1
|
Wang B, Zhou X, Kettenbach AN, Mitchell HD, Markillie LM, Loros JJ, Dunlap JC. A crucial role for dynamic expression of components encoding the negative arm of the circadian clock. Nat Commun 2023; 14:3371. [PMID: 37291101 PMCID: PMC10250352 DOI: 10.1038/s41467-023-38817-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2022] [Accepted: 05/17/2023] [Indexed: 06/10/2023] Open
Abstract
In the Neurospora circadian system, the White Collar Complex (WCC) drives expression of the principal circadian negative arm component frequency (frq). FRQ interacts with FRH (FRQ-interacting RNA helicase) and CKI, forming a stable complex that represses its own expression by inhibiting WCC. In this study, a genetic screen identified a gene, designated as brd-8, that encodes a conserved auxiliary subunit of the NuA4 histone acetylation complex. Loss of brd-8 reduces H4 acetylation and RNA polymerase (Pol) II occupancy at frq and other known circadian genes, and leads to a long circadian period, delayed phase, and defective overt circadian output at some temperatures. In addition to strongly associating with the NuA4 histone acetyltransferase complex, BRD-8 is also found complexed with the transcription elongation regulator BYE-1. Expression of brd-8, bye-1, histone h2a.z, and several NuA4 subunits is controlled by the circadian clock, indicating that the molecular clock both regulates the basic chromatin status and is regulated by changes in chromatin. Taken together, our data identify auxiliary elements of the fungal NuA4 complex having homology to mammalian components, which along with conventional NuA4 subunits, are required for timely and dynamic frq expression and thereby a normal and persistent circadian rhythm.
Collapse
Affiliation(s)
- Bin Wang
- Department of Molecular and Systems Biology, Geisel School of Medicine at Dartmouth, Hanover, NH, 03755, USA.
| | - Xiaoying Zhou
- Department of Molecular and Systems Biology, Geisel School of Medicine at Dartmouth, Hanover, NH, 03755, USA
| | - Arminja N Kettenbach
- Department of Biochemistry and Cell Biology, Geisel School of Medicine at Dartmouth, Hanover, NH, 03755, USA
| | - Hugh D Mitchell
- Biological Sciences Divisions, Pacific Northwest National Laboratory, Richland, WA, 99352, USA
- Earth and Biological Sciences Directorate, Pacific Northwest National Laboratory, Richland, WA, 99352, USA
| | - Lye Meng Markillie
- Biological Sciences Divisions, Pacific Northwest National Laboratory, Richland, WA, 99352, USA
- Earth and Biological Sciences Directorate, Pacific Northwest National Laboratory, Richland, WA, 99352, USA
| | - Jennifer J Loros
- Department of Molecular and Systems Biology, Geisel School of Medicine at Dartmouth, Hanover, NH, 03755, USA
- Department of Biochemistry and Cell Biology, Geisel School of Medicine at Dartmouth, Hanover, NH, 03755, USA
| | - Jay C Dunlap
- Department of Molecular and Systems Biology, Geisel School of Medicine at Dartmouth, Hanover, NH, 03755, USA.
| |
Collapse
|
2
|
Wang B, Zhou X, Kettenbach AN, Mitchell HD, Markillie LM, Loros JJ, Dunlap JC. A crucial role for dynamic expression of components encoding the negative arm of the circadian clock. bioRxiv 2023:2023.04.24.538162. [PMID: 37162945 PMCID: PMC10168201 DOI: 10.1101/2023.04.24.538162] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
In the Neurospora circadian system, the White Collar Complex (WCC) drives expression of the principal circadian negative arm component frequency ( frq ). FRQ interacts with FRH (FRQ-interacting helicase) and CK-1 forming a stable complex that represses its own expression by inhibiting WCC. In this study, a genetic screen identified a gene, designated as brd-8 , that encodes a conserved auxiliary subunit of the NuA4 histone acetylation complex. Loss of brd-8 reduces H4 acetylation and RNA polymerase (Pol) II occupancy at frq and other known circadian genes, and leads to a long circadian period, delayed phase, and defective overt circadian output at some temperatures. In addition to strongly associating with the NuA4 histone acetyltransferase complex, BRD-8 is also found complexed with the transcription elongation regulator BYE-1. Expression of brd-8, bye-1, histone hH2Az , and several NuA4 subunits is controlled by the circadian clock, indicating that the molecular clock both regulates the basic chromatin status and is regulated by changes in chromatin. Taken together, our data identify new auxiliary elements of the fungal NuA4 complex having homology to mammalian components, which along with conventional NuA4 subunits, are required for timely and dynamic frq expression and thereby a normal and persistent circadian rhythm.
Collapse
|
3
|
Kelliher CM, Stevenson EL, Loros JJ, Dunlap JC. Nutritional compensation of the circadian clock is a conserved process influenced by gene expression regulation and mRNA stability. PLoS Biol 2023; 21:e3001961. [PMID: 36603054 PMCID: PMC9848017 DOI: 10.1371/journal.pbio.3001961] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2022] [Revised: 01/18/2023] [Accepted: 12/15/2022] [Indexed: 01/06/2023] Open
Abstract
Compensation is a defining principle of a true circadian clock, where its approximately 24-hour period length is relatively unchanged across environmental conditions. Known compensation effectors directly regulate core clock factors to buffer the oscillator's period length from variables in the environment. Temperature Compensation mechanisms have been experimentally addressed across circadian model systems, but much less is known about the related process of Nutritional Compensation, where circadian period length is maintained across physiologically relevant nutrient levels. Using the filamentous fungus Neurospora crassa, we performed a genetic screen under glucose and amino acid starvation conditions to identify new regulators of Nutritional Compensation. Our screen uncovered 16 novel mutants, and together with 4 mutants characterized in prior work, a model emerges where Nutritional Compensation of the fungal clock is achieved at the levels of transcription, chromatin regulation, and mRNA stability. However, eukaryotic circadian Nutritional Compensation is completely unstudied outside of Neurospora. To test for conservation in cultured human cells, we selected top hits from our fungal genetic screen, performed siRNA knockdown experiments of the mammalian orthologs, and characterized the cell lines with respect to compensation. We find that the wild-type mammalian clock is also compensated across a large range of external glucose concentrations, as observed in Neurospora, and that knocking down the mammalian orthologs of the Neurospora compensation-associated genes CPSF6 or SETD2 in human cells also results in nutrient-dependent period length changes. We conclude that, like Temperature Compensation, Nutritional Compensation is a conserved circadian process in fungal and mammalian clocks and that it may share common molecular determinants.
Collapse
Affiliation(s)
- Christina M. Kelliher
- Department of Molecular & Systems Biology, Geisel School of Medicine at Dartmouth, Hanover, New Hampshire, United States of America
- Department of Biology, University of Massachusetts Boston, Boston, Massachusetts, United States of America
| | - Elizabeth-Lauren Stevenson
- Department of Molecular & Systems Biology, Geisel School of Medicine at Dartmouth, Hanover, New Hampshire, United States of America
| | - Jennifer J. Loros
- Department of Biochemistry & Cell Biology, Geisel School of Medicine at Dartmouth, Hanover, New Hampshire, United States of America
| | - Jay C. Dunlap
- Department of Molecular & Systems Biology, Geisel School of Medicine at Dartmouth, Hanover, New Hampshire, United States of America
| |
Collapse
|
4
|
Wang Z, Bartholomai BM, Loros JJ, Dunlap JC. Optimized fluorescent proteins for 4-color and photoconvertible live-cell imaging in Neurospora crassa. Fungal Genet Biol 2023; 164:103763. [PMID: 36481248 PMCID: PMC10501358 DOI: 10.1016/j.fgb.2022.103763] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2022] [Revised: 11/27/2022] [Accepted: 11/30/2022] [Indexed: 12/12/2022]
Abstract
Fungal cells are quite unique among life in their organization and structure, and yet implementation of many tools recently developed for fluorescence imaging in animal systems and yeast has been slow in filamentous fungi. Here we present analysis of properties of fluorescent proteins in Neurospora crassa as well as describing genetic tools for the expression of these proteins that may be useful beyond cell biology applications. The brightness and photostability of ten different fluorescent protein tags were compared in a well-controlled system; six different promoters are described for the assessment of the fluorescent proteins and varying levels of expression, as well as a customizable bidirectional promoter system. We present an array of fluorescent proteins suitable for use across the visible light spectrum to allow for 4-color imaging, in addition to a photoconvertible fluorescent protein that enables a change in the color of a small subset of proteins in the cell. These tools build on the rich history of cell biology research in filamentous fungi and provide new tools to help expand research capabilities.
Collapse
Affiliation(s)
- Ziyan Wang
- Geisel School of Medicine at Dartmouth, Department of Molecular and Systems Biology, Hanover, NH, USA
| | - Bradley M Bartholomai
- Geisel School of Medicine at Dartmouth, Department of Molecular and Systems Biology, Hanover, NH, USA
| | - Jennifer J Loros
- Geisel School of Medicine at Dartmouth, Department of Biochemistry and Cell Biology, Hanover, NH, USA
| | - Jay C Dunlap
- Geisel School of Medicine at Dartmouth, Department of Molecular and Systems Biology, Hanover, NH, USA.
| |
Collapse
|
5
|
Bartholomai BM, Gladfelter AS, Loros JJ, Dunlap JC. PRD-2 mediates clock-regulated perinuclear localization of clock gene RNAs within the circadian cycle of Neurospora. Proc Natl Acad Sci U S A 2022; 119:e2203078119. [PMID: 35881801 PMCID: PMC9351534 DOI: 10.1073/pnas.2203078119] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2022] [Accepted: 06/24/2022] [Indexed: 02/02/2023] Open
Abstract
The transcription-translation negative feedback loops underlying animal and fungal circadian clocks are remarkably similar in their molecular regulatory architecture and, although much is understood about their central mechanism, little is known about the spatiotemporal dynamics of the gene products involved. A common feature of these circadian oscillators is a significant temporal delay between rhythmic accumulation of clock messenger RNAs (mRNAs) encoding negative arm proteins, for example, frq in Neurospora and Per1-3 in mammals, and the appearance of the clock protein complexes assembled from the proteins they encode. Here, we report use of single-molecule RNA fluorescence in situ hybridization (smFISH) to show that the fraction of nuclei actively transcribing the clock gene frq changes in a circadian manner, and that these mRNAs cycle in abundance with fewer than five transcripts per nucleus at any time. Spatial point patterning statistics reveal that frq is spatially clustered near nuclei in a time of day-dependent manner and that clustering requires an RNA-binding protein, PRD-2 (PERIOD-2), recently shown also to bind to mRNA encoding another core clock component, casein kinase 1. An intrinsically disordered protein, PRD-2 displays behavior in vivo and in vitro consistent with participation in biomolecular condensates. These data are consistent with a role for phase-separating RNA-binding proteins in spatiotemporally organizing clock mRNAs to facilitate local translation and assembly of clock protein complexes.
Collapse
Affiliation(s)
- Bradley M. Bartholomai
- Department of Molecular and Systems Biology, Geisel School of Medicine at Dartmouth, Hanover, NH 03755
| | - Amy S. Gladfelter
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599
| | - Jennifer J. Loros
- Department of Biochemistry and Cell Biology, Geisel School of Medicine at Dartmouth, Hanover, NH 03755
| | - Jay C. Dunlap
- Department of Molecular and Systems Biology, Geisel School of Medicine at Dartmouth, Hanover, NH 03755
| |
Collapse
|
6
|
Bartholomai BM, Gladfelter AS, Loros JJ, Dunlap JC. Quantitative single molecule RNA-FISH and RNase-free cell wall digestion in Neurospora crassa. Fungal Genet Biol 2021; 156:103615. [PMID: 34425213 PMCID: PMC8463489 DOI: 10.1016/j.fgb.2021.103615] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2021] [Revised: 08/13/2021] [Accepted: 08/15/2021] [Indexed: 10/20/2022]
Abstract
Single molecule RNA-FISH (smFISH) is a valuable tool for analysis of mRNA spatial patterning in fixed cells that is underutilized in filamentous fungi. A primary complication for fixed-cell imaging in filamentous fungi is the need for enzymatic cell wall permeabilization, which is compounded by considerable variability in cell wall composition between species. smFISH adds another layer of complexity due to a requirement for RNase free conditions. Here, we describe the cloning, expression, and purification of a chitinase suitable for supplementation of a commercially available RNase-free enzyme preparation for efficient permeabilization of the Neurospora cell wall. We further provide a method for smFISH in Neurospora which includes a tool for generating numerical data from images that can be used in downstream customized analysis protocols.
Collapse
Affiliation(s)
- Bradley M Bartholomai
- Geisel School of Medicine at Dartmouth, Department of Molecular and Systems Biology, Hanover, NH, USA
| | - Amy S Gladfelter
- University of North Carolina, Department of Biology, Chapel Hill, NC, USA
| | - Jennifer J Loros
- Geisel School of Medicine at Dartmouth, Department of Biochemistry and Cell Biology, Hanover, NH, USA
| | - Jay C Dunlap
- Geisel School of Medicine at Dartmouth, Department of Molecular and Systems Biology, Hanover, NH, USA.
| |
Collapse
|
7
|
Kelliher CM, Lambreghts R, Xiang Q, Baker CL, Loros JJ, Dunlap JC. PRD-2 directly regulates casein kinase I and counteracts nonsense-mediated decay in the Neurospora circadian clock. eLife 2020; 9:64007. [PMID: 33295874 PMCID: PMC7746235 DOI: 10.7554/elife.64007] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2020] [Accepted: 12/08/2020] [Indexed: 01/22/2023] Open
Abstract
Circadian clocks in fungi and animals are driven by a functionally conserved transcription–translation feedback loop. In Neurospora crassa, negative feedback is executed by a complex of Frequency (FRQ), FRQ-interacting RNA helicase (FRH), and casein kinase I (CKI), which inhibits the activity of the clock’s positive arm, the White Collar Complex (WCC). Here, we show that the prd-2 (period-2) gene, whose mutation is characterized by recessive inheritance of a long 26 hr period phenotype, encodes an RNA-binding protein that stabilizes the ck-1a transcript, resulting in CKI protein levels sufficient for normal rhythmicity. Moreover, by examining the molecular basis for the short circadian period of upf-1prd-6 mutants, we uncovered a strong influence of the Nonsense-Mediated Decay pathway on CKI levels. The finding that circadian period defects in two classically derived Neurospora clock mutants each arise from disruption of ck-1a regulation is consistent with circadian period being exquisitely sensitive to levels of casein kinase I.
Collapse
Affiliation(s)
- Christina M Kelliher
- Department of Molecular & Systems Biology, Geisel School of Medicine at Dartmouth, Hanover, United States
| | - Randy Lambreghts
- Department of Molecular & Systems Biology, Geisel School of Medicine at Dartmouth, Hanover, United States
| | - Qijun Xiang
- Department of Molecular & Systems Biology, Geisel School of Medicine at Dartmouth, Hanover, United States
| | - Christopher L Baker
- Department of Molecular & Systems Biology, Geisel School of Medicine at Dartmouth, Hanover, United States.,The Jackson Laboratory, Bar Harbor, United States
| | - Jennifer J Loros
- Department of Biochemistry & Cell Biology, Geisel School of Medicine at Dartmouth, Hanover, United States
| | - Jay C Dunlap
- Department of Molecular & Systems Biology, Geisel School of Medicine at Dartmouth, Hanover, United States
| |
Collapse
|
8
|
Crowell AM, Greene CS, Loros JJ, Dunlap JC. Learning and Imputation for Mass-spec Bias Reduction (LIMBR). Bioinformatics 2020; 35:1518-1526. [PMID: 30247517 DOI: 10.1093/bioinformatics/bty828] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2018] [Revised: 09/14/2018] [Accepted: 09/23/2018] [Indexed: 12/13/2022] Open
Abstract
MOTIVATION Decreasing costs are making it feasible to perform time series proteomics and genomics experiments with more replicates and higher resolution than ever before. With more replicates and time points, proteome and genome-wide patterns of expression are more readily discernible. These larger experiments require more batches exacerbating batch effects and increasing the number of bias trends. In the case of proteomics, where methods frequently result in missing data this increasing scale is also decreasing the number of peptides observed in all samples. The sources of batch effects and missing data are incompletely understood necessitating novel techniques. RESULTS Here we show that by exploiting the structure of time series experiments, it is possible to accurately and reproducibly model and remove batch effects. We implement Learning and Imputation for Mass-spec Bias Reduction (LIMBR) software, which builds on previous block-based models of batch effects and includes features specific to time series and circadian studies. To aid in the analysis of time series proteomics experiments, which are often plagued with missing data points, we also integrate an imputation system. By building LIMBR for imputation and time series tailored bias modeling into one straightforward software package, we expect that the quality and ease of large-scale proteomics and genomics time series experiments will be significantly increased. AVAILABILITY AND IMPLEMENTATION Python code and documentation is available for download at https://github.com/aleccrowell/LIMBR and LIMBR can be downloaded and installed with dependencies using 'pip install limbr'. SUPPLEMENTARY INFORMATION Supplementary data are available at Bioinformatics online.
Collapse
Affiliation(s)
- Alexander M Crowell
- Department of Molecular and Systems Biology, Geisel School of Medicine at Dartmouth, Hanover, NH, USA
| | - Casey S Greene
- Department of Systems Pharmacology and Translational Therapeutics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Jennifer J Loros
- Department of Biochemistry and Cell Biology, Geisel School of Medicine at Dartmouth, Hanover, NH, USA
| | - Jay C Dunlap
- Department of Molecular and Systems Biology, Geisel School of Medicine at Dartmouth, Hanover, NH, USA
| |
Collapse
|
9
|
Chen S, Fuller KK, Dunlap JC, Loros JJ. A Pro- and Anti-inflammatory Axis Modulates the Macrophage Circadian Clock. Front Immunol 2020; 11:867. [PMID: 32477351 PMCID: PMC7240016 DOI: 10.3389/fimmu.2020.00867] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2020] [Accepted: 04/15/2020] [Indexed: 12/17/2022] Open
Abstract
The circadian clock broadly governs immune cell function, leading to time-of-day differences in inflammatory responses and subsequently, pathogen clearance. However, the effect of inflammatory signals on circadian machinery is poorly understood. We found that in bone marrow-derived macrophages, some host-derived pro-inflammatory cytokines, e.g., IFN-γ or TNF-α, and pathogen-associated molecular patterns, e.g., LPS or Pam3Csk4, suppress the amplitude in oscillations of circadian negative feedback arm clock components such as PER2, and when examined, specific combinations of these immune-related signals suppressed the amplitude of these oscillations to a greater degree in both bone marrow-derived and peritoneal macrophages. At the transcript level, multiple components of the circadian clock were affected in different ways by pro-inflammatory stimulus, including Per2 and Nr1d1. This suppressive effect on PER2 did not arise from nor correlate with cell death or clock resetting. Suppression of the clock by IFN-γ was dependent on its cognate receptor; however, pharmacological inhibition of the canonical JAK/STAT and MEK pathways did not hinder suppression, suggesting a mechanism involving a non-canonical pathway. In contrast, anti-inflammatory signals such as IL-4 and dexamethasone enhanced the expression of PER2 protein and Per2 mRNA. Our results suggest that the circadian system in macrophages can differentially respond to pro- and anti-inflammatory signals in their microenvironments.
Collapse
Affiliation(s)
- Shan Chen
- Department of Molecular and Systems Biology, Geisel School of Medicine at Dartmouth, Hanover, NH, United States
| | - Kevin K Fuller
- Department of Molecular and Systems Biology, Geisel School of Medicine at Dartmouth, Hanover, NH, United States
| | - Jay C Dunlap
- Department of Molecular and Systems Biology, Geisel School of Medicine at Dartmouth, Hanover, NH, United States
| | - Jennifer J Loros
- Department of Molecular and Systems Biology, Geisel School of Medicine at Dartmouth, Hanover, NH, United States.,Department of Biochemistry and Cell Biology, Geisel School of Medicine at Dartmouth, Hanover, NH, United States
| |
Collapse
|
10
|
Kelliher CM, Loros JJ, Dunlap JC. Evaluating the circadian rhythm and response to glucose addition in dispersed growth cultures of Neurospora crassa. Fungal Biol 2019; 124:398-406. [PMID: 32389302 DOI: 10.1016/j.funbio.2019.11.004] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2019] [Revised: 11/12/2019] [Accepted: 11/13/2019] [Indexed: 12/12/2022]
Abstract
Work on the filamentous fungus Neurospora crassa has contributed to or pioneered many aspects of research on circadian clock mechanism, a process that is functionally conserved across eukaryotes. Biochemical assays of the fungal circadian clock typically involve growth in liquid medium where Neurospora forms a spherical ball of submerged mycelium. Here, we revive a method for dispersed growth of Neurospora in batch culture using polyacrylic acid as an additive to the medium. We demonstrate that dispersed growth cultures utilize more carbon than mycelial balls, but nonetheless retain a functional circadian clock. This culturing method is suited for use in circadian experiments where uniform exposure to nutrients and/or increased biomass is required.
Collapse
Affiliation(s)
- Christina M Kelliher
- Department of Molecular & Systems Biology, Geisel School of Medicine at Dartmouth, Hanover, NH, USA
| | - Jennifer J Loros
- Department of Biochemistry & Cell Biology, Geisel School of Medicine at Dartmouth, Hanover, NH, USA
| | - Jay C Dunlap
- Department of Molecular & Systems Biology, Geisel School of Medicine at Dartmouth, Hanover, NH, USA.
| |
Collapse
|
11
|
Loros JJ. Principles of the animal molecular clock learned from Neurospora. Eur J Neurosci 2019; 51:19-33. [PMID: 30687965 DOI: 10.1111/ejn.14354] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2018] [Revised: 12/10/2018] [Accepted: 12/13/2018] [Indexed: 12/28/2022]
Abstract
Study of Neurospora, a model system evolutionarily related to animals and sharing a circadian system having nearly identical regulatory architecture to that of animals, has advanced our understanding of all circadian rhythms. Work on the molecular bases of the Oscillator began in Neurospora before any clock genes were cloned and provided the second example of a clock gene, frq, as well as the first direct experimental proof that the core of the Oscillator was built around a transcriptional translational negative feedback loop (TTFL). Proof that FRQ was a clock component provided the basis for understanding how light resets the clock, and this in turn provided the generally accepted understanding for how light resets all animal and fungal clocks. Experiments probing the mechanism of light resetting led to the first identification of a heterodimeric transcriptional activator as the positive element in a circadian feedback loop, and to the general description of the fungal/animal clock as a single step TTFL. The common means through which DNA damage impacts the Oscillator in fungi and animals was first described in Neurospora. Lastly, the systematic study of Output was pioneered in Neurospora, providing the vocabulary and conceptual framework for understanding how Output works in all cells. This model system has contributed to the current appreciation of the role of Intrinsic Disorder in clock proteins and to the documentation of the essential roles of protein post-translational modification, as distinct from turnover, in building a circadian clock.
Collapse
Affiliation(s)
- Jennifer J Loros
- Department of Biochemistry and Cell Biology, Geisel School of Medicine at Dartmouth, Hanover, New Hampshire.,Department of Molecular and Systems Biology, Geisel School of Medicine at Dartmouth, Hanover, New Hampshire
| |
Collapse
|
12
|
Fuller KK, Dunlap JC, Loros JJ. Light-regulated promoters for tunable, temporal, and affordable control of fungal gene expression. Appl Microbiol Biotechnol 2018; 102:3849-3863. [PMID: 29569180 DOI: 10.1007/s00253-018-8887-7] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2017] [Revised: 02/19/2018] [Accepted: 02/20/2018] [Indexed: 01/08/2023]
Abstract
Regulatable promoters are important genetic tools, particularly for assigning function to essential and redundant genes. They can also be used to control the expression of enzymes that influence metabolic flux or protein secretion, thereby optimizing product yield in bioindustry. This review will focus on regulatable systems for use in filamentous fungi, an important group of organisms whose members include key research models, devastating pathogens of plants and animals, and exploitable cell factories. Though we will begin by cataloging those promoters that are controlled by nutritional or chemical means, our primary focus will rest on those who can be controlled by a literal flip-of-the-switch: promoters of light-regulated genes. The vvd promoter of Neurospora will first serve as a paradigm for how light-driven systems can provide tight, robust, tunable, and temporal control of either autologous or heterologous fungal proteins. We will then discuss a theoretical approach to, and practical considerations for, the development of such promoters in other species. To this end, we have compiled genes from six previously published light-regulated transcriptomic studies to guide the search for suitable photoregulatable promoters in your fungus of interest.
Collapse
Affiliation(s)
- Kevin K Fuller
- Department of Molecular and Systems Biology, Geisel School of Medicine, Hanover, NH, USA.
| | - Jay C Dunlap
- Department of Molecular and Systems Biology, Geisel School of Medicine, Hanover, NH, USA
| | - Jennifer J Loros
- Department of Molecular and Systems Biology, Geisel School of Medicine, Hanover, NH, USA. .,Department of Biochemistry and Cell Biology, Geisel School of Medicine, Hanover, NH, USA.
| |
Collapse
|
13
|
Zhou X, Wang B, Emerson JM, Ringelberg CS, Gerber SA, Loros JJ, Dunlap JC. A HAD family phosphatase CSP-6 regulates the circadian output pathway in Neurospora crassa. PLoS Genet 2018; 14:e1007192. [PMID: 29351294 PMCID: PMC5800702 DOI: 10.1371/journal.pgen.1007192] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2017] [Revised: 02/06/2018] [Accepted: 01/08/2018] [Indexed: 01/24/2023] Open
Abstract
Circadian clocks are ubiquitous in eukaryotic organisms where they are used to anticipate regularly occurring diurnal and seasonal environmental changes. Nevertheless, little is known regarding pathways connecting the core clock to its output pathways. Here, we report that the HAD family phosphatase CSP-6 is required for overt circadian clock output but not for the core oscillation. The loss of function Δcsp-6 deletion mutant is overtly arrhythmic on race tubes under free running conditions; however, reporter assays confirm that the FREQUENCY-WHITE COLLAR COMPLEX core circadian oscillator is functional, indicating a discrete block between oscillator and output. CSP-6 physically interacts with WHI-2, Δwhi-2 mutant phenotypes resemble Δcsp-6, and the CSP-6/WHI-2 complex physically interacts with WC-1, all suggesting that WC-1 is a direct target for CSP-6/WHI-2-mediated dephosphorylation and consistent with observed WC-1 hyperphosphorylation in Δcsp-6. To identify the source of the block to output, known clock-controlled transcription factors were screened for rhythmicity in Δcsp-6, identifying loss of circadian control of ADV-1, a direct target of WC-1, as responsible for the loss of overt rhythmicity. The CSP-6/WHI-2 complex thus participates in the clock output pathway by regulating WC-1 phosphorylation to promote proper transcriptional/translational activation of adv-1/ADV-1; these data establish an unexpected essential role for post-translational modification parallel to circadian transcriptional regulation in the early steps of circadian output. Though molecules and components in the core circadian oscillator are well studied in Neurospora, the mechanisms through which output pathways are coupled with core components are less well understood. In this study we investigated a HAD phosphatase, CSP-6; loss-of-function Δcsp-6 strains are overtly arrhythmic but have a functional core circadian oscillation. CSP-6 in association with WHI-2 dephosphorylates the core clock component WC-1 to regulate light-responses and development. To dissect the functions of CSP-6 in core clock and output, we screened known WC-1 targets and found that loss of CSP-6 causes misregulation of transcriptional/translational activation of ADV-1, a key regulator of output. Thus, loss of CSP-6-mediated dephosphorylation of WC-1 leads to loss of ADV-1 activation and is responsible for the complete loss of overt developmental rhythmicity in Δcsp-6.
Collapse
Affiliation(s)
- Xiaoying Zhou
- Department of Molecular and Systems Biology, Geisel School of Medicine, Dartmouth, Hanover, New Hampshire, United States of America
| | - Bin Wang
- Department of Molecular and Systems Biology, Geisel School of Medicine, Dartmouth, Hanover, New Hampshire, United States of America
| | - Jillian M. Emerson
- Department of Molecular and Systems Biology, Geisel School of Medicine, Dartmouth, Hanover, New Hampshire, United States of America
| | - Carol S. Ringelberg
- Department of Molecular and Systems Biology, Geisel School of Medicine, Dartmouth, Hanover, New Hampshire, United States of America
| | - Scott A. Gerber
- Department of Molecular and Systems Biology, Geisel School of Medicine, Dartmouth, Hanover, New Hampshire, United States of America
- Biochemistry and Cell Biology, Geisel School of Medicine, Dartmouth, Hanover, New Hampshire, United States of America
- Norris Cotton Cancer Center, Geisel School of Medicine at Dartmouth, Hanover, New Hampshire, United States of America
| | - Jennifer J. Loros
- Biochemistry and Cell Biology, Geisel School of Medicine, Dartmouth, Hanover, New Hampshire, United States of America
| | - Jay C. Dunlap
- Department of Molecular and Systems Biology, Geisel School of Medicine, Dartmouth, Hanover, New Hampshire, United States of America
- * E-mail:
| |
Collapse
|
14
|
Chen S, Fuller KK, Dunlap JC, Loros JJ. Circadian Clearance of a Fungal Pathogen from the Lung Is Not Based on Cell-intrinsic Macrophage Rhythms. J Biol Rhythms 2017; 33:99-105. [PMID: 29281921 DOI: 10.1177/0748730417745178] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Circadian rhythms govern immune cell function, giving rise to time-of-day variation in the recognition and clearance of bacterial or viral pathogens; to date, however, no such regulation of the host-fungal interaction has been described. In this report, we use murine models to explore circadian control of either fungal-macrophage interactions in vitro or pathogen clearance from the lung in vivo. First, we show that expression of the important fungal pattern recognition receptor Dectin-1 ( clec7a), from either bone marrow-derived or peritoneum-derived macrophages, is not under circadian regulation at either the level of transcript or cell surface protein expression. Consistent with this finding, the phagocytic activity of macrophages in culture against spores of the pathogen Aspergillus fumigatus also did not vary over time. To account for the multiple cell types and processes that may be coordinated in a circadian fashion in vivo, we examined the clearance of A. fumigatus from the lungs of immunocompetent mice. Interestingly, animals inoculated at night demonstrated a 2-fold enhancement in clearance compared with animals inoculated in the morning. Taken together, our data suggest that while molecular recognition of fungi by immune cells may not be circadian, other processes in vivo may still allow for time-of-day differences in fungal clearance from the lung.
Collapse
Affiliation(s)
- Shan Chen
- Department of Molecular and Systems Biology, Geisel School of Medicine at Dartmouth, Hanover, NH
| | - Kevin K Fuller
- Department of Molecular and Systems Biology, Geisel School of Medicine at Dartmouth, Hanover, NH
| | - Jay C Dunlap
- Department of Molecular and Systems Biology, Geisel School of Medicine at Dartmouth, Hanover, NH
| | - Jennifer J Loros
- Department of Molecular and Systems Biology, Geisel School of Medicine at Dartmouth, Hanover, NH.,Department of Biochemistry and Cell Biology, Geisel School of Medicine at Dartmouth, Hanover, NH
| |
Collapse
|
15
|
Dunlap JC, Loros JJ. Just-So Stories and Origin Myths: Phosphorylation and Structural Disorder in Circadian Clock Proteins. Mol Cell 2017; 69:165-168. [PMID: 29276084 DOI: 10.1016/j.molcel.2017.11.028] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2017] [Revised: 10/19/2017] [Accepted: 11/20/2017] [Indexed: 11/28/2022]
Abstract
Some longstanding dogmas in the circadian field warrant reexamination in light of recent studies focused on the role of post-translational modifications and intrinsic disorder in core circadian clock proteins of mice and fungi. Such dogmas include the role of turnover in circadian feedback loops and the origin myths describing evolutionary relatedness among circadian clocks. In this Essay, the authors recapitulate recent findings on circadian clock protein regulation by taking an unconventional approach in the form of a dialog between Wizard and Apprentice.
Collapse
Affiliation(s)
- Jay C Dunlap
- Department of Molecular and Systems Biology, Geisel School of Medicine at Dartmouth, Hanover, NH 03755.
| | - Jennifer J Loros
- Department of Biochemistry and Cell Biology, Geisel School of Medicine at Dartmouth, Hanover, NH 03755
| |
Collapse
|
16
|
Hughes ME, Abruzzi KC, Allada R, Anafi R, Arpat AB, Asher G, Baldi P, de Bekker C, Bell-Pedersen D, Blau J, Brown S, Ceriani MF, Chen Z, Chiu JC, Cox J, Crowell AM, DeBruyne JP, Dijk DJ, DiTacchio L, Doyle FJ, Duffield GE, Dunlap JC, Eckel-Mahan K, Esser KA, FitzGerald GA, Forger DB, Francey LJ, Fu YH, Gachon F, Gatfield D, de Goede P, Golden SS, Green C, Harer J, Harmer S, Haspel J, Hastings MH, Herzel H, Herzog ED, Hoffmann C, Hong C, Hughey JJ, Hurley JM, de la Iglesia HO, Johnson C, Kay SA, Koike N, Kornacker K, Kramer A, Lamia K, Leise T, Lewis SA, Li J, Li X, Liu AC, Loros JJ, Martino TA, Menet JS, Merrow M, Millar AJ, Mockler T, Naef F, Nagoshi E, Nitabach MN, Olmedo M, Nusinow DA, Ptáček LJ, Rand D, Reddy AB, Robles MS, Roenneberg T, Rosbash M, Ruben MD, Rund SSC, Sancar A, Sassone-Corsi P, Sehgal A, Sherrill-Mix S, Skene DJ, Storch KF, Takahashi JS, Ueda HR, Wang H, Weitz C, Westermark PO, Wijnen H, Xu Y, Wu G, Yoo SH, Young M, Zhang EE, Zielinski T, Hogenesch JB. Guidelines for Genome-Scale Analysis of Biological Rhythms. J Biol Rhythms 2017; 32:380-393. [PMID: 29098954 PMCID: PMC5692188 DOI: 10.1177/0748730417728663] [Citation(s) in RCA: 155] [Impact Index Per Article: 22.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Genome biology approaches have made enormous contributions to our understanding of biological rhythms, particularly in identifying outputs of the clock, including RNAs, proteins, and metabolites, whose abundance oscillates throughout the day. These methods hold significant promise for future discovery, particularly when combined with computational modeling. However, genome-scale experiments are costly and laborious, yielding “big data” that are conceptually and statistically difficult to analyze. There is no obvious consensus regarding design or analysis. Here we discuss the relevant technical considerations to generate reproducible, statistically sound, and broadly useful genome-scale data. Rather than suggest a set of rigid rules, we aim to codify principles by which investigators, reviewers, and readers of the primary literature can evaluate the suitability of different experimental designs for measuring different aspects of biological rhythms. We introduce CircaInSilico, a web-based application for generating synthetic genome biology data to benchmark statistical methods for studying biological rhythms. Finally, we discuss several unmet analytical needs, including applications to clinical medicine, and suggest productive avenues to address them.
Collapse
Affiliation(s)
- Michael E Hughes
- 1 Division of Pulmonary and Critical Care Medicine, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Katherine C Abruzzi
- 2 Department of Biology and Howard Hughes Medical Institute, Brandeis University, Waltham, Massachusetts, USA
| | - Ravi Allada
- 3 Department of Neurobiology, Northwestern University, Evanston, Illinois, USA
| | - Ron Anafi
- 4 Division of Sleep Medicine, Department of Medicine, University of Pennsylvania Perelman School of Medicine, Philadelphia, USA
| | - Alaaddin Bulak Arpat
- 5 Center for Integrative Genomics, Génopode, University of Lausanne, Lausanne, Switzerland.,6 Vital-IT, Swiss Institute of Bioinformatics, Lausanne, Switzerland
| | - Gad Asher
- 7 Department of Biomolecular Sciences, Weizmann Institute of Science, Rehovot, Israel
| | - Pierre Baldi
- 8 Institute for Genomics and Bioinformatics, University of California, Irvine, USA
| | | | | | - Justin Blau
- 11 Department of Biology, New York University, New York, USA
| | - Steve Brown
- 12 Institute of Pharmacology and Toxicology, University of Zürich, Switzerland
| | - M Fernanda Ceriani
- 13 Laboratorio de Genética del Comportamiento, Fundación Instituto Leloir, IIBBA-CONICET, Buenos Aires, Argentina
| | - Zheng Chen
- 14 Department of Biochemistry and Molecular Biology, University of Texas Health Science Center, Houston, USA
| | - Joanna C Chiu
- 15 Department of Entomology and Nematology, University of California, Davis, USA
| | - Juergen Cox
- 16 Computational Systems Biochemistry, Max-Planck Institute of Biochemistry, Martinsried, Germany
| | - Alexander M Crowell
- 17 Department of Molecular and Systems Biology, Geisel School of Medicine at Dartmouth, Hanover, New Hampshire, USA
| | - Jason P DeBruyne
- 18 Department of Pharmacology and Toxicology, Morehouse School of Medicine, Atlanta, Georgia, USA
| | - Derk-Jan Dijk
- 19 Surrey Sleep Research Centre, University of Surrey, Guildford, UK
| | - Luciano DiTacchio
- 20 The University of Kansas Medical Center, University of Kansas, Kansas City, USA
| | - Francis J Doyle
- 21 John A. Paulson School of Engineering and Applied Sciences, Harvard University, Boston, Massachusetts, USA
| | - Giles E Duffield
- 22 Department of Biological Sciences and Eck Institute for Global Health, University of Notre Dame, Notre Dame, Indiana, USA
| | - Jay C Dunlap
- 17 Department of Molecular and Systems Biology, Geisel School of Medicine at Dartmouth, Hanover, New Hampshire, USA
| | - Kristin Eckel-Mahan
- 23 Institute of Molecular Medicine, McGovern Medical School, UT Health Houston, Houston, Texas, USA
| | - Karyn A Esser
- 24 Department of Physiology and Functional Genomics, University of Florida College of Medicine, Gainesville, USA
| | - Garret A FitzGerald
- 25 Systems Pharmacology and Translational Therapeutics, University of Pennsylvania Perelman School of Medicine, Philadelphia, USA
| | - Daniel B Forger
- 26 Department of Mathematics, University of Michigan, Ann Arbor, USA
| | - Lauren J Francey
- 27 Department of Pediatrics, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio, USA
| | - Ying-Hui Fu
- 28 Kavli Institute for Fundamental Neuroscience, Weill Institute of Neuroscience, Department of Neurology, University of California, San Francisco, USA
| | - Frédéric Gachon
- 29 Department of Diabetes and Circadian Rhythms, Nestlé Institute of Health Sciences, Lausanne, Switzerland
| | - David Gatfield
- 5 Center for Integrative Genomics, Génopode, University of Lausanne, Lausanne, Switzerland
| | - Paul de Goede
- 30 Department of Endocrinology & Metabolism, Academic Medical Center, Amsterdam, the Netherlands
| | - Susan S Golden
- 31 Center for Circadian Biology and Division of Biological Sciences, University of California, San Diego, La Jolla, USA
| | - Carla Green
- 32 Department of Neuroscience, University of Texas Southwestern Medical Center, Dallas, USA
| | - John Harer
- 33 Department of Mathematics, Duke University, Durham, North Carolina, USA
| | - Stacey Harmer
- 34 Department of Plant Biology, University of California, Davis, USA
| | - Jeff Haspel
- 1 Division of Pulmonary and Critical Care Medicine, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Michael H Hastings
- 35 Medical Research Council Laboratory of Molecular Biology, Cambridge, UK
| | - Hanspeter Herzel
- 36 Institute for Theoretical Biology, Charité-Universitätsmedizin Berlin, Germany
| | - Erik D Herzog
- 37 Department of Biology, Washington University in St. Louis, Missouri, USA
| | - Christy Hoffmann
- 1 Division of Pulmonary and Critical Care Medicine, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Christian Hong
- 27 Department of Pediatrics, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio, USA
| | - Jacob J Hughey
- 38 Department of Biomedical Informatics, Vanderbilt University School of Medicine, Nashville, Tennessee, USA
| | - Jennifer M Hurley
- 39 Department of Biological Sciences, Rensselaer Polytechnic Institute, Troy, New York, USA
| | | | - Carl Johnson
- 41 Department of Biological Sciences, Vanderbilt University, Nashville, Tennessee, USA
| | - Steve A Kay
- 42 Department of Cell and Molecular Biology, The Scripps Research Institute, University of California, San Diego, La Jolla, USA
| | - Nobuya Koike
- 43 Department of Physiology and Systems Bioscience, Kyoto Prefectural University of Medicine, Japan
| | - Karl Kornacker
- 44 Division of Sensory Biophysics, The Ohio State University, Columbus, USA
| | - Achim Kramer
- 45 Laboratory of Chronobiology, Charité Universitätsmedizin Berlin, Germany
| | - Katja Lamia
- 46 Department of Molecular Medicine, The Scripps Research Institute, La Jolla, California, USA
| | - Tanya Leise
- 47 Department of Mathematics and Statistics, Amherst College, Amherst, Massachusetts, USA
| | - Scott A Lewis
- 1 Division of Pulmonary and Critical Care Medicine, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Jiajia Li
- 1 Division of Pulmonary and Critical Care Medicine, Washington University School of Medicine, St. Louis, Missouri, USA.,48 Department of Biology, University of Missouri-St. Louis, USA
| | - Xiaodong Li
- 49 Department of Cell Biology, College of Life Sciences at Wuhan University, China
| | - Andrew C Liu
- 50 Department of Biological Sciences, University of Memphis, Tennessee, USA
| | - Jennifer J Loros
- 51 Department of Biochemistry and Cell Biology, Geisel School of Medicine at Dartmouth, Hanover, New Hampshire, USA
| | - Tami A Martino
- 52 Centre for Cardiovascular Investigations, Department of Biomedical Sciences, University of Guelph, Guelph, Ontario, Canada
| | - Jerome S Menet
- 10 Department of Biology, Texas A&M University, College Station, USA
| | - Martha Merrow
- 53 Institute of Medical Psychology, Faculty of Medicine, LMU Munich, Germany
| | - Andrew J Millar
- 54 SynthSys and School of Biological Sciences, University of Edinburgh, UK
| | - Todd Mockler
- 55 Donald Danforth Plant Science Center, St. Louis, Missouri, USA
| | - Felix Naef
- 56 The Institute of Bioengineering, School of Life Sciences, Ecole Polytechnique Fédérale de Lausanne, Switzerland
| | - Emi Nagoshi
- 57 Department of Genetics and Evolution, University of Geneva, Switzerland
| | - Michael N Nitabach
- 58 Department of Cellular and Molecular Physiology, Department of Genetics, Kavli Institute for Neuroscience, Yale School of Medicine, New Haven, Connecticut, USA
| | - Maria Olmedo
- 59 Department of Genetics, University of Seville, Spain
| | - Dmitri A Nusinow
- 55 Donald Danforth Plant Science Center, St. Louis, Missouri, USA
| | - Louis J Ptáček
- 60 Department of Neurology, University of California, San Francisco, USA
| | - David Rand
- 61 Warwick Systems Biology and Mathematics Institute, University of Warwick, Conventry, UK
| | - Akhilesh B Reddy
- 62 The Francis Crick Institute, London, UK, and UCL Institute of Neurology, Queen Square, London, UK
| | - Maria S Robles
- 53 Institute of Medical Psychology, Faculty of Medicine, LMU Munich, Germany
| | - Till Roenneberg
- 53 Institute of Medical Psychology, Faculty of Medicine, LMU Munich, Germany
| | - Michael Rosbash
- 2 Department of Biology and Howard Hughes Medical Institute, Brandeis University, Waltham, Massachusetts, USA
| | - Marc D Ruben
- 27 Department of Pediatrics, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio, USA
| | - Samuel S C Rund
- 63 Centre for Immunity, Infection and Evolution, University of Edinburgh, UK
| | - Aziz Sancar
- 64 Department of Biochemistry and Biophysics, University of North Carolina, Chapel Hill, USA
| | - Paolo Sassone-Corsi
- 65 Department of Biological Chemistry, Center for Epigenetics and Metabolism, University of California, Irvine, USA
| | - Amita Sehgal
- 66 Howard Hughes Medical Institute, University of Pennsylvania Perelman School of Medicine, Philadelphia, USA
| | - Scott Sherrill-Mix
- 67 Department of Microbiology, University of Pennsylvania Perelman School of Medicine, Philadelphia, USA
| | - Debra J Skene
- 68 Chronobiology, Faculty of Health and Medical Sciences, University of Surrey, Guildford, UK
| | - Kai-Florian Storch
- 69 Department of Psychiatry, Douglas Mental Health University Institute, McGill University, Montreal, Canada
| | - Joseph S Takahashi
- 70 Howard Hughes Medical Institute, Department of Neuroscience, University of Texas Southwestern Medical Center, Dallas, USA
| | - Hiroki R Ueda
- 71 Department of Systems Pharmacology, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan Laboratory for Synthetic Biology, RIKEN Quantitative Biology Center, Osaka, Japan
| | - Han Wang
- 72 Center for Circadian Clocks, Soochow University, Suzhou, Jiangsu, China
| | - Charles Weitz
- 73 Department of Neurobiology, Harvard Medical School, Boston, Massachusetts, USA
| | - Pål O Westermark
- 74 Institute of Genetics and Biometry, Leibniz Institute for Farm Animal Biology, Dummerstorf, Germany
| | - Herman Wijnen
- 75 Biological Sciences and Institute for Life Sciences, University of Southampton, UK
| | - Ying Xu
- 76 Cam-Su GRC, Soochow University, Suzhou, China
| | - Gang Wu
- 27 Department of Pediatrics, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio, USA
| | - Seung-Hee Yoo
- 14 Department of Biochemistry and Molecular Biology, University of Texas Health Science Center, Houston, USA
| | - Michael Young
- 77 Laboratory of Genetics, Rockefeller University, New York, New York, USA
| | | | - Tomasz Zielinski
- 54 SynthSys and School of Biological Sciences, University of Edinburgh, UK
| | - John B Hogenesch
- 27 Department of Pediatrics, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio, USA
| |
Collapse
|
17
|
Abstract
The capacity for biological timekeeping arose at least three times through evolution, in prokaryotic cyanobacteria, in cells that evolved into higher plants, and within the group of organisms that eventually became the fungi and the animals. Neurospora is a tractable model system for understanding the molecular bases of circadian rhythms in the last of these groups, and is perhaps the most intensively studied circadian cell type. Rhythmic processes described in fungi include growth rate, stress responses, developmental capacity, and sporulation, as well as much of metabolism; fungi use clocks to anticipate daily environmental changes. A negative feedback loop comprises the core of the circadian system in fungi and animals. In Neurospora, the best studied fungal model, it is driven by two transcription factors, WC-1 and WC-2, that form the White Collar Complex (WCC). WCC elicits expression of the frq gene. FRQ complexes with other proteins, physically interacts with the WCC, and reduces its activity; the kinetics of these processes is strongly influenced by progressive phosphorylation of FRQ. When FRQ becomes sufficiently phosphorylated that it loses the ability to influence WCC activity, the circadian cycle starts again. Environmental cycles of light and temperature influence frq and FRQ expression and thereby reset the internal circadian clocks. The molecular basis of circadian output is also becoming understood. Taken together, molecular explanations are emerging for all the canonical circadian properties, providing a molecular and regulatory framework that may be extended to many members of the fungal and animal kingdoms, including humans.
Collapse
Affiliation(s)
- Jay C Dunlap
- Department of Molecular and Systems Biology, Geisel School of Medicine at Dartmouth, Hanover, NH 03755
| | - Jennifer J Loros
- Department of Molecular and Systems Biology, Geisel School of Medicine at Dartmouth, Hanover, NH 03755
- Department of Biochemistry and Cell Biology, Geisel School of Medicine at Dartmouth, Hanover, NH 03755
| |
Collapse
|
18
|
Fuller KK, Cramer RA, Zegans ME, Dunlap JC, Loros JJ. Aspergillus fumigatus Photobiology Illuminates the Marked Heterogeneity between Isolates. mBio 2016; 7:e01517-16. [PMID: 27651362 PMCID: PMC5030361 DOI: 10.1128/mbio.01517-16] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2016] [Accepted: 08/22/2016] [Indexed: 11/24/2022] Open
Abstract
UNLABELLED The given strain of Aspergillus fumigatus under study varies across laboratories, ranging from a few widely used "standards," e.g., Af293 or CEA10, to locally acquired isolates that may be unique to one investigator. Since experiments concerning physiology or gene function are seldom replicated by others, i.e., in a different A. fumigatus background, the extent to which behavioral heterogeneity exists within the species is poorly understood. As a proxy for assessing such intraspecies variability, we analyzed the light response of 15 A. fumigatus isolates and observed striking quantitative and qualitative heterogeneity among them. The majority of the isolates fell into one of two seemingly mutually exclusive groups: (i) "photopigmenters" that robustly accumulate hyphal melanin in the light and (ii) "photoconidiators" that induce sporulation in the light. These two distinct responses were both governed by the same upstream blue light receptor, LreA, indicating that a specific protein's contribution can vary in a strain-dependent manner. Indeed, while LreA played no apparent role in regulating cell wall homeostasis in strain Af293, it was essential in that regard in strain CEA10. The manifest heterogeneity in the photoresponses led us to compare the virulence levels of selected isolates in a murine model; remarkably, the virulence did vary greatly, although not in a manner that correlated with their overt light response. Taken together, these data highlight the extent to which isolates of A. fumigatus can vary, with respect to both broad physiological characteristics (e.g., virulence and photoresponse) and specific protein functionality (e.g., LreA-dependent phenotypes). IMPORTANCE The current picture of Aspergillus fumigatus biology is akin to a collage, patched together from data obtained from disparate "wild-type" strains. In a systematic assessment of 15 A. fumigatus isolates, we show that the species is highly heterogeneous with respect to its light response and virulence. Whereas some isolates accumulate pigments in light as previously reported with strain Af293, most induce sporulation which had not been previously observed. Other photoresponsive behaviors are also nonuniform, and phenotypes of identical gene deletants vary in a background-dependent manner. Moreover, the virulence of several selected isolates is highly variable in a mouse model and apparently does not track with any observed light response. Cumulatively, this work illuminates the fact that data obtained with a single A. fumigatus isolate are not necessarily predictive of the species as whole. Accordingly, researchers should be vigilant when making conclusions about their own work or when interpreting data from the literature.
Collapse
Affiliation(s)
- Kevin K Fuller
- Department of Molecular and Systems Biology, Geisel School of Medicine at Dartmouth, Hanover, New Hampshire, USA
| | - Robert A Cramer
- Department of Microbiology and Immunology, Geisel School of Medicine at Dartmouth, Hanover, New Hampshire, USA
| | - Michael E Zegans
- Department of Microbiology and Immunology, Geisel School of Medicine at Dartmouth, Hanover, New Hampshire, USA Department of Surgery (Ophthalmology), Geisel School of Medicine at Dartmouth, Hanover, New Hampshire, USA
| | - Jay C Dunlap
- Department of Molecular and Systems Biology, Geisel School of Medicine at Dartmouth, Hanover, New Hampshire, USA
| | - Jennifer J Loros
- Department of Molecular and Systems Biology, Geisel School of Medicine at Dartmouth, Hanover, New Hampshire, USA Department of Biochemistry and Cell Biology, Geisel School of Medicine at Dartmouth, Hanover, New Hampshire, USA
| |
Collapse
|
19
|
Hurley JM, Loros JJ, Dunlap JC. Circadian Oscillators: Around the Transcription-Translation Feedback Loop and on to Output. Trends Biochem Sci 2016; 41:834-846. [PMID: 27498225 DOI: 10.1016/j.tibs.2016.07.009] [Citation(s) in RCA: 125] [Impact Index Per Article: 15.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2016] [Revised: 07/10/2016] [Accepted: 07/14/2016] [Indexed: 12/20/2022]
Abstract
From cyanobacteria to mammals, organisms have evolved timing mechanisms to adapt to environmental changes in order to optimize survival and improve fitness. To anticipate these regular daily cycles, many organisms manifest ∼24h cell-autonomous oscillations that are sustained by transcription-translation-based or post-transcriptional negative-feedback loops that control a wide range of biological processes. With an eye to identifying emerging common themes among cyanobacterial, fungal, and animal clocks, some major recent developments in the understanding of the mechanisms that regulate these oscillators and their output are discussed. These include roles for antisense transcription, intrinsically disordered proteins, codon bias in clock genes, and a more focused discussion of post-transcriptional and translational regulation as a part of both the oscillator and output.
Collapse
Affiliation(s)
- Jennifer M Hurley
- Department of Biological Sciences, Rensselaer Polytechnic Institute, Troy, NY 12180, USA.
| | - Jennifer J Loros
- Department of Biochemistry and Cell Biology, Geisel School of Medicine at Dartmouth, Hanover, NH 03755, USA
| | - Jay C Dunlap
- Department of Molecular and Systems Biology, Geisel School of Medicine at Dartmouth, Hanover, NH 03755, USA.
| |
Collapse
|
20
|
Abstract
The eukaryotic filamentous fungus Neurospora crassa has proven to be a durable and dependable model system for the analysis of the cellular and molecular bases of circadian rhythms. Pioneering genetic analyses identified clock genes, and beginning with the cloning of frequency ( frq), work over the past 2 decades has revealed the molecular basis of a core circadian clock feedback loop that has illuminated our understanding of circadian oscillators in microbes, plants, and animals. In this transcription/translation-based feedback loop, a heterodimer of the White Collar-1 (WC-1) and WC-2 proteins acts both as the circadian photoreceptor and, in the dark, as a transcription factor that promotes the expression of the frq gene. FRQ dimerizes and feeds back to block the activity of its activators (making a negative feedback loop), as well as feeding forward to promote the synthesis of its activator, WC-1. Phosphorylation of FRQ by several kinases leads to its ubiquitination and turnover, releasing the WC-1/WC-2 dimer to reactivate frq expression and restart the circadian cycle. Light resetting of the clock can be understood through the rapid light induction of frq expression and temperature resetting through the influence of elevated temperaturesin driving higher levels of FRQ. Several FRQ- and WC-independent, noncircadian FRQ-less oscillators (FLOs) have been described, each of which appears to regulate aspects of Neurospora growth or development. Overall, the FRQ/white collar complex feedback loop appears to coordinate the circadian system through its activity to regulate downstream-target clock-controlled genes, either directly or via regulation of driven FLOs.
Collapse
Affiliation(s)
- Jay C Dunlap
- Department of Genetics, Dartmouth Medical School, Hannover, NH 03755-3844, USA.
| | | |
Collapse
|
21
|
Conrad KS, Hurley JM, Widom J, Ringelberg CS, Loros JJ, Dunlap JC, Crane BR. Structure of the frequency-interacting RNA helicase: a protein interaction hub for the circadian clock. EMBO J 2016; 35:1707-19. [PMID: 27340124 PMCID: PMC4969578 DOI: 10.15252/embj.201694327] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2016] [Accepted: 05/23/2016] [Indexed: 11/09/2022] Open
Abstract
In the Neurospora crassa circadian clock, a protein complex of frequency (FRQ), casein kinase 1a (CK1a), and the FRQ-interacting RNA Helicase (FRH) rhythmically represses gene expression by the white-collar complex (WCC). FRH crystal structures in several conformations and bound to ADP/RNA reveal differences between FRH and the yeast homolog Mtr4 that clarify the distinct role of FRH in the clock. The FRQ-interacting region at the FRH N-terminus has variable structure in the absence of FRQ A known mutation that disrupts circadian rhythms (R806H) resides in a positively charged surface of the KOW domain, far removed from the helicase core. We show that changes to other similarly located residues modulate interactions with the WCC and FRQ A V142G substitution near the N-terminus also alters FRQ and WCC binding to FRH, but produces an unusual short clock period. These data support the assertion that FRH helicase activity does not play an essential role in the clock, but rather FRH acts to mediate contacts among FRQ, CK1a and the WCC through interactions involving its N-terminus and KOW module.
Collapse
Affiliation(s)
- Karen S Conrad
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY, USA
| | | | - Joanne Widom
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY, USA
| | | | - Jennifer J Loros
- Department of Biochemistry, Geisel School of Medicine, Hanover, NH, USA
| | - Jay C Dunlap
- Department of Genetics, Geisel School of Medicine, Hanover, NH, USA
| | - Brian R Crane
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY, USA
| |
Collapse
|
22
|
Emerson JM, Bartholomai BM, Ringelberg CS, Baker SE, Loros JJ, Dunlap JC. period-1 encodes an ATP-dependent RNA helicase that influences nutritional compensation of the Neurospora circadian clock. Proc Natl Acad Sci U S A 2015; 112:15707-12. [PMID: 26647184 PMCID: PMC4697410 DOI: 10.1073/pnas.1521918112] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Mutants in the period-1 (prd-1) gene, characterized by a recessive allele, display a reduced growth rate and period lengthening of the developmental cycle controlled by the circadian clock. We refined the genetic location of prd-1 and used whole genome sequencing to find the mutation defining it, confirming the identity of prd-1 by rescuing the mutant circadian phenotype via transformation. PRD-1 is an RNA helicase whose orthologs, DDX5 [DEAD (Asp-Glu-Ala-Asp) Box Helicase 5] and DDX17 in humans and DBP2 (Dead Box Protein 2) in yeast, are implicated in various processes, including transcriptional regulation, elongation, and termination, ribosome biogenesis, and mRNA decay. Although prd-1 mutants display a long period (∼25 h) circadian developmental cycle, they interestingly display a WT period when the core circadian oscillator is tracked using a frq-luciferase transcriptional fusion under conditions of limiting nutritional carbon; the core oscillator in the prd-1 mutant strain runs with a long period under glucose-sufficient conditions. Thus, PRD-1 clearly impacts the circadian oscillator and is not only part of a metabolic oscillator ancillary to the core clock. PRD-1 is an essential protein, and its expression is neither light-regulated nor clock-regulated. However, it is transiently induced by glucose; in the presence of sufficient glucose, PRD-1 is in the nucleus until glucose runs out, which elicits its disappearance from the nucleus. Because circadian period length is carbon concentration-dependent, prd-1 may be formally viewed as a clock mutant with defective nutritional compensation of circadian period length.
Collapse
Affiliation(s)
- Jillian M Emerson
- Department of Genetics, Geisel School of Medicine at Dartmouth, Hanover, NH 03755
| | | | - Carol S Ringelberg
- Department of Genetics, Geisel School of Medicine at Dartmouth, Hanover, NH 03755
| | - Scott E Baker
- Environmental Molecular Sciences Laboratory, Earth and Biological Sciences Directorate, Pacific Northwest National Laboratory, Richland, WA 99354
| | - Jennifer J Loros
- Department of Genetics, Geisel School of Medicine at Dartmouth, Hanover, NH 03755; Department of Biochemistry, Geisel School of Medicine at Dartmouth, Hanover, NH 03755
| | - Jay C Dunlap
- Department of Genetics, Geisel School of Medicine at Dartmouth, Hanover, NH 03755;
| |
Collapse
|
23
|
Dasgupta A, Fuller KK, Dunlap JC, Loros JJ. Seeing the world differently: variability in the photosensory mechanisms of two model fungi. Environ Microbiol 2015; 18:5-20. [PMID: 26373782 DOI: 10.1111/1462-2920.13055] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2015] [Revised: 09/01/2015] [Accepted: 09/12/2015] [Indexed: 12/14/2022]
Abstract
Light plays an important role for most organisms on this planet, serving either as a source of energy or information for the adaptation of biological processes to specific times of day. The fungal kingdom is estimated to contain well over a million species, possibly 10-fold more, and it is estimated that a majority of the fungi respond to light, eliciting changes in several physiological characteristics including pathogenesis, development and secondary metabolism. Two model organisms for photobiological studies have taken centre-stage over the last few decades--Neurospora crassa and Aspergillus nidulans. In this review, we will first discuss our understanding of the light response in N. crassa, about which the most is known, and will then juxtapose N. crassa with A. nidulans, which, as will be described below, provides an excellent template for understanding photosensory cross-talk. Finally, we will end with a commentary on the variability of the light response among other relevant fungi, and how our molecular understanding in the aforementioned model organisms still provides a strong base for dissecting light responses in such species.
Collapse
Affiliation(s)
- Arko Dasgupta
- Department of Genetics, Geisel School of Medicine at Dartmouth, Hanover, NH, USA
| | - Kevin K Fuller
- Department of Genetics, Geisel School of Medicine at Dartmouth, Hanover, NH, USA
| | - Jay C Dunlap
- Department of Genetics, Geisel School of Medicine at Dartmouth, Hanover, NH, USA
| | - Jennifer J Loros
- Department of Biochemistry, Geisel School of Medicine at Dartmouth, Hanover, NH, USA
| |
Collapse
|
24
|
Hurley JM, Loros JJ, Dunlap JC. The circadian system as an organizer of metabolism. Fungal Genet Biol 2015; 90:39-43. [PMID: 26498192 DOI: 10.1016/j.fgb.2015.10.002] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2015] [Revised: 10/06/2015] [Accepted: 10/16/2015] [Indexed: 10/22/2022]
Abstract
The regulation of metabolism by circadian systems is believed to be a key reason for the extensive representation of circadian rhythms within the tree of life. Despite this, surprisingly little work has focused on the link between metabolism and the clock in Neurospora, a key model system in circadian research. The analysis that has been performed has focused on the unidirectional control from the clock to metabolism and largely ignored the feedback from metabolism on the clock. Recent efforts to understand these links have broken new ground, revealing bidirectional control from the clock to metabolism and vise-versa, showing just how strongly interconnected these two cellular systems can be in fungi. This review describes both well understood and emerging links between the clock and metabolic output of fungi as well as the role that metabolism plays in influencing the rhythm set by the clock.
Collapse
Affiliation(s)
- Jennifer M Hurley
- Department of Biological Sciences, Rensselaer Polytechnic Institute, Troy, NY 12180, USA.
| | - Jennifer J Loros
- Department of Biochemistry, Geisel School of Medicine at Dartmouth, Hanover, NH 03755, USA
| | - Jay C Dunlap
- Department of Genetics, Geisel School of Medicine at Dartmouth, Hanover, NH 03755, USA
| |
Collapse
|
25
|
Dasgupta A, Chen CH, Lee C, Gladfelter AS, Dunlap JC, Loros JJ. Biological Significance of Photoreceptor Photocycle Length: VIVID Photocycle Governs the Dynamic VIVID-White Collar Complex Pool Mediating Photo-adaptation and Response to Changes in Light Intensity. PLoS Genet 2015; 11:e1005215. [PMID: 25978382 PMCID: PMC4433212 DOI: 10.1371/journal.pgen.1005215] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2015] [Accepted: 04/13/2015] [Indexed: 12/25/2022] Open
Abstract
Most organisms on earth sense light through the use of chromophore-bearing photoreceptive proteins with distinct and characteristic photocycle lengths, yet the biological significance of this adduct decay length is neither understood nor has been tested. In the filamentous fungus Neurospora crassa VIVID (VVD) is a critical player in the process of photoadaptation, the attenuation of light-induced responses and the ability to maintain photosensitivity in response to changing light intensities. Detailed in vitro analysis of the photochemistry of the blue light sensing, FAD binding, LOV domain of VVD has revealed residues around the site of photo-adduct formation that influence the stability of the adduct state (light state), that is, altering the photocycle length. We have examined the biological significance of VVD photocycle length to photoadaptation and report that a double substitution mutant (vvdI74VI85V), previously shown to have a very fast light to dark state reversion in vitro, shows significantly reduced interaction with the White Collar Complex (WCC) resulting in a substantial photoadaptation defect. This reduced interaction impacts photoreceptor transcription factor WHITE COLLAR-1 (WC-1) protein stability when N. crassa is exposed to light: The fast-reverting mutant VVD is unable to form a dynamic VVD-WCC pool of the size required for photoadaptation as assayed both by attenuation of gene expression and the ability to respond to increasing light intensity. Additionally, transcription of the clock gene frequency (frq) is sensitive to changing light intensity in a wild-type strain but not in the fast photo-reversion mutant indicating that the establishment of this dynamic VVD-WCC pool is essential in general photobiology and circadian biology. Thus, VVD photocycle length appears sculpted to establish a VVD-WCC reservoir of sufficient size to sustain photoadaptation while maintaining sensitivity to changing light intensity. The great diversity in photocycle kinetics among photoreceptors may be viewed as reflecting adaptive responses to specific and salient tasks required by organisms to respond to different photic environments.
Collapse
Affiliation(s)
- Arko Dasgupta
- Department of Genetics, Geisel School of Medicine, Dartmouth, Hanover, New Hampshire, United States of America
| | - Chen-Hui Chen
- Department of Genetics, Geisel School of Medicine, Dartmouth, Hanover, New Hampshire, United States of America
| | - ChangHwan Lee
- Department of Biological Sciences, Dartmouth, Hanover, New Hampshire, United States of America
| | - Amy S. Gladfelter
- Department of Biological Sciences, Dartmouth, Hanover, New Hampshire, United States of America
| | - Jay C. Dunlap
- Department of Genetics, Geisel School of Medicine, Dartmouth, Hanover, New Hampshire, United States of America
| | - Jennifer J. Loros
- Department of Genetics, Geisel School of Medicine, Dartmouth, Hanover, New Hampshire, United States of America
- Department of Biochemistry, Geisel School of Medicine, Dartmouth, Hanover, New Hampshire, United States of America
- * E-mail:
| |
Collapse
|
26
|
Oliveira AG, Stevani CV, Waldenmaier HE, Viviani V, Emerson JM, Loros JJ, Dunlap JC. Circadian control sheds light on fungal bioluminescence. Curr Biol 2015; 25:964-8. [PMID: 25802150 DOI: 10.1016/j.cub.2015.02.021] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2014] [Revised: 01/30/2015] [Accepted: 02/03/2015] [Indexed: 10/23/2022]
Abstract
Bioluminescence, the creation and emission of light by organisms, affords insight into the lives of organisms doing it. Luminous living things are widespread and access diverse mechanisms to generate and control luminescence [1-5]. Among the least studied bioluminescent organisms are phylogenetically rare fungi-only 71 species, all within the ∼ 9,000 fungi of the temperate and tropical Agaricales order-are reported from among ∼ 100,000 described fungal species [6, 7]. All require oxygen [8] and energy (NADH or NADPH) for bioluminescence and are reported to emit green light (λmax 530 nm) continuously, implying a metabolic function for bioluminescence, perhaps as a byproduct of oxidative metabolism in lignin degradation. Here, however, we report that bioluminescence from the mycelium of Neonothopanus gardneri is controlled by a temperature-compensated circadian clock, the result of cycles in content/activity of the luciferase, reductase, and luciferin that comprise the luminescent system. Because regulation implies an adaptive function for bioluminescence, a controversial question for more than two millennia [8-15], we examined interactions between luminescent fungi and insects [16]. Prosthetic acrylic resin "mushrooms," internally illuminated by a green LED emitting light similar to the bioluminescence, attract staphilinid rove beetles (coleopterans), as well as hemipterans (true bugs), dipterans (flies), and hymenopterans (wasps and ants), at numbers far greater than dark control traps. Thus, circadian control may optimize energy use for when bioluminescence is most visible, attracting insects that can in turn help in spore dispersal, thereby benefitting fungi growing under the forest canopy, where wind flow is greatly reduced.
Collapse
Affiliation(s)
- Anderson G Oliveira
- Departamento de Oceanografia Física, Química, e Geológica, Instituto Oceanográfico, Universidade de São Paulo, São Paulo, SP 05508-120, Brazil
| | - Cassius V Stevani
- Departamento de Química Fundamental, Instituto de Química, Universidade de São Paulo, São Paulo, SP 05508-000, Brazil.
| | - Hans E Waldenmaier
- Departamento de Química Fundamental, Instituto de Química, Universidade de São Paulo, São Paulo, SP 05508-000, Brazil; Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, São Paulo, SP 05508-000, Brazil
| | - Vadim Viviani
- Departamento de Bioquímica, Universidade Federal de São Carlos, Campus Sorocoba, Rodovia João Leme dos Santos, km 110, Sorocaba, SP 18052-780, Brazil
| | - Jillian M Emerson
- Department of Biochemistry, Geisel School of Medicine at Dartmouth, Hanover, NH 03755, USA
| | - Jennifer J Loros
- Department of Biochemistry, Geisel School of Medicine at Dartmouth, Hanover, NH 03755, USA
| | - Jay C Dunlap
- Department of Genetics, Geisel School of Medicine at Dartmouth, Hanover, NH 03755, USA.
| |
Collapse
|
27
|
Larrondo LF, Olivares-Yañez C, Baker CL, Loros JJ, Dunlap JC. Circadian rhythms. Decoupling circadian clock protein turnover from circadian period determination. Science 2015; 347:1257277. [PMID: 25635104 DOI: 10.1126/science.1257277] [Citation(s) in RCA: 113] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
The mechanistic basis of eukaryotic circadian oscillators in model systems as diverse as Neurospora, Drosophila, and mammalian cells is thought to be a transcription-and-translation-based negative feedback loop, wherein progressive and controlled phosphorylation of one or more negative elements ultimately elicits their own proteasome-mediated degradation, thereby releasing negative feedback and determining circadian period length. The Neurospora crassa circadian negative element FREQUENCY (FRQ) exemplifies such proteins; it is progressively phosphorylated at more than 100 sites, and strains bearing alleles of frq with anomalous phosphorylation display abnormal stability of FRQ that is well correlated with altered periods or apparent arrhythmicity. Unexpectedly, we unveiled normal circadian oscillations that reflect the allelic state of frq but that persist in the absence of typical degradation of FRQ. This manifest uncoupling of negative element turnover from circadian period length determination is not consistent with the consensus eukaryotic circadian model.
Collapse
Affiliation(s)
- Luis F Larrondo
- Millennium Nucleus for Fungal Integrative and Synthetic Biology, Departamento de Genética Molecular y Microbiología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Casilla 114-D, Santiago, Chile. Department of Genetics, Geisel School of Medicine at Dartmouth, Hanover, NH 03755, USA.
| | - Consuelo Olivares-Yañez
- Millennium Nucleus for Fungal Integrative and Synthetic Biology, Departamento de Genética Molecular y Microbiología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Casilla 114-D, Santiago, Chile
| | - Christopher L Baker
- Department of Genetics, Geisel School of Medicine at Dartmouth, Hanover, NH 03755, USA
| | - Jennifer J Loros
- Department of Genetics, Geisel School of Medicine at Dartmouth, Hanover, NH 03755, USA. Department of Biochemistry, Geisel School of Medicine at Dartmouth, Hanover, NH 03755, USA
| | - Jay C Dunlap
- Department of Genetics, Geisel School of Medicine at Dartmouth, Hanover, NH 03755, USA.
| |
Collapse
|
28
|
Abstract
The circadian clock exists to synchronize inner physiology with the external world, allowing life to anticipate and adapt to the continual changes that occur in an organism's environment. The clock architecture is highly conserved, present in almost all major branches of life. Within eukaryotes, the filamentous fungus Neurospora crassa has consistently been used as an excellent model organism to uncover the basic circadian physiology and molecular biology. The Neurospora model has elucidated our fundamental understanding of the clock as nested positive and negative feedback loop, regulated by transcriptional and posttranscriptional processes. This review will examine the basics of circadian rhythms in the model filamentous fungus N. crassa as well as highlight the output of the clock in Neurospora and the reasons that N. crassa has continued to be a strong model for the study of circadian rhythms. It will also synopsize classical and emerging methods in the study of the circadian clock.
Collapse
Affiliation(s)
- Jennifer Hurley
- Department of Genetics, Geisel School of Medicine at Dartmouth, Hanover, New Hampshire, USA
| | - Jennifer J Loros
- Department of Genetics, Geisel School of Medicine at Dartmouth, Hanover, New Hampshire, USA; Department of Biochemistry, Geisel School of Medicine at Dartmouth, Hanover, New Hampshire, USA
| | - Jay C Dunlap
- Department of Genetics, Geisel School of Medicine at Dartmouth, Hanover, New Hampshire, USA.
| |
Collapse
|
29
|
Abstract
Investigation of the red bread mold that contaminated French bakeries nearly two centuries ago has led to a wealth of discoveries that have impacted our understanding of genetic, biochemical, and molecular mechanisms in microbes, from Mendelian genetics and the gene-enzyme relationship to circadian rhythm and plant cell wall degradation. Early Neurospora research focused on elucidating mechanisms of genetic recombination and gene action and later progressed to addressing complex biological questions of eukaryotic microbes. Here we review the evolution of the filamentous fungus Neurospora as a model microbe over the past century. We discuss the origins of Neurospora as a model microbe, the immediate scientific impacts from work in this filamentous fungus, and how the introduction of other model organisms (i.e., Escherichia coli and Saccharomyces cerevisiae) redirected the focus of Neurospora research. Neurospora has and continues to inform our understanding of a myriad of basic scientific concepts and now has the opportunity to forge into the applied biosciences and biotechnology.
Collapse
Affiliation(s)
- Christine M Roche
- Chemical and Biomolecular Engineering Department, University of California, Berkeley, California USA Energy Biosciences Institute, University of California, Berkeley, California USA
| | - Jennifer J Loros
- Department of Genetics, Geisel School of Medicine at Dartmouth, Hanover, New Hampshire USA Department of Biochemistry, Geisel School of Medicine at Dartmouth, Hanover, New Hampshire USA
| | - Kevin McCluskey
- Fungal Genetics Stock Center, Department of Plant Pathology, Kansas State University, Manhattan, Kansas USA
| | - N Louise Glass
- Energy Biosciences Institute, University of California, Berkeley, California USA Plant and Microbial Biology Department, University of California, Berkeley, California USA
| |
Collapse
|
30
|
Fuller KK, Loros JJ, Dunlap JC. Fungal photobiology: visible light as a signal for stress, space and time. Curr Genet 2014; 61:275-88. [PMID: 25323429 DOI: 10.1007/s00294-014-0451-0] [Citation(s) in RCA: 91] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2014] [Revised: 08/25/2014] [Accepted: 08/29/2014] [Indexed: 12/25/2022]
Abstract
Visible light is an important source of energy and information for much of life on this planet. Though fungi are neither photosynthetic nor capable of observing adjacent objects, it is estimated that the majority of fungal species display some form of light response, ranging from developmental decision-making to metabolic reprogramming to pathogenesis. As such, advances in our understanding of fungal photobiology will likely reach the broad fields impacted by these organisms, including agriculture, industry and medicine. In this review, we will first describe the mechanisms by which fungi sense light and then discuss the selective advantages likely imparted by their ability to do so.
Collapse
Affiliation(s)
- Kevin K Fuller
- Department of Genetics, Geisel School of Medicine at Dartmouth, Hanover, NH, 03755, USA,
| | | | | |
Collapse
|
31
|
Gooch VD, Johnson AE, Bourne BJ, Nix BT, Maas JA, Fox JA, Loros JJ, Larrondo LF, Dunlap JC. A kinetic study of the effects of light on circadian rhythmicity of the frq promoter of Neurospora crassa. J Biol Rhythms 2014; 29:38-48. [PMID: 24492881 DOI: 10.1177/0748730413517981] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
The role of the frq gene in the Neurospora crassa circadian rhythm has been widely studied, but technical limitations have hindered a thorough analysis of frq circadian expression waveform. Through our experiments, we have shown an improved precision in defining Neurospora's circadian rhythm kinetics using a codon optimized firefly luciferase gene reporter linked to a frq promoter. In vivo examination of this real-time reporter has allowed for a better understanding of the relationship of the light responsive elements of the frq promoter to its circadian feedback components. We provide a detailed phase response curve showing the phase shifts induced by a light pulse applied at different points of the circadian cycle. Using the frq-luc reporter, we have found that a 12-h light:12-h dark cycle (12L:12D) results in a luciferase expression waveform that is more complex and higher in amplitude than that seen in free-running conditions of constant darkness (DD). When using a lighting regime more consistent with solar timing, rather than a square wave pattern, one observes a circadian waveform that is smoother, lower in amplitude, and different in phasing. Using dim light in place of darkness in these experiments also affects the resulting waveform and phasing. Our experiments illustrate Neurospora's circadian kinetics in greater detail than previous methods, providing further insight into the complex underlying biochemical, genetic, and physiological mechanisms underpinning the circadian oscillator.
Collapse
Affiliation(s)
- Van D Gooch
- Division of Science and Mathematics, University of Minnesota-Morris, Morris, MN, USA
| | | | | | | | | | | | | | | | | |
Collapse
|
32
|
Abstract
The fungus Neurospora crassa constitutes an important model system extensively used in chronobiology. Several studies have addressed how environmental cues, such as light, can reset or synchronize a circadian system. By means of an optimized firefly luciferase reporter gene and a controllable lighting system, we show that Neurospora can display molecular circadian rhythms in dim light when cultures receive bright light prior to entering dim light conditions. We refer to this behavior as the "bright to dim oscillatory response" (BDOR). The bright light treatment can be applied up to 76 h prior to dim exposure, and it can be as short as 15 min in duration. We have characterized this response in respect to the duration of the light pulse, the time of the light pulse before dim, the intensity of dim light, and the oscillation dynamics in dim light. Although the molecular mechanism that drives the BDOR remains obscure, these findings suggest that a long-term memory of bright light exists as part of the circadian molecular components. It is important to consider the ecological significance of such dim light responses in respect to how organisms naturally maintain their timing mechanism in moonlight.
Collapse
Affiliation(s)
- Van D Gooch
- Division of Science and Mathematics, University of Minnesota-Morris, Morris, MN, USA
| | | | | | | | | |
Collapse
|
33
|
Wang B, Kettenbach AN, Gerber SA, Loros JJ, Dunlap JC. Neurospora WC-1 recruits SWI/SNF to remodel frequency and initiate a circadian cycle. PLoS Genet 2014; 10:e1004599. [PMID: 25254987 PMCID: PMC4177678 DOI: 10.1371/journal.pgen.1004599] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2013] [Accepted: 07/13/2014] [Indexed: 12/23/2022] Open
Abstract
In the negative feedback loop comprising the Neurospora circadian oscillator, the White Collar Complex (WCC) formed from White Collar-1 (WC-1) and White Collar-2 (WC-2) drives transcription of the circadian pacemaker gene frequency (frq). Although FRQ-dependent repression of WCC has been extensively studied, the mechanism by which the WCC initiates a circadian cycle remains elusive. Structure/function analysis of WC-1 eliminated domains previously thought to transactivate frq expression but instead identified amino acids 100–200 as essential for frq circadian expression. A proteomics-based search for coactivators with WCC uncovered the SWI/SNF (SWItch/Sucrose NonFermentable) complex: SWI/SNF interacts with WCC in vivo and in vitro, binds to the Clock box in the frq promoter, and is required both for circadian remodeling of nucleosomes at frq and for rhythmic frq expression; interestingly, SWI/SNF is not required for light-induced frq expression. These data suggest a model in which WC-1 recruits SWI/SNF to remodel and loop chromatin at frq, thereby activating frq expression to initiate the circadian cycle. Circadian clocks govern behavior in a wide variety of organisms. These clocks are assembled in such a way that proteins encoded by a few dedicated “clock genes” form a complex that acts to reduce their own expression. That is, the genes and proteins participate in a negative feedback loop, and so long as the feedback has delays built in, this system will oscillate. The feedback loops that underlie circadian rhythms in fungi and animals are quite similar in many ways, and while much is known about the proteins themselves, both those that activate the dedicated clock genes and the clock proteins that repress their own expression, relatively little is known about how the initial expression of the clock genes is activated. In Neurospora, a fungal model for these clocks, the proteins that activate expression of the clock gene “frequency” bind to DNA far away from where the coding part of the gene begins, and a mystery has been how this action-at-a-distance works. The answer revealed here is that the activating proteins recruit other proteins to unwrap the DNA and bring the distal site close to the place where the coding part of the gene begins.
Collapse
Affiliation(s)
- Bin Wang
- Department of Genetics, Geisel School of Medicine, Dartmouth, Hanover, New Hampshire, United States of America
| | - Arminja N. Kettenbach
- Department of Genetics, Geisel School of Medicine, Dartmouth, Hanover, New Hampshire, United States of America
- Norris Cotton Cancer Center, Geisel School of Medicine, Dartmouth, Hanover, New Hampshire, United States of America
| | - Scott A. Gerber
- Department of Genetics, Geisel School of Medicine, Dartmouth, Hanover, New Hampshire, United States of America
- Norris Cotton Cancer Center, Geisel School of Medicine, Dartmouth, Hanover, New Hampshire, United States of America
| | - Jennifer J. Loros
- Department of Genetics, Geisel School of Medicine, Dartmouth, Hanover, New Hampshire, United States of America
- Department of Biochemistry, Geisel School of Medicine, Dartmouth, Hanover, New Hampshire, United States of America
| | - Jay C. Dunlap
- Department of Genetics, Geisel School of Medicine, Dartmouth, Hanover, New Hampshire, United States of America
- * E-mail:
| |
Collapse
|
34
|
Hurley JM, Larrondo LF, Loros JJ, Dunlap JC. Conserved RNA helicase FRH acts nonenzymatically to support the intrinsically disordered neurospora clock protein FRQ. Mol Cell 2013; 52:832-43. [PMID: 24316221 DOI: 10.1016/j.molcel.2013.11.005] [Citation(s) in RCA: 67] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2013] [Revised: 10/08/2013] [Accepted: 10/31/2013] [Indexed: 11/24/2022]
Abstract
Protein conformation dictates a great deal of protein function. A class of naturally unstructured proteins, termed intrinsically disordered proteins (IDPs), demonstrates that flexibility in structure can be as important mechanistically as rigid structure. At the core of the circadian transcription/translation feedback loop in Neurospora crassa is the protein FREQUENCY (FRQ), shown here shown to share many characteristics of IDPs. FRQ in turn binds to FREQUENCY-Interacting RNA Helicase (FRH), whose clock function has been assumed to relate to its predicted helicase function. However, mutational analyses reveal that the helicase function of FRH is not essential for the clock, and a region of FRH distinct from the helicase region is essential for stabilizing FRQ against rapid degradation via a pathway distinct from its typical ubiquitin-mediated turnover. These data lead to the hypothesis that FRQ is an IDP and that FRH acts nonenzymatically, stabilizing FRQ to enable proper clock circuitry/function.
Collapse
Affiliation(s)
- Jennifer M Hurley
- Department of Genetics, Geisel School of Medicine at Dartmouth, Hanover, NH 03755, USA
| | - Luis F Larrondo
- Departamento de Genética Molecular y Microbiología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Alameda 340, Santiago, Chile
| | - Jennifer J Loros
- Department of Genetics, Geisel School of Medicine at Dartmouth, Hanover, NH 03755, USA; Department of Biochemistry, Geisel School of Medicine at Dartmouth, Hanover, NH 03755, USA
| | - Jay C Dunlap
- Department of Genetics, Geisel School of Medicine at Dartmouth, Hanover, NH 03755, USA.
| |
Collapse
|
35
|
Gamsby JJ, Templeton EL, Bonvini LA, Wang W, Loros JJ, Dunlap JC, Green AI, Gulick D. The circadian Per1 and Per2 genes influence alcohol intake, reinforcement, and blood alcohol levels. Behav Brain Res 2013; 249:15-21. [PMID: 23608482 DOI: 10.1016/j.bbr.2013.04.016] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2013] [Revised: 04/09/2013] [Accepted: 04/13/2013] [Indexed: 11/26/2022]
Abstract
BACKGROUND Perturbations in the function of core circadian clock components such as the Period (Per) family of genes are associated with alcohol use disorder, and disruptions in circadian cycles may contribute to alcohol abuse and relapse. This study tested ethanol consumption, reinforcement, and metabolism in mice containing functional mutations in Per1 and/or Per2 genes on an ethanol-preferring background, C57BL/6J mice. METHODS Mice were tested in: (A) free-access intake with ascending concentrations of ethanol (2-16%, v/v), (B) conditioned place preference using ethanol (2g/kg for males; 2.5g/kg for females) vs. saline injections, (C) recovery of the righting reflex following a 4g/kg bolus of ethanol, and (D) blood ethanol levels 1h after a 2g/kg bolus of ethanol. RESULTS All Per mutant (mPer) mice showed increased ethanol intake and condition place preference compared to controls. There were also genotypic differences in blood ethanol concentration: in males, only mPer1 mice showed a significantly higher blood ethanol concentration than WT mice, but in females, all mPer mice showed higher blood ethanol levels than WT mice. CONCLUSIONS Mutation of either Per1 or Per2, as well as mutations of both genes, increases ethanol intake and reinforcement in an ethanol-preferring mouse model. In addition, this increase in ethanol seeking behavior seems to result both from a change in ethanol metabolism and a change in reward responding to ethanol, but not from any change in sensitivity to ethanol's sedating effects.
Collapse
Affiliation(s)
- J J Gamsby
- Department of Genetics, Geisel School of Medicine at Dartmouth, United States
| | | | | | | | | | | | | | | |
Collapse
|
36
|
Grant GD, Gamsby J, Martyanov V, Brooks L, George LK, Mahoney JM, Loros JJ, Dunlap JC, Whitfield ML. Live-cell monitoring of periodic gene expression in synchronous human cells identifies Forkhead genes involved in cell cycle control. Mol Biol Cell 2012; 23:3079-93. [PMID: 22740631 PMCID: PMC3418304 DOI: 10.1091/mbc.e11-02-0170] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
A periodic luciferase reporter system from cell cycle–regulated promoters in synchronous U2OS cells measures periodic, cell cycle–regulated gene expression in live cells. This assay is used to identify Forkhead transcription factors that control periodic gene expression, and it identifies FOXK1 as an activator of key cell cycle genes. We developed a system to monitor periodic luciferase activity from cell cycle–regulated promoters in synchronous cells. Reporters were driven by a minimal human E2F1 promoter with peak expression in G1/S or a basal promoter with six Forkhead DNA-binding sites with peak expression at G2/M. After cell cycle synchronization, luciferase activity was measured in live cells at 10-min intervals across three to four synchronous cell cycles, allowing unprecedented resolution of cell cycle–regulated gene expression. We used this assay to screen Forkhead transcription factors for control of periodic gene expression. We confirmed a role for FOXM1 and identified two novel cell cycle regulators, FOXJ3 and FOXK1. Knockdown of FOXJ3 and FOXK1 eliminated cell cycle–dependent oscillations and resulted in decreased cell proliferation rates. Analysis of genes regulated by FOXJ3 and FOXK1 showed that FOXJ3 may regulate a network of zinc finger proteins and that FOXK1 binds to the promoter and regulates DHFR, TYMS, GSDMD, and the E2F binding partner TFDP1. Chromatin immunoprecipitation followed by high-throughput sequencing analysis identified 4329 genomic loci bound by FOXK1, 83% of which contained a FOXK1-binding motif. We verified that a subset of these loci are activated by wild-type FOXK1 but not by a FOXK1 (H355A) DNA-binding mutant.
Collapse
Affiliation(s)
- Gavin D Grant
- Department of Genetics, Geisel School of Medicine at Dartmouth, Hanover, NH 03755, USA
| | | | | | | | | | | | | | | | | |
Collapse
|
37
|
Larrondo LF, Loros JJ, Dunlap JC. High-resolution spatiotemporal analysis of gene expression in real time: in vivo analysis of circadian rhythms in Neurospora crassa using a FREQUENCY-luciferase translational reporter. Fungal Genet Biol 2012; 49:681-3. [PMID: 22695169 DOI: 10.1016/j.fgb.2012.06.001] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2012] [Revised: 05/22/2012] [Accepted: 06/01/2012] [Indexed: 11/30/2022]
Abstract
The pacemaker of the Neurospora circadian clock is composed of a transcriptional-translational feedback loop that has been intensively studied during the last two decades. Invaluable information has been derived from measuring the expression of the central clock component frequency (frq) under liquid culture conditions. Direct analyses of frq mRNA and protein levels on solid media - where overt circadian rhythms are normally visualized - have not been trivial due to technical issues. Nevertheless, a frq promoter-luciferase reporter has recently allowed the study of frq transcription under these conditions. It is known that FRQ undergoes extensive posttranslational modifications, and changes in its levels provide important information regarding the clockworks. Here we describe a FRQ-luciferase translational fusion reporter that directly tracks FRQ levels, granting access to a better understanding and analysis of FRQ dynamics in vivo. More generally the method, which allows the investigator to follow continuous gene expression in real time in a spatially and temporally unrestricted manner, should be widely applicable to analyses of environmentally and developmentally regulated gene expression in ascomycete filamentous fungi as well as in basidiomycetes.
Collapse
Affiliation(s)
- Luis F Larrondo
- Departamento de Genética Molecular y Microbiología, Pontificia Universidad Católica de Chile, Santiago, Chile.
| | | | | |
Collapse
|
38
|
Abstract
Light, oxygen, or voltage (LOV) protein domains are present in many signaling proteins in bacteria, archaea, protists, plants, and fungi. The LOV protein VIVID (VVD) of the filamentous fungus Neurospora crassa enables the organism to adapt to constant or increasing amounts of light and facilitates proper entrainment of circadian rhythms. Here, we determined the crystal structure of the fully light-adapted VVD dimer and reveal the mechanism by which light-driven conformational change alters the oligomeric state of the protein. Light-induced formation of a cysteinyl-flavin adduct generated a new hydrogen bond network that released the amino (N) terminus from the protein core and restructured an acceptor pocket for binding of the N terminus on the opposite subunit of the dimer. Substitution of residues critical for the switch between the monomeric and the dimeric states of the protein had profound effects on light adaptation in Neurospora. The mechanism of dimerization of VVD provides molecular details that explain how members of a large family of photoreceptors convert light responses to alterations in protein-protein interactions.
Collapse
Affiliation(s)
- Anand T Vaidya
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY 14853, USA
| | | | | | | | | |
Collapse
|
39
|
Abstract
Circadian clocks organize our inner physiology with respect to the external world, providing life with the ability to anticipate and thereby better prepare for major fluctuations in its environment. Circadian systems are widely represented in nearly all major branches of life, except archaebacteria, and within the eukaryotes, the filamentous fungus Neurospora crassa has served for nearly half a century as a durable model organism for uncovering the basic circadian physiology and molecular biology. Studies using Neurospora have clarified our fundamental understanding of the clock as nested positive and negative feedback loops regulated through transcriptional and post-transcriptional processes. These feedback loops are centered on a limited number of proteins that form molecular complexes, and their regulation provides a physical explanation for nearly all clock properties. This review will introduce the basics of circadian rhythms, the model filamentous fungus N. crassa, and provide an overview of the molecular components and regulation of the circadian clock.
Collapse
|
40
|
Belden WJ, Lewis ZA, Selker EU, Loros JJ, Dunlap JC. CHD1 remodels chromatin and influences transient DNA methylation at the clock gene frequency. PLoS Genet 2011; 7:e1002166. [PMID: 21811413 PMCID: PMC3140994 DOI: 10.1371/journal.pgen.1002166] [Citation(s) in RCA: 78] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2011] [Accepted: 05/18/2011] [Indexed: 12/21/2022] Open
Abstract
Circadian-regulated gene expression is predominantly controlled by a transcriptional negative feedback loop, and it is evident that chromatin modifications and chromatin remodeling are integral to this process in eukaryotes. We previously determined that multiple ATP-dependent chromatin-remodeling enzymes function at frequency (frq). In this report, we demonstrate that the Neurospora homologue of chd1 is required for normal remodeling of chromatin at frq and is required for normal frq expression and sustained rhythmicity. Surprisingly, our studies of CHD1 also revealed that DNA sequences within the frq promoter are methylated, and deletion of chd1 results in expansion of this methylated domain. DNA methylation of the frq locus is altered in strains bearing mutations in a variety of circadian clock genes, including frq, frh, wc-1, and the gene encoding the frq antisense transcript (qrf). Furthermore, frq methylation depends on the DNA methyltransferase, DIM-2. Phenotypic characterization of Δdim-2 strains revealed an approximate WT period length and a phase advance of approximately 2 hours, indicating that methylation plays only an ancillary role in clock-regulated gene expression. This suggests that DNA methylation, like the antisense transcript, is necessary to establish proper clock phasing but does not control overt rhythmicity. These data demonstrate that the epigenetic state of clock genes is dependent on normal regulation of clock components.
Collapse
Affiliation(s)
- William J. Belden
- Department of Genetics, Dartmouth Medical School, Hanover, New Hampshire, United States of America
- Department of Biochemistry and Microbiology, Rutgers, The State University of New Jersey, New Brunswick, New Jersey, United States of America
| | - Zachary A. Lewis
- Institute of Molecular Biology, University of Oregon, Eugene, Oregon, United States of America
| | - Eric U. Selker
- Institute of Molecular Biology, University of Oregon, Eugene, Oregon, United States of America
| | - Jennifer J. Loros
- Department of Genetics, Dartmouth Medical School, Hanover, New Hampshire, United States of America
- Department of Biochemistry, Dartmouth Medical School, Hanover, New Hampshire, United States of America
| | - Jay C. Dunlap
- Department of Genetics, Dartmouth Medical School, Hanover, New Hampshire, United States of America
- * E-mail:
| |
Collapse
|
41
|
Poliandri AHB, Gamsby JJ, Christian M, Spinella MJ, Loros JJ, Dunlap JC, Parker MG. Modulation of clock gene expression by the transcriptional coregulator receptor interacting protein 140 (RIP140). J Biol Rhythms 2011; 26:187-99. [PMID: 21628546 PMCID: PMC3207295 DOI: 10.1177/0748730411401579] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Circadian rhythms are generated in central and peripheral tissues by an intracellular oscillating timing mechanism known as the circadian clock. Several lines of evidence show a strong and bidirectional interplay between metabolism and circadian rhythms. Receptor interacting protein 140 (RIP140) is a coregulator for nuclear receptors and other transcription factors that represses catabolic pathways in metabolic tissues. Although RIP140 functions as a corepressor for most nuclear receptors, mounting evidence points to RIP140 as a dual coregulator that can repress or activate different sets of genes. Here, we demonstrate that RIP140 mRNA and protein levels are under circadian regulation and identify RIP140 as a modulator of clock gene expression, suggesting that RIP140 can participate in a feedback mechanism affecting the circadian clock. We show that the absence of RIP140 disturbs the basal levels of BMAL1 and other clock genes, reducing the amplitude of their oscillations. In addition, we demonstrate that RIP140 is recruited to retinoid-related orphan receptor (ROR) binding sites on the BMAL1 promoter, directly interacts with RORα, and increases transcription from the BMAL1 promoter in a RORα-dependent manner. These results indicate that RIP140 is not only involved in metabolic control but also acts as a coactivator for RORα, influencing clock gene expression.
Collapse
Affiliation(s)
- Ariel H. B. Poliandri
- Institute of Reproductive and
Developmental Biology, Faculty of Medicine, Imperial College London, London, United
Kingdom
| | - Joshua J. Gamsby
- Department of Genetics,
Dartmouth Medical School, Dartmouth Hitchcock Medical Center, Hanover, NH, USA
| | - Mark Christian
- Institute of Reproductive and
Developmental Biology, Faculty of Medicine, Imperial College London, London, United
Kingdom
| | - Michael J. Spinella
- Department of Pharmacology and
Toxicology, Dartmouth Medical School, Dartmouth Hitchcock Medical Center, Hanover,
NH, USA
| | - Jennifer J. Loros
- Department of Genetics,
Dartmouth Medical School, Dartmouth Hitchcock Medical Center, Hanover, NH, USA
| | - Jay C. Dunlap
- Department of Genetics,
Dartmouth Medical School, Dartmouth Hitchcock Medical Center, Hanover, NH, USA
| | - Malcolm G. Parker
- Institute of Reproductive and
Developmental Biology, Faculty of Medicine, Imperial College London, London, United
Kingdom
| |
Collapse
|
42
|
Abstract
Light not only is indispensable as an energy source for life on earth but also serves as an essential environmental cue conveying the information of daily and seasonal time to organisms across different kingdoms. Although the molecular mechanisms underlying light responses are actively explored in various light-sensitive organisms, these studies are either hindered by the complexity of the systems or an incomplete familiarity with the light signaling components involved in the scheme. Therefore, study of a simple and well-characterized model system is desirable to expand our knowledge of basic properties underlying the regulation of biological light responses. This review will briefly introduce the basic light sensing machinery in Neurospora crassa, a filamentous fungus, and then focus on the most recent advances in employing Neurospora as a model to study light signaling cascades, photoadaptation, and circadian clock-modulated effects in eukaryotic cells. Also, we will summarize the functions of a number of putative photoreceptors in Neurospora, and discuss the implications of the study of Neurospora to the field of fungal photobiology and some challenges for future studies.
Collapse
Affiliation(s)
- Chen-Hui Chen
- Department of Genetics, Dartmouth Medical School, Hanover, NH 03755
| | - Jay C. Dunlap
- Department of Genetics, Dartmouth Medical School, Hanover, NH 03755
| | - Jennifer J. Loros
- Department of Biochemistry, Dartmouth Medical School, Hanover, NH 03755
| |
Collapse
|
43
|
Chen CH, Loros JJ. Neurospora sees the light: light signaling components in a model system. Commun Integr Biol 2010; 2:448-51. [PMID: 19907715 DOI: 10.4161/cib.2.5.8835] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2009] [Accepted: 04/24/2009] [Indexed: 12/29/2022] Open
Abstract
Light is a key environmental signal for most life on earth. Over 5% of Neurospora crassa genes are expressed in response to light stimulation in a temporally regulated cascade that includes several transcription factors. Fungal genomes, including Neurospora's, may encode several different proteins capable of binding chromophores with the ability to harvest light energy as well as proteins that can interact with primary photoreceptors or further propogate the light signal. The best understood photo- receptors are the evolutionarily conserved White Collar proteins, and the related Vivid protein, but fungi may also encode phytochromes, cryptochromes and opsins.
Collapse
Affiliation(s)
- Chen-Hui Chen
- Department of Genetics, Dartmouth Medical School, Hanover, NH, USA
| | | |
Collapse
|
44
|
Heim KC, Gamsby JJ, Hever MP, Freemantle SJ, Loros JJ, Dunlap JC, Spinella MJ. Retinoic acid mediates long-paced oscillations in retinoid receptor activity: evidence for a potential role for RIP140. PLoS One 2009; 4:e7639. [PMID: 19862326 PMCID: PMC2763268 DOI: 10.1371/journal.pone.0007639] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2009] [Accepted: 10/08/2009] [Indexed: 11/20/2022] Open
Abstract
Background Mechanisms that underlie oscillatory transcriptional activity of nuclear receptors (NRs) are incompletely understood. Evidence exists for rapid, cyclic recruitment of coregulatory complexes upon activation of nuclear receptors. RIP140 is a NR coregulator that represses the transactivation of agonist-bound nuclear receptors. Previously, we showed that RIP140 is inducible by all-trans retinoic acid (RA) and mediates limiting, negative-feedback regulation of retinoid signaling. Methodology and Findings Here we report that in the continued presence of RA, long-paced oscillations of retinoic acid receptor (RAR) activity occur with a period ranging from 24 to 35 hours. Endogenous expression of RIP140 and other RA-target genes also oscillate in the presence of RA. Cyclic retinoid receptor transactivation is ablated by constitutive overexpression of RIP140. Further, depletion of RIP140 disrupts cyclic expression of the RA target gene HOXA5. Evidence is provided that RIP140 may limit RAR signaling in a selective, non-redundant manner in contrast to the classic NR coregulators NCoR1 and SRC1 that are not RA-inducible, do not cycle, and may be partially redundant in limiting RAR activity. Finally, evidence is provided that RIP140 can repress and be induced by other nuclear receptors in a manner that suggests potential participation in other NR oscillations. Conclusions and Significance We provide evidence for novel, long-paced oscillatory retinoid receptor activity and hypothesize that this may be paced in part, by RIP140. Oscillatory NR activity may be involved in mediating hormone actions of physiological and pathological importance.
Collapse
Affiliation(s)
- Kelly C. Heim
- Department of Pharmacology and Toxicology, Hanover, New Hampshire, United States of America
| | - Joshua J. Gamsby
- Department of Genetics, Dartmouth Medical School, Hanover, New Hampshire, United States of America
| | - Mary P. Hever
- Department of Pharmacology and Toxicology, Hanover, New Hampshire, United States of America
| | - Sarah J. Freemantle
- Department of Pharmacology and Toxicology, Hanover, New Hampshire, United States of America
| | - Jennifer J. Loros
- Department of Genetics, Dartmouth Medical School, Hanover, New Hampshire, United States of America
| | - Jay C. Dunlap
- Department of Genetics, Dartmouth Medical School, Hanover, New Hampshire, United States of America
| | - Michael J. Spinella
- Department of Pharmacology and Toxicology, Hanover, New Hampshire, United States of America
- Norris Cotton Cancer Center, Dartmouth Hitchcock Medical Center, Hanover, New Hampshire, United States of America
- * E-mail:
| |
Collapse
|
45
|
Mehra A, Baker CL, Loros JJ, Dunlap JC. Post-translational modifications in circadian rhythms. Trends Biochem Sci 2009; 34:483-90. [PMID: 19740663 DOI: 10.1016/j.tibs.2009.06.006] [Citation(s) in RCA: 144] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2009] [Revised: 06/02/2009] [Accepted: 06/02/2009] [Indexed: 11/20/2022]
Abstract
The pace has quickened in circadian biology research. In particular, an abundance of results focused on post-translational modifications (PTMs) is sharpening our view of circadian molecular clockworks. PTMs affect nearly all aspects of clock biology; in some cases they are essential for clock function and in others, they provide layers of regulatory fine-tuning. Our goal is to review recent advances in clock PTMs, help make sense of emerging themes, and spotlight intriguing (and perhaps controversial) new findings. We focus on PTMs affecting the core functions of eukaryotic clocks, in particular the functionally related oscillators in Neurospora crassa, Drosophila melanogaster, and mammalian cells.
Collapse
Affiliation(s)
- Arun Mehra
- Department of Genetics, Dartmouth Medical School, Hanover, NH 03755, USA
| | | | | | | |
Collapse
|
46
|
Baker CL, Kettenbach AN, Loros JJ, Gerber SA, Dunlap JC. Quantitative proteomics reveals a dynamic interactome and phase-specific phosphorylation in the Neurospora circadian clock. Mol Cell 2009; 34:354-63. [PMID: 19450533 DOI: 10.1016/j.molcel.2009.04.023] [Citation(s) in RCA: 119] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2008] [Revised: 02/24/2009] [Accepted: 04/17/2009] [Indexed: 10/20/2022]
Abstract
Circadian systems are comprised of multiple proteins functioning together to produce feedback loops driving robust, approximately 24 hr rhythms. In all circadian systems, proteins in these loops are regulated through myriad physically and temporally distinct posttranslational modifications (PTMs). To better understand how PTMs impact a circadian oscillator, we implemented a proteomics-based approach by combining purification of endogenous FREQUENCY (FRQ) and its interacting partners with quantitative mass spectrometry (MS). We identify and quantify time-of-day-specific protein-protein interactions in the clock and show how these provide a platform for temporal and physical separation between the dual roles of FRQ. Additionally, by unambiguously identifying over 75 phosphorylated residues, following their quantitative change over a circadian cycle, and examining the phenotypes of strains that have lost these sites, we demonstrate how spatially and temporally regulated phosphorylation has opposing effects directly on overt circadian rhythms and FRQ stability.
Collapse
|
47
|
Mehra A, Shi M, Baker CL, Colot HV, Loros JJ, Dunlap JC. A role for casein kinase 2 in the mechanism underlying circadian temperature compensation. Cell 2009; 137:749-60. [PMID: 19450520 DOI: 10.1016/j.cell.2009.03.019] [Citation(s) in RCA: 100] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2008] [Revised: 01/19/2009] [Accepted: 03/12/2009] [Indexed: 11/28/2022]
Abstract
Temperature compensation of circadian clocks is an unsolved problem with relevance to the general phenomenon of biological compensation. We identify casein kinase 2 (CK2) as a key regulator of temperature compensation of the Neurospora clock by determining that two long-standing clock mutants, chrono and period-3, displaying distinctive alterations in compensation encode the beta1 and alpha subunits of CK2, respectively. Reducing the dose of these subunits, particularly beta1, significantly alters temperature compensation without altering the enzyme's Q(10). By contrast, other kinases and phosphatases implicated in clock function do not play appreciable roles in temperature compensation. CK2 exerts its effects on the clock by directly phosphorylating FREQUENCY (FRQ), and this phosphorylation is compromised in CK2 hypomorphs. Finally, mutation of certain putative CK2 phosphosites on FRQ, shown to be phosphorylated in vivo, predictably alters temperature compensation profiles effectively phenocopying CK2 mutants.
Collapse
Affiliation(s)
- Arun Mehra
- Department of Genetics, Dartmouth Medical School, Hanover, NH 03755, USA
| | | | | | | | | | | |
Collapse
|
48
|
Abstract
The mammalian circadian clock influences the timing of many biological processes such as the sleep/wake cycle, metabolism, and cell division. Environmental cues such as light exposure can influence the timing of this system through the posttranslational modification of key components of the core molecular oscillator. We have previously shown that DNA damage can reset the circadian clock in a time-of-day-dependent manner in the filamentous fungus Neurospora crassa through the modulation of negative regulator FREQUENCY levels by PRD-4 (homologue of mammalian Chk2). We show that DNA damage, generated with either the radiomimetic drug methyl methane sulfonate or UV irradiation, in mouse embryonic fibroblasts isolated from PER2::LUC transgenic mice or in the NIH3T3 cell line, elicits similar responses. In addition to induction of phase advances, DNA damage caused a decrease in luciferase signal in PER2::LUC mouse embryonic fibroblast cells that is indicative of PER2 degradation. Finally, we show that the activity of the BMAL1 promoter is enhanced during DNA damage. These findings provide further evidence that the DNA damage-mediated response of the clock is conserved from lower eukaryotes to mammals.
Collapse
Affiliation(s)
- Joshua J. Gamsby
- Department of Genetics, Dartmouth Medical School, Hanover, New Hampshire
| | - Jennifer J. Loros
- Department of Genetics, Dartmouth Medical School, Hanover, New Hampshire
- Department of Biochemistry, Dartmouth Medical School, Hanover, New Hampshire
| | - Jay C. Dunlap
- Department of Genetics, Dartmouth Medical School, Hanover, New Hampshire
| |
Collapse
|
49
|
Chen CH, Ringelberg CS, Gross RH, Dunlap JC, Loros JJ. Genome-wide analysis of light-inducible responses reveals hierarchical light signalling in Neurospora. EMBO J 2009; 28:1029-42. [PMID: 19262566 DOI: 10.1038/emboj.2009.54] [Citation(s) in RCA: 212] [Impact Index Per Article: 14.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2008] [Accepted: 02/09/2009] [Indexed: 12/11/2022] Open
Abstract
White collar-1 (WC-1) and white collar-2 (WC-2) are essential for light-mediated responses in Neurospora crassa, but the molecular mechanisms underlying gene induction and the roles of other real and putative photoreceptors remain poorly characterized. Unsupervised hierarchical clustering of genome-wide microarrays reveals 5.6% of detectable transcripts, including several novel mediators, that are either early or late light responsive. Evidence is shown for photoreception in the absence of the dominant, and here confirmed, white collar complex (WCC) that regulates both types of light responses. VVD primarily modulates late responses, whereas light-responsive submerged protoperithecia-1 (SUB-1), a GATA family transcription factor, is essential for most late light gene expression. After a 15-min light stimulus, the WCC directly binds the sub-1 promoter. Bioinformatics analysis detects many early light response elements (ELREs), as well as identifying a late light response element (LLRE) required for wild-type activity of late light response promoters. The data provide a global picture of transcriptional response to light, as well as illuminating the cis- and trans-acting elements comprising the regulatory signalling cascade that governs the photobiological response.
Collapse
Affiliation(s)
- Chen-Hui Chen
- Department of Genetics, Dartmouth Medical School, Hanover, NH 03755-3844, USA
| | | | | | | | | |
Collapse
|
50
|
Duffield GE, Watson NP, Mantani A, Peirson SN, Robles-Murguia M, Loros JJ, Israel MA, Dunlap JC. A role for Id2 in regulating photic entrainment of the mammalian circadian system. Curr Biol 2009; 19:297-304. [PMID: 19217292 PMCID: PMC2648875 DOI: 10.1016/j.cub.2008.12.052] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2008] [Revised: 11/24/2008] [Accepted: 12/23/2008] [Indexed: 12/01/2022]
Abstract
Inhibitor of DNA binding genes (Id1-Id4) encode helix-loop-helix (HLH) transcriptional repressors associated with development and tumorigenesis [1, 2], but little is known concerning the function(s) of these genes in normal adult animals. Id2 was identified in DNA microarray screens for rhythmically expressed genes [3-5], and further analysis revealed a circadian pattern of expression of all four Id genes in multiple tissues including the suprachiasmatic nucleus. To explore an in vivo function, we generated and characterized deletion mutations of Id2 and of Id4. Id2(-/-) mice exhibit abnormally rapid entrainment and an increase in the magnitude of the phase shift of the pacemaker. A significant proportion of mice also exhibit disrupted rhythms when maintained under constant darkness. Conversely, Id4(-/-) mice did not exhibit a noticeable circadian phenotype. In vitro studies using an mPer1 and an AVP promoter reporter revealed the potential for ID1, ID2, and ID3 proteins to interact with the canonical basic HLH clock proteins BMAL1 and CLOCK. These data suggest that the Id genes may be important for entrainment and operation of the mammalian circadian system, potentially acting through BMAL1 and CLOCK targets.
Collapse
Affiliation(s)
- Giles E. Duffield
- Department of Genetics, Dartmouth Medical School, Hanover, NH 03755, USA
- Norris Cotton Cancer Center & Department of Pediatrics, Rubin Building, 1 Medical Center Drive, Lebanon, NH 03756, USA
- Department of Biological Sciences, Galvin Life Science Center, University of Notre Dame, Notre Dame, IN 46556, USA
| | - Nathan P. Watson
- Norris Cotton Cancer Center & Department of Pediatrics, Rubin Building, 1 Medical Center Drive, Lebanon, NH 03756, USA
| | - Akio Mantani
- Norris Cotton Cancer Center & Department of Pediatrics, Rubin Building, 1 Medical Center Drive, Lebanon, NH 03756, USA
| | - Stuart N. Peirson
- Nuffield Laboratory of Ophthalmology, University of Oxford, The John Radcliffe Hospital, Headley Way, Oxford OX3 9DU, UK
| | - Maricela Robles-Murguia
- Department of Biological Sciences, Galvin Life Science Center, University of Notre Dame, Notre Dame, IN 46556, USA
| | - Jennifer J. Loros
- Department of Genetics, Dartmouth Medical School, Hanover, NH 03755, USA
- Department of Biochemistry, Dartmouth Medical School, Hanover, NH 03755, USA
| | - Mark A. Israel
- Department of Genetics, Dartmouth Medical School, Hanover, NH 03755, USA
- Norris Cotton Cancer Center & Department of Pediatrics, Rubin Building, 1 Medical Center Drive, Lebanon, NH 03756, USA
| | - Jay C. Dunlap
- Department of Genetics, Dartmouth Medical School, Hanover, NH 03755, USA
| |
Collapse
|