Protein kinase d isoforms differentially modulate cofilin-driven directed cell migration.
BACKGROUND
Protein kinase D (PKD) enzymes regulate cofilin-driven actin reorganization and directed cell migration through both p21-activated kinase 4 (PAK4) and the phosphatase slingshot 1L (SSH1L). The relative contributions of different endogenous PKD isoforms to both signaling pathways have not been elucidated, sufficiently.


RESULTS
We here analyzed two cell lines (HeLa and MDA-MB-468) that express the subtypes protein kinase D2 (PKD2) and protein kinase D3 (PKD3). We show that under normal growth conditions both isoforms can form a complex, in which PKD3 is basally-active and PKD2 is inactive. Basal activity of PKD3 mediates PAK4 activity and downstream signaling, but does not significantly inhibit SSH1L. This signaling constellation was required for facilitating directed cell migration. Activation of PKD2 and further increase of PKD3 activity leads to additional phosphorylation and inhibition of endogenous SSH1L. Net effect is a dramatic increase in phospho-cofilin and a decrease in cell migration, since now both PAK4 and SSH1L are regulated by the active PKD2/PKD3 complex.


CONCLUSIONS
Our data suggest that PKD complexes provide an interface for both cofilin regulatory pathways. Dependent on the activity of involved PKD enzymes signaling can be balanced to guarantee a functional cofilin activity cycle and increase cell migration, or imbalanced to decrease cell migration. Our data also provide an explanation of how PKD isoforms mediate different effects on directed cell migration.
Department of Cancer Biology, Mayo Clinic, Jacksonville, Florida, United States of America.
Heike
H
Döppler
Department of Cancer Biology, Mayo Clinic, Jacksonville, Florida, United States of America.
Ligia I
LI
Bastea
Department of Cancer Biology, Mayo Clinic, Jacksonville, Florida, United States of America.
Sahra
S
Borges
Department of Cancer Biology, Mayo Clinic, Jacksonville, Florida, United States of America.
Samantha J
SJ
Spratley
Department of Cancer Biology, Mayo Clinic, Jacksonville, Florida, United States of America.
Sarah E
SE
Pearce
Department of Cancer Biology, Mayo Clinic, Jacksonville, Florida, United States of America.
Peter
P
Storz
D051339:Actin Depolymerizing Factors / Q000378:metabolism*; D002465:Cell Movement / Q000235:genetics / Q000502:physiology*; D006367:HeLa Cells; D006801:Humans; D015151:Immunoblotting; D047468:Immunoprecipitation; D046912:Multiprotein Complexes / Q000235:genetics / Q000378:metabolism*; D009841:Oligonucleotides / Q000235:genetics; D010749:Phosphoprotein Phosphatases / Q000378:metabolism; D010766:Phosphorylation; D020033:Protein Isoforms / Q000235:genetics / Q000378:metabolism*; D011493:Protein Kinase C / Q000235:genetics*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction / Q000235:genetics / Q000502:physiology*; D054462:p21-Activated Kinases / Q000378:metabolism
D051339:Actin Depolymerizing Factors; D046912:Multiprotein Complexes; D009841:Oligonucleotides; D020033:Protein Isoforms; C116367:PAK4 protein, human; C089212:protein kinase D; D054462:p21-Activated Kinases; D011493:Protein Kinase C; D010749:Phosphoprotein Phosphatases; C484329:SSH1 protein, human