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El-Tanani M, Nsairat H, Mishra V, Mishra Y, Aljabali AAA, Serrano-Aroca Á, Tambuwala MM. Ran GTPase and Its Importance in Cellular Signaling and Malignant Phenotype. Int J Mol Sci 2023; 24:ijms24043065. [PMID: 36834476 PMCID: PMC9968026 DOI: 10.3390/ijms24043065] [Citation(s) in RCA: 15] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2022] [Revised: 01/10/2023] [Accepted: 01/11/2023] [Indexed: 02/08/2023] Open
Abstract
Ran is a member of the Ras superfamily of proteins, which primarily regulates nucleocytoplasmic trafficking and mediates mitosis by regulating spindle formation and nuclear envelope (NE) reassembly. Therefore, Ran is an integral cell fate determinant. It has been demonstrated that aberrant Ran expression in cancer is a result of upstream dysregulation of the expression of various factors, such as osteopontin (OPN), and aberrant activation of various signaling pathways, including the extracellular-regulated kinase/mitogen-activated protein kinase (ERK/MEK) and phosphatidylinositol 3-kinase/Protein kinase B (PI3K/Akt) pathways. In vitro, Ran overexpression has severe effects on the cell phenotype, altering proliferation, adhesion, colony density, and invasion. Therefore, Ran overexpression has been identified in numerous types of cancer and has been shown to correlate with tumor grade and the degree of metastasis present in various cancers. The increased malignancy and invasiveness have been attributed to multiple mechanisms. Increased dependence on Ran for spindle formation and mitosis is a consequence of the upregulation of these pathways and the ensuing overexpression of Ran, which increases cellular dependence on Ran for survival. This increases the sensitivity of cells to changes in Ran concentration, with ablation being associated with aneuploidy, cell cycle arrest, and ultimately, cell death. It has also been demonstrated that Ran dysregulation influences nucleocytoplasmic transport, leading to transcription factor misallocation. Consequently, patients with tumors that overexpress Ran have been shown to have a higher malignancy rate and a shorter survival time compared to their counterparts.
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Affiliation(s)
- Mohamed El-Tanani
- Pharmacological and Diagnostic Research Centre, Faculty of Pharmacy, Al-Ahliyya Amman University, Amman 19328, Jordan
- Correspondence:
| | - Hamdi Nsairat
- Pharmacological and Diagnostic Research Centre, Faculty of Pharmacy, Al-Ahliyya Amman University, Amman 19328, Jordan
| | - Vijay Mishra
- School of Pharmaceutical Sciences, Lovely Professional University, Phagwara 144411, India
| | - Yachana Mishra
- Department of Zoology, School of Bioengineering and Biosciences, Lovely Professional University, Phagwara 144411, India
| | - Alaa A. A. Aljabali
- Department of Pharmaceutics & Pharmaceutical Technology, Yarmouk University, Irbid 21163, Jordan
| | - Ángel Serrano-Aroca
- Biomaterials and Bioengineering Laboratory, Centro de Investigación Traslacional San Alberto Magno, Universidad Católica de Valencia San Vicente Mártir, c/Guillem de Castro 94, 46001 Valencia, Spain
| | - Murtaza M. Tambuwala
- Lincoln Medical School, University of Lincoln, Brayford Pool, Lincoln LN6 7TS, UK
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Rodriguez CM, Todd PK. New pathologic mechanisms in nucleotide repeat expansion disorders. Neurobiol Dis 2019; 130:104515. [PMID: 31229686 DOI: 10.1016/j.nbd.2019.104515] [Citation(s) in RCA: 45] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2019] [Revised: 06/07/2019] [Accepted: 06/19/2019] [Indexed: 12/14/2022] Open
Abstract
Tandem microsatellite repeats are common throughout the human genome and intrinsically unstable, exhibiting expansions and contractions both somatically and across generations. Instability in a small subset of these repeats are currently linked to human disease, although recent findings suggest more disease-causing repeats await discovery. These nucleotide repeat expansion disorders (NREDs) primarily affect the nervous system and commonly lead to neurodegeneration through toxic protein gain-of-function, protein loss-of-function, and toxic RNA gain-of-function mechanisms. However, the lines between these categories have blurred with recent findings of unconventional Repeat Associated Non-AUG (RAN) translation from putatively non-coding regions of the genome. Here we review two emerging topics in NREDs: 1) The mechanisms by which RAN translation occurs and its role in disease pathogenesis and 2) How nucleotide repeats as RNA and translated proteins influence liquid-liquid phase separation, membraneless organelle dynamics, and nucleocytoplasmic transport. We examine these topics with a particular eye on two repeats: the CGG repeat expansion responsible for Fragile X syndrome and Fragile X-associated Tremor Ataxia Syndrome (FXTAS) and the intronic GGGGCC repeat expansion in C9orf72, the most common inherited cause of amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD). Our thesis is that these emerging disease mechanisms can inform a broader understanding of the native roles of microsatellites in cellular function and that aberrations in these native processes provide clues to novel therapeutic strategies for these currently untreatable disorders.
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Affiliation(s)
- C M Rodriguez
- Department of Neurology, University of Michigan, Ann Arbor, MI, USA; Department of Genetics, Stanford University, Stanford, CA, USA
| | - P K Todd
- Department of Neurology, University of Michigan, Ann Arbor, MI, USA; VA Ann Arbor Healthcare System, Ann Arbor, MI, USA.
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Evidence for an evolutionary relationship between the large adaptor nucleoporin Nup192 and karyopherins. Proc Natl Acad Sci U S A 2014; 111:2530-5. [PMID: 24505056 DOI: 10.1073/pnas.1311081111] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Nucleocytoplasmic transport is facilitated by nuclear pore complexes (NPCs), which are massive proteinaceous transport channels embedded in the nuclear envelope. Nup192 is a major component of an adaptor nucleoporin subcomplex proposed to link the NPC coat with the central transport channel. Here, we present the structure of the ∼110-kDa N-terminal domain (NTD) of Nup192 at 2.7-Å resolution. The structure reveals an open ring-shaped architecture composed of Huntingtin, EF3, PP2A, and TOR1 (HEAT) and Armadillo (ARM) repeats. A comparison of different conformations indicates that the NTD consists of two rigid halves connected by a flexible hinge. Unexpectedly, the two halves of the ring are structurally related to karyopherin-α (Kap-α) and β-karyopherin family members. Biochemically, we identify a conserved patch that binds an unstructured segment in Nup53 and show that a C-terminal tail region binds to a putative helical fragment in Nic96. The Nup53 segment that binds Nup192 is a classical nuclear localization-like sequence that interacts with Kap-α in a mutually exclusive and mechanistically distinct manner. The disruption of the Nup53 and Nic96 binding sites in vivo yields growth and mRNA export defects, revealing their critical role in proper NPC function. Surprisingly, both interactions are dispensable for NPC localization, suggesting that Nup192 possesses another nucleoporin interaction partner. These data indicate that the structured domains in the adaptor nucleoporin complex are held together by peptide interactions that resemble those found in karyopherin•cargo complexes and support the proposal that the adaptor nucleoporins arose from ancestral karyopherins.
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Stuwe T, von Borzyskowski LS, Davenport AM, Hoelz A. Molecular basis for the anchoring of proto-oncoprotein Nup98 to the cytoplasmic face of the nuclear pore complex. J Mol Biol 2012; 419:330-46. [PMID: 22480613 DOI: 10.1016/j.jmb.2012.03.024] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2012] [Revised: 03/22/2012] [Accepted: 03/26/2012] [Indexed: 01/09/2023]
Abstract
The cytoplasmic filament nucleoporins of the nuclear pore complex (NPC) are critically involved in nuclear export and remodeling of mRNA ribonucleoprotein particles and are associated with various human malignancies. Here, we report the crystal structure of the Nup98 C-terminal autoproteolytic domain, frequently missing from leukemogenic forms of the protein, in complex with the N-terminal domain of Nup82 and the C-terminal tail fragment of Nup159. The Nup82 β propeller serves as a noncooperative binding platform for both binding partners. Interaction of Nup98 with Nup82 occurs through a reciprocal exchange of loop structures. Strikingly, the same Nup98 groove promiscuously interacts with Nup82 and Nup96 in a mutually excusive fashion. Simultaneous disruption of both Nup82 interactions in yeast causes severe defects in mRNA export, while the severing of a single interaction is tolerated. Thus, the cytoplasmic filament network of the NPC is robust, consistent with its essential function in nucleocytoplasmic transport.
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Affiliation(s)
- Tobias Stuwe
- California Institute of Technology, Division of Chemistry and Chemical Engineering, 1200 East California Boulevard, Pasadena, CA 91125, USA
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Abstract
In eukaryotic cells, the spatial segregation of replication and transcription in the nucleus and translation in the cytoplasm imposes the requirement of transporting thousands of macromolecules between these two compartments. Nuclear pore complexes (NPCs) are the sole gateways that facilitate this macromolecular exchange across the nuclear envelope with the help of soluble transport receptors. Whereas the mobile transport machinery is reasonably well understood at the atomic level, a commensurate structural characterization of the NPC has only begun in the past few years. Here, we describe the recent progress toward the elucidation of the atomic structure of the NPC, highlight emerging concepts of its underlying architecture, and discuss key outstanding questions and challenges. The applied structure determination as well as the described design principles of the NPC may serve as paradigms for other macromolecular assemblies.
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Affiliation(s)
- André Hoelz
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, USA.
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Debler EW, Hsia KC, Nagy V, Seo HS, Hoelz A. Characterization of the membrane-coating Nup84 complex. Nucleus 2010. [DOI: 10.4161/nucl.11120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
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Nakano H, Funasaka T, Hashizume C, Wong RW. Nucleoporin translocated promoter region (Tpr) associates with dynein complex, preventing chromosome lagging formation during mitosis. J Biol Chem 2010; 285:10841-9. [PMID: 20133940 DOI: 10.1074/jbc.m110.105890] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Gain or loss of whole chromosomes is often observed in cancer cells and is thought to be due to aberrant chromosome segregation during mitosis. Proper chromosome segregation depends on a faithful interaction between spindle microtubules and kinetochores. Several components of the nuclear pore complex/nucleoporins play critical roles in orchestrating the rapid remodeling events that occur during mitosis. Our recent studies revealed that the nucleoporin, Rae1, plays critical roles in maintaining spindle bipolarity. Here, we show association of another nucleoporin, termed Tpr (translocated promoter region), with the molecular motors dynein and dynactin, which both orchestrate with the spindle checkpoints Mad1 and Mad2 during cell division. Overexpression of Tpr enhanced multinucleated cell formation. RNA interference-mediated knockdown of Tpr caused a severe lagging chromosome phenotype and disrupted spindle checkpoint proteins expression and localization. Next, we performed a series of rescue and dominant negative experiments to confirm that Tpr orchestrates proper chromosome segregation through interaction with dynein light chain. Our data indicate that Tpr functions as a spatial and temporal regulator of spindle checkpoints, ensuring the efficient recruitment of checkpoint proteins to the molecular motor dynein to promote proper anaphase formation.
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Affiliation(s)
- Hiroshi Nakano
- Frontier Science Organization and Cancer Research Institute, Kanazawa University, Kakuma-machi, Kanazawa, Ishikawa 920-1192, Japan
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Debler EW, Hsia KC, Nagy V, Seo HS, Hoelz A. Characterization of the membrane-coating Nup84 complex: paradigm for the nuclear pore complex structure. Nucleus 2010; 1:150-7. [PMID: 21326946 DOI: 10.4161/nucl.1.2.11120] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2010] [Accepted: 01/03/2010] [Indexed: 11/19/2022] Open
Abstract
Nuclear pore complexes (NPCs) function as selective gates for nucleocytoplasmic transport. Although the NPC was discovered more than half a century ago, our knowledge of NPC components in atomic detail has exploded only over the past few years. Recent structural, biochemical, and in vivo studies of NPC components, in particular the membrane-coating heptameric Nup84 complex, have shed light onto the NPC architecture as well as onto its dynamic nature. Striking similarities were revealed between the components of the NPC and of coat protein complexes in the endocytic and secretory pathways, supporting their common evolutionary origin in a progenitor protocoatomer. Here, we summarize these findings and discuss emerging concepts that underlie the molecular architecture and the dynamics of the NPC. We conclude that the uncovered principles are not limited to the NPC, but are likely to extend to other macromolecular assemblies.
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Affiliation(s)
- Erik W Debler
- Laboratory of Cell Biology, The Rockefeller University, New York, NY, USA
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Structure of a trimeric nucleoporin complex reveals alternate oligomerization states. Proc Natl Acad Sci U S A 2009; 106:17693-8. [PMID: 19805193 DOI: 10.1073/pnas.0909373106] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
The heptameric Nup84 complex constitutes an evolutionarily conserved building block of the nuclear pore complex. Here, we present the crystal structure of the heterotrimeric Sec13 x Nup145C x Nup84 complex, the centerpiece of the heptamer, at 3.2-A resolution. Nup84 forms a U-shaped alpha-helical solenoid domain, topologically similar to two other members of the heptamer, Nup145C and Nup85. The interaction between Nup84 and Nup145C is mediated via a hydrophobic interface located in the kink regions of the two solenoids that is reinforced by additional interactions of two long Nup84 loops. The Nup84 binding site partially overlaps with the homo-dimerization interface of Nup145C, suggesting competing binding events. Fitting of the elongated Z-shaped heterotrimer into electron microscopy (EM) envelopes of the heptamer indicates that structural changes occur at the Nup145C x Nup84 interface. Docking the crystal structures of all heptamer components into the EM envelope constitutes a major advance toward the completion of the structural characterization of the Nup84 complex.
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