal.pbio.3001317] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2021] [Accepted: 12/01/2021] [Indexed: 11/19/2022] Open
Abstract
Cell invasion is an initiating event during tumor cell metastasis and an essential process during development. A screen of C. elegans orthologs of genes overexpressed in invasive human melanoma cells has identified several components of the conserved DNA pre-replication complex (pre-RC) as positive regulators of anchor cell (AC) invasion. The pre-RC genes function cell-autonomously in the G1-arrested AC to promote invasion, independently of their role in licensing DNA replication origins in proliferating cells. While the helicase activity of the pre-RC is necessary for AC invasion, the downstream acting DNA replication initiation factors are not required. The pre-RC promotes the invasive fate by regulating the expression of extracellular matrix genes and components of the PI3K signaling pathway. Increasing PI3K pathway activity partially suppressed the AC invasion defects caused by pre-RC depletion, suggesting that the PI3K pathway is one critical pre-RC target. We propose that the pre-RC, or a part of it, acts in the postmitotic AC as a transcriptional regulator that facilitates the switch to an invasive phenotype.
Collapse
|
15
|
Hills-Muckey K, Martinez MAQ, Stec N, Hebbar S, Saldanha J, Medwig-Kinney TN, Moore FEQ, Ivanova M, Morao A, Ward JD, Moss EG, Ercan S, Zinovyeva AY, Matus DQ, Hammell CM. An engineered, orthogonal auxin analog/AtTIR1(F79G) pairing improves both specificity and efficacy of the auxin degradation system in Caenorhabditis elegans. Genetics 2022; 220:iyab174. [PMID: 34739048 PMCID: PMC9097248 DOI: 10.1093/genetics/iyab174] [Citation(s) in RCA: 23] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2021] [Accepted: 09/17/2021] [Indexed: 02/06/2023] Open
Abstract
The auxin-inducible degradation system in C. elegans allows for spatial and temporal control of protein degradation via heterologous expression of a single Arabidopsis thaliana F-box protein, transport inhibitor response 1 (AtTIR1). In this system, exogenous auxin (Indole-3-acetic acid; IAA) enhances the ability of AtTIR1 to function as a substrate recognition component that adapts engineered degron-tagged proteins to the endogenous C. elegans E3 ubiquitin ligases complex [SKR-1/2-CUL-1-F-box (SCF)], targeting them for degradation by the proteosome. While this system has been employed to dissect the developmental functions of many C. elegans proteins, we have found that several auxin-inducible degron (AID)-tagged proteins are constitutively degraded by AtTIR1 in the absence of auxin, leading to undesired loss-of-function phenotypes. In this manuscript, we adapt an orthogonal auxin derivative/mutant AtTIR1 pair [C. elegans AID version 2 (C.e.AIDv2)] that transforms the specificity of allosteric regulation of TIR1 from IAA to one that is dependent on an auxin derivative harboring a bulky aryl group (5-Ph-IAA). We find that a mutant AtTIR1(F79G) allele that alters the ligand-binding interface of TIR1 dramatically reduces ligand-independent degradation of multiple AID*-tagged proteins. In addition to solving the ectopic degradation problem for some AID-targets, the addition of 5-Ph-IAA to culture media of animals expressing AtTIR1(F79G) leads to more penetrant loss-of-function phenotypes for AID*-tagged proteins than those elicited by the AtTIR1-IAA pairing at similar auxin analog concentrations. The improved specificity and efficacy afforded by the mutant AtTIR1(F79G) allele expand the utility of the AID system and broaden the number of proteins that can be effectively targeted with it.
Collapse
Affiliation(s)
| | - Michael A Q Martinez
- Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, NY 11794, USA
| | - Natalia Stec
- Cold Spring Harbor Laboratory, Cold Spring Harbor, NY 11724, USA
| | - Shilpa Hebbar
- Division of Biology, Kansas State University, Manhattan, KS 66506, USA
| | - Joanne Saldanha
- Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, NY 11794, USA
| | - Taylor N Medwig-Kinney
- Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, NY 11794, USA
| | - Frances E Q Moore
- Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, NY 11794, USA
| | - Maria Ivanova
- Department of Molecular Biology, Rowan University, Stratford, NJ 08084, USA
| | - Ana Morao
- Center for Genomics and Systems Biology, New York University, New York, NY 10003, USA
| | - J D Ward
- Department of Molecular, Cell, and Developmental Biology, University of California-Santa Cruz, Santa Cruz, CA 95064, USA
| | - Eric G Moss
- Department of Molecular Biology, Rowan University, Stratford, NJ 08084, USA
| | - Sevinc Ercan
- Center for Genomics and Systems Biology, New York University, New York, NY 10003, USA
| | - Anna Y Zinovyeva
- Division of Biology, Kansas State University, Manhattan, KS 66506, USA
| | - David Q Matus
- Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, NY 11794, USA
| | | |
Collapse
|
16
|
Floxed exon (Flexon): A flexibly positioned stop cassette for recombinase-mediated conditional gene expression. Proc Natl Acad Sci U S A 2022; 119:2117451119. [PMID: 35027456 PMCID: PMC8784106 DOI: 10.1073/pnas.2117451119] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/04/2021] [Indexed: 12/15/2022] Open
Abstract
Tools that afford spatiotemporal control of gene expression are crucial for studying genes and processes in multicellular organisms. Stop cassettes consist of exogenous sequences that interrupt gene expression and flanking site-specific recombinase sites to allow for tissue-specific excision and restoration of function by expression of the cognate recombinase. We describe a stop cassette called a flexon, composed of an artificial exon flanked by artificial introns that can be flexibly positioned in a gene. We demonstrate its efficacy in Caenorhabditis elegans for lineage-specific control of gene expression and for tissue-specific RNA interference and discuss other potential uses. The Flexon approach should be feasible in any system amenable to site-specific recombination-based methods and applicable to diverse areas including development, neuroscience, and metabolism. Conditional gene expression is a powerful tool for genetic analysis of biological phenomena. In the widely used “lox-stop-lox” approach, insertion of a stop cassette consisting of a series of stop codons and polyadenylation signals flanked by lox sites into the 5′ untranslated region (UTR) of a gene prevents expression until the cassette is excised by tissue-specific expression of Cre recombinase. Although lox-stop-lox and similar approaches using other site-specific recombinases have been successfully used in many experimental systems, this design has certain limitations. Here, we describe the Floxed exon (Flexon) approach, which uses a stop cassette composed of an artificial exon flanked by artificial introns, designed to cause premature termination of translation and nonsense-mediated decay of the mRNA and allowing for flexible placement into a gene. We demonstrate its efficacy in Caenorhabditis elegans by showing that, when promoters that cause weak and/or transient cell-specific expression are used to drive Cre in combination with a gfp(flexon) transgene, strong and sustained expression of green fluorescent protein (GFP) is obtained in specific lineages. We also demonstrate its efficacy in an endogenous gene context: we inserted a flexon into the Argonaute gene rde-1 to abrogate RNA interference (RNAi), and restored RNAi tissue specifically by expression of Cre. Finally, we describe several potential additional applications of the Flexon approach, including more precise control of gene expression using intersectional methods, tissue-specific protein degradation, and generation of genetic mosaics. The Flexon approach should be feasible in any system where a site-specific recombination-based method may be applied.
Collapse
|
17
|
Trojanowski NF, Fang-Yen C. Optogenetic Perturbation of Individual C. elegans Pharyngeal Neurons While Monitoring Feeding Behavior. Methods Mol Biol 2022; 2468:117-131. [PMID: 35320563 DOI: 10.1007/978-1-0716-2181-3_7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Optogenetic approaches have proven to be powerful for examining the roles of specific neurons in generating behaviors, especially in systems where electrophysiological manipulation is not possible. Here we describe a method for optogenetically manipulating single pharyngeal neurons in intact C. elegans while monitoring pharyngeal behavior. This approach provides bidirectional and dynamic control of pharyngeal neural activity while quantitatively assessing behavior and has allowed us to test hypotheses about the roles of individual pharyngeal neurons in feeding behavior.
Collapse
Affiliation(s)
- Nicholas F Trojanowski
- Department of Bioengineering, School of Engineering and Applied Science, University of Pennsylvania, Philadelphia, PA, USA
- Department of Neuroscience, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
- Department of Biology, Brandeis University, Waltham, MA, USA
| | - Christopher Fang-Yen
- Department of Bioengineering, School of Engineering and Applied Science, University of Pennsylvania, Philadelphia, PA, USA.
- Department of Neuroscience, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA.
| |
Collapse
|
18
|
Bergs A, Henss T, Glock C, Nagpal J, Gottschalk A. Microbial Rhodopsin Optogenetic Tools: Application for Analyses of Synaptic Transmission and of Neuronal Network Activity in Behavior. Methods Mol Biol 2022; 2468:89-115. [PMID: 35320562 DOI: 10.1007/978-1-0716-2181-3_6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Over the past 15 years, optogenetic methods have revolutionized neuroscientific and cell biological research, also in the nematode Caenorhabditis elegans. In this chapter, we give an update about current optogenetic tools and methods to address neuronal activity and inhibition, as well as second messenger signaling, based on microbial rhodopsins. We address channelrhodopsins and variants thereof, which conduct cations or anions, for depolarization and hyperpolarization of the membrane potential. Also, we cover ion pumping rhodopsins, like halorhodopsin, Mac, and Arch. A recent addition to rhodopsin-based optogenetics is voltage imaging tools that allow fluorescent readout of membrane voltage (directly, via fluorescence of the rhodopsin chromophore retinal, or indirectly, via electrochromic FRET). Last, we report on a new addition to the optogenetic toolbox, which is rhodopsin guanylyl cyclases, as well as mutated variants with specificity for cyclic AMP. These can be used to regulate intracellular levels of cGMP and cAMP, which are important second messengers in sensory and other neurons. We further show how they can be combined with cyclic nucleotide-gated channels in two-component optogenetics, for depolarization or hyperpolarization of membrane potential. For all tools, we present protocols for straightforward experimentation to address neuronal activation and inhibition, particularly at the neuromuscular junction, and for combined optogenetic actuation and Ca2+ imaging. We also provide protocols for usage of rhodopsin guanylyl and adenylyl cyclases. Finally, we list a number of points to consider when designing and conducting rhodopsin-based optogenetic experiments.
Collapse
Affiliation(s)
- Amelie Bergs
- Buchmann Institute for Molecular Life Sciences, Goethe University, Frankfurt, Germany
- Institute of Biophysical Chemistry, Goethe University, Frankfurt, Germany
| | - Thilo Henss
- Buchmann Institute for Molecular Life Sciences, Goethe University, Frankfurt, Germany
- Institute of Biophysical Chemistry, Goethe University, Frankfurt, Germany
| | - Caspar Glock
- Buchmann Institute for Molecular Life Sciences, Goethe University, Frankfurt, Germany
- Institute of Biophysical Chemistry, Goethe University, Frankfurt, Germany
- Max-Planck-Institute for Brain Research, Frankfurt, Germany
| | - Jatin Nagpal
- Buchmann Institute for Molecular Life Sciences, Goethe University, Frankfurt, Germany
- Institute of Biophysical Chemistry, Goethe University, Frankfurt, Germany
- APC Microbiome Ireland, University College Cork, Cork, Ireland
| | - Alexander Gottschalk
- Buchmann Institute for Molecular Life Sciences, Goethe University, Frankfurt, Germany.
- Institute of Biophysical Chemistry, Goethe University, Frankfurt, Germany.
| |
Collapse
|
19
|
Katz M. Genetic Methods for Cellular Manipulation in C. elegans. Methods Mol Biol 2022; 2468:51-72. [PMID: 35320560 DOI: 10.1007/978-1-0716-2181-3_4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Neuron manipulation in vivo by ablation, activation or inactivation, and regulation of gene expression is essential for dissecting nervous system function. Here we describe genetic means for neuron manipulation in the nematode C. elegans, and provide protocols for generating transgenic animals containing these genetic tools.
Collapse
Affiliation(s)
- Menachem Katz
- Department of Biology, Technion- Israel Institute of Technology, Haifa, Israel.
| |
Collapse
|
20
|
Li Y, Walker LA, Zhao Y, Edwards EM, Michki NS, Cheng HPJ, Ghazzi M, Chen TY, Chen M, Roossien DH, Cai D. Bitbow Enables Highly Efficient Neuronal Lineage Tracing and Morphology Reconstruction in Single Drosophila Brains. Front Neural Circuits 2021; 15:732183. [PMID: 34744636 PMCID: PMC8564373 DOI: 10.3389/fncir.2021.732183] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2021] [Accepted: 09/14/2021] [Indexed: 12/15/2022] Open
Abstract
Identifying the cellular origins and mapping the dendritic and axonal arbors of neurons have been century old quests to understand the heterogeneity among these brain cells. Current Brainbow based transgenic animals take the advantage of multispectral labeling to differentiate neighboring cells or lineages, however, their applications are limited by the color capacity. To improve the analysis throughput, we designed Bitbow, a digital format of Brainbow which exponentially expands the color palette to provide tens of thousands of spectrally resolved unique labels. We generated transgenic Bitbow Drosophila lines, established statistical tools, and streamlined sample preparation, image processing, and data analysis pipelines to conveniently mapping neural lineages, studying neuronal morphology and revealing neural network patterns with unprecedented speed, scale, and resolution.
Collapse
Affiliation(s)
- Ye Li
- Department of Cell and Developmental Biology, University of Michigan, Ann Arbor, MI, United States
| | - Logan A Walker
- Biophysics LS&A, University of Michigan, Ann Arbor, MI, United States
| | - Yimeng Zhao
- Department of Cell and Developmental Biology, University of Michigan, Ann Arbor, MI, United States
| | - Erica M Edwards
- Department of Cell and Developmental Biology, University of Michigan, Ann Arbor, MI, United States
| | - Nigel S Michki
- Biophysics LS&A, University of Michigan, Ann Arbor, MI, United States
| | - Hon Pong Jimmy Cheng
- Department of Cell and Developmental Biology, University of Michigan, Ann Arbor, MI, United States
| | - Marya Ghazzi
- Department of Cell and Developmental Biology, University of Michigan, Ann Arbor, MI, United States
| | - Tiffany Y Chen
- Department of Cell and Developmental Biology, University of Michigan, Ann Arbor, MI, United States
| | - Maggie Chen
- Department of Cell and Developmental Biology, University of Michigan, Ann Arbor, MI, United States
| | - Douglas H Roossien
- Department of Cell and Developmental Biology, University of Michigan, Ann Arbor, MI, United States
| | - Dawen Cai
- Department of Cell and Developmental Biology, University of Michigan, Ann Arbor, MI, United States.,Biophysics LS&A, University of Michigan, Ann Arbor, MI, United States.,Neuroscience Graduate Program, University of Michigan, Ann Arbor, MI, United States
| |
Collapse
|
21
|
Russell JC, Lei H, Chaliparambil RK, Fish S, Markiewicz SM, Lee TI, Noori A, Kaeberlein M. Generation and characterization of a tractable C. elegans model of tauopathy. GeroScience 2021; 43:2621-2631. [PMID: 34536202 PMCID: PMC8599767 DOI: 10.1007/s11357-021-00436-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2021] [Accepted: 08/09/2021] [Indexed: 12/20/2022] Open
Abstract
Alzheimer's disease(AD) is an age-associated neurodegenerative disease that results in deterioration of memory and cognitive function. As a currently untreatable disorder, AD has emerged as one of the defining biomedical challenges of our time. Thus, new approaches that can examine the cellular and molecular mechanisms underlying age-related AD pathology are sorely needed. One of the hallmarks of Alzheimer's disease is the hyperphosphorylation of the tau protein. Caenorhabditis elegans have been previously used to study the genetic pathways impacted by tau proteotoxic stress; however, currently, available C. elegans tau models express the human protein solely in neurons, which are unresponsive to global RNA interference (RNAi). This limits powerful RNAi screening methods from being utilized effectively in these disease models. Our goal was to develop a C. elegans tau model that has pronounced tau-induced disease phenotypes in cells that can be modified by feeding RNAi methods. Towards this end, we generated a novel C. elegans transgenic line with codon-optimized human 0N4R V337M tau expressed in the body wall muscle under the myo-3 promoter. Immunoblotting experiments revealed that the expressed tau is phosphorylated on epitopes canonically associated with human AD pathology. The tau line has significantly reduced health metrics, including egg laying, growth rate, paralysis, thrashing frequency, crawling speed, and lifespan. These defects are suppressed by RNAi directed against the tau mRNA. Taken together, our results suggest that this alternative tau genetic model could be a useful tool for uncovering the mechanisms that influence the hyperphosphorylation and toxicity of human tau via RNAi screening and other approaches.
Collapse
Affiliation(s)
- Joshua C Russell
- Department of Laboratory Medicine & Pathology, University of Washington, Seattle, WA, USA.
| | - Haoyi Lei
- Department of Laboratory Medicine & Pathology, University of Washington, Seattle, WA, USA
| | - Rahul K Chaliparambil
- Department of Laboratory Medicine & Pathology, University of Washington, Seattle, WA, USA
| | | | | | - Ting-I Lee
- Department of Laboratory Medicine & Pathology, University of Washington, Seattle, WA, USA
| | | | - Matt Kaeberlein
- Department of Laboratory Medicine & Pathology, University of Washington, Seattle, WA, USA.
| |
Collapse
|
22
|
Driesschaert B, Mergan L, Temmerman L. Conditional gene expression in invertebrate animal models. J Genet Genomics 2021; 48:14-31. [PMID: 33814307 DOI: 10.1016/j.jgg.2021.01.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2020] [Revised: 12/11/2020] [Accepted: 01/08/2021] [Indexed: 10/22/2022]
Abstract
A mechanistic understanding of biology requires appreciating spatiotemporal aspects of gene expression and its functional implications. Conditional expression allows for (ir)reversible switching of genes on or off, with the potential of spatial and/or temporal control. This provides a valuable complement to the more often used constitutive gene (in)activation through mutagenesis, providing tools to answer a wider array of research questions across biological disciplines. Spatial and/or temporal control are granted primarily by (combinations of) specific promoters, temperature regimens, compound addition, or illumination. The use of such genetic tool kits is particularly widespread in invertebrate animal models because they can be applied to study biological processes in short time frames and on large scales, using organisms amenable to easy genetic manipulation. Recent years witnessed an exciting expansion and optimization of such tools, of which we provide a comprehensive overview and discussion regarding their use in invertebrates. The mechanism, applicability, benefits, and drawbacks of each of the systems, as well as further developments to be expected in the foreseeable future, are highlighted.
Collapse
Affiliation(s)
- Brecht Driesschaert
- Animal Physiology and Neurobiology, Department of Biology, University of Leuven (KU Leuven), Naamsestraat 59 - Box 2465, B-3000 Leuven, Belgium
| | - Lucas Mergan
- Animal Physiology and Neurobiology, Department of Biology, University of Leuven (KU Leuven), Naamsestraat 59 - Box 2465, B-3000 Leuven, Belgium
| | - Liesbet Temmerman
- Animal Physiology and Neurobiology, Department of Biology, University of Leuven (KU Leuven), Naamsestraat 59 - Box 2465, B-3000 Leuven, Belgium.
| |
Collapse
|
23
|
Aljohani MD, El Mouridi S, Priyadarshini M, Vargas-Velazquez AM, Frøkjær-Jensen C. Engineering rules that minimize germline silencing of transgenes in simple extrachromosomal arrays in C. elegans. Nat Commun 2020; 11:6300. [PMID: 33298957 PMCID: PMC7725773 DOI: 10.1038/s41467-020-19898-0] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2020] [Accepted: 11/05/2020] [Indexed: 12/29/2022] Open
Abstract
Transgenes are prone to progressive silencing due to their structure, copy number, and genomic location. In C. elegans, repressive mechanisms are particularly strong in the germline with almost fully penetrant transgene silencing in simple extrachromosomal arrays and frequent silencing of single-copy transgene insertions. A class of non-coding DNA, Periodic An/Tn Clusters (PATCs) can prevent transgene-silencing in repressive chromatin or from small interfering RNAs (piRNAs). Here, we describe design rules (codon-optimization, intron and PATC inclusion, elevated temperature (25 °C), and vector backbone removal) for efficient germline expression from arrays in wildtype animals. We generate web-based tools to analyze PATCs and reagents for the convenient assembly of PATC-rich transgenes. An extensive collection of silencing resistant fluorescent proteins (e.g., gfp, mCherry, and tagBFP) can be used for dissecting germline regulatory elements and a set of enhanced enzymes (Mos1 transposase, Cas9, Cre, and Flp recombinases) enable efficient genetic engineering in C. elegans.
Collapse
Affiliation(s)
- Mohammed D Aljohani
- King Abdullah University of Science and Technology (KAUST), Biological and Environmental Science and Engineering Division (BESE), KAUST Environmental Epigenetics Program (KEEP), Thuwal, 23955-6900, Saudi Arabia
| | - Sonia El Mouridi
- King Abdullah University of Science and Technology (KAUST), Biological and Environmental Science and Engineering Division (BESE), KAUST Environmental Epigenetics Program (KEEP), Thuwal, 23955-6900, Saudi Arabia
| | - Monika Priyadarshini
- King Abdullah University of Science and Technology (KAUST), Biological and Environmental Science and Engineering Division (BESE), KAUST Environmental Epigenetics Program (KEEP), Thuwal, 23955-6900, Saudi Arabia
| | - Amhed M Vargas-Velazquez
- King Abdullah University of Science and Technology (KAUST), Biological and Environmental Science and Engineering Division (BESE), KAUST Environmental Epigenetics Program (KEEP), Thuwal, 23955-6900, Saudi Arabia
| | - Christian Frøkjær-Jensen
- King Abdullah University of Science and Technology (KAUST), Biological and Environmental Science and Engineering Division (BESE), KAUST Environmental Epigenetics Program (KEEP), Thuwal, 23955-6900, Saudi Arabia.
| |
Collapse
|
24
|
Signal Decoding for Glutamate Modulating Egg Laying Oppositely in Caenorhabditis elegans under Varied Environmental Conditions. iScience 2020; 23:101588. [PMID: 33089099 PMCID: PMC7567941 DOI: 10.1016/j.isci.2020.101588] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2020] [Revised: 08/07/2020] [Accepted: 09/16/2020] [Indexed: 11/24/2022] Open
Abstract
Animals' ability to sense environmental cues and to integrate this information to control fecundity is vital for continuing the species lineage. In this study, we observed that the sensory neurons Amphid neuron (ASHs and ADLs) differentially regulate egg-laying behavior in Caenorhabditis elegans under varied environmental conditions via distinct neuronal circuits. Under standard culture conditions, ASHs tonically release a small amount of glutamate and inhibit Hermaphrodite specific motor neuron (HSN) activities and egg laying via a highly sensitive Glutamate receptor (GLR)-5 receptor. In contrast, under Cu2+ stimulation, ASHs and ADLs may release a large amount of glutamate and inhibit Amphid interneuron (AIA) interneurons via low-sensitivity Glutamate-gated chloride channel (GLC)-3 receptor, thus removing the inhibitory roles of AIAs on HSN activity and egg laying. However, directly measuring the amount of glutamate released by sensory neurons under different conditions and assaying the binding kinetics of receptors with the neurotransmitter are still required to support this study directly. Short-term exposure of CuSO4 evokes hyperactive egg laying ASHs inhibit HSNs and egg laying via GLR-5 receptor under no Cu2+ treatment AIA interneurons suppress HSNs and thus egg laying through ACR-14 signaling Under noxious Cu2+ treatment, ASHs and ADLs suppress AIAs and augment egg laying
Collapse
|
25
|
Ge MH, Wang W, Wu TH, Wen X, Al-Sheikh U, Chen LL, Yin SW, Wu JJ, Huang JH, He QQ, Liu H, Li R, Wang PZ, Wu ZX. Dual Recombining-out System for Spatiotemporal Gene Expression in C. elegans. iScience 2020; 23:101567. [PMID: 33083734 PMCID: PMC7549056 DOI: 10.1016/j.isci.2020.101567] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2020] [Revised: 08/12/2020] [Accepted: 09/11/2020] [Indexed: 01/01/2023] Open
Abstract
Specific recording, labeling, and spatiotemporal manipulating neurons are essential for neuroscience research. In this study, we developed a tripartite spatiotemporal gene induction system in C. elegans, which is based on the knockout of two transcriptional terminators (stops in short) by two different recombinases FLP and CRE. The recombinase sites (loxP and FRT) flanked stops after a ubiquitous promoter terminate transcription of target genes. FLP and CRE, induced by two promoters of overlapping expression, remove the stops (subsequent FLP/CRE-out). The system provides an "AND" gate strategy for specific gene expression in single types of cell(s). Combined with an inducible promoter or element, the system can control the spatiotemporal expression of genes in defined cell types, especially in cells or tissues lacking a specific promoter. This tripartite FLP/CRE-out gene expression system is a simple, labor- and cost-saving toolbox for cell type-specific and inducible gene expression in C. elegans.
Collapse
Affiliation(s)
- Ming-Hai Ge
- Key Laboratory of Molecular Biophysics of Ministry of Education, Institute of Biophysics and Biochemistry, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, China
| | - Wei Wang
- Key Laboratory of Molecular Biophysics of Ministry of Education, Institute of Biophysics and Biochemistry, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, China
| | - Tai-Hong Wu
- Key Laboratory of Molecular Biophysics of Ministry of Education, Institute of Biophysics and Biochemistry, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, China
| | - Xin Wen
- Key Laboratory of Molecular Biophysics of Ministry of Education, Institute of Biophysics and Biochemistry, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, China
| | - Umar Al-Sheikh
- Key Laboratory of Molecular Biophysics of Ministry of Education, Institute of Biophysics and Biochemistry, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, China
| | - Li-Li Chen
- Key Laboratory of Molecular Biophysics of Ministry of Education, Institute of Biophysics and Biochemistry, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, China
| | - Sheng-Wu Yin
- Key Laboratory of Molecular Biophysics of Ministry of Education, Institute of Biophysics and Biochemistry, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, China
| | - Jing-Jing Wu
- Key Laboratory of Molecular Biophysics of Ministry of Education, Institute of Biophysics and Biochemistry, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, China
| | - Jia-Hao Huang
- Key Laboratory of Molecular Biophysics of Ministry of Education, Institute of Biophysics and Biochemistry, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, China
| | - Qing-Qin He
- Key Laboratory of Molecular Biophysics of Ministry of Education, Institute of Biophysics and Biochemistry, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, China
| | - Hui Liu
- Key Laboratory of Molecular Biophysics of Ministry of Education, Institute of Biophysics and Biochemistry, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, China
| | - Rong Li
- Key Laboratory of Molecular Biophysics of Ministry of Education, Institute of Biophysics and Biochemistry, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, China
| | - Ping-Zhou Wang
- Key Laboratory of Molecular Biophysics of Ministry of Education, Institute of Biophysics and Biochemistry, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, China
| | - Zheng-Xing Wu
- Key Laboratory of Molecular Biophysics of Ministry of Education, Institute of Biophysics and Biochemistry, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, China
| |
Collapse
|
26
|
Leveraging a gain-of-function allele of Caenorhabditis elegans paqr-1 to elucidate membrane homeostasis by PAQR proteins. PLoS Genet 2020; 16:e1008975. [PMID: 32750056 PMCID: PMC7428288 DOI: 10.1371/journal.pgen.1008975] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2020] [Revised: 08/14/2020] [Accepted: 07/01/2020] [Indexed: 12/12/2022] Open
Abstract
The C. elegans proteins PAQR-2 (a homolog of the human seven-transmembrane domain AdipoR1 and AdipoR2 proteins) and IGLR-2 (a homolog of the mammalian LRIG proteins characterized by a single transmembrane domain and the presence of immunoglobulin domains and leucine-rich repeats in their extracellular portion) form a complex that protects against plasma membrane rigidification by promoting the expression of fatty acid desaturases and the incorporation of polyunsaturated fatty acids into phospholipids, hence increasing membrane fluidity. In the present study, we leveraged a novel gain-of-function allele of PAQR-1, a PAQR-2 paralog, to carry out structure-function studies. We found that the transmembrane domains of PAQR-2 are responsible for its functional requirement for IGLR-2, that PAQR-1 does not require IGLR-2 but acts via the same pathway as PAQR-2, and that the divergent N-terminal cytoplasmic domains of the PAQR-1 and PAQR-2 proteins serve a regulatory function and may regulate access to the catalytic site of these proteins. We also show that overexpression of human AdipoR1 or AdipoR2 alone is sufficient to confer increased palmitic acid resistance in HEK293 cells, and thus act in a manner analogous to the PAQR-1 gain-of-function allele.
Collapse
|
27
|
Efficient Transgenesis in Caenorhabditis elegans Using Flp Recombinase-Mediated Cassette Exchange. Genetics 2020; 215:903-921. [PMID: 32513816 DOI: 10.1534/genetics.120.303388] [Citation(s) in RCA: 37] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2020] [Accepted: 05/01/2020] [Indexed: 11/18/2022] Open
Abstract
The application of CRISPR technology has greatly facilitated the creation of transgenic Caenorhabditis elegans lines. However, methods to insert multi-kilobase DNA constructs remain laborious even with these advances. Here, I describe a new approach for introducing large DNA constructs into the C. elegans genome at specific sites using a combination of Flp and Cre recombinases. The system utilizes specialized integrated landing sites that express GFP ubiquitously flanked by single loxP, FRT, and FRT3 sites. DNA sequences of interest are inserted into an integration vector that contains a sqt-1 self-excising cassette and FRT and FRT3 sites. Plasmid DNA is injected into the germline of landing site animals. Transgenic animals are identified as Rol progeny, and the sqt-1 marker is subsequently excised with heat shock Cre expression. Integration events were obtained at a rate of approximately one integration per three injected F0 animals-a rate substantially higher than any current approach. To demonstrate the robustness of the approach, I compared the efficiency of the Gal4/UAS, QF (and QF2)/QUAS, tetR(and rtetR)/tetO, and LexA/lexO bipartite expression systems by assessing expression levels in combinations of driver and reporter GFP constructs and a direct promoter GFP fusion each integrated at multiple sites in the genome. My data demonstrate that all four bipartite systems are functional in C. elegans Although the new integration system has several limitations, it greatly reduces the effort required to create single-copy insertions at defined sites in the C. elegans genome.
Collapse
|
28
|
The Caenorhabditis elegans homolog of the Evi1 proto-oncogene, egl-43, coordinates G1 cell cycle arrest with pro-invasive gene expression during anchor cell invasion. PLoS Genet 2020; 16:e1008470. [PMID: 32203506 PMCID: PMC7117773 DOI: 10.1371/journal.pgen.1008470] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2019] [Revised: 04/02/2020] [Accepted: 02/27/2020] [Indexed: 11/30/2022] Open
Abstract
Cell invasion allows cells to migrate across compartment boundaries formed by basement membranes. Aberrant cell invasion is a first step during the formation of metastases by malignant cancer cells. Anchor cell (AC) invasion in C. elegans is an excellent in vivo model to study the regulation of cell invasion during development. Here, we have examined the function of egl-43, the homolog of the human Evi1 proto-oncogene (also called MECOM), in the invading AC. egl-43 plays a dual role in this process, firstly by imposing a G1 cell cycle arrest to prevent AC proliferation, and secondly, by activating pro-invasive gene expression. We have identified the AP-1 transcription factor fos-1 and the Notch homolog lin-12 as critical egl-43 targets. A positive feedback loop between fos-1 and egl-43 induces pro-invasive gene expression in the AC, while repression of lin-12 Notch expression by egl-43 ensures the G1 cell cycle arrest necessary for invasion. Reducing lin-12 levels in egl-43 depleted animals restored the G1 arrest, while hyperactivation of lin-12 signaling in the differentiated AC was sufficient to induce proliferation. Taken together, our data have identified egl-43 Evi1 as an important factor coordinating cell invasion with cell cycle arrest. Cells invasion is a fundamental biological process that allows cells to cross compartment boundaries and migrate to new locations. Aberrant cell invasion is a first step during the formation of metastases by malignant cancer cells. We have investigated how a specialized cell in the Nematode C. elegans, the so-called anchor cell, can invade into the adjacent epithelium during normal development. Our work has identified an oncogenic transcription factor that controls the expression of specific target genes necessary for cell invasion, and at the same time inhibits the proliferation of the invading anchor cell. These findings shed light on the mechanisms, by which cells decide whether to proliferate or invade.
Collapse
|
29
|
Maluck E, Busack I, Besseling J, Masurat F, Turek M, Busch KE, Bringmann H. A wake-active locomotion circuit depolarizes a sleep-active neuron to switch on sleep. PLoS Biol 2020; 18:e3000361. [PMID: 32078631 PMCID: PMC7053779 DOI: 10.1371/journal.pbio.3000361] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2019] [Revised: 03/03/2020] [Accepted: 01/23/2020] [Indexed: 11/18/2022] Open
Abstract
Sleep-active neurons depolarize during sleep to suppress wakefulness circuits. Wake-active wake-promoting neurons in turn shut down sleep-active neurons, thus forming a bipartite flip-flop switch. However, how sleep is switched on is unclear because it is not known how wakefulness is translated into sleep-active neuron depolarization when the system is set to sleep. Using optogenetics in Caenorhabditis elegans, we solved the presynaptic circuit for depolarization of the sleep-active RIS neuron during developmentally regulated sleep, also known as lethargus. Surprisingly, we found that RIS activation requires neurons that have known roles in wakefulness and locomotion behavior. The RIM interneurons—which are active during and can induce reverse locomotion—play a complex role and can act as inhibitors of RIS when they are strongly depolarized and as activators of RIS when they are modestly depolarized. The PVC command interneurons, which are known to promote forward locomotion during wakefulness, act as major activators of RIS. The properties of these locomotion neurons are modulated during lethargus. The RIMs become less excitable. The PVCs become resistant to inhibition and have an increased capacity to activate RIS. Separate activation of neither the PVCs nor the RIMs appears to be sufficient for sleep induction; instead, our data suggest that they act in concert to activate RIS. Forward and reverse circuit activity is normally mutually exclusive. Our data suggest that RIS may be activated at the transition between forward and reverse locomotion states, perhaps when both forward (PVC) and reverse (including RIM) circuit activity overlap. While RIS is not strongly activated outside of lethargus, altered activity of the locomotion interneurons during lethargus favors strong RIS activation and thus sleep. The control of sleep-active neurons by locomotion circuits suggests that sleep control may have evolved from locomotion control. The flip-flop sleep switch in C. elegans thus requires an additional component, wake-active sleep-promoting neurons that translate wakefulness into the depolarization of a sleep-active neuron when the worm is sleepy. Wake-active sleep-promoting circuits may also be required for sleep state switching in other animals, including in mammals. This study in nematodes shows that to understand sleep state switching, the flip-flop model for sleep regulation needs to be complemented by additional wake-active sleep-promoting neurons that activate sleep-active sleep-promoting neurons to induce sleep.
Collapse
Affiliation(s)
- Elisabeth Maluck
- Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
- University of Marburg, Marburg, Germany
| | - Inka Busack
- Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
- University of Marburg, Marburg, Germany
| | - Judith Besseling
- Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
| | | | - Michal Turek
- Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
| | | | - Henrik Bringmann
- Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
- University of Marburg, Marburg, Germany
- * E-mail:
| |
Collapse
|
30
|
Castelletto ML, Gang SS, Hallem EA. Recent advances in functional genomics for parasitic nematodes of mammals. ACTA ACUST UNITED AC 2020; 223:223/Suppl_1/jeb206482. [PMID: 32034038 DOI: 10.1242/jeb.206482] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Human-parasitic nematodes infect over a quarter of the world's population and are a major cause of morbidity in low-resource settings. Currently available treatments have not been sufficient to eliminate infections in endemic areas, and drug resistance is an increasing concern, making new treatment options a priority. The development of new treatments requires an improved understanding of the basic biology of these nematodes. Specifically, a better understanding of parasitic nematode development, reproduction and behavior may yield novel drug targets or new opportunities for intervention such as repellents or traps. Until recently, our ability to study parasitic nematode biology was limited because few tools were available for their genetic manipulation. This is now changing as a result of recent advances in the large-scale sequencing of nematode genomes and the development of new techniques for their genetic manipulation. Notably, skin-penetrating gastrointestinal nematodes in the genus Strongyloides are now amenable to transgenesis, RNAi and CRISPR/Cas9-mediated targeted mutagenesis, positioning the Strongyloides species as model parasitic nematode systems. A number of other mammalian-parasitic nematodes, including the giant roundworm Ascaris suum and the tissue-dwelling filarial nematode Brugia malayi, are also now amenable to transgenesis and/or RNAi in some contexts. Using these tools, recent studies of Strongyloides species have already provided insight into the molecular pathways that control the developmental decision to form infective larvae and that drive the host-seeking behaviors of infective larvae. Ultimately, a mechanistic understanding of these processes could lead to the development of new avenues for nematode control.
Collapse
Affiliation(s)
- Michelle L Castelletto
- Department of Microbiology, Immunology, and Molecular Genetics, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Spencer S Gang
- Division of Biological Sciences, University of California, San Diego, La Jolla, CA 92161, USA
| | - Elissa A Hallem
- Department of Microbiology, Immunology, and Molecular Genetics, University of California, Los Angeles, Los Angeles, CA 90095, USA
| |
Collapse
|
31
|
Martinez MAQ, Kinney BA, Medwig-Kinney TN, Ashley G, Ragle JM, Johnson L, Aguilera J, Hammell CM, Ward JD, Matus DQ. Rapid Degradation of Caenorhabditis elegans Proteins at Single-Cell Resolution with a Synthetic Auxin. G3 (BETHESDA, MD.) 2020; 10:267-280. [PMID: 31727633 PMCID: PMC6945041 DOI: 10.1534/g3.119.400781] [Citation(s) in RCA: 47] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/27/2019] [Accepted: 11/12/2019] [Indexed: 12/20/2022]
Abstract
As developmental biologists in the age of genome editing, we now have access to an ever-increasing array of tools to manipulate endogenous gene expression. The auxin-inducible degradation system allows for spatial and temporal control of protein degradation via a hormone-inducible Arabidopsis F-box protein, transport inhibitor response 1 (TIR1). In the presence of auxin, TIR1 serves as a substrate-recognition component of the E3 ubiquitin ligase complex SKP1-CUL1-F-box (SCF), ubiquitinating auxin-inducible degron (AID)-tagged proteins for proteasomal degradation. Here, we optimize the Caenorhabditis elegans AID system by utilizing 1-naphthaleneacetic acid (NAA), an indole-free synthetic analog of the natural auxin indole-3-acetic acid (IAA). We take advantage of the photostability of NAA to demonstrate via quantitative high-resolution microscopy that rapid degradation of target proteins can be detected in single cells within 30 min of exposure. Additionally, we show that NAA works robustly in both standard growth media and physiological buffer. We also demonstrate that K-NAA, the water-soluble, potassium salt of NAA, can be combined with microfluidics for targeted protein degradation in C. elegans larvae. We provide insight into how the AID system functions in C. elegans by determining that TIR1 depends on C. elegans SKR-1/2, CUL-1, and RBX-1 to degrade target proteins. Finally, we present highly penetrant defects from NAA-mediated degradation of the FTZ-F1 nuclear hormone receptor, NHR-25, during C. elegans uterine-vulval development. Together, this work improves our use and understanding of the AID system for dissecting gene function at the single-cell level during C. elegans development.
Collapse
Affiliation(s)
- Michael A Q Martinez
- Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, NY 11794
| | - Brian A Kinney
- Cold Spring Harbor Laboratory, Cold Spring Harbor, NY 11724, and
| | - Taylor N Medwig-Kinney
- Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, NY 11794
| | - Guinevere Ashley
- Department of Molecular, Cell, and Developmental Biology, University of California-Santa Cruz, Santa Cruz, CA 95064
| | - James M Ragle
- Department of Molecular, Cell, and Developmental Biology, University of California-Santa Cruz, Santa Cruz, CA 95064
| | - Londen Johnson
- Department of Molecular, Cell, and Developmental Biology, University of California-Santa Cruz, Santa Cruz, CA 95064
| | - Joseph Aguilera
- Department of Molecular, Cell, and Developmental Biology, University of California-Santa Cruz, Santa Cruz, CA 95064
| | | | - Jordan D Ward
- Department of Molecular, Cell, and Developmental Biology, University of California-Santa Cruz, Santa Cruz, CA 95064
| | - David Q Matus
- Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, NY 11794,
| |
Collapse
|
32
|
Epidermal Growth Factor Signaling Promotes Sleep through a Combined Series and Parallel Neural Circuit. Curr Biol 2019; 30:1-16.e13. [PMID: 31839447 DOI: 10.1016/j.cub.2019.10.048] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2019] [Revised: 07/12/2019] [Accepted: 10/23/2019] [Indexed: 11/20/2022]
Abstract
Sleep requires sleep-active neurons that depolarize to inhibit wake circuits. Sleep-active neurons are under the control of homeostatic mechanisms that determine sleep need. However, little is known about the molecular and circuit mechanisms that translate sleep need into the depolarization of sleep-active neurons. During many stages and conditions in C. elegans, sleep requires a sleep-active neuron called RIS. Here, we defined the transcriptome of RIS and discovered that genes of the epidermal growth factor receptor (EGFR) signaling pathway are expressed in RIS. Because of cellular stress, EGFR directly activates RIS. Activation of EGFR signaling in the ALA neuron has previously been suggested to promote sleep independently of RIS. Unexpectedly, we found that ALA activation promotes RIS depolarization. Our results suggest that ALA is a drowsiness neuron with two separable functions: (1) it inhibits specific behaviors, such as feeding, independently of RIS, (2) and it activates RIS. Whereas ALA plays a strong role in surviving cellular stress, surprisingly, RIS does not. In summary, EGFR signaling can depolarize RIS by an indirect mechanism through activation of the ALA neuron that acts upstream of the sleep-active RIS neuron and through a direct mechanism using EGFR signaling in RIS. ALA-dependent drowsiness, rather than RIS-dependent sleep bouts, appears to be important for increasing survival after cellular stress, suggesting that different types of behavioral inhibition play different roles in restoring health. VIDEO ABSTRACT.
Collapse
|
33
|
Ruiz M, Bodhicharla R, Ståhlman M, Svensk E, Busayavalasa K, Palmgren H, Ruhanen H, Boren J, Pilon M. Evolutionarily conserved long-chain Acyl-CoA synthetases regulate membrane composition and fluidity. eLife 2019; 8:47733. [PMID: 31769755 PMCID: PMC6901333 DOI: 10.7554/elife.47733] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2019] [Accepted: 11/23/2019] [Indexed: 12/19/2022] Open
Abstract
The human AdipoR1 and AdipoR2 proteins, as well as their C. elegans homolog PAQR-2, protect against cell membrane rigidification by exogenous saturated fatty acids by regulating phospholipid composition. Here, we show that mutations in the C. elegans gene acs-13 help to suppress the phenotypes of paqr-2 mutant worms, including their characteristic membrane fluidity defects. acs-13 encodes a homolog of the human acyl-CoA synthetase ACSL1, and localizes to the mitochondrial membrane where it likely activates long chains fatty acids for import and degradation. Using siRNA combined with lipidomics and membrane fluidity assays (FRAP and Laurdan dye staining) we further show that the human ACSL1 potentiates lipotoxicity by the saturated fatty acid palmitate: silencing ACSL1 protects against the membrane rigidifying effects of palmitate and acts as a suppressor of AdipoR2 knockdown, thus echoing the C. elegans findings. We conclude that acs-13 mutations in C. elegans and ACSL1 knockdown in human cells prevent lipotoxicity by promoting increased levels of polyunsaturated fatty acid-containing phospholipids.
Collapse
Affiliation(s)
- Mario Ruiz
- Department of Chemistry and Molecular Biology, University of Gothenburg, Gothenburg, Sweden
| | - Rakesh Bodhicharla
- Department of Chemistry and Molecular Biology, University of Gothenburg, Gothenburg, Sweden
| | - Marcus Ståhlman
- Department of Molecular and Clinical Medicine/Wallenberg Laboratory, Institute of Medicine, University of Gothenburg, Gothenburg, Sweden
| | - Emma Svensk
- Department of Chemistry and Molecular Biology, University of Gothenburg, Gothenburg, Sweden
| | - Kiran Busayavalasa
- Department of Chemistry and Molecular Biology, University of Gothenburg, Gothenburg, Sweden
| | - Henrik Palmgren
- Metabolism BioScience, Cardiovascular, Renal and Metabolism, BioPharmaceuticals R&D, AstraZeneca, Gothenburg, Sweden
| | - Hanna Ruhanen
- Helsinki University Lipidomics Unit, Helsinki Institute for Life Science, Helsinki, Finland.,Molecular and Integrative Biosciences Research Programme, Faculty of Biological and Environmental Sciences, University of Helsinki, Helsinki, Finland
| | - Jan Boren
- Department of Molecular and Clinical Medicine/Wallenberg Laboratory, Institute of Medicine, University of Gothenburg, Gothenburg, Sweden
| | - Marc Pilon
- Department of Chemistry and Molecular Biology, University of Gothenburg, Gothenburg, Sweden
| |
Collapse
|
34
|
Nance J, Frøkjær-Jensen C. The Caenorhabditis elegans Transgenic Toolbox. Genetics 2019; 212:959-990. [PMID: 31405997 PMCID: PMC6707460 DOI: 10.1534/genetics.119.301506] [Citation(s) in RCA: 86] [Impact Index Per Article: 17.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2019] [Accepted: 06/01/2019] [Indexed: 12/30/2022] Open
Abstract
The power of any genetic model organism is derived, in part, from the ease with which gene expression can be manipulated. The short generation time and invariant developmental lineage have made Caenorhabditis elegans very useful for understanding, e.g., developmental programs, basic cell biology, neurobiology, and aging. Over the last decade, the C. elegans transgenic toolbox has expanded considerably, with the addition of a variety of methods to control expression and modify genes with unprecedented resolution. Here, we provide a comprehensive overview of transgenic methods in C. elegans, with an emphasis on recent advances in transposon-mediated transgenesis, CRISPR/Cas9 gene editing, conditional gene and protein inactivation, and bipartite systems for temporal and spatial control of expression.
Collapse
Affiliation(s)
- Jeremy Nance
- Helen L. and Martin S. Kimmel Center for Biology and Medicine, Skirball Institute of Biomolecular Medicine, Department of Cell Biology, New York University School of Medicine, New York 10016
| | - Christian Frøkjær-Jensen
- King Abdullah University of Science and Technology (KAUST), Biological and Environmental Science and Engineering Division (BESE), KAUST Environmental Epigenetics Program (KEEP), Thuwal 23955-6900, Saudi Arabia
| |
Collapse
|
35
|
Wurmthaler LA, Sack M, Gense K, Hartig JS, Gamerdinger M. A tetracycline-dependent ribozyme switch allows conditional induction of gene expression in Caenorhabditis elegans. Nat Commun 2019; 10:491. [PMID: 30700719 PMCID: PMC6353947 DOI: 10.1038/s41467-019-08412-w] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2018] [Accepted: 01/09/2019] [Indexed: 02/05/2023] Open
Abstract
The nematode Caenorhabditis elegans represents an important research model. Convenient methods for conditional induction of gene expression in this organism are not available. Here we describe tetracycline-dependent ribozymes as versatile RNA-based genetic switches in C. elegans. Ribozyme insertion into the 3’-UTR converts any gene of interest into a tetracycline-inducible gene allowing temporal and, by using tissue-selective promoters, spatial control of expression in all developmental stages of the worm. Using the ribozyme switches we established inducible C. elegans polyglutamine Huntington’s disease models exhibiting ligand-controlled polyQ-huntingtin expression, inclusion body formation, and toxicity. Our approach circumvents the complicated expression of regulatory proteins. Moreover, only little coding space is necessary and natural promoters can be utilized. With these advantages tetracycline-dependent ribozymes significantly expand the genetic toolbox for C. elegans. Tools for conditional induction of gene expression in C. elegans are limited compared to other organisms. Here the authors present a tetracycline-dependent ribozyme that allows conditional control of a gene of interest.
Collapse
Affiliation(s)
- Lena A Wurmthaler
- Department of Chemistry, University of Konstanz, 78457, Konstanz, Germany.,Konstanz Research School Chemical Biology (KoRS-CB), University of Konstanz, 78457, Konstanz, Germany
| | - Monika Sack
- Department of Chemistry, University of Konstanz, 78457, Konstanz, Germany.,Konstanz Research School Chemical Biology (KoRS-CB), University of Konstanz, 78457, Konstanz, Germany
| | - Karina Gense
- Konstanz Research School Chemical Biology (KoRS-CB), University of Konstanz, 78457, Konstanz, Germany.,Department of Biology, University of Konstanz, 78457, Konstanz, Germany
| | - Jörg S Hartig
- Department of Chemistry, University of Konstanz, 78457, Konstanz, Germany. .,Konstanz Research School Chemical Biology (KoRS-CB), University of Konstanz, 78457, Konstanz, Germany.
| | - Martin Gamerdinger
- Konstanz Research School Chemical Biology (KoRS-CB), University of Konstanz, 78457, Konstanz, Germany. .,Department of Biology, University of Konstanz, 78457, Konstanz, Germany.
| |
Collapse
|
36
|
A Photoactivatable Botulinum Neurotoxin for Inducible Control of Neurotransmission. Neuron 2019; 101:863-875.e6. [PMID: 30704911 DOI: 10.1016/j.neuron.2019.01.002] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2018] [Revised: 11/14/2018] [Accepted: 12/28/2018] [Indexed: 12/18/2022]
Abstract
Regulated secretion is critical for diverse biological processes ranging from immune and endocrine signaling to synaptic transmission. Botulinum and tetanus neurotoxins, which specifically proteolyze vesicle fusion proteins involved in regulated secretion, have been widely used as experimental tools to block these processes. Genetic expression of these toxins in the nervous system has been a powerful approach for disrupting neurotransmitter release within defined circuitry, but their current utility in the brain and elsewhere remains limited by lack of spatial and temporal control. Here we engineered botulinum neurotoxin B so that it can be activated with blue light. We demonstrate the utility of this approach for inducibly disrupting excitatory neurotransmission, providing a first-in-class optogenetic tool for persistent, light-triggered synaptic inhibition. In addition to blocking neurotransmitter release, this approach will have broad utility for conditionally disrupting regulated secretion of diverse bioactive molecules, including neuropeptides, neuromodulators, hormones, and immune molecules. VIDEO ABSTRACT.
Collapse
|
37
|
Mao S, Qi Y, Zhu H, Huang X, Zou Y, Chi T. A Tet/Q Hybrid System for Robust and Versatile Control of Transgene Expression in C. elegans. iScience 2018; 11:224-237. [PMID: 30634168 PMCID: PMC6327101 DOI: 10.1016/j.isci.2018.12.023] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2018] [Revised: 10/11/2018] [Accepted: 12/20/2018] [Indexed: 11/04/2022] Open
Abstract
Binary gene regulatory tools such as the Tetracycline (Tet)-controlled transcription system have revolutionized genetic research in multiple organisms, but their applications to the worm remain very limited. Here we report that the canonical Tet system is largely inactive in the worm but can be adapted for the worm by introducing multiple modifications, a crucial one being the use of the transcription activation domain from the fungal Q binary system. The resultant Tet/Q hybrid system proves more robust and flexible than either of its precursors, enabling elaborate modes of transgene manipulation previously hard to achieve in the worm, including inducible intersectional regulation and, in combination with the Q system, independent control of distinct transgenes within the same cells. Furthermore, we demonstrated, as an example of its applications, that the hybrid system can tightly and efficiently control Cre expression. This study establishes Tet/Q as a premier binary system for worm genetic research. The popular Tet-controlled gene regulatory system proves inapplicable to the worm The fungal Q binary gene regulatory system is moderately active in the worm A hybrid Tet/Q system is capable of robust, rapid and tunable transgene induction Further modifications enable sophisticated regulation previously hard to achieve
Collapse
Affiliation(s)
- Shaoshuai Mao
- School of Life Sciences and Technology, ShanghaiTech University, Shanghai, China; CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, Shanghai, China; University of Chinese Academy of Sciences, Beijing, China
| | - Yingchuan Qi
- School of Life Sciences and Technology, ShanghaiTech University, Shanghai, China
| | - Huanhu Zhu
- School of Life Sciences and Technology, ShanghaiTech University, Shanghai, China
| | - Xinxin Huang
- School of Life Sciences and Technology, ShanghaiTech University, Shanghai, China; CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, Shanghai, China; University of Chinese Academy of Sciences, Beijing, China
| | - Yan Zou
- School of Life Sciences and Technology, ShanghaiTech University, Shanghai, China
| | - Tian Chi
- School of Life Sciences and Technology, ShanghaiTech University, Shanghai, China; Department Immunobiology, Yale University School of Medicine, New Haven, CT, USA.
| |
Collapse
|
38
|
Ruiz M, Bodhicharla R, Svensk E, Devkota R, Busayavalasa K, Palmgren H, Ståhlman M, Boren J, Pilon M. Membrane fluidity is regulated by the C. elegans transmembrane protein FLD-1 and its human homologs TLCD1/2. eLife 2018; 7:e40686. [PMID: 30509349 PMCID: PMC6279351 DOI: 10.7554/elife.40686] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2018] [Accepted: 11/04/2018] [Indexed: 12/15/2022] Open
Abstract
Dietary fatty acids are the main building blocks for cell membranes in animals, and mechanisms must therefore exist that compensate for dietary variations. We isolated C. elegans mutants that improved tolerance to dietary saturated fat in a sensitized genetic background, including eight alleles of the novel gene fld-1 that encodes a homolog of the human TLCD1 and TLCD2 transmembrane proteins. FLD-1 is localized on plasma membranes and acts by limiting the levels of highly membrane-fluidizing long-chain polyunsaturated fatty acid-containing phospholipids. Human TLCD1/2 also regulate membrane fluidity by limiting the levels of polyunsaturated fatty acid-containing membrane phospholipids. FLD-1 and TLCD1/2 do not regulate the synthesis of long-chain polyunsaturated fatty acids but rather limit their incorporation into phospholipids. We conclude that inhibition of FLD-1 or TLCD1/2 prevents lipotoxicity by allowing increased levels of membrane phospholipids that contain fluidizing long-chain polyunsaturated fatty acids. Editorial note This article has been through an editorial process in which the authors decide how to respond to the issues raised during peer review. The Reviewing Editor's assessment is that all the issues have been addressed (see decision letter).
Collapse
Affiliation(s)
- Mario Ruiz
- Department of Chemistry and Molecular BiologyUniversity of GothenburgGothenburgSweden
| | - Rakesh Bodhicharla
- Department of Chemistry and Molecular BiologyUniversity of GothenburgGothenburgSweden
| | - Emma Svensk
- Department of Chemistry and Molecular BiologyUniversity of GothenburgGothenburgSweden
| | - Ranjan Devkota
- Department of Chemistry and Molecular BiologyUniversity of GothenburgGothenburgSweden
| | - Kiran Busayavalasa
- Department of Chemistry and Molecular BiologyUniversity of GothenburgGothenburgSweden
| | - Henrik Palmgren
- Department of Chemistry and Molecular BiologyUniversity of GothenburgGothenburgSweden
- Diabetes Bioscience, Cardiovascular, Renal and Metabolism, IMED Biotech UnitAstraZenecaGothenburgSweden
| | - Marcus Ståhlman
- Department of Molecular and Clinical Medicine/Wallenberg Laboratory, Institute of MedicineUniversity of GothenburgGothenburgSweden
| | - Jan Boren
- Department of Molecular and Clinical Medicine/Wallenberg Laboratory, Institute of MedicineUniversity of GothenburgGothenburgSweden
| | - Marc Pilon
- Department of Chemistry and Molecular BiologyUniversity of GothenburgGothenburgSweden
| |
Collapse
|
39
|
Guo M, Ge M, Berberoglu MA, Zhou J, Ma L, Yang J, Dong Q, Feng Y, Wu Z, Dong Z. Dissecting Molecular and Circuit Mechanisms for Inhibition and Delayed Response of ASI Neurons during Nociceptive Stimulus. Cell Rep 2018; 25:1885-1897.e9. [PMID: 30428355 DOI: 10.1016/j.celrep.2018.10.065] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2018] [Revised: 09/05/2018] [Accepted: 10/17/2018] [Indexed: 10/27/2022] Open
Abstract
The mechanisms by which off-response neurons stay quiescent during stimulation are largely unknown. Here, we dissect underlying molecular and circuit mechanisms for the inhibition of off-response ASI neurons during nociceptive Cu2+ stimulation. ASIs are inhibited in parallel by sensory neurons ASER, ADFs, and ASHs. ASER activates RIC interneurons that release octopamine (OA) to inhibit ASIs through SER-3 and SER-6 receptors. ADFs release 5-HT that acts on the SER-1 receptor to activate RICs and subsequently inhibit ASIs. Furthermore, it is an inherent property of ASIs that only a delayed on response is evoked by Cu2+ stimulation even when all inhibitory neurons are silenced. Ectopic expression of the ion channel OCR-2, which functions synergistically with OSM-9, in the cilia of ASIs can induce an immediate on response of ASIs upon Cu2+ stimulation. Our findings elucidate the molecular and circuit mechanisms regulating fundamental properties of ASIs, including their inhibition and delayed response.
Collapse
Affiliation(s)
- Min Guo
- Bio-Medical Center, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, Hubei, 430070, China
| | - Minghai Ge
- Key Laboratory of Molecular Biophysics of Ministry of Education, Institute of Biophysics and Biochemistry, and Department of Biophysics and Molecular Physiology, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan 430074, China
| | - Michael A Berberoglu
- Bio-Medical Center, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, Hubei, 430070, China
| | - Jie Zhou
- Bio-Medical Center, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, Hubei, 430070, China
| | - Long Ma
- Bio-Medical Center, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, Hubei, 430070, China
| | - Juan Yang
- Bio-Medical Center, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, Hubei, 430070, China
| | - Qiyan Dong
- Bio-Medical Center, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, Hubei, 430070, China
| | - Yanni Feng
- Bio-Medical Center, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, Hubei, 430070, China
| | - Zhengxing Wu
- Key Laboratory of Molecular Biophysics of Ministry of Education, Institute of Biophysics and Biochemistry, and Department of Biophysics and Molecular Physiology, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan 430074, China
| | - Zhiqiang Dong
- Bio-Medical Center, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, Hubei, 430070, China.
| |
Collapse
|
40
|
Membrane Fluidity Is Regulated Cell Nonautonomously by Caenorhabditis elegans PAQR-2 and Its Mammalian Homolog AdipoR2. Genetics 2018; 210:189-201. [PMID: 29997234 PMCID: PMC6116961 DOI: 10.1534/genetics.118.301272] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2018] [Accepted: 07/09/2018] [Indexed: 01/24/2023] Open
Abstract
The properties of cell membranes are determined mostly by the types of fatty acids that they contain. Bodhicharla et al. report that a key regulator of membrane fluidity, the PAQR-2/IGLR-2 protein complex... Maintenance of membrane properties is an essential aspect of cellular homeostasis of which the regulatory mechanisms remain mostly uncharacterized. In Caenorhabditis elegans, the PAQR-2 and IGLR-2 proteins act together as a plasma membrane sensor that responds to decreased fluidity by promoting fatty acid desaturation, hence restoring membrane fluidity. Here, we used mosaic analysis for paqr-2 and iglr-2, and tissue-specific paqr-2 expression, to show that membrane homeostasis is achieved cell nonautonomously. Specifically, we found that expression of paqr-2 in the hypodermis, gonad sheath cells, or intestine is sufficient to suppress systemic paqr-2 mutant phenotypes, including tail tip morphology, membrane fluidity in intestinal cells, cold and glucose intolerance, vitellogenin transport to the germline, germ cell development, and brood size. Finally, we show that the cell nonautonomous regulation of membrane homeostasis is conserved in human cells: HEK293 cells that express AdipoR2, a homolog of paqr-2, are able to normalize membrane fluidity in distant cells where AdipoR2 has been silenced. Finally, using C. elegans mutants and small interfering RNA against Δ9 stearoyl-CoA desaturase in HEK293 cells, we show that Δ9 desaturases are essential for the cell nonautonomous maintenance of membrane fluidity. We conclude that cells are able to share membrane components even when they are not in direct contact with each other, and that this contributes to the maintenance of membrane homeostasis in C. elegans and human cells.
Collapse
|
41
|
Arey RN, Stein GM, Kaletsky R, Kauffman A, Murphy CT. Activation of G αq Signaling Enhances Memory Consolidation and Slows Cognitive Decline. Neuron 2018; 98:562-574.e5. [PMID: 29656871 DOI: 10.1016/j.neuron.2018.03.039] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2017] [Revised: 12/06/2017] [Accepted: 03/21/2018] [Indexed: 01/25/2023]
Abstract
Perhaps the most devastating decline with age is the loss of memory. Therefore, identifying mechanisms to restore memory function with age is critical. Using C. elegans associative learning and memory assays, we identified a gain-of-function Gαq signaling pathway mutant that forms a long-term (cAMP response element binding protein [CREB]-dependent) memory following one conditioned stimulus-unconditioned stimulus (CS-US) pairing, which usually requires seven CS-US pairings. Increased CREB activity in AIM interneurons reduces the threshold for memory consolidation through transcription of a set of previously identified "long-term memory" genes. Enhanced Gαq signaling in the AWC sensory neuron is both necessary and sufficient for improved memory and increased AIM CREB activity, and activation of Gαq specifically in aged animals rescues the ability to form memory. Activation of Gαq in AWC sensory neurons non-cell autonomously induces consolidation after one CS-US pairing, enabling both cognitive function maintenance with age and restoration of memory function in animals with impaired memory performance without decreased longevity.
Collapse
Affiliation(s)
- Rachel N Arey
- Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, NJ 08544, USA; Department of Molecular Biology, Princeton University, Princeton, NJ 08544, USA
| | - Geneva M Stein
- Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, NJ 08544, USA; Department of Molecular Biology, Princeton University, Princeton, NJ 08544, USA
| | - Rachel Kaletsky
- Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, NJ 08544, USA; Department of Molecular Biology, Princeton University, Princeton, NJ 08544, USA
| | - Amanda Kauffman
- Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, NJ 08544, USA; Department of Molecular Biology, Princeton University, Princeton, NJ 08544, USA
| | - Coleen T Murphy
- Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, NJ 08544, USA; Department of Molecular Biology, Princeton University, Princeton, NJ 08544, USA.
| |
Collapse
|
42
|
Split cGAL, an intersectional strategy using a split intein for refined spatiotemporal transgene control in Caenorhabditis elegans. Proc Natl Acad Sci U S A 2018; 115:3900-3905. [PMID: 29581308 DOI: 10.1073/pnas.1720063115] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Bipartite expression systems, such as the GAL4-UAS system, allow fine manipulation of gene expression and are powerful tools for interrogating gene function. Recently, we established cGAL, a GAL4-based bipartite expression system for transgene control in Caenorhabditis elegans, where a single promoter dictates the expression pattern of a cGAL driver, which then binds target upstream activation sequences to drive expression of a downstream effector gene. Here, we report a split strategy for cGAL using the split intein gp41-1 for intersectional control of transgene expression. Split inteins are protein domains that associate, self-excise, and covalently ligate their flanking peptides together. We split the DNA binding domain and transcriptional activation domain of cGAL and fused them to the N terminal of gp41-1-N-intein and the C terminal of gp41-1-C-intein, respectively. In cells where both halves of cGAL are expressed, a functional cGAL driver is reconstituted via intein-mediated protein splicing. This reconstitution allows expression of the driver to be dictated by two promoters for refined spatial control or spatiotemporal control of transgene expression. We apply the split cGAL system to genetically access the single pair of MC neurons (previously inaccessible with a single promoter), and reveal an important role of protein kinase A in rhythmic pharyngeal pumping in C. elegans Thus, the split cGAL system gives researchers a greater degree of spatiotemporal control over transgene expression, and will be a valuable genetic tool in C. elegans for dissecting gene function with finer cell-specific resolution.
Collapse
|
43
|
Ohno H, Yoshida M, Sato T, Kato J, Miyazato M, Kojima M, Ida T, Iino Y. Luqin-like RYamide peptides regulate food-evoked responses in C. elegans. eLife 2017; 6:e28877. [PMID: 28847365 PMCID: PMC5576490 DOI: 10.7554/elife.28877] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2017] [Accepted: 08/08/2017] [Indexed: 12/25/2022] Open
Abstract
Peptide signaling controls many processes involving coordinated actions of multiple organs, such as hormone-mediated appetite regulation. However, the extent to which the mode of action of peptide signaling is conserved in different animals is largely unknown, because many peptides and receptors remain orphan and many undiscovered peptides still exist. Here, we identify two novel Caenorhabditis elegans neuropeptides, LURY-1-1 and LURY-1-2, as endogenous ligands for the neuropeptide receptor-22 (NPR-22). Both peptides derive from the same precursor that is orthologous to invertebrate luqin/arginine-tyrosine-NH2 (RYamide) proneuropeptides. LURY-1 peptides are secreted from two classes of pharyngeal neurons and control food-related processes: feeding, lifespan, egg-laying, and locomotory behavior. We propose that LURY-1 peptides transmit food signals to NPR-22 expressed in feeding pacemaker neurons and a serotonergic neuron. Our results identified a critical role for luqin-like RYamides in feeding-related processes and suggested that peptide-mediated negative feedback is important for satiety regulation in C. elegans.
Collapse
Affiliation(s)
- Hayao Ohno
- Department of Biological SciencesGraduate School of Science, The University of TokyoTokyoJapan
| | - Morikatsu Yoshida
- Department of BiochemistryNational Cerebral and Cardiovascular Center Research InstituteOsakaJapan
| | - Takahiro Sato
- Molecular GeneticsInstitute of Life Sciences, Kurume UniversityFukuokaJapan
| | - Johji Kato
- Department of Bioactive PeptidesFrontier Science Research Center, University of MiyazakiMiyazakiJapan
| | - Mikiya Miyazato
- Department of BiochemistryNational Cerebral and Cardiovascular Center Research InstituteOsakaJapan
| | - Masayasu Kojima
- Molecular GeneticsInstitute of Life Sciences, Kurume UniversityFukuokaJapan
| | - Takanori Ida
- Department of Bioactive PeptidesFrontier Science Research Center, University of MiyazakiMiyazakiJapan
- Center for Animal Disease ControlUniversity of MiyazakiMiyazakiJapan
| | - Yuichi Iino
- Department of Biological SciencesGraduate School of Science, The University of TokyoTokyoJapan
| |
Collapse
|
44
|
Muñoz-Jiménez C, Ayuso C, Dobrzynska A, Torres-Mendéz A, Ruiz PDLC, Askjaer P. An Efficient FLP-Based Toolkit for Spatiotemporal Control of Gene Expression in Caenorhabditis elegans. Genetics 2017; 206:1763-1778. [PMID: 28646043 PMCID: PMC5560786 DOI: 10.1534/genetics.117.201012] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2017] [Accepted: 06/19/2017] [Indexed: 02/07/2023] Open
Abstract
Site-specific recombinases are potent tools to regulate gene expression. In particular, the Cre (cyclization recombination) and FLP (flipase) enzymes are widely used to either activate or inactivate genes in a precise spatiotemporal manner. Both recombinases work efficiently in the popular model organism Caenorhabditis elegans, but their use in this nematode is still only sporadic. To increase the utility of the FLP system in C. elegans, we have generated a series of single-copy transgenic strains that stably express an optimized version of FLP in specific tissues or by heat induction. We show that recombination efficiencies reach 100% in several cell types, such as muscles, intestine, and serotonin-producing neurons. Moreover, we demonstrate that most promoters drive recombination exclusively in the expected tissues. As examples of the potentials of the FLP lines, we describe novel tools for induced cell ablation by expression of the PEEL-1 toxin and a versatile FLP-out cassette for generation of GFP-tagged conditional knockout alleles. Together with other recombinase-based reagents created by the C. elegans community, this toolkit increases the possibilities for detailed analyses of specific biological processes at developmental stages inside intact animals.
Collapse
Affiliation(s)
- Celia Muñoz-Jiménez
- Andalusian Center for Developmental Biology (CABD), CSIC/JA/Universidad Pablo de Olavide, 41013 Seville, Spain
| | - Cristina Ayuso
- Andalusian Center for Developmental Biology (CABD), CSIC/JA/Universidad Pablo de Olavide, 41013 Seville, Spain
| | - Agnieszka Dobrzynska
- Andalusian Center for Developmental Biology (CABD), CSIC/JA/Universidad Pablo de Olavide, 41013 Seville, Spain
| | - Antonio Torres-Mendéz
- Andalusian Center for Developmental Biology (CABD), CSIC/JA/Universidad Pablo de Olavide, 41013 Seville, Spain
| | - Patricia de la Cruz Ruiz
- Andalusian Center for Developmental Biology (CABD), CSIC/JA/Universidad Pablo de Olavide, 41013 Seville, Spain
| | - Peter Askjaer
- Andalusian Center for Developmental Biology (CABD), CSIC/JA/Universidad Pablo de Olavide, 41013 Seville, Spain
| |
Collapse
|
45
|
The NCA-1 and NCA-2 Ion Channels Function Downstream of G q and Rho To Regulate Locomotion in Caenorhabditis elegans. Genetics 2017; 206:265-282. [PMID: 28325749 DOI: 10.1534/genetics.116.198820] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2016] [Accepted: 03/15/2017] [Indexed: 02/07/2023] Open
Abstract
The heterotrimeric G protein Gq positively regulates neuronal activity and synaptic transmission. Previously, the Rho guanine nucleotide exchange factor Trio was identified as a direct effector of Gq that acts in parallel to the canonical Gq effector phospholipase C. Here, we examine how Trio and Rho act to stimulate neuronal activity downstream of Gq in the nematode Caenorhabditis elegans Through two forward genetic screens, we identify the cation channels NCA-1 and NCA-2, orthologs of mammalian NALCN, as downstream targets of the Gq-Rho pathway. By performing genetic epistasis analysis using dominant activating mutations and recessive loss-of-function mutations in the members of this pathway, we show that NCA-1 and NCA-2 act downstream of Gq in a linear pathway. Through cell-specific rescue experiments, we show that function of these channels in head acetylcholine neurons is sufficient for normal locomotion in C. elegans Our results suggest that NCA-1 and NCA-2 are physiologically relevant targets of neuronal Gq-Rho signaling in C. elegans.
Collapse
|
46
|
cGAL, a temperature-robust GAL4-UAS system for Caenorhabditis elegans. Nat Methods 2016; 14:145-148. [PMID: 27992408 PMCID: PMC5693259 DOI: 10.1038/nmeth.4109] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2016] [Accepted: 11/18/2016] [Indexed: 01/27/2023]
Abstract
The GAL4-UAS system is a powerful tool for manipulating gene expression, but its application in Caenorhabditis elegans has not been described. Here we systematically optimize the system's three main components to develop a temperature-optimized GAL4-UAS system (cGAL) that robustly controls gene expression in C. elegans from 15 to 25 °C. We demonstrate this system's utility in transcriptional reporter analysis, site-of-action experiments and exogenous transgene expression; and we provide a basic driver and effector toolkit.
Collapse
|
47
|
Sagi D, Rak R, Gingold H, Adir I, Maayan G, Dahan O, Broday L, Pilpel Y, Rechavi O. Tissue- and Time-Specific Expression of Otherwise Identical tRNA Genes. PLoS Genet 2016; 12:e1006264. [PMID: 27560950 PMCID: PMC4999229 DOI: 10.1371/journal.pgen.1006264] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2016] [Accepted: 07/27/2016] [Indexed: 11/18/2022] Open
Abstract
Codon usage bias affects protein translation because tRNAs that recognize synonymous codons differ in their abundance. Although the current dogma states that tRNA expression is exclusively regulated by intrinsic control elements (A- and B-box sequences), we revealed, using a reporter that monitors the levels of individual tRNA genes in Caenorhabditis elegans, that eight tryptophan tRNA genes, 100% identical in sequence, are expressed in different tissues and change their expression dynamically. Furthermore, the expression levels of the sup-7 tRNA gene at day 6 were found to predict the animal's lifespan. We discovered that the expression of tRNAs that reside within introns of protein-coding genes is affected by the host gene's promoter. Pairing between specific Pol II genes and the tRNAs that are contained in their introns is most likely adaptive, since a genome-wide analysis revealed that the presence of specific intronic tRNAs within specific orthologous genes is conserved across Caenorhabditis species.
Collapse
Affiliation(s)
- Dror Sagi
- Department of Neurobiology, Wise Faculty of Life Sciences and Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, Israel
| | - Roni Rak
- Department of Neurobiology, Wise Faculty of Life Sciences and Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, Israel
| | - Hila Gingold
- Department of Molecular Genetics, The Weizmann Institute of Science, Rehovot, Israel
| | - Idan Adir
- Department of Neurobiology, Wise Faculty of Life Sciences and Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, Israel
| | - Gadi Maayan
- Department of Neurobiology, Wise Faculty of Life Sciences and Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, Israel
| | - Orna Dahan
- Department of Molecular Genetics, The Weizmann Institute of Science, Rehovot, Israel
| | - Limor Broday
- Department of Cell and Developmental Biology, Sackler School of Medicine, Tel Aviv University, Tel-Aviv, Israel
| | - Yitzhak Pilpel
- Department of Molecular Genetics, The Weizmann Institute of Science, Rehovot, Israel
| | - Oded Rechavi
- Department of Neurobiology, Wise Faculty of Life Sciences and Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, Israel
| |
Collapse
|
48
|
Peña S, Sherman T, Brookes PS, Nehrke K. The Mitochondrial Unfolded Protein Response Protects against Anoxia in Caenorhabditis elegans. PLoS One 2016; 11:e0159989. [PMID: 27459203 PMCID: PMC4961406 DOI: 10.1371/journal.pone.0159989] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2016] [Accepted: 06/27/2016] [Indexed: 02/06/2023] Open
Abstract
The mitochondrial unfolded protein response (UPRmt) is a surveillance pathway that defends proteostasis in the “powerhouse” of the cell. Activation of the UPRmt protects against stresses imposed by reactive oxygen species, respiratory chain deficits, and pathologic bacteria. Consistent with the UPRmt’s role in adaption, we found that either its pharmacological or genetic activation by ethidium bromide (EtBr) or RNAi of the mitochondrial AAA-protease spg-7 was sufficient to reduce death in an anoxia-based Caenorhabditis elegans model of ischemia-reperfusion injury. The UPRmt-specific transcription factor atfs-1 was necessary for protection and atfs-1 gain-of-function (gf) mutants were endogenously protected from both death and dysfunction. Neurons exhibited less axonal degeneration following non-lethal anoxia-reperfusion (A-R) when the UPRmt was pre-activated, and consistent with the concept of mitochondrial stress leading to cell non-autonomous (ie. “remote”) effects, we found that restricted activation of the UPRmt in neurons decreased A-R death. However, expression of the atfs-1(gf) mutant in neurons, which resulted in a robust activation of a neuronal UPRmt, did not upregulate the UPRmt in distal tissues, nor did it protect the worms from A-R toxicity. These findings suggest that remote signaling requires additional component(s) acting downstream of de facto mitochondrial stress.
Collapse
Affiliation(s)
- Salvador Peña
- Department of Pathology and Laboratory Medicine, University of Rochester Medical Center, Rochester, New York, United States of America
| | - Teresa Sherman
- Department of Medicine, University of Rochester Medical Center, Rochester, New York, United States of America
| | - Paul S. Brookes
- Department of Anesthesiology, University of Rochester Medical Center, Rochester, New York, United States of America
- Department of Pharmacology and Physiology, University of Rochester Medical Center, Rochester, New York, United States of America
| | - Keith Nehrke
- Department of Medicine, University of Rochester Medical Center, Rochester, New York, United States of America
- Department of Pharmacology and Physiology, University of Rochester Medical Center, Rochester, New York, United States of America
- * E-mail:
| |
Collapse
|
49
|
Fang-Yen C, Alkema MJ, Samuel ADT. Illuminating neural circuits and behaviour in Caenorhabditis elegans with optogenetics. Philos Trans R Soc Lond B Biol Sci 2016; 370:20140212. [PMID: 26240427 DOI: 10.1098/rstb.2014.0212] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
The development of optogenetics, a family of methods for using light to control neural activity via light-sensitive proteins, has provided a powerful new set of tools for neurobiology. These techniques have been particularly fruitful for dissecting neural circuits and behaviour in the compact and transparent roundworm Caenorhabditis elegans. Researchers have used optogenetic reagents to manipulate numerous excitable cell types in the worm, from sensory neurons, to interneurons, to motor neurons and muscles. Here, we show how optogenetics applied to this transparent roundworm has contributed to our understanding of neural circuits.
Collapse
Affiliation(s)
- Christopher Fang-Yen
- Department of Bioengineering, School of Engineering and Applied Science, University of Pennsylvania, Philadelphia, PA 19104, USA Department of Neuroscience, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Mark J Alkema
- Department of Neurobiology, University of Massachusetts Medical School, Worcester, MA 01655, USA
| | - Aravinthan D T Samuel
- Department of Physics and Center for Brain Science, Harvard University, Cambridge, MA 02138, USA
| |
Collapse
|
50
|
Schwartz ML, Jorgensen EM. SapTrap, a Toolkit for High-Throughput CRISPR/Cas9 Gene Modification in Caenorhabditis elegans. Genetics 2016; 202:1277-88. [PMID: 26837755 PMCID: PMC4905529 DOI: 10.1534/genetics.115.184275] [Citation(s) in RCA: 108] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2015] [Accepted: 01/20/2016] [Indexed: 01/16/2023] Open
Abstract
In principle, clustered regularly interspaced short palindromic repeats (CRISPR)/Cas9 allows genetic tags to be inserted at any locus. However, throughput is limited by the laborious construction of repair templates and guide RNA constructs and by the identification of modified strains. We have developed a reagent toolkit and plasmid assembly pipeline, called "SapTrap," that streamlines the production of targeting vectors for tag insertion, as well as the selection of modified Caenorhabditis elegans strains. SapTrap is a high-efficiency modular plasmid assembly pipeline that produces single plasmid targeting vectors, each of which encodes both a guide RNA transcript and a repair template for a particular tagging event. The plasmid is generated in a single tube by cutting modular components with the restriction enzyme SapI, which are then "trapped" in a fixed order by ligation to generate the targeting vector. A library of donor plasmids supplies a variety of protein tags, a selectable marker, and regulatory sequences that allow cell-specific tagging at either the N or the C termini. All site-specific sequences, such as guide RNA targeting sequences and homology arms, are supplied as annealed synthetic oligonucleotides, eliminating the need for PCR or molecular cloning during plasmid assembly. Each tag includes an embedded Cbr-unc-119 selectable marker that is positioned to allow concurrent expression of both the tag and the marker. We demonstrate that SapTrap targeting vectors direct insertion of 3- to 4-kb tags at six different loci in 10-37% of injected animals. Thus SapTrap vectors introduce the possibility for high-throughput generation of CRISPR/Cas9 genome modifications.
Collapse
Affiliation(s)
- Matthew L Schwartz
- Department of Biology, University of Utah, Salt Lake City, Utah 84112-0840 Howard Hughes Medical Institute, University of Utah, Salt Lake City, Utah 84112-0840
| | - Erik M Jorgensen
- Department of Biology, University of Utah, Salt Lake City, Utah 84112-0840 Howard Hughes Medical Institute, University of Utah, Salt Lake City, Utah 84112-0840
| |
Collapse
|