1
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Senn KA, Hoskins AA. Mechanisms and regulation of spliceosome-mediated pre-mRNA splicing in Saccharomyces cerevisiae. WILEY INTERDISCIPLINARY REVIEWS. RNA 2024; 15:e1866. [PMID: 38972853 DOI: 10.1002/wrna.1866] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/05/2024] [Revised: 05/19/2024] [Accepted: 05/28/2024] [Indexed: 07/09/2024]
Abstract
Pre-mRNA splicing, the removal of introns and ligation of flanking exons, is a crucial step in eukaryotic gene expression. The spliceosome, a macromolecular complex made up of five small nuclear RNAs (snRNAs) and dozens of proteins, assembles on introns via a complex pathway before catalyzing the two transesterification reactions necessary for splicing. All of these steps have the potential to be highly regulated to ensure correct mRNA isoform production for proper cellular function. While Saccharomyces cerevisiae (yeast) has a limited set of intron-containing genes, many of these genes are highly expressed, resulting in a large number of transcripts in a cell being spliced. As a result, splicing regulation is of critical importance for yeast. Just as in humans, yeast splicing can be influenced by protein components of the splicing machinery, structures and properties of the pre-mRNA itself, or by the action of trans-acting factors. It is likely that further analysis of the mechanisms and pathways of splicing regulation in yeast can reveal general principles applicable to other eukaryotes. This article is categorized under: RNA Processing > Splicing Mechanisms RNA Processing > Splicing Regulation/Alternative Splicing.
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Affiliation(s)
- Katherine Anne Senn
- Department of Biochemistry, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - Aaron A Hoskins
- Department of Biochemistry, University of Wisconsin-Madison, Madison, Wisconsin, USA
- Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin, USA
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2
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Sengupta S, Pick E. The Ubiquitin-like Proteins of Saccharomyces cerevisiae. Biomolecules 2023; 13:biom13050734. [PMID: 37238603 DOI: 10.3390/biom13050734] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2023] [Revised: 04/18/2023] [Accepted: 04/21/2023] [Indexed: 05/28/2023] Open
Abstract
In this review, we present a comprehensive list of the ubiquitin-like modifiers (Ubls) of Saccharomyces cerevisiae, a common model organism used to study fundamental cellular processes that are conserved in complex multicellular organisms, such as humans. Ubls are a family of proteins that share structural relationships with ubiquitin, and which modify target proteins and lipids. These modifiers are processed, activated and conjugated to substrates by cognate enzymatic cascades. The attachment of substrates to Ubls alters the various properties of these substrates, such as function, interaction with the environment or turnover, and accordingly regulate key cellular processes, including DNA damage, cell cycle progression, metabolism, stress response, cellular differentiation, and protein homeostasis. Thus, it is not surprising that Ubls serve as tools to study the underlying mechanism involved in cellular health. We summarize current knowledge on the activity and mechanism of action of the S. cerevisiae Rub1, Smt3, Atg8, Atg12, Urm1 and Hub1 modifiers, all of which are highly conserved in organisms from yeast to humans.
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Affiliation(s)
- Swarnab Sengupta
- Department of Evolutionary and Environmental Biology, Faculty of Natural Sciences, University of Haifa Mount Carmel, Haifa 3498838, Israel
| | - Elah Pick
- Department of Evolutionary and Environmental Biology, Faculty of Natural Sciences, University of Haifa Mount Carmel, Haifa 3498838, Israel
- Department of Biology and Environment, Faculty of Natural Sciences, University of Haifa, Oranim, Tivon 3600600, Israel
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3
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Martín Caballero L, Capella M, Barrales RR, Dobrev N, van Emden T, Hirano Y, Suma Sreechakram VN, Fischer-Burkart S, Kinugasa Y, Nevers A, Rougemaille M, Sinning I, Fischer T, Hiraoka Y, Braun S. The inner nuclear membrane protein Lem2 coordinates RNA degradation at the nuclear periphery. Nat Struct Mol Biol 2022; 29:910-921. [PMID: 36123402 PMCID: PMC9507967 DOI: 10.1038/s41594-022-00831-6] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2021] [Accepted: 08/02/2022] [Indexed: 11/21/2022]
Abstract
Transcriptionally silent chromatin often localizes to the nuclear periphery. However, whether the nuclear envelope (NE) is a site for post-transcriptional gene repression is not well understood. Here we demonstrate that Schizosaccharomycespombe Lem2, an NE protein, regulates nuclear-exosome-mediated RNA degradation. Lem2 deletion causes accumulation of RNA precursors and meiotic transcripts and de-localization of an engineered exosome substrate from the nuclear periphery. Lem2 does not directly bind RNA but instead interacts with the exosome-targeting MTREC complex and its human homolog PAXT to promote RNA recruitment. This pathway acts largely independently of nuclear bodies where exosome factors assemble. Nutrient availability modulates Lem2 regulation of meiotic transcripts, implying that this pathway is environmentally responsive. Our work reveals that multiple spatially distinct degradation pathways exist. Among these, Lem2 coordinates RNA surveillance of meiotic transcripts and non-coding RNAs by recruiting exosome co-factors to the nuclear periphery. The Braun lab shows that the conserved nuclear membrane protein Lem2 interacts with the MTREC complex of the nuclear-exosome pathway to promote recruitment and degradation of ncRNAs and meiotic transcripts at the nuclear periphery in Schizosaccharomycespombe.
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Affiliation(s)
- Lucía Martín Caballero
- BioMedical Center (BMC), Division of Physiological Chemistry, Faculty of Medicine, LMU Munich, Planegg-Martinsried, Germany.,International Max Planck Research School for Molecular and Cellular Life Sciences, Planegg-Martinsried, Germany
| | - Matías Capella
- BioMedical Center (BMC), Division of Physiological Chemistry, Faculty of Medicine, LMU Munich, Planegg-Martinsried, Germany.,Instituto de Agrobiotecnología del Litoral, CONICET, Universidad Nacional del Litoral, Santa Fe, Argentina
| | - Ramón Ramos Barrales
- BioMedical Center (BMC), Division of Physiological Chemistry, Faculty of Medicine, LMU Munich, Planegg-Martinsried, Germany.,Centro Andaluz de Biología del Desarrollo (CABD), Universidad Pablo de Olavide-Consejo Superior de Investigaciones Científicas-Junta de Andalucía, Seville, Spain
| | - Nikolay Dobrev
- Heidelberg University Biochemistry Center (BZH), Heidelberg, Germany.,European Molecular Biology Laboratory, Hamburg Unit, Hamburg, Germany
| | - Thomas van Emden
- BioMedical Center (BMC), Division of Physiological Chemistry, Faculty of Medicine, LMU Munich, Planegg-Martinsried, Germany.,International Max Planck Research School for Molecular and Cellular Life Sciences, Planegg-Martinsried, Germany
| | - Yasuhiro Hirano
- Graduate School of Frontier Biosciences, Osaka University, Suita, Japan
| | - Vishnu N Suma Sreechakram
- BioMedical Center (BMC), Division of Physiological Chemistry, Faculty of Medicine, LMU Munich, Planegg-Martinsried, Germany.,Institute for Genetics, Justus-Liebig-University Giessen, Giessen, Germany
| | - Sabine Fischer-Burkart
- BioMedical Center (BMC), Division of Physiological Chemistry, Faculty of Medicine, LMU Munich, Planegg-Martinsried, Germany
| | - Yasuha Kinugasa
- Graduate School of Frontier Biosciences, Osaka University, Suita, Japan.,Regulation for intractable Infectious Diseases, National Institutes of Biomedical Innovation, Health and Nutrition, Ibaraki, Japan
| | - Alicia Nevers
- Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), Gif-sur-Yvette, France.,University Paris-Saclay, INRAE, AgroParisTech, Micalis Institute, Jouy-en-Josas, France
| | - Mathieu Rougemaille
- Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), Gif-sur-Yvette, France
| | - Irmgard Sinning
- Heidelberg University Biochemistry Center (BZH), Heidelberg, Germany
| | - Tamás Fischer
- Heidelberg University Biochemistry Center (BZH), Heidelberg, Germany.,The John Curtin School of Medical Research, The Australian National University, Canberra, Australian Capital Territory, Australia
| | - Yasushi Hiraoka
- Graduate School of Frontier Biosciences, Osaka University, Suita, Japan
| | - Sigurd Braun
- BioMedical Center (BMC), Division of Physiological Chemistry, Faculty of Medicine, LMU Munich, Planegg-Martinsried, Germany. .,International Max Planck Research School for Molecular and Cellular Life Sciences, Planegg-Martinsried, Germany. .,Institute for Genetics, Justus-Liebig-University Giessen, Giessen, Germany.
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4
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The ESCRT Machinery: Remodeling, Repairing, and Sealing Membranes. MEMBRANES 2022; 12:membranes12060633. [PMID: 35736340 PMCID: PMC9229795 DOI: 10.3390/membranes12060633] [Citation(s) in RCA: 23] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/11/2022] [Revised: 06/16/2022] [Accepted: 06/17/2022] [Indexed: 01/27/2023]
Abstract
The ESCRT machinery is an evolutionarily conserved membrane remodeling complex that is used by the cell to perform reverse membrane scission in essential processes like protein degradation, cell division, and release of enveloped retroviruses. ESCRT-III, together with the AAA ATPase VPS4, harbors the main remodeling and scission function of the ESCRT machinery, whereas early-acting ESCRTs mainly contribute to protein sorting and ESCRT-III recruitment through association with upstream targeting factors. Here, we review recent advances in our understanding of the molecular mechanisms that underlie membrane constriction and scission by ESCRT-III and describe the involvement of this machinery in the sealing and repairing of damaged cellular membranes, a key function to preserve cellular viability and organellar function.
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5
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Dultz E, Wojtynek M, Medalia O, Onischenko E. The Nuclear Pore Complex: Birth, Life, and Death of a Cellular Behemoth. Cells 2022; 11:1456. [PMID: 35563762 PMCID: PMC9100368 DOI: 10.3390/cells11091456] [Citation(s) in RCA: 30] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2022] [Revised: 04/22/2022] [Accepted: 04/23/2022] [Indexed: 02/01/2023] Open
Abstract
Nuclear pore complexes (NPCs) are the only transport channels that cross the nuclear envelope. Constructed from ~500-1000 nucleoporin proteins each, they are among the largest macromolecular assemblies in eukaryotic cells. Thanks to advances in structural analysis approaches, the construction principles and architecture of the NPC have recently been revealed at submolecular resolution. Although the overall structure and inventory of nucleoporins are conserved, NPCs exhibit significant compositional and functional plasticity even within single cells and surprising variability in their assembly pathways. Once assembled, NPCs remain seemingly unexchangeable in post-mitotic cells. There are a number of as yet unresolved questions about how the versatility of NPC assembly and composition is established, how cells monitor the functional state of NPCs or how they could be renewed. Here, we review current progress in our understanding of the key aspects of NPC architecture and lifecycle.
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Affiliation(s)
- Elisa Dultz
- Institute of Biochemistry, Department of Biology, ETHZ Zurich, 8093 Zurich, Switzerland;
| | - Matthias Wojtynek
- Institute of Biochemistry, Department of Biology, ETHZ Zurich, 8093 Zurich, Switzerland;
- Department of Biochemistry, University of Zurich, 8057 Zurich, Switzerland;
| | - Ohad Medalia
- Department of Biochemistry, University of Zurich, 8057 Zurich, Switzerland;
| | - Evgeny Onischenko
- Department of Biological Sciences, University of Bergen, 5020 Bergen, Norway
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6
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Shankar R, Lettman MM, Whisler W, Frankel EB, Audhya A. The ESCRT machinery directs quality control over inner nuclear membrane architecture. Cell Rep 2022; 38:110263. [PMID: 35045304 PMCID: PMC8801257 DOI: 10.1016/j.celrep.2021.110263] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2021] [Revised: 11/21/2021] [Accepted: 12/21/2021] [Indexed: 11/20/2022] Open
Abstract
The late-acting endosomal sorting complex required for transport (ESCRT) machinery has been implicated in facilitating the resealing of the nuclear envelope (NE) after mitosis, enabling compartmentalization of the genome away from the cytoplasm. Here, we leverage the stereotypic first division of the C. elegans embryo to identify additional functions of the ESCRT machinery in maintaining the structure of the inner nuclear membrane. Specifically, impaired ESCRT function results in a defect in the pruning of inner nuclear membrane invaginations, which arise normally during NE reformation and expansion. Additionally, in combination with a hypomorphic mutation that interferes with assembly of the underlying nuclear lamina, inhibition of ESCRT function significantly perturbs NE architecture and increases chromosome segregation defects, resulting in penetrant embryonic lethality. Our findings highlight links between ESCRT-mediated inner nuclear membrane remodeling, maintenance of nuclear envelope morphology, and the preservation of the genome during early development. In this study, Shankar et al. demonstrate that defects in ESCRT machinery functions impair pruning of inner nuclear membrane invaginations that form normally after mitotic exit as the nuclear envelope undergoes expansion. These findings highlight a critical role for the ESCRT machinery in the maintenance of inner nuclear membrane morphology.
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Affiliation(s)
- Raakhee Shankar
- Department of Biomolecular Chemistry, University of Wisconsin School of Medicine and Public Health, Madison, WI 53705, USA
| | - Molly M Lettman
- Department of Biomolecular Chemistry, University of Wisconsin School of Medicine and Public Health, Madison, WI 53705, USA
| | - William Whisler
- Department of Biomolecular Chemistry, University of Wisconsin School of Medicine and Public Health, Madison, WI 53705, USA
| | - Elisa B Frankel
- Department of Biomolecular Chemistry, University of Wisconsin School of Medicine and Public Health, Madison, WI 53705, USA
| | - Anjon Audhya
- Department of Biomolecular Chemistry, University of Wisconsin School of Medicine and Public Health, Madison, WI 53705, USA.
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7
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Hassell DS, Steingesser MG, Denney AS, Johnson CR, McMurray MA. Chemical rescue of mutant proteins in living Saccharomyces cerevisiae cells by naturally occurring small molecules. G3-GENES GENOMES GENETICS 2021; 11:6323229. [PMID: 34544143 PMCID: PMC8496222 DOI: 10.1093/g3journal/jkab252] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/16/2021] [Accepted: 06/29/2021] [Indexed: 11/14/2022]
Abstract
Intracellular proteins function in a complex milieu wherein small molecules influence protein folding and act as essential cofactors for enzymatic reactions. Thus protein function depends not only on amino acid sequence but also on the concentrations of such molecules, which are subject to wide variation between organisms, metabolic states, and environmental conditions. We previously found evidence that exogenous guanidine reverses the phenotypes of specific budding yeast septin mutants by binding to a WT septin at the former site of an Arg side chain that was lost during fungal evolution. Here, we used a combination of targeted and unbiased approaches to look for other cases of "chemical rescue" by naturally occurring small molecules. We report in vivo rescue of hundreds of Saccharomyces cerevisiae mutants representing a variety of genes, including likely examples of Arg or Lys side chain replacement by the guanidinium ion. Failed rescue of targeted mutants highlight features required for rescue, as well as key differences between the in vitro and in vivo environments. Some non-Arg mutants rescued by guanidine likely result from "off-target" effects on specific cellular processes in WT cells. Molecules isosteric to guanidine and known to influence protein folding had a range of effects, from essentially none for urea, to rescue of a few mutants by DMSO. Strikingly, the osmolyte trimethylamine-N-oxide rescued ∼20% of the mutants we tested, likely reflecting combinations of direct and indirect effects on mutant protein function. Our findings illustrate the potential of natural small molecules as therapeutic interventions and drivers of evolution.
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Affiliation(s)
- Daniel S Hassell
- Department of Cell and Developmental Biology, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA
| | - Marc G Steingesser
- Department of Cell and Developmental Biology, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA
| | - Ashley S Denney
- Department of Cell and Developmental Biology, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA
| | - Courtney R Johnson
- Department of Cell and Developmental Biology, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA
| | - Michael A McMurray
- Department of Cell and Developmental Biology, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA
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8
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Chanarat S. UBL5/Hub1: An Atypical Ubiquitin-Like Protein with a Typical Role as a Stress-Responsive Regulator. Int J Mol Sci 2021; 22:ijms22179384. [PMID: 34502293 PMCID: PMC8431670 DOI: 10.3390/ijms22179384] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2021] [Revised: 08/25/2021] [Accepted: 08/29/2021] [Indexed: 11/23/2022] Open
Abstract
Members of the ubiquitin-like protein family are known for their ability to modify substrates by covalent conjugation. The highly conserved ubiquitin relative UBL5/Hub1, however, is atypical because it lacks a carboxy-terminal di-glycine motif required for conjugation, and the whole E1-E2-E3 enzyme cascade is likely absent. Though the conjugation-mediated role of UBL5/Hub1 is controversial, it undoubtedly functions by interacting non-covalently with its partners. Several interactors of UBL5/Hub1 identified to date have suggested broad stress-responsive functions of the protein, for example, stress-induced control of pre-mRNA splicing, Fanconi anemia pathway of DNA damage repair, and mitochondrial unfolded protein response. While having an atypical mode of function, UBL5/Hub1 is still a stress protein that regulates feedback to various stimuli in a similar manner to other ubiquitin-like proteins. In this review, I discuss recent progress in understanding the functions of UBL5/Hub1 and the fundamental questions which remain to be answered.
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Affiliation(s)
- Sittinan Chanarat
- Laboratory of Molecular Cell Biology, Department of Biochemistry and Center for Excellence in Protein and Enzyme Technology, Faculty of Science, Mahidol University, Bangkok 10400, Thailand
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9
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Nucleolar release of rDNA repeats for repair involves SUMO-mediated untethering by the Cdc48/p97 segregase. Nat Commun 2021; 12:4918. [PMID: 34389719 PMCID: PMC8363623 DOI: 10.1038/s41467-021-25205-2] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2021] [Accepted: 07/20/2021] [Indexed: 12/12/2022] Open
Abstract
Ribosomal RNA genes (rDNA) are highly unstable and susceptible to rearrangement due to their repetitive nature and active transcriptional status. Sequestration of rDNA in the nucleolus suppresses uncontrolled recombination. However, broken repeats must be first released to the nucleoplasm to allow repair by homologous recombination. Nucleolar release of broken rDNA repeats is conserved from yeast to humans, but the underlying molecular mechanisms are currently unknown. Here we show that DNA damage induces phosphorylation of the CLIP-cohibin complex, releasing membrane-tethered rDNA from the nucleolus in Saccharomyces cerevisiae. Downstream of phosphorylation, SUMOylation of CLIP-cohibin is recognized by Ufd1 via its SUMO-interacting motif, which targets the complex for disassembly through the Cdc48/p97 chaperone. Consistent with a conserved mechanism, UFD1L depletion in human cells impairs rDNA release. The dynamic and regulated assembly and disassembly of the rDNA-tethering complex is therefore a key determinant of nucleolar rDNA release and genome integrity.
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10
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Adding Some "Splice" to Stress Eating: Autophagy, ESCRT and Alternative Splicing Orchestrate the Cellular Stress Response. Genes (Basel) 2021; 12:genes12081196. [PMID: 34440370 PMCID: PMC8393842 DOI: 10.3390/genes12081196] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2021] [Revised: 07/29/2021] [Accepted: 07/30/2021] [Indexed: 12/12/2022] Open
Abstract
Autophagy is a widely studied self-renewal pathway that is essential for degrading damaged cellular organelles or recycling biomolecules to maintain cellular homeostasis, particularly under cellular stress. This pathway initiates with formation of an autophagosome, which is a double-membrane structure that envelopes cytosolic components and fuses with a lysosome to facilitate degradation of the contents. The endosomal sorting complexes required for transport (ESCRT) proteins play an integral role in controlling autophagosome fusion events and disruption to this machinery leads to autophagosome accumulation. Given the central role of autophagy in maintaining cellular health, it is unsurprising that dysfunction of this process is associated with many human maladies including cancer and neurodegenerative diseases. The cell can also rapidly respond to cellular stress through alternative pre-mRNA splicing that enables adaptive changes to the cell's proteome in response to stress. Thus, alternative pre-mRNA splicing of genes that are involved in autophagy adds another layer of complexity to the cell's stress response. Consequently, the dysregulation of alternative splicing of genes associated with autophagy and ESCRT may also precipitate disease states by either reducing the ability of the cell to respond to stress or triggering a maladaptive response that is pathogenic. In this review, we summarize the diverse roles of the ESCRT machinery and alternative splicing in regulating autophagy and how their dysfunction can have implications for human disease.
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First person – Matías Capella. J Cell Sci 2020. [DOI: 10.1242/jcs.258020] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
ABSTRACT
First Person is a series of interviews with the first authors of a selection of papers published in Journal of Cell Science, helping early-career researchers promote themselves alongside their papers. Matías Capella is first author on ‘ ESCRT recruitment by the S. cerevisiae inner nuclear membrane protein Heh1 is regulated by Hub1-mediated alternative splicing’, published in JCS. Matías conducted the research described in this article while a postdoc in Prof. Dr Stefan Jentsch's lab at the Max Planck Institute of Biochemistry, Munich, Germany. He is now a postdoc in the lab of Dr Sigurd Braun at the Biomedical Center Munich, Ludwig-Maximilians-Universität, Munich, investigating the regulation of repetitive DNA stability.
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