bims-nucpor 2022-05-29 papers

Issue of 2022‒05‒29
six papers selected by
Sara Mingu
Johannes Gutenberg University

Viral Immunol. 2022 May 23.

The Nuclear Pore Complex 62 Suppression Inhibits Coxsackievirus B Replication and Inflammatory Response.

Tingjun Liu, Yi Shi, Hua Wang, Hongxing Shen, Junyan Qu.

Coxsackievirus B3 (CVB3) is one of the major viruses associated with human viral myocarditis, in members of the Picornaviridae order. Cellular localization depends on the activity of nuclear pore complexes, which are composed of nucleoporins (Nups), including Nup62. To better understand interactions between Nup62 and CVB3, we investigated the impact of CVB3 infection on Nup62 levels and the impact of Nup62 production on CVB3 replication in cultured cells. We found that CVB3 infection correlated with decreased Nup62 expression in vitro and that lower levels of Nup62 led to inhibition of CVB3 replication and to decreased activation of AKT and extracellular signal-related kinase. Our study reveals that Nup62 regulates the CVB3 replication during infection.

Keywords: coxsackievirus B3; nucleoporin 62; virus infection

DOI: https://doi.org/10.1089/vim.2021.0194

Int J Mol Sci. 2022 May 13. pii: 5451. [Epub ahead of print]23(10):

Nuclear mRNA Export and Aging.

Hyun-Sun Park, Jongbok Lee, Hyun-Shik Lee, Seong Hoon Ahn, Hong-Yeoul Ryu.

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.

Keywords: NPC; TREX; TREX-2; lifespan; mRNA export; neurodegenerative diseases

DOI: https://doi.org/10.3390/ijms23105451

Mol Biol Cell. 2022 May 24. mbcE22020037

ZC3HC1 is a structural element of the nuclear basket effecting interlinkage of TPR polypeptides.

Philip Gunkel, Volker C Cordes.

The nuclear basket (NB), anchored to the nuclear pore complex (NPC), is commonly looked upon as a structure built solely of protein TPR polypeptides, the latter thus regarded as the NB's only scaffold-forming components. In the current study, we report ZC3HC1 as a second structural element of the NB. Recently described as an NB-appended protein omnipresent in vertebrates, we now show that ZC3HC1, both in vivo and in vitro, enables in a stepwise fashion the recruitment of TPR subpopulations to the NB and their linkage to already NPC-anchored TPR polypeptides. We further demonstrate that the degron-mediated rapid elimination of ZC3HC1 results in the prompt detachment of the ZC3HC1-appended TPR polypeptides from the NB and their release into the nucleoplasm, underscoring the role of ZC3HC1 as a natural structural element of the NB. Finally, we show that ZC3HC1 can keep TPR polypeptides positioned and linked to each other even at sites remote from the NB, in line with ZC3HC1 functioning as a protein connecting TPR polypeptides.

DOI: https://doi.org/10.1091/mbc.E22-02-0037

Biomolecules. 2022 May 12. pii: 695. [Epub ahead of print]12(5):

Clade-Specific Alterations within the HIV-1 Capsid Protein with Implications for Nuclear Translocation.

Alexej Dick, Megan E Meuser, Simon Cocklin.

The HIV-1 capsid (CA) protein has emerged as an attractive therapeutic target. However, all inhibitor designs and structural analyses for this essential HIV-1 protein have focused on the clade B HIV-1 (NL4-3) variant. This study creates, overproduces, purifies, and characterizes the CA proteins from clade A1, A2, B, C, and D isolates. These new CA constructs represent novel reagents that can be used in future CA-targeted inhibitor design and to investigate CA proteins' structural and biochemical properties from genetically diverse HIV-1 subtypes. Moreover, we used surface plasmon resonance (SPR) spectrometry and computational modeling to examine inter-clade differences in CA assembly and binding of PF-74, CPSF-6, and NUP-153. Interestingly, we found that HIV-1 CA from clade A1 does not bind to NUP-153, suggesting that the import of CA core structures through the nuclear pore complex may be altered for viruses from this clade. Overall, we have demonstrated that in silico generated models of the HIV-1 CA protein from clades other than the prototypically used clade B have utility in understanding and predicting biology and antiviral drug design and mechanism of action.

Keywords: CPSF-6; HIV-1 capsid protein; NUP-153; assembly; nuclear import factor recognition; surface plasmon resonance

DOI: https://doi.org/10.3390/biom12050695

Biomedicines. 2022 May 03. pii: 1057. [Epub ahead of print]10(5):

Cellular Stress Induces Nucleocytoplasmic Transport Deficits Independent of Stress Granules.

Joni Vanneste, Thomas Vercruysse, Steven Boeynaems, Philip Van Damme, Dirk Daelemans, Ludo Van Den Bosch.

Stress granules are non-membrane bound granules temporarily forming in the cytoplasm in response to stress. Proteins of the nucleocytoplasmic transport machinery were found in these stress granules and it was suggested that stress granules contribute to the nucleocytoplasmic transport defects in several neurodegenerative disorders, including amyotrophic lateral sclerosis (ALS). The aim of this study was to investigate whether there is a causal link between stress granule formation and nucleocytoplasmic transport deficits. Therefore, we uncoupled stress granule formation from cellular stress while studying nuclear import. This was carried out by preventing cells from assembling stress granules despite being subjected to cellular stress either by knocking down both G3BP1 and G3BP2 or by pharmacologically inhibiting stress granule formation. Conversely, we induced stress granules by overexpressing G3BP1 in the absence of cellular stress. In both conditions, nuclear import was not affected demonstrating that stress granule formation is not a direct cause of stress-induced nucleocytoplasmic transport deficits.

Keywords: amyotrophic lateral sclerosis; arsenite; neurodegeneration; nuclear import

DOI: https://doi.org/10.3390/biomedicines10051057

Curr Biol. 2022 May 18. pii: S0960-9822(22)00664-9. [Epub ahead of print]

MEL-28/ELYS and CENP-C coordinately control outer kinetochore assembly and meiotic chromosome-microtubule interactions.

Neil Hattersley, Aleesa J Schlientz, Bram Prevo, Karen Oegema, Arshad Desai.

During mitosis and meiosis in the majority of eukaryotes, centromeric chromatin comprised of CENP-A nucleosomes and their reader CENP-C recruits components of the outer kinetochore to build an interface with spindle microtubules.1,2 One exception is C. elegans oocyte meiosis, where outer kinetochore proteins form cup-like structures on chromosomes independently of centromeric chromatin.3 Here, we show that the nucleoporin MEL-28 (ortholog of human ELYS) and CENP-CHCP-4 act in parallel to recruit outer kinetochore components to oocyte meiotic chromosomes. Unexpectedly, co-inhibition of MEL-28 and CENP-CHCP-4 resulted in chromosomes being expelled from the meiotic spindle prior to anaphase onset, a more severe phenotype than what was observed following ablation of the outer kinetochore.4,5 This observation suggested that MEL-28 and the outer kinetochore independently link chromosomes to spindle microtubules. Consistent with this, the chromosome expulsion defect was observed following co-inhibition of MEL-28 and the microtubule-coupling KNL-1/MIS-12/NDC-80 (KMN) network of the outer kinetochore. Use of engineered mutants showed that MEL-28 acts in conjunction with the microtubule-binding NDC-80 complex to keep chromosomes within the oocyte meiotic spindle and that this function likely involves the Y-complex of nucleoporins that associate with MEL-28; by contrast, the ability to dock protein phosphatase 1, shared by MEL-28 and KNL-1, is not involved. These results highlight nuclear pore-independent functions for a conserved nucleoporin and explain two unusual features of oocyte meiotic chromosome segregation in C. elegans: centromeric chromatin-independent outer kinetochore assembly, and dispensability of the outer kinetochore for constraining chromosomes in the acentrosomal meiotic spindle.

Keywords: C. elegans; CENPA; CENPC; ELYS; KMN network; NDC80; centromere; kinetochore; meiosis; nuclear pore; oocyte; spindle

DOI: https://doi.org/10.1016/j.cub.2022.04.046