The class II phosphoinositide 3-kinase PI3K-C2beta regulates cell migration by a PtdIns3P dependent mechanism.
The biological and pathophysiological significance of class II phosphoinositide 3-kinase enzyme expression currently remains unclear. Using an in vitro scrape wound assay and time-lapse video microscopy, we demonstrate that cell motility is increased in cultures expressing recombinant PI3K-C2beta enzyme. In addition, overexpression of PI3K-C2beta transiently decreased cell adhesion, stimulated the formation of cytoplasmic processes, and decreased the rate of cell proliferation. Consistent with these observations, expression of PI3K-C2beta also decreased expression of alpha4 beta1 integrin subunits. Using asynchronous cultures, we show that endogenous PI3K-C2beta is present in lamellipodia of motile cells. When cells expressing recombinant PI3K-C2beta were plated onto fibronectin, cortical actin staining increased markedly and actin rich lamellipodia and filopodia became evident. Overexpression of a 2xFYVE(Hrs) domain fusion protein abolished this response demonstrating that the effect of PI3K-C2beta on the reorganization of actin filaments is dependent upon PtdIns3P. Finally, overexpression of PI3K-C2beta increased GTP loading of Cdc42. Our data demonstrates for the first time, that PI3K-C2beta plays a regulatory role in cell motility and that the mechanism by which it reorganizes the actin cytoskeleton is dependent upon PtdIns3P production.
Domin
Jan
J
Division of Medicine, Imperial College, London. j.domin@imperial.ac.uk
Harper
Lisa
L
Aubyn
Deborah
D
Wheeler
Matthew
M
Florey
Oliver
O
Haskard
Dorian
D
Yuan
Ming
M
Zicha
Daniel
D
D000199:Actins / Q000502:physiology; D000818:Animals; D002417:Cattle / Q000097:blood; D002448:Cell Adhesion / Q000187:drug effects; D002460:Cell Line; D002465:Cell Movement / Q000187:drug effects* / Q000502:physiology*; D049109:Cell Proliferation / Q000187:drug effects; D002477:Cells / Q000648:ultrastructure; D058541:Class II Phosphatidylinositol 3-Kinases; D003599:Cytoskeleton / Q000187:drug effects; D005312:Fetal Blood; D006160:Guanosine Triphosphate / Q000378:metabolism; D006801:Humans; D019869:Phosphatidylinositol 3-Kinases / Q000494:pharmacology*; D018129:Phosphatidylinositol Phosphates / Q000502:physiology*; D010766:Phosphorylation / Q000187:drug effects; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D011994:Recombinant Proteins / Q000494:pharmacology; D014018:Tissue Distribution; D020764:cdc42 GTP-Binding Protein / Q000097:blood / Q000378:metabolism; D020744:rac GTP-Binding Proteins / Q000378:metabolism
D000199:Actins; D018129:Phosphatidylinositol Phosphates; D011994:Recombinant Proteins; C055525:phosphatidylinositol 3-phosphate; D006160:Guanosine Triphosphate; D019869:Phosphatidylinositol 3-Kinases; D058541:Class II Phosphatidylinositol 3-Kinases; C502616:PIK3C2B protein, human; D051057:Proto-Oncogene Proteins c-akt; D020764:cdc42 GTP-Binding Protein; D020744:rac GTP-Binding Proteins