D. Zoukhri et al., IMMUNOLOCALIZATION OF LACRIMAL GLAND PKC ISOFORMS - EFFECT OF PHORBOLESTERS AND CHOLINERGIC AGONISTS ON THEIR CELLULAR-DISTRIBUTION, The Journal of membrane biology, 157(2), 1997, pp. 169-175
In previous studies, we showed that lacrimal gland acini express three
isoforms of protein kinase C (PKC): PKC alpha-delta, and -epsilon. In
the present study, we report the identification of two other PKC isof
orms, namely PKC mu and -iota/lambda. Using immunofluorescence techniq
ues, we showed that these isoforms are differentially located. PKC alp
ha and -mu showed the most prominent membrane localization, whereas PK
C delta, -epsilon and -iota/lambda were mainly cytosolic. Using cell f
ractionation and western blotting techniques, we showed that the phorb
ol ester, phorbol 12, 13-dibutyrate (PdBu, 10(-6) M), translocated all
PKC isoforms, except PKC iota/lambda, from the soluble fraction into
the particulate fraction. The effect was maximum at 5 min and persiste
d at 10 min. PKC epsilon was the most responsive to PdBu reaching almo
st maximal translocation at a PdBu concentration as low as 10(-9) M. T
he cholinergic agonist, carbachol (10(-5) and 10(-3) M), induced trans
location which was transient for PKC delta, and -mu, but persisted for
10 min for PKC epsilon. Carbachol did not translocate PKC alpha and,
like PdBu, did not translocate PKC iota/lambda. We concluded that lacr
imal gland PKC isoforms are differentially localized and that they tra
nslocate differentially in response to phorbol esters and cholinergic
agonists.