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Cai YD, Chow GK, Hidalgo S, Liu X, Jackson KC, Vasquez CD, Gao ZY, Lam VH, Tabuloc CA, Zheng H, Zhao C, Chiu JC. Alternative splicing of clock transcript mediates the response of circadian clocks to temperature changes. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.05.10.593646. [PMID: 38766142 PMCID: PMC11100826 DOI: 10.1101/2024.05.10.593646] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2024]
Abstract
Circadian clocks respond to temperature changes over the calendar year, allowing organisms to adjust their daily biological rhythms to optimize health and fitness. In Drosophila, seasonal adaptations and temperature compensation are regulated by temperature-sensitive alternative splicing (AS) of period (per) and timeless (tim) genes that encode key transcriptional repressors of clock gene expression. Although clock (clk) gene encodes the critical activator of clock gene expression, AS of its transcripts and its potential role in temperature regulation of clock function have not been explored. We therefore sought to investigate whether clk exhibits AS in response to temperature and the functional changes of the differentially spliced transcripts. We observed that clk transcripts indeed undergo temperature-sensitive AS. Specifically, cold temperature leads to the production of an alternative clk transcript, hereinafter termed clk-cold, which encodes a CLK isoform with an in-frame deletion of four amino acids proximal to the DNA binding domain. Notably, serine 13 (S13), which we found to be a CK1α-dependent phosphorylation site, is among the four amino acids deleted in CLK-cold protein. Using a combination of transgenic fly, tissue culture, and in vitro experiments, we demonstrated that upon phosphorylation at CLK(S13), CLK-DNA interaction is reduced, thus decreasing CLK occupancy at clock gene promoters. This is in agreement with our findings that CLK occupancy at clock genes and transcriptional output are elevated at cold temperature, which can be explained by the higher amounts of CLK-cold isoforms that lack S13 residue. This study provides new insights into the complex collaboration between AS and phospho-regulation in shaping temperature responses of the circadian clock.
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Affiliation(s)
- Yao D. Cai
- Department of Entomology and Nematology, College of Agricultural and Environmental Sciences, University of California Davis, One Shields Ave, Davis, CA 95616, USA
| | - Gary K. Chow
- Department of Entomology and Nematology, College of Agricultural and Environmental Sciences, University of California Davis, One Shields Ave, Davis, CA 95616, USA
| | - Sergio Hidalgo
- Department of Entomology and Nematology, College of Agricultural and Environmental Sciences, University of California Davis, One Shields Ave, Davis, CA 95616, USA
| | - Xianhui Liu
- Department of Entomology and Nematology, College of Agricultural and Environmental Sciences, University of California Davis, One Shields Ave, Davis, CA 95616, USA
| | - Kiya C. Jackson
- Department of Entomology and Nematology, College of Agricultural and Environmental Sciences, University of California Davis, One Shields Ave, Davis, CA 95616, USA
| | - Cameron D. Vasquez
- Department of Entomology and Nematology, College of Agricultural and Environmental Sciences, University of California Davis, One Shields Ave, Davis, CA 95616, USA
| | - Zita Y. Gao
- Department of Entomology and Nematology, College of Agricultural and Environmental Sciences, University of California Davis, One Shields Ave, Davis, CA 95616, USA
| | - Vu H. Lam
- Department of Entomology and Nematology, College of Agricultural and Environmental Sciences, University of California Davis, One Shields Ave, Davis, CA 95616, USA
| | - Christine A. Tabuloc
- Department of Entomology and Nematology, College of Agricultural and Environmental Sciences, University of California Davis, One Shields Ave, Davis, CA 95616, USA
| | - Haiyan Zheng
- Biological Mass Spectrometry Facility, Robert Wood Johnson Medical School and Rutgers, the State University of New Jersey, Piscataway, NJ 08854, USA
| | - Caifeng Zhao
- Biological Mass Spectrometry Facility, Robert Wood Johnson Medical School and Rutgers, the State University of New Jersey, Piscataway, NJ 08854, USA
| | - Joanna C. Chiu
- Department of Entomology and Nematology, College of Agricultural and Environmental Sciences, University of California Davis, One Shields Ave, Davis, CA 95616, USA
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2
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Ma D, Ojha P, Yu AD, Araujo MS, Luo W, Keefer E, Díaz MM, Wu M, Joiner WJ, Abruzzi KC, Rosbash M. Timeless noncoding DNA contains cell-type preferential enhancers important for proper Drosophila circadian regulation. Proc Natl Acad Sci U S A 2024; 121:e2321338121. [PMID: 38568969 PMCID: PMC11009632 DOI: 10.1073/pnas.2321338121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2023] [Accepted: 03/05/2024] [Indexed: 04/05/2024] Open
Abstract
To address the contribution of transcriptional regulation to Drosophila clock gene expression and to behavior, we generated a series of CRISPR-mediated deletions within two regions of the circadian gene timeless (tim), an intronic E-box region and an upstream E-box region that are both recognized by the key transcription factor Clock (Clk) and its heterodimeric partner Cycle. The upstream deletions but not an intronic deletion dramatically impact tim expression in fly heads; the biggest upstream deletion reduces peak RNA levels and tim RNA cycling amplitude to about 15% of normal, and there are similar effects on tim protein (TIM). The cycling amplitude of other clock genes is also strongly reduced, in these cases due to increases in trough levels. These data underscore the important contribution of the upstream E-box enhancer region to tim expression and of TIM to clock gene transcriptional repression in fly heads. Surprisingly, tim expression in clock neurons is only modestly affected by the biggest upstream deletion and is similarly affected by a deletion of the intronic E-box region. This distinction between clock neurons and glia is paralleled by a dramatically enhanced accessibility of the intronic enhancer region within clock neurons. This distinctive feature of tim chromatin was revealed by ATAC-seq (assay for transposase-accessible chromatin with sequencing) assays of purified neurons and glia as well as of fly heads. The enhanced cell type-specific accessibility of the intronic enhancer region explains the resilience of clock neuron tim expression and circadian behavior to deletion of the otherwise more prominent upstream tim E-box region.
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Affiliation(s)
- Dingbang Ma
- Interdisciplinary Research Center on Biology and Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, Shanghai201210, China
- Shanghai Key Laboratory of Aging Studies, Shanghai201210, China
| | - Pranav Ojha
- HHMI, Brandeis University, Waltham, MA02453
- Department of Biology, Brandeis University, Waltham, MA02453
| | - Albert D. Yu
- HHMI, Brandeis University, Waltham, MA02453
- Department of Biology, Brandeis University, Waltham, MA02453
| | - Maisa S. Araujo
- Laboratory of Entomology, Fiocruz Rondônia and Programa de Pós-Graduação em Biologia Experimental/Programa Nacional de Pós-Doutorado, Federal University Foundation of Rondônia, Porto Velho76801-974, Brazil
| | - Weifei Luo
- Guangxi Academy of Sciences, Nanning530003, China
| | - Evelyn Keefer
- HHMI, Brandeis University, Waltham, MA02453
- Department of Biology, Brandeis University, Waltham, MA02453
| | - Madelen M. Díaz
- The Miami Project to Cure Paralysis, Department of Neurosurgery, University of Miami Miller School of Medicine, Miami, FL33136
| | - Meilin Wu
- Department of Pharmacology, University of California, San Diego, La Jolla, CA92093
| | - William J. Joiner
- Department of Pharmacology, University of California, San Diego, La Jolla, CA92093
- Center for Circadian Biology, University of California, San Diego, La Jolla, CA92093
| | - Katharine C. Abruzzi
- HHMI, Brandeis University, Waltham, MA02453
- Department of Biology, Brandeis University, Waltham, MA02453
| | - Michael Rosbash
- HHMI, Brandeis University, Waltham, MA02453
- Department of Biology, Brandeis University, Waltham, MA02453
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Hewson L, Choo A, Webber DL, Trim PJ, Snel MF, Fedele AO, Hopwood JJ, Hemsley KM, O'Keefe LV. Drosophila melanogaster models of MPS IIIC (Hgsnat-deficiency) highlight the role of glia in disease presentation. J Inherit Metab Dis 2024; 47:340-354. [PMID: 38238109 DOI: 10.1002/jimd.12712] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/03/2023] [Revised: 12/18/2023] [Accepted: 12/21/2023] [Indexed: 03/16/2024]
Abstract
Sanfilippo syndrome (Mucopolysaccharidosis type III or MPS III) is a recessively inherited neurodegenerative lysosomal storage disorder. Mutations in genes encoding enzymes in the heparan sulphate degradation pathway lead to the accumulation of partially degraded heparan sulphate, resulting ultimately in the development of neurological deficits. Mutations in the gene encoding the membrane protein heparan-α-glucosaminide N-acetyltransferase (HGSNAT; EC2.3.1.78) cause MPS IIIC (OMIM#252930), typified by impaired cognition, sleep-wake cycle changes, hyperactivity and early death, often before adulthood. The precise disease mechanism that causes symptom emergence remains unknown, posing a significant challenge in the development of effective therapeutics. As HGSNAT is conserved in Drosophila melanogaster, we now describe the creation and characterisation of the first Drosophila models of MPS IIIC. Flies with either an endogenous insertion mutation or RNAi-mediated knockdown of hgsnat were confirmed to have a reduced level of HGSNAT transcripts and age-dependent accumulation of heparan sulphate leading to engorgement of the endo/lysosomal compartment. This resulted in abnormalities at the pre-synapse, defective climbing and reduced overall activity. Altered circadian rhythms (shift in peak morning activity) were seen in hgsnat neuronal knockdown lines. Further, when hgsnat was knocked down in specific glial subsets (wrapping, cortical, astrocytes or subperineural glia), impaired climbing or reduced activity was noted, implying that hgsnat function in these specific glial subtypes contributes significantly to this behaviour and targeting treatments to these cell groups may be necessary to ameliorate or prevent symptom onset. These novel models of MPS IIIC provide critical research tools for delineating the key cellular pathways causal in the onset of neurodegeneration in this presently untreatable disorder.
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Affiliation(s)
- Laura Hewson
- Department of Molecular and Biomedical Science, School of Biological Sciences, The University of Adelaide, Adelaide, South Australia, Australia
| | - Amanda Choo
- Department of Molecular and Biomedical Science, School of Biological Sciences, The University of Adelaide, Adelaide, South Australia, Australia
| | - Dani L Webber
- Department of Molecular and Biomedical Science, School of Biological Sciences, The University of Adelaide, Adelaide, South Australia, Australia
| | - Paul J Trim
- Proteomics, Metabolomics & MS-Imaging Core, South Australian Health and Medical Research Institute, Adelaide, South Australia, Australia
| | - Marten F Snel
- Proteomics, Metabolomics & MS-Imaging Core, South Australian Health and Medical Research Institute, Adelaide, South Australia, Australia
| | - Anthony O Fedele
- Hopwood Centre for Neurobiology, South Australian Health and Medical Research Institute, Adelaide, South Australia, Australia
| | - John J Hopwood
- Hopwood Centre for Neurobiology, South Australian Health and Medical Research Institute, Adelaide, South Australia, Australia
| | - Kim M Hemsley
- Childhood Dementia Research Group, Flinders Health and Medical Research Institute, Flinders University, Bedford Park, South Australia, Australia
| | - Louise V O'Keefe
- Department of Molecular and Biomedical Science, School of Biological Sciences, The University of Adelaide, Adelaide, South Australia, Australia
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Steward RA, Pruisscher P, Roberts KT, Wheat CW. Genetic constraints in genes exhibiting splicing plasticity in facultative diapause. Heredity (Edinb) 2024; 132:142-155. [PMID: 38291272 PMCID: PMC10923799 DOI: 10.1038/s41437-024-00669-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2023] [Revised: 12/28/2023] [Accepted: 01/03/2024] [Indexed: 02/01/2024] Open
Abstract
Phenotypic plasticity is produced and maintained by processes regulating the transcriptome. While differential gene expression is among the most important of these processes, relatively little is known about other sources of transcriptional variation. Previous work suggests that alternative splicing plays an extensive and functionally unique role in transcriptional plasticity, though plastically spliced genes may be more constrained than the remainder of expressed genes. In this study, we explore the relationship between expression and splicing plasticity, along with the genetic diversity in those genes, in an ecologically consequential polyphenism: facultative diapause. Using 96 samples spread over two tissues and 10 timepoints, we compare the extent of differential splicing and expression between diapausing and direct developing pupae of the butterfly Pieris napi. Splicing differs strongly between diapausing and direct developing trajectories but alters a smaller and functionally unique set of genes compared to differential expression. We further test the hypothesis that among these expressed loci, plastically spliced genes are likely to experience the strongest purifying selection to maintain seasonally plastic phenotypes. Genes with unique transcriptional changes through diapause consistently had the lowest nucleotide diversity, and this effect was consistently stronger among genes that were differentially spliced compared to those with just differential expression through diapause. Further, the strength of negative selection was higher in the population expressing diapause every generation. Our results suggest that maintenance of the molecular mechanisms involved in diapause progression, including post-transcriptional modifications, are highly conserved and likely to experience genetic constraints, especially in northern populations of P. napi.
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Affiliation(s)
- Rachel A Steward
- Zoology Department, Stockholm University, Stockholm, Sweden.
- Biology Department, Lund University, Lund, Sweden.
| | - Peter Pruisscher
- Zoology Department, Stockholm University, Stockholm, Sweden
- Science for Life Laboratory, Department of Microbiology, Tumor and Cell Biology, Karolinska Institute, Stockholm, Sweden
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Benjamin JI, Pollock DM. Current perspective on circadian function of the kidney. Am J Physiol Renal Physiol 2024; 326:F438-F459. [PMID: 38134232 PMCID: PMC11207578 DOI: 10.1152/ajprenal.00247.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2023] [Revised: 11/28/2023] [Accepted: 12/18/2023] [Indexed: 12/24/2023] Open
Abstract
Behavior and function of living systems are synchronized by the 24-h rotation of the Earth that guides physiology according to time of day. However, when behavior becomes misaligned from the light-dark cycle, such as in rotating shift work, jet lag, and even unusual eating patterns, adverse health consequences such as cardiovascular or cardiometabolic disease can arise. The discovery of cell-autonomous molecular clocks expanded interest in regulatory systems that control circadian physiology including within the kidney, where function varies along a 24-h cycle. Our understanding of the mechanisms for circadian control of physiology is in the early stages, and so the present review provides an overview of what is known and the many gaps in our current understanding. We include a particular focus on the impact of eating behaviors, especially meal timing. A better understanding of the mechanisms guiding circadian function of the kidney is expected to reveal new insights into causes and consequences of a wide range of disorders involving the kidney, including hypertension, obesity, and chronic kidney disease.
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Affiliation(s)
- Jazmine I Benjamin
- Section of Cardio-Renal Physiology and Medicine, Division of Nephrology, Department of Medicine, University of Alabama at Birmingham, Birmingham, Alabama, United States
| | - David M Pollock
- Section of Cardio-Renal Physiology and Medicine, Division of Nephrology, Department of Medicine, University of Alabama at Birmingham, Birmingham, Alabama, United States
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6
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Jauregui-Lozano J, McGovern SE, Bakhle KM, Hagins AC, Weake VM. Establishing the contribution of active histone methylation marks to the aging transcriptional landscape of Drosophila photoreceptors. Sci Rep 2023; 13:5105. [PMID: 36991154 PMCID: PMC10060402 DOI: 10.1038/s41598-023-32273-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2022] [Accepted: 03/24/2023] [Indexed: 03/31/2023] Open
Abstract
Studies in multiple organisms have shown that aging is accompanied by several molecular phenotypes that include dysregulation of chromatin. Since chromatin regulates DNA-based processes such as transcription, alterations in chromatin modifications could impact the transcriptome and function of aging cells. In flies, as in mammals, the aging eye undergoes changes in gene expression that correlate with declining visual function and increased risk of retinal degeneration. However, the causes of these transcriptome changes are poorly understood. Here, we profiled chromatin marks associated with active transcription in the aging Drosophila eye to understand how chromatin modulates transcriptional outputs. We found that both H3K4me3 and H3K36me3 globally decrease across all actively expressed genes with age. However, we found no correlation with changes in differential gene expression. Downregulation of the H3K36me3 methyltransferase Set2 in young photoreceptors revealed significant changes in splicing events that overlapped significantly with those observed in aging photoreceptors. These overlapping splicing events impacted multiple genes involved in phototransduction and neuronal function. Since proper splicing is essential for visual behavior, and because aging Drosophila undergo a decrease in visual function, our data suggest that H3K36me3 could play a role in maintaining visual function in the aging eye through regulating alternative splicing.
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Affiliation(s)
- Juan Jauregui-Lozano
- Department of Biochemistry, Purdue University, 175 S. University Street, West Lafayette, IN, 47907, USA
- University of California San Diego, San Diego, CA, 92093, USA
| | - Sarah E McGovern
- Department of Biochemistry, Purdue University, 175 S. University Street, West Lafayette, IN, 47907, USA
| | - Kimaya M Bakhle
- Department of Biochemistry, Purdue University, 175 S. University Street, West Lafayette, IN, 47907, USA
| | - Arrianna C Hagins
- Department of Biochemistry, Purdue University, 175 S. University Street, West Lafayette, IN, 47907, USA
| | - Vikki M Weake
- Department of Biochemistry, Purdue University, 175 S. University Street, West Lafayette, IN, 47907, USA.
- Purdue Center for Cancer Research, Purdue University, West Lafayette, IN, 47907, USA.
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7
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Hidalgo S, Anguiano M, Tabuloc CA, Chiu JC. Seasonal cues act through the circadian clock and pigment-dispersing factor to control EYES ABSENT and downstream physiological changes. Curr Biol 2023; 33:675-687.e5. [PMID: 36708710 PMCID: PMC9992282 DOI: 10.1016/j.cub.2023.01.006] [Citation(s) in RCA: 10] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2022] [Revised: 12/05/2022] [Accepted: 01/05/2023] [Indexed: 01/28/2023]
Abstract
Organisms adapt to seasonal changes in photoperiod and temperature to survive; however, the mechanisms by which these signals are integrated in the brain to alter seasonal biology are poorly understood. We previously reported that EYES ABSENT (EYA) shows higher levels in cold temperature or short photoperiod and promotes winter physiology in Drosophila. Nevertheless, how EYA senses seasonal cues is unclear. Pigment-dispersing factor (PDF) is a neuropeptide important for regulating circadian output rhythms. Interestingly, PDF has also been shown to regulate seasonality, suggesting that it may mediate the function of the circadian clock in modulating seasonal physiology. In this study, we investigated the role of EYA in mediating the function of PDF on seasonal biology. We observed that PDF abundance is lower on cold and short days as compared with warm and long days, contrary to what was previously observed for EYA. We observed that manipulating PDF signaling in eya+ fly brain neurons, where EYA and PDF receptor are co-expressed, modulates seasonal adaptations in daily activity rhythm and ovary development via EYA-dependent and EYA-independent mechanisms. At the molecular level, altering PDF signaling impacted EYA protein abundance. Specifically, we showed that protein kinase A (PKA), an effector of PDF signaling, phosphorylates EYA promoting its degradation, thus explaining the opposite responses of PDF and EYA abundance to changes in seasonal cues. In summary, our results support a model in which PDF signaling negatively modulates EYA levels to regulate seasonal physiology, linking the circadian clock to the modulation of seasonal adaptations.
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Affiliation(s)
- Sergio Hidalgo
- Department of Entomology and Nematology, College of Agricultural and Environmental Sciences, University of California, Davis, One Shields Avenue, Davis, CA 95616, USA
| | - Maribel Anguiano
- Department of Entomology and Nematology, College of Agricultural and Environmental Sciences, University of California, Davis, One Shields Avenue, Davis, CA 95616, USA
| | - Christine A Tabuloc
- Department of Entomology and Nematology, College of Agricultural and Environmental Sciences, University of California, Davis, One Shields Avenue, Davis, CA 95616, USA
| | - Joanna C Chiu
- Department of Entomology and Nematology, College of Agricultural and Environmental Sciences, University of California, Davis, One Shields Avenue, Davis, CA 95616, USA.
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8
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Tabuloc CA, Cai YD, Kwok RS, Chan EC, Hidalgo S, Chiu JC. CLOCK and TIMELESS regulate rhythmic occupancy of the BRAHMA chromatin-remodeling protein at clock gene promoters. PLoS Genet 2023; 19:e1010649. [PMID: 36809369 PMCID: PMC9983840 DOI: 10.1371/journal.pgen.1010649] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2022] [Revised: 03/03/2023] [Accepted: 02/02/2023] [Indexed: 02/23/2023] Open
Abstract
Circadian clock and chromatin-remodeling complexes are tightly intertwined systems that regulate rhythmic gene expression. The circadian clock promotes rhythmic expression, timely recruitment, and/or activation of chromatin remodelers, while chromatin remodelers regulate accessibility of clock transcription factors to the DNA to influence expression of clock genes. We previously reported that the BRAHMA (BRM) chromatin-remodeling complex promotes the repression of circadian gene expression in Drosophila. In this study, we investigated the mechanisms by which the circadian clock feeds back to modulate daily BRM activity. Using chromatin immunoprecipitation, we observed rhythmic BRM binding to clock gene promoters despite constitutive BRM protein expression, suggesting that factors other than protein abundance are responsible for rhythmic BRM occupancy at clock-controlled loci. Since we previously reported that BRM interacts with two key clock proteins, CLOCK (CLK) and TIMELESS (TIM), we examined their effect on BRM occupancy to the period (per) promoter. We observed reduced BRM binding to the DNA in clk null flies, suggesting that CLK is involved in enhancing BRM occupancy to initiate transcriptional repression at the conclusion of the activation phase. Additionally, we observed reduced BRM binding to the per promoter in flies overexpressing TIM, suggesting that TIM promotes BRM removal from DNA. These conclusions are further supported by elevated BRM binding to the per promoter in flies subjected to constant light and experiments in Drosophila tissue culture in which the levels of CLK and TIM are manipulated. In summary, this study provides new insights into the reciprocal regulation between the circadian clock and the BRM chromatin-remodeling complex.
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Affiliation(s)
- Christine A. Tabuloc
- Department of Entomology and Nematology, College of Agricultural and Environmental Sciences, University of California Davis, Davis, California, United States of America
| | - Yao D. Cai
- Department of Entomology and Nematology, College of Agricultural and Environmental Sciences, University of California Davis, Davis, California, United States of America
| | - Rosanna S. Kwok
- Department of Entomology and Nematology, College of Agricultural and Environmental Sciences, University of California Davis, Davis, California, United States of America
| | - Elizabeth C. Chan
- Department of Entomology and Nematology, College of Agricultural and Environmental Sciences, University of California Davis, Davis, California, United States of America
| | - Sergio Hidalgo
- Department of Entomology and Nematology, College of Agricultural and Environmental Sciences, University of California Davis, Davis, California, United States of America
| | - Joanna C. Chiu
- Department of Entomology and Nematology, College of Agricultural and Environmental Sciences, University of California Davis, Davis, California, United States of America
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Andreatta G, Montagnese S, Costa R. Natural alleles of the clock gene timeless differentially affect life-history traits in Drosophila. Front Physiol 2023; 13:1092951. [PMID: 36703932 PMCID: PMC9871817 DOI: 10.3389/fphys.2022.1092951] [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: 11/08/2022] [Accepted: 12/30/2022] [Indexed: 01/12/2023] Open
Abstract
Circadian clocks orchestrate a variety of physiological and behavioural functions within the 24-h day. These timekeeping systems have also been implicated in developmental and reproductive processes that span more (or less) than 24 h. Whether natural alleles of cardinal clock genes affect entire sets of life-history traits (i.e., reproductive arrest, developmental time, fecundity), thus providing a wider substrate for seasonal adaptation, remains unclear. Here we show that natural alleles of the timeless (tim) gene of Drosophila melanogaster, previously shown to modulate flies' propensity to enter reproductive dormancy, differentially affect correlated traits such as early-life fecundity and developmental time. Homozygous flies expressing the shorter TIM isoform (encoded by the s-tim allele) not only show a lower dormancy incidence compared to those homozygous for ls-tim (which produce both the short and an N-terminal additional 23-residues longer TIM isoform), but also higher fecundity in the first 12 days of adult life. Moreover, s-tim homozygous flies develop faster than ls-tim homozygous flies at both warm (25°C) and cold (15°C) temperatures, with the gap being larger at 15°C. In summary, this phenotypic analysis shows that natural variants of tim affect a set of life-history traits associated with reproductive dormancy in Drosophila. We speculate that this provides further adaptive advantage in temperate regions (with seasonal changes) and propose that the underlying mechanisms might not be exclusively dependent on photoperiod, as previously suggested.
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Affiliation(s)
- Gabriele Andreatta
- Department of Biology, University of Padua, Padua, Italy,Max Perutz Laboratories, University of Vienna, Vienna, Austria,*Correspondence: Gabriele Andreatta, ; Rodolfo Costa,
| | - Sara Montagnese
- Department of Medicine, University of Padua, Padua, Italy,Chronobiology, Faculty of Health and Medical Sciences, University of Surrey, Guildford, United Kingdom
| | - Rodolfo Costa
- Department of Biology, University of Padua, Padua, Italy,Chronobiology, Faculty of Health and Medical Sciences, University of Surrey, Guildford, United Kingdom,Institute of Neuroscience, National Research Council (CNR), Padua, Italy,*Correspondence: Gabriele Andreatta, ; Rodolfo Costa,
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10
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Li Y, Yang X, Zhao Z, Du J. SRP54 mediates circadian rhythm-related, temperature-dependent gene expression in Drosophila. Genomics 2022; 114:110512. [PMID: 36273743 DOI: 10.1016/j.ygeno.2022.110512] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2022] [Revised: 10/14/2022] [Accepted: 10/19/2022] [Indexed: 01/15/2023]
Abstract
Recent studies have shown that alternative splicing (AS) plays an important role in regulating circadian rhythm. However, it is not clear whether clock neuron-specific AS is circadian rhythm dependent and what genetic and environmental factors mediate the circadian control of AS. By genome-wide RNA sequencing, we identified SRP54 is one of the Clock (Clk) dependent alternative splicing factors. Genetic interaction between Clock and SRP54 alleles showed that the enhancement of the circadian phenotype increased with temperature, being strongest at 29 °C and weakest at 18 °C. The alternative splicing and differential gene expression profile of Clock and SRP54 overlapped with the circadian-related gene profiles identified in various genome-wide studies, indicating that SRP54 is involved in circadian rhythm. By analyzing of the RNA-seq results at different temperatures, we found the roles of Clock and SRP54 are temperature dependent. We also found multiple novel temperature-dependent transcripts not documented in current databases.
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Affiliation(s)
- Yahong Li
- Department of Entomology, MOA Key Lab of Pest Monitoring and Green Management, College of Plant Protection, China Agricultural University, Beijing 100193, China
| | - Xingzhuo Yang
- Department of Entomology, MOA Key Lab of Pest Monitoring and Green Management, College of Plant Protection, China Agricultural University, Beijing 100193, China
| | - Zhangwu Zhao
- Department of Entomology, MOA Key Lab of Pest Monitoring and Green Management, College of Plant Protection, China Agricultural University, Beijing 100193, China
| | - Juan Du
- Department of Entomology, MOA Key Lab of Pest Monitoring and Green Management, College of Plant Protection, China Agricultural University, Beijing 100193, China.
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Yildirim E, Curtis R, Hwangbo DS. Roles of peripheral clocks: lessons from the fly. FEBS Lett 2022; 596:263-293. [PMID: 34862983 PMCID: PMC8844272 DOI: 10.1002/1873-3468.14251] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2021] [Revised: 11/26/2021] [Accepted: 11/29/2021] [Indexed: 02/03/2023]
Abstract
To adapt to and anticipate rhythmic changes in the environment such as daily light-dark and temperature cycles, internal timekeeping mechanisms called biological clocks evolved in a diverse set of organisms, from unicellular bacteria to humans. These biological clocks play critical roles in organisms' fitness and survival by temporally aligning physiological and behavioral processes to the external cues. The central clock is located in a small subset of neurons in the brain and drives daily activity rhythms, whereas most peripheral tissues harbor their own clock systems, which generate metabolic and physiological rhythms. Since the discovery of Drosophila melanogaster clock mutants in the early 1970s, the fruit fly has become an extensively studied model organism to investigate the mechanism and functions of circadian clocks. In this review, we primarily focus on D. melanogaster to survey key discoveries and progresses made over the past two decades in our understanding of peripheral clocks. We discuss physiological roles and molecular mechanisms of peripheral clocks in several different peripheral tissues of the fly.
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Affiliation(s)
- Evrim Yildirim
- unaffiliated, Istanbul, Turkey,Correspondence: Dae-Sung Hwangbo, Ph.D., Department of Biology, University of Louisville, 139 Life Sciences Bldg., Louisville, KY, 40292, USA. , Tel: 1-502-852-5937; Evrim Yildirim, Ph.D., Eskibostan Sok. No:6 Celebi Sitesi: A-2, Kartal, Istanbul, 34860, Turkey. , Tel: 90-546-919-02-81
| | - Rachel Curtis
- Department of Biology, University of Louisville, Louisville, KY, USA
| | - Dae-Sung Hwangbo
- Department of Biology, University of Louisville, Louisville, KY, USA,Correspondence: Dae-Sung Hwangbo, Ph.D., Department of Biology, University of Louisville, 139 Life Sciences Bldg., Louisville, KY, 40292, USA. , Tel: 1-502-852-5937; Evrim Yildirim, Ph.D., Eskibostan Sok. No:6 Celebi Sitesi: A-2, Kartal, Istanbul, 34860, Turkey. , Tel: 90-546-919-02-81
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12
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Perception of Daily Time: Insights from the Fruit Flies. INSECTS 2021; 13:insects13010003. [PMID: 35055846 PMCID: PMC8780729 DOI: 10.3390/insects13010003] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/16/2021] [Revised: 11/21/2021] [Accepted: 12/07/2021] [Indexed: 11/17/2022]
Abstract
We create mental maps of the space that surrounds us; our brains also compute time—in particular, the time of day. Visual, thermal, social, and other cues tune the clock-like timekeeper. Consequently, the internal clock synchronizes with the external day-night cycles. In fact, daylength itself varies, causing the change of seasons and forcing our brain clock to accommodate layers of plasticity. However, the core of the clock, i.e., its molecular underpinnings, are highly resistant to perturbations, while the way animals adapt to the daily and annual time shows tremendous biological diversity. How can this be achieved? In this review, we will focus on 75 pairs of clock neurons in the Drosophila brain to understand how a small neural network perceives and responds to the time of the day, and the time of the year.
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13
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Fagan RR, Kearney PJ, Luethi D, Bolden NC, Sitte HH, Emery P, Melikian HE. Dopaminergic Ric GTPase activity impacts amphetamine sensitivity and sleep quality in a dopamine transporter-dependent manner in Drosophila melanogaster. Mol Psychiatry 2021; 26:7793-7802. [PMID: 34471250 PMCID: PMC8881384 DOI: 10.1038/s41380-021-01275-y] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/08/2021] [Revised: 07/28/2021] [Accepted: 08/20/2021] [Indexed: 02/07/2023]
Abstract
Dopamine (DA) is required for movement, sleep, and reward, and DA signaling is tightly controlled by the presynaptic DA transporter (DAT). Therapeutic and addictive psychostimulants, including methylphenidate (Ritalin; MPH), cocaine, and amphetamine (AMPH), markedly elevate extracellular DA via their actions as competitive DAT inhibitors (MPH, cocaine) and substrates (AMPH). DAT silencing in mice and invertebrates results in hyperactivity, reduced sleep, and blunted psychostimulant responses, highlighting DAT's essential role in DA-dependent behaviors. DAT surface expression is not static; rather it is dynamically regulated by endocytic trafficking. PKC-stimulated DAT endocytosis requires the neuronal GTPase, Rit2, and Rit2 silencing in mouse DA neurons impacts psychostimulant sensitivity. However, it is unknown whether or not Rit2-mediated changes in psychostimulant sensitivity are DAT-dependent. Here, we leveraged Drosophila melanogaster to test whether the Drosophila Rit2 ortholog, Ric, impacts dDAT function, trafficking, and DA-dependent behaviors. Orthologous to hDAT and Rit2, dDAT and Ric directly interact, and the constitutively active Ric mutant Q117L increased dDAT surface levels and function in cell lines and ex vivo Drosophila brains. Moreover, DAergic RicQ117L expression caused sleep fragmentation in a DAT-dependent manner but had no effect on total sleep and daily locomotor activity. Importantly, we found that Rit2 is required for AMPH-stimulated DAT internalization in mouse striatum, and that DAergic RicQ117L expression significantly increased Drosophila AMPH sensitivity in a DAT-dependent manner, suggesting a conserved impact of Ric-dependent DAT trafficking on AMPH sensitivity. These studies support that the DAT/Rit2 interaction impacts both baseline behaviors and AMPH sensitivity, potentially by regulating DAT trafficking.
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Affiliation(s)
- Rita R. Fagan
- Brudnick Neuropsychiatric Research Institute, Department of Neurobiology, UMASS Medical School, Worcester, MA
| | - Patrick J. Kearney
- Brudnick Neuropsychiatric Research Institute, Department of Neurobiology, UMASS Medical School, Worcester, MA
| | - Dino Luethi
- Medical University Vienna, Center for Physiology and Pharmacology, Institute of Pharmacology, Vienna, Austria, A-1090
| | - Nicholas C. Bolden
- Brudnick Neuropsychiatric Research Institute, Department of Neurobiology, UMASS Medical School, Worcester, MA
| | - Harald H. Sitte
- Medical University Vienna, Center for Physiology and Pharmacology, Institute of Pharmacology, Vienna, Austria, A-1090
| | - Patrick Emery
- Department of Neurobiology, UMASS Medical School, Worcester, MA
| | - Haley E. Melikian
- Brudnick Neuropsychiatric Research Institute, Department of Neurobiology, UMASS Medical School, Worcester, MA,Address correspondence to: Haley Melikian, Ph.D., Department of Neurobiology, UMASS Medical School, LRB 726, 364 Plantation St., Worcester, MA 01605, 774-455-4308 (phone), 508-856-6266 (fax),
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14
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Cai YD, Chiu JC. Timeless in animal circadian clocks and beyond. FEBS J 2021; 289:6559-6575. [PMID: 34699674 PMCID: PMC9038958 DOI: 10.1111/febs.16253] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2021] [Revised: 10/09/2021] [Accepted: 10/26/2021] [Indexed: 12/13/2022]
Abstract
TIMELESS (TIM) was first identified as a molecular cog in the Drosophila circadian clock. Almost three decades of investigations have resulted in an insightful model describing the critical role of Drosophila TIM (dTIM) in circadian timekeeping in insects, including its function in mediating light entrainment and temperature compensation of the molecular clock. Furthermore, exciting discoveries on its sequence polymorphism and thermosensitive alternative RNA splicing have also established its role in regulating seasonal biology. Although mammalian TIM (mTIM), its mammalian paralog, was first identified as a potential circadian clock component in 1990s due to sequence similarity to dTIM, its role in clock regulation has been more controversial. Mammalian TIM has now been characterized as a DNA replication fork component and has been shown to promote fork progression and participate in cell cycle checkpoint signaling in response to DNA damage. Despite defective circadian rhythms displayed by mtim mutants, it remains controversial whether the regulation of circadian clocks by mTIM is direct, especially given the interconnection between the cell cycle and circadian clocks. In this review, we provide a historical perspective on the identification of animal tim genes, summarize the roles of TIM proteins in biological timing and genomic stability, and draw parallels between dTIM and mTIM despite apparent functional divergence.
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Affiliation(s)
- Yao D Cai
- Department of Entomology and Nematology, College of Agricultural and Environmental Sciences, University of California Davis, CA, USA
| | - Joanna C Chiu
- Department of Entomology and Nematology, College of Agricultural and Environmental Sciences, University of California Davis, CA, USA
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15
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Kurogi Y, Mizuno Y, Imura E, Niwa R. Neuroendocrine Regulation of Reproductive Dormancy in the Fruit Fly Drosophila melanogaster: A Review of Juvenile Hormone-Dependent Regulation. Front Ecol Evol 2021. [DOI: 10.3389/fevo.2021.715029] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Animals can adjust their physiology, helping them survive and reproduce under a wide range of environmental conditions. One of the strategies to endure unfavorable environmental conditions such as low temperature and limited food supplies is dormancy. In some insect species, this may manifest as reproductive dormancy, which causes their reproductive organs to be severely depleted under conditions unsuitable for reproduction. Reproductive dormancy in insects is induced by a reduction in juvenile hormones synthesized in the corpus allatum (pl. corpora allata; CA) in response to winter-specific environmental cues, such as low temperatures and short-day length. In recent years, significant progress has been made in the study of dormancy-inducing conditions dependent on CA control mechanisms in Drosophila melanogaster. This review summarizes dormancy control mechanisms in D. melanogaster and discusses the implications for future studies of insect dormancy, particularly focusing on juvenile hormone-dependent regulation.
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16
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Anna G, Kannan NN. Post-transcriptional modulators and mediators of the circadian clock. Chronobiol Int 2021; 38:1244-1261. [PMID: 34056966 PMCID: PMC7611477 DOI: 10.1080/07420528.2021.1928159] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2021] [Revised: 04/26/2021] [Accepted: 05/03/2021] [Indexed: 01/04/2023]
Abstract
The endogenous circadian timekeeping system drives ~24-h rhythms in gene expression and rhythmically coordinates the physiology, metabolism and behavior in a wide range of organisms. Regulation at various levels is important for the accurate functioning of this circadian timing system. The core circadian oscillator consists of an interlocked transcriptional-translational negative feedback loop (TTFL) that imposes a substantial delay between the accumulation of clock gene mRNA and its protein to generate 24-h oscillations. This TTFL mediated daily oscillation of clock proteins is further fine-tuned by post-translational modifications that regulate the clock protein stability, interaction with other proteins and subcellular localization. Emerging evidence from various studies indicates that besides TTFL and post-translational modifications, post-transcriptional regulation plays a key role in shaping the rhythmicity of mRNAs and to delay the accumulation of clock proteins in relation to their mRNAs. In this review, we summarize the current knowledge on the importance of post-transcriptional regulatory mechanisms such as splicing, polyadenylation, the role of RNA-binding proteins, RNA methylation and microRNAs in the context of shaping the circadian rhythmicity in Drosophila and mammals. In particular, we discuss microRNAs, an important player in post-transcriptional regulation of core-clock machinery, circadian neural circuit, clock input, and output pathways. Furthermore, we provide an overview of the microRNAs that exhibit diurnal rhythm in expression and their role in mediating rhythmic physiological processes.
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Affiliation(s)
- Geo Anna
- Chronobiology Laboratory, School of Biology, Indian Institute of Science Education and Research (IISER), Thiruvananthapuram, Kerala 695551, India
| | - Nisha N Kannan
- Chronobiology Laboratory, School of Biology, Indian Institute of Science Education and Research (IISER), Thiruvananthapuram, Kerala 695551, India
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17
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George R, Stanewsky R. Peripheral Sensory Organs Contribute to Temperature Synchronization of the Circadian Clock in Drosophila melanogaster. Front Physiol 2021; 12:622545. [PMID: 33603678 PMCID: PMC7884628 DOI: 10.3389/fphys.2021.622545] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2020] [Accepted: 01/08/2021] [Indexed: 02/06/2023] Open
Abstract
Circadian clocks are cell-autonomous endogenous oscillators, generated and maintained by self-sustained 24-h rhythms of clock gene expression. In the fruit fly Drosophila melanogaster, these daily rhythms of gene expression regulate the activity of approximately 150 clock neurons in the fly brain, which are responsible for driving the daily rest/activity cycles of these insects. Despite their endogenous character, circadian clocks communicate with the environment in order to synchronize their self-sustained molecular oscillations and neuronal activity rhythms (internal time) with the daily changes of light and temperature dictated by the Earth's rotation around its axis (external time). Light and temperature changes are reliable time cues (Zeitgeber) used by many organisms to synchronize their circadian clock to the external time. In Drosophila, both light and temperature fluctuations robustly synchronize the circadian clock in the absence of the other Zeitgeber. The complex mechanisms for synchronization to the daily light-dark cycles are understood with impressive detail. In contrast, our knowledge about how the daily temperature fluctuations synchronize the fly clock is rather limited. Whereas light synchronization relies on peripheral and clock-cell autonomous photoreceptors, temperature input to the clock appears to rely mainly on sensory cells located in the peripheral nervous system of the fly. Recent studies suggest that sensory structures located in body and head appendages are able to detect temperature fluctuations and to signal this information to the brain clock. This review will summarize these studies and their implications about the mechanisms underlying temperature synchronization.
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Affiliation(s)
| | - Ralf Stanewsky
- Institute of Neuro- and Behavioral Biology, Westfälische Wilhelms-Universität Münster, Münster, Germany
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18
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Temperature-Dependent Alternative Splicing of Precursor mRNAs and Its Biological Significance: A Review Focused on Post-Transcriptional Regulation of a Cold Shock Protein Gene in Hibernating Mammals. Int J Mol Sci 2020; 21:ijms21207599. [PMID: 33066638 PMCID: PMC7590145 DOI: 10.3390/ijms21207599] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2020] [Revised: 10/12/2020] [Accepted: 10/13/2020] [Indexed: 01/18/2023] Open
Abstract
Multiple mRNA isoforms are often generated during processing such as alternative splicing of precursor mRNAs (pre-mRNA), resulting in a diversity of generated proteins. Alternative splicing is an essential mechanism for the functional complexity of eukaryotes. Temperature, which is involved in all life activities at various levels, is one of regulatory factors for controlling patterns of alternative splicing. Temperature-dependent alternative splicing is associated with various phenotypes such as flowering and circadian clock in plants and sex determination in poikilothermic animals. In some specific situations, temperature-dependent alternative splicing can be evoked even in homothermal animals. For example, the splicing pattern of mRNA for a cold shock protein, cold-inducible RNA-binding protein (CIRP or CIRBP), is changed in response to a marked drop in body temperature during hibernation of hamsters. In this review, we describe the current knowledge about mechanisms and functions of temperature-dependent alternative splicing in plants and animals. Then we discuss the physiological significance of hypothermia-induced alternative splicing of a cold shock protein gene in hibernating and non-hibernating animals.
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19
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EYES ABSENT and TIMELESS integrate photoperiodic and temperature cues to regulate seasonal physiology in Drosophila. Proc Natl Acad Sci U S A 2020; 117:15293-15304. [PMID: 32541062 PMCID: PMC7334534 DOI: 10.1073/pnas.2004262117] [Citation(s) in RCA: 36] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Extracting information regarding calendar time from seasonal changes in photoperiod and temperature is critical for organisms to maintain annual cycles in physiology and behavior. Here we found that, in flies, EYES ABSENT (EYA) protein acts as a seasonal sensor by adjusting its abundance and phase in response to changes in photoperiod and temperature. We show that the manipulation of EYA levels is sufficient to impair the ability of female Drosophila to regulate seasonal variation in reproductive dormancy. Finally, our results suggest an important role for the circadian clock protein TIMELESS (TIM) in modulating EYA level through its ability to measure night length, linking the circadian clock to seasonal timing. Organisms possess photoperiodic timing mechanisms to detect variations in day length and temperature as the seasons progress. The nature of the molecular mechanisms interpreting and signaling these environmental changes to elicit downstream neuroendocrine and physiological responses are just starting to emerge. Here, we demonstrate that, in Drosophila melanogaster, EYES ABSENT (EYA) acts as a seasonal sensor by interpreting photoperiodic and temperature changes to trigger appropriate physiological responses. We observed that tissue-specific genetic manipulation of eya expression is sufficient to disrupt the ability of flies to sense seasonal cues, thereby altering the extent of female reproductive dormancy. Specifically, we observed that EYA proteins, which peak at night in short photoperiod and accumulate at higher levels in the cold, promote reproductive dormancy in female D. melanogaster. Furthermore, we provide evidence indicating that the role of EYA in photoperiodism and temperature sensing is aided by the stabilizing action of the light-sensitive circadian clock protein TIMELESS (TIM). We postulate that increased stability and level of TIM at night under short photoperiod together with the production of cold-induced and light-insensitive TIM isoforms facilitate EYA accumulation in winter conditions. This is supported by our observations that tim null mutants exhibit reduced incidence of reproductive dormancy in simulated winter conditions, while flies overexpressing tim show an increased incidence of reproductive dormancy even in long photoperiod.
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20
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Martin Anduaga A, Evantal N, Patop IL, Bartok O, Weiss R, Kadener S. Thermosensitive alternative splicing senses and mediates temperature adaptation in Drosophila. eLife 2019; 8:44642. [PMID: 31702556 PMCID: PMC6890466 DOI: 10.7554/elife.44642] [Citation(s) in RCA: 44] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2018] [Accepted: 11/07/2019] [Indexed: 12/31/2022] Open
Abstract
Circadian rhythms are generated by the cyclic transcription, translation, and degradation of clock gene products, including timeless (tim), but how the circadian clock senses and adapts to temperature changes is not completely understood. Here, we show that temperature dramatically changes the splicing pattern of tim in Drosophila. We found that at 18°C, TIM levels are low because of the induction of two cold-specific isoforms: tim-cold and tim-short and cold. At 29°C, another isoform, tim-medium, is upregulated. Isoform switching regulates the levels and activity of TIM as each isoform has a specific function. We found that tim-short and cold encodes a protein that rescues the behavioral defects of tim01 mutants, and that flies in which tim-short and cold is abrogated have abnormal locomotor activity. In addition, miRNA-mediated control limits the expression of some of these isoforms. Finally, data that we obtained using minigenes suggest that tim alternative splicing might act as a thermometer for the circadian clock.
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Affiliation(s)
| | - Naveh Evantal
- Silberman Institute of Life Sciences, The Hebrew University of Jerusalem, Jerusalem, Israel
| | | | - Osnat Bartok
- Silberman Institute of Life Sciences, The Hebrew University of Jerusalem, Jerusalem, Israel
| | - Ron Weiss
- Silberman Institute of Life Sciences, The Hebrew University of Jerusalem, Jerusalem, Israel
| | - Sebastian Kadener
- Biology Department, Brandeis University, Waltham, United States.,Silberman Institute of Life Sciences, The Hebrew University of Jerusalem, Jerusalem, Israel
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