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Biswas L, Tyc K, El Yakoubi W, Morgan K, Xing J, Schindler K. Meiosis interrupted: the genetics of female infertility via meiotic failure. Reproduction 2021; 161:R13-R35. [PMID: 33170803 DOI: 10.1530/rep-20-0422] [Citation(s) in RCA: 30] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2020] [Accepted: 11/10/2020] [Indexed: 12/14/2022]
Abstract
Idiopathic or 'unexplained' infertility represents as many as 30% of infertility cases worldwide. Conception, implantation, and term delivery of developmentally healthy infants require chromosomally normal (euploid) eggs and sperm. The crux of euploid egg production is error-free meiosis. Pathologic genetic variants dysregulate meiotic processes that occur during prophase I, meiotic resumption, chromosome segregation, and in cell cycle regulation. This dysregulation can result in chromosomally abnormal (aneuploid) eggs. In turn, egg aneuploidy leads to a broad range of clinical infertility phenotypes, including primary ovarian insufficiency and early menopause, egg fertilization failure and embryonic developmental arrest, or recurrent pregnancy loss. Therefore, maternal genetic variants are emerging as infertility biomarkers, which could allow informed reproductive decision-making. Here, we select and deeply examine human genetic variants that likely cause dysregulation of critical meiotic processes in 14 female infertility-associated genes: SYCP3, SYCE1, TRIP13, PSMC3IP, DMC1, MCM8, MCM9, STAG3, PATL2, TUBB8, CEP120, AURKB, AURKC, andWEE2. We discuss the function of each gene in meiosis, explore genotype-phenotype relationships, and delineate the frequencies of infertility-associated variants.
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Affiliation(s)
- Leelabati Biswas
- Department of Genetics, Rutgers, The State University of New Jersey, Piscataway, New Jersey, USA.,Human Genetics Institute of New Jersey, Rutgers, The State University of New Jersey, Piscataway, New Jersey, USA
| | - Katarzyna Tyc
- Department of Genetics, Rutgers, The State University of New Jersey, Piscataway, New Jersey, USA
| | - Warif El Yakoubi
- Department of Genetics, Rutgers, The State University of New Jersey, Piscataway, New Jersey, USA
| | - Katie Morgan
- Department of Genetics, Rutgers, The State University of New Jersey, Piscataway, New Jersey, USA
| | - Jinchuan Xing
- Department of Genetics, Rutgers, The State University of New Jersey, Piscataway, New Jersey, USA.,Human Genetics Institute of New Jersey, Rutgers, The State University of New Jersey, Piscataway, New Jersey, USA
| | - Karen Schindler
- Department of Genetics, Rutgers, The State University of New Jersey, Piscataway, New Jersey, USA.,Human Genetics Institute of New Jersey, Rutgers, The State University of New Jersey, Piscataway, New Jersey, USA
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2
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Maddirevula S, Coskun S, Alhassan S, Elnour A, Alsaif HS, Ibrahim N, Abdulwahab F, Arold ST, Alkuraya FS. Female Infertility Caused by Mutations in the Oocyte-Specific Translational Repressor PATL2. Am J Hum Genet 2017; 101:603-608. [PMID: 28965844 DOI: 10.1016/j.ajhg.2017.08.009] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2017] [Accepted: 08/11/2017] [Indexed: 12/23/2022] Open
Abstract
Infertility is a relatively common disorder of the reproductive system and remains unexplained in many cases. In vitro fertilization techniques have uncovered previously unrecognized infertility phenotypes, including oocyte maturation arrest, the molecular etiology of which remains largely unknown. We report two families affected by female-limited infertility caused by oocyte maturation failure. Positional mapping and whole-exome sequencing revealed two homozygous, likely deleterious variants in PATL2, each of which fully segregates with the phenotype within the respective family. PATL2 encodes a highly conserved oocyte-specific mRNP repressor of translation. Previous data have shown the strict requirement for PATL2 in oocyte-maturation in model organisms. Data gathered from the families in this study suggest that the role of PATL2 is conserved in humans and expand our knowledge of the factors that are necessary for female meiosis.
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Affiliation(s)
- Sateesh Maddirevula
- Department of Genetics, King Faisal Specialist Hospital and Research Center, Riyadh 11211, Saudi Arabia
| | - Serdar Coskun
- Department of Pathology and Laboratory Medicine, King Faisal Specialist Hospital and Research Center, Riyadh 11211, Saudi Arabia; College of Medicine, Alfaisal University, Riyadh, Saudi Arabia
| | - Saad Alhassan
- Department of Obstetrics and Gynecology, King Faisal Specialist Hospital and Research Center, Riyadh 11211, Saudi Arabia
| | - Atif Elnour
- Dr. Sulaiman Al Habib Medical Group, Olaya Complex, Riyadh 11643, Saudi Arabia
| | - Hessa S Alsaif
- Department of Genetics, King Faisal Specialist Hospital and Research Center, Riyadh 11211, Saudi Arabia
| | - Niema Ibrahim
- Department of Genetics, King Faisal Specialist Hospital and Research Center, Riyadh 11211, Saudi Arabia
| | - Firdous Abdulwahab
- Department of Genetics, King Faisal Specialist Hospital and Research Center, Riyadh 11211, Saudi Arabia
| | - Stefan T Arold
- King Abdullah University of Science and Technology, Computational Bioscience Research Center, Division of Biological and Environmental Sciences and Engineering, Thuwal 23955-6900, Saudi Arabia
| | - Fowzan S Alkuraya
- Department of Genetics, King Faisal Specialist Hospital and Research Center, Riyadh 11211, Saudi Arabia; Department of Anatomy and Cell Biology, College of Medicine, Alfaisal University, Riyadh 11533, Saudi Arabia; Saudi Human Genome Program, King Abdulaziz City for Science and Technology, Riyadh 11442, Saudi Arabia.
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3
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Nakamura Y, Iwasaki T, Umei Y, Saotome K, Nakajima Y, Kitahara S, Uno Y, Matsuda Y, Oike A, Kodama M, Nakamura M. Molecular cloning and characterization of oocyte-specific Pat1a in Rana rugosa frogs. ACTA ACUST UNITED AC 2015; 323:516-26. [PMID: 26136381 DOI: 10.1002/jez.1938] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2015] [Revised: 04/08/2015] [Accepted: 04/09/2015] [Indexed: 11/07/2022]
Abstract
The Pat1 gene is expressed in the immature oocytes of Xenopus, and is reportedly involved in regulating the translation of maternal mRNAs required for oocyte-maturation. However, it is still unknown when Pat1a first appears in the differentiating ovary of amphibians. To address this issue, we isolated the full-length Pat1a cDNA from the frog Rana rugosa and examined its expression in the differentiating ovary of this frog. Among eight different tissues examined, the Pat1a mRNA was detectable in only the ovary. When frozen sections from the ovaries of tadpoles at various stages of development were immunostained for Vasa-a germ cell-specific protein-and Pat1a, Vasa-immunopositive signals were observed in all of the germ cells, whereas Pat1a signals were confined to the growing oocytes (50-200 μm in diameter), and absent from small germ cells (<50 μm in diameter). Forty days after testosterone injection into tadpoles to induce female-to-male sex-reversal, Pat1a-immunoreactive oocytes had disappeared completely from the sex-reversed gonad, but Vasa-positive small germ cells persisted. Thus, Pat1a would be a good marker for identifying the sexual status of the sex-reversing gonad in amphibians. In addition, fluorescence in situ hybridization analysis showed Pat1a to have an autosomal locus, suggesting that Pat1a transcription is probably regulated by a tissue-specific transcription factor in R. rugosa.
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Affiliation(s)
- Yoriko Nakamura
- Department of Science Education, Faculty of Education, Ehime University, Matsuyama, Ehime, Japan.,Department of Biology, Faculty of Education and Integrated Arts and Sciences, Waseda University, Wakamatsu-cho, Tokyo, Japan
| | - Takehiro Iwasaki
- Department of Biology, Faculty of Education and Integrated Arts and Sciences, Waseda University, Wakamatsu-cho, Tokyo, Japan
| | - Yosuke Umei
- Department of Biology, Faculty of Education and Integrated Arts and Sciences, Waseda University, Wakamatsu-cho, Tokyo, Japan
| | - Kazuhiro Saotome
- Department of Biology, Faculty of Education and Integrated Arts and Sciences, Waseda University, Wakamatsu-cho, Tokyo, Japan
| | - Yukiko Nakajima
- Department of Biology, Faculty of Education and Integrated Arts and Sciences, Waseda University, Wakamatsu-cho, Tokyo, Japan
| | - Shoichi Kitahara
- Department of Biology, Faculty of Education and Integrated Arts and Sciences, Waseda University, Wakamatsu-cho, Tokyo, Japan
| | - Yoshinobu Uno
- Laboratory of Animal Genetics, Department of Applied Molecular Biosciences, Graduate School of Bioagricultural Science, Nagoya University, Furo-cho, Nagoya, Japan
| | - Yoichi Matsuda
- Laboratory of Animal Genetics, Department of Applied Molecular Biosciences, Graduate School of Bioagricultural Science, Nagoya University, Furo-cho, Nagoya, Japan
| | - Akira Oike
- Department of Biology, Faculty of Education and Integrated Arts and Sciences, Waseda University, Wakamatsu-cho, Tokyo, Japan
| | - Maho Kodama
- Department of Biology, Faculty of Education and Integrated Arts and Sciences, Waseda University, Wakamatsu-cho, Tokyo, Japan
| | - Masahisa Nakamura
- Department of Biology, Faculty of Education and Integrated Arts and Sciences, Waseda University, Wakamatsu-cho, Tokyo, Japan
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4
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Chowdhury A, Kalurupalle S, Tharun S. Pat1 contributes to the RNA binding activity of the Lsm1-7-Pat1 complex. RNA (NEW YORK, N.Y.) 2014; 20:1465-75. [PMID: 25035297 PMCID: PMC4138329 DOI: 10.1261/rna.045252.114] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/13/2014] [Accepted: 06/03/2014] [Indexed: 05/20/2023]
Abstract
A major mRNA decay pathway in eukaryotes is initiated by deadenylation followed by decapping of the oligoadenylated mRNAs and subsequent 5'-to-3' exonucleolytic degradation of the capless mRNA. In this pathway, decapping is a rate-limiting step that requires the hetero-octameric Lsm1-7-Pat1 complex to occur at normal rates in vivo. This complex is made up of the seven Sm-like proteins, Lsm1 through Lsm7, and the Pat1 protein. It binds RNA and has a unique binding preference for oligoadenylated RNAs over polyadenylated RNAs. Such binding ability is crucial for its mRNA decay function in vivo. In order to determine the contribution of Pat1 to the function of the Lsm1-7-Pat1 complex, we compared the RNA binding properties of the Lsm1-7 complex purified from pat1Δ cells and purified Pat1 fragments with that of the wild-type Lsm1-7-Pat1 complex. Our studies revealed that both the Lsm1-7 complex and purified Pat1 fragments have very low RNA binding activity and are impaired in the ability to recognize the oligo(A) tail on the RNA. However, reconstitution of the Lsm1-7-Pat1 complex from these components restored these abilities. We also observed that Pat1 directly contacts RNA in the context of the Lsm1-7-Pat1 complex. These studies suggest that the unique RNA binding properties and the mRNA decay function of the Lsm1-7-Pat1 complex involve cooperation of residues from both Pat1 and the Lsm1-7 ring. Finally our studies also revealed that the middle domain of Pat1 is essential for the interaction of Pat1 with the Lsm1-7 complex in vivo.
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Affiliation(s)
- Ashis Chowdhury
- Department of Biochemistry, Uniformed Services University of the Health Sciences, Bethesda, Maryland 20814, USA
| | - Swathi Kalurupalle
- Department of Biochemistry, Uniformed Services University of the Health Sciences, Bethesda, Maryland 20814, USA
| | - Sundaresan Tharun
- Department of Biochemistry, Uniformed Services University of the Health Sciences, Bethesda, Maryland 20814, USA
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5
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The C-terminal domain from S. cerevisiae Pat1 displays two conserved regions involved in decapping factor recruitment. PLoS One 2014; 9:e96828. [PMID: 24830408 PMCID: PMC4022514 DOI: 10.1371/journal.pone.0096828] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2014] [Accepted: 04/11/2014] [Indexed: 12/03/2022] Open
Abstract
Eukaryotic mRNA decay is a highly regulated process allowing cells to rapidly modulate protein production in response to internal and environmental cues. Mature translatable eukaryotic mRNAs are protected from fast and uncontrolled degradation in the cytoplasm by two cis-acting stability determinants: a methylguanosine (m7G) cap and a poly(A) tail at their 5′ and 3′ extremities, respectively. The hydrolysis of the m7G cap structure, known as decapping, is performed by the complex composed of the Dcp2 catalytic subunit and its partner Dcp1. The Dcp1-Dcp2 decapping complex has a low intrinsic activity and requires accessory factors to be fully active. Among these factors, Pat1 is considered to be a central scaffolding protein involved in Dcp2 activation but also in inhibition of translation initiation. Here, we present the structural and functional study of the C-terminal domain from S. cerevisiae Pat1 protein. We have identified two conserved and functionally important regions located at both extremities of the domain. The first region is involved in binding to Lsm1-7 complex. The second patch is specific for fungal proteins and is responsible for Pat1 interaction with Edc3. These observations support the plasticity of the protein interaction network involved in mRNA decay and show that evolution has extended the C-terminal alpha-helical domain from fungal Pat1 proteins to generate a new binding platform for protein partners.
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6
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The discovery and analysis of P Bodies. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2013; 768:23-43. [PMID: 23224963 DOI: 10.1007/978-1-4614-5107-5_3] [Citation(s) in RCA: 70] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
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7
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Pat1 proteins: a life in translation, translation repression and mRNA decay. Biochem Soc Trans 2011; 38:1602-7. [PMID: 21118134 DOI: 10.1042/bst0381602] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Pat1 proteins are conserved across eukaryotes. Vertebrates have evolved two Pat1 proteins paralogues, whereas invertebrates and yeast only possess one such protein. Despite their lack of known domains or motifs, Pat1 proteins are involved in several key post-transcriptional mechanisms of gene expression control. In yeast, Pat1p interacts with translating mRNPs (messenger ribonucleoproteins), and is responsible for translational repression and decapping activation, ultimately leading to mRNP degradation. Drosophila HPat and human Pat1b (PatL1) proteins also have conserved roles in the 5'→3' mRNA decay pathway. Consistent with their functions in silencing gene expression, Pat1 proteins localize to P-bodies (processing bodies) in yeast, Drosophila, Caenorhabditis elegans and human cells. Altogether, Pat1 proteins may act as scaffold proteins allowing the sequential binding of repression and decay factors on mRNPs, eventually leading to their degradation. In the present mini-review, we present the current knowledge on Pat1 proteins in the context of their multiple functions in post-transcriptional control.
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8
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Marnef A, Maldonado M, Bugaut A, Balasubramanian S, Kress M, Weil D, Standart N. Distinct functions of maternal and somatic Pat1 protein paralogs. RNA (NEW YORK, N.Y.) 2010; 16:2094-107. [PMID: 20826699 PMCID: PMC2957050 DOI: 10.1261/rna.2295410] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Abstract
We previously identified Xenopus Pat1a (P100) as a member of the maternal CPEB RNP complex, whose components resemble those of P-(rocessing) bodies, and which is implicated in translational control in Xenopus oocytes. Database searches have identified Pat1a proteins in other vertebrates, as well as paralogous Pat1b proteins. Here we characterize Pat1 proteins, which have no readily discernable sequence features, in Xenopus oocytes, eggs, and early embryos and in human tissue culture cells. xPat1a and 1b have essentially mutually exclusive expression patterns in oogenesis and embryogenesis. xPat1a is degraded during meiotic maturation, via PEST-like regions, while xPat1b mRNA is translationally activated at GVBD by cytoplasmic polyadenylation. Pat1 proteins bind RNA in vitro, via a central domain, with a preference for G-rich sequences, including the NRAS 5' UTR G-quadruplex-forming sequence. When tethered to reporter mRNA, both Pat proteins repress translation in oocytes. Indeed, both epitope-tagged proteins interact with the same components of the CPEB RNP complex, including CPEB, Xp54, eIF4E1b, Rap55B, and ePAB. However, examining endogenous protein interactions, we find that in oocytes only xPat1a is a bona fide component of the CPEB RNP, and that xPat1b resides in a separate large complex. In tissue culture cells, hPat1b localizes to P-bodies, while mPat1a-GFP is either found weakly in P-bodies or disperses P-bodies in a dominant-negative fashion. Altogether we conclude that Pat1a and Pat1b proteins have distinct functions, mediated in separate complexes. Pat1a is a translational repressor in oocytes in a CPEB-containing complex, and Pat1b is a component of P-bodies in somatic cells.
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Affiliation(s)
- Aline Marnef
- Department of Biochemistry, University of Cambridge, Cambridge CB21QW, United Kingdom
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9
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Nakamura Y, Tanaka KJ, Miyauchi M, Huang L, Tsujimoto M, Matsumoto K. Translational repression by the oocyte-specific protein P100 in Xenopus. Dev Biol 2010; 344:272-83. [PMID: 20471969 DOI: 10.1016/j.ydbio.2010.05.006] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2009] [Revised: 04/09/2010] [Accepted: 05/07/2010] [Indexed: 01/10/2023]
Abstract
The translational regulation of maternal mRNAs is one of the most important steps in the control of temporal-spatial gene expression during oocyte maturation and early embryogenesis in various species. Recently, it has become clear that protein components of mRNPs play essential roles in the translational regulation of maternal mRNAs. In the present study, we investigated the function of P100 in Xenopus oocytes. P100 exhibits sequence conservation with budding yeast Pat1 and is likely the orthologue of human Pat1a (also called PatL2). P100 is maternally expressed in immature oocytes, but disappears during oocyte maturation. In oocytes, P100 is an RNA binding component of ribosome-free mRNPs, associating with other mRNP components such as Xp54, xRAP55 and CPEB. Translational repression by overexpression of P100 occurred when reporter mRNAs were injected into oocytes. Intriguingly, we found that when P100 was overexpressed in the oocytes, the kinetics of oocyte maturation was considerably retarded. In addition, overexpression of P100 in oocytes significantly affected the accumulation of c-Mos and cyclin B1 during oocyte maturation. These results suggest that P100 plays a role in regulating the translation of specific maternal mRNAs required for the progression of Xenopus oocyte maturation.
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Affiliation(s)
- Yoriko Nakamura
- Laboratory of Cellular Biochemistry, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan
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10
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Pat1 contains distinct functional domains that promote P-body assembly and activation of decapping. Mol Cell Biol 2007; 28:1298-312. [PMID: 18086885 DOI: 10.1128/mcb.00936-07] [Citation(s) in RCA: 97] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The control of mRNA degradation and translation are important aspects of gene regulation. Recent results suggest that translation repression and mRNA decapping can be intertwined and involve the formation of a quiescent mRNP, which can accumulate in cytoplasmic foci referred to as P bodies. The Pat1 protein is a key component of this complex and an important activator of decapping, yet little is known about its function. In this work, we analyze Pat1 in Saccharomyces cerevisiae function by deletion and functional analyses. Our results identify two primary functional domains in Pat1: one promoting translation repression and P-body assembly and a second domain promoting mRNA decapping after assembly of the mRNA into a P-body mRNP. In addition, we provide evidence that Pat1 binds RNA and has numerous domain-specific interactions with mRNA decapping factors. These results indicate that Pat1 is an RNA binding protein and a multidomain protein that functions at multiple stages in the process of translation repression and mRNA decapping.
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11
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Minshall N, Reiter MH, Weil D, Standart N. CPEB Interacts with an Ovary-specific eIF4E and 4E-T in Early Xenopus Oocytes. J Biol Chem 2007; 282:37389-401. [PMID: 17942399 DOI: 10.1074/jbc.m704629200] [Citation(s) in RCA: 138] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Affiliation(s)
- Nicola Minshall
- Department of Biochemistry, University of Cambridge, Cambridge, UK
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12
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Scheller N, Resa-Infante P, de la Luna S, Galao RP, Albrecht M, Kaestner L, Lipp P, Lengauer T, Meyerhans A, Díez J. Identification of PatL1, a human homolog to yeast P body component Pat1. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2007; 1773:1786-92. [PMID: 17936923 DOI: 10.1016/j.bbamcr.2007.08.009] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/17/2007] [Revised: 08/23/2007] [Accepted: 08/24/2007] [Indexed: 11/29/2022]
Abstract
In yeast, the activators of mRNA decapping, Pat1, Lsm1 and Dhh1, accumulate in processing bodies (P bodies) together with other proteins of the 5'-3'-deadenylation-dependent mRNA decay pathway. The Pat1 protein is of particular interest because it functions in the opposing processes of mRNA translation and mRNA degradation, thus suggesting an important regulatory role. In contrast to other components of this mRNA decay pathway, the human homolog of the yeast Pat1 protein was unknown. Here we describe the identification of two human PAT1 genes and show that one of them, PATL1, codes for an ORF with similar features as the yeast PAT1. As expected for a protein with a fundamental role in translation control, PATL1 mRNA was ubiquitously expressed in all human tissues as were the mRNAs of LSM1 and RCK, the human homologs of yeast LSM1 and DHH1, respectively. Furthermore, fluorescence-tagged PatL1 protein accumulated in distinct foci that correspond to P bodies, as they co-localized with the P body components Lsm1, Rck/p54 and the decapping enzyme Dcp1. In addition, as for its yeast counterpart, PatL1 expression was required for P body formation. Taken together, these data emphasize the conservation of important P body components from yeast to human cells.
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13
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Abstract
The targeting of messenger RNAs (mRNAs) to specific subcellular sites for local translation plays an important role in diverse cellular and developmental processes in eukaryotes, including axis formation, cell fate determination, spindle pole regulation, cell motility, and neuronal synaptic plasticity. Recently, a new conserved class of Lsm proteins, the Scd6 family, has been implicated in controlling mRNA function. Depletion or mutation of members of the Scd6 family, Caenorhabditis elegans CAR-1 and Drosophila melanogaster trailer hitch, lead to a variety of developmental phenotypes, which in some cases can be linked to alterations in the endoplasmic reticulum (ER). Scd6/Lsm proteins are RNA binding proteins and are found in RNP complexes associated with translational control of mRNAs, and these complexes can colocalize with the ER. These findings raise the possibility that localization and translational regulation of mRNAs at the ER plays a role in controlling the organization of this organelle.
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Affiliation(s)
- Carolyn J Decker
- Department of Molecular and Cellular Biology and Howard Hughes Medical Institute, University of Arizona, Tucson, 85721, USA
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14
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Coller J, Parker R. General translational repression by activators of mRNA decapping. Cell 2005; 122:875-86. [PMID: 16179257 PMCID: PMC1853273 DOI: 10.1016/j.cell.2005.07.012] [Citation(s) in RCA: 488] [Impact Index Per Article: 25.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2005] [Revised: 06/22/2005] [Accepted: 07/13/2005] [Indexed: 12/24/2022]
Abstract
Translation and mRNA degradation are affected by a key transition where eukaryotic mRNAs exit translation and assemble an mRNP state that accumulates into processing bodies (P bodies), cytoplasmic sites of mRNA degradation containing non-translating mRNAs, and mRNA degradation machinery. We identify the decapping activators Dhh1p and Pat1p as functioning as translational repressors and facilitators of P body formation. Strains lacking both Dhh1p and Pat1p show strong defects in mRNA decapping and P body formation and are blocked in translational repression. Contrastingly, overexpression of Dhh1p or Pat1p causes translational repression, P body formation, and arrests cell growth. Dhh1p, and its human homolog, RCK/p54, repress translation in vitro, and Dhh1p function is bypassed in vivo by inhibition of translational initiation. These results identify a broadly acting mechanism of translational repression that targets mRNAs for decapping and functions in translational control. We propose this mechanism is competitively balanced with translation, and shifting this balance is an important basis of translational control.
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Affiliation(s)
- Jeff Coller
- Howard Hughes Medical Institute, Department of Molecular and Cellular Biology University of Arizona Tucson, Arizona 85721
| | - Roy Parker
- Howard Hughes Medical Institute, Department of Molecular and Cellular Biology University of Arizona Tucson, Arizona 85721
- *Correspondence:
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15
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Schwartz DC, Parker R. mRNA decapping in yeast requires dissociation of the cap binding protein, eukaryotic translation initiation factor 4E. Mol Cell Biol 2000; 20:7933-42. [PMID: 11027264 PMCID: PMC86404 DOI: 10.1128/mcb.20.21.7933-7942.2000] [Citation(s) in RCA: 140] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
A major pathway of eukaryotic mRNA turnover occurs by deadenylation-dependent decapping that exposes the transcript to 5'-->3' exonucleolytic degradation. A critical step in this pathway is decapping, since removal of the cap structure permits 5'-->3' exonucleolytic digestion. Based on alterations in mRNA decay rate from strains deficient in translation initiation, it has been proposed that the decapping rate is modulated by a competition between the cytoplasmic cap binding complex, which promotes translation initiation, and the decapping enzyme, Dcp1p. In order to test this model directly, we examined the functional interaction of Dcp1p and the cap binding protein, eukaryotic translation initiation factor 4E (eIF4E), in vitro. These experiments indicated that eIF4E is an inhibitor of Dcp1p in vitro due to its ability to bind the 5' cap structure. In addition, we demonstrate that in vivo a temperature-sensitive allele of eIF4E (cdc33-42) suppressed the decapping defect of a partial loss-of-function allele of DCP1. These results argue that dissociation of eIF4E from the cap structure is required before decapping. Interestingly, the temperature-sensitive allele of eIF4E does not suppress the decapping defect seen in strains lacking the decapping activators, Lsm1p and Pat1p. This indicates that these activators of decapping affect a step in mRNA turnover distinct from the competition between Dcp1 and eIF4E.
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Affiliation(s)
- D C Schwartz
- Department of Molecular and Cellular Biology, University of Arizona, Tucson, Arizona 85721, USA
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16
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Bonnerot C, Boeck R, Lapeyre B. The two proteins Pat1p (Mrt1p) and Spb8p interact in vivo, are required for mRNA decay, and are functionally linked to Pab1p. Mol Cell Biol 2000; 20:5939-46. [PMID: 10913177 PMCID: PMC86071 DOI: 10.1128/mcb.20.16.5939-5946.2000] [Citation(s) in RCA: 120] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
We report here the characterization of a bypass suppressor of pab1Delta which leads to a fourfold stabilization of the unstable MFA2 mRNA. Cloning of the wild-type gene for that suppressor reveals that it is identical to PAT1 (YCR077c), a gene whose product was reported to interact with Top2p. PAT1 is not an essential gene, but its deletion leads to a thermosensitive phenotype. Further analysis has shown that PAT1 is allelic with mrt1-3, a mutation previously reported to affect decapping and to bypass suppress pab1Delta, as is also the case for dcp1, spb8, and mrt3. Coimmunoprecipitation experiments show that Pat1p is associated with Spb8p. On sucrose gradients, the two proteins cosediment with fractions containing the polysomes. In the absence of Pat1p, however, Spb8p no longer cofractionates with the polysomes, while the removal of Spb8p leads to a sharp decrease in the level of Pat1p. Our results suggest that some of the factors involved in mRNA degradation could be associated with the mRNA that is still being translated, awaiting a specific signal to commit the mRNA to the degradation pathway.
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Affiliation(s)
- C Bonnerot
- Centre de Recherche de Biochimie Macromoléculaire du CNRS, 34293 Montpellier, France.
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Bouveret E, Rigaut G, Shevchenko A, Wilm M, Séraphin B. A Sm-like protein complex that participates in mRNA degradation. EMBO J 2000; 19:1661-71. [PMID: 10747033 PMCID: PMC310234 DOI: 10.1093/emboj/19.7.1661] [Citation(s) in RCA: 298] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
In eukaryotes, seven Sm proteins bind to the U1, U2, U4 and U5 spliceosomal snRNAs while seven Smlike proteins (Lsm2p-Lsm8p) are associated with U6 snRNA. Another yeast Sm-like protein, Lsm1p, does not interact with U6 snRNA. Surprisingly, using the tandem affinity purification (TAP) method, we identified Lsm1p among the subunits associated with Lsm3p. Coprecipitation experiments demonstrated that Lsm1p, together with Lsm2p-Lsm7p, forms a new seven-subunit complex. We purified the two related Sm-like protein complexes and identified the proteins recovered in the purified preparations by mass spectrometry. This confirmed the association of the Lsm2p-Lsm8p complex with U6 snRNA. In contrast, the Lsm1p-Lsm7p complex is associated with Pat1p and Xrn1p exoribonuclease, suggesting a role in mRNA degradation. Deletions of LSM1, 6, 7 and PAT1 genes increased the half-life of reporter mRNAs. Interestingly, accumulating mRNAs were capped, suggesting a block in mRNA decay at the decapping step. These results indicate the involvement of a new conserved Sm-like protein complex and a new factor, Pat1p, in mRNA degradation and suggest a physical connection between decapping and exonuclease trimming.
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MESH Headings
- Codon, Nonsense/genetics
- Fungal Proteins/chemistry
- Fungal Proteins/genetics
- Fungal Proteins/metabolism
- Gene Deletion
- Genes, Fungal
- Genes, Reporter
- Macromolecular Substances
- RNA Caps/genetics
- RNA Caps/metabolism
- RNA, Fungal/genetics
- RNA, Fungal/metabolism
- RNA, Messenger/genetics
- RNA, Messenger/metabolism
- Ribonucleoproteins, Small Nuclear/chemistry
- Ribonucleoproteins, Small Nuclear/genetics
- Ribonucleoproteins, Small Nuclear/metabolism
- Saccharomyces cerevisiae/genetics
- Saccharomyces cerevisiae/metabolism
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Affiliation(s)
- E Bouveret
- EMBL, Meyerhofstrasse-1, D-69117 Heidelberg, Germany
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18
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Wang X, Watt PM, Louis EJ, Borts RH, Hickson ID. Pat1: a topoisomerase II-associated protein required for faithful chromosome transmission in Saccharomyces cerevisiae. Nucleic Acids Res 1996; 24:4791-7. [PMID: 8972867 PMCID: PMC146302 DOI: 10.1093/nar/24.23.4791] [Citation(s) in RCA: 52] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
Saccharomyces cerevisiae top2 mutants deficient in topoisomerase II activity are defective in chromosome segregation during both mitotic and meiotic cell divisions. To identify proteins that act in concert with topoisomerase II during chromosome segregation in S.cerevisiae, we have used a two-hybrid cloning approach. We report the isolation of the PAT1 gene (for protein associated with topoisomerase II), which encodes a novel 90 kDa proline- and glutamine-rich protein that interacts with a highly conserved, leucine-rich region of topoisomerase II in vivo. Strains lacking Pat1p exhibit a slow growth rate and a phenotype reminiscent of conditional top2 mutants grown at the semi-permissive temperature; most notably, a reduced fidelity of chromosome segregation during both mitosis and meiosis. These findings indicate that the PAT1 gene is necessary for accurate chromosome transmission during cell division in eukaryotic cells and suggest that the interaction of Pat1p and topoisomerase II is an important component of this function.
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Affiliation(s)
- X Wang
- Institute of Molecular Medicine, John Radcliffe Hospital, Oxford, UK
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