PRMT5-mediated homologous recombination repair is essential to maintain genomic integrity of neural progenitor cells.

Maintaining genomic stability is a prerequisite for proliferating NPCs to ensure genetic fidelity. Though histone arginine methylation has been shown to play important roles in safeguarding genomic stability, the underlying mechanism during brain development is not fully understood. Protein arginine N-methyltransferase 5 (PRMT5) is a type II protein arginine methyltransferase that plays a role in transcriptional regulation. Here, we identify PRMT5 as a key regulator of DNA repair in response to double-strand breaks (DSBs) during NPC proliferation. Prmt5F/F; Emx1-Cre (cKO-Emx1) mice show a distinctive microcephaly phenotype, with partial loss of the dorsal medial cerebral cortex and complete loss of the corpus callosum and hippocampus. This phenotype is resulted from DSBs accumulation in the medial dorsal cortex followed by cell apoptosis. Both RNA sequencing and in vitro DNA repair analyses reveal that PRMT5 is required for DNA homologous recombination (HR) repair. PRMT5 specifically catalyzes H3R2me2s in proliferating NPCs in the developing mouse brain to enhance HR-related gene expression during DNA repair. Finally, overexpression of BRCA1 significantly rescues DSBs accumulation and cell apoptosis in PRMT5-deficient NSCs. Taken together, our results show that PRMT5 maintains genomic stability by regulating histone arginine methylation in proliferating NPCs.

Mast cell degranulation-triggered by SARS-CoV-2 induces tracheal-bronchial epithelial inflammation and injury.

SARS-CoV-2 infection-induced hyper-inflammation is a key pathogenic factor of COVID-19. Our research, along with others', has demonstrated that mast cells (MCs) play a vital role in the initiation of hyper-inflammation caused by SARS-CoV-2. In previous study, we observed that SARS-CoV-2 infection induced the accumulation of MCs in the peri-bronchus and bronchioalveolar-duct junction in humanized mice. Additionally, we found that MC degranulation triggered by the spike protein resulted in inflammation in alveolar epithelial cells and capillary endothelial cells, leading to subsequent lung injury. The trachea and bronchus are the routes for SARS-CoV-2 transmission after virus inhalation, and inflammation in these regions could promote viral spread. MCs are widely distributed throughout the respiratory tract. Thus, in this study, we investigated the role of MCs and their degranulation in the development of inflammation in tracheal-bronchial epithelium. Histological analyses showed the accumulation and degranulation of MCs in the peri-trachea of humanized mice infected with SARS-CoV-2. MC degranulation caused lesions in trachea, and the formation of papillary hyperplasia was observed. Through transcriptome analysis in bronchial epithelial cells, we found that MC degranulation significantly altered multiple cellular signaling, particularly, leading to upregulated immune responses and inflammation. The administration of ebastine or loratadine effectively suppressed the induction of inflammatory factors in bronchial epithelial cells and alleviated tracheal injury in mice. Taken together, our findings confirm the essential role of MC degranulation in SARS-CoV-2-induced hyper-inflammation and the subsequent tissue lesions. Furthermore, our results support the use of ebastine or loratadine to inhibit SARS-CoV-2-triggered degranulation, thereby preventing tissue damage caused by hyper-inflammation.

Effect of berbamine on invasion and metastasis of human liver cancer SMMC-7721 cells and its possible mechanism.

Berbamine is a bisbenzylisoquinoline alkaloid extracted from Berberis poiretii of Berberis of Berberidaceae. It has been reported that it can significantly inhibit the proliferation of a variety of malignant tumor cells, including liver cancer. However, the effect of berbamine on the invasion and metastasis of liver cancer has not been reported. The present study demonstrated that berbamine inhibited the migration and invasion of SMMC-7721 cells in a concentration-dependent manner and obviously increased the gap junction function and the expression of Cx32 in SMMC-7721 cells compared with control group. However, after silencing Cx32, berbamine had no significant effect on cell invasion and metastasis. Before silencing Cx32, the expression of PI3K and P-AKT were decreased after berbamine treated on SMMC-7721 cells for 24 h. After silencing Cx32, the expression of PI3K and P-AKT were increased in SMMC-7721 cells. The expression of PI3K and P-AKT had no significant effect after berbamine treated on SMMC-7721 cells for 24 h with silencing Cx32. In conclusion, the results of the present study suggest that berbamine could inhibit the SMMC-7721 cell migration and invasion, and its mechanism may be related to the regulation of PI3K/AKT signaling pathway by enhancing the expression of Cx32.

The ctDNA-based postoperative molecular residual disease status in different subtypes of early-stage breast cancer.

Background: Breast cancer is a highly heterogeneous disease. Early-stage, non-metastatic breast cancer is considered curable after definitive treatment. Early detection of tumor recurrence and metastasis through sensitive biomarkers is helpful for guiding clinical decision-making and early intervention in second-line treatment, which could improve patient prognosis and survival. Methods: In this real-world study, we retrospectively analyzed 82 patients with stages I to III breast cancer who had been analyzed by molecular residual disease (MRD) assay. A total of 82 tumor tissues and 224 peripheral blood samples were collected and detected by next-generation sequencing (NGS) based on a 1,021-gene panel in this study. Results: MRD positivity was detected in 18 of 82 patients (22.0%). The hormone receptor-/human epidermal growth factor receptor 2+ (HR-/HER2+) subgroup had the highest postoperative MRD detection rate at 30.8% (4/13). The BRCA2 and SLX4 genes were significantly enriched in all patients in the MRD positive group and FGFR1 amplification was significantly enriched in the MRD negative group with HR+/HER2-. The number of single nucleotide variants (SNVs) in tissue samples of MRD-positive patients was higher than that of MRD-negative patients (11.94 vs. 8.50 SNVs/sample). Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis showed that there was a similar biological function of the tumor-mutated genes in the 2 MRD status groups. Conclusions: This real-world study confirmed that patient samples of primary tumor tissue with different MRD status and molecular subtypes had differential genetic features, which may be used to predict patients at high risk for recurrence.

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

It has been reported that Netrin-1 is involved in neuroprotection following injury to the central nervous system. However, the minimal functional domain of Netrin-1 which can preserve the neuroprotection but avoid the major side effects of Netrin remains elusive. Here, we investigated the neuroprotective effect of a peptide E1 derived from Netrin-1's EGF3 domain (residues 407-422). We found that it interacts with deleted colorectal carcinoma (DCC) to activate focal adhesion kinase phosphorylation exhibiting neuroprotection. The administration of the peptide E1 was able to improve functional recovery through reduced apoptosis in an experimental murine model of intracerebral hemorrhage (ICH). In summary, we reveal a functional sequence of Netrin-1 that is involved in the recovery process after ICH and identify a candidate peptide for the treatment of ICH.

Nucleus Accumbens Tac1-Expressing Neurons Mediate Stress-Induced Anhedonia-like Behavior in Mice.

Major depressive disorder (MDD) presents with two primary symptoms: depressed mood and anhedonia, which suggests that distinct neuronal circuits may regulate MDD. However, the underlying circuits of these individual symptoms linked to depression remain elusive. Herein, we identify a discrete circuit of tachykinin precursor 1 (Tac1)-expressing neurons in the nucleus accumbens (NAc) lateral shell, which project to ventral pallidum and contribute to stress-induced anhedonia-like behavior. Selective inhibition and activation of Tac1NAc neurons bidirectionally modulate stress susceptibility, revealing that Tac1 neurons in the NAc are critical for regulating anhedonia-like behaviors. We find that a subpopulation of VP neurons receives inhibitory inputs from Tac1NAc neurons and exhibits decreased excitability in susceptible mice. Furthermore, the inhibition of the neurokinin 1 receptor promotes susceptibility to social stress. Overall, our study reveals a discrete circuit regulating anhedonia-like behavior in mice.

Multifunctional Fe3O4@polydopamine core-shell nanocomposites for intracellular mRNA detection and imaging-guided photothermal therapy.

Multifunctional nanocomposites have the potential to integrate sensing, diagnostic, and therapeutic functions into a single nanostructure. Herein, we synthesize Fe3O4@polydopamine core-shell nanocomposites (Fe3O4@PDA NCs) through an in situ self-polymerization method. Dopamine, a melanin-like mimic of mussel adhesive proteins, can self-polymerize to form surface-adherent polydopamine (PDA) films onto a wide range of materials including Fe3O4 nanoparticles used here. In such nanocomposites, PDA provides a number of advantages, such as near-infrared absorption, high fluorescence quenching efficiency, and a surface for further functionalization with biomolecules. We demonstrate the ability of the Fe3O4@PDA NCs to act as theranostic agents for intracellular mRNA detection and multimodal imaging-guided photothermal therapy. This work would stimulate interest in the use of PDA as a useful material to construct multifunctional nanocomposites for biomedical applications.

[Study on EEG changes after occlusal trauma during sleep in rats].

PURPOSE: To explore the electroencephalogram (EEG) changes after occlusal trauma in rats. METHODS: Health Wistar rats were divided into 2 groups: traumatic occlusion group (1-day, 3-day, 7-day, 14-day, 28-day group) and control group. The electrodes were inserted in the hippocampus of anesthetized rats guided by stereotaxic apparatus of brain and then the hippocampal EEG were recorded during sleep. Data were analysed by SPSS 17.0 software package for ANOVA. RERULTS: The δ waves were increased and the frequency and amplitude of EEG were significantly reduced in 1-day traumatic group(P<0.05); The waves were decreased and the frequency and amplitude of EEG were significantly increased in 3-day traumatic group(P<0.05). There was no significant difference compared with the control group. The δ waves were decreased in 7-day and 14-day traumatic group and the frequency and amplitude of EEG were significantly increased (P<0.05). The indexes in the 28-day traumatic group returned to normal. CONCLUSIONS: Occlusal trauma can change the EEG of the rat during sleep. It mainly affects the deep sleep, and reduces sleep quality. Supported by Innovation Fund of Shandong University (2010GN048).

Investigation of morphological change of green tea polysaccharides by SEM and AFM.

The objective of this study is to investigate the morphological structure and its change of green tea polysaccharides (GTPS) before and after enzyme reaction by scanning electron microscope (SEM) and atomic force microscope (AFM). Before enzyme reaction, with the novel sample preparation method SEM images of GTPS have obtained many branches and network structures. After enzyme reaction, the morphological structure of GTPS changed, and surface roughness increased. The microstructure of GTPS from SEM with the novel sample preparation method was in accordance with the results from AFM with the tapping mode. The results indicate that the novel sample preparation of GTPS for SEM is a simple, feasible, and reliable method for observing the surface morphology.

DsRNA-free transmissible hypovirulence associated with formation of intra-hyphal hyphae in Botrytis cinerea.

A spontaneous mutant CanBc-3HV and its parental strain CanBc-3 of Botrytis cinerea were investigated in terms of pathogenicity, colony morphology, hypovirulence transmissibility, presence of double-stranded RNA (dsRNA), and formation of intra-hyphal hyphae (IH). Results showed that inoculation of CanBc-3HV on detached leaves of Brassica napus did not produce any visible necrotic lesions (20°C, 72h), whereas inoculation of CanBc-3 caused necrotic leaf lesions. Compared to CanBc-3, CanBc-3HV grew slowly, formed numerous mycelial sectors, sporulated sporadically and failed to produce sclerotia on potato dextrose agar (PDA) (20°C, 15d). Hypovirulence and the abnormal cultural characteristics of CanBc-3HV were transmissible from CanBc-3HV to CanBc-3 in pair cultures on PDA. However, the transmission was unsuccessful from CanBc-3HV to another virulent strain CanBc-2 of B. cinerea. These results suggest that transmission of the hypovirulence and the abnormal cultural characteristics of CanBc-3HV are strain-specific. No dsRNA was detected in mycelia of either CanBc-3HV or CanBc-3, implying that the hypovirulence of CanBc-3HV is caused by a transmissible element (TE) of non-RNA mycoviral origin. Formation of IH through self-infection was observed in CanBc-3HV, CanBc-3T1 (a hypovirulent derivative of CanBc-3 trans-infected by TE in CanBc-3HV), but was not observed in CanBc-3, suggesting that IH formation is associated with the hypovirulence of CanBc-3HV. To our knowledge, this is the first report of dsRNA-free transmissible hypovirulence associated with IH formation in B. cinerea.