Activation of kinin B receptor triggers differentiation of cultured human keratinocytes.
BACKGROUND
Keratinocyte life span is modulated by receptors that control proliferation and differentiation, key processes during cutaneous tissue repair. The kinin B(1) receptor (B(1)R) has been reported in normal and pathological human skin, but so far there is no information about its role in keratinocyte biology.


OBJECTIVE
To determine the consequence of kinin B(1)R stimulation on tyrosine phosphorylation, a key signalling mechanism involved in keratinocyte proliferation and differentiation.


METHODS
Subconfluent primary cultures of human keratinocytes were used to investigate tyrosine phosphorylation, epidermal growth factor receptor (EGFR) transactivation, cell proliferation and keratinocyte differentiation. Cell proliferation was assessed by measuring bromodeoxyuridine incorporation whereas assessment of cell differentiation was based on the expression of filaggrin, cytokeratin 10 (CK10) and involucrin.


RESULTS
The major proteins phosphorylated, after B(1)R stimulation, were of molecular mass 170, 125, 89 and 70 kDa. The 170- and 125-kDa proteins were identified as EGFR and p125(FAK), respectively. Phosphorylation was greatly reduced by GF109203X and by overexposure of keratinocytes to phorbol 12-myristate 13-acetate, indicating the participation of protein kinase C. B(1)R stimulation did not increase [Ca(2+)]i, but triggered EGFR transactivation, an event that involved phosphorylation of Tyr(845), Tyr(992) and Tyr(1068) of EGFR. B(1)R stimulation did not elicit keratinocyte proliferation, but triggered cell differentiation, visualized as an increase of filaggrin, CK10 and involucrin. Blockade of EGFR tyrosine kinase by AG1478, before B(1)R stimulation, produced an additional increase in filaggrin expression.


CONCLUSIONS
The kinin B(1)R may contribute to keratinocyte differentiation and migration by triggering specific tyrosine signalling pathways or by interacting with the ErbB receptor family.
Matus
C E
CE
Laboratorio de Patologia Celular, Instituto de Anatomía, Histología y Patología, Universidad Austral de Chile, Casilla 567, Isla Teja, Valdivia, Chile.
Ehrenfeld
P
P
Pavicic
F
F
Sarmiento
J M
JM
Astroza
A
A
Sanchez
T
T
Salem
C
C
Concha
M
M
Vidal
M A
MA
Gonzalez
C B
CB
Figueroa
C D
CD
D002454:Cell Differentiation; D002478:Cells, Cultured / Q000378:metabolism; D066246:ErbB Receptors / Q000378:metabolism*; D000091344:Filaggrin Proteins; D006801:Humans; D015603:Keratinocytes / Q000166:cytology* / Q000378:metabolism; D007705:Kinins / Q000378:metabolism*; D020935:MAP Kinase Signaling System / Q000502:physiology; D043783:Receptor, Bradykinin B1 / Q000378:metabolism*; D043782:Receptor, Bradykinin B2 / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000379:methods; D012867:Skin / Q000378:metabolism
C000717249:FLG protein, human; D000091344:Filaggrin Proteins; D007705:Kinins; D043783:Receptor, Bradykinin B1; D043782:Receptor, Bradykinin B2; D066246:ErbB Receptors