Classical tissue recombination studies demonstrated that initiation of tooth development depends on activation of odontogenic potential in the mesenchyme by signals from the presumptive dental epithelium. Although several members of the Wnt family of signaling molecules are expressed in the presumptive dental epithelium at the beginning of tooth initiation, whether Wnt signaling is directly involved in the activation of the odontogenic mesenchyme has not been characterized. In this report, we show that tissue-specific inactivation of β-catenin, a central component of the canonical Wnt signaling pathway, in the developing tooth mesenchyme caused tooth developmental arrest at the bud stage in mice. We show that mesenchymal β-catenin function is required for expression of Lef1 and Fgf3 in the developing tooth mesenchyme and for induction of primary enamel knot in the developing tooth epithelium. Expression of Msx1 and Pax9, two essential tooth mesenchyme transcription factors downstream of Bmp and Fgf signaling, respectively, were not altered in the absence of β-catenin in the tooth mesenchyme. Moreover, we found that constitutive stabilization of β-catenin in the developing palatal mesenchyme induced aberrant palatal epithelial invaginations that resembled early tooth buds both morphologically and in epithelial molecular marker expression, but without activating expression of Msx1 and Pax9 in the mesenchyme. Together, these results indicate that activation of the mesenchymal odontogenic program during early tooth development requires concerted actions of Bmp, Fgf and Wnt signaling from the presumptive dental epithelium to the mesenchyme.

Idiopathic anterior uveitis, Behçet disease, and VKH syndrome are the most common entities of uveitis in China. Ocular toxoplasmosis, ocular histoplasmosis, and birdshot retinochoroidopathy are less common or absent in China.

Cleft palate is one of the most common birth defects in humans. Whereas gene knockout studies in mice have shown that both the Osr2 and Pax9 transcription factors are essential regulators of palatogenesis, little is known about the molecular mechanisms involving these transcription factors in palate development. We report here that Pax9 plays a crucial role in patterning the anterior-posterior axis and outgrowth of the developing palatal shelves. We found that tissue-specific deletion of Pax9 in the palatal mesenchyme affected Shh expression in palatal epithelial cells, indicating that Pax9 plays a crucial role in the mesenchyme-epithelium interactions during palate development. We found that expression of the Bmp4, Fgf10, Msx1 and Osr2 genes is significantly downregulated in the developing palatal mesenchyme in Pax9 mutant embryos. Remarkably, restoration of Osr2 expression in the early palatal mesenchyme through a Pax9Osr2KI allele rescued posterior palate morphogenesis in the absence of Pax9 protein function. Our data indicate that Pax9 regulates a molecular network involving the Bmp4, Fgf10, Shh and Osr2 pathways to control palatal shelf patterning and morphogenesis.

Previous studies have suggested that Bmp4 is a key Msx1-dependent mesenchymal odontogenic signal for driving tooth morphogenesis through the bud-to-cap transition. Whereas all tooth germs were arrested at the bud stage in Msx1–/– mice, we show that depleting functional Bmp4 mRNAs in the tooth mesenchyme, through neural crest-specific gene inactivation in Bmp4f/f;Wnt1Cre mice, caused mandibular molar developmental arrest at the bud stage but allowed maxillary molars and incisors to develop to mineralized teeth. We found that expression of Osr2, which encodes a zinc finger protein that antagonizes Msx1-mediated activation of odontogenic mesenchyme, was significantly upregulated in the molar tooth mesenchyme in Bmp4f/f;Wnt1Cre embryos. Msx1 heterozygosity enhanced maxillary molar developmental defects whereas Osr2 heterozygosity partially rescued mandibular first molar morphogenesis in Bmp4f/f;Wnt1Cre mice. Moreover, in contrast to complete lack of supernumerary tooth initiation in Msx1–/–Osr2–/– mice, Osr2–/–Bmp4f/f;Wnt1Cre compound mutant mice exhibited formation and subsequent arrest of supernumerary tooth germs that correlated with downregulation of Msx1 expression in the tooth mesenchyme. In addition, we found that the Wnt inhibitors Dkk2 and Wif1 were much more abundantly expressed in the mandibular than maxillary molar mesenchyme in wild-type embryos and that Dkk2 expression was significantly upregulated in the molar mesenchyme in Bmp4f/f;Wnt1Cre embryos, which correlated with the dramatic differences in maxillary and mandibular molar phenotypes in Bmp4f/f;Wnt1Cre mice. Together, these data indicate that Bmp4 signaling suppresses tooth developmental inhibitors in the tooth mesenchyme, including Dkk2 and Osr2, and synergizes with Msx1 to activate mesenchymal odontogenic potential for tooth morphogenesis and sequential tooth formation.

Two independent clinical studies have reported that fenofibrate, a peroxisome proliferator-activated receptor α (PPARα) agonist, has robust therapeutic effects on microvascular complications of diabetes, including diabetic retinopathy (DR) in type 2 diabetic patients. However, the expression and function of PPARα in the retina are unclear. Here, we demonstrated that PPARα is expressed in multiple cell types in the retina. In both type 1 and type 2 diabetes models, expression of PPARα, but not PPARβ/δ or PPARγ, was significantly down-regulated in the retina. Furthermore, high-glucose medium was sufficient to down-regulate PPARα expression in cultured retinal cells. To further investigate the role of PPARα in DR, diabetes was induced in PPARα knockout (KO) mice and wild-type (WT) mice. Diabetic PPARα KO mice developed more severe DR, as shown by retinal vascular leakage, leukostasis, pericyte loss, capillary degeneration, and over-expression of inflammatory factors, compared with diabetic WT mice. In addition, overexpression of PPARα in the retina of diabetic rats significantly alleviated diabetes-induced retinal vascular leakage and retinal inflammation. Furthermore, PPARα overexpression inhibited endothelial cell migration and proliferation. These findings revealed that diabetes-induced down-regulation of PPARα plays an important role in DR. Up-regulation or activation of PPARα may represent a novel therapeutic strategy for DR.

No abstract

To investigate the relationship between circulating microRNA 223 (miR-223) levels and clopidogrel responsiveness in patients with coronary heart disease. A total of 62 consecutive patients with troponin-negative non-ST elevation acute coronary syndrome (NSTE-ACS) scheduled for elective percutaneous coronary intervention were enrolled. The plasma circulating miR-223 levels were quantified by real-time PCR, and platelet reactivity was determined by platelet reactivity index (PRI), measured by vasodilator-stimulated phosphoprotein (VASP) phosphorylation flow cytometry after 300 mg (for at least 24 h) or 75 mg clopidogel (for at least 5 days) plus aspirin treatment. All subjects were dichotomized according to PRI median (normal-responders: PRI ≤ 56.3%, n = 31 and low-responders: PRI > 56.3%, n = 31). Compared with normal-responders, circulating miR-223 level was significantly decreased in low-responders (P = 0.007). In addition, miR-223 level was statistically correlated with PRI (Spearman r = -0.379, P = 0.002). Stepwise binary logistic regression analysis revealed that among factors that potentially influence platelet reactivity (CYP2C19*2/*3 loss-of-function genotypes, use of calcium channel blockers/proton-pump inhibitors, age, diabetes and smoking), decreased circulating miR-223 level was the only independent predictor for the presence of PRI-determined lower responders (OR 0.111, 95% CI 0.018-0.692, P = 0.019). Our data suggest that circulating miR-223 may serve as a novel biomarker for assessment of clopidogrel responsiveness in troponin-negative NSTE-ACS patients.

P38MAPK mediates cytokine induced inflammation in nucleus pulposus (NP) cells and involves in multiple cellular processes which are related to intervertebral disc degeneration (IDD). The aim of this study was to investigate the expression, activation and function of p38 MAPK isoforms (α,β, γ and δ) in degenerative NP and the effect of p38 activation in NP cells on macrophage polarization. P38 α, β and δ isoforms are preferential expressed, whereas the p38γ isoform is absent in human NP tissue. LV-sh-p38α, sh-p38β transfection in NP cells significantly decreased the ADAMTS-4,-5, MMP-13,CCL3 expression and restored collagen-II and aggrecan expression upon IL-1β stimulation. As compared with p38α and p38β, p38δ exhibited an opposite effect on ADAMTS-4,-5, MMP-13 and aggrecan expression in NP cells. Furthermore, the production of GM-CSF and IFNγ which were trigged by p38α or p38β in NP cells induced macrophage polarization into M1 phenotype. Our finding indicates that p38 MAPK α, β and δ isoform are predominantly expressed and activated in IDD. P38 positive NP cells modulate macrophage polarization through the production of GM-CSF and IFNγ. Hence, Our study suggests that selectively targeting p38 isoforms could ameliorate the inflammation in IDD and regard IDD progression.