Journal of Neuroscience, Vol 4, 1705-1714, Copyright © 1984 by Society for Neuroscience
The dynamics of nerve growth factor-induced neurofilament and vimentin filament expression and organization in PC12 cells
VM Lee and C Page
Monoclonal antibodies specific for neurofilament (NF) subunits or for
vimentin filament (VF) protein were used to study nerve growth factor
(NGF)-induced intermediate filament expression and organization in a rat
pheochromocytoma cell line (PC12 cells). NGF induced increased amounts of
NF subunits and VF protein, and they were, in part, differentially
localized within PC12 cells. The relative expression of each of the NF
subunits and of the VF protein was measured by an enzyme- linked
immunosorbent assay which revealed that PC12 cells grown in the absence of
NGF (PC12- cells) contained 3 times more VF than 68,000- dalton NF subunits
and only barely detectable amounts of 150,000- and 200,000-dalton NF
subunits. Exposure of these cells to NGF (PC12+ cells) increased the amount
of 68,000-dalton NF subunits 8-fold, VF protein 3-fold, and 150,000- and
200,000-dalton NF subunits 2-fold. The ratio of VF to 68,000-dalton NF
proteins in PC12- versus PC12+ cells decreased from 3.0 to 1.5. Both VF and
68,000-dalton NF subunits were arranged in juxtanuclear "ball-like"
configurations and both were present in neurites of PC12+ cells. The
distribution of 150,000- and 200,000-dalton NF subunits was diffuse with
perinuclear stippling and only occasional, weakly fluorescent "balls."
After perturbation of the PC12 cell cytoskeleton, 68,000-dalton NF subunits
and VF redistributed together and, thus, may exist as heteropolymers.
Finally, the increased expression of NF and VF proteins was specific for
NGF since they could not be induced by other hormones or "growth" factors.
We conclude that PC12 cells constitute a model system for studies of NF and
VF expression, assembly, and interactions.