Deoxynivalenol triggers mitotic catastrophe and apoptosis in C2C12 myoblasts.

Deoxynivalenol (DON), commonly known as vomitoxin, is a mycotoxin produced by fungi and is frequently found as a contaminant in various cereal-based food worldwide. While the harmful effects of DON have been extensively studied in different tissues, its specific impact on the proliferation of skeletal muscle cells remains unclear. In this study, we utilized murine C2C12 myoblasts as a model to explore the influence of DON on their proliferation. Our observations indicated that DON exhibits dose-dependent toxicity, significantly inhibiting the proliferation of C2C12 cells. Through the application of RNA-seq analysis combined with gene set enrichment analysis, we identified a noteworthy downregulation of genes linked to the extracellular matrix (ECM) and condensed chromosome. Concurrently with the reduced expression of ECM genes, immunostaining analysis revealed notable changes in the distribution of fibronectin, a vital ECM component, condensing into clusters and punctate formations. Remarkably, the exposure to DON induced the formation of multipolar spindles, leading to the disruption of the normal cell cycle. This, in turn, activated the p53-p21 signaling pathway and ultimately resulted in apoptosis. These findings contribute significant insights into the mechanisms through which DON induces toxicity within skeletal muscle cells.

SRSF1 Is Required for Mitochondrial Homeostasis and Thermogenic Function in Brown Adipocytes Through its Control of Ndufs3 Splicing.

RNA splicing dysregulation and the involvement of specific splicing factors are emerging as common factors in both obesity and metabolic disorders. The study provides compelling evidence that the absence of the splicing factor SRSF1 in mature adipocytes results in whitening of brown adipocyte tissue (BAT) and impaired thermogenesis, along with the inhibition of white adipose tissue browning in mice. Combining single-nucleus RNA sequencing with transmission electron microscopy, it is observed that the transformation of BAT cell types is associated with dysfunctional mitochondria, and SRSF1 deficiency leads to degenerated and fragmented mitochondria within BAT. The results demonstrate that SRSF1 effectively binds to constitutive exon 6 of Ndufs3 pre-mRNA and promotes its inclusion. Conversely, the deficiency of SRSF1 results in impaired splicing of Ndufs3, leading to reduced levels of functional proteins that are essential for mitochondrial complex I assembly and activity. Consequently, this deficiency disrupts mitochondrial integrity, ultimately compromising the thermogenic capacity of BAT. These findings illuminate a novel role for SRSF1 in influencing mitochondrial function and BAT thermogenesis through its regulation of Ndufs3 splicing within BAT.

Gastric cancer metastasis-related NT5DC2 indicates unfavorable prognosis of patients.

PURPOSE: Approximately 80 to 90% of patients with gastric cancer (GC) eventually develop into metastatic GC nowadays,because GC is difficult to be diagnosed at an early stage. GC patients with metastases typically have a poor prognosis. It is necessary to explore a potential prognostic marker in metastatic GC. METHODS: All GC data were obtained from The Cancer Genome Atlas and Gene Expression Omnibus databases. The metastasis-related candidate gene and its role in GC were analyzed by comprehensive analysis. RESULTS: Totally 1049 metastasis-related genes were identified in GC. Univariate Cox regression analysis screened the top 10 genes (PDHX, SLC43A1, CSAG2, NT5DC2, CSAG1, FMN1, MED1, HIVEP2, FNDC3A, and PPP1R2) that were closely correlated with prognosis of GC patients. Among which, NT5DC2 was screened as the target gene for subsequent study. The NT5DC2 expression were increased in primary GC and metastatic GC samples. Moreover, GC patients with high NT5DC2 expression exhibited shorter overall survival and post progression survival, and the NT5DC2 was metastatic GC patients' independent prognostic factor. Totally 29 pathways were activated in metastatic GC samples with high NT5DC2 expression. Four immune cells' infiltration were significantly different between NT5DC2 high and low expressed metastatic GC patients. NT5DC2 showed significantly negative correlations with 6 types of immune cells' critical marker genes and 5 types of immune cell infiltration. The 10 immune checkpoint expressions were decreased in high NTDC2 expression metastatic GC patients. CONCLUSIONS: NT5DC2 plays a prognostic role in metastatic GC. GC patients with high NT5DC2 expression indicates unfavorable prognosis.

High TXNIP expression accelerates the migration and invasion of the GDM placenta trophoblast.

INTRODUCTION: Our previous study has proofed the glucose sensitive gene-thioredoxin-interacting protein (TXNIP) expression was up in the placenta of the patients with gestational diabetes mellitus (GDM), but the pathological mechanisms underlying abnormal TXNIP expression in the placenta of patients with GDM is completely unclear and additional investigations are required to explain the findings we have observed. In the present study, we simulated the high TXNIP expression via introducing the Tet-On "switch" in vitro, approximate to its expression level in the real world, to explore the following consequence of the abnormal TXNIP. METHODS: The expression and localization of TXNIP in the placenta of GDM patients and the health control was investigated via immunofluorescent staining, western blot and RT-qPCR. Overexpression of TXNIP was achieved through transfecting Tet-on system to the human trophoblastic cell line-HTR-8/Svneo cell. TXNIP knockout was obtained via CRISPR-Cas9 method. The cell phenotype was observed via IncuCyte Imaging System and flow cytometry. The mechanism was explored via western blot and RT-qPCR. RESULTS: The expression level of TXNIP in the GDM placenta was nearly 2-3 times higher than that in the control. The TXNIP located at trophoblastic cells of the placenta. When the expression of TXNIP was upregulated, the migration and invasion of the cells accelerated, but cell apoptosis and proliferation did not changed compared with the control group. Furthermore, the size of the TetTXNIP cells became larger, and the expression level of Vimentin and p-STAT3 increased in the TetTXNIP cells. All the changes mentioned above were opposite in the TXNIP-KO cells. CONCLUSIONS: Abnormal expression of TXNIP might be related to the impairment of the GDM placental function, affecting the migration and invasion of the placental trophoblast cells through STAT3 and Vimentin related pathway; thus, TXNIP might be the potential therapeutic target for repairing the placental dysfunction deficient in GDM patients.

Exclusion of NUMB Exon12 Controls Cancer Cell Migration through Regulation of Notch1-SMAD3 Crosstalk.

NUMB is an endocytic adaptor protein that contains four isoforms (p65, p66, p71 and p72) due to alternative splicing regulation. Here, we show that NUMB exon12 (E12)-skipping isoforms p65/p66 promote epithelial to mesenchymal transition (EMT) and cancer cell migration in vitro, and facilitate cancer metastasis in mice, whereas E12-included p71/p72 isoforms attenuate these effects. Mechanistically, p65/p66 isoforms significantly increase the sorting of Notch1 through early endosomes (EEs) for enhanced Notch1 activity. In contrast, p71/p72 isoforms act as negative regulators of Notch1 by ubiquitylating the Notch1 intracellular domain (N1ICD) and promoting its degradation. Moreover, we observed that the interaction between N1ICD and SMAD3 is important for their own stabilization, and for NUMB-mediated EMT response and cell migration. Either N1ICD or SMAD3 overexpression could significantly recuse the migration reduction seen in the p65/p66 knockdown, and Notch1 or SMAD3 knockdown rescued the migration advantage seen in the overexpression of p66. Taken all together, our study provides mechanistic insights into the opposite regulation of Notch1-SMAD3 crosstalk by NUMB isoforms and identifies them as critical regulators of EMT and cancer cell migration.

Single-Cell RNA Sequencing Reveals Heterogeneity of Myf5-Derived Cells and Altered Myogenic Fate in the Absence of SRSF2.

Splicing factor SRSF2 acts as a critical regulator for cell survival, however, it remains unknown whether SRSF2 is involved in myoblast proliferation and myogenesis. Here, knockdown of SRSF2 in myoblasts causes high rates of apoptosis and defective differentiation. Combined conditional knockout and lineage tracing approaches show that Myf5-cre mice lacking SRSF2 die immediately at birth and exhibit a complete absence of mature myofibers. Mutant Myf5-derived cells (tdtomato-positive cells) are randomly scattered in the myogenic and non-myogenic regions, indicating loss of the community effect required for skeletal muscle differentiation. Single-cell RNA-sequencing reveals high heterogeneity of myf5-derived cells and non-myogenic cells are significantly increased at the expense of skeletal muscle cells in the absence of SRSF2, reflecting altered cell fate. SRSF2 is demonstrated to regulate the entry of Myf5 cells into the myogenic program and ensures their survival by preventing precocious differentiation and apoptosis. In summary, SRSF2 functions as an essential regulator for Myf5-derived cells to respond correctly to positional cues and to adopt their myogenic fate.

Whole-mount Staining of Mouse Diaphragm Neuromuscular Junctions.

The neuromuscular junction (NMJ) is a specialized synapse that connects the terminal end of a motor neuron and a skeletal muscle fiber. Defects in NMJ cause abnormalities of neuromuscular transmission, leading to NMJ disorders. The mammalian diaphragm muscle is essential for respiration and has been widely used to study NMJ formation. Here, we provide a simple and straightforward protocol for preparing diaphragms from embryonic, neonatal, and adult mice and for subsequent NMJ staining.

Splicing Factor SRSF1 Is Essential for Satellite Cell Proliferation and Postnatal Maturation of Neuromuscular Junctions in Mice.

Satellite cells are main muscle stem cells that could provide myonuclei for myofiber growth and synaptic-specific gene expression during the early postnatal development. Here, we observed that splicing factor SRSF1 is highly expressed in myoblasts and its expression is closely related with satellite cell activation and proliferation. By genetic deletion of SRSF1 in myogenic progenitors, we found that SRSF1 is critical for satellite cell proliferation in vitro and in vivo. Most notably we also observed that SRSF1 is required for the functional neuromuscular junction (NMJ) formation, as SRSF1-deficient mice fail to form mature pretzel-like NMJs, which leads to muscle weakness and premature death in mice. Finally, we demonstrated that SRSF1 contributes to muscle innervation and muscle development likely by regulating a restricted set of tissue-specific alternative splicing events. Thus, our data define a unique role for SRSF1 in postnatal skeletal muscle growth and function in mice.

[Experimental study of the effect of the sciatic nerve elongation on pain in rats].

OBJECTIVE: To investigate the effect of the sciatic nerve elongation on pain in rats. METHODS: Thirty-six adult male Wistar rats of SPF grade, weighing 250-300 g. Eighteen of them were randomly divided into 3 groups, 6 rats in each group. They were sciatic nerve elongation group (group A), nerve no-elongation group (group B), and nerve ligation group (group C). The model of 10-mm sciatic nerve defect was established in all 3 groups. The sciatic nerve was extended at a speed of 1 mm/d for 14 days in group A. The group B was only installed with external fixation. The nerve stumps were ligated in the group C. At 3, 7, 10, and 14 days after operation, the foot injury was evaluated by the autotomy scoring scale. At 14 days after operation, the dorsal root ganglia (DRG) of L 4-S 1 spinal cord of rats in each group was observed by tumor necrosis factor α (TNF-α) immunohistochemical staining, and the primary antibodies were replaced by pure serum as negative control group. Another 18 rats were randomly divided into 3 groups, 6 rats in each group. They were sciatic nerve elongation group (group A1), nerve no-elongation group (group B1), positive control group (group C1). In groups A1 and B1, the 10-mm long sciatic nerve defect model was established by the same method as groups A and B, and then fixed with external fixation. Nerve elongation was done or not done without anesthesia at 3 days after operation. In group C1, no modeling was done and 20 µL 2.5% formaldehyde was injected into the toes. After 90 minutes, the dorsal horn of spinal cord of L 4-S 1 segment of rats was cutting for c-Fos immunohistochemical staining and the number of positive cells was counted. Primary antibodies were replaced with pure serum as negative control group. RESULTS: The autotomy scores of rats in groups B and C gradually increased postoperatively, and group A remained stable at 0.25±0.50. The scores of group C were significantly higher than those of group A and group B at each time point postoperatively ( P<0.05). The scores of group A were significantly lower than those of group B at 10 and 14 days postoperatively ( P<0.05). TNF-α immunohistochemical staining showed that the TNF-α expression in group A was weak, slightly positive (+/-); in group B was positive (+); in group C was strongly positive (++); and the negative control group had no TNF-α expression (-). c-Fos immunohistochemical staining showed that the c-Fos expressions in groups A1 and B1 were weak positive, in group C1 was strong positive, and negative control group had no c-Fos positive expression. The number of c-Fos positive cells in groups A1, B1, C1, and negative control group were (21.5±6.6), (19.3±8.1), (95.6±7.4), and 0 cells/field, respectively, and group C1 was significantly higher than groups A1 and B1 ( P<0.05), there was no significant difference between group A1 and group B1 ( P>0.05). CONCLUSION: Nerve elongation does not cause obvious pain neither during the operation of elongation nor throughout the whole elongation.