Jp. Hornung et Bm. Riederer, Medium-sized neurofilament protein related to maturation of a subset of cortical neurons, J COMP NEUR, 414(3), 1999, pp. 348-360
Neurofilaments are typical structures of the neuronal cytoskeleton and part
icipate in the formation and stabilization of the axonal and dendritic arch
itecture. In this study, we have characterized a murine monoclonal antibody
, FNP7, that is directed against the medium-sized neurofilament subunit NF-
M. This antibody identifies a subset of neurons in the cerebral cortex of v
arious species including human and in organotypic cultures of rat cortex. I
n the neocortex of all species examined, the antibody labels pyramidal cell
s in layers III, V, and VI, with a distinctive laminar distribution between
architectonic boundaries. In comparison with other antibodies directed aga
inst NF-M, the FNP7 antibody identifies on blots two forms of NF-M that app
ear relatively late during development, at the time when dynamic growth of
processes changes to the stabilization of the formed processes. Dephosphory
lation with alkaline phosphatase unmasks the site, making it detectable for
the FNP7 antibody. The late appearance suggests that the site is present d
uring early development in phosphorylated form and with increasing maturati
on becomes dephosphorylated, mainly in dendrites. This event may relate to
changes in cytoskeleton stability in a late phase of dendritic maturation.
Furthermore, mainly corticofugal projections and only few callosal axons ar
e stained, suggesting a differential phosphorylation in a subset of axons.
The antibody provides a useful marker to study subsets of pyramidal cells i
n vivo, in vitro, and under experimental conditions. (C) 1999 Wiley-Liss, I
nc.