Spatiotemporally different origins of NG2 progenitors produce cortical interneurons versus glia in the mammalian forebrain.

The studies on the exact lineage composition of NG2 expressing progenitors in the forebrain have been controversial. A number of studies have revealed the heterogeneous nature of postnatal NG2 cells. However, NG2 cells found in embryonic dates are far less understood. Our study indicates that early NG2 progenitors from a ventral origin (i.e., before embryonic day 16.5) tangentially migrate out of the medial ganglionic eminence and give rise to interneurons in deep layers of the dorsal cerebral cortex. The majority of myelinating oligodendrocytes found in both cortical gray and white matters are, in contrast, derived from NG2 progenitors with a neonatal subventricular zone origin. Our lineage tracing data reflect the heterogeneous nature of NG2 progenitor populations and define the relationship between lineage divergence and spatiotemporal origins. Beyond the typical lineage tracing studies of NG2(+) cells, by costaining with lineage-specific markers, our study addresses the origins of heterogeneity and its implications in the differentiation potentials of NG2(+) progenitors.

Solution NMR structure of the 30S ribosomal protein S28E from Pyrococcus horikoshii.

We report NMR assignments and solution structure of the 71-residue 30S ribosomal protein S28E from the archaean Pyrococcus horikoshii, target JR19 of the Northeast Structural Genomics Consortium. The structure, determined rapidly with the aid of automated backbone resonance assignment (AutoAssign) and automated structure determination (AutoStructure) software, is characterized by a four-stranded beta-sheet with a classic Greek-key topology and an oligonucleotide/oligosaccharide beta-barrel (OB) fold. The electrostatic surface of S28E exhibits positive and negative patches on opposite sides, the former constituting a putative binding site for RNA. The 13 C-terminal residues of the protein contain a consensus sequence motif constituting the signature of the S28E protein family. Surprisingly, this C-terminal segment is unstructured in solution.