Therefore, ectopic Sox2 expression can induce amacrine cells in the mouse retina from stage E17 onward, possibly by facilitating cell cycle exit.

Recombinant adeno-associated viral (rAAV) vectors are potentially powerful tools for gene therapy of CNS diseases, but their penetration into brain parenchyma is severely limited by the blood-brain barrier (BBB) and current delivery relies on invasive stereotactic injection. Here we evaluate the local, targeted delivery of rAAV vectors into the brains of mice by noninvasive, reversible, microbubble-facilitated focused ultrasound (FUS), resulting in BBB opening that can be monitored and controlled by magnetic resonance imaging (MRI). Using this method, we found that IV-administered AAV2-GFP (green fluorescence protein) with a low viral vector titer (1×109 vg/g) can successfully penetrate the BBB-opened brain regions to express GFP. We show that MRI monitoring of BBB-opening could serve as an indicator of the scale and distribution of AAV transduction. Transduction peaked at 3 weeks and neurons and astrocytes were affected. This novel, noninvasive delivery approach could significantly broaden the application of AAV-viral-vector-based genes for treatment of CNS diseases.

-opioid receptor (KOR) is detected pre-and postsynaptically, but the subcellular localization, translation, and regulation of kor mRNA in presynaptic compartments of sensory neurons remain elusive. In situ hybridization detected axonal distribution of kor mRNA in primary neurons of dorsal root ganglia (DRG). The MS2-fused GFP tracked kor mRNA transport from DRG neuronal soma to axons, requiring its 5 and 3 UTRs. In Campenot chambers, axonal translation of kor mRNA was demonstrated for DRG neurons, which depended on its 5 UTR and was stimulated by KCl depolarization. KCl depolarization of DRG neurons rendered redistribution of kor mRNA from the postpolysomal fraction to the translationally active polysomal fraction. This study provided evidence for mRNA transport and regulation of presynaptic protein synthesis of nonstructural proteins like KOR in primary sensory neurons and demonstrated a mechanism of KCl depolarizationstimulated axonal mRNA redistribution for localized translational regulation.axonal translation O pioid receptors interact with opioid drugs and endogenous opioid ligands to affect pain sensation, consciousness, and autonomic functions. Three major opioid receptor types, , ␦, and are known (1, 2), each belonging to the super family of G protein-coupled transmembrane receptors (3, 4). Gene knockout studies confirmed the functional roles for opioid receptors in mediating the pharmacological actions of various opioid compounds that are among the most commonly prescribed analgesic agents (5). Furthermore, pharmacological studies revealed that the number of opioid receptors was critical to the manifestation of opioid drugs (6). However, extensive studies of transcriptional regulation of opioid receptor genes (7,8) failed to uncover the mechanisms underlying alteration of receptor number or its protein level in neurons that bear a physiological relevance. Recently, posttranscriptional control for the expression of this gene family has begun to be unraveled, primarily, in studying -opioid receptor (KOR) expression (7, 9, 10).KOR protein is detected both pre-and postsynaptically (11)(12)(13)(14). Like many axonal proteins, presynaptic KOR proteins were thought to be synthesized in the soma and then transported to the axons via the axonal transport mechanism (15, 16). However, using in vitro differentiated neurons (17), we have demonstrated transport of kor mRNA into nerve fibers, suggesting an intriguing possibility that kor mRNA might be transported to the axons of KOR-expressing neurons for local translation and regulation. To this end, the phenomena of mRNA transport/targeting and local protein synthesis in the dendrites of invertebrate and vertebrate neurons have been established, but the source of axonal proteins remained heavily debated (18-21). Evidence for axonal mRNA transport and local protein synthesis was provided primarily for structural proteins, although local synthesis of EphA2 receptor, a protein involved in axonal pathfinding has been demonstrated (22-29). Additionally, it was shown that...

The cellular retinoic acid binding protein I gene is induced by thyroid hormone (T3) through a T3 response element (TRE) approximately 1 kb upstream of the basal promoter. The upstream region is organized into a positioned nucleosomal array with the N1 nucleosome spanning the GC box region. T3 induces apparent interactions between chromatin segments containing the TRE and the GC box regions and the sliding of upstream nucleosomes toward N1 with concomitant N1 remodeling. Concurrently, the chromatin-remodeling factor BRM is replaced by BRG1 and histones are hyperacetylated. All these events are abolished in Med1/Trap220 null cells, indicating a key role for TRAP/Mediator in these processes. A MED1/TRAP220-containing Mediator complex constitutively occupies the GC box region but not the TRE, serving as a nexus for distal and proximal factors. This indicates new TRAP/Mediator functions in facilitating ultimate recruitment and function of RNA polymerase II and the general transcription machinery.