1
|
Szőke A, Sárkány O, Schermann G, Kapuy O, Diernfellner ACR, Brunner M, Gyöngyösi N, Káldi K. Adaptation to glucose starvation is associated with molecular reorganization of the circadian clock in Neurospora crassa. eLife 2023; 12:79765. [PMID: 36625037 PMCID: PMC9831608 DOI: 10.7554/elife.79765] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2022] [Accepted: 12/12/2022] [Indexed: 01/11/2023] Open
Abstract
The circadian clock governs rhythmic cellular functions by driving the expression of a substantial fraction of the genome and thereby significantly contributes to the adaptation to changing environmental conditions. Using the circadian model organism Neurospora crassa, we show that molecular timekeeping is robust even under severe limitation of carbon sources, however, stoichiometry, phosphorylation and subcellular distribution of the key clock components display drastic alterations. Protein kinase A, protein phosphatase 2 A and glycogen synthase kinase are involved in the molecular reorganization of the clock. RNA-seq analysis reveals that the transcriptomic response of metabolism to starvation is highly dependent on the positive clock component WC-1. Moreover, our molecular and phenotypic data indicate that a functional clock facilitates recovery from starvation. We suggest that the molecular clock is a flexible network that allows the organism to maintain rhythmic physiology and preserve fitness even under long-term nutritional stress.
Collapse
Affiliation(s)
- Anita Szőke
- Department of Physiology, Semmelweis UniversityBudapestHungary
| | - Orsolya Sárkány
- Department of Physiology, Semmelweis UniversityBudapestHungary
| | - Géza Schermann
- Department of Neurovascular Cellbiology, University Hospital BonnBonnGermany
| | - Orsolya Kapuy
- Department of Molecular Biology, Semmelweis UniversityBudapestHungary
| | | | | | - Norbert Gyöngyösi
- Department of Molecular Biology, Semmelweis UniversityBudapestHungary
| | - Krisztina Káldi
- Department of Physiology, Semmelweis UniversityBudapestHungary
| |
Collapse
|
2
|
Eskandari R, Ratnayake L, Lakin-Thomas PL. Shared Components of the FRQ-Less Oscillator and TOR Pathway Maintain Rhythmicity in Neurospora. J Biol Rhythms 2021; 36:329-345. [PMID: 33825541 PMCID: PMC8276340 DOI: 10.1177/0748730421999948] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Molecular models for the endogenous oscillators that drive circadian rhythms in eukaryotes center on rhythmic transcription/translation of a small number of "clock genes." Although substantial evidence supports the concept that negative and positive transcription/translation feedback loops (TTFLs) are responsible for regulating the expression of these clock genes, certain rhythms in the filamentous fungus Neurospora crassa continue even when clock genes (frq, wc-1, and wc-2) are not rhythmically expressed. Identification of the rhythmic processes operating outside of the TTFL has been a major unresolved area in circadian biology. Our lab previously identified a mutation (vta) that abolishes FRQ-less rhythmicity of the conidiation rhythm and also affects rhythmicity when FRQ is functional. Further studies identified the vta gene product as a component of the TOR (Target of Rapamycin) nutrient-sensing pathway that is conserved in eukaryotes. We now report the discovery of TOR pathway components including GTR2 (homologous to the yeast protein Gtr2, and RAG C/D in mammals) as binding partners of VTA through co-immunoprecipitation (IP) and mass spectrometry analysis using a VTA-FLAG strain. Reciprocal IP with GTR2-FLAG found VTA as a binding partner. A Δgtr2 strain was deficient in growth responses to amino acids. Free-running conidiation rhythms in a FRQ-less strain were abolished in Δgtr2. Entrainment of a FRQ-less strain to cycles of heat pulses demonstrated that Δgtr2 is defective in entrainment. In all of these assays, Δgtr2 is similar to Δvta. In addition, expression of GTR2 protein was found to be rhythmic across two circadian cycles, and functional VTA was required for GTR2 rhythmicity. FRQ protein exhibited the expected rhythm in the presence of GTR2 but the rhythmic level of FRQ dampened in the absence of GTR2. These results establish association of VTA with GTR2, and their role in maintaining functional circadian rhythms through the TOR pathway.
Collapse
Affiliation(s)
- Rosa Eskandari
- Department of Biology, York University, Toronto, ON, Canada
| | | | | |
Collapse
|
3
|
Muñoz-Guzmán F, Caballero V, Larrondo LF. A global search for novel transcription factors impacting the Neurospora crassa circadian clock. G3 (BETHESDA, MD.) 2021; 11:jkab100. [PMID: 33792687 PMCID: PMC8495738 DOI: 10.1093/g3journal/jkab100] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/17/2020] [Accepted: 03/16/2021] [Indexed: 01/15/2023]
Abstract
Eukaryotic circadian oscillators share a common circuit architecture, a negative feedback loop in which a positive element activates the transcription of a negative one that then represses the action of the former, inhibiting its own expression. While studies in mammals and insects have revealed additional transcriptional inputs modulating the expression of core clock components, this has been less characterized in the model Neurospora crassa, where the participation of other transcriptional components impacting circadian clock dynamics remains rather unexplored. Thus, we sought to identify additional transcriptional regulators modulating the N. crassa clock, following a reverse genetic screen based on luminescent circadian reporters and a collection of transcription factors (TFs) knockouts, successfully covering close to 60% of them. Besides the canonical core clock components WC-1 and -2, none of the tested transcriptional regulators proved to be essential for rhythmicity. Nevertheless, we identified a set of 23 TFs that when absent lead to discrete, but significant, changes in circadian period. While the current level of analysis does not provide mechanistic information about how these new players modulate circadian parameters, the results of this screen reveal that an important number of light and clock-regulated TFs, involved in a plethora of processes, are capable of modulating the clockworks. This partial reverse genetic clock screen also exemplifies how the N. crassa knockout collection continues to serve as an expedite platform to address broad biological questions.
Collapse
Affiliation(s)
- Felipe Muñoz-Guzmán
- ANID—Millennium Science Initiative Program—Millennium Institute for Integrative Biology (iBio), Santiago 8331150, Chile
- Departamento de Genética Molecular y Microbiología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago 8331150, Chile
| | - Valeria Caballero
- Departamento de Genética Molecular y Microbiología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago 8331150, Chile
| | - Luis F Larrondo
- ANID—Millennium Science Initiative Program—Millennium Institute for Integrative Biology (iBio), Santiago 8331150, Chile
- Departamento de Genética Molecular y Microbiología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago 8331150, Chile
| |
Collapse
|
4
|
Cusumano P, Damulewicz M, Carbognin E, Caccin L, Puricella A, Specchia V, Bozzetti MP, Costa R, Mazzotta GM. The RNA Helicase BELLE Is Involved in Circadian Rhythmicity and in Transposons Regulation in Drosophila melanogaster. Front Physiol 2019; 10:133. [PMID: 30842743 PMCID: PMC6392097 DOI: 10.3389/fphys.2019.00133] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2017] [Accepted: 02/04/2019] [Indexed: 02/05/2023] Open
Abstract
Circadian clocks control and synchronize biological rhythms of several behavioral and physiological phenomena in most, if not all, organisms. Rhythm generation relies on molecular auto-regulatory oscillations of interlocked transcriptional-translational feedback loops. Rhythmic clock-gene expression is at the base of rhythmic protein accumulation, though post-transcriptional and post-translational mechanisms have evolved to adjust and consolidate the proper pace of the clock. In Drosophila, BELLE, a conserved DEAD-box RNA helicase playing important roles in reproductive capacity, is involved in the small RNA-mediated regulation associated to the piRNA pathway. Here, we report that BELLE is implicated in the circadian rhythmicity and in the regulation of endogenous transposable elements (TEs) in both nervous system and gonads. We suggest that BELLE acts as important element in the piRNA-mediated regulation of the TEs and raise the hypothesis that this specific regulation could represent another level of post-transcriptional control adopted by the clock to ensure the proper rhythmicity.
Collapse
Affiliation(s)
- Paola Cusumano
- Department of Biology, University of Padua, Padua, Italy
| | - Milena Damulewicz
- Department of Cell Biology and Imaging, Jagiellonian University, Kraków, Poland
| | | | - Laura Caccin
- Department of Biology, University of Padua, Padua, Italy
| | - Antonietta Puricella
- Department of Biological and Environmental Sciences and Technologies, University of Salento, Lecce, Italy
| | - Valeria Specchia
- Department of Biological and Environmental Sciences and Technologies, University of Salento, Lecce, Italy
| | - Maria Pia Bozzetti
- Department of Biological and Environmental Sciences and Technologies, University of Salento, Lecce, Italy
| | - Rodolfo Costa
- Department of Biology, University of Padua, Padua, Italy
| | | |
Collapse
|
5
|
Beyond Transcription: Fine-Tuning of Circadian Timekeeping by Post-Transcriptional Regulation. Genes (Basel) 2018; 9:genes9120616. [PMID: 30544736 PMCID: PMC6315869 DOI: 10.3390/genes9120616] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2018] [Revised: 11/29/2018] [Accepted: 12/03/2018] [Indexed: 12/28/2022] Open
Abstract
The circadian clock is an important endogenous timekeeper, helping plants to prepare for the periodic changes of light and darkness in their environment. The clockwork of this molecular timer is made up of clock proteins that regulate transcription of their own genes with a 24 h rhythm. Furthermore, the rhythmically expressed clock proteins regulate time-of-day dependent transcription of downstream genes, causing messenger RNA (mRNA) oscillations of a large part of the transcriptome. On top of the transcriptional regulation by the clock, circadian rhythms in mRNAs rely in large parts on post-transcriptional regulation, including alternative pre-mRNA splicing, mRNA degradation, and translational control. Here, we present recent insights into the contribution of post-transcriptional regulation to core clock function and to regulation of circadian gene expression in Arabidopsis thaliana.
Collapse
|
6
|
Circadian rhythms, metabolic oscillators, and the target of rapamycin (TOR) pathway: the Neurospora connection. Curr Genet 2018; 65:339-349. [DOI: 10.1007/s00294-018-0897-6] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2018] [Revised: 10/09/2018] [Accepted: 10/20/2018] [Indexed: 01/25/2023]
|
7
|
Ratnayake L, Adhvaryu KK, Kafes E, Motavaze K, Lakin-Thomas P. A component of the TOR (Target Of Rapamycin) nutrient-sensing pathway plays a role in circadian rhythmicity in Neurospora crassa. PLoS Genet 2018; 14:e1007457. [PMID: 29924817 PMCID: PMC6028147 DOI: 10.1371/journal.pgen.1007457] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2017] [Revised: 07/02/2018] [Accepted: 05/31/2018] [Indexed: 01/06/2023] Open
Abstract
The TOR (Target of Rapamycin) pathway is a highly-conserved signaling pathway in eukaryotes that regulates cellular growth and stress responses. The cellular response to amino acids or carbon sources such as glucose requires anchoring of the TOR kinase complex to the lysosomal/vacuolar membrane by the Ragulator (mammals) or EGO (yeast) protein complex. Here we report a connection between the TOR pathway and circadian (daily) rhythmicity. The molecular mechanism of circadian rhythmicity in all eukaryotes has long been thought to be transcription/translation feedback loops (TTFLs). In the model eukaryote Neurospora crassa, a TTFL including FRQ (frequency) and WCC (white collar complex) has been intensively studied. However, it is also well-known that rhythmicity can be seen in the absence of TTFL functioning. We previously isolated uv90 as a mutation that compromises FRQ-less rhythms and also damps the circadian oscillator when FRQ is present. We have now mapped the uv90 gene and identified it as NCU05950, homologous to the TOR pathway proteins EGO1 (yeast) and LAMTOR1 (mammals), and we have named the N. crassa protein VTA (vacuolar TOR-associated protein). The protein is anchored to the outer vacuolar membrane and deletion of putative acylation sites destroys this localization as well as the protein’s function in rhythmicity. A deletion of VTA is compromised in its growth responses to amino acids and glucose. We conclude that a key protein in the complex that anchors TOR to the vacuole plays a role in maintaining circadian (daily) rhythmicity. Our results establish a connection between the TOR pathway and circadian rhythms and point towards a network integrating metabolism and the circadian system. Circadian clocks drive 24-hour rhythms in living things at all levels of organization, from single cells to whole organisms. In spite of the importance of daily clocks for organizing the activities and internal functions of organisms, there are still many unsolved problems concerning the molecular mechanisms. In eukaryotes, a set of “clock proteins” turns on and off specific genes in a 24-hour feedback loop. This “clock gene feedback loop” has been the dominant idea about how clocks work for many years. However, some rhythms can still be seen when these feedback loops are not functioning. Using the fungus Neurospora crassa as a model organism, we have discovered a gene that is important for maintaining rhythms that continue without the known feedback loop. We have found that this gene codes for a protein that was already known to be important in helping cells to adjust their growth rate to adapt to varying availability of nutrients. Because the same gene is found in all eukaryotes, including mammals, this finding may point towards a universal clock mechanism that integrates nutritional needs with daily rhythms.
Collapse
|
8
|
Lee K, Shiva Kumar P, McQuade S, Lee JY, Park S, An Z, Piccoli B. Experimental and Mathematical Analyses Relating Circadian Period and Phase of Entrainment in Neurospora crassa. J Biol Rhythms 2017; 32:550-559. [PMID: 29183256 DOI: 10.1177/0748730417738611] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Circadian rhythms are observed in most organisms on earth and are known to play a major role in successful adaptation to the 24-h cycling environment. Circadian phenotypes are characterized by a free-running period that is observed in constant conditions and an entrained phase that is observed in cyclic conditions. Thus, the relationship between the free-running period and phase of entrainment is of interest. A popular simple rule has been that the entrained phase is the expression of the period in a cycling environment (i.e., that a short period causes an advanced phase and a long period causes a delayed phase). However, there are experimental data that are not explained by this simple relationship, and no systematic study has been done to explore all possible period-phase relationships. Here, we show the existence of stable period-phase relationships that are exceptions to this rule. First, we analyzed period-phase relationships using populations with different degrees of genome complexity. Second, we generated isogenic F1 populations by crossing 14 classical period mutants to the same female and analyzed 2 populations with a short period/delayed phase and a long period/advanced phase. Third, we generated a mathematical model to account for such variable relationships between period and phase. Our analyses support the view that the circadian period of an organism is not the only predictor of the entrained phase.
Collapse
Affiliation(s)
- Kwangwon Lee
- Department of Biology, Rutgers, The State University of New Jersey, Camden, New Jersey.,Center for Computational and Integrative Biology, Rutgers, The State University of New Jersey, Camden, New Jersey
| | - Prithvi Shiva Kumar
- Department of Biology, Rutgers, The State University of New Jersey, Camden, New Jersey
| | - Sean McQuade
- Center for Computational and Integrative Biology, Rutgers, The State University of New Jersey, Camden, New Jersey
| | - Joshua Y Lee
- Center for Computational and Integrative Biology, Rutgers, The State University of New Jersey, Camden, New Jersey
| | - Sohyun Park
- Department of Biology, Rutgers, The State University of New Jersey, Camden, New Jersey
| | - Zheming An
- Center for Computational and Integrative Biology, Rutgers, The State University of New Jersey, Camden, New Jersey
| | - Benedetto Piccoli
- Center for Computational and Integrative Biology, Rutgers, The State University of New Jersey, Camden, New Jersey
| |
Collapse
|
9
|
Gyöngyösi N, Szőke A, Ella K, Káldi K. The small G protein RAS2 is involved in the metabolic compensation of the circadian clock in the circadian model Neurospora crassa. J Biol Chem 2017; 292:14929-14939. [PMID: 28729421 DOI: 10.1074/jbc.m117.804922] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2017] [Indexed: 11/06/2022] Open
Abstract
Accumulating evidence from both experimental and clinical investigations indicates a tight interaction between metabolism and circadian timekeeping; however, knowledge of the underlying mechanism is still incomplete. Metabolic compensation allows circadian oscillators to run with a constant speed at different substrate levels and, therefore, is a substantial criterion of a robust rhythm in a changing environment. Because previous data have suggested a central role of RAS2-mediated signaling in the adaptation of yeast to different nutritional environments, we examined the involvement of RAS2 in the metabolic regulation of the clock in the circadian model organism Neurospora crassa We show that, in a ras2-deficient strain, the period is longer than in the control. Moreover, unlike in the WT, in Δras2, operation of the circadian clock was affected by glucose; compared with starvation conditions, the period was longer and the oscillation of expression of the frequency (frq) gene was dampened. In constant darkness, the delayed phosphorylation of the FRQ protein and the long-lasting accumulation of FRQ in the nucleus were in accordance with the longer period and the less robust rhythm in the mutant. Although glucose did not affect the subcellular distribution of FRQ in the WT, highly elevated FRQ levels were detected in the nucleus in Δras2 RAS2 interacted with the RAS-binding domain of the adenylate cyclase in vitro, and the cAMP analogue 8-bromo-cyclic AMP partially rescued the circadian phenotype in vivo We therefore propose that RAS2 acts via a cAMP-dependent pathway and exerts significant metabolic control on the Neurospora circadian clock.
Collapse
Affiliation(s)
- Norbert Gyöngyösi
- From the Department of Physiology, Semmelweis University, Tűzoltó u. 37-47, 1094 Budapest, Hungary
| | - Anita Szőke
- From the Department of Physiology, Semmelweis University, Tűzoltó u. 37-47, 1094 Budapest, Hungary
| | - Krisztina Ella
- From the Department of Physiology, Semmelweis University, Tűzoltó u. 37-47, 1094 Budapest, Hungary
| | - Krisztina Káldi
- From the Department of Physiology, Semmelweis University, Tűzoltó u. 37-47, 1094 Budapest, Hungary
| |
Collapse
|
10
|
A proteomic portrait of dinoflagellate chromatin reveals abundant RNA-binding proteins. Chromosoma 2017; 127:29-43. [PMID: 28852823 DOI: 10.1007/s00412-017-0643-8] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2017] [Revised: 08/09/2017] [Accepted: 08/11/2017] [Indexed: 12/20/2022]
Abstract
Dinoflagellate chromatin is unique among eukaryotes, as the chromosomes are permanently condensed in a liquid crystal state instead of being packed in nucleosomes. However, how it is organized is still an unsolved mystery, in part due to the lack of a comprehensive catalog of dinoflagellate nuclear proteins. Here, we report the results of CHromatin Enrichment for Proteomics (CHEP) followed by shotgun mass spectrometry sequencing of the chromatin-associated proteins from the dinoflagellate Lingulodinum polyedra. Our analysis identified proteins involved in DNA replication and repair, transcription, and mRNA splicing, and showed a low level of contamination by proteins from other organelles. A limited number of proteins containing DNA-binding domains were found, consistent with the lack of diversity of these proteins in dinoflagellate transcriptomes. However, the number of proteins containing RNA-binding domains was unexpectedly high supporting a potential role for this type of protein in mediating gene expression and chromatin organization. We also identified a number of proteins involved in chromosome condensation and cell cycle progression as well as a single histone protein (H4). Our results provide the first detailed look at the nuclear proteins associated with the unusual chromatin structure of dinoflagellate nuclei and provide important insights into the biochemical basis of its structure and function.
Collapse
|
11
|
Up-Frameshift Protein UPF1 Regulates Neurospora crassa Circadian and Diurnal Growth Rhythms. Genetics 2017; 206:1881-1893. [PMID: 28600326 DOI: 10.1534/genetics.117.202788] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2017] [Accepted: 05/31/2017] [Indexed: 01/24/2023] Open
Abstract
Nonsense-mediated RNA decay (NMD) is a crucial post-transcriptional regulatory mechanism that recognizes and eliminates aberrantly processed transcripts, and mediates the expression of normal gene transcripts. In this study, we report that in the filamentous fungus Neurospora crassa, the NMD factors play a conserved role in regulating the surveillance of NMD targets including premature termination codon (PTC)-containing transcripts and normal transcripts. The circadian rhythms in all of the knockout strains of upf1-3 genes, which encode the Up-frameshift proteins, were aberrant. The upf1 knockout strain displays a shortened circadian period, which can be restored by constantly expressing exogenous Up-frameshift protein 1 (UPF1). UPF1 regulates the circadian clock by modulating the splicing of the core clock gene frequency (frq) through spliceosome and spliceosome-related arginine/serine-rich splicing factors, which partly account for the short periods in the upf1 knockout strain. We also demonstrated that the clock genes including White Collar (WC)-1, WC-2, and FRQ are involved in controlling the diurnal growth rhythm, and UPF1 may affect the growth rhythms by mediating the FRQ protein levels in the daytime. These findings suggest that the NMD factors play important roles in regulating the circadian clock and diurnal growth rhythms in Neurospora.
Collapse
|