INVESTIGADORES
CAPANI Francisco
congresos y reuniones científicas
Título:
Localization of actin in rat pinceau.
Autor/es:
BOBIK, M., CAPANI, F.; ELLISMAN, M. H. ; MARTONE, M. E.
Lugar:
New Orleans
Reunión:
Congreso; Society for Neuroscience Meeting; 2000
Resumen:
The pinceau is a
cerebellar structure formed by basket cell (BC) axon collaterals
converging on the Purkinje cell axon initial segment (PCIS). In a
previous study on the distribution of F-actin in the rat brain (Capani
et al., submitted), we noted that the pinceau area was particularly
enriched in F-actin. To determine the cellular elements stained for
F-actin, we employed correlated light and electron microscopy (EM) using
phalloidin-eosin, followed by fluorescence photooxidation.
Three-dimensional EM analysis using electron tomography established the
presence of actin in BC axons, particularly in those regions with high
density of synaptic vesicles. Some astrocytes enveloping the PCIS and
soma were also positive for actin. The most intense staining was found
in thin fibers, 0.15ìm in diameter, that coursed through the pinceau
region. These fibers had some characteristics of astrocytic processes,
but lacked velous extensions. We further studied the distribution of
F-actin using multilabel confocal microscopy. Actin labeling showed
almost complete colocalization with PSD95, and with the potassium
channel subunit Kv 3.2. Actin partially colocalized with GFAP, but
rarely colocalized with neurofilament protein, which stains the main
axons of pinceau fibers. Our results suggest that the terminal portions
of pinceau fibers and some astrocytic processes are characterized by
high concentrations of F-actin. The identity of the intensely stained
processes remains to be determined. Because actin plays a major role in
cell motility and maintaining cell architecture, the presence of high
concentrations of F-actin in pinceau raises the possibility that this
region is more dynamic than previously suspected.