Formation of a β1 integrin signaling complex in Schwann cells is independent of rho

• Published in: Glia 2003-01, Vol.41 (1), p.94-104
• Main Authors: Taylor, Anna R., Geden, Sandra E., Fernandez-Valle, Cristina
• Format: Article
• Language: English
• Subjects: Biological and medical sciences; differentiation; focal adhesion; Fundamental and applied biological sciences. Psychology; Isolated neuron and nerve. Neuroglia; myelination; Vertebrates: nervous system and sense organs
• ISSN: 0894-1491; 1098-1136
• DOI: 10.1002/glia.10170

Schwann cell adhesion to basal lamina is essential for peripheral nerve development. β1 integrin receptors for extracellular matrix cooperate with other receptors to transmit signals that coordinate cell cycle progression and initiation of differentiation, including myelin‐specific gene expression. In Schwann cell/sensory neuron cocultures, β1 integrins complex with focal adhesion kinase (FAK), fyn kinase, paxillin, and schwannomin in response to basal lamina adhesion. To study the assembly of this signaling complex in Schwann cells (SCs), we induced β1 integrin clustering on suspended cells using an immobilized antibody and recovered a complex containing β1 integrin, FAK, paxillin, and schwannomin. In adherent subconfluent cells, the proteins colocalized to filopodia, ruffling membranes and focal contacts. We assessed the role of rhoGTPase in the process of integrin complex assembly by introducing C3 transferase (C3T), a rho inhibitor, into the cells. Although C3T caused dose‐dependent morphological abnormalities, FAK, paxillin, and schwannomin were able to coimmunoprecipitate with β1 integrin. Additionally, colocalization of FAK, paxillin, and schwannomin with β1 integrin in filopodia and small focal contacts remained unchanged. We conclude that SCs do not require active rho to recruit signaling and structural proteins to β1 integrins clustered at the plasma membrane. Rho is required to establish large focal adhesions and to spread and stabilize plasma membrane extensions. GLIA 41:94–104, 2003. © 2003 Wiley‐Liss, Inc.