The Journal of Neuroscience, May 15, 2002, 22(10):3890-3897
Nerve Growth Factor-Induced Differentiation Changes the Cellular
Organization of Regulated Peptide Release by PC12 Cells
Yuen-Keng
Ng1, *,
Xinghua
Lu1, *,
Simon C.
Watkins2,
Graham C. R.
Ellis-Davies3, and
Edwin S.
Levitan1
Departments of 1 Pharmacology and 2 Cell
Biology and Physiology, University of Pittsburgh, Pittsburgh,
Pennsylvania 15261, and 3 Department of Pharmacology and
Physiology, MCP/Hahnemann University, Philadelphia, Pennsylvania
19102
PC12 cells, like endocrine chromaffin cells, undergo neuronal-like
differentiation in response to nerve growth factor (NGF). Here we
report that this phenotype conversion produces major changes in release
of a green fluorescent protein-tagged neuropeptide-hormone. First, the
spatial distribution of the releasable pool is altered; peptide release
from untreated cells is supported predominantly by membrane-proximal
vesicles, whereas a diffuse pool at the ends of processes is used by
NGF-treated cells. Second, the time course of release evoked by
photolysis of caged Ca2+ is faster after
differentiation. High-resolution measurements suggest that a slow step
before membrane fusion dominates the kinetics of release in untreated
cells. Finally, the effect of actin microfilament depolymerization on
total release is altered by NGF treatment. This implies that the
mechanism that limits the size of the releasable pool is altered by
phenotype conversion. Therefore, the cellular organization of peptide
release is plastic and changes in response to NGF. This flexibility may
be used to generate cell-specific release properties.
Key words:
neuropeptide release; hormone release; GFP; caged
calcium; actin; secretory vesicle; neuronal differentiation; releasable
pool
*
Y.-K.N. and X.L. contributed equally to this work.
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