Identification and characterization of adult mouse meniscus stem/progenitor cells.

Meniscal damage is a common problem that accelerates the onset of knee osteoarthritis. Stem cell-based tissue engineering treatment approaches have shown promise in preserving meniscal tissue and restoring meniscal function. The purpose of our study was to identify meniscus-derived stem/progenitor cells (MSPCs) from mouse, a model system that allows for in vivo analysis of the mechanisms underlying meniscal injury and healing. MSPCs were isolated from murine menisci grown in explant culture and characterized for stem cell properties. Flow cytometry was used to detect the presence of surface antigens related to stem cells, and qRT-PCR was used to examine the gene expression profile of MSPCs. Major proteins associated with MSPCs were localized in the adult mouse knee using immunohistochemistry. Our data show that MSPCs have universal stem cell-like properties including clonogenicity and multi-potentiality. MSPCs expressed the mesenchymal stem cell markers CD44, Sca-1, CD90, and CD73 and when cultured had elevated levels of biglycan and collagen type I, important extracellular matrix components of adult meniscus. MSPC also expressed significant levels of Lox and Igf-1, genes associated with the embryonic meniscus. Localization studies showed staining for these same proteins in the superficial and outer zones of the adult mouse meniscus, regions thought to harbor endogenous repair cells. MSPCs represent a novel resident stem cell population in the murine meniscus. Analysis of MSPCs in mice will allow for a greater understanding of the cell biology of the meniscus, essential information for enhancing therapeutic strategies for treating knee joint injury and disease.

O-GlcNAcylation in ischemic diseases.

Protein glycosylation is an extensively studied field, with the most studied forms being oxygen or nitrogen-linked N-acetylglucosamine (O-GlcNAc or N-GlcNAc) glycosylation. Particular residues on proteins are targeted by O-GlcNAcylation, which is among the most intricate post-translational modifications. Significantly contributing to an organism's proteome, it influences numerous factors affecting protein stability, function, and subcellular localization. It also modifies the cellular function of target proteins that have crucial responsibilities in controlling pathways related to the central nervous system, cardiovascular homeostasis, and other organ functions. Under conditions of acute stress, changes in the levels of O-GlcNAcylation of these proteins may have a defensive function. Nevertheless, deviant O-GlcNAcylation nullifies this safeguard and stimulates the advancement of several ailments, the prognosis of which relies on the cellular milieu. Hence, this review provides a concise overview of the function and comprehension of O-GlcNAcylation in ischemia diseases, aiming to facilitate the discovery of new therapeutic targets for efficient treatment, particularly in patients with diabetes.

GNAS mutational analysis in differentiating fibrous dysplasia and ossifying fibroma of the jaw.

Differential diagnosis of fibrous dysplasia and ossifying fibroma may often pose problems for pathologists. The purpose of this study was to evaluate the value of mutational analysis of the GNAS gene in differentiating these two conditions. DNA samples from patients with fibrous dysplasia (n=30) and ossifying fibroma (n=21) were collected to analyze the presence of GNAS mutations at exons 8 and 9, the two previously reported hotspot regions, using polymerase chain reaction and direct sequencing. In all, 90% (27/30) of cases with fibrous dysplasia showed missense mutations of codon 201 at exon 8, with a predilection of arginine-to-histidine substitution (p.R201H, 70%) as opposed to arginine-to-cysteine substitution (p.R201C, 30%), whereas no mutation was detected at exon 9. No mutation was found in all 21 cases with ossifying fibroma. In addition, a meta-analysis of previously published reports on GNAS mutations in fibrous dysplasia and ossifying fibroma was performed to substantiate our findings. A total of 24 reports including 307 cases of fibrous dysplasia and 23 cases of ossifying fibroma were reviewed. The overall incidence of GNAS mutations in fibrous dysplasia was 86% (264/307), and the major types of mutations were also R201H (53%) and R201C (45%). No GNAS mutation was detected in all patients with ossifying fibroma. We also reported one case with uncertain diagnosis due to overlapping clinicopathological features of fibrous dysplasia and ossifying fibroma. An R201H mutation was detected in this case, thus confirming a diagnosis of fibrous dysplasia. Taken together, our findings indicate that mutational analysis of GNAS gene is a reliable adjunct to differentiate ossifying fibroma and fibrous dysplasia of the jaws.

Effects of HDAC4 on IL-1ß-induced matrix metalloproteinase expression regulated partially through the WNT3A/ß-catenin pathway.

BACKGROUND: Histone deacetylase 4 (HDAC4) regulates chondrocyte hypertrophy and bone formation. The aim of the present study was to explore the effects of HDAC4 on Interleukin 1 beta (IL-1ß)-induced chondrocyte extracellular matrix degradation and whether it is regulated through the WNT family member 3A (WNT3A)/ß-catenin signaling pathway. METHODS: Primary chondrocytes (CC) and human chondrosarcoma cells (SW1353 cells) were treated with IL-1ß and the level of HDAC4 was assayed using Western blotting. Then, HDAC4 expression in the SW1353 cells was silenced using small interfering RNA to detect the effect of HDAC4 knockdown on the levels of matrix metalloproteinase 3 (MMP3) and MMP13 induced by IL-1ß. After transfection with HDAC4 plasmids, the overexpression efficiency was examined using Real-time quantitative polymerase chain reaction (qRT-PCR) and the levels of MMP3 and MMP13 were assayed using Western blotting. After incubation with IL-1ß, the translocation of ß-catenin into the nucleus was observed using immunofluorescence staining in SW1353 cells to investigate the activation of the WNT3A/ß-catenin signaling pathway. Finally, treatment with WNT3A and transfection with glycogen synthase kinase 3 beta (GSK3ß) plasmids were assessed for their effects on HDAC4 levels using Western blotting. RESULTS: IL-1ß downregulated HDAC4 levels in chondrocytes and SW1353 cells. Furthermore, HDAC4 knockdown increased the levels of MMP3 and MMP13, which contributed to the degradation of the extracellular matrix. Overexpression of HDAC4 inhibited IL-1ß-induced increases in MMP3 and MMP13. IL-1ß upregulated the levels of WNT3A, and WNT3A reduced HDAC4 levels in SW1353 cells. GSK-3ß rescued IL-1ß-induced downregulation of HDAC4 in SW1353 cells. CONCLUSION: HDAC4 exerted an inhibitory effect on IL-1ß-induced extracellular matrix degradation and was regulated partially by the WNT3A/ß-catenin signaling pathway.