Osterix (Osx), a transcriptional factor essential for osteogenesis, is also critical for in vivo cellular cementum formation. However, the molecular mechanism by which Osx regulates cementoblasts is largely unknown. In this study, we initially demonstrated that overexpression of Osx in a cementoblast cell line upregulated the expression of markers vital to cementogenesis such as osteopontin (OPN), osteocalcin (OCN), and bone sialoprotein (BSP) at both mRNA and protein levels, and enhanced alkaline phosphatase (ALP) activity. Unexpectedly, we demonstrated a sharp increase in the expression of DKK1 (a potent canonical Wnt antagonist), and a great reduction in protein levels of β-catenin and its nuclear translocation by overexpression of Osx. Further, transient transfection of Osx reduced protein levels of TCF1 (a target transcription factor of β-catenin), which were partially reversed by an addition of DKK1. We also demonstrated that activation of canonical Wnt signaling by LiCl or Wnt3a significantly enhanced levels of TCF1 and suppressed the expression of OPN, OCN, and BSP, as well as ALP activity and formation of extracellular mineralized nodules. Importantly, we confirmed that there were a sharp reduction in DKK1 and a concurrent increase in β-catenin in Osx cKO mice (crossing between the Osx loxP and 2.3 Col 1-Cre lines), in agreement with the in vitro data. Thus, we conclude that the key role of Osx in control of cementoblast proliferation and differentiation is to maintain a low level of Wnt-β-catenin via direct up-regulation of DKK1.

Diabetic cardiomyopathy is associated with suppressed autophagy and augmented inflammation in the heart. The effects of Tax1 binding protein 1 (TAX1BP1) on both autophagy and inflammation suggest that it may participate in the progression of diabetic cardiomyopathy. Mice were injected with streptozotocin (STZ) to induce experimental diabetes. An adenovirus system was used to induce heart specific TAX1BP1 overexpression 12 weeks after STZ injection. TAX1BP1 expression was significantly decreased in STZ-induced diabetic mouse hearts. TAX1BP1 overexpression in the heart alleviated cardiac hypertrophy and fibrosis, attenuated inflammation, oxidative stress, and apoptosis, and improved cardiac function in STZ-induced diabetic mice. Diabetic mice exhibited decreased autophagy. By contrast, increased autophagy was observed in diabetic mice overexpressing TAX1BP1. TAX1BP1 overexpression promoted autophagic flux, as demonstrated by increased LC3-RFP fluorescence in vitro. Furthermore, the autophagy inhibitor 3-MA abolished the protective effects of TAX1BP1 in vivo. Interestingly, we found that TAX1BP1 increased autophagy via the activation of a non-canonical NF-κB signaling pathway. Conversely, RelB knockdown disrupted the protective effects of TAX1BP1 in cardiomyocytes. TAX1BP1 thus restores the decreased autophagy level, leading to decreased inflammatory responses and oxidative stress and reduced apoptosis in cardiomyocytes.

Periodontitis is a prevalent and chronic inflammatory disease that is interrelated with systemic health. Periodontitis can be promoted by tumor necrosis factor α (TNF-α). Cementum, a vital part of the periodontium, is a bone-like mineralized tissue that is produced by cementoblasts. Our laboratory previously revealed that TNF-α inhibits cementoblast differentiation and mineralization. However, how TNF-α modulates cementoblast differentiation and mineralization remains largely unknown. MicroRNA-155 (miR-155) is induced and regulates TNF-α-inhibited osteogenic differentiation. In this study, we found that miR-155-3p was increased during TNF-α-stimulated OCCM-30 cells and involved in cementoblast differentiation and mineralization. Overexpression of miR-155-3p suppressed cementoblast mineralization. Bioinformatics analysis revealed that potassium channel tetramerization domain containing 1 ( Kctd1) is a candidate target gene of miR-155-3p. Moreover, miR-155-3p overexpression suppressed KCTD1 levels. Meanwhile, its knockdown increased KCTD1 expression. Transfection with miR-155-3p also inhibited the luciferase activity of 3'-untranslated regions in the Kctd1 wild type but not the mutant. These data indicated that Kctd1 is a direct and novel target of miR-155-3p. The Wnt signaling pathway inhibits cementoblast differentiation, and we further demonstrated that miR-155-3p partially modulates cementoblast differentiation through the canonical Wnt signaling pathway. In addition to the gain/loss function assay of miR-155-3p, the luciferase activity assay of canonical Wnt signaling was performed. The assays revealed that miR-155-3p increased β-catenin-mediated transcriptional activation. Overall, our data clarified that miR-155-3p mediated TNF-α-inhibited cementoblast differentiation by targeting Kctd1, at least partially through canonical Wnt signaling pathway. These findings reveal the expanded function of miRNAs in cementoblast differentiation and mineralization.

OX40, which belongs to the tumour necrosis factor (TNF)-receptor family, is a costimulatory receptor that can potentiate T-cell receptor signalling on the surface of T-lymphocytes. The role of OX40 in non-immune systems, particularly the cardiovascular system, has not been defined. In the present study, we observed a noticeable increase in OX40 expression during cardiac remodelling in rodent heart. In the present study, cardiac hypertrophy was induced by aortic banding (AB) in OX40 knockout (KO) mice and wild-type (WT) mice. After 8 weeks, the OX40 KO mice showed significantly attenuated cardiac hypertrophy, fibrosis and inflammation as well as preserved cardiac function compared with the WT mice. Follow-up in vitro studies suggested that CD4 T-lymphocyte proliferation and pro-inflammatory cytokine release were significantly decreased, whereas anti-inflammatory cytokine release was considerably increased in OX40 KO mice compared with WT mice as assessed by Cell Counting Kit-8 (CCK-8) assay and ELISA. Co-culturing neonatal rat cardiomyocytes with the activated supernatant of CD4 T-lymphocytes from OX40 KO mice reduced the hypertrophy response. Interestingly, OX40 KO mice with reconstituted CD4 T-lymphocytes presented deteriorated cardiac remodelling. Collectively, our data indicate that OX40 regulates cardiac remodelling via the modulation of CD4 T-lymphocytes.