ABSTRACT
G protein-coupled receptor (GPCR) activation-mediated PKA and PKC pathways have been recognized to be important in ovarian physiology. Expression of regulator of G-protein signaling 2 (RGS2) has been reported in ovarian granulosa cells. The detailed mechanisms in PKA- and PKC-regulated RGS2 expression and cellular translocation in granulosa cells remain mostly unclear. PKA activator 8-bromo-cAMP and PKC activator phorbol-12, 13-didecanoate appeared to rapidly elevate both protein and mRNA levels and promoter activation of RGS2 gene. Two consensus Sp1 elements within the shortest 78 bp fragment of RGS2 promoter sequence were essential for the full responsiveness to PKA and PKC. PKC activation appeared to increase the RGS2 translocation from nucleus to cytosol. PKA- and PKC-mediated RGS2 transcription in a Sp-1-dependent manner and a PKC-mediated RGS2 intracellular translocation were noted in granulosa cells.
Subject(s)
Cyclic AMP-Dependent Protein Kinases/metabolism , Granulosa Cells/metabolism , Protein Kinase C/metabolism , RGS Proteins/genetics , Signal Transduction , Transcriptional Activation , Animals , Cell Line , Female , Gene Expression Regulation , Mice , Promoter Regions, Genetic , Protein Transport , RGS Proteins/analysis , RGS Proteins/metabolismABSTRACT
In this paper we study the characteristics of subwavelength imaging of a photonic crystal (PhC) superlens under the influence of source displacement. For square and triangular lattice photonic crystal lenses, we investigate the influence of changing the lateral position of a single point source on imaging uniformity and stability. We also study the effect of changing the geometrical center of a pair of sources on the resolution of the double image. Both properties are found to be sensitive to the displacement, which implies that a PhC slab cannot be treated seriously as a flat lens. We also show that by introducing material absorption into the dielectric cylinders of the PhC slab and widening the lateral width of the slab, the imaging uniformity and stability can be substantially improved. This study helps us to clarify the underlying mechanisms of some recently found phenomena concerning imaging instability.
