A signalling cascade involving PKC, Src and Cdc42 regulates podosome assembly in cultured endothelial cells in response to phorbol ester.
The involvement of Src, Cdc42, RhoA and PKC in the regulation of podosome assembly has been identified in various cell models. In endothelial cells, the ectopic expression of constitutively active mutants of Src or Cdc42, but not RhoA, induced the formation of podosomes. Short-term exposure to phorbol-12-myristate-13-acetate (PMA) induced the appearance of podosomes and rosettes after initial disruption of stress fibres. Molecular analysis of PMA-induced podosomes and rosettes revealed that their composition was identical to that of podosomes described in other models. Pharmacological inhibition and siRNA knock-down experiments revealed that both PKCalpha and PKCdelta isotypes were necessary for podosome assembly. However, only constitutively active PKCalpha could mimic PMA in podosome formation. Src, Cdc42 and RhoA were required downstream of PKCs in this process. Src could be positioned between PKC and Cdc42 in a linear cascade leading to podosome assembly. Using in vitro matrix degradation assays, we demonstrated that PMA-induced podosomes are endowed with proteolytic activities involving MT1-MMP-mediated activation of MMP2. Endothelial podosomes may be involved in subendothelial matrix degradation during endothelium remodelling in pathophysiological processes.
Tatin
Florence
F
Institut Européen de Chimie-Biologie, 2 rue Robert Escarpit, 33600 Pessac, France.
Varon
Christine
C
Génot
Elisabeth
E
Moreau
Violaine
V
D000199:Actins / Q000502:physiology; D002448:Cell Adhesion / Q000187:drug effects / Q000502:physiology; D002462:Cell Membrane / Q000187:drug effects / Q000502:physiology; D002478:Cells, Cultured; D003599:Cytoskeleton / Q000187:drug effects / Q000502:physiology; D004730:Endothelium, Vascular / Q000166:cytology / Q000502:physiology*; D006801:Humans; D010703:Phorbol Esters; D011493:Protein Kinase C / Q000502:physiology*; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology*; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D020764:cdc42 GTP-Binding Protein / Q000502:physiology*; D019061:src-Family Kinases / Q000502:physiology*
D000199:Actins; D010703:Phorbol Esters; D019061:src-Family Kinases; D011493:Protein Kinase C; D020764:cdc42 GTP-Binding Protein; D013755:Tetradecanoylphorbol Acetate