scholarly journals In Pursuit of Distinctiveness: Transmembrane Nucleoporins and Their Disease Associations

2021 ◽  
Vol 11 ◽  
Author(s):  
Divya Bindra ◽  
Ram Kumar Mishra
Keyword(s):  
Nuclear Membrane ◽  
Cell Cycle Control ◽  
Strong Association ◽  
Nuclear Pore ◽  
Cellular Functions ◽  
Cellular Processes ◽  
Damage Repair ◽  
Disease Associations ◽  
Multiple Copies ◽  
Underlying Mechanisms

The bi-directional nucleocytoplasmic shuttling of macromolecules like molecular signals, transcription factors, regulatory proteins, and RNAs occurs exclusively through Nuclear Pore Complex (NPC) residing in the nuclear membrane. This magnanimous complex is essentially a congregation of ~32 conserved proteins termed Nucleoporins (Nups) present in multiple copies and mostly arranged as subcomplexes to constitute a functional NPC. Nups participate in ancillary functions such as chromatin organization, transcription regulation, DNA damage repair, genome stabilization, and cell cycle control, apart from their central role as nucleocytoplasmic conduits. Thus, Nups exert a role in the maintenance of cellular homeostasis. In mammals, precisely three nucleoporins traverse the nuclear membrane, are called transmembrane Nups (TM-Nups), and are involved in multiple cellular functions. Owing to their vital roles in cellular processes and homeostasis, dysregulation of nucleoporin function is implicated in various diseases. The deregulated functioning of TM-Nups can thus act as an opportune window for the development of diseases. Indeed, mounting evidence exhibits a strong association of TM-Nups in cancer and numerous other physiological disorders. These findings have provided much-needed insights into the novel mechanisms of disease progression. While nucleoporin’s functions have often been summarized in the disease context, a focus on TM-Nups has always lacked. This review emphasizes the elucidation of distinct canonical and non-canonical functions of mammalian TM-Nups and the underlying mechanisms of their disease association.

The diverse roles of the Nup93/Nic96 complex proteins – structural scaffolds of the nuclear pore complex with additional cellular functions

2014 ◽  
Vol 395 (5) ◽  
pp. 515-528 ◽  
Author(s):  
Benjamin Vollmer ◽  
Wolfram Antonin
Keyword(s):  
Nuclear Pore Complex ◽  
Nuclear Membrane ◽  
Building Blocks ◽  
Transport Processes ◽  
Nuclear Pore ◽  
Nuclear Pore Complexes ◽  
Cellular Functions ◽  
Complex Assembly ◽  
Essential Function ◽  
Pore Complexes

Abstract Nuclear pore complexes mediate the transport between the cell nucleoplasm and cytoplasm. These 125 MDa structures are among the largest assemblies found in eukaryotes, built from proteins organized in distinct subcomplexes that act as building blocks during nuclear pore complex biogenesis. In this review, we focus on one of these subcomplexes, the Nup93 complex in metazoa and its yeast counterpart, the Nic96 complex. We discuss its essential function in nuclear pore complex assembly as a linker between the nuclear membrane and the central part of the pore and its various roles in nuclear transport processes and beyond.

scholarly journals Ubiquitin-Specific Proteases: Players in Cancer Cellular Processes

2021 ◽  
Vol 14 (9) ◽  
pp. 848
Author(s):  
Lucas Cruz ◽  
Paula Soares ◽  
Marcelo Correia
Keyword(s):  
Protein Function ◽  
Deubiquitinating Enzymes ◽  
Post Translational Modification ◽  
Cellular Functions ◽  
Cellular Targets ◽  
Cellular Processes ◽  
Protein Ubiquitination ◽  
Damage Repair ◽  
Ubiquitin Molecule

Ubiquitination represents a post-translational modification (PTM) essential for the maintenance of cellular homeostasis. Ubiquitination is involved in the regulation of protein function, localization and turnover through the attachment of a ubiquitin molecule(s) to a target protein. Ubiquitination can be reversed through the action of deubiquitinating enzymes (DUBs). The DUB enzymes have the ability to remove the mono- or poly-ubiquitination signals and are involved in the maturation, recycling, editing and rearrangement of ubiquitin(s). Ubiquitin-specific proteases (USPs) are the biggest family of DUBs, responsible for numerous cellular functions through interactions with different cellular targets. Over the past few years, several studies have focused on the role of USPs in carcinogenesis, which has led to an increasing development of therapies based on USP inhibitors. In this review, we intend to describe different cellular functions, such as the cell cycle, DNA damage repair, chromatin remodeling and several signaling pathways, in which USPs are involved in the development or progression of cancer. In addition, we describe existing therapies that target the inhibition of USPs.

scholarly journals Nucleoporin Gene Fusions and Hematopoietic Malignancies

2014 ◽  
Vol 2014 ◽  
pp. 1-18 ◽  
Author(s):  
Birthe Fahrenkrog
Keyword(s):  
Molecular Mechanisms ◽  
Gene Expression Regulation ◽  
Cell Cycle Control ◽  
Nucleocytoplasmic Transport ◽  
Nuclear Pore ◽  
Nuclear Pore Complexes ◽  
Cellular Processes ◽  
Macromolecular Trafficking ◽  
Pore Complexes ◽  
Cellular Compartments

Nuclear pore complexes (NPCs) are the sole gateways between the nucleus and the cytoplasm of eukaryotic cells and they mediate all macromolecular trafficking between these cellular compartments. Nucleocytoplasmic transport is highly selective and precisely regulated and as such an important aspect of normal cellular function. Defects in this process or in its machinery have been linked to various human diseases, including cancer. Nucleoporins, which are about 30 proteins that built up NPCs, are critical players in nucleocytoplasmic transport and have also been shown to be key players in numerous other cellular processes, such as cell cycle control and gene expression regulation. This review will focus on the three nucleoporins Nup98, Nup214, and Nup358. Common to them is their significance in nucleocytoplasmic transport, their multiple other functions, and being targets for chromosomal translocations that lead to haematopoietic malignancies, in particular acute myeloid leukaemia. The underlying molecular mechanisms of nucleoporin-associated leukaemias are only poorly understood but share some characteristics and are distinguished by their poor prognosis and therapy outcome.

scholarly journals Loss and gain of function experiments implicate TMEM18 as a mediator of the strong association between genetic variants at human Chromosome 2p25.3 and obesity

2017 ◽  
Author(s):  
Rachel Larder ◽  
M. F. Michelle Sim ◽  
Pawan Gulati ◽  
Robin Antrobus ◽  
Y.C. Loraine Tung ◽  
...  
Keyword(s):  
Food Intake ◽  
Human Chromosome ◽  
Nuclear Membrane ◽  
Genetic Variants ◽  
Molecular Mechanisms ◽  
Transmembrane Protein ◽  
Strong Association ◽  
Nuclear Pore ◽  
Chromosome 2 ◽  
The Impact

AbstractAn intergenic region of human Chromosome 2 (2p25.3) harbours genetic variants which are among those most strongly and reproducibly associated with obesity. The molecular mechanisms mediating these effects remain entirely unknown. The gene closest to these variants is TMEM18, encoding a transmembrane protein localised to the nuclear membrane. The expression of Tmem18 within the murine hypothalamic paraventricular nucleus was altered by changes in nutritional state, with no significant change seen in three other closest genes. Germline loss of Tmem18 in mice resulted in increased body weight, which was exacerbated by high fat diet and driven by increased food intake. Selective overexpression of Tmem18 in the PVN of wild-type mice reduced food intake and also increased energy expenditure. We confirmed the nuclear membrane localisation of TMEM18 but provide new evidence that it is has four, not three, transmembrane domains and that it physically interacts with key components of the nuclear pore complex. Our data support the hypothesis that TMEM18 itself, acting within the central nervous system, is a plausible mediator of the impact of adjacent genetic variation on human adiposity.

scholarly journals TIP60 governs the auto-ubiquitination of UHRF1 through USP7 dissociation from the UHRF1/USP7 complex

2020 ◽  
Author(s):  
Tanveer Ahmad ◽  
Waseem Ashraf ◽  
Abdulkhaleg Ibrahim ◽  
Liliyana Zaayter ◽  
Christian D. Muller ◽  
...  
Keyword(s):  
Dna Methyltransferase ◽  
Ring Finger ◽  
Fluorescence Lifetime Imaging ◽  
Cellular Functions ◽  
Apoptotic Pathway ◽  
Cellular Processes ◽  
Lifetime Imaging ◽  
Damage Repair ◽  
Microscopy Techniques

Abstract Background: The epigenetic regulator UHRF1 (Ubiquitin-like, containing PHD and RING finger domains 1) plays an essential role in faithful transmission of DNA methylation during replication. It has tumorogenesis potential and is overexpressed in cancers. TIP60 (Tat interactive protein, 60 kDa) is an important partner of UHRF1, ensuring various cellular processes through its acetyltransferase activity. TIP60 is believed to exert a tumor suppressive role partly explained by its down-regulation in many cancers. Both proteins participate in various cellular functions such as chromatin remodeling, cell cycle, DNA damage repair and regulation of protein stability.Methods: Immunoprecipitation and confocal microscopy techniques were performed to study the ubiquitination of UHRF1 and USP-UHRF1 association. Fluorescence lifetime imaging microscopy (FLIM) technique was performed to analyze the interaction between UHRF1 and ubiquitin inside the nucleus. Western blotting was used to assess the effect of TIP60 overexpression on p73, pro- and anti-apoptotic proteins. TIP60-mediated apoptosis in HeLa cells was investigated by flow cytometry. Results were statistically analyzed using Graphpad prism.Results: Herein, our goal was to investigate the role and mechanism of TIP60 in the regulation of UHRF1 expression. Our results showed that TIP60 overexpression down-regulated UHRF1 and DNMT1 (DNA methyltransferase 1) expressions. TIP60 interfered with USP7-UHRF1 association and induced degradation of UHRF1 in an auto-ubiquitination dependent pathway. Moreover, TIP60 activated the p73-mediated apoptotic pathway.Conclusion: Taken together, our data suggest that the tumor suppressor role of TIP60 is mediated by its regulation to UHRF1.

An Overview of HDAC Inhibitors and their Synthetic Routes

2019 ◽  
Vol 19 (12) ◽  
pp. 1005-1040 ◽  
Author(s):  
Xiaopeng Peng ◽  
Guochao Liao ◽  
Pinghua Sun ◽  
Zhiqiang Yu ◽  
Jianjun Chen
Keyword(s):  
Histone Acetylation ◽  
Histone Deacetylases ◽  
Histone Deacetylase Inhibitors ◽  
Cell Cycle Control ◽  
Hdac Inhibitors ◽  
Cancer Therapeutics ◽  
Cellular Processes ◽  
Chaperone Function ◽  
Damage Repair ◽  
Synthetic Routes

Epigenetics play a key role in the origin, development and metastasis of cancer. Epigenetic processes include DNA methylation, histone acetylation, histone methylation, and histone phosphorylation, among which, histone acetylation is the most common one that plays important roles in the regulation of normal cellular processes, and is controlled by histone deacetylases (HDACs) and histone acetyltransferases (HATs). HDACs are involved in the regulation of many key cellular processes, such as DNA damage repair, cell cycle control, autophagy, metabolism, senescence and chaperone function, and can lead to oncogene activation. As a result, HDACs are considered to be an excellent target for anti-cancer therapeutics like histone deacetylase inhibitors (HDACi) which have attracted much attention in the last decade. A wide-ranging knowledge of the role of HDACs in tumorigenesis, and of the action of HDACi, has been achieved. The primary purpose of this paper is to summarize recent HDAC inhibitors and the synthetic routes as well as to discuss the direction for the future development of new HDAC inhibitors.

scholarly journals Degradation of the Tumor Suppressor PML by Pin1 Contributes to the Cancer Phenotype of Breast Cancer MDA-MB-231 Cells

2007 ◽  
Vol 28 (3) ◽  
pp. 997-1006 ◽  
Author(s):  
Erin L. Reineke ◽  
Minh Lam ◽  
Qing Liu ◽  
Yu Liu ◽  
Kristopher J. Stanya ◽  
...  
Keyword(s):  
Breast Cancer ◽  
Cancer Cell Line ◽  
Dependent Manner ◽  
Cellular Functions ◽  
Cellular Processes ◽  
C Terminus ◽  
Damage Repair ◽  
Numerous Cell ◽  
Steady State Levels ◽  
Cycle Regulation

ABSTRACT Promyelocytic leukemia protein (PML) is an important regulator due to its role in numerous cellular processes including apoptosis, viral infection, senescence, DNA damage repair, and cell cycle regulation. Despite the role of PML in many cellular functions, little is known about the regulation of PML itself. We show that PML stability is regulated through interaction with the peptidyl-prolyl cis-trans isomerase Pin1. This interaction is mediated through four serine-proline motifs in the C terminus of PML. Binding to Pin1 results in degradation of PML in a phosphorylation-dependent manner. Furthermore, our data indicate that sumoylation of PML blocks the interaction, thus preventing degradation of PML by this pathway. Functionally, we show that in the MDA-MB-231 breast cancer cell line modulating levels of Pin1 affects steady-state levels of PML. Furthermore, degradation of PML due to Pin1 acts both to protect these cells from hydrogen peroxide-induced death and to increase the rate of proliferation. Taken together, our work defines a novel mechanism by which sumoylation of PML prevents Pin1-dependent degradation. This interaction likely occurs in numerous cell lines and may be a pathway for oncogenic transformation.

The Formation, Structure, Distribution and Frequency of Nuclear Pores

1971 ◽  
Vol 29 ◽  
pp. 518-519
Author(s):  
G. G. Maul
Keyword(s):  
Nuclear Pore Complex ◽  
Nuclear Membrane ◽  
Dynamic Structure ◽  
Nuclear Pore ◽  
Nuclear Pores ◽  
Filter Function ◽  
Etching Technique ◽  
Selective Filter ◽  
Membranous Part

The chromatin of eukaryotic cells is separated from the cytoplasm by a double membrane. One obvious structural specialization of the nuclear membrane is the presence of pores which have been implicated to facilitate the selective nucleocytoplasmic exchange of a variety of large molecules. Thus, the function of nuclear pores has mainly been regarded to be a passive one. Non-membranous diaphragms, radiating fibers, central rings, and other pore-associated structures were thought to play a role in the selective filter function of the nuclear pore complex. Evidence will be presented that suggests that the nuclear pore is a dynamic structure which is non-randomly distributed and can be formed during interphase, and that a close relationship exists between chromatin and the membranous part of the nuclear pore complex.Octagonality of the nuclear pore complex has been confirmed by a variety of techniques. Using the freeze-etching technique, it was possible to show that the membranous part of the pore complex has an eight-sided outline in human melanoma cells in vitro. Fibers which traverse the pore proper at its corners are continuous and indistinguishable from chromatin at the nucleoplasmic side, as seen in conventionally fixed and sectioned material. Chromatin can be seen in octagonal outline if serial sections are analyzed which are parallel but do not include nuclear membranes (Fig. 1). It is concluded that the shape of the pore rim is due to fibrous material traversing the pore, and may not have any functional significance. In many pores one can recognize a central ring with eight fibers radiating to the corners of the pore rim. Such a structural arrangement is also found to connect eight ribosomes at the nuclear membrane.

scholarly journals Bend, Push, Stretch: Remarkable Structure and Mechanics of Single Intermediate Filaments and Meshworks

Cells ◽  
2021 ◽  
Vol 10 (8) ◽  
pp. 1960
Author(s):  
K. Tanuj Sapra ◽  
Ohad Medalia
Keyword(s):  
Intermediate Filaments ◽  
Eukaryotic Cell ◽  
Coiled Coils ◽  
Cellular Functions ◽  
Mechanical Pressure ◽  
Mechanical Feature ◽  
Cellular Processes ◽  
Nuclear Lamins ◽  
Filament Networks ◽  
And Function

The cytoskeleton of the eukaryotic cell provides a structural and functional scaffold enabling biochemical and cellular functions. While actin and microtubules form the main framework of the cell, intermediate filament networks provide unique mechanical properties that increase the resilience of both the cytoplasm and the nucleus, thereby maintaining cellular function while under mechanical pressure. Intermediate filaments (IFs) are imperative to a plethora of regulatory and signaling functions in mechanotransduction. Mutations in all types of IF proteins are known to affect the architectural integrity and function of cellular processes, leading to debilitating diseases. The basic building block of all IFs are elongated α-helical coiled-coils that assemble hierarchically into complex meshworks. A remarkable mechanical feature of IFs is the capability of coiled-coils to metamorphize into β-sheets under stress, making them one of the strongest and most resilient mechanical entities in nature. Here, we discuss structural and mechanical aspects of IFs with a focus on nuclear lamins and vimentin.

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