GO:1990876 cytoplasmic side of nuclear pore: Components, Assembly and Research Methods, Genes, Functions and Research Methods
Research-grade guide for scientists and biopharma professionals
Key Takeaways
• GO:1990876 defines the cytoplasmic side of the nuclear pore complex (NPC), the face of the NPC that is exposed to the cytoplasm and serves as the entry gate for nuclear import and the exit platform for mRNA export.
• The cytoplasmic side is enriched in nucleoporins such as NUP358 (RANBP2), NUP214, NUP88, NUP62, NUP98, and the NUP107-160 complex, which form the cytoplasmic ring and filaments.
• The small GTPase Ran and its regulators establish the directionality of nucleocytoplasmic transport across the NPC, with the cytoplasmic side being the site of cargo release and RanGAP-mediated GTP hydrolysis.
• The cytoplasmic side of the NPC is a hub for mRNA export surveillance and quality control, involving the TREX-2 complex and the mRNA export platform.
• Dysfunction of cytoplasmic NPC components is linked to cancer, neurodegenerative diseases, and viral infections, including hepatitis B virus entry via the NPC-associated receptor SCARF2.
• CRISPR-based knockout, point mutation, knock-in, and overexpression models are essential to dissect the function of cytoplasmic nucleoporins and their role in disease.
Description
The nuclear pore complex (NPC) is a large proteinaceous channel that spans the nuclear envelope and mediates all nucleocytoplasmic trafficking. The NPC is structurally and functionally asymmetric, with distinct cytoplasmic and nuclear faces. The cytoplasmic side of the nuclear pore (GO:1990876) is the face of the NPC that is exposed to the cytoplasm and is the first point of contact for nuclear import cargoes and the last for nuclear export cargoes. This subcompartment is defined by specific nucleoporins and accessory factors that form the cytoplasmic ring and filaments, which are critical for cargo recognition, transport directionality, and mRNA export quality control. Understanding the cytoplasmic side of the NPC is essential for researchers studying nucleocytoplasmic transport, gene expression regulation, and diseases linked to NPC dysfunction. Recent structural and functional studies have revealed the molecular architecture of the cytoplasmic ring and its dynamic regulation by Ran GTPase and other factors. This article provides a comprehensive overview of GO:1990876, covering its definition, structure, molecular mechanisms, associated genes, disease relevance, and research methods, with a focus on CRISPR-based approaches for functional interrogation.
cytoplasmic side of nuclear pore At A Glance
| GO ID | GO:1990876 |
|---|---|
| GO term | cytoplasmic side of nuclear pore |
| Ontology | cellular_component |
| Synonym | cytoplasmic side of NPC; cytoplasmic side of nuclear pore complex; cytoplasmic side of nucleopore |
| Major function | Entry site for nuclear import, exit platform for mRNA export, and hub for transport regulation and quality control |
| Key components | NUP358 (RANBP2), NUP214, NUP88, NUP62, NUP98, NUP107-160 complex, NUP153, RanGAP, TREX-2 |
| Related processes | Nucleocytoplasmic transport, mRNA export, NPC assembly and disassembly, viral entry |
| Disease relevance | Cancer, neurodegenerative diseases, viral infections, and developmental disorders |
What Is GO:1990876?
GO:1990876, cytoplasmic side of nuclear pore, is a cellular component term that refers to the side of the nuclear pore complex (NPC) that faces the cytoplasm [QuickGO]. It is synonymous with the cytoplasmic side of the NPC, the cytoplasmic side of the nuclear pore complex, and the cytoplasmic side of the nucleopore. This subcompartment includes the cytoplasmic ring, cytoplasmic filaments, and associated proteins that are oriented toward the cytoplasm, distinguishing it from the nuclear side of the NPC.
Why Is cytoplasmic side of nuclear pore Important in Cell Biology?
The cytoplasmic side of the nuclear pore is a critical interface for cellular communication between the nucleus and cytoplasm. It governs the selective import of nuclear proteins and the export of mRNAs and ribosomal subunits, thereby influencing gene expression, cell cycle progression, and stress responses. Dysregulation of this compartment is implicated in a wide range of human diseases, including cancer, neurodegeneration, and viral pathogenesis. Moreover, the cytoplasmic side is a target for viral entry and a platform for mRNA quality control, making it a focal point for therapeutic intervention and basic research.
• Controls nuclear import of transcription factors and signaling molecules, impacting gene expression.
• Serves as the primary site for mRNA export and quality control, linking transcription to translation.
• Regulates cell cycle progression by controlling the transport of cell cycle regulators.
• Is exploited by viruses such as hepatitis B virus for cellular entry via SCARF2.
• Mutations in nucleoporins cause tissue-specific diseases, including cancers and neuropathies.
• Provides a platform for RanGAP-mediated GTP hydrolysis, essential for transport directionality.
• Participates in NPC assembly and disassembly during mitosis, affecting genome stability.
• Is a hub for signaling pathways, including SUMOylation and phosphorylation.
• Offers targets for antiviral and anticancer therapies.
• Enables single-molecule imaging of transport dynamics in live cells.
Core Biology of GO:1990876
What Happens During cytoplasmic side of nuclear pore?
In simple terms: The cytoplasmic side of the nuclear pore is like the front door of the nucleus, where molecules enter and exit.
The cytoplasmic side of the nuclear pore is the initial docking site for nuclear import receptors carrying cargo proteins. Importin-beta family receptors bind to phenylalanine-glycine (FG) repeat nucleoporins on the cytoplasmic filaments, facilitating cargo translocation into the central channel. For nuclear export, the cytoplasmic side is the final destination where export complexes are disassembled upon RanGTP hydrolysis, releasing cargo into the cytoplasm. Additionally, the cytoplasmic side is where mRNA export complexes are remodeled and quality-checked before release.
Structural Assembly of the Cytoplasmic Ring
In simple terms: The cytoplasmic ring is a scaffold made of many proteins that forms the outer part of the nuclear pore.
The cytoplasmic ring of the NPC is composed of multiple copies of nucleoporins, including the NUP107-160 complex, NUP358 (RANBP2), NUP214, NUP88, and NUP98. Recent integrative cryo-EM and AlphaFold studies have revealed the molecular architecture of the cytoplasmic ring, showing how these proteins assemble into a stable yet dynamic structure. The cytoplasmic filaments, which extend from the ring into the cytoplasm, are formed by NUP358 and NUP214 and serve as docking sites for transport receptors.
Molecular Mechanism of Transport Across the Cytoplasmic Side
In simple terms: Transport through the pore is directed by a gradient of the Ran protein, which acts like a switch.
The small GTPase Ran defines the asymmetry of the NPC by maintaining a high concentration of RanGTP in the nucleus and RanGDP in the cytoplasm. On the cytoplasmic side, RanGAP (Ran GTPase-activating protein) is anchored to NUP358 and stimulates GTP hydrolysis, converting RanGTP to RanGDP. This hydrolysis triggers the disassembly of export complexes, releasing cargo into the cytoplasm. Conversely, import complexes are stable in the cytoplasm and only dissociate upon binding to RanGTP in the nucleus.
mRNA Export Platform and Quality Control
In simple terms: The cytoplasmic side acts as a checkpoint to ensure only correctly processed mRNAs leave the nucleus.
The cytoplasmic side of the NPC is a platform for mRNA export and surveillance. The TREX-2 complex, which associates with the NPC, couples transcription to mRNA export. The cytoplasmic mRNA export platform, including NUP358 and NUP214, interacts with export factors such as NXF1 and GLE1 to facilitate the release of messenger ribonucleoproteins (mRNPs). Defects in this platform lead to mRNA export defects and are linked to diseases.
Regulation of Cytoplasmic NPC Function
In simple terms: The activity of the cytoplasmic side is controlled by modifications and interacting proteins.
The cytoplasmic side of the NPC is regulated by post-translational modifications, including phosphorylation and SUMOylation, which affect nucleoporin interactions and transport efficiency. RanGAP and RanBP1 are key regulators that localize to the cytoplasmic filaments and modulate RanGTP hydrolysis. Additionally, the ESCRT machinery has been implicated in NPC sealing and quality control at the cytoplasmic side.
Key Genes Involved in GO:1990876 cytoplasmic side of nuclear pore
The following genes encode proteins that localize to or function at the cytoplasmic side of the nuclear pore, as supported by structural and functional studies.
| Gene | Major Role | Research Relevance |
|---|---|---|
| NUP358 (RANBP2) | Cytoplasmic filament component; docking site for import receptors; RanGAP anchor | Mutations cause autosomal dominant acute necrotizing encephalopathy; target for antiviral research |
| NUP214 | Cytoplasmic filament component; mRNA export platform | Involved in leukemogenesis; interacts with DEK-CAN fusion |
| NUP88 | Cytoplasmic ring component; interacts with NUP214 | Overexpressed in cancers; marker for poor prognosis |
| NUP62 | Central channel nucleoporin; FG repeats | Autoantigen in primary biliary cirrhosis; role in transport |
| NUP98 | Cytoplasmic and nuclear side; FG repeats | Fusion proteins in leukemia; regulates gene expression |
| NUP107 | NUP107-160 complex; cytoplasmic ring scaffold | Mutations cause nephrotic syndrome; essential for NPC assembly |
| NUP160 | NUP107-160 complex; cytoplasmic ring | Required for NPC assembly and mRNA export |
| NUP133 | NUP107-160 complex; cytoplasmic ring | Mutations linked to developmental disorders |
| NUP85 | NUP107-160 complex; cytoplasmic ring | Involved in NPC assembly and cell cycle |
| NUP96 | NUP107-160 complex; cytoplasmic ring | Role in interferon signaling and antiviral response |
| NUP153 | Nuclear side; but interacts with cytoplasmic components | Regulates NPC assembly and transport |
| RanGAP1 | Ran GTPase-activating protein; anchored at cytoplasmic filaments | Essential for nuclear transport directionality |
| RanBP1 | Ran-binding protein; cofactor for RanGAP | Regulates RanGTP hydrolysis |
| NXF1 (TAP) | mRNA export receptor; interacts with cytoplasmic NPC | Target for antiviral and cancer research |
| GLE1 | mRNA export factor; interacts with NUP214 | Mutations cause lethal congenital contracture syndrome |
| TREX-2 (GANP) | Couples transcription to mRNA export; associates with NPC | Role in gene expression regulation |
| SCARF2 | Intracellular receptor for hepatitis B virus; interacts with NPC | Mediates HBV entry; potential antiviral target |
| ESCRT-III | Membrane sealing; NPC quality control | Role in nuclear envelope reformation |
How Is cytoplasmic side of nuclear pore Regulated?
The cytoplasmic side of the nuclear pore is regulated by the Ran GTPase cycle, which establishes a gradient of RanGTP across the nuclear envelope. RanGAP1, anchored at the cytoplasmic filaments via NUP358, catalyzes GTP hydrolysis to maintain low cytoplasmic RanGTP levels. Phosphorylation of nucleoporins by kinases such as CDK1 and ERK regulates NPC disassembly and reassembly during mitosis. SUMOylation of NUP358 and other components modulates their interactions and transport functions. Additionally, the ESCRT machinery contributes to NPC sealing and quality control at the cytoplasmic side.
cytoplasmic side of nuclear pore and Human Disease
| Gene | Disease / Biology | Potential Experimental Model |
|---|---|---|
| NUP358 (RANBP2) | Acute necrotizing encephalopathy | Knock-in mouse model with patient mutations; KO cell lines |
| NUP214 | Leukemia | Knockout and overexpression in hematopoietic cells |
| NUP98 | Leukemia | CRISPR knock-in of fusion genes in cell lines |
| NUP107 | Nephrotic syndrome | Patient-derived iPSCs with point mutations |
| SCARF2 | Hepatitis B virus infection | KO hepatoma cells; overexpression for viral entry assays |
Cancer
Alterations in cytoplasmic nucleoporins are frequently observed in cancers. NUP88 is overexpressed in various malignancies and correlates with poor prognosis. NUP214 and NUP98 are involved in chromosomal translocations that produce oncogenic fusion proteins in leukemia. Dysregulation of mRNA export at the cytoplasmic side can lead to aberrant gene expression that promotes tumorigenesis.
Neurodegenerative and Developmental Disorders
Mutations in NUP358 (RANBP2) cause autosomal dominant acute necrotizing encephalopathy, a severe neurological disorder. Mutations in NUP107-160 complex components are linked to nephrotic syndrome and developmental abnormalities. Defects in NPC function contribute to aging and neurodegeneration by disrupting nucleocytoplasmic transport.
Viral Infections
The cytoplasmic side of the NPC is exploited by viruses for entry and replication. Hepatitis B virus uses SCARF2 as an intracellular receptor that interacts with the NPC to facilitate infection. Other viruses, such as HIV and herpesviruses, dock at the cytoplasmic filaments to deliver their genomes into the nucleus. Targeting these interactions is a promising antiviral strategy.
From cytoplasmic side of nuclear pore-Related Genes to Experimental Models
| Research Question | Suitable Model |
|---|---|
| What is the role of NUP358 in nuclear import? | Knockout cell lines (e.g., HEK293T) via CRISPR |
| How do point mutations in NUP214 affect mRNA export? | Point mutation knock-in cell lines |
| Can we visualize NPC dynamics in live cells? | Tagged knock-in of NUP107 with fluorescent protein |
| Does overexpression of NUP88 promote cancer? | Overexpression cell models and xenografts |
| What is the function of SCARF2 in HBV entry? | Knockout and overexpression in hepatocytes |
| How does RanGAP1 regulate transport directionality? | Knockout and rescue with mutant RanGAP1 |
How to Study the cytoplasmic side of nuclear pore Process
| Method | What It Measures | Typical Application |
|---|---|---|
| Cryo-EM | 3D structure of NPC subcomplexes | Determining cytoplasmic ring architecture |
| AlphaFold | Predicted protein structures | Modeling nucleoporin interactions |
| Proximity labeling (BioID) | Protein-protein interactions in living cells | Mapping the cytoplasmic NPC interactome |
| Live-cell imaging | Dynamic localization and transport | Visualizing mRNA export and import |
| CRISPR knockout screens | Gene essentiality and transport defects | Identifying novel NPC regulators |
| RNA-seq | Transcriptional changes upon NPC perturbation | Assessing gene expression upon nucleoporin KO |
| Immunoprecipitation-MS | Protein complex composition | Isolating cytoplasmic NPC complexes |
| Single-molecule tracking | Transport kinetics and diffusion | Measuring cargo dwell time at the NPC |
Structural Biology (Cryo-EM and AlphaFold)
Integrative cryo-EM combined with AlphaFold predictions has resolved the structure of the cytoplasmic ring of the NPC at near-atomic resolution. These methods reveal the arrangement of nucleoporins and their interactions, providing a framework for understanding transport mechanisms.
Proteomics and Interactomics
Proximity labeling and affinity purification mass spectrometry have identified the protein composition of the cytoplasmic side of the NPC, including transient interactors such as transport receptors and mRNA export factors. These approaches uncover dynamic changes in NPC composition under different conditions.
Live-Cell Imaging
Fluorescence microscopy of tagged nucleoporins allows real-time visualization of NPC assembly, cargo transport, and mRNA export at the cytoplasmic side. Single-molecule tracking provides kinetic parameters of transport.
Functional Genomics (RNAi and CRISPR Screens)
Genome-wide CRISPR knockout screens have identified nucleoporins required for nuclear transport and cell viability. These screens can be adapted to study viral entry and drug resistance.
How CRISPR Can Be Used to Study GO:1990876 cytoplasmic side of nuclear pore
Knockout
CRISPR knockout of cytoplasmic nucleoporins such as NUP358, NUP214, or NUP107 in cell lines abolishes specific transport pathways and reveals their essential functions. Knockout models are used to study mRNA export defects, cell cycle arrest, and viral resistance.
Point Mutation
Point mutations in nucleoporin genes, such as those found in patients with NUP358-associated encephalopathy, can be introduced via CRISPR to study disease mechanisms. These models help dissect the contribution of specific residues to transport and NPC assembly.
Knock-in
Knock-in of fluorescent tags (e.g., GFP) into endogenous nucleoporin loci enables live-cell imaging of the cytoplasmic side of the NPC. Knock-in of disease-associated fusion genes, such as NUP98-NSD1, models leukemia.
Overexpression
Overexpression of nucleoporins like NUP88 or NUP214 using CRISPR activation or lentiviral vectors mimics their upregulation in cancers and allows study of oncogenic mechanisms. Overexpression of SCARF2 enhances hepatitis B virus entry in hepatoma cells.
How EDITGENE Supports cytoplasmic side of nuclear pore Research
Researchers studying cytoplasmic side of nuclear pore-related genes often need to determine whether a candidate gene is causally involved in transport, disease, or viral entry. EDITGENE provides a comprehensive suite of CRISPR-based services to generate precisely engineered cell models, enabling functional validation and drug discovery.
Contact EDITGENE today to design your custom CRISPR model for cytoplasmic side of nuclear pore research.
Frequently Asked Questions About cytoplasmic side of nuclear pore
What is the cytoplasmic side of the nuclear pore?
The cytoplasmic side of the nuclear pore (GO:1990876) is the face of the nuclear pore complex that is exposed to the cytoplasm, serving as the entry site for nuclear import and the exit platform for mRNA export.
What genes are involved in the cytoplasmic side of the nuclear pore?
Key genes include NUP358 (RANBP2), NUP214, NUP88, NUP62, NUP98, NUP107, NUP160, RanGAP1, and NXF1, among others.
What is the function of the cytoplasmic side of the nuclear pore?
It mediates the docking and translocation of nuclear import cargoes, the release of export cargoes, and the quality control of mRNA export.
How is the cytoplasmic side of the nuclear pore regulated?
It is regulated by the Ran GTPase cycle, phosphorylation, SUMOylation, and interactions with RanGAP1 and ESCRT proteins.
What diseases are associated with the cytoplasmic side of the nuclear pore?
Mutations in nucleoporins are linked to cancer, acute necrotizing encephalopathy, nephrotic syndrome, and viral infections such as hepatitis B.
How can I study the cytoplasmic side of the nuclear pore using CRISPR?
CRISPR knockout, point mutation knock-in, tagged knock-in, and overexpression models allow functional dissection of nucleoporins and their role in transport and disease.
What is the structure of the cytoplasmic ring of the nuclear pore?
The cytoplasmic ring is composed of the NUP107-160 complex, NUP358, NUP214, and NUP88, forming a scaffold with filaments that extend into the cytoplasm.
Which viruses target the cytoplasmic side of the nuclear pore?
Hepatitis B virus uses SCARF2 to interact with the NPC, while other viruses dock at cytoplasmic filaments to deliver their genomes.
What methods are used to study the cytoplasmic side of the nuclear pore?
Cryo-EM, AlphaFold, proximity labeling, live-cell imaging, and CRISPR screens are commonly used.
Why is the cytoplasmic side of the nuclear pore important for cancer?
Dysregulation of nucleoporins such as NUP88 and NUP214 leads to aberrant transport and gene expression that promotes tumorigenesis.
Conclusion
The cytoplasmic side of the nuclear pore (GO:1990876) is a dynamic and essential subcompartment of the NPC that governs nuclear import, mRNA export, and cellular responses to stress and infection. Its molecular architecture and regulatory mechanisms have been illuminated by recent structural and functional studies. Dysfunction of this compartment is implicated in cancer, neurodegeneration, and viral pathogenesis, making it a compelling target for therapeutic development. CRISPR-based models are indispensable for dissecting the roles of individual nucleoporins and for identifying new drug targets. EDITGENE provides end-to-end CRISPR services to accelerate research on the cytoplasmic side of the nuclear pore.
References
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