Role of extracellular matrix-cell interaction and epidermal growth factor (EGF) on EGF-receptors and actin cytoskeleton arrangement in infantile pituitary cells.
Epidermal growth factor (EGF) induces changes in cell morphology, actin cytoskeleton, and adhesion processes in cultured infantile pituitary cells. The extracellular matrix, through integrin engagement, collaborates with growth factors in cell signaling. We have examined the participation of collagen I/III and collagen plus fibronectin in the EGF response of infantile pituitary cells with respect to their cell morphology and actin cytoskeleton. As a comparison, we have used poly-lysine as a substrate. Infantile cells elicit the EGF response when they are associated with extracellular matrix proteins, but no response can be obtained with poly-lysine as the substrate. Cells acquire a flattened shape and organize their actin filaments and vinculin as in focal adhesions. Because the EGF receptor (EGFR) is linked to the actin cytoskeleton in other cells structuring a microdomain in cell signaling, we have investigated this association and substrate adhesion participation in infantile pituitary cells. The proportion of EGFR associated with the actin cytoskeleton is approximately 31%; no difference has been observed between the substrates used. Cells in suspension show actin-associated EGFR, suggesting an association independent of cell adhesion. However, no colocalization of EGFRs with actin fibers has been observed, suggesting an indirect association. Compared with beta(1)-integrin, which is linked to actin fibers through structural proteins, EGFR binds more strongly with the actin cytoskeleton. This study thus shows cell adhesion dependence on the EGF effect in the actin cytoskeleton arrangement; this is probably favored by the actin fiber/EGFR association that facilitates the cell signaling pathways for actin cytoskeleton organization in infantile pituitary cells.
Toral
Claudia
C
Department of Physiology, Biophysics and Neuroscience, CINVESTAV, Av. IPN No. 2508 Col. San Pedro Zacatenco, Mexico City, CP 07360, Mexico.
Solano-Agama
Carmen
C
Reyes-Márquez
Blanca
B
Sabanero
Myrna
M
Talamás
Patricia
P
González del Pliego
Margarita
M
Mendoza-Garrido
M Eugenia
ME
D000199:Actins / Q000378:metabolism*; D000818:Animals; D000833:Animals, Suckling; D002448:Cell Adhesion / Q000187:drug effects / Q000502:physiology; D048430:Cell Shape / Q000187:drug effects / Q000502:physiology; D002478:Cells, Cultured; D003599:Cytoskeleton / Q000187:drug effects / Q000378:metabolism*; D004815:Epidermal Growth Factor / Q000378:metabolism* / Q000494:pharmacology; D066246:ErbB Receptors / Q000378:metabolism*; D016326:Extracellular Matrix Proteins / Q000378:metabolism*; D005260:Female; D019085:Fluorescent Antibody Technique, Direct; D007091:Image Processing, Computer-Assisted; D008239:Lysine / Q000378:metabolism; D010903:Pituitary Gland, Anterior / Q000166:cytology / Q000378:metabolism*; D051381:Rats; D015398:Signal Transduction
D000199:Actins; D016326:Extracellular Matrix Proteins; D004815:Epidermal Growth Factor; D066246:ErbB Receptors; D008239:Lysine