Je. Minturn et al., EARLY POSTMITOTIC NEURONS TRANSIENTLY EXPRESS TOAD-64, A NEURAL-SPECIFIC PROTEIN, Journal of comparative neurology, 355(3), 1995, pp. 369-379
To identify proteins involved in the early development of the mammalia
n cerebral cortex, we previously used two-dimensional gels to compare
proteins synthesized at different stages in corticogenesis in the embr
yonic rat at embryonic day 14 (E14), E17, and E21. During this period,
the cortex develops from a morphologically homogeneous population of
proliferative precursor cells into a complex structure containing a di
verse array of terminally differentiated neurons. Several proteins are
up-regulated coincident with the generation of postmitotic neurons. H
ere we describe the purification, partial amino acid sequencing, and c
haracterization of one of these proteins, TOAD-64 (Turned On After Div
ision; 64 MDa), using polyclonal antisera to two synthetic peptides fr
om the protein. This analysis reveals that TOAD-64 is a 64,000 Da prot
ein that increases in abundance over the period of corticogenesis and
then subsequently decreases to very low levels in the adult. The prote
in is neural specific and is expressed by postmitotic neurons as they
begin their migration out of the ventricular zone into the developing
cortical plate. It is expressed in advance of most other neuronal prot
eins. Progenitor cells do not express TOAD-64. Therefore, this protein
is a marker for postmitotic cells that have made a commitment to a ne
uronal phenotype. The extremely early expression, the relative abundan
ce in newly born neurons, as well as the restriction in expression to
the period of initial neuronal differentiation suggest that TOAD-64 ma
y be a key structural protein for early neuronal function. (C) 1995 Wi
ley-Liss, Inc.