Publications by authors named "Anita H Corbett"

113 Publications

A Budding Yeast Model for Human Disease Mutations in the Cap Subunit of the RNA Exosome.

RNA 2021 Jun 23. Epub 2021 Jun 23.

Emory University;

RNA exosomopathies, a growing family of diseases, are linked to missense mutations in genes encoding structural subunits of the evolutionarily conserved, 10-subunit exoribonuclease complex, the RNA exosome. This complex consists of a 3-subunit cap, a 6-subunit, barrel-shaped, core and a catalytic base subunit. While a number of mutations in RNA exosome genes cause pontocerebellar hypoplasia, mutations in the cap subunit gene cause an apparently distinct clinical presentation that has been defined as a novel syndrome SHRF (Short stature, Hearing loss, Retinitis pigmentosa and distinctive Facies). We generated the first model of the SHRF pathogenic amino acid substitutions using budding yeast by modeling pathogenic missense mutations (p.Gly30Val and p.Gly198Asp) in the orthologous gene The resulting mutant cells show defects in cell growth and RNA exosome function. Consistent with altered RNA exosome function, we detect significant transcriptomic changes in both coding and non-coding RNAs in cells that model p.Gly198Asp, suggesting defects in nuclear surveillance. Biochemical and genetic analyses suggest that the Rrp4 G226D variant subunit shows impaired interactions with key RNA exosome cofactors that modulate the function of the complex. These results provide the first evidence that pathogenic missense mutations present in impair the function of the RNA exosome. This study also sets the stage to compare exosomopathy models to understand how defects in RNA exosome function underlie distinct pathologies.
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http://dx.doi.org/10.1261/rna.078618.120DOI Listing
June 2021

The RNA-binding protein Nab2 regulates the proteome of the developing Drosophila brain.

J Biol Chem 2021 Jun 15;297(1):100877. Epub 2021 Jun 15.

Department of Cell Biology, Emory University School of Medicine, Emory University, Atlanta, Georgia, USA. Electronic address:

The human ZC3H14 gene, which encodes a ubiquitously expressed polyadenosine zinc finger RNA-binding protein, is mutated in an inherited form of autosomal recessive, nonsyndromic intellectual disability. To gain insight into neurological functions of ZC3H14, we previously developed a Drosophila melanogaster model of ZC3H14 loss by deleting the fly ortholog, Nab2. Studies in this invertebrate model revealed that Nab2 controls final patterns of neuron projection within fully developed adult brains, but the role of Nab2 during development of the Drosophila brain is not known. Here, we identify roles for Nab2 in controlling the dynamic growth of axons in the developing brain mushroom bodies, which support olfactory learning and memory, and regulating abundance of a small fraction of the total brain proteome. The group of Nab2-regulated brain proteins, identified by quantitative proteomic analysis, includes the microtubule-binding protein Futsch, the neuronal Ig-family transmembrane protein turtle, the glial:neuron adhesion protein contactin, the Rac GTPase-activating protein tumbleweed, and the planar cell polarity factor Van Gogh, which collectively link Nab2 to the processes of brain morphogenesis, neuroblast proliferation, circadian sleep/wake cycles, and synaptic development. Overall, these data indicate that Nab2 controls the abundance of a subset of brain proteins during the active process of wiring the pupal brain mushroom body and thus provide a window into potentially conserved functions of the Nab2/ZC3H14 RNA-binding proteins in neurodevelopment.
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http://dx.doi.org/10.1016/j.jbc.2021.100877DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8260979PMC
June 2021

An endogenous PI3K interactome promoting astrocyte-mediated neuroprotection identifies a novel association with RNA-binding protein ZC3H14.

J Biol Chem 2021 Jan-Jun;296:100118. Epub 2020 Dec 3.

Department of Vision Science, Krembil Research Institute, University Health Network, Toronto, Ontario, Canada; Department of Ophthalmology and Vision Science, University of Toronto School of Medicine, Toronto, Ontario, Canada. Electronic address:

Astrocytes can support neuronal survival through a range of secreted signals that protect against neurotoxicity, oxidative stress, and apoptotic cascades. Thus, analyzing the effects of the astrocyte secretome may provide valuable insight into these neuroprotective mechanisms. Previously, we characterized a potent neuroprotective activity mediated by retinal astrocyte conditioned media (ACM) on retinal and cortical neurons in metabolic stress models. However, the molecular mechanism underlying this complex activity in neuronal cells has remained unclear. Here, a chemical genetics screen of kinase inhibitors revealed phosphoinositide 3-kinase (PI3K) as a central player transducing ACM-mediated neuroprotection. To identify additional proteins contributing to the protective cascade, endogenous PI3K was immunoprecipitated from neuronal cells exposed to ACM or control media, followed by MS/MS proteomic analyses. These data pointed toward a relatively small number of proteins that coimmunoprecipitated with PI3K, and surprisingly only five were regulated by the ACM signal. These hits included expected PI3K interactors, such as the platelet-derived growth factor receptor A (PDGFRA), as well as novel RNA-binding protein interactors ZC3H14 (zinc finger CCCH-type containing 14) and THOC1 (THO complex protein 1). In particular, ZC3H14 has recently emerged as an important RNA-binding protein with multiple roles in posttranscriptional regulation. In validation studies, we show that PI3K recruitment of ZC3H14 is necessary for PDGF-induced neuroprotection and that this interaction is present in primary retinal ganglion cells. Thus, we identified a novel non-cell autonomous neuroprotective signaling cascade mediated through PI3K that requires recruitment of ZC3H14 and may present a promising strategy to promote astrocyte-secreted prosurvival signals.
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http://dx.doi.org/10.1074/jbc.RA120.015389DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7948738PMC
December 2020

A Genetic Screen Links the Disease-Associated Nab2 RNA-Binding Protein to the Planar Cell Polarity Pathway in .

G3 (Bethesda) 2020 10 5;10(10):3575-3583. Epub 2020 Oct 5.

Emory University School of Medicine, Department of Cell Biology, Atlanta, GA 30322

Mutations in the gene encoding the ubiquitously expressed RNA-binding protein ZC3H14 result in a non-syndromic form of autosomal recessive intellectual disability in humans. Studies in have defined roles for the ZC3H14 ortholog, Nab2 (aka Nab2 or dNab2), in axon guidance and memory due in part to interaction with a second RNA-binding protein, the fly Fragile X homolog Fmr1, and coregulation of shared Nab2-Fmr1 target mRNAs. Despite these advances, neurodevelopmental mechanisms that underlie defective axonogenesis in mutants remain undefined. null phenotypes in the brain mushroom bodies (MBs) resemble defects caused by alleles that disrupt the planar cell polarity (PCP) pathway, which regulates planar orientation of static and motile cells via a non-canonical arm of the Wnt/Wg pathway. A kinked bristle phenotype in surviving mutant adults additionally suggests a defect in F-actin polymerization and bundling, a PCP-regulated processes. To test for Nab2-PCP genetic interactions, a collection of PCP mutant alleles was screened for modification of a rough-eye phenotype produced by Nab2 overexpression in the eye ( ) and, subsequently, for modification of a viability defect among nulls. Multiple PCP alleles dominantly modify eye roughening and a subset rescue low survival and thoracic bristle kinking in zygotic nulls. Collectively, these genetic interactions identify the PCP pathway as a potential target of the Nab2 RNA-binding protein in developing eye and wing tissues and suggest that altered PCP signaling could contribute to neurological defects that result from loss of Nab2 or its vertebrate ortholog ZC3H14.
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http://dx.doi.org/10.1534/g3.120.401637DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7534439PMC
October 2020

Dissecting the roles of Cse1 and Nup2 in classical NLS-cargo release in vivo.

Traffic 2020 10 15;21(10):622-635. Epub 2020 Sep 15.

Department of Biology, Emory University, Atlanta, Georgia, USA.

The importin α/β transport machinery mediates the nuclear import of cargo proteins that bear a classical nuclear localization sequence (cNLS). These cargo proteins are linked to the major nuclear protein import factor, importin-β, by the importin-α adapter, after which cargo/carrier complexes enter the nucleus through nuclear pores. In the nucleus, cargo is released by the action of RanGTP and the nuclear pore protein Nup2, after which the importins are recycled to the cytoplasm for further transport cycles. The nuclear export of importin-α is mediated by Cse1/CAS. Here, we exploit structures of functionally important complexes to identify residues that are critical for these interactions and provide insight into how cycles of protein import and recycling of importin-α occur in vivo using a Saccharomyces cerevisiae model. We examine how these molecular interactions impact protein localization, cargo import, function and complex formation. We show that reversing the charge of key residues in importin-α (Arg44) or Cse1 (Asp220) results in loss of function of the respective proteins and impairs complex formation both in vitro and in vivo. To extend these results, we show that basic residues in the Nup2 N-terminus are required for both Nup2 interaction with importin-α and Nup2 function. These results provide a more comprehensive mechanistic model of how Cse1, RanGTP and Nup2 function in concert to mediate cNLS-cargo release in the nucleus.
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http://dx.doi.org/10.1111/tra.12759DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7891619PMC
October 2020

A Drosophila model of Pontocerebellar Hypoplasia reveals a critical role for the RNA exosome in neurons.

PLoS Genet 2020 07 9;16(7):e1008901. Epub 2020 Jul 9.

Department of Biology, RRC 1021, Emory University, NE, Atlanta, Georgia, United States of America.

The RNA exosome is an evolutionarily-conserved ribonuclease complex critically important for precise processing and/or complete degradation of a variety of cellular RNAs. The recent discovery that mutations in genes encoding structural RNA exosome subunits cause tissue-specific diseases makes defining the role of this complex within specific tissues critically important. Mutations in the RNA exosome component 3 (EXOSC3) gene cause Pontocerebellar Hypoplasia Type 1b (PCH1b), an autosomal recessive neurologic disorder. The majority of disease-linked mutations are missense mutations that alter evolutionarily-conserved regions of EXOSC3. The tissue-specific defects caused by these amino acid changes in EXOSC3 are challenging to understand based on current models of RNA exosome function with only limited analysis of the complex in any multicellular model in vivo. The goal of this study is to provide insight into how mutations in EXOSC3 impact the function of the RNA exosome. To assess the tissue-specific roles and requirements for the Drosophila ortholog of EXOSC3 termed Rrp40, we utilized tissue-specific RNAi drivers. Depletion of Rrp40 in different tissues reveals a general requirement for Rrp40 in the development of many tissues including the brain, but also highlight an age-dependent requirement for Rrp40 in neurons. To assess the functional consequences of the specific amino acid substitutions in EXOSC3 that cause PCH1b, we used CRISPR/Cas9 gene editing technology to generate flies that model this RNA exosome-linked disease. These flies show reduced viability; however, the surviving animals exhibit a spectrum of behavioral and morphological phenotypes. RNA-seq analysis of these Drosophila Rrp40 mutants reveals increases in the steady-state levels of specific mRNAs and ncRNAs, some of which are central to neuronal function. In particular, Arc1 mRNA, which encodes a key regulator of synaptic plasticity, is increased in the Drosophila Rrp40 mutants. Taken together, this study defines a requirement for the RNA exosome in specific tissues/cell types and provides insight into how defects in RNA exosome function caused by specific amino acid substitutions that occur in PCH1b can contribute to neuronal dysfunction.
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http://dx.doi.org/10.1371/journal.pgen.1008901DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7373318PMC
July 2020

Biallelic variants in the RNA exosome gene EXOSC5 are associated with developmental delays, short stature, cerebellar hypoplasia and motor weakness.

Hum Mol Genet 2020 08;29(13):2218-2239

Department of Biology, Emory University, Atlanta, GA 30322, USA.

The RNA exosome is an essential ribonuclease complex required for processing and/or degradation of both coding and non-coding RNAs. We identified five patients with biallelic variants in EXOSC5, which encodes a structural subunit of the RNA exosome. The clinical features of these patients include failure to thrive, short stature, feeding difficulties, developmental delays that affect motor skills, hypotonia and esotropia. Brain MRI revealed cerebellar hypoplasia and ventriculomegaly. While we ascertained five patients, three patients with distinct variants of EXOSC5 were studied in detail. The first patient had a deletion involving exons 5-6 of EXOSC5 and a missense variant, p.Thr114Ile, that were inherited in trans, the second patient was homozygous for p.Leu206His and the third patient had paternal isodisomy for chromosome 19 and was homozygous for p.Met148Thr. The additional two patients ascertained are siblings who had an early frameshift mutation in EXOSC5 and the p.Thr114Ile missense variant that were inherited in trans. We employed three complementary approaches to explore the requirement for EXOSC5 in brain development and assess consequences of pathogenic EXOSC5 variants. Loss of function for exosc5 in zebrafish results in shortened and curved tails/bodies, reduced eye/head size and edema. We modeled pathogenic EXOSC5 variants in both budding yeast and mammalian cells. Some of these variants cause defects in RNA exosome function as well as altered interactions with other RNA exosome subunits. These findings expand the number of genes encoding RNA exosome subunits linked to human disease while also suggesting that disease mechanism varies depending on the specific pathogenic variant.
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http://dx.doi.org/10.1093/hmg/ddaa108DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7399534PMC
August 2020

The RNA Exosome and Human Disease.

Methods Mol Biol 2020 ;2062:3-33

Department of Biology, RRC 1021, Emory University, Atlanta, GA, USA.

The evolutionarily conserved RNA exosome is a multisubunit ribonuclease complex that processes and/or degrades numerous RNAs. Recently, mutations in genes encoding both structural and catalytic subunits of the RNA exosome have been linked to human disease. Mutations in the structural exosome gene EXOSC2 cause a distinct syndrome that includes retinitis pigmentosa, hearing loss, and mild intellectual disability. In contrast, mutations in the structural exosome genes EXOSC3 and EXOSC8 cause pontocerebellar hypoplasia type 1b (PCH1b) and type 1c (PCH1c), respectively, which are related autosomal recessive, neurodegenerative diseases. In addition, mutations in the structural exosome gene EXOSC9 cause a PCH-like disease with cerebellar atrophy and spinal motor neuronopathy. Finally, mutations in the catalytic exosome gene DIS3 have been linked to multiple myeloma, a neoplasm of plasma B cells. How mutations in these RNA exosome genes lead to distinct, tissue-specific diseases is not currently well understood. In this chapter, we examine the role of the RNA exosome complex in human disease and discuss the mechanisms by which mutations in different exosome subunit genes could impair RNA exosome function and give rise to diverse diseases.
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http://dx.doi.org/10.1007/978-1-4939-9822-7_1DOI Listing
December 2020

Depletion of HuR in murine skeletal muscle enhances exercise endurance and prevents cancer-induced muscle atrophy.

Nat Commun 2019 09 13;10(1):4171. Epub 2019 Sep 13.

Department of Biochemistry, McGill University, 3655 Promenade Sir William Osler, Montreal, QC, H3G1Y6, Canada.

The master posttranscriptional regulator HuR promotes muscle fiber formation in cultured muscle cells. However, its impact on muscle physiology and function in vivo is still unclear. Here, we show that muscle-specific HuR knockout (muHuR-KO) mice have high exercise endurance that is associated with enhanced oxygen consumption and carbon dioxide production. muHuR-KO mice exhibit a significant increase in the proportion of oxidative type I fibers in several skeletal muscles. HuR mediates these effects by collaborating with the mRNA decay factor KSRP to destabilize the PGC-1α mRNA. The type I fiber-enriched phenotype of muHuR-KO mice protects against cancer cachexia-induced muscle loss. Therefore, our study uncovers that under normal conditions HuR modulates muscle fiber type specification by promoting the formation of glycolytic type II fibers. We also provide a proof-of-principle that HuR expression can be targeted therapeutically in skeletal muscles to combat cancer-induced muscle wasting.
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http://dx.doi.org/10.1038/s41467-019-12186-6DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6744452PMC
September 2019

A-Tail of Telomerase RNA Maturation.

Mol Cell 2019 05;74(4):635-636

Department of Biology, Emory University, 1510 Clifton Road NE, Atlanta, GA 30322, USA.

In this issue of Molecular Cell, Roake et al. (2019) define a feedforward kinetic pathway consisting of a cycle of oligoadenylation and deadenylation that regulates the production of mature human telomerase RNA.
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http://dx.doi.org/10.1016/j.molcel.2019.04.031DOI Listing
May 2019

Proteomic analysis reveals that wildtype and alanine-expanded nuclear poly(A)-binding protein exhibit differential interactions in skeletal muscle.

J Biol Chem 2019 05 5;294(18):7360-7376. Epub 2019 Mar 5.

From the Department of Biology and

Oculopharyngeal muscular dystrophy (OPMD) is a late-onset, primarily autosomal dominant disease caused by a short GCN expansion in the () gene that results in an alanine expansion at the N terminus of the PABPN1 protein. Expression of alanine-expanded PABPN1 is linked to the formation of nuclear aggregates in tissues from individuals with OPMD. However, as with other nuclear aggregate-associated diseases, controversy exists over whether these aggregates are the direct cause of pathology. An emerging hypothesis is that a loss of PABPN1 function and/or aberrant protein interactions contribute to pathology in OPMD. Here, we present the first global proteomic analysis of the protein interactions of WT and alanine-expanded PABPN1 in skeletal muscle tissue. These data provide both insight into the function of PABPN1 in muscle and evidence that the alanine expansion alters the protein-protein interactions of PABPN1. We extended this analysis to demonstrate altered complex formation with and loss of function of TDP-43 (TAR DNA-binding protein 43), which we show interacts with alanine-expanded but not WT PABPN1. The results from our study support a model where altered protein interactions with alanine-expanded PABPN1 that lead to loss or gain of function could contribute to pathology in OPMD.
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http://dx.doi.org/10.1074/jbc.RA118.007287DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6509510PMC
May 2019

Structure-function relationships in the Nab2 polyadenosine-RNA binding Zn finger protein family.

Protein Sci 2019 03 16;28(3):513-523. Epub 2019 Jan 16.

MRC Laboratory of Molecular Biology, Cambridge Biomedical Campus, Cambridge CB2 0QH, United Kingdom.

The poly(A) RNA binding Zn finger ribonucleoprotein Nab2 functions to control the length of 3' poly(A) tails in Saccharomyces cerevisiae as well as contributing to the integration of the nuclear export of mature mRNA with preceding steps in the nuclear phase of the gene expression pathway. Nab2 is constructed from an N-terminal PWI-fold domain, followed by QQQP and RGG motifs and then seven CCCH Zn fingers. The nuclear pore-associated proteins Gfd1 and Mlp1 bind to opposite sides of the Nab2 N-terminal domain and function in the nuclear export of mRNA, whereas the Zn fingers, especially fingers 5-7, bind to A-rich regions of mature transcripts and function to regulate poly(A) tail length as well as mRNA compaction prior to nuclear export. Nab2 Zn fingers 5-7 have a defined spatial arrangement, with fingers 5 and 7 arranged on one side of the cluster and finger 6 on the other side. This spatial arrangement facilitates the dimerization of Nab2 when bound to adenine-rich RNAs and regulates both the termination of 3' polyadenylation and transcript compaction. Nab2 also functions to coordinate steps in the nuclear phase of the gene expression pathway, such as splicing and polyadenylation, with the generation of mature mRNA and its nuclear export. Nab2 orthologues in higher Eukaryotes have similar domain structures and play roles associated with the regulation of splicing and polyadenylation. Importantly, mutations in the gene encoding the human Nab2 orthologue ZC3H14 and cause intellectual disability.
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http://dx.doi.org/10.1002/pro.3565DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6371209PMC
March 2019

Post-transcriptional regulation of Pabpn1 by the RNA binding protein HuR.

Nucleic Acids Res 2018 09;46(15):7643-7661

Department of Biology, Emory University, Atlanta, GA 30322, USA.

RNA processing is critical for proper spatial and temporal control of gene expression. The ubiquitous nuclear polyadenosine RNA binding protein, PABPN1, post-transcriptionally regulates multiple steps of gene expression. Mutations in the PABPN1 gene expanding an N-terminal alanine tract in the PABPN1 protein from 10 alanines to 11-18 alanines cause the muscle-specific disease oculopharyngeal muscular dystrophy (OPMD), which affects eyelid, pharynx, and proximal limb muscles. Previous work revealed that the Pabpn1 transcript is unstable, contributing to low steady-state Pabpn1 mRNA and protein levels in vivo, specifically in skeletal muscle, with even lower levels in muscles affected in OPMD. Thus, low levels of PABPN1 protein could predispose specific tissues to pathology in OPMD. However, no studies have defined the mechanisms that regulate Pabpn1 expression. Here, we define multiple cis-regulatory elements and a trans-acting factor, HuR, which regulate Pabpn1 expression specifically in mature muscle in vitro and in vivo. We exploit multiple models including C2C12 myotubes, primary muscle cells, and mice to determine that HuR decreases Pabpn1 expression. Overall, we have uncovered a mechanism in mature muscle that negatively regulates Pabpn1 expression in vitro and in vivo, which could provide insight to future studies investigating therapeutic strategies for OPMD treatment.
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http://dx.doi.org/10.1093/nar/gky535DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6125628PMC
September 2018

The polyadenosine RNA-binding protein ZC3H14 interacts with the THO complex and coordinately regulates the processing of neuronal transcripts.

Nucleic Acids Res 2018 07;46(13):6561-6575

Department of Biology, Emory University, Atlanta, GA 30322, USA.

The polyadenosine RNA-binding protein ZC3H14 is important in RNA processing. Although ZC3H14 is ubiquitously expressed, mutation of the ZC3H14 gene causes a non-syndromic form of intellectual disability. Here, we examine the function of ZC3H14 in the brain by identifying ZC3H14-interacting proteins using unbiased mass spectrometry. Through this analysis, we identified physical interactions between ZC3H14 and multiple RNA processing factors. Notably, proteins that comprise the THO complex were amongst the most enriched proteins. We demonstrate that ZC3H14 physically interacts with THO components and that these proteins are required for proper RNA processing, as loss of ZC3H14 or THO components leads to extended bulk poly(A) tail length. Furthermore, we identified the transcripts Atp5g1 and Psd95 as shared RNA targets of ZC3H14 and the THO complex. Our data suggest that ZC3H14 and the THO complex are important for proper processing of Atp5g1 and Psd95 RNA, as depletion of ZC3H14 or THO components leads to decreased steady-state levels of each mature transcript accompanied by accumulation of Atp5g1 and Psd95 pre-mRNA in the cytoplasm. Taken together, this work provides the first unbiased identification of nuclear ZC3H14-interacting proteins from the brain and links the functions of ZC3H14 and the THO complex in the processing of RNA.
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http://dx.doi.org/10.1093/nar/gky446DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6061872PMC
July 2018

Biochemical Isolation of Myonuclei from Mouse Skeletal Muscle Tissue.

Bio Protoc 2017 Dec;7(24)

Pharmacology Department, Emory University, Atlanta, USA.

Skeletal muscle provides the contractile force necessary for movement, swallowing, and breathing and, consequently, is necessary for survival. Skeletal muscle cells are unique in that they are extremely large cells containing thousands of nuclei. These nuclei must all work in concert to maintain skeletal muscle function and thereby maintain life. The nucleus is a major site of signaling integration and gene expression regulation. However, examining nuclear processes in skeletal muscle can be difficult because myonuclei are challenging to isolate. We optimized a protocol to purify myonuclei from whole muscle tissue using ultracentrifugation over a discontinuous sucrose gradient to separate the nuclear fraction. We used these purified nuclei for downstream applications including flow cytometry and mass spectrometry. We used this method to compare the myonuclear proteome of young and old mouse hindlimb muscles (Cutler ., 2017). This protocol may be applied to isolating myonuclei for a variety of downstream analyses such as flow cytometry, microscopy, Western blot, and proteomics.
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http://dx.doi.org/10.21769/BioProtoc.2654DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5868967PMC
December 2017

Overexpression of the base excision repair NTHL1 glycosylase causes genomic instability and early cellular hallmarks of cancer.

Nucleic Acids Res 2018 05;46(9):4515-4532

Department of Biochemistry, Emory University School of Medicine, Atlanta, GA 30322, USA.

Base excision repair (BER), which is initiated by DNA N-glycosylase proteins, is the frontline for repairing potentially mutagenic DNA base damage. The NTHL1 glycosylase, which excises DNA base damage caused by reactive oxygen species, is thought to be a tumor suppressor. However, in addition to NTHL1 loss-of-function mutations, our analysis of cancer genomic datasets reveals that NTHL1 frequently undergoes amplification or upregulation in some cancers. Whether NTHL1 overexpression could contribute to cancer phenotypes has not yet been explored. To address the functional consequences of NTHL1 overexpression, we employed transient overexpression. Both NTHL1 and a catalytically-dead NTHL1 (CATmut) induce DNA damage and genomic instability in non-transformed human bronchial epithelial cells (HBEC) when overexpressed. Strikingly, overexpression of either NTHL1 or CATmut causes replication stress signaling and a decrease in homologous recombination (HR). HBEC cells that overexpress NTHL1 or CATmut acquire the ability to grow in soft agar and exhibit loss of contact inhibition, suggesting that a mechanism independent of NTHL1 catalytic activity contributes to acquisition of cancer-related cellular phenotypes. We provide evidence that NTHL1 interacts with the multifunctional DNA repair protein XPG suggesting that interference with HR is a possible mechanism that contributes to acquisition of early cellular hallmarks of cancer.
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http://dx.doi.org/10.1093/nar/gky162DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5961185PMC
May 2018

Post-transcriptional regulation of gene expression and human disease.

Authors:
Anita H Corbett

Curr Opin Cell Biol 2018 06 6;52:96-104. Epub 2018 Mar 6.

Department of Biology, RRC 1021, Emory University, 1510 Clifton Road, NE, Atlanta 30322, GA, United States. Electronic address:

A large number of mutations in genes that encode RNA binding proteins cause human disease. Many of these RNA binding proteins mediate key steps in post-transcriptional regulation of gene expression from mRNA processing to eventual decay in the cytoplasm. Surprisingly, these RNA binding proteins, which are ubiquitously expressed and play fundamental roles in gene expression, are often altered in tissue-specific disease. Mutations linked to disease impact nearly every post-transcriptional processing step and cause diverse disease phenotypes in a variety of specific tissues. This review summarizes steps in post-transcriptional regulation of gene expression that have been linked to disease providing specific examples of some of the many genes affected. Finally, recent advances that hold promise for treatment of some of these diseases are presented.
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http://dx.doi.org/10.1016/j.ceb.2018.02.011DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5988930PMC
June 2018

Non-equivalence of nuclear import among nuclei in multinucleated skeletal muscle cells.

J Cell Sci 2018 02 5;131(3). Epub 2018 Feb 5.

Department of Pharmacology, Emory University, Atlanta, GA 30322, USA

Skeletal muscle is primarily composed of large myofibers containing thousands of post-mitotic nuclei distributed throughout a common cytoplasm. Protein production and localization in specialized myofiber regions is crucial for muscle function. Myonuclei differ in transcriptional activity and protein accumulation, but how these differences among nuclei sharing a cytoplasm are achieved is unknown. Regulated nuclear import of proteins is one potential mechanism for regulating transcription spatially and temporally in individual myonuclei. The best-characterized nuclear localization signal (NLS) in proteins is the classical NLS (cNLS), but many other NLS motifs exist. We examined cNLS and non-cNLS reporter protein import using multinucleated muscle cells generated , revealing that cNLS and non-cNLS nuclear import differs among nuclei in the same cell. Investigation of cNLS nuclear import rates in isolated myofibers confirmed differences in nuclear import rates among myonuclei. Analyzing nuclear import throughout myogenesis revealed that cNLS and non-cNLS import varies during differentiation. Taken together, our results suggest that both spatial and temporal regulation of nuclear import pathways are important in muscle cell differentiation and protein regionalization in myofibers.
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http://dx.doi.org/10.1242/jcs.207670DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5826044PMC
February 2018

The RNA exosome and RNA exosome-linked disease.

RNA 2018 02 1;24(2):127-142. Epub 2017 Nov 1.

Department of Biology, Emory University, NE, Atlanta, Georgia 30322, USA.

The RNA exosome is an evolutionarily conserved, ribonuclease complex that is critical for both processing and degradation of a variety of RNAs. Cofactors that associate with the RNA exosome likely dictate substrate specificity for this complex. Recently, mutations in genes encoding both structural subunits of the RNA exosome and its cofactors have been linked to human disease. Mutations in the RNA exosome genes and cause pontocerebellar hypoplasia type 1b (PCH1b) and type 1c (PCH1c), respectively, which are similar autosomal-recessive, neurodegenerative diseases. Mutations in the RNA exosome gene cause a distinct syndrome with various tissue-specific phenotypes including retinitis pigmentosa and mild intellectual disability. Mutations in genes that encode RNA exosome cofactors also cause tissue-specific diseases with complex phenotypes. How mutations in these genes give rise to distinct, tissue-specific diseases is not clear. In this review, we discuss the role of the RNA exosome complex and its cofactors in human disease, consider the amino acid changes that have been implicated in disease, and speculate on the mechanisms by which exosome gene mutations could underlie dysfunction and disease.
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http://dx.doi.org/10.1261/rna.064626.117DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5769741PMC
February 2018

Nuclear poly(A) binding protein 1 (PABPN1) and Matrin3 interact in muscle cells and regulate RNA processing.

Nucleic Acids Res 2017 Oct;45(18):10706-10725

Department of Biology, Emory University, Atlanta, GA 30322, USA.

The polyadenylate binding protein 1 (PABPN1) is a ubiquitously expressed RNA binding protein vital for multiple steps in RNA metabolism. Although PABPN1 plays a critical role in the regulation of RNA processing, mutation of the gene encoding this ubiquitously expressed RNA binding protein causes a specific form of muscular dystrophy termed oculopharyngeal muscular dystrophy (OPMD). Despite the tissue-specific pathology that occurs in this disease, only recently have studies of PABPN1 begun to explore the role of this protein in skeletal muscle. We have used co-immunoprecipitation and mass spectrometry to identify proteins that interact with PABPN1 in mouse skeletal muscles. Among the interacting proteins we identified Matrin 3 (MATR3) as a novel protein interactor of PABPN1. The MATR3 gene is mutated in a form of distal myopathy and amyotrophic lateral sclerosis (ALS). We demonstrate, that like PABPN1, MATR3 is critical for myogenesis. Furthermore, MATR3 controls critical aspects of RNA processing including alternative polyadenylation and intron retention. We provide evidence that MATR3 also binds and regulates the levels of long non-coding RNA (lncRNA) Neat1 and together with PABPN1 is required for normal paraspeckle function. We demonstrate that PABPN1 and MATR3 are required for paraspeckles, as well as for adenosine to inosine (A to I) RNA editing of Ctn RNA in muscle cells. We provide a functional link between PABPN1 and MATR3 through regulation of a common lncRNA target with downstream impact on paraspeckle morphology and function. We extend our analysis to a mouse model of OPMD and demonstrate altered paraspeckle morphology in the presence of endogenous levels of alanine-expanded PABPN1. In this study, we report protein-binding partners of PABPN1, which could provide insight into novel functions of PABPN1 in skeletal muscle and identify proteins that could be sequestered with alanine-expanded PABPN1 in the nuclear aggregates found in OPMD.
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http://dx.doi.org/10.1093/nar/gkx786DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5737383PMC
October 2017

The Conserved, Disease-Associated RNA Binding Protein dNab2 Interacts with the Fragile X Protein Ortholog in Drosophila Neurons.

Cell Rep 2017 08;20(6):1372-1384

Department of Cell Biology, Emory University and Emory University School of Medicine, Atlanta, GA 30322, USA. Electronic address:

The Drosophila dNab2 protein is an ortholog of human ZC3H14, a poly(A) RNA binding protein required for intellectual function. dNab2 supports memory and axon projection, but its molecular role in neurons is undefined. Here, we present a network of interactions that links dNab2 to cytoplasmic control of neuronal mRNAs in conjunction with the fragile X protein ortholog dFMRP. dNab2 and dfmr1 interact genetically in control of neurodevelopment and olfactory memory, and their encoded proteins co-localize in puncta within neuronal processes. dNab2 regulates CaMKII, but not futsch, implying a selective role in control of dFMRP-bound transcripts. Reciprocally, dFMRP and vertebrate FMRP restrict mRNA poly(A) tail length, similar to dNab2/ZC3H14. Parallel studies of murine hippocampal neurons indicate that ZC3H14 is also a cytoplasmic regulator of neuronal mRNAs. Altogether, these findings suggest that dNab2 represses expression of a subset of dFMRP-target mRNAs, which could underlie brain-specific defects in patients lacking ZC3H14.
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http://dx.doi.org/10.1016/j.celrep.2017.07.038DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5577809PMC
August 2017

The RNA-binding protein, ZC3H14, is required for proper poly(A) tail length control, expression of synaptic proteins, and brain function in mice.

Hum Mol Genet 2017 10;26(19):3663-3681

Department of Biology.

A number of mutations in genes that encode ubiquitously expressed RNA-binding proteins cause tissue specific disease. Many of these diseases are neurological in nature revealing critical roles for this class of proteins in the brain. We recently identified mutations in a gene that encodes a ubiquitously expressed polyadenosine RNA-binding protein, ZC3H14 (Zinc finger CysCysCysHis domain-containing protein 14), that cause a nonsyndromic, autosomal recessive form of intellectual disability. This finding reveals the molecular basis for disease and provides evidence that ZC3H14 is essential for proper brain function. To investigate the role of ZC3H14 in the mammalian brain, we generated a mouse in which the first common exon of the ZC3H14 gene, exon 13 is removed (Zc3h14Δex13/Δex13) leading to a truncated ZC3H14 protein. We report here that, as in the patients, Zc3h14 is not essential in mice. Utilizing these Zc3h14Δex13/Δex13mice, we provide the first in vivo functional characterization of ZC3H14 as a regulator of RNA poly(A) tail length. The Zc3h14Δex13/Δex13 mice show enlarged lateral ventricles in the brain as well as impaired working memory. Proteomic analysis comparing the hippocampi of Zc3h14+/+ and Zc3h14Δex13/Δex13 mice reveals dysregulation of several pathways that are important for proper brain function and thus sheds light onto which pathways are most affected by the loss of ZC3H14. Among the proteins increased in the hippocampi of Zc3h14Δex13/Δex13 mice compared to control are key synaptic proteins including CaMK2a. This newly generated mouse serves as a tool to study the function of ZC3H14 in vivo.
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http://dx.doi.org/10.1093/hmg/ddx248DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5886104PMC
October 2017

BERing the burden of damage: Pathway crosstalk and posttranslational modification of base excision repair proteins regulate DNA damage management.

DNA Repair (Amst) 2017 08 9;56:51-64. Epub 2017 Jun 9.

Graduate Program in Cancer Biology, Emory University, Atlanta, GA, 30322, United States; Department of Radiation Oncology, Emory University School of Medicine, Atlanta, GA, 30322, United States; Winship Cancer Institute, Emory University, Atlanta, GA 30322, United States; Department of Biochemistry, Emory University, Atlanta, GA, 30322, United States. Electronic address:

DNA base damage and non-coding apurinic/apyrimidinic (AP) sites are ubiquitous types of damage that must be efficiently repaired to prevent mutations. These damages can occur in both the nuclear and mitochondrial genomes. Base excision repair (BER) is the frontline pathway for identifying and excising damaged DNA bases in both of these cellular compartments. Recent advances demonstrate that BER does not operate as an isolated pathway but rather dynamically interacts with components of other DNA repair pathways to modulate and coordinate BER functions. We define the coordination and interaction between DNA repair pathways as pathway crosstalk. Numerous BER proteins are modified and regulated by post-translational modifications (PTMs), and PTMs could influence pathway crosstalk. Here, we present recent advances on BER/DNA repair pathway crosstalk describing specific examples and also highlight regulation of BER components through PTMs. We have organized and reported functional interactions and documented PTMs for BER proteins into a consolidated summary table. We further propose the concept of DNA repair hubs that coordinate DNA repair pathway crosstalk to identify central protein targets that could play a role in designing future drug targets.
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http://dx.doi.org/10.1016/j.dnarep.2017.06.007DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5576989PMC
August 2017

Novel mouse models of oculopharyngeal muscular dystrophy (OPMD) reveal early onset mitochondrial defects and suggest loss of PABPN1 may contribute to pathology.

Hum Mol Genet 2017 09;26(17):3235-3252

Department of Biology, Emory University, Atlanta, GA, USA.

Oculopharyngeal muscular dystrophy (OPMD) is a late onset disease caused by polyalanine expansion in the poly(A) binding protein nuclear 1 (PABPN1). Several mouse models have been generated to study OPMD; however, most of these models have employed transgenic overexpression of alanine-expanded PABPN1. These models do not recapitulate the OPMD patient genotype and PABPN1 overexpression could confound molecular phenotypes. We have developed a knock-in mouse model of OPMD (Pabpn1+/A17) that contains one alanine-expanded Pabpn1 allele under the control of the native promoter and one wild-type Pabpn1 allele. This mouse is the closest available genocopy of OPMD patients. We show that Pabpn1+/A17 mice have a mild myopathic phenotype in adult and aged animals. We examined early molecular and biochemical phenotypes associated with expressing native levels of A17-PABPN1 and detected shorter poly(A) tails, modest changes in poly(A) signal (PAS) usage, and evidence of mitochondrial damage in these mice. Recent studies have suggested that a loss of PABPN1 function could contribute to muscle pathology in OPMD. To investigate a loss of function model of pathology, we generated a heterozygous Pabpn1 knock-out mouse model (Pabpn1+/Δ). Like the Pabpn1+/A17 mice, Pabpn1+/Δ mice have mild histologic defects, shorter poly(A) tails, and evidence of mitochondrial damage. However, the phenotypes detected in Pabpn1+/Δ mice only partially overlap with those detected in Pabpn1+/A17 mice. These results suggest that loss of PABPN1 function could contribute to but may not completely explain the pathology detected in Pabpn1+/A17 mice.
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http://dx.doi.org/10.1093/hmg/ddx206DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5886286PMC
September 2017

Biochemical isolation of myonuclei employed to define changes to the myonuclear proteome that occur with aging.

Aging Cell 2017 08 23;16(4):738-749. Epub 2017 May 23.

Department of Pharmacology, Emory University, Atlanta, GA, 30322, USA.

Skeletal muscle aging is accompanied by loss of muscle mass and strength. Examining changes in myonuclear proteins with age would provide insight into molecular processes which regulate these profound changes in muscle physiology. However, muscle tissue is highly adapted for contraction and thus comprised largely of contractile proteins making the nuclear proteins difficult to identify from whole muscle samples. By developing a method to purify myonuclei from whole skeletal muscle, we were able to collect myonuclei for analysis by flow cytometry, biochemistry, and mass spectrometry. Nuclear purification dramatically increased the number and intensity of nuclear proteins detected by mass spectrometry compared to whole tissue. We exploited this increased proteomic depth to investigate age-related changes to the myonuclear proteome. Nuclear levels of 54 of 779 identified proteins (7%) changed significantly with age; these proteins were primarily involved in chromatin maintenance and RNA processing. To determine whether the changes we detected were specific to myonuclei or were common to nuclei of excitatory tissues, we compared aging in myonuclei to aging in brain nuclei. Although several of the same processes were affected by aging in both brain and muscle nuclei, the specific proteins involved in these alterations differed between the two tissues. Isolating myonuclei allowed a deeper view into the myonuclear proteome than previously possible facilitating identification of novel age-related changes in skeletal muscle. Our technique will enable future studies into a heretofore underrepresented compartment of skeletal muscle.
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http://dx.doi.org/10.1111/acel.12604DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5506426PMC
August 2017

Links between mRNA splicing, mRNA quality control, and intellectual disability.

RNA Dis 2016 7;3(4). Epub 2016 Nov 7.

Department of Biology, Emory University, 1510 Clifton Rd., NE RRC 1021, Atlanta, GA 30322, U.S.A.

In recent years, the impairment of RNA binding proteins that play key roles in the post-transcriptional regulation of gene expression has been linked to numerous neurological diseases. These RNA binding proteins perform critical mRNA processing steps in the nucleus, including splicing, polyadenylation, and export. In many cases, these RNA binding proteins are ubiquitously expressed raising key questions about why only brain function is impaired. Recently, mutations in the gene, encoding an evolutionarily conserved, polyadenosine RNA binding protein, have been linked to a nonsyndromic form of autosomal recessive intellectual disability. Thus far, research on ZC3H14 and its Nab2 orthologs in budding yeast and reveals that ZC3H14/Nab2 is important for mRNA processing and neuronal patterning. Two recent studies now provide evidence that ZC3H14/Nab2 may function in the quality control of mRNA splicing and export and could help to explain the molecular defects that cause neuronal dysfunction and lead to an inherited form of intellectual disability. These studies on ZC3H14/Nab2 reveal new clues to the puzzle of why loss of the ubiquitously expressed ZC3H14 protein specifically affects neurons.
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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5113822PMC
November 2016

An Antibody to Detect Alanine-Expanded PABPN1: A New Tool to Study Oculopharyngeal Muscular Dystrophy.

J Neuromuscul Dis 2015 Oct;2(4):439-446

Department of Biochemistry, Emory University School of Medicine, Atlanta, GA, USA.

Background: Oculopharyngeal muscular dystrophy (OPMD), a late onset disorder affecting specific skeletal muscles, is caused by a (GCG)n expansion mutation in the gene encoding the mRNA processing protein, polyadenylate binding protein nuclear 1 (PABPN1). The expansion in PABPN1 leads to an increase in a stretch of N-terminal alanine residues in the PABPN1 protein from the normal 10 to 12-18. Given this modest change, detection of mutant protein has not been possible without the use of tagged constructs.

Objective: We sought to generate a polyclonal antibody that recognizes alanine-expanded but not wild type PABPN1 with the goal of making possible analysis of expression and localization of alanine-expanded PABPN1.

Methods: We immunized rabbits with a GST-tagged alanine peptide and tested the resulting serum against alanine-expanded PABPN1 expressed in cell culture as well as in animal models of OPMD.

Results: The resulting α-alanine antibody detected PABPN1 proteins that contained 14 or more alanine residues. Importantly, the α-alanine antibody could be used to detect alanine-expanded PABPN1 in muscles from either a mouse or Drosophila model of OPMD.

Conclusions: This α-alanine antibody provides a new tool that will allow for more in-depth study of how alanine expansion affects aggregation, localization, and steady-state levels of alanine-expanded PABPN1 levels in vivo, providing new insight into the molecular mechanisms underlying OPMD.
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http://dx.doi.org/10.3233/JND-150111DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5207656PMC
October 2015

Gleaning Insights from Fecal Microbiota Transplantation and Probiotic Studies for the Rational Design of Combination Microbial Therapies.

Clin Microbiol Rev 2017 01;30(1):191-231

Department of Pediatric Infectious Diseases, Emory University School of Medicine, Atlanta, Georgia, USA

Beneficial microorganisms hold promise for the treatment of numerous gastrointestinal diseases. The transfer of whole microbiota via fecal transplantation has already been shown to ameliorate the severity of diseases such as Clostridium difficile infection, inflammatory bowel disease, and others. However, the exact mechanisms of fecal microbiota transplant efficacy and the particular strains conferring this benefit are still unclear. Rationally designed combinations of microbial preparations may enable more efficient and effective treatment approaches tailored to particular diseases. Here we use an infectious disease, C. difficile infection, and an inflammatory disorder, the inflammatory bowel disease ulcerative colitis, as examples to facilitate the discussion of how microbial therapy might be rationally designed for specific gastrointestinal diseases. Fecal microbiota transplantation has already shown some efficacy in the treatment of both these disorders; detailed comparisons of studies evaluating commensal and probiotic organisms in the context of these disparate gastrointestinal diseases may shed light on potential protective mechanisms and elucidate how future microbial therapies can be tailored to particular diseases.
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http://dx.doi.org/10.1128/CMR.00049-16DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5217792PMC
January 2017

Identification of SUMO modification sites in the base excision repair protein, Ntg1.

DNA Repair (Amst) 2016 12 31;48:51-62. Epub 2016 Oct 31.

Department of Biochemistry, Emory University School of Medicine, Atlanta, GA 30322, United States; Winship Cancer Institute, Emory University School of Medicine, Atlanta, GA 30322, United States; Department of Radiation Oncology, Emory University School of Medicine, Atlanta, GA 30322, United States; Department of Hematology and Medical Oncology Emory University School of Medicine, Atlanta, GA 30322, United States. Electronic address:

DNA damaging agents are a constant threat to genomes in both the nucleus and the mitochondria. To combat this threat, a suite of DNA repair pathways cooperate to repair numerous types of DNA damage. If left unrepaired, these damages can result in the accumulation of mutations which can lead to deleterious consequences including cancer and neurodegenerative disorders. The base excision repair (BER) pathway is highly conserved from bacteria to humans and is primarily responsible for the removal and subsequent repair of toxic and mutagenic oxidative DNA lesions. Although the biochemical steps that occur in the BER pathway have been well defined, little is known about how the BER machinery is regulated. The budding yeast, Saccharomyces cerevisiae is a powerful model system to biochemically and genetically dissect BER. BER is initiated by DNA N-glycosylases, such as S. cerevisiae Ntg1. Previous work demonstrates that Ntg1 is post-translationally modified by SUMO in response to oxidative DNA damage suggesting that this modification could modulate the function of Ntg1. In this study, we mapped the specific sites of SUMO modification within Ntg1 and identified the enzymes responsible for sumoylating/desumoylating Ntg1. Using a non-sumoylatable version of Ntg1, ntg1ΔSUMO, we performed an initial assessment of the functional impact of Ntg1 SUMO modification in the cellular response to DNA damage. Finally, we demonstrate that, similar to Ntg1, the human homologue of Ntg1, NTHL1, can also be SUMO-modified in response to oxidative stress. Our results suggest that SUMO modification of BER proteins could be a conserved mechanism to coordinate cellular responses to DNA damage.
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http://dx.doi.org/10.1016/j.dnarep.2016.10.011DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5133457PMC
December 2016

Insight into the RNA Exosome Complex Through Modeling Pontocerebellar Hypoplasia Type 1b Disease Mutations in Yeast.

Genetics 2017 01 24;205(1):221-237. Epub 2016 Oct 24.

Department of Microbiology and Molecular Genetics, University of Texas Health Science Center-Houston, Texas 77030

Pontocerebellar hypoplasia type 1b (PCH1b) is an autosomal recessive disorder that causes cerebellar hypoplasia and spinal motor neuron degeneration, leading to mortality in early childhood. PCH1b is caused by mutations in the RNA exosome subunit gene, EXOSC3 The RNA exosome is an evolutionarily conserved complex, consisting of nine different core subunits, and one or two 3'-5' exoribonuclease subunits, that mediates several RNA degradation and processing steps. The goal of this study is to assess the functional consequences of the amino acid substitutions that have been identified in EXOSC3 in PCH1b patients. To analyze these EXOSC3 substitutions, we generated the corresponding amino acid substitutions in the Saccharomyces cerevisiae ortholog of EXOSC3, Rrp40 We find that the rrp40 variants corresponding to EXOSC3-G31A and -D132A do not affect yeast function when expressed as the sole copy of the essential Rrp40 protein. In contrast, the rrp40-W195R variant, corresponding to EXOSC3-W238R in PCH1b patients, impacts cell growth and RNA exosome function when expressed as the sole copy of Rrp40 The rrp40-W195R protein is unstable, and does not associate efficiently with the RNA exosome in cells that also express wild-type Rrp40 Consistent with these findings in yeast, the levels of mouse EXOSC3 variants are reduced compared to wild-type EXOSC3 in a neuronal cell line. These data suggest that cells possess a mechanism for optimal assembly of functional RNA exosome complex that can discriminate between wild-type and variant exosome subunits. Budding yeast can therefore serve as a useful tool to understand the molecular defects in the RNA exosome caused by PCH1b-associated amino acid substitutions in EXOSC3, and potentially extending to disease-associated substitutions in other exosome subunits.
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http://dx.doi.org/10.1534/genetics.116.195917DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5223504PMC
January 2017