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Obesity has become a major public health problem of global significance. Today, aspirin remains the most commonly used medication for the treatment of pyrexia, pain, inflammation and antiplatelet. The present study aims at evaluating the possible existence of a putative p53-dependent pathway underlying the aspirin-induced inhibition of adipogenesis. Cell migration assay was identified by the ability to migrate through Transwell insert. Oil Red O staining was employed to quantify adipose accumulation. The concentration of glucose and triglyceride were measured by using assay kits. The expression levels of several master regulatory molecules controlling various signal pathways were monitored using the immunoblotting techniques. Aspirin significantly inhibited preadipocyte migration and adipose accumulation. The p53-p21 signaling and the expression of differentiation marker glycerol-3-phosphate dehydrogenase were increased in a dose-dependent manner. It indicated that aspirin induced adipocyte differentiation through p53-p21 pathway. The oncogenic ERK 1/2 MAPK signaling was induced, whereas, the expression of adipogenic markers peroxisome proliferator-activated receptor γ (PPARγ), adipocyte fatty acid-binding protein (A-FABP) and inflammatory factors cyclooxygenase-2 (Cox-2), tumor necrosis factor α (TNFα) and inducible nitric oxide synthase (iNOS) were inhibited. Aspirin negatively regulated the pentose phosphate pathway (PPP) by inhibiting the expression of rate-limiting enzyme glucose-6-phosphate dehydrogenase. Knockdown the expression of oncogenic ERK 1/2 MAPK by using 10 μM PD98059 significantly increased triglyceride synthesis, adipose accumulation and activated PPP, however, decreased glucose uptake. Diverted the glucose flux to PPP, rather than increased glucose uptake, was associated with adipogenesis. Down-regulated the expression of tumor suppressor p53 by 10 μM pifithrin-α (PFTα) alone had no effect on adipose accumulation. However, administration of aspirin accompanied with PFTα abolished aspirin-induced inhibition of adipogenesis. We demonstrated that aspirin-induced inhibition of adipogenesis was p53-dependent and associated with inactivation of PPP. Blockade PPP may be a novel strategy for obesity prevention and therapy. Moreover, when use aspirin in therapeutic strategy, the p53 status should be considered. [ABSTRACT FROM AUTHOR]

β-Tricalcium phosphate (β-TCP) is an osteoconductive material in clinical. In this study, we have doped silica (Si) into β-TCP and enhanced its bioactive and osteostimulative properties. To check its effectiveness, a series of Si-doped with different ratios were prepared to make new bioactive and biodegradable biocomposites for bone repair. Formation of the diametral tensile strength, ions released and weight loss of cements was considered after immersion. In addition, we also examined the behavior of human dental pulp cells (hDPCs) cultured on Si-doped β-TCP cements. The results showed that setting time and injectability of the Si-doped β-TCP cements were decreased as the Si content was increased. At the end of the immersion point, weight losses of 30.1%, 36.9%, 48.1%, and 55.3% were observed for the cement doping 0%, 10%, 20%, and 30% Si into β-TCP cements, respectively. In vitro cell experiments show that the Si-rich cements promote human dental pulp cell (hDPC) proliferation and differentiation. However, when the Si-doped in the cement is more than 20%, the amount of cells and osteogenesis protein of hDPCs was stimulated by Si released from Si-doped β-TCP cements. The degradation of β-TCP and osteogenesis of Si gives a strong reason to believe that these Si-doped β-TCP cements may prove to be promising bone repair materials. [ABSTRACT FROM AUTHOR]

Myogenic regulatory factor Myf5 plays important roles in muscle development. In zebrafish myf5, a microRNA (miR), termed miR-3906 or miR-In300, was reported to silence dickkopf- 3-related gene (dkk3r or dkk3a), resulting in repression of myf5 promoter activity. However, the membrane receptor that interacts with ligand Dkk3a to control myf5 expression through signal transduction remains unknown. To address this question, we applied immunoprecipitation and LC-MS/MS to screen putative membrane receptors of Dkk3a, and Integrin α6b (Itgα6b) was finally identified. To further confirm this, we used cell surface binding assays, which showed that Dkk3a and Itgα6b were co-expressed at the cell membrane of HEK-293T cells. Cross-linking immunoprecipitation data also showed high affinity of Itgα6b for Dkk3a. We further proved that the β-propeller repeat domains of Itgα6b are key segments bound by Dkk3a. Moreover, when dkk3a and Itgα6b mRNAs were co-injected into embryos, luciferase activity was up-regulated 4-fold greater than that of control embryos. In contrast, the luciferase activities of dkk3a knockdown embryos co-injected with Itgα6b mRNA and Itgα6b knockdown embryos co-injected with dkk3a mRNA were decreased in a manner similar to that in control embryos, respectively. Knockdown of Itgα6b resulted in abnormal somite shape, fewer somitic cells, weaker or absent myf5 expression, and reduced the protein level of phosphorylated p38a in somites. These defective phenotypes of trunk muscular development were similar to those of dkk3a knockdown embryos. We demonstrated that the secreted ligand Dkk3a binds to the membrane receptor Itgα6b, which increases the protein level of phosphorylated p38a and activates myf5 promoter activity of zebrafish embryos during myogenesis. [ABSTRACT FROM AUTHOR]

Myf5 is a myogenic regulatory factor that functions in myogenesis. An intronic microRNA, miR-In300, located within zebrafish myf5 intron I, has been reported to silence myf5 through the targeting of dickkopf-3-related gene (dkk3r). However, the molecular mechanism underlying the control of myf5 expression by dkk3r is unknown. By injecting dkk3r-specific morpholino-oligonucleotide (dkk3r-MO) to knock down Dkk3r, we found that the phosphorylated p38a protein was reduced. Knockdown of p38a resulted in malformed somites and reduced myf5 transcripts, which photocopied the defects induced by injection of dkk3r-MO. To block the MAPK pathway, phosphorylation of p38 was inhibited by introduction of SB203580, which caused the down-regulation of myf5 expression. The GFP signal was dramatically decreased in somites when we injected p38a-MO into embryos derived from transgenic line Tg(myf5(80K):GFP), in which the GFP was driven by the myf5 promoter. Although these p38a-MO-induced defects were rescued by co-injection with p38a mRNA, they were not rescued with p38a mRNA containing a mutation at the phosphorylation domain. Moreover, overexpression of Smad2 or Smad3a enhanced myf5 expression, but the defects induced by the dominant negative form of either Smad2 or Smad3a equaled those of embryos injected with either dkk3r-MO or p38a-MO. These results support the involvement of Smad2∙Smad3a in p38a mediation. Overexpression of Smad4 enabled the rescue of myf5 defects in the dkk3r-MO-injected embryos, but knockdown of either dkk3r or p38a caused Smad4 protein to lose stability. Therefore, we concluded that Dkk3r regulates p38a phosphorylation to maintain Smad4 stability, in turn enabling the Smad2∙Smad3a∙Smad4 complex to form and activate the myf5 promoter. [ABSTRACT FROM AUTHOR]