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Barman P, Ferdoush J, Kaja A, Chakraborty P, Uprety B, Bhaumik R, Bhaumik R, Bhaumik SR. Ubiquitin-proteasome system regulation of a key gene regulatory factor, Paf1C. Gene 2024; 894:148004. [PMID: 37977317 DOI: 10.1016/j.gene.2023.148004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2023] [Revised: 11/08/2023] [Accepted: 11/14/2023] [Indexed: 11/19/2023]
Abstract
Paf1 (Polymerase-associated factor 1) complex (Paf1C) is evolutionarily conserved from yeast to humans, and facilitates transcription elongation as well as co-transcriptional histone covalent modifications and mRNA 3'-end processing. Thus, Paf1C is a key player in regulation of eukaryotic gene expression. Paf1C consists of Paf1, Cdc73, Ctr9, Leo1 and Rtf1 in both yeast and humans, but it has an additional component, Ski8, in humans. The abundances of these components regulate the assembly of Paf1C and/or its functions, thus implying the mechanisms involved in regulating the abundances of the Paf1C components in altered gene expression and hence cellular pathologies. Towards finding the mechanisms associated with the abundances of the Paf1C components, we analyzed here whether the Paf1C components are regulated via targeted ubiquitylation and 26S proteasomal degradation. We find that the Paf1C components except Paf1 do not undergo the 26S proteasomal degradation in both yeast and humans. Paf1 is found to be regulated by the ubiquitin-proteasome system (UPS) in yeast and humans. Alteration of such regulation changes Paf1's abundance, leading to aberrant gene expression. Intriguingly, while the Rtf1 component of Paf1C does not undergo the 26S proteasomal degradation, it is found to be ubiquitylated, suggesting that Rtf1 ubiquitylation could be engaged in Paf1C assembly and/or functions. Collectively, our results reveal distinct UPS regulation of the Paf1C components, Paf1 and Rtf1, in a proteolysis-dependent and -independent manners, respectively, with functional implications.
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Affiliation(s)
- Priyanka Barman
- Department of Biochemistry and Molecular Biology, Southern Illinois University School of Medicine, Carbondale, IL 62901, USA
| | - Jannatul Ferdoush
- Department of Biochemistry and Molecular Biology, Southern Illinois University School of Medicine, Carbondale, IL 62901, USA
| | - Amala Kaja
- Department of Biochemistry and Molecular Biology, Southern Illinois University School of Medicine, Carbondale, IL 62901, USA
| | - Pritam Chakraborty
- Department of Biochemistry and Molecular Biology, Southern Illinois University School of Medicine, Carbondale, IL 62901, USA
| | - Bhawana Uprety
- Department of Biochemistry and Molecular Biology, Southern Illinois University School of Medicine, Carbondale, IL 62901, USA
| | - Rhea Bhaumik
- Department of Biochemistry and Molecular Biology, Southern Illinois University School of Medicine, Carbondale, IL 62901, USA
| | - Risa Bhaumik
- Department of Biochemistry and Molecular Biology, Southern Illinois University School of Medicine, Carbondale, IL 62901, USA
| | - Sukesh R Bhaumik
- Department of Biochemistry and Molecular Biology, Southern Illinois University School of Medicine, Carbondale, IL 62901, USA.
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2
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Barman P, Kaja A, Chakraborty P, Bhaumik SR. Chromatin and non-chromatin immunoprecipitations to capture protein-protein and protein-nucleic acid interactions in living cells. Methods 2023; 218:158-166. [PMID: 37611837 PMCID: PMC10528071 DOI: 10.1016/j.ymeth.2023.08.013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2023] [Revised: 08/18/2023] [Accepted: 08/19/2023] [Indexed: 08/25/2023] Open
Abstract
Proteins are expressed from genes via sequential biological processes of transcription, mRNA processing, export and translation, and play their roles in maintaining cellular functions via interactions with proteins, DNAs or RNAs. Thus, it is important to study the protein interactions during biological processes in living cells towards understanding their mechanisms-of-action in real time. Methodologies have been developed over the years to study protein interactions in vivo. One state-of-the-art approach is formaldehyde crosslinking-based immuno- or chemi-precipitation to analyze selective as well as genome/proteome-wide interactions in living cells. It is a popular and widely used methodology for cellular analysis of the protein-protein and protein-nucleic acid interactions. Here, we describe this approach to analyze protein-protein/nucleic acid interactions in vivo.
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Affiliation(s)
- Priyanka Barman
- Department of Biochemistry and Molecular Biology, Southern Illinois University School of Medicine, Carbondale, IL 62901, USA
| | - Amala Kaja
- Department of Biochemistry and Molecular Biology, Southern Illinois University School of Medicine, Carbondale, IL 62901, USA
| | - Pritam Chakraborty
- Department of Biochemistry and Molecular Biology, Southern Illinois University School of Medicine, Carbondale, IL 62901, USA
| | - Sukesh R Bhaumik
- Department of Biochemistry and Molecular Biology, Southern Illinois University School of Medicine, Carbondale, IL 62901, USA.
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3
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Kaja A, Barman P, Guha S, Bhaumik SR. Tandem Affinity Purification and Mass-Spectrometric Analysis of FACT and Associated Proteins. Methods Mol Biol 2023; 2701:209-227. [PMID: 37574485 DOI: 10.1007/978-1-0716-3373-1_14] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/15/2023]
Abstract
Isolation of a protein/complex is important for its biochemical and structural characterization with mechanistic insights. TAP (tandem affinity purification) strategy allows rapid isolation of cellular proteins/complexes with a high level of purity. This methodology involves an immuno-affinity-based purification followed by a conformation-based isolation to obtain a highly homogeneous protein/complex. Here, we describe the TAP-mediated isolation of endogenous FACT (facilitates chromatin transcription; a heterodimer), an essential histone chaperone associated with BER (base excision repair). However, it is not clearly understood how FACT regulates BER. Such knowledge would advance our understanding of BER with implications in disease pathogenesis, since BER is an evolutionarily conserved process that is linked to various diseases including ageing, neurodegenerative disorders, and cancers. Using isolated FACT by TAP methodology, one can study the mechanisms of action of FACT in BER. Further, isolated FACT can be used for studies in other DNA transactions such as transcription and replication, as FACT is involved in these processes. Furthermore, TAP-mediated isolation strategy can be combined with mass spectrometry to identify the protein interaction partners of FACT.
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Affiliation(s)
- Amala Kaja
- Department of Biochemistry and Molecular Biology, Southern Illinois University School of Medicine, Carbondale, IL, USA
| | - Priyanka Barman
- Department of Biochemistry and Molecular Biology, Southern Illinois University School of Medicine, Carbondale, IL, USA
| | - Shalini Guha
- Department of Biochemistry and Molecular Biology, Southern Illinois University School of Medicine, Carbondale, IL, USA
| | - Sukesh R Bhaumik
- Department of Biochemistry and Molecular Biology, Southern Illinois University School of Medicine, Carbondale, IL, USA.
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4
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Jeronimo C, Robert F. The histone chaperone FACT: a guardian of chromatin structure integrity. Transcription 2022; 13:16-38. [PMID: 35485711 PMCID: PMC9467567 DOI: 10.1080/21541264.2022.2069995] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
The identification of FACT as a histone chaperone enabling transcription through chromatin in vitro has strongly shaped how its roles are envisioned. However, FACT has been implicated in essentially all aspects of chromatin biology, from transcription to DNA replication, DNA repair, and chromosome segregation. In this review, we focus on recent literature describing the role and mechanisms of FACT during transcription. We highlight the prime importance of FACT in preserving chromatin integrity during transcription and challenge its role as an elongation factor. We also review evidence for FACT's role as a cell-type/gene-specificregulator of gene expression and briefly summarize current efforts at using FACT inhibition as an anti-cancerstrategy.
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Affiliation(s)
- Célia Jeronimo
- Institut de recherches cliniques de Montréal, Montréal, Québec, Canada
| | - François Robert
- Institut de recherches cliniques de Montréal, Montréal, Québec, Canada.,Département de Médecine, Faculté de Médecine, Université de Montréal, Montréal, Québec, Canada.,Faculty of Medicine, Division of Experimental Medicine, McGill University, Montréal, Québec, Canada
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5
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Barman P, Sen R, Kaja A, Ferdoush J, Guha S, Govind CK, Bhaumik SR. Genome-Wide Regulations of the Preinitiation Complex Formation and Elongating RNA Polymerase II by an E3 Ubiquitin Ligase, San1. Mol Cell Biol 2022; 42:e0036821. [PMID: 34661445 PMCID: PMC8773080 DOI: 10.1128/mcb.00368-21] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2021] [Revised: 08/18/2021] [Accepted: 10/12/2021] [Indexed: 11/20/2022] Open
Abstract
San1 ubiquitin ligase is involved in nuclear protein quality control via its interaction with intrinsically disordered proteins for ubiquitylation and proteasomal degradation. Since several transcription/chromatin regulatory factors contain intrinsically disordered domains and can be inhibitory to transcription when in excess, San1 might be involved in transcription regulation. To address this, we analyzed the role of San1 in the genome-wide association of TATA box binding protein (TBP; which nucleates preinitiation complex [PIC] formation for transcription initiation) and RNA polymerase II (Pol II). Our results reveal the roles of San1 in regulating TBP recruitment to the promoters and Pol II association with the coding sequences and, hence, PIC formation and coordination of elongating Pol II, respectively. Consistently, transcription is altered in the absence of San1. Such transcriptional alteration is associated with impaired ubiquitylation and proteasomal degradation of Spt16 and gene association of Paf1 but not the incorporation of centromeric histone, Cse4, into the active genes in the Δsan1 strain. Collectively, our results demonstrate distinct functions of a nuclear protein quality control factor in regulating the genome-wide PIC formation and elongating Pol II (and hence transcription), thus unraveling new gene regulatory mechanisms.
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Affiliation(s)
- Priyanka Barman
- Department of Biochemistry and Molecular Biology, Southern Illinois University School of Medicine, Carbondale, Illinois, USA
| | - Rwik Sen
- Department of Biochemistry and Molecular Biology, Southern Illinois University School of Medicine, Carbondale, Illinois, USA
| | - Amala Kaja
- Department of Biochemistry and Molecular Biology, Southern Illinois University School of Medicine, Carbondale, Illinois, USA
| | - Jannatul Ferdoush
- Department of Biochemistry and Molecular Biology, Southern Illinois University School of Medicine, Carbondale, Illinois, USA
| | - Shalini Guha
- Department of Biochemistry and Molecular Biology, Southern Illinois University School of Medicine, Carbondale, Illinois, USA
| | - Chhabi K. Govind
- Department of Biological Sciences, Oakland University, Rochester, Minnesota, USA
| | - Sukesh R. Bhaumik
- Department of Biochemistry and Molecular Biology, Southern Illinois University School of Medicine, Carbondale, Illinois, USA
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6
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Bhakat KK, Ray S. The FAcilitates Chromatin Transcription (FACT) complex: Its roles in DNA repair and implications for cancer therapy. DNA Repair (Amst) 2021; 109:103246. [PMID: 34847380 DOI: 10.1016/j.dnarep.2021.103246] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2021] [Revised: 10/07/2021] [Accepted: 11/03/2021] [Indexed: 12/17/2022]
Abstract
Genomic DNA in the nucleus is wrapped around nucleosomes, a repeating unit of chromatin. The nucleosome, consisting of octamer of core histones, is a barrier for several cellular processes that require access to the naked DNA. The FAcilitates Chromatin Transcription (FACT), a histone chaperone complex, is involved in nucleosome remodeling via eviction or assembly of histones during transcription, replication, and DNA repair. Increasing evidence suggests that FACT plays an important role in multiple DNA repair pathways including transcription-coupled nucleotide excision repair (TC-NER) of UV-induced damage, DNA single- and double-strand breaks (DSBs) repair, and base excision repair (BER) of oxidized or alkylated damaged bases. Further, studies have shown overexpression of FACT in multiple types of cancer and its association with drug resistance and patients' poor prognosis. In this review, we discuss how FACT is accumulated at the damage site and what functions it performs. We describe the known mechanisms by which FACT facilitates repair of different types of DNA damage. Further, we highlight the recent advances in a class of FACT inhibitors, called curaxins, which show promise as a new adjuvant therapy to sensitize multiple types of cancer to chemotherapy and radiation.
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Affiliation(s)
- Kishor K Bhakat
- Department of Genetics, Cell Biology and Anatomy, University of Nebraska Medical Center, Omaha, NE, USA 68198; Fred and Pamela Buffet Cancer Center, University of Nebraska Medical Center, Omaha, NE, USA 68198.
| | - Sutapa Ray
- Department of Pediatric, Division of Hematology/oncology, University of Nebraska Medical Center, Omaha, NE, USA 68198; Fred and Pamela Buffet Cancer Center, University of Nebraska Medical Center, Omaha, NE, USA 68198
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7
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Guha S, Bhaumik SR. Transcription-coupled DNA double-strand break repair. DNA Repair (Amst) 2021; 109:103211. [PMID: 34883263 DOI: 10.1016/j.dnarep.2021.103211] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2021] [Revised: 08/11/2021] [Accepted: 08/11/2021] [Indexed: 12/20/2022]
Abstract
The genomic DNA is constantly under attack by cellular and/or environmental factors. Fortunately, the cell is armed to safeguard its genome by various mechanisms such as nucleotide excision, base excision, mismatch and DNA double-strand break repairs. While these processes maintain the integrity of the genome throughout, DNA repair occurs preferentially faster at the transcriptionally active genes. Such transcription-coupled repair phenomenon plays important roles to maintain active genome integrity, failure of which would interfere with transcription, leading to an altered gene expression (and hence cellular pathologies/diseases). Among the various DNA damages, DNA double-strand breaks are quite toxic to the cells. If DNA double-strand break occurs at the active gene, it would interfere with transcription/gene expression, thus threatening cellular viability. Such DNA double-strand breaks are found to be repaired faster at the active gene in comparison to its inactive state or the inactive gene, thus supporting the existence of a new phenomenon of transcription-coupled DNA double-strand break repair. Here, we describe the advances of this repair process.
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Affiliation(s)
- Shalini Guha
- Department of Biochemistry and Molecular Biology, Southern Illinois University School of Medicine, Carbondale, IL, 62901, USA
| | - Sukesh R Bhaumik
- Department of Biochemistry and Molecular Biology, Southern Illinois University School of Medicine, Carbondale, IL, 62901, USA.
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8
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Jeronimo C, Angel A, Nguyen VQ, Kim JM, Poitras C, Lambert E, Collin P, Mellor J, Wu C, Robert F. FACT is recruited to the +1 nucleosome of transcribed genes and spreads in a Chd1-dependent manner. Mol Cell 2021; 81:3542-3559.e11. [PMID: 34380014 DOI: 10.1016/j.molcel.2021.07.010] [Citation(s) in RCA: 32] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2020] [Revised: 05/25/2021] [Accepted: 07/12/2021] [Indexed: 12/29/2022]
Abstract
The histone chaperone FACT occupies transcribed regions where it plays prominent roles in maintaining chromatin integrity and preserving epigenetic information. How it is targeted to transcribed regions, however, remains unclear. Proposed models include docking on the RNA polymerase II (RNAPII) C-terminal domain (CTD), recruitment by elongation factors, recognition of modified histone tails, and binding partially disassembled nucleosomes. Here, we systematically test these and other scenarios in Saccharomyces cerevisiae and find that FACT binds transcribed chromatin, not RNAPII. Through a combination of high-resolution genome-wide mapping, single-molecule tracking, and mathematical modeling, we propose that FACT recognizes the +1 nucleosome, as it is partially unwrapped by the engaging RNAPII, and spreads to downstream nucleosomes aided by the chromatin remodeler Chd1. Our work clarifies how FACT interacts with genes, suggests a processive mechanism for FACT function, and provides a framework to further dissect the molecular mechanisms of transcription-coupled histone chaperoning.
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Affiliation(s)
- Célia Jeronimo
- Institut de recherches cliniques de Montréal, 110 Avenue des Pins Ouest, Montréal, QC H2W 1R7, Canada
| | - Andrew Angel
- Department of Biochemistry, University of Oxford, South Parks Road, Oxford, OX1 3QU, UK
| | - Vu Q Nguyen
- Department of Biology, Johns Hopkins University, Baltimore, MD 21218, USA
| | - Jee Min Kim
- Department of Biology, Johns Hopkins University, Baltimore, MD 21218, USA
| | - Christian Poitras
- Institut de recherches cliniques de Montréal, 110 Avenue des Pins Ouest, Montréal, QC H2W 1R7, Canada
| | - Elie Lambert
- Institut de recherches cliniques de Montréal, 110 Avenue des Pins Ouest, Montréal, QC H2W 1R7, Canada
| | - Pierre Collin
- Institut de recherches cliniques de Montréal, 110 Avenue des Pins Ouest, Montréal, QC H2W 1R7, Canada
| | - Jane Mellor
- Department of Biochemistry, University of Oxford, South Parks Road, Oxford, OX1 3QU, UK
| | - Carl Wu
- Department of Biology, Johns Hopkins University, Baltimore, MD 21218, USA; Department of Molecular Biology and Genetics, Johns Hopkins School of Medicine, Baltimore, MD 21287, USA
| | - François Robert
- Institut de recherches cliniques de Montréal, 110 Avenue des Pins Ouest, Montréal, QC H2W 1R7, Canada; Département de Médecine, Faculté de Médecine, Université de Montréal, 2900 Boulevard Édouard-Montpetit, Montréal, QC H3T 1J4, Canada.
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9
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Fluorescence resonance energy transfer in revealing protein-protein interactions in living cells. Emerg Top Life Sci 2021; 5:49-59. [PMID: 33856021 DOI: 10.1042/etls20200337] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2020] [Revised: 02/22/2021] [Accepted: 03/04/2021] [Indexed: 11/17/2022]
Abstract
Genes are expressed to proteins for a wide variety of fundamental biological processes at the cellular and organismal levels. However, a protein rarely functions alone, but rather acts through interactions with other proteins to maintain normal cellular and organismal functions. Therefore, it is important to analyze the protein-protein interactions to determine functional mechanisms of proteins, which can also guide to develop therapeutic targets for treatment of diseases caused by altered protein-protein interactions leading to cellular/organismal dysfunctions. There is a large number of methodologies to study protein interactions in vitro, in vivo and in silico, which led to the development of many protein interaction databases, and thus, have enriched our knowledge about protein-protein interactions and functions. However, many of these interactions were identified in vitro, but need to be verified/validated in living cells. Furthermore, it is unclear whether these interactions are direct or mediated via other proteins. Moreover, these interactions are representative of cell- and time-average, but not a single cell in real time. Therefore, it is crucial to detect direct protein-protein interactions in a single cell during biological processes in vivo, towards understanding the functional mechanisms of proteins in living cells. Importantly, a fluorescence resonance energy transfer (FRET)-based methodology has emerged as a powerful technique to decipher direct protein-protein interactions at a single cell resolution in living cells, which is briefly described in a limited available space in this mini-review.
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Proteasomal Regulation of Mammalian SPT16 in Controlling Transcription. Mol Cell Biol 2021; 41:MCB.00452-20. [PMID: 33526453 DOI: 10.1128/mcb.00452-20] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2020] [Accepted: 01/22/2021] [Indexed: 02/07/2023] Open
Abstract
FACT (facilitates chromatin transcription), an essential and evolutionarily conserved heterodimer from yeast to humans, controls transcription and is found to be upregulated in various cancers. However, the basis for such upregulation is not clearly understood. Our recent results deciphering a new ubiquitin-proteasome system regulation of the FACT subunit SPT16 in orchestrating transcription in yeast hint at the involvement of the proteasome in controlling FACT in humans, with a link to cancer. To test this, we carried out experiments in human embryonic kidney (HEK293) cells, which revealed that human SPT16 undergoes ubiquitylation and that its abundance is increased following inhibition of the proteolytic activity of the proteasome, thus implying proteasomal regulation of human SPT16. Furthermore, we find that the increased abundance/expression of SPT16 in HEK293 cells alters the transcription of genes, including ones associated with cancer, and that the proteasomal degradation of SPT16 is impaired in kidney cancer (Caki-2) cells to upregulate SPT16. Like human SPT16, murine SPT16 in C2C12 cells also undergoes ubiquitylation and proteasomal degradation to regulate transcription. Collectively, our results reveal a proteasomal regulation of mammalian SPT16, with physiological relevance in controlling transcription, and implicate such proteasomal control in the upregulation of SPT16 in cancer.
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11
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Interplay of mRNA capping and transcription machineries. Biosci Rep 2021; 40:221784. [PMID: 31904821 PMCID: PMC6981093 DOI: 10.1042/bsr20192825] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2019] [Revised: 01/02/2020] [Accepted: 01/06/2020] [Indexed: 12/31/2022] Open
Abstract
Early stages of transcription from eukaryotic promoters include two principal events: the capping of newly synthesized mRNA and the transition of RNA polymerase II from the preinitiation complex to the productive elongation state. The capping checkpoint model implies that these events are tightly coupled, which is necessary for ensuring the proper capping of newly synthesized mRNA. Recent findings also show that the capping machinery has a wider effect on transcription and the entire gene expression process. The molecular basis of these phenomena is discussed.
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Guha S, Bhaumik SR. Viral regulation of mRNA export with potentials for targeted therapy. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2020; 1864:194655. [PMID: 33246183 DOI: 10.1016/j.bbagrm.2020.194655] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Received: 07/04/2020] [Revised: 10/15/2020] [Accepted: 11/05/2020] [Indexed: 12/12/2022]
Abstract
Eukaryotic gene expression begins with transcription in the nucleus to synthesize mRNA (messenger RNA), which is subsequently exported to the cytoplasm for translation to protein. Like transcription and translation, mRNA export is an important regulatory step of eukaryotic gene expression. Various factors are involved in regulating mRNA export, and thus gene expression. Intriguingly, some of these factors interact with viral proteins, and such interactions interfere with mRNA export of the host cell, favoring viral RNA export. Hence, viruses hijack host mRNA export machinery for export of their own RNAs from nucleus to cytoplasm for translation to proteins for viral life cycle, suppressing host mRNA export (and thus host gene expression and immune/antiviral response). Therefore, the molecules that can impair the interactions of these mRNA export factors with viral proteins could emerge as antiviral therapeutic agents to suppress viral RNA transport and enhance host mRNA export, thereby promoting host gene expression and immune response. Thus, there has been a number of studies to understand how virus hijacks mRNA export machinery in suppressing host gene expression and promoting its own RNA export to the cytoplasm for translation to proteins required for viral replication/assembly/life cycle towards developing targeted antiviral therapies, as concisely described here.
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Affiliation(s)
- Shalini Guha
- Department of Biochemistry and Molecular Biology, Southern Illinois University School of Medicine, Carbondale, IL 62901, USA
| | - Sukesh R Bhaumik
- Department of Biochemistry and Molecular Biology, Southern Illinois University School of Medicine, Carbondale, IL 62901, USA.
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Tellier M, Maudlin I, Murphy S. Transcription and splicing: A two-way street. WILEY INTERDISCIPLINARY REVIEWS. RNA 2020; 11:e1593. [PMID: 32128990 DOI: 10.1002/wrna.1593] [Citation(s) in RCA: 49] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/22/2019] [Revised: 12/18/2019] [Accepted: 02/12/2020] [Indexed: 12/11/2022]
Abstract
RNA synthesis by RNA polymerase II and RNA processing are closely coupled during the transcription cycle of protein-coding genes. This coupling affords opportunities for quality control and regulation of gene expression and the effects can go in both directions. For example, polymerase speed can affect splice site selection and splicing can increase transcription and affect the chromatin landscape. Here we review the many ways that transcription and splicing influence one another, including how splicing "talks back" to transcription. We will also place the connections between transcription and splicing in the context of other RNA processing events that define the exons that will make up the final mRNA. This article is categorized under: RNA Processing > Splicing Mechanisms RNA Processing > Splicing Regulation/Alternative Splicing.
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Affiliation(s)
- Michael Tellier
- Sir William Dunn School of Pathology, University of Oxford, Oxford, UK
| | - Isabella Maudlin
- Sir William Dunn School of Pathology, University of Oxford, Oxford, UK
| | - Shona Murphy
- Sir William Dunn School of Pathology, University of Oxford, Oxford, UK
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Ipa1 Is an RNA Polymerase II Elongation Factor that Facilitates Termination by Maintaining Levels of the Poly(A) Site Endonuclease Ysh1. Cell Rep 2020; 26:1919-1933.e5. [PMID: 30759400 PMCID: PMC7236606 DOI: 10.1016/j.celrep.2019.01.051] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2018] [Revised: 12/05/2018] [Accepted: 01/15/2019] [Indexed: 02/08/2023] Open
Abstract
The yeast protein Ipa1 was recently discovered to interact with the Ysh1
endonuclease of the prem-RNA cleavage and polyadenylation (C/P) machinery, and
Ipa1 mutation impairs 3′end processing. We report that Ipa1 globally
promotes proper transcription termination and poly(A) site selection, but with
variable effects on genes depending upon the specific configurations of
polyadenylation signals. Our findings suggest that the role of Ipa1 in
termination is mediated through interaction with Ysh1, since Ipa1 mutation leads
to decrease in Ysh1 and poor recruitment of the C/P complex to a transcribed
gene. The Ipa1 association with transcriptionally active chromatin resembles
that of elongation factors, and the mutant shows defective Pol II elongation
kinetics in vivo. Ysh1 overexpression in the Ipa1 mutant
rescues the termination defect, but not the mutant’s sensitivity to
6-azauracil, an indicator of defective elongation. Our findings support a model
in which an Ipa1/Ysh1 complex helps coordinate transcription elongation and
3′ end processing. The essential, uncharacterized Ipa1 protein was recently discovered to
interact with the Ysh1 endonuclease of the pre-mRNA cleavage and polyadenylation
machinery. Pearson et al. propose that the Ipa1/Ysh1 interaction provides the
cell with a means to coordinate and regulate transcription elongation with
3′ end processing in accordance with the cell’s needs.
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15
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An F-Box Protein, Mdm30, Interacts with TREX Subunit Sub2 To Regulate Cellular Abundance Cotranscriptionally in Orchestrating mRNA Export Independently of Splicing and Mitochondrial Function. Mol Cell Biol 2020; 40:MCB.00570-19. [PMID: 31932480 DOI: 10.1128/mcb.00570-19] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2019] [Accepted: 01/03/2020] [Indexed: 02/02/2023] Open
Abstract
Although an F-box protein, Mdm30, is found to regulate ubiquitylation of the Sub2 component of TREX (transcription-export) complex for proteasomal degradation in stimulation of mRNA export, it remains unknown whether such ubiquitin-proteasome system (UPS) regulation of Sub2 occurs cotranscriptionally via its interaction with Mdm30. Further, it is unclear whether impaired UPS regulation of Sub2 in the absence of Mdm30 alters mRNA export via splicing defects of export factors and/or mitochondrial dynamics/function, since Sub2 controls mRNA splicing and Mdm30 regulates mitochondrial aggregation. Here, we show that Mdm30 interacts with Sub2, and temporary shutdown of Mdm30 enhances Sub2's abundance and impairs mRNA export. Likewise, Sub2's abundance is increased following transcriptional inhibition. These results support Mdm30's direct role in regulation of Sub2's cellular abundance in a transcription-dependent manner. Consistently, the chromatin-bound Sub2 level is increased in the absence of Mdm30. Further, we find that Mdm30 does not facilitate splicing of export factors. Moreover, Mdm30 does not have a dramatic effect on mitochondrial respiration/function, and mRNA export occurs in the absence of Fzo1, which is required for mitochondrial dynamics/respiration. Collective results reveal that Mdm30 interacts with Sub2 for proteasomal degradation in a transcription-dependent manner to promote mRNA export independently of splicing or mitochondrial function, thus advancing our understanding of mRNA export.
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Campbell JB, Edwards MJ, Ozersky SA, Duina AA. Evidence that dissociation of Spt16 from transcribed genes is partially dependent on RNA Polymerase II termination. Transcription 2019; 10:195-206. [PMID: 31809228 PMCID: PMC6948958 DOI: 10.1080/21541264.2019.1685837] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
FACT (FAcilitates Chromatin Transactions) is a highly conserved histone chaperone complex in eukaryotic cells that can interact and manipulate nucleosomes in order to promote a variety of DNA-based processes and to maintain the integrity of chromatin throughout the genome. Whereas key features of the physical interactions that occur between FACT and nucleosomes in vitro have been elucidated in recent years, less is known regarding FACT functional dynamics in vivo. Using the Saccharomyces cerevisiae system, we now provide evidence that at least at some genes dissociation of the FACT subunit Spt16 from their 3′ ends is partially dependent on RNA Polymerase II (Pol II) termination. Combined with other studies, our results are consistent with a two-phase mechanism for FACT dissociation from genes, one that occurs upstream from Pol II dissociation and is Pol II termination-independent and the other that occurs further downstream and is dependent on Pol II termination.
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Affiliation(s)
| | | | | | - Andrea A Duina
- Biology Department, Hendrix College, Conway, Arkansas, USA
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17
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Martin BJE, Chruscicki AT, Howe LJ. Transcription Promotes the Interaction of the FAcilitates Chromatin Transactions (FACT) Complex with Nucleosomes in Saccharomyces cerevisiae. Genetics 2018; 210:869-881. [PMID: 30237209 PMCID: PMC6218215 DOI: 10.1534/genetics.118.301349] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2018] [Accepted: 09/06/2018] [Indexed: 12/20/2022] Open
Abstract
The FACT (FAcilitates Chromatin Transactions) complex is a conserved complex that maintains chromatin structure on transcriptionally active genes. Consistent with this, FACT is enriched on highly expressed genes, but how it is targeted to these regions is unknown. In vitro, FACT binds destabilized nucleosomes, supporting the hypothesis that FACT is targeted to transcribed chromatin through recognition of RNA polymerase (RNAP)-disrupted nucleosomes. In this study, we used high-resolution analysis of FACT occupancy in Saccharomyces cerevisiae to test this hypothesis. We demonstrate that FACT interacts with nucleosomes in vivo and that its interaction with chromatin is dependent on transcription by any of the three RNAPs. Deep sequencing of micrococcal nuclease-resistant fragments shows that FACT-bound nucleosomes exhibit differing nuclease sensitivity compared to bulk chromatin, consistent with a modified nucleosome structure being the preferred ligand for this complex. Interestingly, a subset of FACT-bound nucleosomes may be "overlapping dinucleosomes," in which one histone octamer invades the ∼147-bp territory normally occupied by the adjacent nucleosome. While the differing nuclease sensitivity of FACT-bound nucleosomes could also be explained by the demonstrated ability of FACT to alter nucleosome structure, transcription inhibition restores nuclease resistance, suggesting that it is not due to FACT interaction alone. Collectively, these results are consistent with a model in which FACT is targeted to transcribed genes through preferential interaction with RNAP-disrupted nucleosomes.
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Affiliation(s)
- Benjamin J E Martin
- Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, British Columbia V6T 1Z3, Canada
| | - Adam T Chruscicki
- Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, British Columbia V6T 1Z3, Canada
| | - LeAnn J Howe
- Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, British Columbia V6T 1Z3, Canada
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18
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Karmakar S, Dey P, Vaz AP, Bhaumik SR, Ponnusamy MP, Batra SK. PD2/PAF1 at the Crossroads of the Cancer Network. Cancer Res 2018; 78:313-319. [PMID: 29311159 DOI: 10.1158/0008-5472.can-17-2175] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2017] [Revised: 09/29/2017] [Accepted: 11/06/2017] [Indexed: 12/31/2022]
Abstract
Pancreatic differentiation 2 (PD2)/RNA polymerase II-associated factor 1 (PAF1) is the core subunit of the human PAF1 complex (PAF1C) that regulates the promoter-proximal pausing of RNA polymerase II as well as transcription elongation and mRNA processing and coordinates events in mRNA stability and quality control. As an integral part of its transcription-regulatory function, PD2/PAF1 plays a role in posttranslational histone covalent modifications as well as regulates expression of critical genes of the cell-cycle machinery. PD2/PAF1 alone, and as a part of PAF1C, provides distinct roles in the maintenance of self-renewal of embryonic stem cells and cancer stem cells, and in lineage differentiation. Thus, PD2/PAF1 malfunction or its altered abundance is likely to affect normal cellular functions, leading to disease states. Indeed, PD2/PAF1 is found to be upregulated in poorly differentiated pancreatic cancer cells and has the capacity for neoplastic transformation when ectopically expressed in mouse fibroblast cells. Likewise, PD2/PAF1 is upregulated in pancreatic and ovarian cancer stem cells. Here, we concisely describe multifaceted roles of PD2/PAF1 associated with oncogenic transformation and implicate PD2/PAF1 as an attractive target for therapeutic development to combat malignancy. Cancer Res; 78(2); 313-9. ©2018 AACR.
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Affiliation(s)
- Saswati Karmakar
- Department of Biochemistry and Molecular Biology, University of Nebraska Medical Center, Omaha, Nebraska
| | - Parama Dey
- Department of Biochemistry and Molecular Biology, University of Nebraska Medical Center, Omaha, Nebraska
| | - Arokia P Vaz
- Department of Biochemistry and Molecular Biology, University of Nebraska Medical Center, Omaha, Nebraska
| | - Sukesh R Bhaumik
- Department of Biochemistry and Molecular Biology, Southern Illinois University School of Medicine, Carbondale, Illinois
| | - Moorthy P Ponnusamy
- Department of Biochemistry and Molecular Biology, University of Nebraska Medical Center, Omaha, Nebraska.,Eppley Institute for Research in Cancer and Allied Diseases and Buffett Cancer Center, University of Nebraska Medical Center, Omaha, Nebraska
| | - Surinder K Batra
- Department of Biochemistry and Molecular Biology, University of Nebraska Medical Center, Omaha, Nebraska. .,Eppley Institute for Research in Cancer and Allied Diseases and Buffett Cancer Center, University of Nebraska Medical Center, Omaha, Nebraska
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