JARID1B represses the osteogenic potential of human periodontal ligament mesenchymal cells.

BACKGROUND: Here, we evaluated whether the histone lysine demethylase 5B (JARID1B), is involved in osteogenic phenotype commitment of periodontal ligament cells (PDLCs), by considering their heterogeneity for osteoblast differentiation. MATERIALS AND METHODS: Epigenetic, transcriptional, and protein levels of a gene set, involved in the osteogenesis, were investigated by performing genome-wide DNA (hydroxy)methylation, mRNA expression, and western blotting analysis at basal (without osteogenic induction), and at the 3rd and 10th days of osteogenic stimulus, in vitro, using PDLCs with low (l) and high (h) osteogenic potential as biological models. RESULTS: h-PDLCs showed reduced levels of JARID1B, compared to l-PDLCs, with significant inversely proportional correlations between RUNX2 and RUNX2/p57. Epigenetically, a significant reduction in the global H3K4me3 content was observed only in h-PDLCs. Immunoblotting data reveal a significant reduction in the global H3K4me3 content, at 3 days of induction only in h-PDLCs, while an increase in the global H3K4me3 content was observed at 10 days for both PDLCs. Additionally, positive correlations were found between global H3K4me3 levels and JARID1B gene expression. CONCLUSIONS: Altogether, our results show the crucial role of JARID1B in repressing PDLCs osteogenic phenotype and this claims to pre-clinical protocols proposing JARID1B as a potential therapeutic target.

Non-coding RNAs repressive role in post-transcriptional processing of RUNX2 during the acquisition of the osteogenic phenotype of periodontal ligament mesenchymal stem cells.

Mesenchymal stem cells are candidates for therapeutic strategies in periodontal repair due to their osteogenic potential. In this study, we identified epigenetic markers during osteogenic differentiation, taking advantage of the individual pattern of mesenchymal cells of the periodontal ligament with high (h-PDLCs) and low (l-PDLCs) osteogenic capacity. We found that the involvement of non-coding RNAs in the regulation of the RUNX2 gene is strongly associated with high osteogenic potential. Moreover, we evaluated miRs and genes that encode enzymes to process miRs and their biogenesis. Our data show the high expression of the XPO5 gene, and miRs 7 and 22 observed in the l-PDLCs might be involved in acquiring osteogenic potential, suppressing RUNX2 gene expression. Further, an inversely proportional correlation between lncRNAs (HOTAIR and HOTTIP) and RUNX2 gene expression was observed in both l- and h-PDLCs, and it was also related to the distinct osteogenic phenotypes. Thus, our results indicate the low expression of XPO5 in h-PDLC might be the limiting point for blocking the miRs biogenesis, allowing the high gene expression of RUNX2. In accordance, the low expression of miRs, HOTAIR, and HOTTIP could be a prerequisite for increased osteogenic potential in h-PDLCs. These results will help us to better understand the underlying mechanisms of osteogenesis, considering the heterogeneity in the osteogenic potential of PDLCs that might be related to a distinct transcriptional profile of lncRNAs and the biogenesis machinery.

Laminar shear stress-provoked cytoskeletal changes are mediated by epigenetic reprogramming of TIMP1 in human primary smooth muscle cells.

Whereas endothelial responses to shear stress are well-characterized, the cell physiological effects of shear stress in smooth muscle cells (SMCs) remain largely obscure. As SMCs are directly challenged by shear stress after endothelial denuding injury following procedures such as angioplasty or endarterectomy, characterization of these responses represents an important scientific question. Hence we decided to contrast cytoskeletal reorganization, epigenetic reprogramming, signaling transduction, and changes in miRNA (miRs) profiles in primary human aortic smooth muscle cells (AoSMCs) between unstressed cells and cells exposed to shear stress. We observed that shear stress-provoked reorganization of the actin cytoskeleton in an apparently Cofilin-dependent fashion and which related to altered integrin signaling, apparently caused by remodeling of the extracellular matrix. The latter appeared a downstream effect of increased expression of matrix metalloproteinases and downregulation of tissue metalloproteinase inhibitor 1 (TIMP1) protein levels. In turn, these effects related to shear stress-provoked changes in expression and nuclear localization of the epigenetic regulators demethylases TET1, TET2, DNMT1, DNMT3A and DNMT3B, HDAC6, and SIRT1. Accordingly, TIMP1 promotor CpG hypomethylation was a prominent effect, and resulted in a significant increase in TIMP1 transcription, which may also have related increased expression of miRs involved in modulating TIMP1 translation. Thus epigenetic-reprogramming of TIMP1 emerges as critical element in smooth muscle responses to mechanical signals and as epigenetic machinery is amendable to pharmacological manipulation, this pathway may have important clinical consequences.

Genome-wide DNA (hydroxy) methylation reveals the individual epigenetic landscape importance on osteogenic phenotype acquisition in periodontal ligament cells.

BACKGROUND: Mesenchymal cells' biology has been an important investigative tool to maximize bone regeneration through tissue engineering. Here we used mesenchymal cells from periodontal ligament (PDLCs) with high (h-) and low (l-) osteogenic potential, isolated from different donors, to investigate the impact of the individual epigenetic and transcriptional profiles on the osteogenic potential. METHODS: Genome-wide and gene-specific DNA (hydroxy) methylation, mRNA expression and immunofluorescence analysis were carried out in h- and l-PDLCs at DMEM (non-induced to osteogenesis) and OM (induced-3rd and 10th days of osteogenic differentiation) groups in vitro. RESULTS: Genome-wide results showed distinct epigenetic profile among PDLCs with most of the differences on 10th day of OM; DMEMs showed higher concentrations (xOM) of differentially methylated probes in gene body, intronic and open sea (3rd day), increasing this concentration in TSS200 and island regions, at 10 days. At basal levels, h- and l-PDLCs showed different transcriptional profiles; l-PDLCs demonstrated higher levels of NANOG/OCT4/SOX2, BAPX1, DNMT3A, TET1/3, and lower levels of RUNX2 transcripts, confirmed by NANOG/OCT4 and RUNX2 immunofluorescence. After osteogenic induction, the distinct transcriptional profile of multipotentiality genes was maintained among PDLCs. In l-PDLCs, the anti-correlation between DNA methylation and gene expression in RUNX2 and NANOG indicates methylation could play a role in modulating both transcripts. CONCLUSIONS: Epigenetic and transcriptional distinct profiles detected at basal levels among PDLCs were maintained after osteogenic induction. We cannot discard the existence of a complex that represses osteogenesis, suggesting the individual donors' characteristics have significant impact on the osteogenic phenotype acquisition.