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Emond-Fraser V, Larouche M, Kubiniok P, Bonneil É, Li J, Bourouh M, Frizzi L, Thibault P, Archambault V. Identification of PP2A-B55 targets uncovers regulation of emerin during nuclear envelope reassembly in Drosophila. Open Biol 2023; 13:230104. [PMID: 37463656 PMCID: PMC10353892 DOI: 10.1098/rsob.230104] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2023] [Accepted: 06/21/2023] [Indexed: 07/20/2023] Open
Abstract
Mitotic exit requires the dephosphorylation of many proteins whose phosphorylation was needed for mitosis. Protein phosphatase 2A with its B55 regulatory subunit (PP2A-B55) promotes this transition. However, the events and substrates that it regulates are incompletely understood. We used proteomic approaches in Drosophila to identify proteins that interact with and are dephosphorylated by PP2A-B55. Among several candidates, we identified emerin (otefin in Drosophila). Emerin resides in the inner nuclear membrane and interacts with the DNA-binding protein barrier-to-autointegration factor (BAF) via a LEM domain. We found that the phosphorylation of emerin at Ser50 and Ser54 near its LEM domain negatively regulates its association with BAF, lamin and additional emerin in mitosis. We show that dephosphorylation of emerin at these sites by PP2A-B55 determines the timing of nuclear envelope reformation. Genetic experiments indicate that this regulation is required during embryonic development. Phosphoregulation of the emerin-BAF complex formation by PP2A-B55 appears as a key event of mitotic exit that is likely conserved across species.
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Affiliation(s)
- Virginie Emond-Fraser
- Institute for Research in Immunology and Cancer, Université de Montréal, Montréal, H3T 1J4, Quebec, Canada
- Département de biochimie et médecine moléculaire, Université de Montréal, Montréal, H3T 1J4, Quebec, Canada
| | - Myreille Larouche
- Institute for Research in Immunology and Cancer, Université de Montréal, Montréal, H3T 1J4, Quebec, Canada
- Département de biochimie et médecine moléculaire, Université de Montréal, Montréal, H3T 1J4, Quebec, Canada
| | - Peter Kubiniok
- Institute for Research in Immunology and Cancer, Université de Montréal, Montréal, H3T 1J4, Quebec, Canada
| | - Éric Bonneil
- Institute for Research in Immunology and Cancer, Université de Montréal, Montréal, H3T 1J4, Quebec, Canada
| | - Jingjing Li
- Institute for Research in Immunology and Cancer, Université de Montréal, Montréal, H3T 1J4, Quebec, Canada
| | - Mohammed Bourouh
- Institute for Research in Immunology and Cancer, Université de Montréal, Montréal, H3T 1J4, Quebec, Canada
| | - Laura Frizzi
- Institute for Research in Immunology and Cancer, Université de Montréal, Montréal, H3T 1J4, Quebec, Canada
- Département de biochimie et médecine moléculaire, Université de Montréal, Montréal, H3T 1J4, Quebec, Canada
| | - Pierre Thibault
- Institute for Research in Immunology and Cancer, Université de Montréal, Montréal, H3T 1J4, Quebec, Canada
- Département de chimie, Université de Montréal, Montréal, H3T 1J4, Quebec, Canada
| | - Vincent Archambault
- Institute for Research in Immunology and Cancer, Université de Montréal, Montréal, H3T 1J4, Quebec, Canada
- Département de biochimie et médecine moléculaire, Université de Montréal, Montréal, H3T 1J4, Quebec, Canada
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Duan T, Thyagarajan S, Amoiroglou A, Rogers GC, Geyer PK. Analysis of a rare progeria variant of Barrier-to-autointegration factor in Drosophila connects centromere function to tissue homeostasis. Cell Mol Life Sci 2023; 80:73. [PMID: 36842139 DOI: 10.1007/s00018-023-04721-y] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2022] [Revised: 02/05/2023] [Accepted: 02/07/2023] [Indexed: 02/27/2023]
Abstract
Barrier-to-autointegration factor (BAF/BANF) is a nuclear lamina protein essential for nuclear integrity, chromatin structure, and genome stability. Whereas complete loss of BAF causes lethality in multiple organisms, the A12T missense mutation of the BANF1 gene in humans causes a premature aging syndrome, called Néstor-Guillermo Progeria Syndrome (NGPS). Here, we report the first in vivo animal investigation of progeroid BAF, using CRISPR editing to introduce the NGPS mutation into the endogenous Drosophila baf gene. Progeroid BAF adults are born at expected frequencies, demonstrating that this BAF variant retains some function. However, tissue homeostasis is affected, supported by studies of the ovary, a tissue that depends upon BAF for stem cell survival and continuous oocyte production. We find that progeroid BAF causes defects in germline stem cell mitosis that delay anaphase progression and compromise chromosome segregation. We link these defects to decreased recruitment of centromeric proteins of the kinetochore, indicating dysfunction of cenBAF, a localized pool of dephosphorylated BAF produced by Protein Phosphatase PP4. We show that DNA damage increases in progenitor germ cells, which causes germ cell death due to activation of the DNA damage transducer kinase Chk2. Mitotic defects appear widespread, as aberrant chromosome segregation and increased apoptosis occur in another tissue. Together, these data highlight the importance of BAF in establishing centromeric structures critical for mitosis. Further, these studies link defects in cenBAF function to activation of a checkpoint that depletes progenitor reserves critical for tissue homeostasis, aligning with phenotypes of NGPS patients.
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Kitzman SC, Duan T, Pufall MA, Geyer PK. Checkpoint activation drives global gene expression changes in Drosophila nuclear lamina mutants. G3 (Bethesda) 2022; 12:6459172. [PMID: 34893833 PMCID: PMC9210273 DOI: 10.1093/g3journal/jkab408] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/30/2021] [Accepted: 11/22/2021] [Indexed: 11/25/2022]
Abstract
The nuclear lamina (NL) lines the inner nuclear membrane. This extensive protein network organizes chromatin and contributes to the regulation of transcription, DNA replication, and repair. Lap2-emerin-MAN1 domain (LEM-D) proteins are key members of the NL, representing proteins that connect the NL to the genome through shared interactions with the chromatin-binding protein Barrier-to-Autointegration Factor (BAF). Functions of the LEM-D protein emerin and BAF are essential during Drosophila melanogaster oogenesis. Indeed, loss of either emerin or BAF blocks germ cell development and causes loss of germline stem cells, defects linked to the deformation of NL structure, and non-canonical activation of Checkpoint kinase 2 (Chk2). Here, we investigate the contributions of emerin and BAF to gene expression in the ovary. Profiling RNAs from emerin and baf mutant ovaries revealed that nearly all baf misregulated genes were shared with emerin mutants, defining a set of NL-regulated genes. Strikingly, loss of Chk2 restored the expression of most NL-regulated genes, identifying a large class of Chk2-dependent genes (CDGs). Nonetheless, some genes remained misexpressed upon Chk2 loss, identifying a smaller class of emerin-dependent genes (EDGs). Properties of EDGs suggest a shared role for emerin and BAF in the repression of developmental genes. Properties of CDGs demonstrate that Chk2 activation drives global misexpression of genes in the emerin and baf mutant backgrounds. Notably, CDGs were found upregulated in lamin-B mutant backgrounds. These observations predict that Chk2 activation might have a general role in gene expression changes found in NL-associated diseases, such as laminopathies.
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Affiliation(s)
| | - Tingting Duan
- Department of Biochemistry, University of Iowa, Iowa City, IA 52242, USA
| | - Miles A Pufall
- Department of Biochemistry, University of Iowa, Iowa City, IA 52242, USA
| | - Pamela K Geyer
- Department of Biochemistry, University of Iowa, Iowa City, IA 52242, USA
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Zhang G, Yu T, Parhad SS, Ho S, Weng Z, Theurkauf WE. piRNA-independent transposon silencing by the Drosophila THO complex. Dev Cell 2021; 56:2623-2635.e5. [PMID: 34547226 DOI: 10.1016/j.devcel.2021.08.021] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2021] [Revised: 06/18/2021] [Accepted: 08/27/2021] [Indexed: 12/19/2022]
Abstract
piRNAs guide Piwi/Panoramix-dependent H3K9me3 chromatin modification and transposon silencing during Drosophila germline development. The THO RNA export complex is composed of Hpr1, Tho2, and Thoc5-7. Null thoc7 mutations, which displace Thoc5 and Thoc6 from a Tho2-Hpr1 subcomplex, reduce expression of a subset of germline piRNAs and increase transposon expression, suggesting that THO silences transposons by promoting piRNA biogenesis. Here, we show that the thoc7-null mutant combination increases transposon transcription but does not reduce anti-sense piRNAs targeting half of the transcriptionally activated transposon families. These mutations also fail to reduce piRNA-guided H3K9me3 chromatin modification or block Panoramix-dependent silencing of a reporter transgene, and unspliced transposon transcripts co-precipitate with THO through a Piwi- and Panoramix-independent mechanism. Mutations in piwi also dominantly enhance germline defects associated with thoc7-null alleles. THO thus functions in a piRNA-independent transposon-silencing pathway, which acts cooperatively with Piwi to support germline development.
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Affiliation(s)
- Gen Zhang
- Program in Molecular Medicine, University of Massachusetts Medical School, 373 Plantation Street, Worcester, MA 01605, USA
| | - Tianxiong Yu
- Program in Bioinformatics and Integrative Biology, University of Massachusetts Medical School, 373 Plantation Street, Worcester, MA 01605, USA; Department of Bioinformatics, School of Life Sciences and Technology, Tongji University, Shanghai, People's Republic of China
| | - Swapnil S Parhad
- Program in Molecular Medicine, University of Massachusetts Medical School, 373 Plantation Street, Worcester, MA 01605, USA
| | - Samantha Ho
- Program in Molecular Medicine, University of Massachusetts Medical School, 373 Plantation Street, Worcester, MA 01605, USA
| | - Zhiping Weng
- Program in Bioinformatics and Integrative Biology, University of Massachusetts Medical School, 373 Plantation Street, Worcester, MA 01605, USA.
| | - William E Theurkauf
- Program in Molecular Medicine, University of Massachusetts Medical School, 373 Plantation Street, Worcester, MA 01605, USA.
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Duan T, Cupp R, Geyer PK. Drosophila female germline stem cells undergo mitosis without nuclear breakdown. Curr Biol 2021; 31:1450-1462.e3. [PMID: 33548191 DOI: 10.1016/j.cub.2021.01.033] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2020] [Revised: 11/18/2020] [Accepted: 01/11/2021] [Indexed: 02/02/2023]
Abstract
Stem cell homeostasis requires nuclear lamina (NL) integrity. In Drosophila germ cells, compromised NL integrity activates the ataxia telangiectasia and Rad3-related (ATR) and checkpoint kinase 2 (Chk2) checkpoint kinases, blocking germ cell differentiation and causing germline stem cell (GSC) loss. Checkpoint activation occurs upon loss of either the NL protein emerin or its partner barrier-to-autointegration factor, two proteins required for nuclear reassembly at the end of mitosis. Here, we examined how mitosis contributes to NL structural defects linked to checkpoint activation. These analyses led to the unexpected discovery that wild-type female GSCs utilize a non-canonical mode of mitosis, one that retains a permeable but intact nuclear envelope and NL. We show that the interphase NL is remodeled during mitosis for insertion of centrosomes that nucleate the mitotic spindle within the confines of the nucleus. We show that depletion or loss of NL components causes mitotic defects, including compromised chromosome segregation associated with altered centrosome positioning and structure. Further, in emerin mutant GSCs, centrosomes remain embedded in the interphase NL. Notably, these embedded centrosomes carry large amounts of pericentriolar material and nucleate astral microtubules, revealing a role for emerin in the regulation of centrosome structure. Epistasis studies demonstrate that defects in centrosome structure are upstream of checkpoint activation, suggesting that these centrosome defects might trigger checkpoint activation and GSC loss. Connections between NL proteins and centrosome function have implications for mechanisms associated with NL dysfunction in other stem cell populations, including NL-associated diseases, such as laminopathies.
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Duan T, Green N, Tootle TL, Geyer PK. Nuclear architecture as an intrinsic regulator of Drosophila female germline stem cell maintenance. Curr Opin Insect Sci 2020; 37:30-38. [PMID: 32087561 PMCID: PMC7089816 DOI: 10.1016/j.cois.2019.11.007] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/09/2019] [Revised: 11/08/2019] [Accepted: 11/13/2019] [Indexed: 05/08/2023]
Abstract
Homeostasis of Drosophila germline stem cells (GSC) depends upon the integration of intrinsic and extrinsic signals. This review highlights emerging data that support nuclear architecture as an intrinsic regulator of GSC maintenance and germ cell differentiation. Here, we focus on the nuclear lamina (NL) and the nucleolus, two compartments that undergo alterations in composition upon germ cell differentiation. Loss of NL or nucleolar components leads to GSC loss, resulting from activation of GSC quality control checkpoint pathways. We suggest that the NL and nucleolus integrate signals needed for the switch between GSC maintenance and germ cell differentiation, and propose regulation of nuclear actin pools as one mechanism that connects these compartments.
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Affiliation(s)
- Tingting Duan
- Departments of Biochemistry, University of Iowa, College of Medicine, Iowa City, IA 52242, USA
| | - Nicole Green
- Anatomy and Cell Biology, University of Iowa, College of Medicine, Iowa City, IA 52242, USA
| | - Tina L Tootle
- Anatomy and Cell Biology, University of Iowa, College of Medicine, Iowa City, IA 52242, USA
| | - Pamela K Geyer
- Departments of Biochemistry, University of Iowa, College of Medicine, Iowa City, IA 52242, USA.
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Benner L, Castro EA, Whitworth C, Venken KJT, Yang H, Fang J, Oliver B, Cook KR, Lerit DA. Drosophila Heterochromatin Stabilization Requires the Zinc-Finger Protein Small Ovary. Genetics 2019; 213:877-895. [PMID: 31558581 PMCID: PMC6827387 DOI: 10.1534/genetics.119.302590] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2019] [Accepted: 09/21/2019] [Indexed: 02/04/2023] Open
Abstract
Heterochromatin-mediated repression is essential for controlling the expression of transposons and for coordinated cell type-specific gene regulation. The small ovary (sov) locus was identified in a screen for female-sterile mutations in Drosophila melanogaster, and mutants show dramatic ovarian morphogenesis defects. We show that the null sov phenotype is lethal and map the locus to the uncharacterized gene CG14438, which encodes a nuclear zinc-finger protein that colocalizes with the essential Heterochromatin Protein 1 (HP1a). We demonstrate Sov functions to repress inappropriate gene expression in the ovary, silence transposons, and suppress position-effect variegation in the eye, suggesting a central role in heterochromatin stabilization.
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Affiliation(s)
- Leif Benner
- Section of Developmental Genomics, Laboratory of Cellular and Developmental Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892
- Department of Biology, Johns Hopkins University, Baltimore, Maryland 21218
| | - Elias A Castro
- Department of Cell Biology, Emory University School of Medicine, Atlanta, Georgia 30322
| | - Cale Whitworth
- Section of Developmental Genomics, Laboratory of Cellular and Developmental Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892
- Department of Biology, Indiana University, Bloomington, Indiana 47405
| | - Koen J T Venken
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology
- McNair Medical Institute at the Robert and Janice McNair Foundation
- Dan L. Duncan Cancer Center, Center for Drug Discovery
- Department of Pharmacology and Chemical Biology, Baylor College of Medicine, Houston, Texas 77030
| | - Haiwang Yang
- Section of Developmental Genomics, Laboratory of Cellular and Developmental Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892
| | - Junnan Fang
- Department of Cell Biology, Emory University School of Medicine, Atlanta, Georgia 30322
| | - Brian Oliver
- Section of Developmental Genomics, Laboratory of Cellular and Developmental Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892
| | - Kevin R Cook
- Department of Biology, Indiana University, Bloomington, Indiana 47405
| | - Dorothy A Lerit
- Department of Cell Biology, Emory University School of Medicine, Atlanta, Georgia 30322
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Kahney EW, Snedeker JC, Chen X. Regulation of Drosophila germline stem cells. Curr Opin Cell Biol 2019; 60:27-35. [PMID: 31014993 DOI: 10.1016/j.ceb.2019.03.008] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2019] [Revised: 03/12/2019] [Accepted: 03/15/2019] [Indexed: 12/16/2022]
Abstract
The asymmetric division of adult stem cells into one self-renewing stem cell and one differentiating cell is critical for maintaining homeostasis in many tissues. One paradigmatic model of this division is the Drosophila male and female germline stem cell, which provides two model systems not only sharing common features but also having distinct characteristics for studying asymmetric stem cell division in vivo. This asymmetric division is controlled by a combination of extrinsic signaling molecules and intrinsic factors that are either asymmetrically segregated or regulated differentially following division. In this review, we will discuss recent advances in understanding the molecular and cellular mechanisms guiding this asymmetric outcome, including extrinsic cues, intrinsic factors governing cell fate specification, and cell cycle control.
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Affiliation(s)
- Elizabeth W Kahney
- Department of Biology, The Johns Hopkins University, 3400 North Charles Street, Baltimore, MD 21218, USA
| | - Jonathan C Snedeker
- Department of Biology, The Johns Hopkins University, 3400 North Charles Street, Baltimore, MD 21218, USA
| | - Xin Chen
- Department of Biology, The Johns Hopkins University, 3400 North Charles Street, Baltimore, MD 21218, USA.
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Abstract
Drosophila Suppressor of Hairy-wing [Su(Hw)] is a multifunctional zinc finger DNA binding protein. Transcriptional regulation by Su(Hw) is essential in the ovary and testis, where Su(Hw) functions primarily as a repressor. Recently, the HP1a and Insulator Partner Protein 1 (HIPP1) was found to extensively co-localize with Su(Hw) and other insulator binding proteins in euchromatic regions of the genome, and with Heterochromatin Protein 1a (HP1a) in heterochromatic regions. As HIPP1 is the homolog of the human co-repressor Chromodomain Y-Like (CDYL), we tested its requirement in establishing transcriptional repression in flies. To this end, we generated multiple Hipp1 null alleles and a tagged derivative of the endogenous gene (Hipp1GFP), using CRISPR mutagenesis. We show that HIPP1 is a widely expressed nuclear protein that is dispensable for viability, as well as female and male fertility. We find that HIPP1 and HP1a display minimum co-localization in interphase cells, and HP1a-dependent transcriptional repression of several reporter genes is HIPP1-independent, indicating that HIPP1 is not essential for HP1a-dependent heterochromatin formation. Despite Su(Hw) having a major role in promoting HIPP1 occupancy in euchromatin, we show that HIPP1 is dispensable for the transcriptional and insulator functions of Su(Hw), indicating that HIPP1 is not a critical Su(Hw) cofactor. Further studies are needed to clarify the role of HIPP1 in Drosophila development.
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Barton LJ, Duan T, Ke W, Luttinger A, Lovander KE, Soshnev AA, Geyer PK. Nuclear lamina dysfunction triggers a germline stem cell checkpoint. Nat Commun 2018; 9:3960. [PMID: 30262885 PMCID: PMC6160405 DOI: 10.1038/s41467-018-06277-z] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2017] [Accepted: 08/13/2018] [Indexed: 12/13/2022] Open
Abstract
LEM domain (LEM-D) proteins are conserved components of the nuclear lamina (NL) that contribute to stem cell maintenance through poorly understood mechanisms. The Drosophila emerin homolog Otefin (Ote) is required for maintenance of germline stem cells (GSCs) and gametogenesis. Here, we show that ote mutants carry germ cell-specific changes in nuclear architecture that are linked to GSC loss. Strikingly, we found that both GSC death and gametogenesis are rescued by inactivation of the DNA damage response (DDR) kinases, ATR and Chk2. Whereas the germline checkpoint draws from components of the DDR pathway, genetic and cytological features of the GSC checkpoint differ from the canonical pathway. Instead, structural deformation of the NL correlates with checkpoint activation. Despite remarkably normal oogenesis, rescued oocytes do not support embryogenesis. Taken together, these data suggest that NL dysfunction caused by Otefin loss triggers a GSC-specific checkpoint that contributes to maintenance of gamete quality. Otefin is a nuclear lamina protein required for survival of Drosophila germ stem cells. Here the authors show that nuclear lamina dysfunction resulting from loss of Otefin activates a DNA damage-independent germ stem cell-specific checkpoint, mediated by the ATR and Chk2 kinases, which ensures that healthy gametes are passed on to the next generation.
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Affiliation(s)
- Lacy J Barton
- Department of Biochemistry, University of Iowa, Iowa City, IA, 52242, USA.,Department of Cell Biology, Skirball Institute, NYU School of Medicine, 540 First Avenue, New York, NY, 10016, USA
| | - Tingting Duan
- Department of Biochemistry, University of Iowa, Iowa City, IA, 52242, USA
| | - Wenfan Ke
- Department of Biochemistry, University of Iowa, Iowa City, IA, 52242, USA.,Department of Biology, University of Virginia, 485 McCormick Rd, Charlottesville, VA, 22904, USA
| | - Amy Luttinger
- Department of Biochemistry, University of Iowa, Iowa City, IA, 52242, USA
| | - Kaylee E Lovander
- Department of Biochemistry, University of Iowa, Iowa City, IA, 52242, USA
| | - Alexey A Soshnev
- Department of Biochemistry, University of Iowa, Iowa City, IA, 52242, USA.,Laboratory of Chromatin Biology and Epigenetics, The Rockefeller University, 1230 York Avenue, New York, NY, 10065, USA
| | - Pamela K Geyer
- Department of Biochemistry, University of Iowa, Iowa City, IA, 52242, USA.
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Zheng X, Hu J, Yue S, Kristiani L, Kim M, Sauria M, Taylor J, Kim Y, Zheng Y. Lamins Organize the Global Three-Dimensional Genome from the Nuclear Periphery. Mol Cell 2018; 71:802-815.e7. [PMID: 30201095 DOI: 10.1016/j.molcel.2018.05.017] [Citation(s) in RCA: 115] [Impact Index Per Article: 19.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2017] [Revised: 04/01/2018] [Accepted: 05/15/2018] [Indexed: 11/29/2022]
Abstract
Lamins are structural components of the nuclear lamina (NL) that regulate genome organization and gene expression, but the mechanism remains unclear. Using Hi-C, we show that lamins maintain proper interactions among the topologically associated chromatin domains (TADs) but not their overall architecture. Combining Hi-C with fluorescence in situ hybridization (FISH) and analyses of lamina-associated domains (LADs), we reveal that lamin loss causes expansion or detachment of specific LADs in mouse ESCs. The detached LADs disrupt 3D interactions of both LADs and interior chromatin. 4C and epigenome analyses further demonstrate that lamins maintain the active and repressive chromatin domains among different TADs. By combining these studies with transcriptome analyses, we found a significant correlation between transcription changes and the interaction changes of active and inactive chromatin domains These findings provide a foundation to further study how the nuclear periphery impacts genome organization and transcription in development and NL-associated diseases.
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Affiliation(s)
- Xiaobin Zheng
- Department of Embryology, Carnegie Institution for Science, Baltimore, MD 21218, USA.
| | - Jiabiao Hu
- Department of Embryology, Carnegie Institution for Science, Baltimore, MD 21218, USA
| | - Sibiao Yue
- Department of Embryology, Carnegie Institution for Science, Baltimore, MD 21218, USA
| | - Lidya Kristiani
- Soonchunhyang Institute of Medi-Bio Science (SIMS), Soonchunhyang University, 25 Bongjeong-ro, Cheonan-si, Chungcheongnam-do 31151, Korea
| | - Miri Kim
- Soonchunhyang Institute of Medi-Bio Science (SIMS), Soonchunhyang University, 25 Bongjeong-ro, Cheonan-si, Chungcheongnam-do 31151, Korea
| | - Michael Sauria
- Department of Biology and Department of Computer Science, The Johns Hopkins University, Baltimore, MD 21218, USA
| | - James Taylor
- Department of Biology and Department of Computer Science, The Johns Hopkins University, Baltimore, MD 21218, USA
| | - Youngjo Kim
- Soonchunhyang Institute of Medi-Bio Science (SIMS), Soonchunhyang University, 25 Bongjeong-ro, Cheonan-si, Chungcheongnam-do 31151, Korea.
| | - Yixian Zheng
- Department of Embryology, Carnegie Institution for Science, Baltimore, MD 21218, USA.
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Bhide S, Trujillo AS, O'Connor MT, Young GH, Cryderman DE, Chandran S, Nikravesh M, Wallrath LL, Melkani GC. Increasing autophagy and blocking Nrf2 suppress laminopathy-induced age-dependent cardiac dysfunction and shortened lifespan. Aging Cell 2018; 17:e12747. [PMID: 29575479 PMCID: PMC5946079 DOI: 10.1111/acel.12747] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/10/2018] [Indexed: 12/16/2022] Open
Abstract
Mutations in the human LMNA gene cause a collection of diseases known as laminopathies. These include myocardial diseases that exhibit age-dependent penetrance of dysrhythmias and heart failure. The LMNA gene encodes A-type lamins, intermediate filaments that support nuclear structure and organize the genome. Mechanisms by which mutant lamins cause age-dependent heart defects are not well understood. To address this issue, we modeled human disease-causing mutations in the Drosophila melanogaster Lamin C gene and expressed mutant Lamin C exclusively in the heart. This resulted in progressive cardiac dysfunction, loss of adipose tissue homeostasis, and a shortened adult lifespan. Within cardiac cells, mutant Lamin C aggregated in the cytoplasm, the CncC(Nrf2)/Keap1 redox sensing pathway was activated, mitochondria exhibited abnormal morphology, and the autophagy cargo receptor Ref2(P)/p62 was upregulated. Genetic analyses demonstrated that simultaneous over-expression of the autophagy kinase Atg1 gene and an RNAi against CncC eliminated the cytoplasmic protein aggregates, restored cardiac function, and lengthened lifespan. These data suggest that simultaneously increasing rates of autophagy and blocking the Nrf2/Keap1 pathway are a potential therapeutic strategy for cardiac laminopathies.
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Affiliation(s)
- Shruti Bhide
- Department of Biology, Molecular Biology and Heart Institutes; San Diego State University; San Diego CA USA
| | - Adriana S. Trujillo
- Department of Biology, Molecular Biology and Heart Institutes; San Diego State University; San Diego CA USA
| | - Maureen T. O'Connor
- Department of Biochemistry; Carver College of Medicine; University of Iowa; Iowa City IA USA
| | - Grant H. Young
- Department of Biochemistry; Carver College of Medicine; University of Iowa; Iowa City IA USA
| | - Diane E. Cryderman
- Department of Biochemistry; Carver College of Medicine; University of Iowa; Iowa City IA USA
| | - Sahaana Chandran
- Department of Biology, Molecular Biology and Heart Institutes; San Diego State University; San Diego CA USA
| | - Mastaneh Nikravesh
- Department of Biology, Molecular Biology and Heart Institutes; San Diego State University; San Diego CA USA
| | - Lori L. Wallrath
- Department of Biochemistry; Carver College of Medicine; University of Iowa; Iowa City IA USA
| | - Girish C. Melkani
- Department of Biology, Molecular Biology and Heart Institutes; San Diego State University; San Diego CA USA
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Duan T, Geyer PK. Spermiogenesis and Male Fertility Require the Function of Suppressor of Hairy-Wing in Somatic Cyst Cells of Drosophila. Genetics 2018; 209:757-72. [PMID: 29739818 DOI: 10.1534/genetics.118.301088] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2018] [Accepted: 05/01/2018] [Indexed: 02/07/2023] Open
Abstract
Drosophila Suppressor of Hairy-wing [Su(Hw)] protein is an example of a multivalent transcription factor. Although best known for its role in establishing the chromatin insulator of the gypsy retrotransposon, Su(Hw) functions as an activator and repressor at non-gypsy genomic sites. It remains unclear how the different regulatory activities of Su(Hw) are utilized during development. Motivated from observations of spatially restricted expression of Su(Hw) in the testis, we investigated the role of Su(Hw) in spermatogenesis to advance an understanding of its developmental contributions as an insulator, repressor, and activator protein. We discovered that Su(Hw) is required for sustained male fertility. Although dynamics of Su(Hw) expression coincide with changes in nuclear architecture and activation of coregulated testis-specific gene clusters, we show that loss of Su(Hw) does not disrupt meiotic chromosome pairing or transcription of testis-specific genes, suggesting that Su(Hw) has minor architectural or insulator functions in the testis. Instead, Su(Hw) has a prominent role as a repressor of neuronal genes, consistent with suggestions that Su(Hw) is a functional homolog of mammalian REST, a repressor of neuronal genes in non-neuronal tissues. We show that Su(Hw) regulates transcription in both germline and somatic cells. Surprisingly, the essential spermatogenesis function of Su(Hw) resides in somatic cyst cells, implying context-specific consequences due to loss of this transcription factor. Together, our studies highlight that Su(Hw) has a major developmental function as a transcriptional repressor, with the effect of its loss dependent upon the cell-specific factors.
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