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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 -
Nature May 2023The approximately 120 MDa mammalian nuclear pore complex (NPC) acts as a gatekeeper for the transport between the nucleus and cytosol. The central channel of the NPC...
The approximately 120 MDa mammalian nuclear pore complex (NPC) acts as a gatekeeper for the transport between the nucleus and cytosol. The central channel of the NPC is filled with hundreds of intrinsically disordered proteins (IDPs) called FG-nucleoporins (FG-NUPs). Although the structure of the NPC scaffold has been resolved in remarkable detail, the actual transport machinery built up by FG-NUPs-about 50 MDa-is depicted as an approximately 60-nm hole in even highly resolved tomograms and/or structures computed with artificial intelligence. Here we directly probed conformations of the vital FG-NUP98 inside NPCs in live cells and in permeabilized cells with an intact transport machinery by using a synthetic biology-enabled site-specific small-molecule labelling approach paired with highly time-resolved fluorescence microscopy. Single permeabilized cell measurements of the distance distribution of FG-NUP98 segments combined with coarse-grained molecular simulations of the NPC allowed us to map the uncharted molecular environment inside the nanosized transport channel. We determined that the channel provides-in the terminology of the Flory polymer theory-a 'good solvent' environment. This enables the FG domain to adopt expanded conformations and thus control transport between the nucleus and cytoplasm. With more than 30% of the proteome being formed from IDPs, our study opens a window into resolving disorder-function relationships of IDPs in situ, which are important in various processes, such as cellular signalling, phase separation, ageing and viral entry.
Topics: Animals; Active Transport, Cell Nucleus; Artificial Intelligence; Cell Nucleus; Intrinsically Disordered Proteins; Nuclear Pore; Nuclear Pore Complex Proteins; Microscopy, Fluorescence
PubMed: 37100914
DOI: 10.1038/s41586-023-05990-0 -
Biochemical Society Transactions Dec 2020The transport of histones from the cytoplasm to the nucleus of the cell, through the nuclear membrane, is a cellular process that regulates the supply of new histones in... (Review)
Review
The transport of histones from the cytoplasm to the nucleus of the cell, through the nuclear membrane, is a cellular process that regulates the supply of new histones in the nucleus and is key for DNA replication and transcription. Nuclear import of histones is mediated by proteins of the karyopherin family of nuclear transport receptors. Karyopherins recognize their cargos through linear motifs known as nuclear localization/export sequences or through folded domains in the cargos. Karyopherins interact with nucleoporins, proteins that form the nuclear pore complex, to promote the translocation of their cargos into the nucleus. When binding to histones, karyopherins not only function as nuclear import receptors but also as chaperones, protecting histones from non-specific interactions in the cytoplasm, in the nuclear pore and possibly in the nucleus. Studies have also suggested that karyopherins might participate in histones deposition into nucleosomes. In this review we describe structural and biochemical studies from the last two decades on how karyopherins recognize and transport the core histone proteins H3, H4, H2A and H2B and the linker histone H1 from the cytoplasm to the nucleus, which karyopherin is the major nuclear import receptor for each of these histones, the oligomeric state of histones during nuclear import and the roles of post-translational modifications, histone-chaperones and RanGTP in regulating these nuclear import pathways.
Topics: Active Transport, Cell Nucleus; Cell Cycle Proteins; Cell Nucleus; Cytoplasm; GTP Phosphohydrolases; Histones; Humans; Karyopherins; Molecular Chaperones; Nuclear Proteins; Protein Conformation; Protein Processing, Post-Translational; Receptors, Cytoplasmic and Nuclear; Saccharomyces cerevisiae; Saccharomyces cerevisiae Proteins
PubMed: 33300986
DOI: 10.1042/BST20200572 -
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 -
Molecular Microbiology Oct 2022Parvoviruses are small non-enveloped single-stranded DNA viruses, which depend on host cell nuclear transcriptional and replication machinery. After endosomal exposure... (Review)
Review
Parvoviruses are small non-enveloped single-stranded DNA viruses, which depend on host cell nuclear transcriptional and replication machinery. After endosomal exposure of nuclear localization sequence and a phospholipase A domain on the capsid surface, and escape into the cytosol, parvovirus capsids enter the nucleus. Due to the small capsid diameter of 18-26 nm, intact capsids can potentially pass into the nucleus through nuclear pore complexes (NPCs). This might be facilitated by active nuclear import, but capsids may also follow an alternative entry pathway that includes activation of mitotic factors and local transient disruption of the nuclear envelope. The nuclear entry is followed by currently undefined events of viral genome uncoating. After genome release, viral replication compartments are initiated and infection proceeds. Parvoviral genomes replicate during cellular S phase followed by nuclear capsid assembly during virus-induced S/G2 cell cycle arrest. Nuclear egress of capsids occurs upon nuclear envelope degradation during apoptosis and cell lysis. An alternative pathway for nuclear export has been described using active transport through the NPC mediated by the chromosome region maintenance 1 protein, CRM1, which is enhanced by phosphorylation of the N-terminal domain of VP2. However, other alternative but not yet uncharacterized nuclear export pathways cannot be excluded.
Topics: DNA, Single-Stranded; Virus Replication; Parvovirus; Cell Nucleus; Active Transport, Cell Nucleus; Nuclear Pore; Nuclear Envelope; Capsid Proteins; Phospholipases
PubMed: 35974704
DOI: 10.1111/mmi.14974 -
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 -
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