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Kulshrestha S, Devkar R. Circadian control of Nocturnin and its regulatory role in health and disease. Chronobiol Int 2023; 40:970-981. [PMID: 37400970 DOI: 10.1080/07420528.2023.2231081] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2023] [Revised: 06/01/2023] [Accepted: 06/24/2023] [Indexed: 07/05/2023]
Abstract
Circadian rhythms are generated by intrinsic 24-h oscillations that anticipate the extrinsic changes associated with solar day. A conserved transcriptional-translational feedback loop generates these molecular oscillations of clock genes at the organismal and the cellular levels. One of the recently discovered outputs of circadian clock is Nocturnin (Noct) or Ccrn4l. In mice, Noct mRNA is broadly expressed in cells throughout the body, with a particularly high-amplitude rhythm in liver. NOCT belongs to the EEP family of proteins with the closest similarity to the CCR4 family of deadenylases. Multiple studies have investigated the role of Nocturnin in development, adipogenesis, lipid metabolism, inflammation, osteogenesis, and obesity. Further, mice lacking Noct (Noct KO or Noct-/-) are protected from high-fat diet-induced obesity and hepatic steatosis. Recent studies had provided new insights by investigating various aspects of Nocturnin, ranging from its sub-cellular localization to identification of its target transcripts. However, a profound understanding of its molecular function remains elusive. This review article seeks to integrate the available literature into our current understanding of the functions of Nocturnin, their regulatory roles in key tissues and to throw light on the existing scientific lacunae.
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Affiliation(s)
- Shruti Kulshrestha
- Chronobiology and Molecular Endocrinology Lab, Department of Zoology, Faculty of Science, The Maharaja Sayajirao University of Baroda, Vadodara, India
| | - Ranjitsinh Devkar
- Chronobiology and Molecular Endocrinology Lab, Department of Zoology, Faculty of Science, The Maharaja Sayajirao University of Baroda, Vadodara, India
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2
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How RNases Shape Mitochondrial Transcriptomes. Int J Mol Sci 2022; 23:ijms23116141. [PMID: 35682820 PMCID: PMC9181182 DOI: 10.3390/ijms23116141] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2022] [Revised: 05/24/2022] [Accepted: 05/25/2022] [Indexed: 11/17/2022] Open
Abstract
Mitochondria are the power houses of eukaryote cells. These endosymbiotic organelles of prokaryote origin are considered as semi-autonomous since they have retained a genome and fully functional gene expression mechanisms. These pathways are particularly interesting because they combine features inherited from the bacterial ancestor of mitochondria with characteristics that appeared during eukaryote evolution. RNA biology is thus particularly diverse in mitochondria. It involves an unexpectedly vast array of factors, some of which being universal to all mitochondria and others being specific from specific eukaryote clades. Among them, ribonucleases are particularly prominent. They play pivotal functions such as the maturation of transcript ends, RNA degradation and surveillance functions that are required to attain the pool of mature RNAs required to synthesize essential mitochondrial proteins such as respiratory chain proteins. Beyond these functions, mitochondrial ribonucleases are also involved in the maintenance and replication of mitochondrial DNA, and even possibly in the biogenesis of mitochondrial ribosomes. The diversity of mitochondrial RNases is reviewed here, showing for instance how in some cases a bacterial-type enzyme was kept in some eukaryotes, while in other clades, eukaryote specific enzymes were recruited for the same function.
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3
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Wickramaratne AC, Li L, Hopkins JB, Joachimiak LA, Green CB. The Disordered Amino Terminus of the Circadian Enzyme Nocturnin Modulates Its NADP(H) Phosphatase Activity by Changing Protein Dynamics. Biochemistry 2022; 61:10.1021/acs.biochem.2c00072. [PMID: 35535990 PMCID: PMC9646931 DOI: 10.1021/acs.biochem.2c00072] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Endogenous circadian clocks control the rhythmicity of a broad range of behavioral and physiological processes, and this is entrained by the daily fluctuations in light and dark. Nocturnin (Noct) is a rhythmically expressed gene regulated by the circadian clock that belongs to the CCR4 family of endonuclease-exonuclease-phosphatase (EEP) enzymes, and the NOCT protein exhibits phosphatase activity, catalyzing the removal of the 2'-phosphate from NADP(H). In addition to its daily nighttime peak of expression, it is also induced by acute stimuli. Loss of Nocturnin (Noct-/-) in mice results in resistance to high-fat diet-induced obesity, and loss of Noct in HEK293T cells confers a protective effect to oxidative stress. Modeling of the full-length Nocturnin protein reveals a partially structured amino terminus that is disparate from its CCR4 family members. The high sequence conservation of a leucine zipper-like (LZ-like) motif, the only structural element in the amino terminus, highlights the potential importance of this domain in modulating phosphatase activity. In vitro biochemical and biophysical techniques demonstrate that the LZ-like domain within the flexible N-terminus is necessary for preserving the active site cleft in an optimal conformation to promote the efficient turnover of the substrate. This modulation occurs in cis and is pivotal in maintaining the stability and conformational integrity of the enzyme. These new findings suggest an additional layer of modulating the activity of Nocturnin in addition to its rhythmicity to provide fine-tuned control over cellular levels of NADPH.
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Affiliation(s)
- Anushka C. Wickramaratne
- Department of Neuroscience, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Li Li
- Center for Alzheimer’s and Neurodegenerative Diseases, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Jesse B. Hopkins
- Biophysics Collaborative Access Team, Illinois Institute of Technology, Advanced Photon Source, Argonne National Laboratory, Lemont, IL 60439, USA
| | - Lukasz A. Joachimiak
- Center for Alzheimer’s and Neurodegenerative Diseases, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
- Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Carla B. Green
- Department of Neuroscience, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
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Specificity and Mechanism of Coronavirus, Rotavirus, and Mammalian Two-Histidine Phosphoesterases That Antagonize Antiviral Innate Immunity. mBio 2021; 12:e0178121. [PMID: 34372695 PMCID: PMC8406329 DOI: 10.1128/mbio.01781-21] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
The 2′,5′-oligoadenylate (2-5A)-dependent endoribonuclease, RNase L, is a principal mediator of the interferon (IFN) antiviral response. Therefore, the regulation of cellular levels of 2-5A is a key point of control in antiviral innate immunity. Cellular 2-5A levels are determined by IFN-inducible 2′,5′-oligoadenylate synthetases (OASs) and by enzymes that degrade 2-5A. Importantly, many coronaviruses (CoVs) and rotaviruses encode 2-5A-degrading enzymes, thereby antagonizing RNase L and its antiviral effects. A-kinase-anchoring protein 7 (AKAP7), a mammalian counterpart, could possibly limit tissue damage from excessive or prolonged RNase L activation during viral infections or from self-double-stranded RNAs that activate OAS. We show that these enzymes, members of the two-histidine phosphoesterase (2H-PE) superfamily, constitute a subfamily referred here as 2′,5′-PEs. 2′,5′-PEs from the mouse CoV mouse hepatitis virus (MHV) (NS2), Middle East respiratory syndrome coronavirus (MERS-CoV) (NS4b), group A rotavirus (VP3), and mouse (AKAP7) were investigated for their evolutionary relationships and activities. While there was no activity against 3′,5′-oligoribonucleotides, they all cleaved 2′,5′-oligoadenylates efficiently but with variable activity against other 2′,5′-oligonucleotides. The 2′,5′-PEs are shown to be metal ion-independent enzymes that cleave trimer 2-5A (2′,5′-p3A3) producing mono- or diadenylates with 2′,3′-cyclic phosphate termini. Our results suggest that the elimination of 2-5A might be the sole function of viral 2′,5′-PEs, thereby promoting viral escape from innate immunity by preventing or limiting the activation of RNase L.
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Abshire ET, Hughes KL, Diao R, Pearce S, Gopalakrishna S, Trievel RC, Rorbach J, Freddolino PL, Goldstrohm AC. Differential processing and localization of human Nocturnin controls metabolism of mRNA and nicotinamide adenine dinucleotide cofactors. J Biol Chem 2020; 295:15112-15133. [PMID: 32839274 PMCID: PMC7606674 DOI: 10.1074/jbc.ra120.012618] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2020] [Revised: 08/06/2020] [Indexed: 01/02/2023] Open
Abstract
Nocturnin (NOCT) is a eukaryotic enzyme that belongs to a superfamily of exoribonucleases, endonucleases, and phosphatases. In this study, we analyze the expression, processing, localization, and cellular functions of human NOCT. We find that NOCT protein is differentially expressed and processed in a cell and tissue type-specific manner to control its localization to the cytoplasm or mitochondrial exterior or interior. The N terminus of NOCT is necessary and sufficient to confer import and processing in the mitochondria. We measured the impact of cytoplasmic NOCT on the transcriptome and observed that it affects mRNA levels of hundreds of genes that are significantly enriched in osteoblast, neuronal, and mitochondrial functions. Recent biochemical data indicate that NOCT dephosphorylates NADP(H) metabolites, and thus we measured the effect of NOCT on these cofactors in cells. We find that NOCT increases NAD(H) and decreases NADP(H) levels in a manner dependent on its intracellular localization. Collectively, our data indicate that NOCT can regulate levels of both mRNAs and NADP(H) cofactors in a manner specified by its location in cells.
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Affiliation(s)
- Elizabeth T Abshire
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, Minnesota, USA; Department of Biological Chemistry, University of Michigan Medical School, Ann Arbor, Michigan, USA
| | - Kelsey L Hughes
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, Minnesota, USA
| | - Rucheng Diao
- Department of Computational Medicine and Bioinformatics, University of Michigan Medical School, Ann Arbor, Michigan, USA
| | - Sarah Pearce
- Department of Medical Biochemistry and Biophysics, Division of Molecular Metabolism, Karolinska Institute, Solna, Sweden; Max Planck Institute Biology of Ageing - Karolinska Institute Laboratory, Karolinska Institute, Stockholm, Sweden
| | - Shreekara Gopalakrishna
- Department of Medical Biochemistry and Biophysics, Division of Molecular Metabolism, Karolinska Institute, Solna, Sweden
| | - Raymond C Trievel
- Department of Biological Chemistry, University of Michigan Medical School, Ann Arbor, Michigan, USA
| | - Joanna Rorbach
- Department of Medical Biochemistry and Biophysics, Division of Molecular Metabolism, Karolinska Institute, Solna, Sweden; Max Planck Institute Biology of Ageing - Karolinska Institute Laboratory, Karolinska Institute, Stockholm, Sweden
| | - Peter L Freddolino
- Department of Biological Chemistry, University of Michigan Medical School, Ann Arbor, Michigan, USA; Department of Computational Medicine and Bioinformatics, University of Michigan Medical School, Ann Arbor, Michigan, USA
| | - Aaron C Goldstrohm
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, Minnesota, USA.
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Beta RAA, Kyritsis A, Douka V, Papanastasi E, Rizouli M, Leonidas DD, Vlachakis D, Balatsos NAA. Biochemical and in silico identification of the active site and the catalytic mechanism of the circadian deadenylase HESPERIN. FEBS Open Bio 2020; 12:1036-1049. [PMID: 33095977 PMCID: PMC9063446 DOI: 10.1002/2211-5463.13011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2020] [Revised: 10/04/2020] [Accepted: 10/20/2020] [Indexed: 11/23/2022] Open
Abstract
The 24‐h molecular clock is based on the stability of rhythmically expressed transcripts. The shortening of the poly(A) tail of mRNAs is often the first and rate‐limiting step that determines the lifespan of a mRNA and is catalyzed by deadenylases. Herein, we determine the catalytic site of Hesperin, a recently described circadian deadenylase in plants, using a modified site‐directed mutagenesis protocol and a custom vector, pATHRA. To explore the catalytic efficiency of AtHESPERIN, we investigated the effect of AMP and neomycin, and used molecular modeling simulations to propose a catalytic mechanism. Collectively, the biochemical and in silico results classify AtHESPERIN in the exonuclease–endonuclease–phosphatase deadenylase superfamily and contribute to the understanding of the intricate mechanisms of circadian mRNA turnover.
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Affiliation(s)
- Rafailia A A Beta
- Department of Biochemistry and Biotechnology, University of Thessaly, Viopolis 415 00, Larissa, Greece
| | - Athanasios Kyritsis
- Department of Biochemistry and Biotechnology, University of Thessaly, Viopolis 415 00, Larissa, Greece.,Pulmonology Clinic, University Hospital of Larissa, Faculty of Medicine, University of Thessaly, Viopolis, 415 00, Larissa, Greece
| | - Veroniki Douka
- Department of Biochemistry and Biotechnology, University of Thessaly, Viopolis 415 00, Larissa, Greece
| | - Eirini Papanastasi
- Department of Biochemistry and Biotechnology, University of Thessaly, Viopolis 415 00, Larissa, Greece.,Department of Dermatology and Venereology, Lausanne University Hospital (CHUV), University of Lausanne, Switzerland
| | - Marianna Rizouli
- Department of Biochemistry and Biotechnology, University of Thessaly, Viopolis 415 00, Larissa, Greece
| | - Demetres D Leonidas
- Department of Biochemistry and Biotechnology, University of Thessaly, Viopolis 415 00, Larissa, Greece
| | - Dimitrios Vlachakis
- Genetics Laboratory, Department of Biotechnology, Agricultural University of Athens, 75 Iera Odos Street, 118 55, Athens, Greece
| | - Nikolaos A A Balatsos
- Department of Biochemistry and Biotechnology, University of Thessaly, Viopolis 415 00, Larissa, Greece
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7
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Spatiotemporal regulation of NADP(H) phosphatase Nocturnin and its role in oxidative stress response. Proc Natl Acad Sci U S A 2019; 117:993-999. [PMID: 31879354 DOI: 10.1073/pnas.1913712117] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
An intimate link exists between circadian clocks and metabolism with nearly every metabolic pathway in the mammalian liver under circadian control. Circadian regulation of metabolism is largely driven by rhythmic transcriptional activation of clock-controlled genes. Among these output genes, Nocturnin (Noct) has one of the highest amplitude rhythms at the mRNA level. The Noct gene encodes a protein (NOC) that is highly conserved with the endonuclease/exonuclease/phosphatase (EEP) domain-containing CCR4 family of deadenylases, but highly purified NOC possesses little or no ribonuclease activity. Here, we show that NOC utilizes the dinucleotide NADP(H) as a substrate, removing the 2' phosphate to generate NAD(H), and is a direct regulator of oxidative stress response through its NADPH 2' phosphatase activity. Furthermore, we describe two isoforms of NOC in the mouse liver. The cytoplasmic form of NOC is constitutively expressed and associates externally with membranes of other organelles, including the endoplasmic reticulum, via N-terminal glycine myristoylation. In contrast, the mitochondrial form of NOC possesses high-amplitude circadian rhythmicity with peak expression level during the early dark phase. These findings suggest that NOC regulates local intracellular concentrations of NADP(H) in a manner that changes over the course of the day.
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Estrella MA, Du J, Chen L, Rath S, Prangley E, Chitrakar A, Aoki T, Schedl P, Rabinowitz J, Korennykh A. The metabolites NADP + and NADPH are the targets of the circadian protein Nocturnin (Curled). Nat Commun 2019; 10:2367. [PMID: 31147539 PMCID: PMC6542800 DOI: 10.1038/s41467-019-10125-z] [Citation(s) in RCA: 36] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2019] [Accepted: 04/18/2019] [Indexed: 11/09/2022] Open
Abstract
Nocturnin (NOCT) is a rhythmically expressed protein that regulates metabolism under the control of circadian clock. It has been proposed that NOCT deadenylates and regulates metabolic enzyme mRNAs. However, in contrast to other deadenylases, purified NOCT lacks the deadenylase activity. To identify the substrate of NOCT, we conducted a mass spectrometry screen and report that NOCT specifically and directly converts the dinucleotide NADP+ into NAD+ and NADPH into NADH. Further, we demonstrate that the Drosophila NOCT ortholog, Curled, has the same enzymatic activity. We obtained the 2.7 Å crystal structure of the human NOCT•NADPH complex, which revealed that NOCT recognizes the chemically unique ribose-phosphate backbone of the metabolite, placing the 2′-terminal phosphate productively for removal. We provide evidence for NOCT targeting to mitochondria and propose that NADP(H) regulation, which takes place at least in part in mitochondria, establishes the molecular link between circadian clock and metabolism. Nocturnin is a rhythmically expressed protein that regulates metabolism under the control of circadian clock proposed to function through the deadenylation of metabolic enzyme mRNAs. Here the authors show that Nocturnin and its fly homolog Curled catalyze the removal of 2′-phosphate from NADP+ and NADPH, providing a direct link to metabolic regulation.
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Affiliation(s)
- Michael A Estrella
- 216 Schultz Laboratory, Department of Molecular Biology, Princeton, NJ, 08544, USA
| | - Jin Du
- 216 Schultz Laboratory, Department of Molecular Biology, Princeton, NJ, 08544, USA
| | - Li Chen
- 285 Frick Laboratory, Department of Chemistry, Princeton, NJ, 08544, USA.,Lewis-Sigler Institute for Integrative Genomics, Princeton, NJ, 08544, USA
| | - Sneha Rath
- 216 Schultz Laboratory, Department of Molecular Biology, Princeton, NJ, 08544, USA
| | - Eliza Prangley
- 216 Schultz Laboratory, Department of Molecular Biology, Princeton, NJ, 08544, USA
| | - Alisha Chitrakar
- 216 Schultz Laboratory, Department of Molecular Biology, Princeton, NJ, 08544, USA
| | - Tsutomu Aoki
- 216 Schultz Laboratory, Department of Molecular Biology, Princeton, NJ, 08544, USA
| | - Paul Schedl
- 216 Schultz Laboratory, Department of Molecular Biology, Princeton, NJ, 08544, USA
| | - Joshua Rabinowitz
- 285 Frick Laboratory, Department of Chemistry, Princeton, NJ, 08544, USA. .,Lewis-Sigler Institute for Integrative Genomics, Princeton, NJ, 08544, USA.
| | - Alexei Korennykh
- 216 Schultz Laboratory, Department of Molecular Biology, Princeton, NJ, 08544, USA.
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Le PT, Bornstein SA, Motyl KJ, Tian L, Stubblefield JJ, Hong HK, Takahashi JS, Green CB, Rosen CJ, Guntur AR. A novel mouse model overexpressing Nocturnin results in decreased fat mass in male mice. J Cell Physiol 2019; 234:20228-20239. [PMID: 30953371 DOI: 10.1002/jcp.28623] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2018] [Revised: 03/09/2019] [Accepted: 03/19/2019] [Indexed: 12/13/2022]
Abstract
Nocturnin (NOCT) belongs to the Mg2+ dependent Exonucleases, Endonucleases, Phosphatase (EEP) family of enzymes that exhibit various functions in vitro and in vivo. NOCT is known to function as a deadenylase, cleaving poly-A tails from mRNA (messenger RNA) transcripts. Previously, we reported a role for NOCT in regulating bone marrow stromal cell differentiation through its interactions with PPARγ. In this study, we characterized the skeletal and adipose tissue phenotype when we globally overexpressed Noct in vivo. After 12 weeks of Noct overexpression, transgenic male mice had lower fat mass compared to controls, with no significant differences in the skeleton. Based on the presence of a mitochondrial target sequence in NOCT, we determined that mouse NOCT protein localizes to the mitochondria; subsequently, we found that NOCT overexpression led to a significant increase in the preadipocytes ability to utilize oxidative phosphorylation for ATP (adenosine triphosphate) generation. In summary, the effects of NOCT on adipocytes are likely through its novel role as a mediator of mitochondrial function.
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Affiliation(s)
- Phuong T Le
- Center for Clinical and Translational Research, Maine Medical Center Research Institute, Scarborough, Maine
| | - Sheila A Bornstein
- Center for Clinical and Translational Research, Maine Medical Center Research Institute, Scarborough, Maine
| | - Katherine J Motyl
- Center for Molecular Medicine, Maine Medical Center Research Institute, Scarborough, Maine
| | - Li Tian
- Center for Molecular Medicine, Maine Medical Center Research Institute, Scarborough, Maine
| | - Jeremy J Stubblefield
- Department of Neuroscience, University of Texas Southwestern Medical Center, Dallas, Texas
| | - Hee-Kyung Hong
- Department of Medicine, Feinberg School of Medicine, Northwestern University, Chicago, Illinois
| | - Joseph S Takahashi
- Department of Neuroscience, University of Texas Southwestern Medical Center, Dallas, Texas.,Howard Hughes Medical Institute, University of Texas Southwestern Medical Center, Dallas, Texas
| | - Carla B Green
- Department of Neuroscience, University of Texas Southwestern Medical Center, Dallas, Texas
| | - Clifford J Rosen
- Center for Clinical and Translational Research, Maine Medical Center Research Institute, Scarborough, Maine.,Center for Molecular Medicine, Maine Medical Center Research Institute, Scarborough, Maine
| | - Anyonya R Guntur
- Center for Clinical and Translational Research, Maine Medical Center Research Institute, Scarborough, Maine.,Center for Molecular Medicine, Maine Medical Center Research Institute, Scarborough, Maine
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Hughes KL, Abshire ET, Goldstrohm AC. Regulatory roles of vertebrate Nocturnin: insights and remaining mysteries. RNA Biol 2018; 15:1255-1267. [PMID: 30257600 PMCID: PMC6284557 DOI: 10.1080/15476286.2018.1526541] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Post-transcriptional control of messenger RNA (mRNA) is an important layer of gene regulation that modulates mRNA decay, translation, and localization. Eukaryotic mRNA decay begins with the catalytic removal of the 3' poly-adenosine tail by deadenylase enzymes. Multiple deadenylases have been identified in vertebrates and are known to have distinct biological roles; among these proteins is Nocturnin, which has been linked to circadian biology, adipogenesis, osteogenesis, and obesity. Multiple studies have investigated Nocturnin's involvement in these processes; however, a full understanding of its molecular function remains elusive. Recent studies have provided new insights by identifying putative Nocturnin-regulated mRNAs in mice and by determining the structure and regulatory activities of human Nocturnin. This review seeks to integrate these new discoveries into our understanding of Nocturnin's regulatory functions and highlight the important remaining unanswered questions surrounding its regulation, biochemical activities, protein partners, and target mRNAs.
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Affiliation(s)
- Kelsey L Hughes
- a Department of Biochemistry, Molecular Biology and Biophysics , University of Minnesota , Minneapolis , MN , USA
| | - Elizabeth T Abshire
- a Department of Biochemistry, Molecular Biology and Biophysics , University of Minnesota , Minneapolis , MN , USA.,b Department of Biological Chemistry , University of Michigan , Ann Arbor , MI , USA
| | - Aaron C Goldstrohm
- a Department of Biochemistry, Molecular Biology and Biophysics , University of Minnesota , Minneapolis , MN , USA
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