Fibulin-5 protects the extracellular matrix of chondrocytes by inhibiting the Wnt/β-catenin signaling pathway and relieves osteoarthritis

YY1 affects the levels and function of fibulin‑5 in ox‑LDL‑treated vascular smooth muscle cells

Fibulin-5 is reportedly involved in the pathological process of atherosclerosis (AS) where low expression has been frequently observed in ruptured atherosclerotic plaques. The aim of the present study was to determine the effects of fibulin-5 on the responses of vascular smooth muscle cells (VSMC) to oxidized low-density lipoprotein (ox-LDL). The expression of fibulin-5 was studied in human aortic-VSMCs (HA-VSMCs) treated with ox-LDL. Fibulin-5 was first overexpressed by the transfection of Ov-Fibulin-5 plasmids in HA-VSMCs challenged with ox-LDL to investigate its influence on cell proliferation, migration and invasion using Cell Counting Kit-8, wound healing and Transwell assays. Yin Yang-1 (YY1) was bioinformatically predicted to bind to the promoter sites of fibulin-5, which was subsequently confirmed by dual-luciferase reporter gene assay. Fibulin-5 overexpression was able to suppress cell proliferation, invasion and migration, which was effectively reversed by YY1 silencing by the transfection of siRNA-Fibulin-5 plasmids which could induced fibulin-5 silencing. YY1 binding sites in the promoter region of fibulin-5 were identified and confirmed in vitro by chromatin immunoprecipitation assay and dual-luciferase reporter gene assay. The present results suggested that as a modulator of fibulin-5, YY1 alleviated ox-LDL-induced proliferation, invasion, migration and phenotypic transition from differentiated contractile phenotype to dedifferentiated phenotype in VSMCs. However, the mechanism underlying the YY1-mediated regulation of fibulin-5 expression needs to be confirmed further in vivo. Nevertheless, targeting fibulin-5 and YY1 could be further developed for AS therapy.

Upregulation of PTK7 and β-catenin after vaginal mechanical dilatation: an examination of fibulin-5 knockout mice

INTRODUCTION AND HYPOTHESIS

Pelvic organ prolapse (POP) in women is associated with deficiency of elastic fibers, and fibulin-5 is known to be a critical protein in the synthesis of elastin. The purpose of this study is to investigate the related pathway for the synthesis of elastin via fibulin-5 using fibulin-5 knockout mice.

METHODS

Fibulin-5 knockout mice were generated using the CRISPR/Cas9 system, and vaginal dilatation was used to mimic vaginal delivery. We divided the mice into three groups: Fbln5^+/+ mice immediately after dilatation (Fbln5^+/+ day0), Fbln5^+/+ mice 3 days after dilatation (Fbln5^+/+ day3) and Fbln5^-/- mice 3 days after dilatation (Fbln5^-/- day3). Proteins related to elastogenesis in the vaginal wall were measured by liquid chromatography mass spectrometry (LC-MS/MS) analysis, and differences in the expression of these proteins between the Fbln5^-/- mice and the Fbln5^+/+ mice were analyzed using western blotting.

RESULTS

In the LC-MS/MS analysis, protein tyrosine kinase 7 (PTK7) was not detected in the Fbln5^-/- day3 group, although the expression increased by > 1.5 times between the Fbln5^+/+ day0 and day3 groups. PTK7 and β-catenin are known to act in the Wnt/β-catenin pathway, and both were upregulated after dilatation in the Fbln5^+/+ mice, though not in the Fbln5^-/- mice.

CONCLUSION

Our findings suggest that these proteins are involved in elastogenesis via fibulin-5, and the impairment of these proteins might be the underlying cause of POP manifestation.

Exosome-Encapsulated microRNA-127-3p Released from Bone Marrow-Derived Mesenchymal Stem Cells Alleviates Osteoarthritis Through Regulating CDH11-Mediated Wnt/β-Catenin Pathway

Objective

Exosome-encapsulated microRNAs (miRNAs) are being considered as either diagnostic or predictive markers in different types of diseases. Here, we discussed the effects of exosome-encapsulated miR-127-3p from bone marrow-derived mesenchymal stem cells (BM-MSCs) on osteoarthritis (OA).

Methods

BM-MSCs and primary chondrocytes were isolated from Sprague Dawley rats. IL-1β was utilized to treat chondrocytes to mimic an OA in vitro model, and exosomes extracted from BM-MSCs were utilized to treat chondrocytes so as to verify their protective effects on OA. Through online website prediction and experiments confirmation, we found the most significantly enriched miRNA in exosomes and elucidated the effect of this miRNA on the therapeutic effect of exosomes by interfering with its expression. Also, the genes targeted by the miRNA and the involved pathway were also found through bioinformatics analysis and experimental research, thereby probing into the protective mechanism of exosomes on chondrocytes.

Results

Exosomes derived from BM-MSCs restricted the IL-1β-induced chondrocytes damage. miR-127-3p was found to be enriched in exosomes, and the protective effect of exosomes was reversed by miR-127-3p inhibition. miR-127-3p targeted CDH11, and overexpressed CDH11 in chondrocytes weakened the therapeutic effect of exosomes. IL-1β treatment resulted in the activation of the Wnt/β-catenin pathway in chondrocytes. Exosomes treatment could inhibit the activation of this pathway, and overexpressed CDH11 reversed the inhibitory effect of exosomes on this pathway.

Conclusion

This study suggests that exosomal miR-127-3p derived from BM-MSCs inhibits CDH11 in chondrocytes, thereby blocking the Wnt/β-catenin pathway activation and relieving chondrocyte damage in OA.