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Publications in Cell Nucleus Membrane by NOMIS researchers

Caspase-mediated nuclear pore complex trimming in cell differentiation and endoplasmic reticulum stress

NOMIS Researcher(s)

Published in

September 4, 2023

During apoptosis, caspases degrade 8 out of ~30 nucleoporins to irreversibly demolish the nuclear pore complex. However, for poorly understood reasons, caspases are also activated during cell differentiation. Here, we show that sublethal activation of caspases during myogenesis results in the transient proteolysis of four peripheral Nups and one transmembrane Nup. ‘Trimmed’ NPCs become nuclear export-defective, and we identified in an unbiased manner several classes of cytoplasmic, plasma membrane, and mitochondrial proteins that rapidly accumulate in the nucleus. NPC trimming by non-apoptotic caspases was also observed in neurogenesis and endoplasmic reticulum stress. Our results suggest that caspases can reversibly modulate nuclear transport activity, which allows them to function as agents of cell differentiation and adaptation at sublethal levels. © 2023, eLife Sciences Publications Ltd. All rights reserved.

Research field(s)
Health Sciences

DOI
10.7554/eLife.89066

Lipid saturation controls nuclear envelope function

NOMIS Researcher(s)

Published in

August 17, 2023

The nuclear envelope (NE) is a spherical double membrane with elastic properties. How NE shape and elasticity are regulated by lipid chemistry is unknown. Here we discover lipid acyl chain unsaturation as essential for NE and nuclear pore complex (NPC) architecture and function. Increased lipid saturation rigidifies the NE and the endoplasmic reticulum into planar, polygonal membranes, which are fracture prone. These membranes exhibit a micron-scale segregation of lipids into ordered and disordered phases, excluding NPCs from the ordered phase. Balanced lipid saturation is required for NPC integrity, pore membrane curvature and nucleocytoplasmic transport. Oxygen deprivation amplifies the impact of saturated lipids, causing NE rigidification and rupture. Conversely, lipid droplets buffer saturated lipids to preserve NE architecture. Our study uncovers a fundamental link between lipid acyl chain structure and the integrity of the cell nucleus with implications for nuclear membrane malfunction in ischaemic tissues. © 2023, The Author(s).

Research field(s)
Natural Sciences

DOI
10.1038/s41556-023-01207-8

Nuclear pore complex maintenance and implications for age-related diseases

NOMIS Researcher(s)

Published in

March 1, 2022

Nuclear pore complexes (NPCs) bridge the nucleus and the cytoplasm and are indispensable for crucial cellular activities, such as bidirectional molecular trafficking and gene transcription regulation. The discovery of long-lived proteins (LLPs) in NPCs from postmitotic cells raises the exciting possibility that the maintenance of NPC integrity might play an inherent role in lifelong cell function. Age-dependent deterioration of NPCs and loss of nuclear integrity have been linked to age-related decline in postmitotic cell function and degenerative diseases. In this review, we discuss our current understanding of NPC maintenance in proliferating and postmitotic cells, and how malfunction of nucleoporins (Nups) might contribute to the pathogenesis of various neurodegenerative and cardiovascular diseases.

Research field(s)
Health Sciences, Biomedical Research, Developmental Biology

DOI
10.1016/j.tcb.2021.10.001

Nuclear Periphery Takes Center Stage: The Role of Nuclear Pore Complexes in Cell Identity and Aging

NOMIS Researcher(s)

Published in

June 17, 2020

In recent years, the nuclear pore complex (NPC) has emerged as a key player in genome regulation and cellular homeostasis. New discoveries have revealed that the NPC has multiple cellular functions besides mediating the molecular exchange between the nucleus and the cytoplasm. In this review, we discuss non-transport aspects of the NPC focusing on the NPC-genome interaction, the extreme longevity of the NPC proteins, and NPC dysfunction in age-related diseases. The examples summarized herein demonstrate that the NPC, which first evolved to enable the biochemical communication between the nucleus and the cytoplasm, now doubles as the gatekeeper of cellular identity and aging. Cho and Hetzer discuss recent studies that have established the nuclear pore complex as a key regulator of transcription control of cell identity genes and have linked its functional decline to premature, physiological, and pathological aging.

Research field(s)
Health Sciences, Clinical Medicine, Neurology & Neurosurgery

DOI
10.1016/j.neuron.2020.05.031

Nup93 regulates breast tumor growth by modulating cell proliferation and actin cytoskeleton remodeling

NOMIS Researcher(s)

Published in

January 20, 2020

Nucleoporin 93 (Nup93) expression inversely correlates with the survival of triple-negative breast cancer patients. However, our knowledge of Nup93 function in breast cancer besides its role as structural component of the nuclear pore complex is not understood. Combination of functional assays and genetic analyses suggested that chromatin interaction of Nup93 partially modulates the expression of genes associated with actin cytoskeleton remodeling and epithelial to mesenchymal transition, resulting in impaired invasion of triple-negative, claudin-low breast cancer cells. Nup93 depletion induced stress fiber formation associated with reduced cell migration/proliferation and impaired expression of mesenchymal-like genes. Silencing LIMCH1, a gene responsible for actin cytoskeleton remodeling and up-regulated upon Nup93 depletion, partially restored the invasive phenotype of cancer cells. Loss of Nup93 led to significant defects in tumor establishment/propagation in vivo, whereas patient samples revealed that high Nup93 and low LIMCH1 expression correlate with late tumor stage. Our approach identified Nup93 as contributor of triple-negative, claudin-low breast cancer cell invasion and paves the way to study the role of nuclear envelope proteins during breast cancer tumorigenesis.

Research field(s)
Health Sciences, Biomedical Research, Developmental Biology

DOI
10.26508/LSA.201900623

Visualization of long-lived proteins reveals age mosaicism within nuclei of postmitotic cells

NOMIS Researcher(s)

Published in

February 1, 2019

Many adult tissues contain postmitotic cells as old as the host organism. Te only organelle that does not turn over in these cells is the nucleus, and its maintenance represents a formidable challenge, as it harbors regulatory proteins that persist throughout adulthood. Here we developed strategies to visualize two classes of such long-lived proteins, histones and nucleoporins, to understand the function of protein longevity in nuclear maintenance. Genome-wide mapping of histones revealed specifc enrichment of long-lived variants at silent gene loci. Interestingly, nuclear pores are maintained by piecemeal replacement of subunits, resulting in mosaic complexes composed of polypeptides with vastly different ages. In contrast, nondividing quiescent cells remove old nuclear pores in an ESCRT-dependent manner. Our fndings reveal distinct molecular strategies of nuclear maintenance, linking lifelong protein persistence to gene regulation and nuclear integrity.

Research field(s)
Health Sciences, Biomedical Research, Developmental Biology

DOI
10.1083/jcb.201809123

Tpr regulates the total number of nuclear pore complexes per cell nucleus

NOMIS Researcher(s)

Published in

January 1, 2018

The total number of nuclear pore complexes (NPCs) per nucleus varies greatly between different cell types and is known to change during cell differentiation and cell transformation. However, the underlying mechanisms that control how many nuclear transport channels are assembled into a given nuclear envelope remain unclear. Here, we report that depletion of the NPC basket protein Tpr, but not Nup153, dramatically increases the total NPC number in various cell types. This negative regulation of Tpr occurs via a phosphorylation cascade of extracellular signal-regulated kinase (ERK), the central kinase of the mitogen-activated protein kinase (MAPK) pathway. Tpr serves as a scaffold for ERK to phosphorylate the nucleoporin (Nup) Nup153, which is critical for early stages of NPC biogenesis. Our results reveal a critical role of the Nup Tpr in coordinating signal transduction pathways during cell proliferation and the dynamic organization of the nucleus.

Research field(s)
Health Sciences, Biomedical Research, Developmental Biology

DOI
10.1101/GAD.315523.118

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