Role of nuclear ATPases in nuclear mechanics and cell migration through confined spaces: Opposite effects of BRG1 and cohesin.

Conidiation is the primary mode of reproduction in filamentous fungi and is essential for the dispersal of pathogenic species. However, the fundamental cellular mechanisms regulating conidiation in plant pathogenic fungi remain largely unexplored. Here, using Verticillium dahliae as a model, we investigated the dynamic assembly and function of the contractile actomyosin ring (CAR) and septins during conidiation through live-cell imaging. We show that septins, visualized via VdCdc11-GFP, first accumulate at the tip of budding hyphae during the transition from hyphal elongation to apical budding, and undergo an hourglass-to-double-ring transition at the bud neck. Following mitosis, myosin II and actin assemble simultaneously into a contractile ring to drive cytokinesis. Disruption of core septin function results in defective nuclear segregation and aberrant nuclear migration during mitosis, as well as delayed recruitment of myosin II to the bud neck, indicating that septins scaffold cytokinetic machinery and coordinate nuclear division during conidiation. In contrast, during hyphal septation, myosin II, actin, and septins appear simultaneouslyas a diffuse cortical band, with septin organization dependent on actin. Collectively, these findings reveal distinct spatial and temporal coordination between actomyosin and septins in two cytokinetic contexts-conidiation and hyphal septation-and define apical budding as a specialized cytokinesis mode in V. dahliae. Our study broadens the understanding of fungal cytokinesis beyond yeast models to multicellular filamentous fungi.

GmSRC7 is a broad-spectrum antiviral R gene from soybean, but its downstream and functionally related genes remain unclear. Virus-induced gene silencing (VIGS) assays in Nicotiana benthamiana (Nb) showed that suppression of several gene families—WRKY transcription factors, chaperones, ethylene pathway components, MAPK cascade elements, salicylic acid (SA) signaling genes, calcium-dependent protein kinases, nuclear migration proteins, RNA replication-related genes, and immune regulators—consistently weakened GmSRC7-mediated resistance to Soybean Mosaic Virus (SMV) and Tobacco Mosaic Virus (TMV). Targeted silencing of four regulatory genes—NbEDS1, NbARF1, NbSGT1, and NbCOI1—markedly enhanced GmSRC7-mediated resistance to SMV and TMV in our experiments. Silencing the serine/threonine kinase gene NbPBS1 increased GmSRC7-conferred resistance to SMV but did not significantly alter its resistance to TMV. Transient expression assays showed that NbARF1, NbSGT1, and NbCOI1 antagonize GmSRC7-mediated defense against SMV and TMV, whereas NbPBS1 specifically suppresses anti-SMV activity without affecting TMV resistance. Transient overexpression of SA-degrading enzymes (AtS3H, AtS5H, and NahG) significantly reduced GmSRC7-conferred resistance to SMV, indicating that SA is essential for this R protein-mediated defense. Genes were also grouped by immune pathways and function: co-expression of chaperone family genes inhibited GmSRC7 activity against SMV and TMV, while co-expression of WRKY family genes enhanced anti-SMV activity of GmSRC7. Finally, transient silencing of soybean genes GmEDS1, GmSGT1-1, GmSGT1-2, GmJAR1, and GmSGS3 compromised GmSRC7-mediated resistance to SMV.

Proliferative vitreoretinopathy (PVR) is a vision-threatening fibrotic retinal disorder characterized by the epithelial-mesenchymal transition (EMT) of retinal pigment epithelial (RPE) cells. In this study, we established a pathophysiologically relevant in vitro model by co-stimulating ARPE-19 cells with transforming growth factor beta 2 (TGFB2) and tumor necrosis factor-alpha (TNF), referred to as ‘TNT’, and evaluated the anti-fibrotic and anti-angiogenic effects of Nicotinamide (NAM), a vitamin B3 derivative previously reported to counteract fibrosis in various disease models. Confluent ARPE-19 cells were treated with TGFB2, TNF, or TNT for up to six days. EMT progression was assessed via immunocytochemistry, Western blotting, and collagen gel contraction assays. Live-cell imaging (LCI) combined with Hoechst 33342 nuclear staining and automated tracking using Fiji/TrackMate enabled real-time analysis of cell migration and multicellular aggregation. VEGFA secretion was quantified by ELISA. TNT stimulation induced synergistic EMT-like features, including cell elongation, directional migration, extracellular matrix (ECM) remodeling, gel contraction, and formation of multicellular aggregates. TrackMate-based analysis revealed coordinated nuclear migration under TNT conditions. VEGFA secretion was significantly elevated at early time points. NAM co-treatment reduced ECM protein expression (FN1, COL1A1), attenuated migration and contraction, and significantly lowered VEGFA release. This TNT-based ARPE-19 model represents a robust, live-cell-compatible in vitro system that mimics both fibrotic and pro-angiogenic aspects of PVR. It allows real-time assessment of EMT progression and is suitable for screening anti-fibrotic compounds. Our findings suggest that Nicotinamide mitigates both fibrotic and angiogenic responses in this model and may hold therapeutic potential for fibrotic retinal diseases.

Proliferative vitreoretinopathy (PVR) is a vision-threatening fibrotic retinal disorder characterized by the epithelial-mesenchymal transition (EMT) of retinal pigment epithelial (RPE) cells. In this study, we established a pathophysiologically relevant in vitro model by co-stimulating ARPE-19 cells with transforming growth factor beta 2 (TGFB2) and tumor necrosis factor-alpha (TNF), referred to as 'TNT', and evaluated the anti-fibrotic and anti-angiogenic effects of Nicotinamide (NAM), a vitamin B3 derivative previously reported to counteract fibrosis in various disease models. Confluent ARPE-19 cells were treated with TGFB2, TNF, or TNT for up to six days. EMT progression was assessed via immunocytochemistry, Western blotting, and collagen gel contraction assays. Live-cell imaging (LCI) combined with Hoechst 33342 nuclear staining and automated tracking using Fiji/TrackMate enabled real-time analysis of cell migration and multicellular aggregation. VEGFA secretion was quantified by ELISA. TNT stimulation induced synergistic EMT-like features, including cell elongation, directional migration, extracellular matrix (ECM) remodeling, gel contraction, and formation of multicellular aggregates. TrackMate-based analysis revealed coordinated nuclear migration under TNT conditions. VEGFA secretion was significantly elevated at early time points. NAM co-treatment reduced ECM protein expression (FN1, COL1A1), attenuated migration and contraction, and significantly lowered VEGFA release. This TNT-based ARPE-19 model represents a robust, live-cell-compatible in vitro system that mimics both fibrotic and pro-angiogenic aspects of PVR. It allows real-time assessment of EMT progression and is suitable for screening anti-fibrotic compounds. Our findings suggest that Nicotinamide mitigates both fibrotic and angiogenic responses in this model and may hold therapeutic potential for fibrotic retinal diseases.

During the development of the rice female gametophyte (FG, embryo sac), there exists a free-nuclear stage wherein eight nuclei, originating from the same mother cell nucleus, respectively migrate to specific positions to acquire distinct cell identities after cellularization and develop into the egg cell, central cell, or accessory cells. Therefore, this nuclear migration stage is essential for fertilization and rice fertility. How these nuclei can find their own way to exactly move to different predetermined positions and how the two polar nuclei are selected have been intriguing questions for decades. Here, we show that a mitogen-activated protein kinase cascade, composed of OsMEKK2/OsMEKK21, OsMKK6, and OsMPK4, precisely regulates free-nuclear migration and determines the number and identities of polar nuclei. Specifically, OsMKK6 phosphorylates OsMPK4 to restrict nuclear migration at the chalazal pole, ensuring the accurate number and positioning of antipodal cells and polar nuclei. Loss-of-function mutations in OsMKK6 and OsMPK4 result in an excess of polar nuclei at the expense of antipodal cells. Additionally, OsMEKK2 and OsMEKK21 function as upstream regulators, phosphorylating and modulating downstream substrates to control nuclear migration at both poles. This regulation is essential for FG fertility and seed production. Our findings reveal a hierarchical model for the regulation of nuclear migration during embryo sac development and provide valuable insights into how an embryo sac orchestrates the migration of eight nuclei in response to different positional cues, thereby establishing female fertility in rice.

SUMMARYLive imaging data analysis often requires an objective, local, and accurate way of quantification of cell dynamics. In the research field of polarized tip‐growth, the cell fluctuations and/or fluctuations in tip position and growth direction hamper automated analyses of huge amounts of imaging sequences. The fluctuated nature in data makes it unclear how cell shape and growth are linked to intracellular events that could be the actual driving force of cell growth. To overcome these difficulties, we developed a powerful and user‐friendly tool called KymoTip with an available format. In this software, novel functions such as coordinate normalization, tip‐bottom detection, and signal kymograph were implemented. We confirmed that not only plasma membrane‐labeled fluorescent images, but also images such as bright‐field and cortical microtubule markers—so long as the cell contours can be identified—are amenable to KymoTip. Furthermore, by combining markers for cell contours with those that visualize intracellular structures, it becomes possible to quantitatively analyze various intracellular events, such as nuclear migration and calcium wave, in conjunction with cellular growth dynamics. Since KymoTip can be handled by non‐specialists, it is expected to promote understanding of what happens at the sub‐ and cellular level with high‐throughput outcomes.

The aim of this study was to evaluate the induced reproduction and embryonic development of the four-banded prochilod (Schizodon fasciatus) in the Peruvian Amazon. Five females with oocytes showing nuclear migration and five males that released seminal fluid under slight pressure were selected. Buserelin acetate (Conceptase) in injectable solution was used as a hormonal inducer, with doses of 1.3 ml/kg for females and 0.5 ml/kg for males. Spawning and wet fertilization were carried out in circular tanks where the fertilized and hydrated eggs were collected. Incubation was performed in 40 L Woynarovich-type incubators, where embryonic development was characterized. The females spawned 42.2 L of fertilized and hydrated eggs with a diameter of 3.33 ± 0.29 mm. During incubation (13 to 15 hours), the organogenesis to hatching phase was described, resulting in a total of 626 781 larvae with a total length of 3.00 ± 0.09 mm and a hatching rate of 84.80 ± 2.71%. This study successfully achieved induced reproduction and described the embryonic development of Schizodon fasciatus, an economically important species with the potential to diversify aquaculture and contribute to food security.

Meiosis is a conserved yet evolutionarily varied process underpinning sexual reproduction in eukaryotes. In the malaria parasite Plasmodium, meiosis is unconventional: it occurs immediately after fertilisation (post-zygotic) and must be coordinated with the transformation of the zygote into a motile ookinete. The mechanisms synchronising these meiotic and morphogenetic programmes remain unknow. Here, we identify the Plasmodium berghei NIMA-related kinase, NEK4 as a key regulator that couples meiotic initiation with zygote morphogenesis. Using ultrastructure expansion microscopy, we show that NEK4 accumulates at the microtubule-organising centre (MTOC) and the apical polar complex (APC) shortly after fertilisation, preceding the assembly of perinuclear and cortical microtubules. We reveal that Plasmodium zygotes undergo a nuclear migration driven by the MTOC, analogous to the meiotic nuclear movement in fission yeast. Deletion of nek4 results in complete developmental arrest: MTOC duplication and microtubule formation are blocked, chromatin remains uncondensed, and nuclear migration and cell polarity fail to establish. Transcriptomic and phosphoproteomic analyses reveal that NEK4 absence causes a collapse in transcriptional and phosphoregulatory networks governing meiosis and cytoskeletal organisation, leading to reduced expression and phosphorylation of important players, including HOP1, REC8, and AP2-O. These findings establish NEK4 as a key regulator driving meiotic entry and zygote maturation.

Cell proliferation is a key driver of morphogenesis and body plan transformation in multicellular animals, yet its spatial organization remains poorly understood in many non-segmented spiralians. In this study, we examine the dynamics of cell division during larval growth and metamorphosis in the larvae and early juveniles of the phoronid Phoronopsis harmeri, using EdU incorporation, anti-phospho-histone H3 immunostaining, confocal laser scanning microscopy, and electron microscopy. Early larval proliferation is partly regionalized from the outset and becomes progressively more localized toward metamorphosis. We identify a tripartite organization of proliferative activity: (1) posterior ring-shaped domains in the telotroch that persist through metamorphosis and support elongation and anal chamber formation; (2) regional proliferative zones at tentacle bases, preoral and postoral regions; and (3) scattered proliferation driving the expansion of the trunk epidermis. This coexistence of posterior, regional, and scattered patterns underscores the developmental plasticity of phoronids and the diversity of growth strategies within Spiralia. Posterior proliferative domains in phoronids contribute important context to homology-convergence debates on posterior growth across spiralians, but are not decisive by themselves; viewed with the distributed epithelial proliferation, they underscore the coexistence of multiple proliferative programs within a single life cycle. In addition, we identify atypical mitotic characteristics in this species, including unconventional metaphase organization and signs of interkinetic nuclear migration in larval epithelia. Our results suggest that phoronids provide a valuable model for exploring how diverse architectures of cell proliferation contribute to larval growth, body elongation, and morphogenetic compartmentalization in Lophotrochozoa.

Human cytomegalovirus (HCMV) disrupts the inner nuclear Lamin A/C meshwork to facilitate virion egress. Here, we show that targeting Lamin A/C also plays a previously unrecognized role in HCMV-induced rewiring of cytoskeletal connections that control nuclear movement and cell migration at later stages of infection. Specifically, HCMV was found to employ distinct strategies to downregulate Lamin A/C and SUN2, which together regulate linker of nucleoskeleton and cytoskeleton (LINC) complexes that most often connect the nuclear membrane with cytoplasmic actin filaments. Unexpectedly, inhibition of the viral kinase, pUL97, or expression of nonphosphorylatable mutants of Lamin A/C failed to restore SUN2 expression or significant actin filament assembly. Moreover, exogenous reexpression of SUN2 also failed to restore actin filaments. Instead, restoration of SUN2 or Lamin A/C expression impaired the formation of acetylated microtubules in infected cells. Furthermore, inhibition of pUL97, expression of Lamin A/C mutants or depletion of the tubulin acetyl transferase, ATAT1, all impaired HCMV-induced nuclear movement and cell migration. Our findings reveal that HCMV uses multiple strategies to selectively downregulate Lamin A/C and SUN2 in order to prevent these proteins from interfering with the formation of acetylated microtubules that mediate nuclear movement and cell migration, revealing additional roles for Lamin A/C remodeling during infection and insights into how cells control cytoskeletal interactions with the nucleus.

Meiosis is a conserved yet evolutionarily varied process underpinning sexual reproduction in eukaryotes. In the malaria parasite Plasmodium , meiosis is unconventional: it occurs immediately after fertilisation (post-zygotic) and must be coordinated with the transformation of the zygote into a motile ookinete. The mechanisms synchronising these meiotic and morphogenetic programmes remain unknow. Here, we identify the Plasmodium berghei NIMA-related kinase, NEK4 as a key regulator that couples meiotic initiation with zygote morphogenesis. Using ultrastructure expansion microscopy, we show that NEK4 accumulates at the microtubule-organising centre (MTOC) and the apical polar complex (APC) shortly after fertilisation, preceding the assembly of perinuclear and cortical microtubules. We reveal that Plasmodium zygotes undergo a nuclear migration driven by the MTOC, analogous to the horsetail nuclear movement of fission yeast. Deletion of nek4 results in complete developmental arrest: MTOC duplication and microtubule formation are blocked, chromatin remains uncondensed, and nuclear migration and cell polarity fail to establish. Transcriptomic and phosphoproteomic analyses reveal that NEK4 absence causes a collapse in transcriptional and phosphoregulatory networks governing meiosis and cytoskeletal organisation, leading to reduced expression and phosphorylation of important players, including HOP1, REC8, and AP2-O. These findings establish NEK4 as a key regulator driving meiotic entry and zygote maturation.

Epithelial cell division maintains tissue architecture through coordinated nuclear migration, cell shape changes, and spindle orientation. In columnar epithelia, interkinetic nuclear migration (INM) involves apical nuclear translocation in G2 and basal return post-mitosis, yet its regulation and physiological significance remain understudied due to limited live imaging in vivo models. We adapted the zebrafish embryonic otic vesicle as an in vivo model to study epithelial division dynamics using high-resolution live imaging and genetic tools. We find that apical INM initiates in mid-to-late G2 and is driven by dynein, not myosin II. Mitotic rounding is achieved via actomyosin-mediated basolateral constriction while maintaining basal attachment. Inhibiting myosin II impairs rounding and planar division, causing apical retention of daughter cells, suggesting planar division ensures proper integration. We extend our analysis to the mouse epididymis epithelium, comparing nuclear migration, cell shape, and spindle orientation across species. Our work introduces optimized in vivo models and reveals conserved and tissue-specific mechanisms maintaining structure and function of columnar epithelia.

Polystyrene microplastic (PS-MP), known as a white pollutant, exhibited adverse effects on aquatic and terrestrial animals. The present study aims to evaluate the dose-dependent effect of polystyrene microplastics on skeletal muscle energy metabolism in Wistar rats. PS-MP was administered orally in Wistar rats at doses of 0.5mg/L, 5mg/L, and 50mg/L in drinking water for 28 days daily. After the treatment, metabolic profile and tissue histological analyses were performed. Average food consumption by the treated rats was decreased by PS-MPs. Glycogen and pyruvate contents were depleted in a dose-responsive fashion. Lactate dehydrogenase and transaminase activities were decreased by PS-MP exposure. Free amino nitrogen was mobilized from blood to skeletal muscle in response to stress. Protein content depleted in the muscular tissue whereas enhanced carbonylated protein formation. Pronase and cathepsin activities were increased by PS-MP. Inhibited TCA cycle enzyme activities were observed in the target tissue. Moreover, muscle hypertrophy, nuclear migration, and fibrillation were seen in histological sections. Decreased food consumption by PS-MP exposure could promote glucose scarcity in blood. Depletion of muscular glycogen may result from increased glycogenolysis to replenish loss of blood glucose. Reduction in pyruvate content may result from decreased glycolysis which could perturb the lactate dehydrogenase function. Lack of transaminase in the target tissue was indicative of tissue damage. Muscular protein breakdown might be due to oxidative denaturation of native proteins as well as increased proteolysis. Due to less pyruvate production, the TCA cycle enzyme functions were suppressed. Histopathological studies established significant degenerative changes in muscular morphology following PS-MP exposure. The present study suggests that PS-MP perturbed skeleto-muscular energy metabolism and promoted muscle fiber degeneration following sub-acute exposure.

BackgroundFamily migration is a trend of domestic population migration in China. However, few studies have investigated the impact of family migration on the health-related quality of life (HRQoL) of migrants.ObjectiveTo understand the health-related quality of life (HRQoL) of migrants during urban development in China, and to analyze its influencing factors from the perspective of integrating family migration patterns with individual health behaviors.MethodWilcoxon rank sum test and Kruskal-Wallis H test were used to analyze the differences in health-related quality of life among the migrants. Multiple linear regression method was used to analyze the relationship between family migration, health behavior and quality of life.ResultsA total of 935 valid questionnaires were collected. The utility index of the migrants was 1.00 (0.80,1.00), and the EQ-VAS score was 83 (73,90). The results of univariate analysis showed that migrants living with spouse and children, near migration, high self-rated family economic status, adherence to reasonable diet, moderate exercise and adequate sleep had higher health-related quality of life (P < 0.05). Multivariate analysis showed that family and migration factors such as nuclear family migration degree, migration distance, and self-rated family economic status (P < 0.05), personal health and health behavior factors such as dietary habits, weekly exercise time, sleep time, and the number of chronic diseases (P < 0.05) were associated with the health-related quality of life of migrants. Migrants had more difficulties in “pain/discomfort” and “anxiety/depression”, accounting for 25.2% and 31.3%, respectively.ConclusionFamily-related factors such as nuclear family members not migrating together, long distance migration, poor family economic status, and personal factors such as not adhering to health behaviors and the coexistence of multiple chronic diseases could weaken the health-related quality of life of migrants. Pain/discomfort and anxiety/depression were the main health problems affecting migrants. For this reason, attention should be paid to migrants such as those living alone or with low incomes. In addition, improving the health literacy and health behavior of migrants by promoting healthy lifestyle, carrying out mental health activities, and strengthening health management services can help promote the social integration of migrants and promote the development of cities.

The KASH protein UNC-83 differentially regulates kinesin-1 activity to control developmental stage-specific nuclear migration.

Glycolysis provides the main energy source for the rapid proliferation and migration of colorectal cancer (CRC) cells. In our previous studies, we reported that SUN5, a nuclear membrane protein, promotes proliferation and migration. However, whether SUN5 is involved in the process of glycolysis is unclear. Here, we demonstrate that overexpression of SUN5 enhances glucose uptake and lactate production in CRC cells, whereas the opposite results are observed in SUN5-knockdown cells. Mechanistically, SUN5 activates the NF-κB signaling pathway, which can be inhibited by the IKK inhibitor BAY11-7082. Further studies reveal that SUN5 interacts with TRIM28 to increase IκB α ubiquitination, leading to the nuclear translocation of phosphorylated P65 (phos-P65) and subsequent increases in the transcription of GLUT1 and LDHA, accelerating glycolysis. Moreover, xenograft transplantation experiments reveal that the knockdown of SUN5 inhibits glycolysis and tumorigenesis in vivo. Taken together, these findings indicate that SUN5 enhances the glycolysis and tumorigenesis of CRC cells via interaction with TRIM28, which provides a potential target for the diagnosis and treatment of CRC.

Deformation of the nucleus often presents a barrier to cell migration through tight spaces, such as those encountered as cells move through tissues or across extracellular matrix barriers. Reorganization of the nucleus to allow its passage through spaces much smaller than its resting diameter requires forces generated by the cytoskeleton, as well as active reorganization within the nucleus driven by ATPases that crosslink or move chromatin. Here, we show that two different nuclear ATPases, the BRG1/SMARCA4 motor of the BAF or SWI/SNF complex and the bifunctional crosslinking and loop extruding complex, cohesin, have opposite effects on the stiffness of isolated nuclei. Inhibition of BRG1 stiffens the nucleus, and cohesin softens it in karyoplasts derived from multiple cell types, including four different cancer cells, fibroblasts, and mesenchymal stem cells. The effects on isolated nuclear stiffness coincide with the effects of these ATPases on the ability of cells to migrate through tight spaces. Stiffening the nucleus inhibits single cell migration through micron-sized pores and the outward migration of tumor cell spheroids into a surrounding collagen matrix. Softening the nucleus by inhibiting cohesin has the opposite effect: it enhances single-cell migration through pores, at least for some cell types, and facilitates the outgrowth of cells from a tumor cell spheroid into the surrounding matrix. These results emphasize the importance of active motions generated within the nucleus for the global mechanics of the nucleus and the way that it deforms in response to externally generated stresses.

Endoplasmic reticulum (ER) stress triggers activation of the ER surveillance (ERSU) pathway- a critical protective mechanism that transiently halts cortical ER inheritance to daughter cells and arrests cytokinesis by septin ring subunit Shs1 re-localization to the bud scar in response to ER stress. Once ER functional homeostasis is re-established, cells resume normal cell cycle progression; however, the molecular circuitry linking ER integrity to cell cycle regulation has remained largely unresolved. Here, we show that ER stress selectively disperse Bud2, a GAP for Bud1/Rsr1, severing its canonical role in cell polarity while integrating it into ER homeostasis signaling. Bud2 dispersion results in accelerated spindle pole body (SPB) duplication, spindle misorientation, defects in nuclear migration, and genome segregation errors under ER stress. Strikingly, a C-terminal truncation of Shs1 ( shs1-ΔCTD ) recapitulated the ER stress-induced dispersion of Bud2 phenotype even in the absence of ER stress, and delayed cell-cycle re-entry after ER homeostasis was regained-despite normal occurrence of typical ERSU hallmark events. Notably, Bud2 overexpression rescued the growth defects of shs1-ΔCTD mutants after ER homeostasis was re-established. Collectively, our findings reveal a new mechanistic axis whereby ER integrity coordinates organelle inheritance, cytoskeletal organization, and nuclear division via selective control of Bud2 and Shs1, establishing a direct regulatory bridge between ER status and mitotic fidelity.

Gastrodin promotes osteogenic differentiation by stimulating the Wnt/β-catenin signaling pathway.