Journal of Neuroscience, Vol 5, 1239-1245, Copyright © 1985 by Society for Neuroscience
Comparison of labeled heat shock proteins in neuronal and non-neuronal cells of Aplysia californica
SG Greenberg and RJ Lasek
Aplysia californica has been used to study the protein synthetic response
of nervous tissue to stress induced by elevated temperatures. The abdominal
and pleural ganglia as well as associated connectives were exposed to
various temperatures for 30 min, labeled with [33S]methionine at room
temperature, and then analyzed by sodium dodecyl sulfate gel
electrophoresis. All cells examined responded to temperatures of greater
than 31 degrees C by a reduction in levels of labeled actin, as well as by
the enhanced labeling of proteins with apparent Mr of 70,000 and 110,000.
Two-dimensional electrophoresis indicated that the molecular weight and
isoelectric focusing properties are similar to the heat shock proteins
(HSPs) observed in other systems. In addition to these major HSPs,
heat-induced proteins with molecular weights ranging from 70,000 to 90,000
were highly labeled in the neurosecretory bag cells. Further cell
type-specific differences in the protein synthetic response to elevated
temperatures were revealed by quantitation of the major HSPs. Levels of
labeled HSPs were significantly lower in ganglion cells as compared to the
non-neuronal connective cells. In addition, the decrease in actin levels
appeared to be less dramatic in the ganglion cells. Analysis of the
cellular compartmentalization of HSPs suggests that both neurons and glia
are capable of HSP synthesis. Studies in the squid have demonstrated that
HSPs are transferred from adaxonal glia into the axoplasm (Tytell, M., S.
G. Greenberg, and R. J. Lasek, unpublished observation).(ABSTRACT TRUNCATED
AT 250 WORDS)