Inhibition of PRMT1 alleviates sepsis-induced acute kidney injury in mice by blocking the TGF-β1 and IL-6 trans-signaling pathways

Identification of potential hub genes and drugs in septic kidney injury: a bioinformatic analysis with preliminary experimental validation

Background

Sepsis-associated kidney injury (SAKI) is a prevalent complication in intensive care unit (ICU) patients with sepsis. Diagnosis currently relies on clinical assessment, urine output, and serum creatinine levels, yet effective clinical treatments remain scarce. Our objectives are to explore prospective, targeted medications for the treatment of septic kidney injury and to employ bioinformatics to identify key genes and pathways that may be implicated in the pathogenesis of SAKI.

Methods

We utilized the GEO database for differential gene screening. Related genes of septic kidney injury were identified through Pubmed2Ensembl, followed by annotation and visualization of gene ontology biological processes and KEGG pathways using DAVID. Protein-protein interactions were analyzed with the STRING database, and hub genes were identified using Cytoscape software. Candidate genes were further validated through Metascape. The CTD database was employed to uncover the relationship between hub genes and acute kidney injury (AKI). CIBERSORT was applied to evaluate the infiltration of immune cells and their association with hub genes. Hub genes were experimentally verified through qPCR detection. Lastly, the Drug-Gene Interaction Database (DGIdb) was utilized to identify drug-gene interactions.

Results

Six genes, including TNF, CXCL8, IL-6, IL-1β, IL-2, and IL-10, were associated with three major signaling pathways: the COVID-19 adverse outcome pathway, an overview of pro-inflammatory and pro-fibrotic mediators, and the interleukin-10 signaling pathway. Additionally, 12 targeted drugs were identified as potential therapeutic agents.

Arginine methyltransferase PRMT1 promotes ferroptosis through EGR1/GLS2 axis in sepsis-related acute lung injury

Acute lung injury (ALI), a frequent and severe complication of sepsis, is associated with significant mortality rates. Previous studies indicated that GLS2 plays a key role in promoting ferroptosis. However, its underlying mechanisms remain unclear. Here we show, there were elevated ferroptosis and increased expression levels of protein arginine methyltransferase 1 (PRMT1), early growth response 1 (EGR1), and glutaminase 2 (GLS2) in both in vitro and in vivo ALI models. Additionally, EGR1 was found to induce the transcription of GLS2, thereby promoting ferroptosis. We also discovered that the protein level of EGR1 was increased through enhanced stability, facilitated by PRMT1-mediated arginine methylation, and reduced ubiquitination degradation regulated by neural precursor cell expressed developmentally down-regulated protein 4 like (NEDD4L). The in vivo results confirmed that the knockdown of PRMT1 suppressed ferroptosis via the EGR1/GLS2 axis. Our findings suggest that PRMT1-mediated stabilization of EGR1 promoted sepsis induced ALI via GLS2, highlighting the therapeutic potential of targeting PRMT1 or EGR1 in the treatment of sepsis-induced ALI.

PRMT1-mediated BRD4 arginine methylation and phosphorylation promote partial epithelial-mesenchymal transformation and renal fibrosis

Bromodomain-containing protein 4 (BRD4) plays a vital role in fibrosis of various organs. However, the underlying mechanism of BRD4 in renal fibrosis remains unclear. To construct in vitro and in vivo models of renal fibrosis, TCMK-1 cells were subjected to TGF-β1 treatment and mice were subjected to UUO surgery and adenine induction. IP assay was used for arginine asymmetric dimethylation (ADMA) level, ubiquitination degradation of Snail, and acetylation level of Snail test. Co-IP was used to validate the interactions of BRD4, protein arginine methyltransferase-1 (PRMT1), and Snail. HE staining and Masson staining were used for morphological examination of renal tissue. BRD4 was abnormally overexpressed during renal fibrosis. TGF-β1-induced fibrosis and partial epithelial-mesenchymal transition (pEMT) could be inhibited by BRD4 silencing. PRMT1 mediated ADMA level of BRD4 to enhance BRD4 phosphorylation and its protein stability. Snail protein degradation was attenuated by BRD4 overexpression in an acetylation-dependent manner in TCMK-1 cells. Furthermore, PRMT1 inhibitor abolished BRD4 overexpression-induced fibrosis and pEMT in TGF-β1-treated TCMK-1 cells and Snail overexpression reversed BRD4 silencing-induced inhibition of fibrosis and pEMT. What's more, the reduction of BRD4 arginine methylation inhibited BRD4 phosphorylation and Snail expression to alleviate renal fibrosis in UUO surgery and adenine induction mice. Collectively, PRMT1-mediated BRD4 arginine methylation and phosphorylation promoted pEMT and renal fibrosis through regulation of Snail expression.

Serum inflammation-related proteins in a acute compartment syndrome rat model

We aim to explore variations of serum inflammation-related proteins in an acute compartment syndrome (ACS) rat model. We collected serum from 25 healthy Sprague-Dawley rats (control group, CG) and 50 rats with tibial fractures, including 25 rats with ACS (ACS group, AG), and 25 rats without ACS (fracture group, FG). Ten samples per group were randomly chosen for proximity extension assay analysis of 92 inflammation-related proteins, and all samples were verified by enzyme-linked immunosorbent assays. Receiver-operating characteristic curve analysis was used to identify the diagnostic ability and cut-off values. Our findings showed that the levels of Il6 and Prdx5 in the FG and Il6, Prdx5, Dctn2, and Plin1 in the AG, were significantly higher than those in the CG. Notably, compared with the FG, high expression of Prdx5, Dctn2, and Plin1 was observed in the AG. Additionally, we identified 58.8764, 14.023, and 31.8730 pg/ml as the cut-off values of Prdx5, Dctn2, and Plin1 to predict ACS in rats. Similarly, the cut-off values of Il6, Prdx5, Dctn2, and Plin1 to predict ACS in healthy rats were 10.6783, 766.5879, 12.5627, and 14.3623 pg/ml, respectively. Furthermore, the combination of these proteins had the highest diagnostic accuracy. We identified Prdx5, Dctn2, and Plin1 as potential biomarkers of ACS compared with fracture in rats and revealed that combination of Il6, Prdx5, Dctn2, and Plin1 had the highest diagnostic accuracy to predict ACS compared with the healthy condition. Furthermore, the cut-off values for these biomarkers were determined, providing a new method to rapidly assess the risk of ACS and manage early targeted interventions.

EGR3 reduces podocyte inflammatory damage in obesity related glomerulopathy by inhibiting the PRMT1pSTAT3 pathway

OBJECTIVES

Obesity related glomerulopathy (ORG) is induced by obesity, but the pathogenesis remains unclear. This study aims to investigate the expression of early growth response protein 3 (EGR3) in the renal cortex tissues of ORG patients and high-fat diet-induced obese mice, and to further explore the molecular mechanism of EGR3 in inhibiting palmitic acid (PA) induced human podocyte inflammatory damage.

METHODS

Renal cortex tissues were collected from ORG patients (n=6) who have been excluded from kidney damage caused by other diseases and confirmed by histopathology, and from obese mice induced by high-fat diet (n=10). Human and mouse podocytes were intervened with 150 μmol/L PA for 48 hours. EGR3 was overexpressed or silenced in human podocytes. Enzyme linked immunosorbent assay (ELISA) was used to detcet the levels of interleukin-6 (IL-6) and interleukin-1β (IL-1β). Real-time RT-PCR was used to detect the mRNA expressions of EGR3, podocytes molecular markers nephrosis 1 (NPHS1), nephrosis 2 (NPHS2), podocalyxin (PODXL), and podoplanin (PDPN). RNA-seq was performed to detect differentially expressed genes (DEGs) after human podocytes overexpressing EGR3 and treated with 150 μmol/L PA compared with the control group. Co-immunoprecipitation (Co-IP) combined with liquid chromatography tandem mass spectrometry (LC-MS) was used to detect potential interacting proteins of EGR3 and the intersected with the RNA-seq results. Co-IP confirmed the interaction between EGR3 and protein arginine methyltransferases 1 (PRMT1), after silencing EGR3 and PRMT1 inhibitor intervention, the secretion of IL-6 and IL-1β in PA-induced podocytes was detected. Western blotting was used to detect the expression of phosphorylated signal transducer and activator of transcription 3 (p-STAT3) after overexpression or silencing of EGR3.

RESULTS

EGR3 was significantly upregulated in renal cortex tissues of ORG patients and high-fat diet-induced obese mice (both P<0.01). In addition, after treating with 150 μmol/L PA for 48 hours, the expression of EGR3 in human and mouse podocytes was significantly upregulated (both P<0.05). Overexpression or silencing of EGR3 in human podocytes inhibited or promoted the secretion of IL-6 and IL-1β in the cell culture supernatant after PA intervention, respectively, and upregulated or downregulated the expression of NPHS1, PODXL, NPHS2,and PDPN (all P<0.05). RNA-seq showed a total of 988 DEGs, and Co-IP+LC-MS identified a total of 238 proteins that may interact with EGR3. Co-IP confirmed that PRMT1 was an interacting protein with EGR3. Furthermore, PRMT1 inhibitors could partially reduce PA-induced IL-6 and IL-1β secretion after EGR3 silencing in human podocytes (both P<0.05). Overexpression or silencing of EGR3 negatively regulated the expression of PRMT1 and p-STAT3.

CONCLUSIONS

EGR3 may reduce ORG podocyte inflammatory damage by inhibiting the PRMT1/p-STAT3 pathway.

Olink proteomics analysis uncovers the landscape of inflammation-related proteins in patients with acute compartment syndrome

PURPOSE

Our primary purpose was to explore the landscape of inflammation-related proteins, and our second goal was to investigate these proteins as potential biomarkers of acute compartment syndrome (ACS), which is a serious complication of tibial fractures.

METHODS

We collected sera from 15 healthy subjects (control group, CG) and 30 patients with tibial fractures on admission day, comprising 15 patients with ACS (ACS group, AG) and 15 patients without ACS (fracture group, FG). Ten samples in each group were analyzed by the inflammation panel of Olink Proteomics Analysis, and all samples were verified by an ELISA. Receiver-operating characteristic (ROC) curve analysis was performed to identify the diagnostic ability and cutoff values of potential biomarkers.

RESULTS

Our findings showed that the levels of IL6, CSF-1, and HGF in the FG were significantly higher than those in the CG. Similar results were found between the AG and CG, and their cutoff values for predicting ACS compared with the CG were 9.225 pg/ml, 81.04 pg/ml, and 0.3301 ng/ml, respectively. Furthermore, their combination had the highest diagnostic accuracy. Notably, compared with FG, we only found a higher expression of CCL23 in the AG. Additionally, we identified 35.75 pg/ml as the cutoff value of CCL23 for predicting ACS in patients with tibial fractures.

CONCLUSION

We identified CCL23 as a potential biomarker of ACS in comparison with tibial fracture patients and the significance of the combined diagnosis of IL6, CSF-1, and HGF for predicting ACS compared with healthy individuals. Furthermore, we also found their cutoff values, providing clinicians with a new method for rapidly diagnosing ACS. However, we need larger samples to verify our results.