INVESTIGADORES
ARREGUI Carlos Oscar
artículos
Título:
Characterization of neural cell adhesion sites: Point contacts are the sites of interaction between integrins and the cytoskeleton in PC12 cells.
Autor/es:
CARLOS OSCAR ARREGUI; CARBONETTO, S; MCKERRACHER, L
Revista:
JOURNAL OF NEUROSCIENCE
Editorial:
Society for Neuroscience
Referencias:
Año: 1994 vol. 14 p. 6967 - 6977
ISSN:
0270-6474
Resumen:
As developing or regenerating neurons grow, their axons
seek cues in the extracellular matrix that are recognized by
integrin receptors. To understand the regulation and structure
of neural integrin complexes, we have examined the
association of two functionally important integrins, alb1 and
a3b1, within PC1 2 cells. Detergent-resistant cytoskeletal
ghosts were prepared from PC12 cells and examined by
immunoblotting. In cells maintained in suspension the al,
a3, and b1integrin subunits were solubilized by Triton X- 100
detergent. In contrast, when cells were grown on collagen
or laminin about 50% of the al and b1 subunits were retained
with the cytoskeleton, but a3 remained soluble. Confocal
immunofluorescence microscopy of whole cells demonstrated
that all three integrin subunits were expressed in
a punctate pattern on the cell surface in point contacts. Point
contacts were also found to be the predominant adhesion
structure of dorsal root ganglion neurons. After detergent
extraction of PC12 cells, the point contacts remained only
at the cell-substrate interface. Vinculin, which is found consistently
in focal contacts on non-neural cells, showed only
a partial colocalization with the point contacts, being expressed
mainly at the tips of filopodia and the periphery of
cell bodies. Talin showed no obvious codistribution with bl
integrin immunoreactivity in point contacts. Immunoreactivity
to pl25FAK was not detected in PC 12 cells, although astrocytes,
which have both focal contacts and point contacts,
have p125FAK only at focal contacts. These observations,
together with previous data (Turner et al., 1989; Tawil et al.,
1993), suggest that point contacts are functional adhesion
sites and are structurally distinct from focal contacts found
in non-neuronal cells.