SIRT6, a highly conserved member of the sirtuin family, plays a critical role in diverse cellular processes, including gene regulation, DNA damage response and maintaining nuclear lamina integrity. These functions are essential in contexts such as differentiation, metabolic regulation, cancer development and ageing. Given the multifaceted influence of SIRT6 on cellular activities, there is an increasing interest in elucidating the regulatory mechanisms governing its enzymatic functions. SIRT6 exhibits two NAD+-dependent activities: deacetylation and ADP-ribosylation, with current research predominantly focusing on the former. However, the latter-its (ADP-ribosyl)transferase activity-remains underexplored, particularly concerning the specific amino acid targets it modifies and the (ADP-ribosyl)hydrolases that can reverse these modifications. In this study, we have utilized biochemical assays and proteomic techniques to investigate these aspects, revealing that SIRT6 transfers ADP-ribosyl moieties onto histidine and tyrosine residues. In addition, we reveal that the (ADP-ribosyl)hydrolase ARH3 has significant activity in erasing SIRT6-derived ADP-ribosylation in cells.

Craniomaxillofacial bone marrow mesenchymal stromal cells (BMSCs) retaining neural crest-derived neurogenic niche is driven by lineage memory and niche homeostasis. Elucidating how the neurogenic potential is maintained is critical for neurological health. Here, we explored a neural crest-like progenitor niche in BMSCs with high neurogenic and proliferative capacity by single-cell transcriptomics. In which, ANKRD1 is a pivotal regulator sustaining the neurogenic reservoir. Importantly, ANKRD1 expression in this niche declines with aging and lineage commitment, coinciding with its redistribution from a diffuse nucleoplasmic pattern to perinuclear enrichment along the nuclear lamina and loss of neural potential. Mechanistically, ANKRD1 preserves neurogenic capacity by directly binding super-enhancers of neural marker genes (SOX2, NESTIN) and maintaining open chromatin architecture. Critically, neuron-targeted ANKRD1 delivery rescues spatial memory deficits in aged mice. These findings establish ANKRD1 as a therapeutically tractable regulator that sustains neurogenic chromatin reservoirs to support neurocognitive resilience, opening avenues to counter cognitive aging.

Hypoxia is a physiologically relevant microenvironment in both normal and diseased tissues and has emerged as a potent modulator of cellular senescence and organismal longevity. This review synthesizes evidence that hypoxia delays senescence across diverse experimental systems and species, and highlights mechanisms by which hypoxia rewires chromatin states during senescence-associated transitions. We focus on oxygen- and α-ketoglutarate-dependent epigenetic regulators, particularly histone lysine demethylases, whose catalytic activities are limited under hypoxia. Consequently, histone methylation increases and higher-order chromatin organization is stabilized. Using oncogene-induced senescence as an experimentally tractable framework, we discuss recent findings showing that hypoxia suppresses senescence-associated histone clipping, preserves nuclear lamina integrity, and restrains large-scale heterochromatin reorganization while leaving canonical cell-cycle arrest largely intact. We further consider emerging links among DNA damage, epigenetic instability, and aging phenotypes, and propose that senescence can be viewed as a breakdown of coordinated epigenetic homeostasis. By integrating these concepts, we position hypoxia and hypoxia-mimetic interventions as promising strategies to modulate aging-associated cellular states and to explore therapeutic opportunities in age-related pathologies.

The nuclear lamina is disassembled during mitosis, and certain DNA viruses exploit this process to facilitate replication. While we previously showed that baculoviruses disrupt the exogenously integrated lamina, their impact on the endogenous structure, the underlying mechanism, and the functional consequences for viral replication remained unknown. Here, we demonstrate that baculovirus infection triggers endogenous nuclear lamina disassembly, and that phosphorylation of lamin B at the N-terminal "mitotic site" serine 47 (S47) is the key event driving this process. Using in vitro phosphorylation assays, phospho-specific reagents, and site-directed mutagenesis, we further show that baculoviruses exploit the mitotic kinase cyclin-dependent kinase 1 (CDK1) to directly phosphorylate S47, thereby disrupting the lamina. Critically, this baculovirus-induced lamina disruption is not an epiphenomenon; transmission electron microscopy and viral titer assays demonstrate it is essential for the efficient nuclear egress of nucleocapsids and the production of infectious budded virions. Our study thus defines a distinct mechanism of viral subversion, wherein a virus directly repurposes the core mitotic machinery to breach the nuclear lamina barrier, a finding that significantly advances our understanding of host‒pathogen conflict.

IntroductionHutchinson-Gilford Progeria Syndrome (HGPS) is a fatal, accelerated-aging disease caused by a mutation in the nuclear envelope protein Lamin A. The resulting mutant protein, progerin, accumulates on the nuclear envelope, causing nuclear blebbing, altered gene expression, and other cellular defects. The primary pathology of HGPS is atherosclerosis, leading to stroke or heart attack. Given that atherosclerosis generally begins with endothelial dysfunction, we examined whether the HGPS endothelium has an altered genetic response to shear stress, contributing to atherogenesis.MethodsWe exposed HGPS and healthy iPSC-derived endothelial cells (viECs) to steady laminar shear stress at 12 dyn/cm2 in a parallel-plate flow chamber. We examined morphology changes, differential gene expression (DE) via RNA-seq, and Gene Set Enrichment Analysis (GSEA) after 24 h.ResultsElongation after flow is impaired in HGPS viECs compared with healthy viECs. DE analysis showed fewer significant DE genes and a lower magnitude of gene expression change after flow in HGPS compared with healthy viECs. GSEA identified differences in the gene sets altered by flow-induced DE, including Cholesterol Homeostasis, which was overrepresented in HGPS viECs. LGALS3, encoding the atherosclerosis marker galectin-3, was a main driver of this overrepresentation. RT-PCR confirmed LGALS3 is robustly upregulated in HGPS viECs compared with healthy viECs after flow. Treatment with an adenine base editor correcting the HGPS mutation restored LGALS3 expression to healthy levels.ConclusionThese observations indicate that HGPS ECs have an aberrant molecular response to atheroprotective shear stress, including impaired elongation and upregulation of the pro-inflammatory gene LGALS3, which contributes to atherogenesis in HGPS patients.

Nuclear envelope stretch and rupture are common to cell spreading and migration in a variety of microenvironments, leading to marked changes in nucleocytoplasmic transport. Predicting cell response to different mechanochemical cues that are transmitted to the nucleus remains an open problem in the field of mechanomedicine. We developed a predictive modeling framework to examine how nuclear deformation on substrates with different nanotopographies influences nucleocytoplasmic transport and rearrangement of the nuclear lamina. Using the finite element method, we simulated nuclear compression by the perinuclear actin cap on substrates with arrays of nanopillars, modeling the nuclear envelope as a nonlinear elastic structure and coupling deformations to a biochemical model of lamin remodeling and nucleocytoplasmic transport. These simulations predicted regions of high nuclear envelope stretch adjacent to cell-nanopillar contacts, leading to maximized laminar stress on small nanopillars spaced by 4-5 microns. We then considered the effects on nuclear transport of YAP and TAZ and found that increased nuclear compression led to YAP/TAZ nuclear localization in agreement with previous experiments. Furthermore, the simulated force load per lamin was maximized on nanopillar substrates with high nuclear stretch. The magnitude of this load was modulated by the rate of actin cap assembly and the overall expression level of lamin A/C – decreasing lamin content in the nuclear envelope led to a higher likelihood of rupture. We validated this prediction in subsequent experiments with lamin-depleted U2OS cells, establishing the central importance of lamin transport and microenvironment nanotopography to nuclear mechanotransduction.

Mutations in LMNA, encoding nuclear lamina protein Lamin A/C, cause premature aging disorders, most notably Hutchinson-Gilford Progeria Syndrome. Despite obvious skull abnormalities in progeroid patients, the disease-causing mechanism remains elusive. The L648R single amino acid substitution blocks prelamin A maturation in mice, modeling a unique human patient. Here, we describe skull deformities in premature aging caused by aberrant suture fusion resembling those of patients with craniosynostosis. Further examinations identify prelamin A accumulation causatively linked to multiple suture synostoses in low bone density. This etiology is distinct from conventional suture fusion mediated by excessive ossification. In addition, the mutation disrupts skeletal stem cell stemness and subsequent stem cell-mediated proliferation and differentiation in osteogenesis. Intrasutural bones present in progeroid patients are highly reminiscent of synostosis caused by stem cell exhaustion. Comparative gene expression profiling further reveals cytoskeletal dynamics associated with skeletogenic cell aging and suture patency in mice and humans. Functional studies demonstrate that abnormal structures of progeric nuclei caused by prelamin A accumulation affect cytoskeleton organization and nucleoskeleton assembly essential for craniofacial skeletogenesis. Pharmacogenetic analyses indicate alleviation of osteogenic defects via actin polymerization. Our findings provide compelling evidence for nuclear and cytoskeletal defects, mediating stem cell-associated osteogenic deformities in progeroid disorders.

A role for long-lived nuclear envelope proteins in cardiac ageing.

Cell swelling has been reported in physiological tumor contexts, but whether sustained cell volume expansion leaves a durable state that reshapes drug and immune responses in melanoma is unknown. Using controlled hypotonic dilution as an experimental handle, we compare two priming regimens with comparable hypotonic exposure but different magnitude and persistence of volume expansion, enabling us to test which post-recovery phenotypes track with sustained enlargement beyond hypotonic exposure alone. Sustained enlargement produces a measurable size imprint after return to isotonic conditions, accompanied by nuclear lamina and chromatin remodeling with p53 pathway engagement and suppression of replication and growth programs. After recovery, primed cells reinforce F-actin organization, migrate faster in 3D collagen, and induce antioxidant and anti-ferroptosis defenses consistent with improved stress survival. A gene expression signature derived from this response is associated with poorer outcome in TCGA skin cutaneous melanoma. Unexpectedly, the same volume history also increases IFN-γ response, elevates MHC-I, reduces sialylation, and increases susceptibility to CD8+ T cell killing. These findings indicate that persistent volume history can couple drug tolerance programs to an exploitable increase in immune visibility.

Spatiotemporal changes in the nuclear lamina and cell metabolism shape cell fate, yet their interplay is poorly understood. Here we identify lamin A/C as a key regulator of cysteine catabolic flux essential for proper cell fate and longevity. Its loss in naive mouse pluripotent stem cells leads to upregulation of the cysteine-generating and catabolizing enzymes, cystathionine γ-lyase (CTH) and cystathionine β-synthase (CBS), thereby promoting de novo cysteine synthesis. Increased cysteine flux into acetyl-CoA fosters histone H3K9 and H3K27 acetylation, triggering a transition from naive to primed pluripotency and abnormal cell fate and function. Conversely, the toxic gain-of-function mutation of Lmna, encoding lamin A/C and associated with premature ageing, reduces CTH and CBS levels. This reroutes cysteine catabolic flux and alters the balance between H3K9 acetylation and methylation, crucially impacting germ layer formation and genome stability. Notably, modulation of Cth and Cbs rescues the abnormal cell fate and function, restores the DNA damage repair capacity and alleviates the senescent phenotype caused by lamin A/C mutations, highlighting the potential of modulating cell metabolism to mitigate epigenetic diseases.

The nucleus, as the largest organelle within the cell, serves as the central hub for storing, replicating, and transcribing genetic information, thereby orchestrating vital cellular processes. In eukaryotic cells, the nuclear membrane is composed of several structural components: the outer and inner nuclear membranes, the nuclear pore complexes, and the underlying nuclear lamina, which together preserve the stability of the intracellular environment. Neurodegenerative disorders, such as Alzheimer's disease and related dementias, are characterized by the gradual degeneration and loss of neuronal structure and function in the central nervous system. Growing evidence suggests that alterations in nuclear envelope architecture are closely associated with the onset and progression of these diseases. This article summarizes the information, focusing on the regulators of the cell nuclear membrane, as well as its pathophysiological processes and regulatory mechanisms in neurodegenerative diseases. Moreover, this paper discusses related research advances that provide novel insights into a deeper understanding of the nuclear membrane in disease progression and its potential as a therapeutic target.

Meiotic drive is a phenomenon that violates Mendel's Law of Equal Segregation, leading to biased transmission of the meiotic driver to the offspring. D. melanogaster Stellate (Ste) is an X-linked meiotic driver that preferentially harms Y-chromosome-bearing spermatids, thereby favoring the transmission of the X chromosome to the next generation. We have recently shown that Ste protein segregates asymmetrically during meiosis I with a strong bias toward the Y-chromosome-inheriting side, leading to the eventual demise of the Y-chromosome-containing spermatids. However, the cellular mechanisms by which Ste protein interferes with spermatid development remain unknown. Here, we show that Ste-containing spermatids are delayed in the process of nuclear envelope remodeling, an essential process during sperm DNA compaction. We show that components of the nuclear lamina (such as Lamin Dm0, and the LEM domain proteins Otefin and Bocks) are rapidly removed during nuclear envelope remodeling during the early stages of normal spermatid development. However, Ste-containing spermatids retained these nuclear lamina proteins for a prolonged time. Their delayed removal is associated with defective formation of the dense complex, which is composed of a bundle of microtubules and serves as a structural support for sperm nuclear morphogenesis. Defective dense complex formation in Ste-containing spermatids led to defective sperm DNA compaction. Together, the present study reveals an unexpected cellular mechanism by which a meiotic driver, Ste, sabotages sperm development.

ABSTRACTRegulation of lamin A/C levels and distribution is crucial for nuclear integrity and mechanotransduction via the linker of nucleoskeleton and cytoskeleton (LINC) complex. Dysregulation of lamin A/C correlates with poor cancer prognosis, and its levels determine sensitivity to the microtubule-stabilising drug paclitaxel. Paclitaxel is well-known for disrupting mitosis, yet it also reduces tumour size in slow-dividing tumours, indicating an additional, poorly characterised interphase mechanism. Here, we reveal that paclitaxel induces nuclear aberrations in interphase through SUN2-dependent lamin A/C disruption. Using advanced optical imaging and electron cryo-tomography, we show the formation of aberrant microtubule–vimentin bundles during paclitaxel treatment, which coincides with nuclear deformation and altered lamin A/C protein levels and organisation at the nuclear envelope. SUN2 is required for lamin A/C reduction upon paclitaxel treatment and is in turn regulated by polyubiquitylation. Furthermore, lamin A/C expression levels determine not only cell survival during treatment but also recovery after drug removal. Our findings support a model in which paclitaxel acts through both defective mitosis and interphase nuclear–cytoskeletal disruption, providing additional mechanistic insights into a widely used anticancer drug.

Nuclear mechanics is remodeled not only by extracellular forces but also by internal modifications, such as those induced by viral infections. During herpes simplex virus type 1 infection, the nuclear structures undergo drastic reorganization, but little is known about how nuclear mechanobiology changes as a result. We show that the nucleus softens dramatically during the infection. To understand the phenomenon, we used advanced microscopy and computational modeling. We discovered that the enlarged viral replication compartment had a low biomolecular density, partially explaining the observed nuclear softening. The mobility of the nuclear lamina decreased, which suggests increased rigidity and an inability to induce softening. However, computational modeling supported by experimental data showed that reduced outward forces, such as cytoskeletal pull and intranuclear osmotic pressure acting both on and within the nucleus, can explain the decreased nuclear stiffness. Our findings reveal that during infection, the nucleus is subject to changes in multiple mechanical forces, leading to decreased nuclear stiffness.

Vesicle-associated membrane protein-associated protein A (VAPA) is a protein of the endoplasmic reticulum (ER) and a component of several membrane contact sites (MCSs). We show here that VAPA also localizes to the inner nuclear membrane (INM), in close proximity to nuclear lamins, INM proteins and nucleoporins. Using our proteomics approach 'rapamycin- and APEX-dependent identification of proteins by SILAC' (RAPIDS), we identified several nuclear proximity partners of VAPA, including emerin, different LAP2 isoforms, lamin A/C and Nup153. Depletion of VAPA in various cellular systems resulted in reduced nuclear lamin levels and aberrant nuclear morphology, including the formation of membrane invaginations and tunnels. Furthermore, histone acetylation levels were altered. Our data suggest that VAPA has distinct nuclear functions, in addition to its established role as an ER organizer.

Localization of the actin-, lipid- and mRNA-binding protein Annexin A2 (AnxA2) in dividing cells revealed its presence in large spherical structures which are confined to the cell periphery and frequently co-align with astral microtubules. These structures appear during prometaphase and disappear at telophase, coinciding with the mitotic breakdown and subsequent reformation of the nuclear lamina and envelope. Their size increases as cells progress to anaphase, while their number decreases, suggesting that they are capable of fusion. Treatment of cells with the aliphatic alcohol propylene glycol led to rapid and reversible disassembly of the structures, providing further evidence that they correspond to biomolecular condensates. Notably, the condensates enclose compartments involved in biosynthetic or endocytic membrane recycling – defined by Rab1, Rab11, or endocytosed transferrin–but lack other membrane organelles, indicating that they may serve as mitotic reservoirs for selected endomembranes. Additionally, the condensates incorporate lamin B, which connects with the pericentrosomal membrane recycling compartments during prometaphase, when the nuclear lamina disassembles in conjunction with centrosome separation. These findings show similarities between the peripheral mitotic condensates and the membranous lamin B spindle matrix which has been proposed to act in spindle organization and organelle inheritance. The separating daughter cells at late anaphase contain equal numbers of the condensates, in accordance with their potential role in mitotic partitioning of endomembranes and other cytoplasmic components.

ABSTRACTLamin A/C is a crucial structural component of the nuclear lamina that influences chromatin organization and gene regulation. In this study, we demonstrate that lamin A/C is vital for maintaining higher-order genome organization and transcriptional programs that support EBV-driven B-cell activation. Loss of lamin A/C in a B-lymphoblastoid cell line caused significant three-dimensional reorganization of the genome, evidenced by the loss of long-range chromatin loops, an increase in short-range contacts, and redistribution of H3K9me2- marked heterochromatin. These structural disruptions were linked to widespread changes in gene expression affecting metabolic, signaling, and differentiation pathways. Mechanistically, lamin A/C influences the nuclear positioning and transcription of CTCF-bound loci by preventing their relocation to the periphery and their association with lamin B1. Blocking H3K9me2 deposition mimicked the transcriptional effects of lamin A/C depletion and revealed increased sensitivity to PI3K inhibitors. Overall, our results identify lamin A/C as a key organizer of genome structure and epigenetic regulation in EBV-infected B cells, uncovering a lamin-dependent pathway that connects nuclear architecture, metabolism, and viral disease processes.

ABSTRACT Hutchinson Gilford Progeria Syndrome (HGPS) is an ultra-rare pediatric premature aging disorder. It is caused by a point mutation in the LMNA gene leading to the production of the dominant-negative progerin isoform of the nuclear envelope protein lamin A. Most of the mechanistic insights into the disease have come from studies using cellular or mouse models of HGPS. To probe the clinical relevance of previously implicated cellular pathways and to address the extent of gene expression heterogeneity between patients, we performed transcriptomic analysis of a comprehensive set of HGPS patients. We find misexpression of several cellular pathways, including multiple signaling pathways, the Unfolded Protein Response (UPR) and mesodermal cell fate specification. Variability amongst individual patients was limited, with misregulation of the major pathways observed in most patients. Comparing the transcriptome of patients with an inducible HGPS cell model, we also identified the primary target pathways of the disease-causing progerin protein.

Epithelial-to-mesenchymal transition (EMT) is essential for normal development and cancer progression. However, how nuclear Lamins regulate EMT is unclear. Here, we show that Lamin A/C modulates the epithelial–mesenchymal (E-M) plasticity of cells through its interaction with the chromatin organizer, EZH2. The overexpression of Lamin A reinforces an epithelial identity, while its depletion promotes a mesenchymal phenotype. This positions Lamin A/C as a crucial modulator of Epithelial-Mesenchymal plasticity. Furthermore, CDK1-mediated phosphorylation of Lamin A/C (Ser22) and EZH2 (Thr345) disrupts Lamin A/C–EZH2 interaction, destabilizing EZH2, with a concomitant decrease in the occupancy of the heterochromatin mark (H3K27me3) on the SNAI1, TWIST1, and ZEB1 promoters, thereby facilitating a transition towards mesenchymal transcriptional programs. Conversely, phosphodeficient Lamin A/C (S22A) and EZH2 (T345A) mutants restore epithelial identity, highlighting a regulatory role of the Lamin A/C–EZH2 axis in maintaining epithelial homeostasis. In vivo, xenograft assays in NOD-SCID mice reveal that while phosphorylated Lamin A/C or EZH2 promote tumor growth and metastasis, phospho-deficient mutants markedly suppress it. Lamin A/C–EZH2 interaction regulates the expression of E–M-associated transcription factors, highlighting the role of this interaction in modulating transcriptional plasticity, thereby serving as a potential therapeutic target for regulating metastasis in breast cancers.

Chromatin organization in the mammalian cell nucleus plays a vital role in the regulation of gene expression. The lamina-associated domain at the inner nuclear membrane has been shown to harbor heterochromatin, while the nuclear interior has been shown to contain most of the euchromatin. Here, we show that a sub-set of actively transcribing genes, marked by RNA Pol II pSer2, are associated with Lamin B1 at the inner nuclear envelope in mouse embryonic stem cells (mESCs) and the number of genes proportionally increases upon in vitro differentiation of mESC to olfactory precursor cells. These nuclear periphery-associated actively transcribing genes primarily represent housekeeping genes, and their gene bodies are significantly enriched with guanine and cytosine compared to genes actively transcribed at the nuclear interior. We found the promoters of these gene’s to also be significantly enriched with guanine and to be predominantly regulated by zinc finger protein transcription factors. We provide evidence supporting the emerging notion that the Lamin B1 region is not solely transcriptionally silent.