PKCalpha induces differentiation through ERK1/2 phosphorylation in mouse keratinocytes.
Epidermal keratinocyte differentiation is a tightly regulated stepwise process that requires protein kinase C (PKC) activation. Studies on cultured mouse keraitnocytes induced to differentiate with Ca2+ have indirectly implicated the involvement of PKCa isoform. When PKCalpha was overexpressed in undifferentiated keratinocytes using adenoviral system, expressions of differentiation markers such as loricrin, filaggrin, keratin 1 (MK1) and keratin 10 (MK10) were increased, and ERK1/2 phosphorylation was concurrently induced without change of other MAPK such as p38 MAPK and JNK1/2. Similarly, transfection of PKCalpha kinase active mutant (PKCalpha- CAT) in the undifferentiated keratinocyte, but not PKCbeta-CAT, also increased differentiation marker expressions. On the other hand, PKCalpha dominant negative mutant (PKCbeta-KR) reduced Ca2+ -mediated differentiation marker expressions, while PKCbeta-KR did not, suggesting that PKCalpha is responsible for keratinocyte differentiation. When downstream pathway of PKCalpha in Ca2+ -mediated differentiation was examined, ERK1/2, p38 MAPK and JNK1/2 phosphorylations were increased by Ca2+ shift. Treatment of keratinocytes with PD98059, MEK inhibitor, and SB20358, p38 MAPK inhibitor, before Ca2+ shift induced morphological changes and reduced expressions of differentiation markers, but treatment with SP60012, JNK1/2 inhibitor, did not change at all. Dominant negative mutants of ERK1/2 and p38 MAPK also inhibited the expressions of differentiation marker expressions in Ca2+ shifted cells. The above results indicate that both ERK1/2 and p38 MAPK may be involved in Ca2+ -mediated differentiation, and that only ERK1/2 pathway is specific for PKCalpha-mediated differentiation in mouse keratinocytes.
Seo
Haeng Ran
HR
Laboratory of Radiation Effect, Korea Institute of Radiological and Medical Sciences, 215-4 Gongneung-dong, Nowon-Ku, Seoul, 139-706, Korea.
Kwan
Yoo-Wook
YW
Cho
Chul-Koo
CK
Bae
Sangwoo
S
Lee
Su-Jae
SJ
Soh
Jae-Won
JW
Chung
Hee-Yong
HY
Lee
Yun-Sil
YS
D000818:Animals; D002118:Calcium / Q000494:pharmacology / Q000502:physiology; D002454:Cell Differentiation / Q000502:physiology; D000091344:Filaggrin Proteins; D007381:Intermediate Filament Proteins / Q000032:analysis / Q000378:metabolism; D015603:Keratinocytes / Q000166:cytology / Q000201:enzymology*; D008565:Membrane Proteins / Q000032:analysis / Q000378:metabolism; D051379:Mice; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism*; D048052:Mitogen-Activated Protein Kinase 3 / Q000378:metabolism*; D010766:Phosphorylation; D011493:Protein Kinase C / Q000235:genetics / Q000502:physiology*; D051571:Protein Kinase C-alpha; D048051:p38 Mitogen-Activated Protein Kinases / Q000378:metabolism
D000091344:Filaggrin Proteins; D007381:Intermediate Filament Proteins; D008565:Membrane Proteins; C064554:loricrin; C496630:Prkca protein, mouse; D011493:Protein Kinase C; D051571:Protein Kinase C-alpha; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D048051:p38 Mitogen-Activated Protein Kinases; D002118:Calcium