Stomatin promotes neutrophil degranulation and vascular leakage in the early stage after severe burn via enhancement of the intracellular binding of neutrophil primary granules to F-actin

BACKGROUND

The pathophysiology of severe burn injuries in the early stages involves complex emergency responses, inflammatory reactions, immune system activation, and a significant increase in vascular permeability. Neutrophils, crucial innate immune cells, undergo rapid mobilization and intricate pathophysiological changes during this period. However, the dynamic alterations and detailed mechanisms governing their biological behavior remain unclear. Stomatin protein, an essential component of the cell membrane, stabilizes and regulates the membrane and participates in cell signal transduction. Additionally, it exhibits elevated expression in various inflammatory diseases. While Stomatin expression has been observed in the cell and granule membranes of neutrophils, its potential involvement in post-activation functional regulation requires further investigation.

METHODS

Neutrophils were isolated from human peripheral blood, mouse peripheral blood, and mouse bone marrow using the magnetic bead separation method. Flow cytometry was used to assess neutrophil membrane surface markers, ROS levels, and phagocytic activity. The expression of the Stomatin gene and protein was examined using quantitative real-time polymerase chain reaction and western blotting methods, respectively. Furthermore, the enzyme-linked immunosorbent assay was used to evaluate the expression of neutrophil-derived inflammatory mediators (myeloperoxidase (MPO), neutrophil elastase (NE), and matrix metalloproteinase 9 (MMP9)) in the plasma. Images and videos of vascular leakage in mice were captured using in vivo laser confocal imaging technology, whereas in vitro confocal microscopy was used to study the localization and levels of the cytoskeleton, CD63, and Stomatin protein in neutrophils.

RESULTS

This study made the following key findings: (1) Early after severe burn, neutrophil dysfunction is present in the peripheral blood characterized by significant bone marrow mobilization, excessive degranulation, and impaired release and chemotaxis of inflammatory mediators (MPO, NE, and MMP9). (2) After burn injury, expression of both the stomatin gene and protein in neutrophils was upregulated. (3) Knockout (KO) of the stomatin gene in mice partially inhibited neutrophil excessive degranulation, potentially achieved via reduced production of primary granules and weakened binding of primary granules to the cell skeleton protein F-actin. (4) In severely burned mice, injury led to notable early-stage vascular leakage and lung damage, whereas Stomatin gene KO significantly ameliorated lung injury and vascular leakage.

CONCLUSIONS

Stomatin promotes neutrophil degranulation in the early stage of severe burn injury via increasing the production of primary granules and enhancing their binding to the cell skeleton protein F-actin in neutrophils. Consequently, this excessive degranulation results in aggravated vascular leakage and lung injury.

Proteomic analysis identifies Stomatin as a biological marker for psychological stress

Psychological stress emerges to be a common health burden in the current society for its highly related risk of mental and physical disease outcomes. However, how the quickly-adaptive stress response process connects to the long-observed organismal alterations still remains unclear. Here, we investigated the profile of circulatory extracellular vesicles (EVs) after acute stress (AS) of restraint mice by phenotypic and proteomic analyses. We surprisingly discovered that AS-EVs demonstrated significant changes in size distribution and plasma concentration compared to control group (CN) EVs. AS-EVs were further characterized by various differentially expressed proteins (DEPs) closely associated with biological, metabolic and immune regulations and were functionally important in potentially underlying multiple diseases. Notably, we first identified the lipid raft protein Stomatin as an essential biomarker expressed on the surface of AS-EVs. These findings collectively reveal that EVs are a significant function-related liquid biopsy indicator that mediate circulation alterations impinged by psychological stress, while also supporting the idea that psychological stress-associated EV-stomatin can be used as a biomarker for potentially predicting acute stress responses and monitoring psychological status. Our study will pave an avenue for implementing routine plasma EV-based theranostics in the clinic.

Dietary Selenium Deficiency Facilitated Reduced Stomatin and Phosphatidylserine Externalization, Increasing Erythrocyte Osmotic Fragility in Mice

Selenium (Se) is an essential trace element that maintains normal physiological functions in organisms. Since the discovery of glutathione peroxidase (GSH-PX), public interest in selenoproteins has gradually increased. Based on previous studies, dietary Se maintains erythrocyte homeostasis through selenoprotein-induced mediation of redox reactions. Furthermore, both the surface phosphatidylserine (PS) and intramembrane stomatin contents can be used as indicators of erythrocyte osmotic fragility. This study focused on the mechanism by which dietary Se deficiency increases erythrocyte osmotic fragility. We fed Se-deficient grain to mice for 8 weeks to establish a Se deficiency model in mice. We measured Se levels in the blood as well as the activities of antioxidant enzymes associated with selenoproteins in a Se-deficient environment. We used Western blotting, routine blood analysis, and other methods to detect red blood cell oxidative stress levels, membrane stomatin levels, and PS externalization. Fresh blood was collected to test erythrocyte osmotic fragility. The results showed that antioxidant enzyme activity was affected by dietary Se deficiency. Oxidative stress increased lipid peroxidation and the ROS content in the blood of the mice. Under such conditions, decreased PS exposure and stomatin content in the erythrocyte membrane eventually affected the structure of the erythrocyte membrane and increased erythrocyte osmotic fragility.

[Effects of stomatin protein expression on proliferation and apoptosis of lung cancer cells]

Objective: To investigate the effect of stomatin protein expression on the proliferation and apoptosis of lung cancer cells. Methods: The expressions of stomatin mRNA in human bronchial epithelial cells (HBE) and lung cancer cells (H520, A549, 95D, H460, Glc-82, 973 and H1299) were detected by Real-time PCR. Immunohistochemistry (IHC) was used to detect stomatin protein expression in 4 lung cancer tissue microarrays with 259 cases of lung cancer and adjacent normal tissues. After knocking down the expression of stomatin in A549 cells, the proliferation was detected by 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide (MTT) assay, the apoptosis was detected by flow cytometry, the expression levels of total protein kinase B (AKT) and phosphorylated AKT at Ser473 were detected by Western blot. BALB/c nude mice were used to detect the tumorigenic ability of stomatin downregulated A549 cells (3 mice) and control cells (3 mice), and the protein expressions of stomatin, Ki67 and CD31 in tumor tissues were detected by IHC. Results: The M (range) of stomatin mRNA expression level in H520, A549, 95D, H460, Glc-82, 973, H1299 and HBE cells were 2.71 (2.66), 3.55 (3.16), 0.26 (0.22), 2.08 (1.98), 0.87 (0.35), 1.72 (2.53), 1.10 (1.82) and 0.01 (0.02), respectively. The mRNA expression levels of stomatin in H520, A549 and H460 cells were higher than that of HBE cells (all P<0.05), whereas there was no statistical difference among 95D, Glc-82, 973, H1299 and HBE cells (all P>0.05). IHC of lung tissue microarrays showed that the positive rate of stomatin expression in human lung cancer tissues was 34.7% (90/259), which was significantly higher than that in adjacent normal tissues [1.9% (5/259)] (P<0.05). In stomatin positive lung cancer tissues, the M (IQR) of tumor size for lower stomatin expression tissues (67 cases) was [41.22 (2 761.50) cm], which was smaller than that of higher stomatin expression tissues [(23 cases, 57.98(1 333.50) cm) (P<0.05). After knocking down stomatin expression, the fourth day absorbance value of stomatin-downregulated A549 cells was 0.55±0.07, which was lower than that of control cells (0.79±0.16) (P=0.012). The proportion of early apoptotic cells of stomatin-downregulated A549 cells [8.83 (53.00)] was higher than that of control cells [4.17 (25.00)] (P=0.026). The Ser473 phosphorylated AKT protein expression level in stomatin-downregulated A549 cells was 0.68±0.16, which was decreased compared with control cells (1.16±0.39) (P<0.05). The M (IQR) of total AKT expression level in stomatin-downregulated A549 cells was 4.25 (17.00), without statistically significant difference from control cells [4.75 (19.00)] (P>0.05). After inoculation of stomatin-downregulated A549 cells in nude mice for 43 days, the tumor volume was (37.93±3.12) mm(3), which was significantly smaller than that of the control group [(454.04±32.39) mm(3)] (P<0.001). And the expression levels of stomatin, nuclear proliferation antigen Ki67, and platelet-endothelial cell adhesion molecule CD31 were 1.78±0.69, 5.19±3.84, and 10.77±1.67, respectively, which were all decreased compared with control group (17.52±8.76, 54.14±41.02, and 19.72±6.97, respectively) (all P<0.05). Conclusion: Stomatin promotes lung cancer cell proliferation and inhibits cell early apoptosis by regulating AKT signaling pathway.

Presynaptic MAST kinase controls opposing postsynaptic responses to convey stimulus valence in Caenorhabditis elegans

Animals need to quickly extract the valence information of sensory stimulus and assess whether the stimulus is attractive or aversive. Deciphering the molecular and circuit mechanisms that determine the stimulus valence is fundamental to understand how the nervous system generates the animal behaviors. Here we report that the AFD thermosensory neurons of C. elegans evoke in its postsynaptic AIY interneurons opposing neuronal responses that correlate with the valence of thermal stimuli. The C. elegans homologs of MAST kinase, Stomatin, and Diacylglycerol kinase function in AFD and regulate the opposing AIY responses. Our results further suggest that the alteration between excitatory and inhibitory AIY responses is mediated by controlling the balance of two opposing signals released from the AFD neurons.

Presynaptic plasticity is known to modulate the strength of synaptic transmission. However, it remains unknown whether regulation in presynaptic neurons can evoke excitatory and inhibitory postsynaptic responses. We report here that the Caenorhabditis elegans homologs of MAST kinase, Stomatin, and Diacylglycerol kinase act in a thermosensory neuron to elicit in its postsynaptic neuron an excitatory or inhibitory response that correlates with the valence of thermal stimuli. By monitoring neural activity of the valence-coding interneuron in freely behaving animals, we show that the alteration between excitatory and inhibitory responses of the interneuron is mediated by controlling the balance of two opposing signals released from the presynaptic neuron. These alternative transmissions further generate opposing behavioral outputs necessary for the navigation on thermal gradients. Our findings suggest that valence-encoding interneuronal activity is determined by a presynaptic mechanism whereby MAST kinase, Stomatin, and Diacylglycerol kinase influence presynaptic outputs.

Stomatin plays a suppressor role in non-small cell lung cancer metastasis

Objective

Metastasis is one of the key causes of high mortality in lung cancer. Aberrant DNA methylation is a common event in metastatic lung cancer. We aimed to identify new epigenetic regulation of metastasis-associated genes and characterize their effects on lung cancer progression.

Methods

We screened genes associated with non-small cell lung cancer (NSCLC) metastasis by integrating datasets from the Gene Expression Omnibus (GEO) database. We obtained epigenetic-regulated candidate genes by analyzing the expression profile of demethylation genes. By overlapping analysis, epigenetically modulated metastasis-associated genes were obtained. Kaplan-Meier plotter (KM plotter) was utilized to assess the overall survival (OS) of stomatin in lung cancer. Immunohistochemistry (IHC) was conducted to determine the association between stomatin and metastasis-associated clinical indicators. Both in vitro and in vivo assays were performed to investigate the potential role of stomatin in metastasis. The regulation mechanisms of transforming growth factor β1 (TGFβ1) on stomatin were determined by Sequenom MassARRAY quantitative methylation and western blot assays.

Results

A series of bioinformatic analyses revealed stomatin as the metastasis-associated gene regulated by DNA methylation. The KM plotter analysis showed a positive association between stomatin and the OS of lung cancer. IHC analysis indicated that the decreased stomatin expression is linked with advanced TNM stage. Loss- and gain-of-function experiments displayed that stomatin could inhibit the migration and invasion of NSCLC cells. Furthermore, TGFβ1 repressed stomatin expression during epithelial-to-mesenchymal transition (EMT). The negative correlation between stomatin and TGFβ1 was also validated in advanced stage III lung tumor samples. The underlying mechanism by which TGFβ1 inhibits stomatin is due in part to DNA methylation.

Conclusions

Our results suggest that stomatin may be a target for epigenetic regulation and can be used to prevent metastatic diseases.

Decreased expression of stomatin predicts poor prognosis in HER2-positive breast cancer

Background

Human epidermal growth factor receptor-2 (HER2) is a transmembrane tyrosine kinase receptor that is overexpressed in 25 to 30 % of human breast cancers and is preferentially localized in lipid rafts. Stomatin is a membrane protein that is absent from the erythrocyte plasma membrane in patients with congenital stomatocytosis and is the major component of the lipid raft.

Results

In a total of 68 clinical cases of HER2-positive breast cancer, the absence of stomatin expression was associated with a decreased 5-year survival (65 % vs. 93 %, p = 0.005) by survival analysis. For stage I-III HER2-positive breast cancer, the absence of stomatin expression was associated with a decreased 5-year disease-free survival (57 % vs. 81 %, p = 0.016) and was an independent prognostic factor by multivariate analysis. Negative stomatin expression predicts distant metastases in a hazard ratio of 4.0 (95 % confidence interval from 1.3 to 12.5).

Conclusions

These results may suggest that stomatin is a new prognostic indicator for HER2-positive breast cancer.