Ck. Thodeti et al., The epsilon isoform of protein kinase C is involved in regulation of the LTD4-induced calcium signal in human intestinal epithelial cells, EXP CELL RE, 262(2), 2001, pp. 95-103
We investigated the potential roles of specific isoforms of protein kinase
C (PKC) in the regulation of leukotriene Da-induced Ca2+ signaling in the i
ntestinal epithelial cell line Int 407. RT-PCR and Western blot analysis re
vealed that these cells express the PKC isoforms alpha, beta II, delta, eps
ilon, zeta, and mu, but not betaI, gamma, eta, or theta. The inflammatory m
ediator leukotriene D-4 (LTD4) caused the TPA-sensitive PKC isoforms alpha,
delta, and epsilon, but not beta II, to rapidly translocate to a membrane-
enriched fraction. The PKC inhibitor GF109203X at 30 muM but not 2 muM sign
ificantly impaired the LTD4-induced Ca2+ signal, indicating that the respon
se involves a novel PKC isoform, such as delta or epsilon, but not alpha. L
TD4-induced Ca2+ signaling was significantly suppressed in cells pretreated
with TPA for 15 min and was abolished when the pretreatment was prolonged
to 2 h. Immunoblot analysis revealed that the reduction in the LTD4-induced
calcium signal coincided with a reduction in the cellular content of PKC e
psilon and, to a Limited extent, PKC delta. LTD4-induced Ca2+ signaling was
also markedly suppressed by microinjection of antibodies against PKC epsil
on but not PKC delta. These data suggest that PKC epsilon plays a unique ro
le in regulation of the LTD4-dependent Ca2+ signal in intestinal epithelial
cells. (C) 2001 Academic Press.