bims-nucpor 2021-06-06 papers

Issue of 2021–06–06
five papers selected by
Sara Mingu, Johannes Gutenberg University

Nat Neurosci. 2021 May 31.

Interactions between ALS-linked FUS and nucleoporins are associated with defects in the nucleocytoplasmic transport pathway.

Yen-Chen Lin, Meenakshi Sundaram Kumar, Nandini Ramesh, Eric N Anderson, Aivi T Nguyen, Boram Kim, Simon Cheung, Justin A McDonough, William C Skarnes, Rodrigo Lopez-Gonzalez, John E Landers, Nicolas L Fawzi, Ian R A Mackenzie, Edward B Lee, Jeffrey A Nickerson, David Grunwald, Udai B Pandey, Daryl A Bosco.

Nucleocytoplasmic transport (NCT) decline occurs with aging and neurodegeneration. Here, we investigated the NCT pathway in models of amyotrophic lateral sclerosis-fused in sarcoma (ALS-FUS). Expression of ALS-FUS led to a reduction in NCT and nucleoporin (Nup) density within the nuclear membrane of human neurons. FUS and Nups were found to interact independently of RNA in cells and to alter the phase-separation properties of each other in vitro. FUS-Nup interactions were not localized to nuclear pores, but were enriched in the nucleus of control neurons versus the cytoplasm of mutant neurons. Our data indicate that the effect of ALS-linked mutations on the cytoplasmic mislocalization of FUS, rather than on the physiochemical properties of the protein itself, underlie our reported NCT defects. An aberrant interaction between mutant FUS and Nups is underscored by studies in Drosophila, whereby reduced Nup expression rescued multiple toxic FUS-induced phenotypes, including abnormal nuclear membrane morphology in neurons.

DOI: https://doi.org/10.1038/s41593-021-00859-9

Elife. 2021 May 26. pii: e67587. [Epub ahead of print]10

Traumatic injury compromises nucleocytoplasmic transport and leads to TDP-43 pathology.

Eric N Anderson, Andrés A Morera, Sukhleen Kour, Jonathan D Cherry, Nandini Ramesh, Amanda Gleixner, Jacob C Schwartz, Christopher Ebmeier, William Old, Christopher J Donnelly, Jeffrey P Cheng, Anthony E Kline, Julia Kofler, Thor D Stein, Udai Bhan Pandey.

Traumatic brain injury (TBI) is a predisposing factor for many neurodegenerative diseases, including amyotrophic lateral sclerosis (ALS), Alzheimer's disease (AD), Parkinson's disease (PD), and chronic traumatic encephalopathy (CTE). Although defects in nucleocytoplasmic transport (NCT) is reported ALS and other neurodegenerative diseases, whether defects in NCT occur in TBI remains unknown. We performed proteomic analysis on Drosophila exposed to repeated TBI and identified resultant alterations in several novel molecular pathways. TBI upregulated nuclear pore complex (NPC) and nucleocytoplasmic transport (NCT) proteins as well as alter nucleoporin stability. Traumatic injury disrupted RanGAP1 and NPC protein distribution in flies and a rat model and led to coaggregation of NPC components and TDP-43. In addition, trauma-mediated NCT defects and lethality are rescued by nuclear export inhibitors. Importantly, genetic upregulation of nucleoporins in vivo and in vitro triggered TDP-43 cytoplasmic mislocalization, aggregation, and altered solubility and reduced motor function and lifespan of animals. We also found NUP62 pathology and elevated NUP62 concentrations in postmortem brain tissues of patients with mild or severe CTE as well as co-localization of NUP62 and TDP-43 in CTE. These findings indicate that TBI leads to NCT defects, which potentially mediate the TDP-43 pathology in CTE.

Keywords: D. melanogaster; TDP-43; amyotrophic lateral sclerosis; chronic traumatic encephalopathy; genetics; genomics; human; neurodegeneration; neuroscience; rat

DOI: https://doi.org/10.7554/eLife.67587

Cells. 2021 May 21. pii: 1271. [Epub ahead of print]10(6):

Nucleoporin TPR Affects C2C12 Myogenic Differentiation via Regulation of Myh4 Expression.

Jana Uhlířová, Lenka Šebestová, Karel Fišer, Tomáš Sieger, Jindřiška Fišerová, Pavel Hozák.

The nuclear pore complex (NPC) has emerged as a hub for the transcriptional regulation of a subset of genes, and this type of regulation plays an important role during differentiation. Nucleoporin TPR forms the nuclear basket of the NPC and is crucial for the enrichment of open chromatin around NPCs. TPR has been implicated in the regulation of transcription; however, the role of TPR in gene expression and cell differentiation has not been described. Here we show that depletion of TPR results in an aberrant morphology of murine proliferating C2C12 myoblasts (MBs) and differentiated C2C12 myotubes (MTs). The ChIP-Seq data revealed that TPR binds to genes linked to muscle formation and function, such as myosin heavy chain (Myh4), myocyte enhancer factor 2C (Mef2C) and a majority of olfactory receptor (Olfr) genes. We further show that TPR, possibly via lysine-specific demethylase 1 (LSD1), promotes the expression of Myh4 and Olfr376, but not Mef2C. This provides a novel insight into the mechanism of myogenesis; however, more evidence is needed to fully elucidate the mechanism by which TPR affects specific myogenic genes.

Keywords: LSD1; Myh4; Olfr; TPR; gene expression; myogenic differentiation; nucleoporin; translocated promoter region

DOI: https://doi.org/10.3390/cells10061271

Cell Biosci. 2021 Jun 01. 11(1): 102

Subcellular localization of the mouse PRAMEL1 and PRAMEX1 reveals multifaceted roles in the nucleus and cytoplasm of germ cells during spermatogenesis.

Wan-Sheng Liu, Chen Lu, Bhavesh V Mistry.

BACKGROUND: Preferentially expressed antigen in melanoma (PRAME) is a cancer/testis antigen (CTA) that is predominantly expressed in normal gametogenic tissues and a variety of tumors. Members of the PRAME gene family encode leucine-rich repeat (LRR) proteins that provide a versatile structural framework for the formation of protein-protein interactions. As a nuclear receptor transcriptional regulator, PRAME has been extensively studied in cancer biology and is believed to play a role in cancer cell proliferation by suppressing retinoic acid (RA) signaling. The role of the PRAME gene family in germline development and spermatogenesis has been recently confirmed by a gene knockout approach. To further understand how PRAME proteins are involved in germ cell development at a subcellular level, we have conducted a systematic immunogold electron microscopy (IEM) analysis on testis sections of adult mice with gene-specific antibodies from two members of the mouse Prame gene family: Pramel1 and Pramex1. Pramel1 is autosomal, while Pramex1 is X-linked, both genes are exclusively expressed in the testis.
RESULTS: Our IEM data revealed that both PRAMEL1 and PRAMEX1 proteins were localized in various cell organelles in different development stages of spermatogenic cells, including the nucleus, rER, Golgi, mitochondria, germ granules [intermitochondrial cement (IMC) and chromatoid body (CB)], centrioles, manchette, and flagellum. Unlike other germ cell-specific makers, such as DDX4, whose proteins are evenly distributed in the expressed-organelle(s), both PRAMEL1 and PRAMEX1 proteins tend to aggregate together to form clusters of protein complexes. These complexes were highly enriched in the nucleus and cytoplasm (especially in germ granules) of spermatocytes and spermatids. Furthermore, dynamic distribution of the PRAMEL1 protein complexes were observed in the microtubule-based organelles, such as acroplaxome, manchette, and flagellum, as well as in the nuclear envelope and nuclear pore. Dual staining with PRAMEL1 and KIF17B antibodies further revealed that the PRAMEL1 and KIF17B proteins were co-localized in germ granules.
CONCLUSION: Our IEM data suggest that the PRAMEL1 and PRAMEX1 proteins are not only involved in transcriptional regulation in the nucleus, but may also participate in nucleocytoplasmic transport, and in the formation and function of germ cell-specific organelles during spermatogenesis.

Keywords: Cancer-testis antigen; Chromatoid body; Germ cell; Germ granule; Immunoelectron microscopy; Nucleocytoplasmic transport; PRAMEL1; PRAMEX1; Spermatogenesis; Testis

DOI: https://doi.org/10.1186/s13578-021-00612-6

Viruses. 2021 May 04. pii: 829. [Epub ahead of print]13(5):

Role of Transportin-SR2 in HIV-1 Nuclear Import.

Maryam Tabasi, Ivan Nombela, Julie Janssens, Adrien P Lahousse, Frauke Christ, Zeger Debyser.

The HIV replication cycle depends on the interaction of viral proteins with proteins of the host. Unraveling host-pathogen interactions during the infection is of great importance for understanding the pathogenesis and the development of antiviral therapies. To date HIV uncoating and nuclear import are the most debated steps of the HIV-1 replication cycle. Despite numerous studies during past decades, there is still much controversy with respect to the identity and the role of viral and host factors involved in these processes. In this review, we provide a comprehensive overview on the role of transportin-SR2 as a host cell factor during active nuclear transport.

Keywords: CPSF6; HIV-1; TNPO3; TRN-SR2; capsid; integrase; nuclear import; transportin-SR2

DOI: https://doi.org/10.3390/v13050829