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Sharma G, Zee PC, Zea L, Curtis PD. Whole genome-scale assessment of gene fitness of Novosphingobium aromaticavorans during spaceflight. BMC Genomics 2023; 24:782. [PMID: 38102595 PMCID: PMC10725011 DOI: 10.1186/s12864-023-09799-z] [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: 08/11/2023] [Accepted: 11/10/2023] [Indexed: 12/17/2023] Open
Abstract
In microgravity, bacteria undergo intriguing physiological adaptations. There have been few attempts to assess global bacterial physiological responses to microgravity, with most studies only focusing on a handful of individual systems. This study assessed the fitness of each gene in the genome of the aromatic compound-degrading Alphaproteobacterium Novosphingobium aromaticavorans during growth in spaceflight. This was accomplished using Comparative TnSeq, which involves culturing the same saturating transposon mutagenized library under two different conditions. To assess gene fitness, a novel comparative TnSeq analytical tool was developed, named TnDivA, that is particularly useful in leveraging biological replicates. In this approach, transposon diversity is represented numerically using a modified Shannon diversity index, which was then converted into effective transposon density. This transformation accounts for variability in read distribution between samples, such as cases where reads were dominated by only a few transposon inserts. Effective density values were analyzed using multiple statistical methods, including log2-fold change, least-squares regression analysis, and Welch's t-test. The results obtained across applied statistical methods show a difference in the number of significant genes identified. However, the functional categories of genes important to growth in microgravity showed similar patterns. Lipid metabolism and transport, energy production, transcription, translation, and secondary metabolite biosynthesis and transport were shown to have high fitness during spaceflight. This suggests that core metabolic processes, including lipid and secondary metabolism, play an important role adapting to stress and promoting growth in microgravity.
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Affiliation(s)
- Gayatri Sharma
- Department of Biology, University of Mississippi, 402 Shoemaker Hall, University, MS, 38677, USA
| | - Peter C Zee
- Department of Biology, University of Mississippi, 402 Shoemaker Hall, University, MS, 38677, USA
| | - Luis Zea
- Aerospace Engineering Sciences, University of Colorado Boulder, Boulder, CO, 80303, USA
| | - Patrick D Curtis
- Department of Biology, University of Mississippi, 402 Shoemaker Hall, University, MS, 38677, USA.
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2
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Xu C, Xu J, Tang HW, Ericsson M, Weng JH, DiRusso J, Hu Y, Ma W, Asara JM, Perrimon N. A phosphate-sensing organelle regulates phosphate and tissue homeostasis. Nature 2023; 617:798-806. [PMID: 37138087 PMCID: PMC10443203 DOI: 10.1038/s41586-023-06039-y] [Citation(s) in RCA: 12] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2020] [Accepted: 03/31/2023] [Indexed: 05/05/2023]
Abstract
Inorganic phosphate (Pi) is one of the essential molecules for life. However, little is known about intracellular Pi metabolism and signalling in animal tissues1. Following the observation that chronic Pi starvation causes hyperproliferation in the digestive epithelium of Drosophila melanogaster, we determined that Pi starvation triggers the downregulation of the Pi transporter PXo. In line with Pi starvation, PXo deficiency caused midgut hyperproliferation. Interestingly, immunostaining and ultrastructural analyses showed that PXo specifically marks non-canonical multilamellar organelles (PXo bodies). Further, by Pi imaging with a Förster resonance energy transfer (FRET)-based Pi sensor2, we found that PXo restricts cytosolic Pi levels. PXo bodies require PXo for biogenesis and undergo degradation following Pi starvation. Proteomic and lipidomic characterization of PXo bodies unveiled their distinct feature as an intracellular Pi reserve. Therefore, Pi starvation triggers PXo downregulation and PXo body degradation as a compensatory mechanism to increase cytosolic Pi. Finally, we identified connector of kinase to AP-1 (Cka), a component of the STRIPAK complex and JNK signalling3, as the mediator of PXo knockdown- or Pi starvation-induced hyperproliferation. Altogether, our study uncovers PXo bodies as a critical regulator of cytosolic Pi levels and identifies a Pi-dependent PXo-Cka-JNK signalling cascade controlling tissue homeostasis.
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Affiliation(s)
- Chiwei Xu
- Department of Genetics, Blavatnik Institute, Harvard Medical School, Boston, MA, USA.
- Robin Chemers Neustein Laboratory of Mammalian Development and Cell Biology, The Rockefeller University, New York, NY, USA.
| | - Jun Xu
- Department of Genetics, Blavatnik Institute, Harvard Medical School, Boston, MA, USA
- CAS Key Laboratory of Insect Developmental and Evolutionary Biology, CAS Center for Excellence in Molecular Plant Sciences, Chinese Academy of Sciences, Shanghai, China
| | - Hong-Wen Tang
- Department of Genetics, Blavatnik Institute, Harvard Medical School, Boston, MA, USA
- Program in Cancer and Stem Cell Biology, Duke-NUS Medical School, Singapore, Singapore
| | - Maria Ericsson
- Department of Cell Biology, Electron Microscopy Facility, Blavatnik Institute, Harvard Medical School, Boston, MA, USA
| | - Jui-Hsia Weng
- Institute of Biological Chemistry, Academia Sinica, Taipei, Taiwan
| | - Jonathan DiRusso
- Department of Genetics, Blavatnik Institute, Harvard Medical School, Boston, MA, USA
| | - Yanhui Hu
- Department of Genetics, Blavatnik Institute, Harvard Medical School, Boston, MA, USA
| | - Wenzhe Ma
- Department of Systems Biology, Harvard Medical School, Boston, MA, USA
| | - John M Asara
- Department of Medicine, Blavatnik Institute, Harvard Medical School, Boston, MA, USA
- Department of Signal Transduction, Beth Israel Deaconess Medical Center, Boston, MA, USA
| | - Norbert Perrimon
- Department of Genetics, Blavatnik Institute, Harvard Medical School, Boston, MA, USA.
- Howard Hughes Medical Institute, Harvard Medical School, Boston, MA, USA.
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3
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Xia B, Viswanatha R, Hu Y, Mohr SE, Perrimon N. Pooled genome-wide CRISPR activation screening for rapamycin resistance genes in Drosophila cells. eLife 2023; 12:e85542. [PMID: 37078570 PMCID: PMC10118385 DOI: 10.7554/elife.85542] [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: 12/13/2022] [Accepted: 04/09/2023] [Indexed: 04/21/2023] Open
Abstract
Loss-of-function and gain-of-function genetic perturbations provide valuable insights into gene function. In Drosophila cells, while genome-wide loss-of-function screens have been extensively used to reveal mechanisms of a variety of biological processes, approaches for performing genome-wide gain-of-function screens are still lacking. Here, we describe a pooled CRISPR activation (CRISPRa) screening platform in Drosophila cells and apply this method to both focused and genome-wide screens to identify rapamycin resistance genes. The screens identified three genes as novel rapamycin resistance genes: a member of the SLC16 family of monocarboxylate transporters (CG8468), a member of the lipocalin protein family (CG5399), and a zinc finger C2H2 transcription factor (CG9932). Mechanistically, we demonstrate that CG5399 overexpression activates the RTK-Akt-mTOR signaling pathway and that activation of insulin receptor (InR) by CG5399 requires cholesterol and clathrin-coated pits at the cell membrane. This study establishes a novel platform for functional genetic studies in Drosophila cells.
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Affiliation(s)
- Baolong Xia
- Department of Genetics, Blavatnik Institute, Harvard Medical SchoolBostonUnited States
| | - Raghuvir Viswanatha
- Department of Genetics, Blavatnik Institute, Harvard Medical SchoolBostonUnited States
| | - Yanhui Hu
- Department of Genetics, Blavatnik Institute, Harvard Medical SchoolBostonUnited States
- Drosophila RNAi Screening Center, Harvard Medical SchoolBostonUnited States
| | - Stephanie E Mohr
- Department of Genetics, Blavatnik Institute, Harvard Medical SchoolBostonUnited States
- Drosophila RNAi Screening Center, Harvard Medical SchoolBostonUnited States
| | - Norbert Perrimon
- Department of Genetics, Blavatnik Institute, Harvard Medical SchoolBostonUnited States
- Drosophila RNAi Screening Center, Harvard Medical SchoolBostonUnited States
- Howard Hughes Medical InstituteBostonUnited States
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4
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Han S, Dias GB, Basting PJ, Viswanatha R, Perrimon N, Bergman C. Local assembly of long reads enables phylogenomics of transposable elements in a polyploid cell line. Nucleic Acids Res 2022; 50:e124. [PMID: 36156149 PMCID: PMC9757076 DOI: 10.1093/nar/gkac794] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2022] [Revised: 07/21/2022] [Accepted: 09/16/2022] [Indexed: 12/24/2022] Open
Abstract
Animal cell lines often undergo extreme genome restructuring events, including polyploidy and segmental aneuploidy that can impede de novo whole-genome assembly (WGA). In some species like Drosophila, cell lines also exhibit massive proliferation of transposable elements (TEs). To better understand the role of transposition during animal cell culture, we sequenced the genome of the tetraploid Drosophila S2R+ cell line using long-read and linked-read technologies. WGAs for S2R+ were highly fragmented and generated variable estimates of TE content across sequencing and assembly technologies. We therefore developed a novel WGA-independent bioinformatics method called TELR that identifies, locally assembles, and estimates allele frequency of TEs from long-read sequence data (https://github.com/bergmanlab/telr). Application of TELR to a ∼130x PacBio dataset for S2R+ revealed many haplotype-specific TE insertions that arose by transposition after initial cell line establishment and subsequent tetraploidization. Local assemblies from TELR also allowed phylogenetic analysis of paralogous TEs, which revealed that proliferation of TE families in vitro can be driven by single or multiple source lineages. Our work provides a model for the analysis of TEs in complex heterozygous or polyploid genomes that are recalcitrant to WGA and yields new insights into the mechanisms of genome evolution in animal cell culture.
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Affiliation(s)
| | | | - Preston J Basting
- Institute of Bioinformatics, University of Georgia, 120 E. Green St., Athens, GA, USA
| | - Raghuvir Viswanatha
- Department of Genetics, Harvard Medical School, 77 Avenue Louis Pasteur, Boston, MA, USA
| | - Norbert Perrimon
- Department of Genetics, Harvard Medical School, 77 Avenue Louis Pasteur, Boston, MA, USA,Howard Hughes Medical Institute, Boston, MA, USA
| | - Casey M Bergman
- To whom correspondence should be addressed. Tel: +1 706 542 1764; Fax: +1 706 542 3910;
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5
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Gu X, Jouandin P, Lalgudi PV, Binari R, Valenstein ML, Reid MA, Allen AE, Kamitaki N, Locasale JW, Perrimon N, Sabatini DM. Sestrin mediates detection of and adaptation to low-leucine diets in Drosophila. Nature 2022; 608:209-216. [PMID: 35859173 PMCID: PMC10112710 DOI: 10.1038/s41586-022-04960-2] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2020] [Accepted: 06/09/2022] [Indexed: 12/28/2022]
Abstract
Mechanistic target of rapamycin complex 1 (mTORC1) regulates cell growth and metabolism in response to multiple nutrients, including the essential amino acid leucine1. Recent work in cultured mammalian cells established the Sestrins as leucine-binding proteins that inhibit mTORC1 signalling during leucine deprivation2,3, but their role in the organismal response to dietary leucine remains elusive. Here we find that Sestrin-null flies (Sesn-/-) fail to inhibit mTORC1 or activate autophagy after acute leucine starvation and have impaired development and a shortened lifespan on a low-leucine diet. Knock-in flies expressing a leucine-binding-deficient Sestrin mutant (SesnL431E) have reduced, leucine-insensitive mTORC1 activity. Notably, we find that flies can discriminate between food with or without leucine, and preferentially feed and lay progeny on leucine-containing food. This preference depends on Sestrin and its capacity to bind leucine. Leucine regulates mTORC1 activity in glial cells, and knockdown of Sesn in these cells reduces the ability of flies to detect leucine-free food. Thus, nutrient sensing by mTORC1 is necessary for flies not only to adapt to, but also to detect, a diet deficient in an essential nutrient.
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Affiliation(s)
- Xin Gu
- Whitehead Institute for Biomedical Research, Cambridge, MA, USA.
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA, USA.
| | - Patrick Jouandin
- Department of Genetics, Blavatnik Institute, Harvard Medical School, Boston, MA, USA.
- Howard Hughes Medical Institute, Harvard Medical School, Boston, MA, USA.
| | - Pranav V Lalgudi
- Whitehead Institute for Biomedical Research, Cambridge, MA, USA
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Rich Binari
- Department of Genetics, Blavatnik Institute, Harvard Medical School, Boston, MA, USA
- Howard Hughes Medical Institute, Harvard Medical School, Boston, MA, USA
| | - Max L Valenstein
- Whitehead Institute for Biomedical Research, Cambridge, MA, USA
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Michael A Reid
- Department of Pharmacology and Cancer Biology, Duke University School of Medicine, Durham, NC, USA
| | - Annamarie E Allen
- Department of Pharmacology and Cancer Biology, Duke University School of Medicine, Durham, NC, USA
| | - Nolan Kamitaki
- Department of Genetics, Blavatnik Institute, Harvard Medical School, Boston, MA, USA
- Broad Institute of Harvard and Massachusetts Institute of Technology, Cambridge, MA, USA
- Department of Biomedical Informatics, Harvard Medical School, Boston, MA, USA
| | - Jason W Locasale
- Department of Pharmacology and Cancer Biology, Duke University School of Medicine, Durham, NC, USA
| | - Norbert Perrimon
- Department of Genetics, Blavatnik Institute, Harvard Medical School, Boston, MA, USA.
- Howard Hughes Medical Institute, Harvard Medical School, Boston, MA, USA.
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6
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Han S, Dias GB, Basting PJ, Nelson MG, Patel S, Marzo M, Bergman CM. Ongoing transposition in cell culture reveals the phylogeny of diverse Drosophila S2 sublines. Genetics 2022; 221:iyac077. [PMID: 35536183 PMCID: PMC9252272 DOI: 10.1093/genetics/iyac077] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2022] [Accepted: 04/28/2022] [Indexed: 11/13/2022] Open
Abstract
Cultured cells are widely used in molecular biology despite poor understanding of how cell line genomes change in vitro over time. Previous work has shown that Drosophila cultured cells have a higher transposable element content than whole flies, but whether this increase in transposable element content resulted from an initial burst of transposition during cell line establishment or ongoing transposition in cell culture remains unclear. Here, we sequenced the genomes of 25 sublines of Drosophila S2 cells and show that transposable element insertions provide abundant markers for the phylogenetic reconstruction of diverse sublines in a model animal cell culture system. DNA copy number evolution across S2 sublines revealed dramatically different patterns of genome organization that support the overall evolutionary history reconstructed using transposable element insertions. Analysis of transposable element insertion site occupancy and ancestral states support a model of ongoing transposition dominated by episodic activity of a small number of retrotransposon families. Our work demonstrates that substantial genome evolution occurs during long-term Drosophila cell culture, which may impact the reproducibility of experiments that do not control for subline identity.
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Affiliation(s)
- Shunhua Han
- Institute of Bioinformatics, University of Georgia, Athens, GA 30602, USA
| | - Guilherme B Dias
- Institute of Bioinformatics, University of Georgia, Athens, GA 30602, USA
- Department of Genetics, University of Georgia, Athens, GA 30602, USA
| | - Preston J Basting
- Institute of Bioinformatics, University of Georgia, Athens, GA 30602, USA
| | - Michael G Nelson
- Faculty of Life Sciences, University of Manchester, Manchester M13 9PT, UK
| | - Sanjai Patel
- Faculty of Life Sciences, University of Manchester, Manchester M13 9PT, UK
| | - Mar Marzo
- Faculty of Life Sciences, University of Manchester, Manchester M13 9PT, UK
| | - Casey M Bergman
- Institute of Bioinformatics, University of Georgia, Athens, GA 30602, USA
- Department of Genetics, University of Georgia, Athens, GA 30602, USA
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