The proteinase-activated receptor-2 mediates phagocytosis in a Rho-dependent manner in human keratinocytes.
Recent work shows that the G-protein-coupled receptor proteinase activated receptor-2 activates signals that stimulate melanosome uptake in keratinocytes in vivo and in vitro. The Rho family of GTP-binding proteins is involved in cytoskeletal remodeling during phagocytosis. We show that proteinase-activated receptor-2 mediated phagocytosis in human keratinocytes is Rho dependent and that proteinase-activated receptor-2 signals to activate Rho. In contrast, Rho activity did not affect either proteinase-activated receptor-2 activity or mRNA and protein levels. We explored the signaling mechanisms of proteinase-activated receptor-2 mediated Rho activation in human keratinocytes and show that activation of proteinase-activated receptor-2, either through specific proteinase-activated receptor-2 activating peptides or through trypsinization, elevates cAMP in keratinocytes. Proteinase-activated receptor-2 mediated Rho activation was pertussis toxin insensitive and independent of the protein kinase A signaling pathway. These data are the first to show that proteinase-activated receptor-2 mediated phagocytosis is Rho dependent and that proteinase-activated receptor-2 signals to Rho and cAMP in keratinocytes. Because phagocytosis of melanosomes is recognized as an important mechanism for melanosome transfer to keratinocytes, these results suggest that Rho is a critical signaling intermediate in melanosome uptake in keratinocytes.
Scott
Glynis
G
Department of Dermatology, University of Rochester School of Medicine, 601 Elmwood Avenue, Rochester, NY 14618, USA. Glynis.Scott@urmc.rochester.edu
Leopardi
Sonya
S
Parker
Lorelle
L
Babiarz
Laura
L
Seiberg
Miri
M
Han
Rujiing
R
D002460:Cell Line; D000242:Cyclic AMP / Q000378:metabolism; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D000078404:Epidermal Cells; D044365:GTP-Binding Protein alpha Subunits, G12-G13; D015870:Gene Expression / Q000502:physiology; D020962:Heterotrimeric GTP-Binding Proteins / Q000235:genetics / Q000378:metabolism; D006801:Humans; D015603:Keratinocytes / Q000166:cytology* / Q000201:enzymology*; D020460:Melanosomes / Q000502:physiology; D037342:Pertussis Toxin / Q000494:pharmacology; D010587:Phagocytosis / Q000502:physiology*; D044464:Receptor, PAR-2; D018179:Receptors, Thrombin / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction / Q000502:physiology; D012880:Skin Pigmentation / Q000502:physiology*; D020741:rho GTP-Binding Proteins / Q000235:genetics / Q000378:metabolism*
D004268:DNA-Binding Proteins; D044464:Receptor, PAR-2; D018179:Receptors, Thrombin; D000242:Cyclic AMP; D037342:Pertussis Toxin; D017868:Cyclic AMP-Dependent Protein Kinases; D044365:GTP-Binding Protein alpha Subunits, G12-G13; D020962:Heterotrimeric GTP-Binding Proteins; D020741:rho GTP-Binding Proteins