A Novel Netrin-1-Derived Peptide Enhances Protection against Neuronal Death and Mitigates of Intracerebral Hemorrhage in Mice

A novel and high-performance tumor inhibitor of La, N co-doped carbon dots for U251 and LN229 cells

To address the medical challenges posed by glioblastoma, a novel and high-performance tumor inhibitor (La@FA-CDs) composed of folic acid and lanthanum nitrate hexahydrate, was successfully synthesized and demonstrated effectiveness in inhibiting the growth of U251 and LN299 cells. The microstructure of La@FA-CDs was extensively analyzed by FTIR, UV-Vis, XPS, TEM, AFM NMR, and nanoparticle size analyzer. The optical and electrical properties of La@FA-CDs were characterized using a fluorescence spectrometer and a zeta potential analyzer. Biological assays, including the CCK8 proliferation assay, scratch assay, flow cytometry, cytoskeleton staining, and live/dead staining were conducted to assess antitumor properties and cytotoxicity. The result revealed that the La50 %@FA-CDs demonstrated significantly enhanced antitumor activity relative to the undoped sample. Furthermore, the La50 %@FA-CDs demonstrated a dose-dependent cytotoxic effect on two glioblastoma cell lines U251 and LN299. The findings of this study suggested that treatment with La50 %@FA-CDs effectively inhibited migration and proliferation while promoting apoptosis in glioblastoma cells. Meanwhile, the La50 %@FA-CDs showed minimal cytotoxic effects on HEK 293 and HUVEC cells under standard conditions, with only slight toxicity observed in HUVEC cells at high (500 µM) concentrations. These results suggest that La50 %@FA-CDs could be a promising therapeutic agent for glioblastoma treatment, demonstrating both effective inhibition and favorable safety profiles.

Five racemic phthalides from the aerial parts of Lycopodiastrum casuarinoides and their neuroprotective activities

Five racemic phthalides (1-5), including four undescribed phthalides monomers [(+)-1, (+)-2, (-)-2 and (-)-3], four undescribed phthalide dimers [(+)-4, (-)-4, (+)-5 and (-)-5], together with two known compounds [(-)-1 and (+)-3], were isolated from the aerial parts of Lycopodistrum casuarinoides. Their chemical structures were delineated by extensive spectroscopic data (UV, 1D/2D NMR, HRESIMS), in combination with the comparison of the experimental and calculated electronic circular dichroism spectra, calculated spin-spin coupling constants, and calculated NMR. All compounds were reported from Lycopodiaceae family for the first time. In addition, all isolates were tested for their neuroprotective effects on HT-22 cell injury induced by glutamate. Interestingly, among the five racemic phthalides, only the homologous dimers [(±)-5] displayed significant differences in neuroprotective effects, and (-)-5 exhibited the best neuroprotective activity against glutamate-induced HT-22 cells damage, with 29.3% increase rate in cell survival at 5 μM concentration. The neuroprotective effect of (-)-5 at different concentrations is equivalent to that of the positive control drug D/L-3-n-butylphthalide (racemic NBP). Furthermore, the biological evaluation revealed that (-)-5 could ameliorate glutamate-induced neuronal cell death via the Bax/Bcl-2 anti-apoptotic pathway.

Netrin-1 Is an Important Mediator in Microglia Migration

Microglia migrate to the cerebral cortex during early embryonic stages. However, the precise mechanisms underlying microglia migration remain incompletely understood. As an extracellular matrix protein, Netrin-1 is involved in modulating the motility of diverse cells. In this paper, we found that Netrin-1 promoted microglial BV2 cell migration in vitro. Mechanism studies indicated that the activation of GSK3β activity contributed to Netrin-1-mediated microglia migration. Furthermore, Integrin α6/β1 might be the relevant receptor. Single-cell data analysis revealed the higher expression of Integrin α6 subunit and β1 subunit in microglia in comparison with classical receptors, including Dcc, Neo1, Unc5a, Unc5b, Unc5c, Unc5d, and Dscam. Microscale thermophoresis (MST) measurement confirmed the high binding affinity between Integrin α6/β1 and Netrin-1. Importantly, activation of Integrin α6/β1 with IKVAV peptides mirrored the microglia migration and GSK3 activation induced by Netrin-1. Finally, conditional knockout (CKO) of Netrin-1 in radial glial cells and their progeny led to a reduction in microglia population in the cerebral cortex at early developmental stages. Together, our findings highlight the role of Netrin-1 in microglia migration and underscore its therapeutic potential in microglia-related brain diseases.

Radioprotective effect of Ginkgolide B on brain: the mediating role of DCC/MST1 signaling

PURPOSE

The risk of brain exposure to ionizing radiation increases gradually due to the extensive application of nuclear technology in medical, industrial, and aerospace fields. Radiation-induced brain injury (RBI) is highly likely to cause a wide range of neurological complications, including schizophrenia, Alzheimer's disease (AD), depression. Ginkgolide B (GB) is one of the effective active components extracted from ginkgo biloba leaves, exerts protective effects on CNS, which is involved in the regulation of the Hippo signaling pathway. MST1, as one of the core kinases of the Hippo pathway, participated in regulating cell proliferation, differentiation, and apoptosis. However, it remains unclear whether GB attenuates radiation brain injury (RBI) and whether the radioprotective effect of GB refers to MST1 signaling. Hence, our study aimed to explore the radiation protection effect and the potential mechanism of GB.

MATERIALS AND METHODS

C57BL/6 mice were stimulated with an X-ray (20 Gy) to establish an RBI model. Then, morris water maze test (MWM) and step-down passive avoidance test (SDPAT) were used to assess the learning and memory function of mice. The open field test (OFT), tail suspension test (TST), and forced swimming test (FST) were used to assess changes in locomotor activity and hopelessness. Besides, X-ray-stimulated SH-SY5Y cells were used to verify the radioprotective effect of GB. Immunofluorescence double staining, Dihydroethidium (DHE), western blot, and flow cytometry were used to explore the role of DCC/MST1 signaling in RBI.

RESULTS

In this study, X-ray-treated mice exhibited cognitive impairment and depression-like behavior, which was ameliorated by GB treatment. GB also reduced the ROS production and the number of TUNEL-positive cells in the hippocampus. Moreover, GB increased the protein levels of p-AKT and Bcl2, while decreased the protein levels of MST1, p-p38, p-JNK, cleaved-caspase-3 and Bax both in vivo and in vitro. Additionally, exogenous Netrin-1 alleviated X-ray-induced ROS production and apoptosis, whereas knockout of Netrin-1 receptor DCC abolished the protective effect of GB.

CONCLUSION

Oxidative stress and MST1-mediated neuronal apoptosis participated in radiation-induced cognitive impairment and depression-like behaviors, and modulation of DCC by GB was an effective intervention against RBI.

DCC/netrin-1 regulates cell death in oligodendrocytes after brain injury

Hallmark pathological features of brain trauma are axonal degeneration and demyelination because myelin-producing oligodendrocytes (OLs) are particularly vulnerable to injury-induced death signals. To reveal mechanisms responsible for this OL loss, we examined a novel class of "death receptors" called dependence receptors (DepRs). DepRs initiate pro-death signals in the absence of their respective ligand(s), yet little is known about their role after injury. Here, we investigated whether the deleted in colorectal cancer (DCC) DepR contributes to OL loss after brain injury. We found that administration of its netrin-1 ligand is sufficient to block OL cell death. We also show that upon acute injury, DCC is upregulated while netrin-1 is downregulated in perilesional tissues. Moreover, after genetically silencing pro-death activity using DCCD1290N mutant mice, we observed greater OL survival, greater myelin integrity, and improved motor function. Our findings uncover a novel role for the netrin-1/DCC pathway in regulating OL loss in the traumatically injured brain.

Abietane diterpenoids from Phlegmariurus carinatus and their biological activities

Five undescribed abietane diterpenoids, along with eight known analogs, were isolated from Phlegmariurus carinatus. Their structures were unambiguously elucidated by extensive analysis of spectroscopic data and comparison between the literature. The absolute configuration of phlecarinatone C was determined by evaluating ECD spectra. Four undescribed abietane diterpenoids and eight known analogs were tested for their neuroprotective and cytotoxic activities, separately. Teuvincenone C showed potential neuroprotective effect against Hemin-induced HT22 cell damage. Importantly, phlecarinatone C showed pronounced cytotoxic effect against U251 cells in vitro assays. The biological evaluation revealed that phlecarinatone C could inhibit proliferation, migration, and invasion in a concentration-dependent manner of U251 cells. Meanwhile, phlecarinatone C effectively reversed epithelial-to-mesenchymal transition (EMT) and promoted U251 cells apoptosis via a mitochondrial apoptotic pathway. Taken together, phlecarinatone C might be a valuable candidate for anti-metastatic agents against glioblastoma treatment.

Bone Marrow Mesenchymal Stem Cells (BMSCs) Expressing Netrin-1 Alleviates Spinal Cord Injury (SCI)-Induced Inflammation

Spinal cord injury (SCI) is a common central nervous system (CNS) injury. Bone marrow mesenchymal stem cells (BMSCs) transplantation is a potential treatment for traumatic SCI. However, the role and mechanism of BMSCs with high expression of Netrin-1 on the repair and inflammation of spinal cord injury cells remains unclear. Our study intends to assess the effect of BMSCs with high Netrin-1 level on the repair of SCI cells. BMSCs or Netrin-1 transfected BMSCs were co-cultured with mechanically injured nerve cells followed by analysis of the differentiation of BMSCs by light microscope, apoptosis activity, expression of TLR-4 and NF-κB, and the TNF-α and IL-1β content in cell supernatant by ELISA. BMSCs with high Netrin-1 expression promoted the proliferation of BMSCs, inhibited apoptosis, and promoted the differentiation of nerve cells along with increased ALK activity, and the expression of GFAP and BDNF. Co-culture with BMSCs or BMSCs with high Netrin-1 expression increased mechanically damaged nerve cell proliferation, decreased apoptosis, downregulated TLR-4 and NF-κB (P < 0.05) with more significant changes after co-culture with BMSCs with high Netrin-1 expression. In conclusion, Netrin-1 can promote BMSCs proliferation and differentiation, and inhibit apoptosis. By inhibiting inflammation, it can promote damaged nerve cell proliferation and repair.