The molecular architecture of the nuclear pore complex

Nuclear envelope components in vascular mechanotransduction: emerging roles in vascular health and disease

The vascular network, uniquely sensitive to mechanical changes, translates biophysical forces into biochemical signals for vessel function. This process relies on the cell's architectural integrity, enabling uniform responses to physical stimuli. Recently, the nuclear envelope (NE) has emerged as a key regulator of vascular cell function. Studies implicate nucleoskeletal elements (e.g. nuclear lamina) and the linker of nucleoskeleton and cytoskeleton (LINC) complex in force transmission, emphasizing nucleo-cytoskeletal communication in mechanotransduction. The nuclear pore complex (NPC) and its component proteins (i.e. nucleoporins) also play roles in cardiovascular disease (CVD) progression. We herein summarize evidence on the roles of nuclear lamina proteins, LINC complex members, and nucleoporins in endothelial and vascular cell mechanotransduction. Numerous studies attribute NE components in cytoskeletal-related cellular behaviors to insinuate dysregulation of nucleocytoskeletal feedback and nucleocytoplasmic transport as a mechanism of endothelial and vascular dysfunction, and hence implications for aging and vascular pathophysiology.

A ROS-Responsive nanoparticle for nuclear gene delivery and autophagy restoration in Parkinson's disease therapy

Parkinson's disease (PD) is characterized by the pathological aggregation of α-synuclein (α-syn) and neuroinflammation. Current gene therapies face challenges in nuclear delivery and resolving pre-existing α-syn aggregates. Here, we developed glucose-and trehalose-functionalized carbonized polymer dots (GT-PCDs) loaded with plasmid DNA (pDNA) for targeted gene delivery and autophagy restoration. The GT-PCDs@pDNA nanoparticles exhibit reactive oxygen species (ROS)-responsive behavior, enabling efficient nuclear entry under oxidative stress conditions. Both in vitro and in vivo studies demonstrated that GT-PCDs@pDNA effectively silenced SNCA gene expression, reduced α-syn aggregates, and restored autophagic flux by promoting transcription factor EB (TFEB) nuclear translocation. Moreover, GT-PCDs@pDNA enhanced blood-brain barrier (BBB) permeability via glucose transporter 1 (Glut-1)-mediated transcytosis, significantly improving motor deficits and reducing neuroinflammation in a 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced PD mouse model. This multifunctional nanocarrier system offers a promising strategy for combined gene therapy and autophagy modulation in neurodegenerative diseases.

Nanopores with an Engineered Selective Entropic Gate Detect Proteins at Nanomolar Concentration in Complex Biological Sample

Biological nanopores enable the electrical detection of biomolecules, making them ideal sensors for use in health-monitoring devices. Proteins are widely recognized as biomarkers for various diseases, but they present a unique challenge due to their vast diversity and concentration range in biological samples. Here, inspired by the nuclear pore complex, we incorporated a layer of disordered polypeptides into the biological nanopore YaxAB. This polypeptide mesh formed an entropic gate, significantly reducing the entry of proteins from a highly concentrated mixture, including blood. The introduction of a specific recognition element within the disordered polypeptides allowed targeted proteins to penetrate through the nanopores, where they were recognized by specific current signatures. This biosensing approach allowed for the recognition of nanomolar proteins directly from blood samples without prior sample preparation. This work paves the way for the next generation of nanopore sensors for the real-time detection of proteins in blood.

Bioenergetics and the Evolution of Cellular Traits

Evolutionary processes have transformed simple cellular life into a great diversity of forms, ranging from the ubiquitous eukaryotic cell design to the more specific cellular forms of spirochetes, cyanobacteria, ciliates, heliozoans, amoeba, and many others. The cellular traits that constitute these forms require an evolutionary explanation. Ultimately, the persistence of a cellular trait depends on its net contribution to fitness, a quantitative measure. Independent of any positive effects, a cellular trait exhibits a baseline energetic cost that needs to be accounted for when quantitatively examining its net fitness effect. Here, we explore how the energetic burden introduced by a cellular trait quantitatively affects cellular fitness, describe methods for determining cell energy budgets, summarize the costs of cellular traits across the tree of life, and examine how the fitness impacts of these energetic costs compare to other evolutionary forces and trait benefits.

Quitting Your Day Job in Response to Stress: Cell Survival and Cell Death Require Secondary Cytoplasmic Roles of Cyclin C and Med13

Following unfavorable environmental cues, cells reprogram pathways that govern transcription, translation, and protein degradation systems. This reprogramming is essential to restore homeostasis or commit to cell death. This review focuses on the secondary roles of two nuclear transcriptional regulators, cyclin C and Med13, which play key roles in this decision process. Both proteins are members of the Mediator kinase module (MKM) of the Mediator complex, which, under normal physiological conditions, positively and negatively regulates a subset of stress response genes. However, cyclin C and Med13 translocate to the cytoplasm following cell death or cell survival cues, interacting with a host of cell death and cell survival proteins, respectively. In the cytoplasm, cyclin C is required for stress-induced mitochondrial hyperfission and promotes regulated cell death pathways. Cytoplasmic Med13 stimulates the stress-induced assembly of processing bodies (P-bodies) and is required for the autophagic degradation of a subset of P-body assembly factors by cargo hitchhiking autophagy. This review focuses on these secondary, a.k.a. "night jobs" of cyclin C and Med13, outlining the importance of these secondary functions in maintaining cellular homeostasis following stress.

Interaction mapping between nucleoporins in the fission yeast Schizosaccharomyces pombe using mass-spectrometry

Nuclear pore complexes (NPCs) act as gateways across the nuclear envelope for molecular transport between the nucleus and the cytoplasm in eukaryotes. NPCs consist of several subcomplexes formed by multiple copies of approximately 30 different proteins known as nucleoporins (Nups). In the fission yeast Schizosaccharomyces pombe, the NPC structure is unique, particularly in its outer ring subcomplexes, where the cytoplasmic and nucleoplasmic outer rings are composed of distinct sets of proteins. However, it remains unclear how this unique outer ring structure in S. pombe is supported by interactions between subcomplexes or individual Nups. In this study, we investigated protein-protein interactions between S. pombe Nups using mass spectrometry and identified Nups that interact with each subcomplex or a specific Nup. The cytoplasmic outer ring Nups bind to both the cytoplasmic filament Nups and the inner ring Nups, while the nucleoplasmic outer ring Nups bind to the nuclear basket Nups in addition to the inner ring Nups. Among the inner ring Nups, Nup155 interacts with most of the cytoplasmic and nucleoplasmic outer ring Nups, suggesting that Nup155 may serve as a hub supporting the uniquely asymmetric outer ring structure of the S. pombe NPC.

Tutorial on integrative spatiotemporal modeling by integrative modeling platform

Cells function through dynamic interactions between macromolecules. Detailed characterization of the dynamics of large biomolecular systems is often not feasible by individual biophysical methods. In such cases, it may be possible to compute useful models by integrating multiple sources of information. We have previously developed an integrative method to model dynamic processes by computing biomolecular heterogeneity at fixed time points, then generating static integrative structural modes for each of these heterogeneity models, and finally connecting these static models to produce a scored trajectory model that depicts the process. Here, we demonstrate how to compute, score, and assess these integrative spatiotemporal models using our open-source Integrative Modeling Platform (IMP) program (https://integrativemodeling.org/).

Targeting colorectal cancer at the level of nuclear pore complex

BACKGROUND

Nuclear pore complexes (NPCs) are the architectures entrenched in nuclear envelop of a cell that regulate the nucleo-cytoplasmic transportation of materials, such as proteins and RNAs for proper functioning of a cell. The appropriate localization of proteins and RNAs within the cell is essential for its normal functionality. For such a complex transportation of materials across the NPC, around 60 proteins are involved comprising nucleoporins, karyopherins and RAN system proteins that play a vital role in NPC's structure formation, cargo translocation across NPC, and cargoes' rapid directed transportation respectively. In various cancers, the structure and function of NPC is often exaggerated, following altered expressions of its nucleoporins and karyopherins, affecting other proteins of associated signaling pathways. Some inhibitors of karyopherins at present, have potential to regulate the altered level/expression of these karyopherin molecules.

AIM OF REVIEW

This review summarizes the data from 1990 to 2023, mainly focusing on recent studies that illustrate the structure and function of NPC, the relationship and mechanisms of nucleoporins and karyopherins with colorectal cancer, as well as therapeutic values, in order to understand the pathology and underlying basis of colorectal cancer associated with NPC. This is the first review to our knowledge elucidating the detailed updated studies targeting colorectal cancer at NPC. The review also aims to target certain karyopherins, Nups and their possible inhibitors and activators molecules as a therapeutic strategy.

KEY SCIENTIFIC CONCEPTS OF REVIEW

NPC structure provides understanding, how nucleoporins and karyopherins as key molecules are responsible for appropriate nucleocytoplasmic transportation. Many studies provide evidences, describing the role of disrupted nucleoporins and karyopherins not only in CRC but also in other non-hematological and hematological malignancies. At present, some inhibitors of karyopherins have therapeutic potential for CRC, however development of more potent inhibitors may provide more effective therapeutic strategies for CRC in near future.

Aβ-driven nuclear pore complex dysfunction alters activation of necroptosis proteins in a mouse model of Alzheimer's disease

The emergence of Aβ pathology is one of the hallmarks of Alzheimer's disease (AD), but the mechanisms and impact of Aβ in progression of the disease is unclear. The nuclear pore complex (NPC) is a multi-protein assembly in mammalian cells that regulates movement of macromolecules across the nuclear envelope; its function is shown to undergo age-dependent decline during normal aging and is also impaired in multiple neurodegenerative disorders. Yet not much is known about the impact of Aβ on NPC function in neurons. Here, we examined NPC and nucleoporin (NUP) distribution and nucleocytoplasmic transport using a mouse model of AD (AppNL-G-F/NL-G-F) that expresses Aβ in young animals. Our studies revealed that a time-dependent accumulation of intracellular Aβ corresponded with a reduction of NPCs and NUPs in the nuclear envelope which resulted in the degradation of the permeability barrier and inefficient segregation of nucleocytoplasmic proteins, and active transport. As a result of the NPC dysfunction App KI neurons become more vulnerable to inflammation-induced necroptosis - a programmed cell death pathway where the core components are activated via phosphorylation through nucleocytoplasmic shutting. Collectively, our data implicates Aβ in progressive impairment of nuclear pore function and further confirms that the protein complex is vulnerable to disruption in various neurodegenerative diseases and is a potential therapeutic target.

Exportin-1 functions as an adaptor for transcription factor-mediated docking of chromatin at the nuclear pore complex

Nuclear pore proteins (nucleoporins [Nups]) physically interact with hundreds of chromosomal sites, impacting transcription. In yeast, transcription factors mediate interactions between Nups and enhancers and promoters. To define the molecular basis of this mechanism, we exploited a separation-of-function mutation in the Gcn4 transcription factor that blocks its interaction with the nuclear pore complex (NPC). This mutation reduces the interaction of Gcn4 with the highly conserved nuclear export factor Crm1/Xpo1. Crm1 and Nups co-occupy enhancers, and Crm1 inhibition blocks interaction of the nuclear pore protein Nup2 with the genome. In vivo, Crm1 interacts stably with the NPC and in vitro, Crm1 binds directly to both Gcn4 and Nup2. Importantly, the interaction between Crm1 and Gcn4 requires neither Ran-guanosine triphosphate (GTP) nor the nuclear export sequence binding site. Finally, Crm1 and Ran-GTP stimulate DNA binding by Gcn4, suggesting that allosteric coupling between Crm1-Ran-GTP binding and DNA binding facilitates the docking of transcription-factor-bound enhancers at the NPC.

Integrative spatiotemporal modeling of biomolecular processes: Application to the assembly of the nuclear pore complex

Dynamic processes involving biomolecules are essential for the function of the cell. Here, we introduce an integrative method for computing models of these processes based on multiple heterogeneous sources of information, including time-resolved experimental data and physical models of dynamic processes. First, for each time point, a set of coarse models of compositional and structural heterogeneity is computed (heterogeneity models). Second, for each heterogeneity model, a set of static integrative structure models is computed (a snapshot model). Finally, these snapshot models are selected and connected into a series of trajectories that optimize the likelihood of both the snapshot models and transitions between them (a trajectory model). The method is demonstrated by application to the assembly process of the human nuclear pore complex in the context of the reforming nuclear envelope during mitotic cell division, based on live-cell correlated electron tomography, bulk fluorescence correlation spectroscopy-calibrated quantitative live imaging, and a structural model of the fully assembled nuclear pore complex. Modeling of the assembly process improves the model precision over static integrative structure modeling alone. The method is applicable to a wide range of time-dependent systems in cell biology and is available to the broader scientific community through an implementation in the open source Integrative Modeling Platform (IMP) software.

Post-Transcriptional Regulation of Gene Expression and the Intricate Life of Eukaryotic mRNAs

In recent years, there has been a growing appreciation for how regulatory events that occur either co- or post-transcriptionally contribute to the control of gene expression. Messenger RNAs (mRNAs) are extensively regulated throughout their metabolism in a precise spatiotemporal manner that requires sophisticated molecular mechanisms for cell-type-specific gene expression, which dictates cell function. Moreover, dysfunction at any of these steps can result in a variety of human diseases, including cancers, muscular atrophies, and neurological diseases. This review summarizes the steps of the central dogma of molecular biology, focusing on the post-transcriptional regulation of gene expression.

Integrative mapping reveals molecular features underlying the mechanism of nucleocytoplasmic transport

Nuclear Pore Complexes (NPCs) enable rapid, selective, and robust nucleocytoplasmic transport. To explain how transport emerges from the system components and their interactions, we used experimental data and theoretical information to construct an integrative Brownian dynamics model of transport through an NPC, coupled to a kinetic model of transport in the cell. The model recapitulates key aspects of transport for a wide range of molecular cargos, including pre-ribosomes and viral capsids. It quantifies how flexible phenylalanine-glycine (FG) repeat proteins raise an entropy barrier to passive diffusion and how this barrier is selectively lowered in facilitated diffusion by the many transient interactions of nuclear transport receptors with the FG repeats. Selective transport is enhanced by "fuzzy" multivalent interactions, redundant FG repeats, coupling to the energy-dependent RanGTP concentration gradient, and exponential dependence of transport kinetics on the transport barrier. Our model will facilitate rational modulation of the NPC and its artificial mimics.

Charge of karyopherins and nuclear FG-Nups are key ingredients of nucleocytoplasmic transport

The nuclear pore complex (NPC) is responsible for the selective transport of biomolecules in and out of the nucleus. This selective feature is achieved through intrinsically disordered proteins, FG-Nups, that are anchored to the inner wall of the NPC. Cargo smaller than approximately 5 nm can rapidly diffuse through the NPC whereas larger cargo is increasingly slowed down. Larger cargos bound to chaperone proteins (from the karyopherin or Kap family) can still be transported due to nonspecific interactions with the FG-Nups. Although various mechanisms for the transport of Kaps have been proposed, a consensus has still to be reached. Here, we conducted a coarse-grained molecular dynamics study to shed light on Kap translocation through NPCs. We investigated the effect of Kap surface charge and hydrophobicity on the transport rate. We found that the negative charge of the Kaps is essential for transport whereas Kap hydrophobicity of the transport particle aids in the translocation. Interestingly, our results indicate that the positive net charge of the nuclear Nups (especially Nup1) is instrumental for the transport of Kaps, revealing a (previously proposed) gradient of increasing binding affinity of the Kaps with FG-Nups from the cytoplasm to the nucleus.

Nuclear basket proteins Mlp1 and Nup2 drive heat shock-induced 3D genome restructuring

The nuclear pore complex (NPC), a multisubunit complex located within the nuclear envelope, regulates RNA export and the import and export of proteins. Here we address the role of the NPC in driving thermal stress-induced 3D genome repositioning of Heat Shock Responsive (HSR) genes in yeast. We found that two nuclear basket proteins, Mlp1 and Nup2, although dispensable for NPC integrity, are required for driving HSR genes into coalesced chromatin clusters, consistent with their strong, heat shock-dependent recruitment to HSR gene regulatory and coding regions. HSR gene clustering occurs predominantly within the nucleoplasm and is independent of the essential scaffold-associated proteins Nup1 and Nup145. Notably, double depletion of Mlp1 and Nup2 has little effect on the formation of Heat Shock Factor 1 (Hsf1)-containing transcriptional condensates, Hsf1 and Pol II recruitment to HSR genes, or HSR mRNA abundance. Our results define a 3D genome restructuring role for nuclear basket proteins extrinsic to the NPC and downstream of HSR gene activation.

The CDK8 kinase module: A novel player in the transcription of translation initiation and ribosomal genes

Survival following stress is dependent upon reprogramming transcription and translation. Communication between these programs following stress is critical for adaptation but is not clearly understood. The Cdk8 kinase module (CKM) of the Mediator complex modulates the transcriptional response to various stresses. Its involvement in regulating translational machinery has yet to be elucidated, highlighting an existing gap in knowledge. Here, we report that the CKM positively regulates a subset of ribosomal protein (RP) and translation initiation factor (TIF)-encoding genes under physiological conditions in Saccharomyces cerevisiae. In mouse embryonic fibroblasts and HCT116 cells, the CKM regulates unique sets of RP and TIF genes, demonstrating some conservation of function across species. In yeast, this is mediated by Cdk8 phosphorylation of one or more transcription factors which control RP and TIF expression. Conversely, the CKM is disassembled following nutrition stress, permitting repression of RP and TIF genes. The CKM also plays a transcriptional role important for promoting cell survival, particularly during translational machinery stress triggered by ribosome-targeting antibiotics. Furthermore, in mammalian cells, the activity of CDK8 and its paralogue, CDK19, promotes cell survival following ribosome inhibition. These results provide mechanistic insights into the CKM's role in regulating expression of a subset of genes associated with translation.

Alternating Cellular Functions by Optogenetic Control of Organelles

Organelles play essential roles in cellular homeostasis and various cellular functions in eukaryotic cells. The current experimental strategy to modulate organelle functions is limited due to the dynamic nature and subcellular distribution of organelles in live cells. Optogenetics utilizes photoactivatable proteins to enable dynamic control of molecular activities through visible light. This modality has been rapidly expanded for the dynamic regulation of organelle functions. This chapter describes a method by optical modulation of the mitochondria-lysosome contacts (MLCs). Detailed procedures of transfection, optogenetic MLCs, mitochondrial morphology, and functional analysis are described. Optogenetic control of organelles in live cells offers an innovative paradigm for cell engineering and synthetic biology.

Regulating transport efficiency through the nuclear pore complex: The role of binding affinity with FG-Nups

Macromolecules are transported through the nuclear pore complex (NPC) via a series of transient binding and unbinding events with FG-Nups, which are intrinsically disordered proteins anchored to the pore's inner wall. Prior studies suggest that the weak and transient nature of this binding is crucial for maintaining the transported molecules' diffusivity. In this study, we explored the relationship between binding kinetics and transport efficiency using Brownian dynamics simulations. Our results indicate that the duration of binding is a critical factor in regulating transport efficiency. Specifically, excessively short binding durations insufficiently facilitate transport, while overly long durations impede molecular movement. We calculated the optimal binding duration for efficient molecular transport and found that it aligns with other theoretical predictions. Additionally, the calculated value is comparable to experimental measurements of the association timescale between nuclear transport receptors and FG-Nups at a single binding site. Our study provides a quantitative framework that bridges local molecular interactions with overall transport dynamics through the NPC, offering valuable insights into the mechanisms governing selective molecular transport.

Systematic Evaluation and Application of IDR Domain-Mediated Transcriptional Activation of NUP98 in Saccharomyces cerevisiae

Implementing dynamic control over gene transcription to decouple cell growth is essential for regulating protein expression in microbial cells. However, the availability of efficient regulatory elements in Saccharomyces cerevisiae remains limited. In this study, we present a novel β-estradiol-inducible gene expression system, termed DEN. This system combines a DNA-binding domain with an estradiol-binding domain and an intrinsically disordered region (IDR) from NUP98. Comparative analysis shows that the DEN system outperforms IDRs from other proteins, achieving an approximately 60-fold increase in EGFP expression upon β-estradiol induction. Moreover, our system is tightly controlled; nontoxic gene expression makes it a powerful tool for rapid and precise modulation of target gene expression. This system holds great potential for unlocking new functionalities from existing proteins in future research.

C9orf72 polyPR interaction with the nuclear pore complex

The C9orf72 gene associated with amyotrophic lateral sclerosis/frontotemporal dementia is translated to five dipeptide repeat proteins, among which poly-proline-arginine (PR) is the most toxic in cell and animal models, contributing to a variety of cellular defects. It has been proposed that polyPR disrupts nucleocytoplasmic transport (NCT) through several mechanisms including accumulation in the nuclear pore complex (NPC), accumulation in the nucleolus, and direct interactions with transport receptors. The NPC, which is the key regulator of transport between the cytoplasm and nucleus, plays a central role in these suggested mechanisms. Exploring polyPR interaction with the NPC provides valuable insight into the molecular details of polyPR-mediated NCT defects. To address this, we use coarse-grained molecular dynamics models of polyPR and the yeast NPC lined with intrinsically disordered FG-nucleoporins (FG-Nups). Our findings indicate no aggregation of polyPR within the NPC or permanent binding to FG-Nups. Instead, polyPR translocates through the NPC, following a trajectory through the central low-density region of the pore. In the case of longer polyPRs, we observe a higher energy barrier for translocation and a narrower translocation channel. Our study shows that polyPR and FG-Nups are mainly engaged in steric interactions inside the NPC with only a small contribution of specific cation-pi, hydrophobic, and electrostatic interactions, allowing polyPR to overcome the entropic barrier of the NPC in a size-dependent manner.

The Potential of Nuclear Pore Complexes in Cancer Therapy

Nuclear pore complexes (NPCs) play a critical role in regulating transport-dependent gene expression, influencing various stages of cancer development and progression. Dysregulation of nucleocytoplasmic transport has profound implications, particularly in the context of cancer-associated protein mislocalization. This review provides specific information about the relationship between nuclear pore complexes, key regulatory proteins, and their impact on cancer biology. Highlighting the influence of tumor-suppressor proteins as well as the potential of gold nanoparticles and intelligent nanosystems in cancer treatment, their role in inhibiting cell invasion is examined. This article concludes with the clinical implications of nuclear export inhibitors, particularly XPO1, as a therapeutic target in various cancers, with selective inhibitors of nuclear export compounds demonstrating efficacy in both hematological and solid malignancies. The review aims to explore the role of NPCs in cancer biology, focusing on their influence on gene expression, cancer progression, protein mislocalization, and the potential of targeted therapies such as nuclear export inhibitors and intelligent nanosystems in cancer treatment. Despite their significance and the number of research studies, the direct role of NPCs in carcinogenesis remains incompletely understood.

Evolutionary trajectory for nuclear functions of ciliary transport complex proteins

SUMMARYCilia and the nucleus were two defining features of the last eukaryotic common ancestor. In early eukaryotic evolution, these structures evolved through the diversification of a common membrane-coating ancestor, the protocoatomer. While in cilia, the descendants of this protein complex evolved into parts of the intraflagellar transport complexes and BBSome, the nucleus gained its selectivity by recruiting protocoatomer-like proteins to the nuclear envelope to form the selective nuclear pore complexes. Recent studies show a growing number of proteins shared between the proteomes of the respective organelles, and it is currently unknown how ciliary transport proteins could acquire nuclear functions and vice versa. The nuclear functions of ciliary proteins are still observable today and remain relevant for the understanding of the disease mechanisms behind ciliopathies. In this work, we review the evolutionary history of cilia and nucleus and their respective defining proteins and integrate current knowledge into theories for early eukaryotic evolution. We postulate a scenario where both compartments co-evolved and that fits current models of eukaryotic evolution, explaining how ciliary proteins and nucleoporins acquired their dual functions.

Docking a flexible basket onto the core of the nuclear pore complex

The nuclear basket attaches to the nucleoplasmic side of the nuclear pore complex (NPC), coupling transcription to mRNA quality control and export. The basket expands the functional repertoire of a subset of NPCs in Saccharomyces cerevisiae by drawing a unique RNA/protein interactome. Yet, how the basket docks onto the NPC core remains unknown. By integrating AlphaFold-based interaction screens, electron microscopy and membrane-templated reconstitution, we uncovered a membrane-anchored tripartite junction between basket and NPC core. The basket subunit Nup60 harbours three adjacent short linear motifs, which connect Mlp1, a parallel homodimer consisting of coiled-coil segments interrupted by flexible hinges, and the Nup85 subunit of the Y-complex. We reconstituted the Y-complex•Nup60•Mlp1 assembly on a synthetic membrane and validated the protein interfaces in vivo. Here we explain how a short linear motif-based protein junction can substantially reshape NPC structure and function, advancing our understanding of compositional and conformational NPC heterogeneity.

Integrative spatiotemporal modeling of biomolecular processes: application to the assembly of the Nuclear Pore Complex

Dynamic processes involving biomolecules are essential for the function of the cell. Here, we introduce an integrative method for computing models of these processes based on multiple heterogeneous sources of information, including time-resolved experimental data and physical models of dynamic processes. We first compute integrative structure models at fixed time points and then optimally select and connect these snapshots into a series of trajectories that optimize the likelihood of both the snapshots and transitions between them. The method is demonstrated by application to the assembly process of the human Nuclear Pore Complex in the context of the reforming nuclear envelope during mitotic cell division, based on live-cell correlated electron tomography, bulk fluorescence correlation spectroscopy-calibrated quantitative live imaging, and a structural model of the fully-assembled Nuclear Pore Complex. Modeling of the assembly process improves the model precision over static integrative structure modeling alone. The method is applicable to a wide range of time-dependent systems in cell biology, and is available to the broader scientific community through an implementation in the open source Integrative Modeling Platform software.

Mapping the Multiscale Proteomic Organization of Cellular and Disease Phenotypes

While the primary sequences of human proteins have been cataloged for over a decade, determining how these are organized into a dynamic collection of multiprotein assemblies, with structures and functions spanning biological scales, is an ongoing venture. Systematic and data-driven analyses of these higher-order structures are emerging, facilitating the discovery and understanding of cellular phenotypes. At present, knowledge of protein localization and function has been primarily derived from manual annotation and curation in resources such as the Gene Ontology, which are biased toward richly annotated genes in the literature. Here, we envision a future powered by data-driven mapping of protein assemblies. These maps can capture and decode cellular functions through the integration of protein expression, localization, and interaction data across length scales and timescales. In this review, we focus on progress toward constructing integrated cell maps that accelerate the life sciences and translational research.

Integrative modeling meets deep learning: Recent advances in modeling protein assemblies

Recent progress in protein structure prediction based on deep learning revolutionized the field of Structural Biology. Beyond single proteins, it also enabled high-throughput prediction of structures of protein-protein interactions. Despite the success in predicting complex structures, large macromolecular assemblies still require specialized approaches. Here we describe recent advances in modeling macromolecular assemblies using integrative and hierarchical approaches. We highlight applications that predict protein-protein interactions and challenges in modeling complexes based on the interaction networks, including the prediction of complex stoichiometry and heterogeneity.

Ancient eukaryotic protein interactions illuminate modern genetic traits and disorders

All eukaryotes share a common ancestor from roughly 1.5 - 1.8 billion years ago, a single-celled, swimming microbe known as LECA, the Last Eukaryotic Common Ancestor. Nearly half of the genes in modern eukaryotes were present in LECA, and many current genetic diseases and traits stem from these ancient molecular systems. To better understand these systems, we compared genes across modern organisms and identified a core set of 10,092 shared protein-coding gene families likely present in LECA, a quarter of which are uncharacterized. We then integrated >26,000 mass spectrometry proteomics analyses from 31 species to infer how these proteins interact in higher-order complexes. The resulting interactome describes the biochemical organization of LECA, revealing both known and new assemblies. We analyzed these ancient protein interactions to find new human gene-disease relationships for bone density and congenital birth defects, demonstrating the value of ancestral protein interactions for guiding functional genetics today.

Exportin-1 functions as an adaptor for transcription factor-mediated docking of chromatin at the nuclear pore complex

Nuclear pore proteins (Nups) in yeast, flies and mammals physically interact with hundreds or thousands of chromosomal sites, which impacts transcriptional regulation. In budding yeast, transcription factors mediate interaction of Nups with enhancers of highly active genes. To define the molecular basis of this mechanism, we exploited a separation-of-function mutation in the Gcn4 transcription factor that blocks its interaction with the nuclear pore complex (NPC) without altering its DNA binding or activation domains. SILAC mass spectrometry revealed that this mutation reduces the interaction of Gcn4 with the highly conserved nuclear export factor Crm1/Xpo1. Crm1 both interacts with the same sites as Nups genome-wide and is required for Nup2 to interact with the yeast genome. In vivo, Crm1 undergoes extensive and stable interactions with the NPC. In vitro, Crm1 binds to Gcn4 and these proteins form a complex with the nuclear pore protein Nup2. Importantly, the interaction between Crm1 and Gcn4 does not require Ran-GTP, suggesting that it is not through the nuclear export sequence binding site. Finally, Crm1 stimulates DNA binding by Gcn4, supporting a model in which allosteric coupling between Crm1 binding and DNA binding permits docking of transcription factor-bound enhancers at the NPC.

Proteomics Impact on Cell Biology to Resolve Cell Structure and Function

The acceleration of advances in proteomics has enabled integration with imaging at the EM and light microscopy levels, cryo-EM of protein structures, and artificial intelligence with proteins comprehensively and accurately resolved for cell structures at nanometer to subnanometer resolution. Proteomics continues to outpace experimentally based structural imaging, but their ultimate integration is a path toward the goal of a compendium of all proteins to understand mechanistically cell structure and function.

Current Insights into the Maturation of Epstein-Barr Virus Particles

The three subfamilies of herpesviruses (alphaherpesviruses, betaherpesviruses, and gammaherpesviruses) appear to share a unique mechanism for the maturation and egress of virions, mediated by several budding and fusion processes of various organelle membranes during replication, which prevents cellular membrane disruption. Newly synthesized viral DNA is packaged into capsids within the nucleus, which are subsequently released into the cytoplasm via sequential fusion (primary envelopment) and budding through the inner and outer nuclear membranes. Maturation concludes with tegumentation and the secondary envelopment of nucleocapsids, which are mediated by budding into various cell organelles. Intracellular compartments containing mature virions are transported to the plasma membrane via host vesicular trafficking machinery, where they fuse with the plasma membrane to extracellularly release mature virions. The entire process of viral maturation is orchestrated by sequential interactions between viral proteins and intracellular membranes. Compared with other herpesvirus subfamilies, the mechanisms of gammaherpesvirus maturation and egress remain poorly understood. This review summarizes the major findings, including recently updated information of the molecular mechanism underlying the maturation and egress process of the Epstein-Barr virus, a ubiquitous human gammaherpesvirus subfamily member that infects most of the population worldwide and is associated with a number of human malignancies.

Nucleoporin93 limits Yap activity to prevent endothelial cell senescence

As the innermost lining of the vasculature, endothelial cells (ECs) are constantly subjected to systemic inflammation and particularly vulnerable to aging. Endothelial health is hence vital to prevent age-related vascular disease. Healthy ECs rely on the proper localization of transcription factors via nuclear pore complexes (NPCs) to govern cellular behavior. Emerging studies report NPC degradation with natural aging, suggesting impaired nucleocytoplasmic transport in age-associated EC dysfunction. We herein identify nucleoporin93 (Nup93), a crucial structural NPC protein, as an indispensable player in vascular protection. Endothelial Nup93 protein levels are significantly reduced in the vasculature of aged mice, paralleling observations of Nup93 loss when using in vitro models of EC senescence. The loss of Nup93 in human ECs induces cell senescence and promotes the expression of inflammatory adhesion molecules, where restoring Nup93 protein in senescent ECs reverses features of endothelial aging. Mechanistically, we find that both senescence and loss of Nup93 impair endothelial NPC transport, leading to nuclear accumulation of Yap and downstream inflammation. Pharmacological studies indicate Yap hyperactivation as the primary consequence of senescence and Nup93 loss in ECs. Collectively, our findings indicate that the maintenance of endothelial Nup93 is a key determinant of EC health, where aging targets endothelial Nup93 levels to impair NPC function as a novel mechanism of EC senescence and vascular aging.

Nuclear pore complex proteins are involved in centromere distribution

The subnuclear distribution of centromeres is cooperatively regulated by condensin II and the linker of nucleoskeleton and cytoskeleton (LINC) complex. However, other nuclear membrane structures and nuclear proteins are probably involved in centromere dynamics and distribution. Here, we focused on the nuclear pore complex (NPC), which is known to regulate gene expression, transcription memory, and chromatin structure in addition to transport between the cytoplasm and nucleoplasm. We report here that some nucleoporins (Nups), including Nup85, Nup133, CG1, Nup93b, and NUA, are involved in centromere scattering in Arabidopsis thaliana. In addition, the centromere dynamics after metaphase in nup mutants were found to be similar to that of the condensin II mutant. Furthermore, both biochemical and genetic approaches showed that the Nups interact with the LINC complex. These results suggest that Nups regulate centromere scattering cooperatively with condensin II and the LINC complex.

Bonds and bytes: The odyssey of structural biology

Characterizing structural and dynamic properties of proteins and large macromolecular assemblies is crucial to understand the molecular mechanisms underlying biological functions. In the field of structural biology, no single method comprehensively reveals the behavior of biological systems across various spatiotemporal scales. Instead, we have a versatile toolkit of techniques, each contributing a piece to the overall puzzle. Integrative structural biology combines different techniques to create accurate and precise multi-scale models that expand our understanding of complex biological systems. This review outlines recent advancements in computational and experimental methods in structural biology, with special focus on recent Artificial Intelligence techniques, emphasizes integrative approaches that combine different types of data for precise spatiotemporal modeling, and provides an outlook into future directions of this field.

Nucleoporin 50 proteins affect longevity and salinity stress tolerance in seeds

Nucleoporin 50 (Nup50) is an evolutionarily conserved protein that is a constituent of the nuclear pore complex (NPC); however, its physiological role in plants is unclear. Arabidopsis has two Nup50 proteins, Nup50a and Nup50b, which are highly expressed in developing seeds. Green fluoresceent protein (GFP)-fused Nup50a and Nup50b are localized exclusively in the nucleopolasm, implying an additional function beyond the NPC in the nuclear envelope. To investigate the function of Nup50s, we employed the CRISPR/Cas9 [clustered regularly interspaced palindromic repeats (CRISPR)/CRISPR-associated protein 9] system to generate a nup50a nup50b double mutant, which exhibited premature translation termination of both Nup50 proteins. While the mutant showed no significant abnormal phenotype during vegetative growth, the nup50a nup50b seeds had an abnormal shape compared with the wild type. Comparative transcriptomics using immature seeds revealed that Nup50s regulate the expression of various genes, including cell wall-related genes. The nup50a nup50b seeds exhibited reduced seed longevity and salinity stress tolerance. Tetrazolium uptake and mucilage release assays implied that the nup50a nup50b seeds had greater water permeability than the wild type. Taken together, our results imply that Nup50s play a critical role in seed formation by regulating gene expression.

Integrative Approaches to Study Virus Structures

A virus particle must work as a strongroom to protect its genome, but at the same time it must undergo dramatic conformational changes to infect the cell in order to replicate and assemble progeny. Thus, viruses are miniaturized wonders whose structural complexity requires investigation by a combination of different techniques that can tackle both static and dynamic processes. In this chapter, we will illustrate how major structural techniques such as X-ray crystallography and electron microscopy can be combined with other techniques to determine the structure of complex viruses. The power of these hybrid approaches is discussed through a number of examples.

Epigenetics

Epigenetics is the study of heritable changes to the genome and gene expression patterns that are not caused by direct changes to the DNA sequence. Examples of these changes include posttranslational modifications to DNA-bound histone proteins, DNA methylation, and remodeling of nuclear architecture. Collectively, epigenetic changes provide a layer of regulation that affects transcriptional activity of genes while leaving DNA sequences unaltered. Sequence variants or mutations affecting enzymes responsible for modifying or sensing epigenetic marks have been identified in patients with congenital heart disease (CHD), and small-molecule inhibitors of epigenetic complexes have shown promise as therapies for adult heart diseases. Additionally, transgenic mice harboring mutations or deletions of genes encoding epigenetic enzymes recapitulate aspects of human cardiac disease. Taken together, these findings suggest that the evolving field of epigenetics will inform our understanding of congenital and adult cardiac disease and offer new therapeutic opportunities.

Picornavirus 3C Proteins Intervene in Host Cell Processes through Proteolysis and Interactions with RNA

The Picornaviridae family comprises a large group of non-enveloped viruses with enormous impact on human and animal health. The picornaviral genome contains one open reading frame encoding a single polyprotein that can be processed by viral proteases. The picornaviral 3C proteases share similar three-dimensional structures and play a significant role in the viral life cycle and virus-host interactions. Picornaviral 3C proteins also have conserved RNA-binding activities that contribute to the assembly of the viral RNA replication complex. The 3C protease is important for regulating the host cell response through the cleavage of critical host cell proteins, acting to selectively 'hijack' host factors involved in gene expression, promoting picornavirus replication, and inactivating key factors in innate immunity signaling pathways. The protease and RNA-binding activities of 3C are involved in viral polyprotein processing and the initiation of viral RNA synthesis. Most importantly, 3C modifies critical molecules in host organelles and maintains virus infection by subtly subverting host cell death through the blocking of transcription, translation, and nucleocytoplasmic trafficking to modulate cell physiology for viral replication. Here, we discuss the molecular mechanisms through which 3C mediates physiological processes involved in promoting virus infection, replication, and release.

Single-Cell Plasmonic Immunosandwich Assay Reveals the Modulation of Nucleocytoplasmic Localization Fluctuation of ABL1 on Cell Migration

Cell migration is an essential process of cancer metastasis. The spatiotemporal dynamics of signaling molecules influences cellular phenotypic outcomes. It has been increasingly documented that the Abelson (ABL) family kinases play critical roles in solid tumors. However, ABL1's shuttling dynamics in cell migration still remains unexplored. This is mainly because tools permitting the investigation of translocation dynamics of proteins in single living cells are lacking. Herein, to bridge this gap, we developed a unique multifunctional integrated single-cell analysis method that enables long-term observation of cell migration behavior and monitoring of signaling proteins and complexes at the subcellular level. We found that the shuttling of ABL1's to the cytoplasm results in a higher migration speed, while its trafficking back to the nucleus leads to a lower one. Furthermore, our results indicated that fluctuant protein-protein interactions between 14-3-3 and ABL1 modulate ABL1's nucleocytoplasmic fluctuation and eventually affect the cell speed. Importantly, based on these new insights, we demonstrated that disturbing ABL1's nuclear export traffic and 14-3-3-ABL1 complexes formation can effectively suppress cell migration. Thus, our method opens up a new possibility for simultaneous tracking of internal molecular mechanisms and cell behavior, providing a promising tool for the in-depth study of cancer.

The scaffold nucleoporins SAR1 and SAR3 are essential for proper meiotic progression in Arabidopsis thaliana

Nuclear Pore Complexes (NPCs) are embedded in the nuclear envelope (NE), regulating macromolecule transport and physically interacting with chromatin. The NE undergoes dramatic breakdown and reformation during plant cell division. In addition, this structure has a specific meiotic function, anchoring and positioning telomeres to facilitate the pairing of homologous chromosomes. To elucidate a possible function of the structural components of the NPCs in meiosis, we have characterized several Arabidopsis lines with mutations in genes encoding nucleoporins belonging to the outer ring complex. Plants defective for either SUPPRESSOR OF AUXIN RESISTANCE1 (SAR1, also called NUP160) or SAR3 (NUP96) present condensation abnormalities and SPO11-dependent chromosome fragmentation in a fraction of meiocytes, which is increased in the double mutant sar1 sar3. We also observed these meiotic defects in mutants deficient in the outer ring complex protein HOS1, but not in mutants affected in other components of this complex. Furthermore, our findings may suggest defects in the structure of NPCs in sar1 and a potential link between the meiotic role of this nucleoporin and a component of the RUBylation pathway. These results provide the first insights in plants into the role of nucleoporins in meiotic chromosome behavior.

Nucleoporin93 (Nup93) Limits Yap Activity to Prevent Endothelial Cell Senescence

Endothelial cells (ECs) form the innermost lining of the vasculature and serve a pivotal role in preventing age-related vascular disease. Endothelial health relies on the proper nucleocytoplasmic shuttling of transcription factors via nuclear pore complexes (NPCs). Emerging studies report NPC degradation with natural aging, suggesting impaired nucleocytoplasmic transport in age-related EC dysfunction. We herein identify nucleoporin93 (Nup93), a crucial structural NPC protein, as an indispensable player for vascular protection. Endothelial Nup93 protein levels are significantly reduced in the vasculature of aged mice, paralleling observations of Nup93 loss when using in vitro models of endothelial aging. Mechanistically, we find that loss of Nup93 impairs NPC transport, leading to the nuclear accumulation of Yap and downstream inflammation. Collectively, our findings indicate maintenance of endothelial Nup93 as a key determinant of EC health, where aging targets endothelial Nup93 levels to impair NPC function as a novel mechanism for EC senescence and vascular aging.

Nuclear transport proteins: structure, function, and disease relevance

Proper subcellular localization is crucial for the functioning of biomacromolecules, including proteins and RNAs. Nuclear transport is a fundamental cellular process that regulates the localization of many macromolecules within the nuclear or cytoplasmic compartments. In humans, approximately 60 proteins are involved in nuclear transport, including nucleoporins that form membrane-embedded nuclear pore complexes, karyopherins that transport cargoes through these complexes, and Ran system proteins that ensure directed and rapid transport. Many of these nuclear transport proteins play additional and essential roles in mitosis, biomolecular condensation, and gene transcription. Dysregulation of nuclear transport is linked to major human diseases such as cancer, neurodegenerative diseases, and viral infections. Selinexor (KPT-330), an inhibitor targeting the nuclear export factor XPO1 (also known as CRM1), was approved in 2019 to treat two types of blood cancers, and dozens of clinical trials of are ongoing. This review summarizes approximately three decades of research data in this field but focuses on the structure and function of individual nuclear transport proteins from recent studies, providing a cutting-edge and holistic view on the role of nuclear transport proteins in health and disease. In-depth knowledge of this rapidly evolving field has the potential to bring new insights into fundamental biology, pathogenic mechanisms, and therapeutic approaches.

Puzzling out nuclear pore complex assembly

Nuclear pore complexes (NPCs) are sophisticated multiprotein assemblies embedded within the nuclear envelope and controlling the exchanges of molecules between the cytoplasm and the nucleus. In this review, we summarize the mechanisms by which these elaborate complexes are built from their subunits, the nucleoporins, based on our ever-growing knowledge of NPC structural organization and on the recent identification of additional features of this process. We present the constraints faced during the production of nucleoporins, their gathering into oligomeric complexes, and the formation of NPCs within nuclear envelopes, and review the cellular strategies at play, from co-translational assembly to the enrolment of a panel of cofactors. Remarkably, the study of NPCs can inform our perception of the biogenesis of multiprotein complexes in general - and vice versa.

Nuclear pore complex and nucleocytoplasmic transport disruption in neurodegeneration

Nuclear pore complexes (NPCs) play a critical role in maintaining the equilibrium between the nucleus and cytoplasm, enabling bidirectional transport across the nuclear envelope, and are essential for proper nuclear organization and gene regulation. Perturbations in the regulatory mechanisms governing NPCs and nuclear envelope homeostasis have been implicated in the pathogenesis of several neurodegenerative diseases. The ESCRT-III pathway emerges as a critical player in the surveillance and preservation of well-assembled, functional NPCs, as well as nuclear envelope sealing. Recent studies have provided insights into the involvement of nuclear ESCRT-III in the selective reduction of specific nucleoporins associated with neurodegenerative pathologies. Thus, maintaining quality control of the nuclear envelope and NPCs represents a pivotal element in the pathological cascade leading to neurodegenerative diseases. This review describes the constituents of the nuclear-cytoplasmic transport machinery, encompassing the nuclear envelope, NPC, and ESCRT proteins, and how their structural and functional alterations contribute to the development of neurodegenerative diseases.

Implications of a multiscale structure of the yeast nuclear pore complex

Nuclear pore complexes (NPCs) direct the nucleocytoplasmic transport of macromolecules. Here, we provide a composite multiscale structure of the yeast NPC, based on improved 3D density maps from cryogenic electron microscopy and AlphaFold2 models. Key features of the inner and outer rings were integrated into a comprehensive model. We resolved flexible connectors that tie together the core scaffold, along with equatorial transmembrane complexes and a lumenal ring that anchor this channel within the pore membrane. The organization of the nuclear double outer ring reveals an architecture that may be shared with ancestral NPCs. Additional connections between the core scaffold and the central transporter suggest that under certain conditions, a degree of local organization is present at the periphery of the transport machinery. These connectors may couple conformational changes in the scaffold to the central transporter to modulate transport. Collectively, this analysis provides insights into assembly, transport, and NPC evolution.

Nuclear pore complexes mediate subtelomeric gene silencing by regulating PCNA levels on chromatin

The nuclear pore complex (NPC) physically interacts with chromatin and regulates gene expression. The Saccharomyces cerevisiae inner ring nucleoporin Nup170 has been implicated in chromatin organization and the maintenance of gene silencing in subtelomeric regions. To gain insight into how Nup170 regulates this process, we used protein-protein interactions, genetic interactions, and transcriptome correlation analyses to identify the Ctf18-RFC complex, an alternative proliferating cell nuclear antigen (PCNA) loader, as a facilitator of the gene regulatory functions of Nup170. The Ctf18-RFC complex is recruited to a subpopulation of NPCs that lack the nuclear basket proteins Mlp1 and Mlp2. In the absence of Nup170, PCNA levels on DNA are reduced, resulting in the loss of silencing of subtelomeric genes. Increasing PCNA levels on DNA by removing Elg1, which is required for PCNA unloading, rescues subtelomeric silencing defects in nup170Δ. The NPC, therefore, mediates subtelomeric gene silencing by regulating PCNA levels on DNA.

The nuclear pore complex as a platform for epigenetic regulation

The nuclear pore complex (NPC) both mediates exchange of proteins and RNA between the nucleus and the cytoplasm and physically interacts with chromatin to regulate transcription. In this issue of JCB, Kumar et al. (2023. J. Cell Biol.https://doi.org/10.1083/jcb.202207060) provide new insight into the molecular basis for NPC-mediated epigenetic silencing through loading of the replication processivity factor PCNA.

SUMOylation at the inner nuclear membrane facilitates nuclear envelope biogenesis during mitosis

As eukaryotic cells progress through cell division, the nuclear envelope (NE) membrane must expand to accommodate the formation of progeny nuclei. In Saccharomyces cerevisiae, closed mitosis allows visualization of NE biogenesis during mitosis. During this period, the SUMO E3 ligase Siz2 binds the inner nuclear membrane (INM) and initiates a wave of INM protein SUMOylation. Here, we show these events increase INM levels of phosphatidic acid (PA), an intermediate of phospholipid biogenesis, and are necessary for normal mitotic NE membrane expansion. The increase in INM PA is driven by the Siz2-mediated inhibition of the PA phosphatase Pah1. During mitosis, this results from the binding of Siz2 to the INM and dissociation of Spo7 and Nem1, a complex required for the activation of Pah1. As cells enter interphase, the process is then reversed by the deSUMOylase Ulp1. This work further establishes a central role for temporally controlled INM SUMOylation in coordinating processes, including membrane expansion, that regulate NE biogenesis during mitosis.

Subcellular visualization: Organelle-specific targeted drug delivery and discovery

Organelles perform critical biological functions due to their distinct molecular composition and internal environment. Disorders in organelles or their interacting networks have been linked to the incidence of numerous diseases, and the research of pharmacological actions at the organelle level has sparked pharmacists' interest. Currently, cell imaging has evolved into a critical tool for drug delivery, drug discovery, and pharmacological research. The introduction of advanced imaging techniques in recent years has provided researchers with richer biological information for viewing and studying the ultrastructure of organelles, protein interactions, and gene transcription activities, leading to the design and delivery of precision-targeted drugs. Therefore, this reviews the research on organelles-targeted drugs based upon imaging technologies and development of fluorescent molecules for medicinal purposes. We also give a thorough analysis of a number of subcellular-level elements of drug development, including subcellular research instruments and methods, organelle biological event investigation, subcellular target and drug identification, and design of subcellular delivery systems. This review will make it possible to promote drug research from the individual/cellular level to the subcellular level, as well as give a new focus based on newly found organelle activities.

SCARB1 downregulation in adrenal insufficiency with Allgrove syndrome

BACKGROUND

Allgrove disease is a rare genetic syndrome characterized by adrenal insufficiency, alacrimia, achalasia and complex neurological involvement. Allgrove disease is due to recessive mutations in the AAAS gene, which encodes for the nucleoporin Aladin, implicated in the nucleocytoplasmic transport. The adrenal insufficiency has been suggested to rely on adrenal gland-ACTH resistance. However, the link between the molecular pathology affecting the nucleoporin Aladin and the glucocorticoid deficiency is still unknown.

RESULTS

By analyzing postmortem patient's adrenal gland, we identified a downregulation of Aladin transcript and protein. We found a downregulation of Scavenger receptor class B-1 (SCARB1), a key component of the steroidogenic pathway, and SCARB1 regulatory miRNAs (mir125a, mir455) in patient's tissues. With the hypothesis of an impairment in the nucleocytoplasmic transport of the SCARB1 transcription enhancer cyclic AMP-dependent protein kinase (PKA), we detected a reduction of nuclear Phospho-PKA and a cytoplasmic mislocalization in patient's samples.

CONCLUSIONS

These results shed a light on the possible mechanisms linking ACTH resistance, SCARB1 impairment, and defective nucleocytoplasmic transport.