v-Src accelerates spontaneous motility via phosphoinositide 3-kinase, phospholipase C and phospholipase D, but abrogates chemotaxis in Rat-1 and MDCK cells.
In Rat-1 fibroblasts, v-Src causes a profound remodelling of cortical actin cytoskeleton. This transformation includes membrane ruffling, a hallmark of the leading edge in migrating cells, and results from activation of phosphoinositide 3-kinase (PI 3-kinase), phospholipase C (PLC) and phospholipase D (PLD). We therefore reexamined whether motility is constitutively triggered by v-Src and studied whether this response is controlled by the same signalling pathway. The study was performed using Rat-1/tsLA29 and MDCK/tsLA31 cells, each harbouring a different thermosensitive v-Src kinase, active at 34 degrees C but inactivated at 40 degrees C. In both cell lines, overnight v-Src activation induced transformation and accelerated spontaneous motility by approximately twofold, as evidenced by wound-healing assay and by single-cell track, time-lapse recording in Dunn chambers. Inhibitors of PI 3-kinase, PLC and PLD selectively abrogated acceleration of motility by v-Src. Since mechanisms that co-ordinate spontaneous, as distinct from oriented, cell migration are separable, we further analysed in Dunn chambers chemotactic response of Rat-1/tsLA29 cells to PDGF and of MDCK/tsLA31 cells to EGF. In both cases, v-Src decreased the steady-state level of growth factor receptors at the cell surface twofold, and abrogated movement directionality at comparable level of occupancy as in non-transformed cells. The burst of pinocytosis in response to growth factors was also abolished by v-Src. Altogether, these results indicate that v-Src triggers motility in a PI 3-kinase-, PLC- and PLD-dependent manner, but abrogates directionality by suppressing polarised signalling downstream of growth factor receptors.
Platek
Anna
A
CELL Unit, Christian de Duve Institute of Cellular Pathology, Université catholique de Louvain, UCL 75.41, Avenue Hippocrate, 75, 1200 Bruxelles, Belgium.
Mettlen
Marcel
M
Camby
Isabelle
I
Kiss
Robert
R
Amyere
Mustapha
M
Courtoy
Pierre J
PJ
D000199:Actins / Q000378:metabolism; D000818:Animals; D000440:Butanols / Q000378:metabolism; D002460:Cell Line; D002465:Cell Movement / Q000502:physiology*; D002633:Chemotaxis / Q000502:physiology*; D003599:Cytoskeleton / Q000378:metabolism; D004705:Endocytosis; D004791:Enzyme Inhibitors / Q000378:metabolism; D005347:Fibroblasts / Q000166:cytology / Q000378:metabolism; D006133:Growth Substances / Q000378:metabolism; D051379:Mice; D015688:Oncogene Protein pp60(v-src) / Q000235:genetics / Q000378:metabolism*; D010641:Phenotype; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism*; D010739:Phospholipase D / Q000378:metabolism*; D011500:Protein Synthesis Inhibitors / Q000378:metabolism; D051381:Rats; D015398:Signal Transduction / Q000502:physiology; D010738:Type C Phospholipases / Q000378:metabolism*
D000199:Actins; D000440:Butanols; D004791:Enzyme Inhibitors; D006133:Growth Substances; D011500:Protein Synthesis Inhibitors; D019869:Phosphatidylinositol 3-Kinases; D015688:Oncogene Protein pp60(v-src); D010738:Type C Phospholipases; D010739:Phospholipase D