SNIP1 reduces extracellular matrix degradation and inflammation via inhibiting the NF-κB signaling pathway in osteoarthritis

CDK5 Upregulated by ELF3 Transcription Promotes IL-1β-induced Inflammation and Extracellular Matrix Degradation in Human Chondrocytes

Osteoarthritis (OA) is a common chronic disease with age-associated increase in both incidence and prevalence. The cyclin-dependent kinase 5 (CDK5), which is a member of the CDK family, is involved in many chronic diseases. This study was performed to explore the functional role of CDK5 in OA and to discuss the detailed molecular mechanisms. The expressions of CDK5 and ELF3 before or after transfection were detected with reverse transcription-quantitative PCR (RT-qPCR) and western blot. 5-ethynyl-2'-deoxyuridine (Edu) and terminal deoxynucleoitidyl transferase-mediated nick-end labeling (TUNEL) assays were used to detect the proliferation and apoptosis of C28/I2 cells. The levels of inflammatory cytokines were estimated using enzyme-linked immunosorbent assay (ELISA) while the expressions of proteins implicated in extracellular matrix (ECM) degradation- and apoptosis were detected using western blot. Additionally, the activity of CDK5 promoters and its binding with ELF3 were detected using luciferase activity assay and chromatin immunoprecipitation (CHIP) assay. In the present study, it was discovered that the mRNA and protein expressions of CDK5 were significantly increased in IL-1β-induced C28/I2 cells. After depleting CDK5 expression, the apoptosis, inflammation and ECM in C28/I2 cells with IL-1β induction were suppressed. It was also found that ELF3 expression was increased in IL-1β-induced C28/I2 cells and acted as a transcription factor binding to the CDK5 promoter to regulate its transcriptional expression. The further experiments evidenced that ELF3 overexpression partially reversed the inhibitory effects of CDK5 deficiency on IL-1β-induced apoptosis, inflammation and ECM in C28/I2 cells. Collectively, CDK5 that upregulated by ELF3 transcription could promote the development of OA.

MSRB2 Ameliorates H2O2-induced Chondrocyte Oxidative Stress and Suppresses Apoptosis in Osteoarthritis

BACKGROUND

Chondrocyte oxidative stress and apoptosis are critical factors contributing to the pathogenesis of osteoarthritis (OA). Methionine sulfoxide reductase B2 (MSRB2) is a mitochondrial protein that protects cells from oxidative stress and is involved in apoptosis. This study aimed to investigated the expression of MSRB2 in articular cartilage tissues and elucidated its effect on H2O2-stimulated chondrocytes.

METHODS

Human chondrocytes were cultured in Dulbecco's modified Eagle's medium (DMEM)/F12. MSRB2 overexpression in chondrocytes was achieved by transfecting with an MSRB2 overexpression plasmid. Western blot, quantitative RT-PCR, Immunofluorescence staining, and TUNEL assay were employed in this study.

RESULTS

MSRB2 expression was found to be reduced in OA patients. Furthermore, overexpression of MSRB2 in H2O2-induced chondrocytes mitigated apoptosis and enhanced cell viability. Elevated MSRB2 expression diminished chondrocyte ROS contents, decreased cytochrome C (Cyc) in the cytoplasm, and regulated mitochondrial membrane potential to maintain mitochondrial homeostasis. Interestingly, knockdown of charged multivesicular body protein 5 (CHMP5) led to a decreased inMSRB2 expression in chondrocytes. Additionally, protein levels of CHMP5 and MSRB2 were reduced in H2O2-stimulated chondrocytes, and silencing CHMP5 reduced MSRB2 expression. Knockdown of CHMP5 increased cleaved caspase-3 expression in H2O2-induced chondrocytes and elevated TUNEL-positive chondrocytes.

CONCLUSION

MSRB2 decreased in OA, and overexpression of MSRB2 alleviated oxidative stress and apoptosis of chondrocyte.

LncRNA MSC-AS1 regulates SNIP1 SUMOylation-mediated EMT by binding to SENP1 to promote intestinal fibrosis in Crohn's disease

As a common complication of Crohn's disease (CD), the mechanism underlying CD intestinal fibrosis remains unclear. Studies have shown that epithelial-mesenchymal transition (EMT) is a key step in the development of intestinal fibrosis in CD. It is currently known that the long non-coding RNA (lncRNA) MSC-AS1 plays an important role in regulating the secretion of inflammatory mediators and EMT; however, its role in intestinal fibrosis remains unclear. MSC-AS1 was significantly upregulated in the CD intestinal tissue and intestinal tissue of mice treated with 2,4,6-trinitrobenzenesulfonic acid. Downregulation of its expression can inhibit EMT and alleviates intestinal fibrosis by regulating SNIP1. In addition, MSC-AS1 directly interacted with SENP1, blocking the deSUMOylation of SNIP1 and inhibiting its activity. Furthermore, we found that SENP1 enhanced the expression of SNIP1 and reduced intestinal fibrosis. In summary, MSC-AS1 regulates EMT through the SENP1/SNIP1 axis to promote fibrosis, and may be considered a potential molecular target for the treatment of CD and intestinal fibrosis.

The clinical utilization of SNIP1 and its pathophysiological mechanisms in disease

Smad intranuclear binding protein 1 (SNIP1), a highly conserved nuclear protein, functions as a transcriptional regulator and exerts a significant influence on disease progression. In addition, the N-terminal domain of SNIP1 facilitates its interaction with Smad4, a signaling protein associated with the TGF-β family, and RelA/p65, a transcription factor connected to NF-κB. This interaction further enhances the transcriptional activation of c-Myc-dependent genes. Presently, the primary emphasis in research is directed towards targeting the catalytic domain of SNIP1, as it holds promise as a potential therapeutic target for various diseases. While the significance of SNIP1 in pathological mechanisms remains uncertain, this review aims to comprehensively examine the existing literature on the association between SNIP1 and proteins implicated in the regulation of diverse clinical conditions, including cancer, inflammation, and related diseases.