Identification of differentially expressed proteins in murine embryonic and postnatal cortical neural progenitors.
BACKGROUND
The central nervous system (CNS) develops from a heterogeneous pool of neural stem and progenitor cells (NSPC), the underlying differences among which are poorly understood. The study of NSPC would be greatly facilitated by the identification of additional proteins that mediate their function and that would distinguish amongst different progenitor populations.


RESULTS
To identify membrane and membrane-associated proteins expressed by NSPC, we used a proteomics approach to profile NSPC cultured as neurospheres (NS) isolated from the murine cortex during a period of neurogenesis (embryonic day 11.5, E11.5), as compared to NSPC isolated at a peak of gliogenesis (postnatal day 1, P0) and to differentiated E11.5 NS. 54 proteins were identified with high expression in E11.5 NS, including the TrkC receptor, several heterotrimeric G proteins, and the Neogenin receptor. 24 proteins were identified with similar expression in E11.5 and P0 NS over differentiated E11.5 NS, and 13 proteins were identified with high expression specifically in P0 NS compared to E11.5 NS. To illustrate the potential relevance of these identified proteins to neural stem cell biology, the function of Neogenin was further studied. Using Fluorescence Activated Cell Sorting (FACS) analysis, expression of Neogenin was associated with a self-renewing population present in both E11.5 and adult subventricular zone (SVZ) NS but not in P0 NS. E11.5 NS expressed a putative Neogenin ligand, RGMa, and underwent apoptosis when exposed to a ligand-blocking antibody.


CONCLUSIONS
There are fundamental differences between the continuously self-renewing and more limited progenitors of the developing cortex. We identified a subset of differentially expressed proteins that serve not only as a set of functionally important proteins, but as a useful set of markers for the subsequent analysis of NSPC. Neogenin is associated with the continuously self-renewing and neurogenic cells present in E11.5 cortical and adult SVZ NS, and the Neogenin/RGMa receptor/ligand pair may regulate cell survival during development.
Shoemaker
Lorelei D
LD
Pasarow Mass Spectrometry Laboratory, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, California, United States of America.
Orozco
Nicholas M
NM
Geschwind
Daniel H
DH
Whitelegge
Julian P
JP
Faull
Kym F
KF
Kornblum
Harley I
HI
D000818:Animals; D015153:Blotting, Western; D049109:Cell Proliferation; D002478:Cells, Cultured; D002540:Cerebral Cortex / Q000166:cytology / Q000196:embryology / Q000378:metabolism; D015180:Electrophoresis, Gel, Two-Dimensional; D020869:Gene Expression Profiling; D018507:Gene Expression Regulation, Developmental; D013058:Mass Spectrometry; D008565:Membrane Proteins / Q000032:analysis* / Q000235:genetics / Q000378:metabolism; D051379:Mice; D009474:Neurons / Q000166:cytology / Q000378:metabolism*; D040901:Proteomics / Q000379:methods*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013234:Stem Cells / Q000166:cytology / Q000378:metabolism*; D013997:Time Factors
D008565:Membrane Proteins; C091279:neogenin