Journal of Neuroscience, Vol 9, 4303-4317, Copyright © 1989 by Society for Neuroscience
Identification of proteins that are developmentally regulated during early cerebral corticogenesis in the rat
DH Geschwind and S Hockfield
Section of Neuroanatomy, Yale University School of Medicine, New Haven, Connecticut 06510.
Between embryonic day 14 (E14) and embryonic day 21 (E21), the rat
neopallium develops from a relatively homogeneous band of mitotic precursor
cells into a complex laminated structure containing diverse classes of
neurons. In order to identify some of the molecular components underlying
this process, 2-dimensional PAGE was used to compare proteins expressed
before cortical neurons are born (E14) with those expressed during
neurogenesis and neuronal migration (E17 and E21). This approach has
permitted the identification of 15 proteins that show greater than 3-fold
changes in their rate of accumulation between E14 and E21. Six proteins
show consistent up-regulation, ranging from 3.2- to 10.7-fold. Five
proteins show consistent down- regulation ranging from 9- to 22-fold. Four
proteins that appear at E21 are not detectable on fluorograms of E14
cortex, even after long exposures, and thus are up-regulated more than
200-fold from E14 to E21 and may be considered to appear de novo. The
molecular weights and isoelectric points of most of these 15 suggest that
they are previously unreported, developmentally regulated proteins.
Comparisons of gels of cortex to gels of lung and heart suggest that
several of these proteins are enriched in brain relative to non-neural
tissues. This analysis also indicates that, despite the large morphogenic
changes observed during this developmental period, few proteins (less than
3%) among the total spectrum analyzed show large changes in their rates of
synthesis.