Wound healing is a complex process and has been the subject of intense research for a long time. The recent emergence of nanotechnology has provided a new therapeutic modality in silver nanoparticles for use in burn wounds. Nonetheless, the beneficial effects of silver nanoparticles on wound healing remain unknown. We investigated the wound-healing properties of silver nanoparticles in an animal model and found that rapid healing and improved cosmetic appearance occur in a dose-dependent manner. Furthermore, through quantitative PCR, immunohistochemistry, and proteomic studies, we showed that silver nanoparticles exert positive effects through their antimicrobial properties, reduction in wound inflammation, and modulation of fibrogenic cytokines. These results have given insight into the actions of silver and have provided a novel therapeutic direction for wound treatment in clinical practice.

Generation of superoxide by professional phagocytes is an important mechanism of host defense against bacterial infection. Several protein kinase C (PKC) isoforms have been found to phosphorylate p47phox, resulting in its membrane translocation and activation of the NADPH oxidase. However, the mechanism by which specific PKC isoforms regulate NADPH oxidase activation remains to be elucidated. In this study, we report that PKCδ phosphorylation in its activation loop is rapidly induced by fMLF and is essential for its ability to catalyze p47phox phosphorylation. Using transfected COS-7 cells expressing gp91phox, p22phox, p67phox, and p47phox (COS-phox cells), we found that a functionally active PKCδ is required for p47phox phosphorylation and reconstitution of NADPH oxidase. PKCβII cannot replace PKCδ for this function. Characterization of PKCδ/PKCβII chimeras has led to the identification of the catalytic domain of PKCδ as a target of regulation by fMLF, which induces a biphasic (30 and 180 s) phosphorylation of Thr505 in the activation loop of mouse PKCδ. Mutation of Thr505 to alanine abolishes the ability of PKCδ to catalyze p47phox phosphorylation in vitro and to reconstitute NADPH oxidase in the transfected COS-phox cells. A correlation between fMLF-induced activation loop phosphorylation and superoxide production is also established in the differentiated PLB-985 human myelomonoblastic cells. We conclude that agonist-induced PKCδ phosphorylation is a novel mechanism for NADPH oxidase activation. The ability to induce PKCδ phosphorylation may distinguish a full agonist from a partial agonist for superoxide production.

BackgroundThe chemopreventive effects of resveratrol (RSV) on prostate cancer have been well established; the androgen receptor (AR) plays pivotal roles in prostatic tumorigenesis. However, the exact underlying molecular mechanisms about the effects of RSV on AR have not been fully elucidated. A model system is needed to determine whether and how RSV represses AR transcriptional activity.MethodologyThe AR cDNA was first cloned into the retroviral vector pOZ-N and then integrated into the genome of AR-negative HeLa cells to generate the AR(+) cells. The constitutively expressed AR was characterized by monitoring hormone-stimulated nuclear translocation, DNA binding, and transcriptional activation, with the AR(-) cells serving as controls. AR(+) cells were treated with RSV, and both AR protein levels and AR transcriptional activity were measured simultaneously. Chromatin immunoprecipitation (ChIP) assays were used to detect the effects of RSV on the recruitment of AR to its cognate element (ARE).ResultsAR in the AR (+) stable cell line functions in a manner similar to that of endogenously expressed AR. Using this model system we clearly demonstrated that RSV represses AR transcriptional activity independently of any effects on AR protein levels. However, neither the hormone-mediated nucleus translocation nor the AR/ARE interaction was affected by RSV treatment.ConclusionWe demonstrated unambiguously that RSV regulates AR target gene expression, at least in part, by repressing AR transcriptional activity. Repressive effects of RSV on AR activity result from mechanisms other than the affects of AR nuclear translocation or DNA binding.