Podoplanin binds ERM proteins to activate RhoA and promote epithelial-mesenchymal transition.
Podoplanin is a small membrane mucin expressed in tumors associated with malignant progression. It is enriched at cell-surface protrusions where it colocalizes with members of the ERM (ezrin, radixin, moesin) protein family. Here, we found that human podoplanin directly interacts with ezrin (and moesin) in vitro and in vivo through a cluster of basic amino acids within its cytoplasmic tail, mainly through a juxtamembrane dipeptide RK. Podoplanin induced an epithelial-mesenchymal transition in MDCK cells linked to the activation of RhoA and increased cell migration and invasiveness. Fluorescence time-lapse video observations in migrating cells indicate that podoplanin might be involved in ruffling activity as well as in retractive processes. By using mutant podoplanin constructs fused to green fluorescent protein we show that association of the cytoplasmic tail with ERM proteins is required for upregulation of RhoA activity and epithelial-mesenchymal transition. Furthermore, expression of either a dominant-negative truncated variant of ezrin or a dominant-negative mutant form of RhoA blocked podoplanin-induced RhoA activation and epithelial-mesenchymal transition. These results provide a mechanistic basis to understand the role of podoplanin in cell migration or invasiveness.
Martín-Villar
Ester
E
Instituto de Investigaciones Biomédicas Alberto Sols, Consejo Superior de Investigaciones Científicas (CSIC)-Universidad Autónoma de Madrid (UAM), 28029 Madrid, Spain.
Megías
Diego
D
Castel
Susanna
S
Yurrita
Maria Marta
MM
Vilaró
Senén
S
Quintanilla
Miguel
M
D000818:Animals; D015153:Blotting, Western; D002460:Cell Line; D002465:Cell Movement; D003598:Cytoskeletal Proteins / Q000378:metabolism*; D004285:Dogs; D004847:Epithelial Cells / Q000378:metabolism / Q000473:pathology*; D005455:Fluorescent Antibody Technique; D006367:HeLa Cells; D006801:Humans; D007668:Kidney / Q000378:metabolism; D008562:Membrane Glycoproteins / Q000235:genetics / Q000378:metabolism*; D008565:Membrane Proteins / Q000378:metabolism*; D008648:Mesoderm / Q000378:metabolism / Q000473:pathology*; D008840:Microfilament Proteins / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014945:Wound Healing; D020742:rhoA GTP-Binding Protein / Q000235:genetics / Q000378:metabolism*; D000099149:Ezrin; D000098853:Podoplanin
D003598:Cytoskeletal Proteins; D008562:Membrane Glycoproteins; D008565:Membrane Proteins; D008840:Microfilament Proteins; D020742:rhoA GTP-Binding Protein; D000099149:Ezrin; C117468:PDPN protein, human; D000098853:Podoplanin; C071058:moesin; C071776:radixin