PKCalpha regulates beta1 integrin-dependent cell motility through association and control of integrin traffic.
Protein kinase C (PKC) has been implicated in integrin-mediated spreading and migration. In mammary epithelial cells there is a partial co-localization between beta1 integrin and PKCalpha. This reflects complexes between these proteins as demonstrated by fluorescense resonance energy transfer (FRET) monitored by fluorescence lifetime imaging microscopy and also by coprecipitation. Constitutive complexes are observed for the intact PKCalpha and also form with the regulatory domain in an activation-dependent manner. Expression of PKCalpha causes upregulation of beta1 integrin on the cell surface, whereas stimulation of PKC induces internalization of beta1 integrin. The integrin initially traffics to an endosomal compartment in a Ca(2+)/PI 3-kinase/dynamin I-dependent manner and subsequently enters an endocytic recycling pathway. This induction of endocytosis by PKCalpha is a function of activity and is not observed for the regulatory domain. PKCalpha, but not PKCalpha regulatory domain expression stimulates migration on beta1 integrin substrates. This PKCalpha-enhanced migratory response is inhibited by blockade of endocytosis.
Protein Phosphorylation Laboratory, Imperial Cancer Research Fund, 44 Lincoln's Inn Fields, London WC2A 3PX, UK.
T
T
Ng
D
D
Shima
A
A
Squire
P I
PI
Bastiaens
S
S
Gschmeissner
M J
MJ
Humphries
P J
PJ
Parker
D002118:Calcium / Q000378:metabolism; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism; D002465:Cell Movement / Q000187:drug effects; D004705:Endocytosis; D011992:Endosomes / Q000187:drug effects / Q000378:metabolism; D004789:Enzyme Activation / Q000187:drug effects; D016326:Extracellular Matrix Proteins / Q000378:metabolism; D006801:Humans; D019012:Integrin beta1 / Q000378:metabolism*; D008856:Microscopy, Fluorescence; D016253:Microscopy, Immunoelectron; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D000081082:Phosphoinositide-3 Kinase Inhibitors; D011485:Protein Binding / Q000187:drug effects; D011493:Protein Kinase C / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D011554:Pseudopodia / Q000187:drug effects / Q000378:metabolism; D011990:Receptors, Transferrin / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D014162:Transfection; D014407:Tumor Cells, Cultured
D002118:Calcium; D016326:Extracellular Matrix Proteins; D019012:Integrin beta1; D019869:Phosphatidylinositol 3-Kinases; D000081082:Phosphoinositide-3 Kinase Inhibitors; D011493:Protein Kinase C; D011990:Receptors, Transferrin; D011993:Recombinant Fusion Proteins; D013755:Tetradecanoylphorbol Acetate