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Association of β1 Integrin with Focal Adhesion Kinase and Paxillin in Differentiating Schwann Cells

Authors :
Debora Bailey
Cristina Fernandez-Valle
Li-Mei Chen
Source :
The Journal of Neuroscience. 20:3776-3784
Publication Year :
2000
Publisher :
Society for Neuroscience, 2000.

Abstract

Schwann cells (SCs) differentiate into a myelinating cell when simultaneously adhering to an axon destined for myelination and basal lamina. We are interested in defining the signaling pathway activated by basal lamina. Using SC/sensory neuron (N) cocultures, we identified β1 integrin and F-actin as components of a pathway leading to myelin gene expression and myelination (Fernandez-Valle et al., 1994, 1997). Here, we show that focal adhesion kinase (FAK) and paxillin are constitutively expressed by SCs contacting axons in the absence of basal lamina. Tyrosine phosphorylation of FAK and paxillin increases as SCs form basal lamina and differentiate. FAK and paxillin specifically coimmunoprecipitate with β1 integrin in differentiating SC/N cocultures but not SC-only cultures. Paxillin coimmunoprecipitates with FAK and fyn kinase in differentiating SC/N cocultures. A subset of tyrosine-phosphorylated β1 integrin, FAK, and paxillin molecules reside in the insoluble, F-actin-rich fraction of differentiating cocultures. Cytochalasin D, an actin depolymerizing agent, decreases tyrosine phosphorylation of FAK and paxillin and their association with β1 integrin and causes a dose-dependent increase in the abundance of insoluble FAK and paxillin complexes. Collectively, our work indicates that β1 integrin, FAK, paxillin, and fyn kinase form an actin-associated complex in SCs adhering to basal lamina in the presence of axons. This complex may be important for initiating the process of SC differentiation into a myelinating cell.

Details

ISSN :
15292401 and 02706474
Volume :
20
Database :
OpenAIRE
Journal :
The Journal of Neuroscience
Accession number :
edsair.doi.dedup.....8a73abf4d51169851e268598ae8978c7
Full Text :
https://doi.org/10.1523/jneurosci.20-10-03776.2000