Veronica A. Alvarez, Dennis A. Ridenour, and Bernardo L. Sabatini

Even for scientists it often takes a while to appreciate that the latest and greatest new technique has its limitations. In this week's Journal, Alvarez et al. provide an example in the case of gene silencing with short hairpin RNA (shRNA) sequences. In rat organotypic hippocampal slices, the authors expressed an shRNA sequence with homology to luciferase (shLUCI), a gene not present in the mammalian genome. shLUCI expression substantially reduced dendritic branch complexity, spine density, and miniature synaptic currents, consistent with a loss of synaptic number. These effects required the double-stranded RNA-dependent protein kinase that activates interferon target genes. The authors also transfected cells with two forms of shRNA against a chromatin-regulating protein, one known to activate the interferon-like response, the other not. The one with the off-target interferon-like response also reduced dendritic complexity confirming an off-target, and thus nonspecific, action on dendritic and synaptic structures.

2. Making Oligodendrocytes in the SVZ

Bndicte Menn, Jose Manuel Garcia-Verdugo, Cynthia Yaschine, Oscar Gonzalez-Perez, David Rowitch, and Arturo Alvarez-Buylla

Type B precursor cells in the adult subventricular zone (SVZ) express glial fibrillary acidic protein (GFAP) and are known to produce new neurons as well as astrocytes. Oligodendrocyte progenitor cells (OPCs), characterized by NG2 chrondrotin sulfate expression, are rather widely distributed in cortex and can generate mature oligodendrocytes. However, this week, Menn et al. show that type B cells in the SVZ can also produce limited numbers of oligodendrocytes in vivo. The authors used several approaches to identify cells. For example, using electron microscropy, the authors characterized the subset of cells in the SVZ that expre
'"/>

Contact: Sara Harris
sharris@sfn.org
202-962-4000
Society for Neuroscience
25-Jul-2006