Tissue repair after spinal cord injury requires the mobilization of immune and glial cells to form a protective barrier that seals the wound and facilitates debris clearing, inflammatory containment ...and matrix compaction. This process involves corralling, wherein phagocytic immune cells become confined to the necrotic core, which is surrounded by an astrocytic border. Here we elucidate a temporally distinct gene signature in injury-activated microglia and macrophages (IAMs) that engages axon guidance pathways. Plexin-B2 is upregulated in IAMs and is required for motor sensory recovery after spinal cord injury. Plexin-B2 deletion in myeloid cells impairs corralling, leading to diffuse tissue damage, inflammatory spillover and hampered axon regeneration. Corralling begins early and requires Plexin-B2 in both microglia and macrophages. Mechanistically, Plexin-B2 promotes microglia motility, steers IAMs away from colliding cells and facilitates matrix compaction. Our data therefore establish Plexin-B2 as an important link that integrates biochemical cues and physical interactions of IAMs with the injury microenvironment during wound healing.
Neural stem cells (NSCs) hold great promise for neural repair in cases of CNS injury and neurodegeneration; however, conventional cell-based transplant methods face the challenges of poor survival ...and inadequate neuronal differentiation. Here, we report an alternative, tissue-based transplantation strategy whereby cerebral organoids derived from human pluripotent stem cells (PSCs) were grafted into lesioned mouse cortex. Cerebral organoid transplants exhibited enhanced survival and robust vascularization from host brain as compared to transplants of dissociated neural progenitor cells (NPCs). Engrafted cerebral organoids harbored a large NSC pool and displayed multilineage neurodifferentiation at two and four weeks after grafting. Cerebral organoids therefore represent a promising alternative source to NSCs or fetal tissues for transplantation, as they contain a large set of neuroprogenitors and differentiated neurons in a structured organization. Engrafted cerebral organoids may also offer a unique experimental paradigm for modeling human neurodevelopment and CNS diseases in the context of vascularized cortical tissue.
The transition from unicellular to multicellular organisms poses the question as to when genes that regulate cell-cell interactions emerged during evolution. The receptor and ligand pairing of ...plexins and semaphorins regulates cellular interactions in a wide range of developmental and physiological contexts. We surveyed here genomes of unicellular eukaryotes and of non-bilaterian and bilaterian Metazoa and performed phylogenetic analyses to gain insight into the evolution of plexin and semaphorin families. Remarkably, we detected plexins and semaphorins in unicellular choanoflagellates, indicating their evolutionary origin in a common ancestor of Choanoflagellida and Metazoa. The plexin domain structure is conserved throughout all clades; in contrast, semaphorins are structurally diverse. Choanoflagellate semaphorins are transmembrane proteins with multiple fibronectin type III domains following the N-terminal Sema domain (termed Sema-FN). Other previously not yet described semaphorin classes include semaphorins of Ctenophora with tandem immunoglobulin domains (Sema-IG) and secreted semaphorins of Echinoderamata (Sema-SP, Sema-SI). Our study also identified Met receptor tyrosine kinases (RTKs), which carry a truncated plexin extracellular domain, in several bilaterian clades, indicating evolutionary origin in a common ancestor of Bilateria. In addition, a novel type of Met-like RTK with a complete plexin extracellular domain was detected in Lophotrochozoa and Echinodermata (termed Met-LP RTK). Our findings are consistent with an ancient function of plexins and semaphorins in regulating cytoskeletal dynamics and cell adhesion that predates their role as axon guidance molecules.
Axon regeneration is hindered by a decline of intrinsic axon growth capability in mature neurons. Reversing this decline is associated with the induction of a large repertoire of ...regeneration-associated genes (RAGs), but the underlying regulatory mechanisms of the transcriptional changes are largely unknown. Here, we establish a correlation between diminished axon growth potential and histone 4 (H4) hypoacetylation. When neurons are triggered into a growth state, as in the conditioning lesion paradigm, H4 acetylation is restored, and RAG transcription is initiated. We have identified a set of target genes of Smad1, a proregenerative transcription factor, in conditioned DRG neurons. We also show that, during the epigenetic reprogramming process, histone-modifying enzymes work together with Smad1 to facilitate transcriptional regulation of RAGs. Importantly, targeted pharmacological modulation of the activity of histone-modifying enzymes, such as histone deacetylases, leads to induction of multiple RAGs and promotion of sensory axon regeneration in a mouse model of spinal cord injury. Our findings suggest epigenetic modulation as a potential therapeutic strategy to enhance axon regeneration.
Mature neurons have diminished intrinsic regenerative capacity. Axotomy of the peripheral branch of adult dorsal root ganglia (a "conditioning" lesion) triggers a transcription-dependent axon growth ...program. Here, we show that this growth program requires the function of the transcription factor Smad1. After peripheral axotomy, neuronal Smad1 is upregulated, and phosphorylated Smad1 accumulates in the nucleus. Both events precede the onset of axonal extension. Reducing Smad1 by RNA interference in vitro impairs axonal growth, and the continued presence of Smad1 is required to maintain the growth program. Furthermore, intraganglionic injection of BMP2 or 4, which activates Smad1, markedly enhances axonal growth capacity, mimicking the effect of a conditioning lesion. Thus, activation of Smad1 by axotomy is a key component of the transcriptional switch that promotes an enhanced growth state of adult sensory neurons.
During morphogenesis, molecular mechanisms that orchestrate biomechanical dynamics across cells remain unclear. Here, we show a role of guidance receptor Plexin-B2 in organizing actomyosin network ...and adhesion complexes during multicellular development of human embryonic stem cells and neuroprogenitor cells. Plexin-B2 manipulations affect actomyosin contractility, leading to changes in cell stiffness and cytoskeletal tension, as well as cell-cell and cell-matrix adhesion. We have delineated the functional domains of Plexin-B2, RAP1/2 effectors, and the signaling association with ERK1/2, calcium activation, and YAP mechanosensor, thus providing a mechanistic link between Plexin-B2-mediated cytoskeletal tension and stem cell physiology. Plexin-B2-deficient stem cells exhibit premature lineage commitment, and a balanced level of Plexin-B2 activity is critical for maintaining cytoarchitectural integrity of the developing neuroepithelium, as modeled in cerebral organoids. Our studies thus establish a significant function of Plexin-B2 in orchestrating cytoskeletal tension and cell-cell/cell-matrix adhesion, therefore solidifying the importance of collective cell mechanics in governing stem cell physiology and tissue morphogenesis.
Effective identification of apple leaf diseases can reduce pesticide spraying and improve apple fruit yield, which is significant to agriculture. However, the existing apple leaf disease detection ...models lack consideration of disease diversity and accuracy, which hinders the application of intelligent agriculture in the apple industry. In this paper, we explore an accurate and robust detection model for apple leaf disease called Apple-Net, improving the conventional YOLOv5 network by adding the Feature Enhancement Module (FEM) and Coordinate Attention (CA) methods. The combination of the feature pyramid and pan in YOLOv5 can obtain richer semantic information and enhance the semantic information of low-level feature maps but lacks the output of multi-scale information. Thus, the FEM was adopted to improve the output of multi-scale information, and the CA was used to improve the detection efficiency. The experimental results show that Apple-Net achieves a higher mAP@0.5 (95.9%) and precision (93.1%) than four classic target detection models, thus proving that Apple-Net achieves more competitive results on apple leaf disease identification.
Background
Cervical cancer seriously threatens both the health and life of women. We aimed to investigate whether RNA interference of long non‐coding RNA (lncRNA) DCST1‐AS1 could promote miR‐874‐3p ...expression to affect the proliferation, migration and invasion of cervical cancer cells.
Methods
DCST1‐AS1 expression levels in cervical cancer cells and transfection effects were detected by quantitative reverse transcriptase‐polymerase chain reaction analysis. Proliferation, invasion and migration of cells were separately shown by cell‐counting kit‐8, wound healing and transwell assays, and relative protein expression was determined by western blot analysis. Dual‐luciferase reporter and RNA immunoprecipitation assays verified the interaction of DCST1‐AS1 and miR‐874‐3p.
Results
DCST1‐AS1 expression was increased in cervical cancer tissues and cells. The DCST1‐AS1 expression in Hela and SiHa cells was the highest, and so the cells were selected for the next experiment. Inhibition of DCST1‐AS1 suppressed the proliferation, invasion and migration of cervical cancer cells and decreased the expression of KI67, proliferating cell nuclear antigen, matrix metalloproteinase (MMP)‐2 and MMP‐9. miR‐874‐3p expression was increased when cells were transfected with miR‐874‐3p mimic or shRNA‐DCST1‐AS1‐1, and DCST1‐AS1 expression was down‐regulated when cells were transfected with miR‐874‐3p mimic. DCST1‐AS1 can directly target miR‐874‐3p. Furthermore, inhibition of miR‐874‐3p could effectively alleviate the effect of inhibition of DCST1‐AS1 with respect to the proliferation, invasion and migration of cervical cancer cells.
Conclusions
Inhibition of DCST1‐AS1 suppressed the proliferation, migration and invasion of cervical cancer cells by increasing miR‐874‐3p expression, which could be alleviated by the inhibition of miR‐874‐3p.
Abstract
Axon regeneration of dorsal root ganglia (DRG) neurons after peripheral axotomy involves reconfiguration of gene regulatory circuits to establish regenerative gene programs. However, the ...underlying mechanisms remain unclear. Here, through an unbiased survey, we show that the binding motif of Bmal1, a central transcription factor of the circadian clock, is enriched in differentially hydroxymethylated regions (DhMRs) of mouse DRG after peripheral lesion. By applying conditional deletion of
Bmal1
in neurons, in vitro and in vivo neurite outgrowth assays, as well as transcriptomic profiling, we demonstrate that Bmal1 inhibits axon regeneration, in part through a functional link with the epigenetic factor Tet3. Mechanistically, we reveal that Bmal1 acts as a gatekeeper of neuroepigenetic responses to axonal injury by limiting Tet3 expression and restricting 5hmC modifications. Bmal1-regulated genes not only concern axon growth, but also stress responses and energy homeostasis. Furthermore, we uncover an epigenetic rhythm of diurnal oscillation of Tet3 and 5hmC levels in DRG neurons, corresponding to time-of-day effect on axon growth potential. Collectively, our studies demonstrate that targeting Bmal1 enhances axon regeneration.
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