Protein kinase C regulation of cell spreading in the molluscan Biomphalaria glabrata embryonic (Bge) cell line

Cellular adhesion and spreading are critical components involved in the pro cesses of cell and tissue development, and immune responses in molluscs, bu t at present, little is known regarding the signaling pathways involved in these basic cellular functions. In the present study, the molluscan Biompha laria glabrata embryonic (Bge) cell line was used as an in vitro model to s tudy the signal transduction pathways regulating molluscan cell adhesion an d spreading behavior. Western blot analysis using antibodies specific to mi togen-activated protein kinase (MAPK) revealed the presence of an MAPK-like immunoreactive protein in Bge cells, that was phosphorylated upon exposure to phorbol myristate acetate (PMA). Moreover, Bge cell treatment with inhi bitors of protein kinase C (PKC), Ras and MAPK kinase (Mek) suppressed PMA- induced expression of activated MAPK, suggesting that PKC-, Ras- and Mek-li ke molecules may be acting upstream of MAPK. Similarly, in vitro Bge cell-s preading assays were performed in conjunction with the same panel of inhibi tors to determine the potential involvement of PKC, Ras and Mek in cellular adhesion/spreading. Results revealed a similar pattern of inhibition of ce ll-spreading behavior strongly implying that the Bge cell spreading also ma y be regulated through a MAPK-associated signal transduction pathway(s) inv olving proteins similar to PKC, Ras and Mek. (C) 2001 Elsevier Science BN. All rights reserved.