MicroRNA-214 promotes myogenic differentiation by facilitating exit from mitosis via down-regulation of proto-oncogene N-ras.

Vertebrate muscle differentiation is coordinated by an intricate network of transcription factors requiring proliferating myogenic precursors to withdraw irreversibly from the cell cycle. Recent studies have implicated a large number of microRNAs exerting another layer of control in many aspects of muscle differentiation. By annealing to short recognition sequences in the 3'-untranslated region, microRNAs attenuate target gene expression through translation repression or mRNA degradation. Here, we show that miR-214 promotes myogenic differentiation in mouse C2C12 myoblasts at a step preceding the induction of p21 and myogenin. Blocking miR-214 function with a 2'-O-methylated double-stranded inhibitor maintained C2C12 cells in the active cell cycle, thereby inhibiting the myogenic differentiation. By global gene expression profiling, we identified the proto-oncogene N-ras as one of miR-214 targets. Furthermore, manipulating the N-Ras level with small interfering RNA or adenovirus-mediated forced expression either augmented or attenuated the effect of miR-214, respectively. Thus, our data uncovered a novel microRNA-mediated mechanism that controls myogenic differentiation.

[Studies on solubility enhancement of curcumin by Polyvinylpyrrolidione K30].

OBJECTIVE: To study solubility enhancement of curcumin by Polyvinylpyrrolidione K30 (PVP K30). METHODS: Solid dispersion systems (SDS) of curcumin in PVP K30 were prepared at various weight ratios by co-evaporation of curcumin and PVP K30 ethanol solution. The differential scanning calorimetry (DSC) and powder X-ray diffractometer method were used to describe the status of curcumin in carriers, the UV spectrometry method for determination of curcumin in mediums was established. RESULTS: The curcumin SDS was successfully prepared, the UV spectrometry method was accurate and reliable, and no interference occurred from carrier. The solubility rate in vitro of curcumin was significantly raised. Compared to curcumin, the solubility of curcumin in SDS increased at least 880 folds. CONCLUSION: PVP K30 improves the solubility of curcumin well.