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Cell Nov 2017YAP is a mechanosensitive transcriptional activator with a critical role in cancer, regeneration, and organ size control. Here, we show that force applied to the nucleus...
YAP is a mechanosensitive transcriptional activator with a critical role in cancer, regeneration, and organ size control. Here, we show that force applied to the nucleus directly drives YAP nuclear translocation by decreasing the mechanical restriction of nuclear pores to molecular transport. Exposure to a stiff environment leads cells to establish a mechanical connection between the nucleus and the cytoskeleton, allowing forces exerted through focal adhesions to reach the nucleus. Force transmission then leads to nuclear flattening, which stretches nuclear pores, reduces their mechanical resistance to molecular transport, and increases YAP nuclear import. The restriction to transport is further regulated by the mechanical stability of the transported protein, which determines both active nuclear transport of YAP and passive transport of small proteins. Our results unveil a mechanosensing mechanism mediated directly by nuclear pores, demonstrated for YAP but with potential general applicability in transcriptional regulation.
Topics: Active Transport, Cell Nucleus; Adaptor Proteins, Signal Transducing; Animals; Biomechanical Phenomena; Cell Cycle Proteins; Cell Line, Tumor; Cell Nucleus; Humans; Mice; Nuclear Pore; Phosphoproteins; Transcription Factors; Transcription, Genetic; YAP-Signaling Proteins
PubMed: 29107331
DOI: 10.1016/j.cell.2017.10.008 -
Nature Reviews. Molecular Cell Biology May 2022Efficient and regulated nucleocytoplasmic trafficking of macromolecules to the correct subcellular compartment is critical for proper functions of the eukaryotic cell.... (Review)
Review
Efficient and regulated nucleocytoplasmic trafficking of macromolecules to the correct subcellular compartment is critical for proper functions of the eukaryotic cell. The majority of the macromolecular traffic across the nuclear pores is mediated by the Karyopherin-β (or Kap) family of nuclear transport receptors. Work over more than two decades has shed considerable light on how the different Kap family members bring their respective cargoes into the nucleus or the cytoplasm in efficient and highly regulated manners. In this Review, we overview the main features and established functions of Kap family members, describe how Kaps recognize their cargoes and discuss the different ways in which these Kap-cargo interactions can be regulated, highlighting new findings and open questions. We also describe current knowledge of the import and export of the components of three large gene expression machines - the core replisome, RNA polymerase II and the ribosome - pointing out the questions that persist about how such large macromolecular complexes are trafficked to serve their function in a designated subcellular location.
Topics: Active Transport, Cell Nucleus; Cell Nucleus; Karyopherins; Nuclear Pore; Receptors, Cytoplasmic and Nuclear; beta Karyopherins
PubMed: 35058649
DOI: 10.1038/s41580-021-00446-7 -
Signal Transduction and Targeted Therapy Nov 2023Proper subcellular localization is crucial for the functioning of biomacromolecules, including proteins and RNAs. Nuclear transport is a fundamental cellular process... (Review)
Review
Proper subcellular localization is crucial for the functioning of biomacromolecules, including proteins and RNAs. Nuclear transport is a fundamental cellular process that regulates the localization of many macromolecules within the nuclear or cytoplasmic compartments. In humans, approximately 60 proteins are involved in nuclear transport, including nucleoporins that form membrane-embedded nuclear pore complexes, karyopherins that transport cargoes through these complexes, and Ran system proteins that ensure directed and rapid transport. Many of these nuclear transport proteins play additional and essential roles in mitosis, biomolecular condensation, and gene transcription. Dysregulation of nuclear transport is linked to major human diseases such as cancer, neurodegenerative diseases, and viral infections. Selinexor (KPT-330), an inhibitor targeting the nuclear export factor XPO1 (also known as CRM1), was approved in 2019 to treat two types of blood cancers, and dozens of clinical trials of are ongoing. This review summarizes approximately three decades of research data in this field but focuses on the structure and function of individual nuclear transport proteins from recent studies, providing a cutting-edge and holistic view on the role of nuclear transport proteins in health and disease. In-depth knowledge of this rapidly evolving field has the potential to bring new insights into fundamental biology, pathogenic mechanisms, and therapeutic approaches.
Topics: Humans; Receptors, Cytoplasmic and Nuclear; Active Transport, Cell Nucleus; Karyopherins; Nuclear Pore Complex Proteins; Neoplasms; ran GTP-Binding Protein
PubMed: 37945593
DOI: 10.1038/s41392-023-01649-4 -
Nature Cell Biology Jun 2022Mechanical force controls fundamental cellular processes in health and disease, and increasing evidence shows that the nucleus both experiences and senses applied...
Mechanical force controls fundamental cellular processes in health and disease, and increasing evidence shows that the nucleus both experiences and senses applied forces. Such forces can lead to the nuclear translocation of proteins, but whether force controls nucleocytoplasmic transport, and how, remains unknown. Here we show that nuclear forces differentially control passive and facilitated nucleocytoplasmic transport, setting the rules for the mechanosensitivity of shuttling proteins. We demonstrate that nuclear force increases permeability across nuclear pore complexes, with a dependence on molecular weight that is stronger for passive than for facilitated diffusion. Owing to this differential effect, force leads to the translocation of cargoes into or out of the nucleus within a given range of molecular weight and affinity for nuclear transport receptors. Further, we show that the mechanosensitivity of several transcriptional regulators can be both explained by this mechanism and engineered exogenously by introducing appropriate nuclear localization signals. Our work unveils a mechanism of mechanically induced signalling, probably operating in parallel with others, with potential applicability across signalling pathways.
Topics: Active Transport, Cell Nucleus; Cell Nucleus; Nuclear Pore; Protein Transport; Receptors, Cytoplasmic and Nuclear
PubMed: 35681009
DOI: 10.1038/s41556-022-00927-7 -
Biochimica Et Biophysica Acta Jan 2014Proteasomes are highly conserved multisubunit protease complexes and occur in the cyto- and nucleoplasm of eukaryotic cells. In dividing cells proteasomes exist as... (Review)
Review
Proteasomes are highly conserved multisubunit protease complexes and occur in the cyto- and nucleoplasm of eukaryotic cells. In dividing cells proteasomes exist as holoenzymes and primarily localize in the nucleus. During quiescence they dissociate into proteolytic core and regulatory complexes and are sequestered into motile cytosolic clusters. Proteasome clusters rapidly clear upon the exit from quiescence, where proteasome core and regulatory complexes reassemble and localize to the nucleus again. The mechanisms underlying proteasome transport and assembly are not yet understood. Here, I summarize our present knowledge about nuclear transport and assembly of proteasomes in yeast and project our studies in this eukaryotic model organism to the mammalian cell system. This article is part of a Special Issue entitled: Ubiquitin-Proteasome System. Guest Editors: Thomas Sommer and Dieter H. Wolf.
Topics: Active Transport, Cell Nucleus; Animals; Cell Division; Cell Nucleus; Genetic Variation; Humans; Kinetics; Models, Molecular; Proteasome Endopeptidase Complex
PubMed: 23545412
DOI: 10.1016/j.bbamcr.2013.03.023 -
International Journal of Molecular... May 2022The relationship between transcription and aging is one that has been studied intensively and experimentally with diverse attempts. However, the impact of the nuclear... (Review)
Review
The relationship between transcription and aging is one that has been studied intensively and experimentally with diverse attempts. However, the impact of the nuclear mRNA export on the aging process following its transcription is still poorly understood, although the nuclear events after transcription are coupled closely with the transcription pathway because the essential factors required for mRNA transport, namely TREX, TREX-2, and nuclear pore complex (NPC), physically and functionally interact with various transcription factors, including the activator/repressor and pre-mRNA processing factors. Dysregulation of the mediating factors for mRNA export from the nucleus generally leads to the aberrant accumulation of nuclear mRNA and further impairment in the vegetative growth and normal lifespan and the pathogenesis of neurodegenerative diseases. The optimal stoichiometry and density of NPC are destroyed during the process of cellular aging, and their damage triggers a defect of function in the nuclear permeability barrier. This review describes recent findings regarding the role of the nuclear mRNA export in cellular aging and age-related neurodegenerative disorders.
Topics: Active Transport, Cell Nucleus; Cell Nucleus; Nuclear Pore; RNA Transport; RNA, Messenger
PubMed: 35628261
DOI: 10.3390/ijms23105451 -
The Journal of Biological Chemistry Jul 2022The ubiquitin-proteasome system fulfills an essential role in regulating protein homeostasis by spatially and temporally controlling proteolysis in an ATP- and... (Review)
Review
The ubiquitin-proteasome system fulfills an essential role in regulating protein homeostasis by spatially and temporally controlling proteolysis in an ATP- and ubiquitin-dependent manner. However, the localization of proteasomes is highly variable under diverse cellular conditions. In yeast, newly synthesized proteasomes are primarily localized to the nucleus during cell proliferation. Yeast proteasomes are transported into the nucleus through the nuclear pore either as immature subcomplexes or as mature enzymes via adapter proteins Sts1 and Blm10, while in mammalian cells, postmitotic uptake of proteasomes into the nucleus is mediated by AKIRIN2, an adapter protein essentially required for nuclear protein degradation. Stressful growth conditions and the reversible halt of proliferation, that is quiescence, are associated with a decline in ATP and the reorganization of proteasome localization. Cellular stress leads to proteasome accumulation in membraneless granules either in the nucleus or in the cytoplasm. In quiescence, yeast proteasomes are sequestered in an ubiquitin-dependent manner into motile and reversible proteasome storage granules in the cytoplasm. In cancer cells, upon amino acid deprivation, heat shock, osmotic stress, oxidative stress, or the inhibition of either proteasome activity or nuclear export, reversible proteasome foci containing polyubiquitinated substrates are formed by liquid-liquid phase separation in the nucleus. In this review, we summarize recent literature revealing new links between nuclear transport, ubiquitin signaling, and the intracellular organization of proteasomes during cellular stress conditions.
Topics: Active Transport, Cell Nucleus; Adenosine Triphosphate; Animals; Cytoplasm; Mammals; Proteasome Endopeptidase Complex; Saccharomyces cerevisiae; Ubiquitin
PubMed: 35636514
DOI: 10.1016/j.jbc.2022.102083 -
The Journal of Biological Chemistry Mar 2019In eukaryotes, the separation of translation from transcription by the nuclear envelope enables mRNA modifications such as capping, splicing, and polyadenylation. These... (Review)
Review
In eukaryotes, the separation of translation from transcription by the nuclear envelope enables mRNA modifications such as capping, splicing, and polyadenylation. These modifications are mediated by a spectrum of ribonuclear proteins that associate with preRNA transcripts, coordinating the different steps and coupling them to nuclear export, ensuring that only mature transcripts reach the cytoplasmic translation machinery. Although the components of this machinery have been identified and considerable functional insight has been achieved, a number of questions remain outstanding about mRNA nuclear export and how it is integrated into the nuclear phase of the gene expression pathway. Nuclear export factors mediate mRNA transit through nuclear pores to the cytoplasm, after which these factors are removed from the mRNA, preventing transcripts from returning to the nucleus. However, as outlined in this review, several aspects of the mechanism by which transport factor binding and release are mediated remain unclear, as are the roles of accessory nuclear components in these processes. Moreover, the mechanisms by which completion of mRNA splicing and polyadenylation are recognized, together with how they are coordinated with nuclear export, also remain only partially characterized. One attractive hypothesis is that dissociating poly(A) polymerase from the cleavage and polyadenylation machinery could signal completion of mRNA maturation and thereby provide a mechanism for initiating nuclear export. The impressive array of genetic, molecular, cellular, and structural data that has been generated about these systems now provides many of the tools needed to define the precise mechanisms involved in these processes and how they are integrated.
Topics: Active Transport, Cell Nucleus; Animals; Cell Nucleus; Humans; Polyadenylation; RNA Splicing; RNA Transport; RNA, Messenger
PubMed: 30683695
DOI: 10.1074/jbc.REV118.005594 -
Neurotherapeutics : the Journal of the... Jul 2022The nuclear pore complex (NPC) is a large multimeric structure that is interspersed throughout the membrane of the nucleus and consists of at least 33 protein... (Review)
Review
The nuclear pore complex (NPC) is a large multimeric structure that is interspersed throughout the membrane of the nucleus and consists of at least 33 protein components. Individual components cooperate within the nuclear pore to facilitate selective passage of materials between the nucleus and cytoplasm while simultaneously performing pore-independent roles throughout the cell. NPC dysfunction is a hallmark of neurodegenerative disorders including Alzheimer's disease, Huntington's disease, and amyotrophic lateral sclerosis (ALS). NPC components can become mislocalized or altered in expression in neurodegeneration. These alterations in NPC structure are often detrimental to the neuronal function and ultimately lead to neuronal loss. This review highlights the importance of nucleocytoplasmic transport and NPC integrity and how dysfunction of such may contribute to neurodegeneration.
Topics: Humans; Nuclear Pore; Active Transport, Cell Nucleus; Amyotrophic Lateral Sclerosis; Cytoplasm; Cell Nucleus
PubMed: 36070178
DOI: 10.1007/s13311-022-01293-w -
Methods in Molecular Biology (Clifton,... 2022The process of eukaryotic ribosome assembly stretches across the nucleolus, the nucleoplasm and the cytoplasm, and therefore relies on efficient nucleocytoplasmic...
The process of eukaryotic ribosome assembly stretches across the nucleolus, the nucleoplasm and the cytoplasm, and therefore relies on efficient nucleocytoplasmic transport. In yeast, the import machinery delivers ~140,000 ribosomal proteins every minute to the nucleus for ribosome assembly. At the same time, the export machinery facilitates translocation of ~2000 pre-ribosomal particles every minute through ~200 nuclear pore complexes (NPC) into the cytoplasm. Eukaryotic ribosome assembly also requires >200 conserved assembly factors, which transiently associate with pre-ribosomal particles. Their site(s) of action on maturing pre-ribosomes are beginning to be elucidated. In this chapter, we outline protocols that enable rapid biochemical isolation of pre-ribosomal particles for single particle cryo-electron microscopy (cryo-EM) and in vitro reconstitution of nuclear transport processes. We discuss cell-biological and genetic approaches to investigate how the ribosome assembly and the nucleocytoplasmic transport machineries collaborate to produce functional ribosomes.
Topics: Active Transport, Cell Nucleus; Cryoelectron Microscopy; Ribosomal Proteins; Ribosomes; Saccharomyces cerevisiae; Saccharomyces cerevisiae Proteins
PubMed: 35796985
DOI: 10.1007/978-1-0716-2501-9_7