title: Immunolocalization of lacrimal gland PKC isoforms. Effect of phorbol esters and cholinergic agonists on their cellular distribution.
abstract: In previous studies, we showed that lacrimal gland acini express three isoforms of protein kinase C (PKC): PKCalpha,-delta, and -epsilon. In the present study, we report the identification of two other PKC isoforms, namely PKCmu and -iota/lambda. Using immunofluorescence techniques, we showed that these isoforms are differentially located. PKCalpha and -mu showed the most prominent membrane localization, whereas PKCdelta, -epsilon and -iota/lambda were mainly cytosolic. Using cell fractionation and western blotting techniques, we showed that the phorbol ester, phorbol 12,13-dibutyrate (PdBu, 10(-6) M), translocated all PKC isoforms, except PKCiota/lambda, from the soluble fraction into the particulate fraction. The effect was maximum at 5 min and persisted at 10 min. PKCepsilon was the most responsive to PdBu reaching almost maximal translocation at a PdBu concentration as low as 10(-9) M. The cholinergic agonist, carbachol (10(-5) and 10(-3) M), induced translocation which was transient for PKCdelta, and -mu, but persisted for 10 min for PKCepsilon. Carbachol did not translocate PKCalpha and, like PdBu, did not translocate PKCiota/lambda. We concluded that lacrimal gland PKC isoforms are differentially localized and that they translocate differentially in response to phorbol esters and cholinergic agonists.
authors.affiliation: Schepens Eye Research Institute and Department of Ophthalmology, Harvard Medical School, 20 Staniford Street, Boston, MA 02114, USA.
authors.forename: D
authors.initials: D
authors.lastname: Zoukhri
authors.forename: R R
authors.initials: RR
authors.lastname: Hodges
authors.forename: S
authors.initials: S
authors.lastname: Willert
authors.forename: D A
authors.initials: DA
authors.lastname: Dartt
mesh_terms: D000818:Animals; D015153:Blotting, Western; D002217:Carbachol / Q000494:pharmacology*; D002273:Carcinogens / Q000494:pharmacology*; D002458:Cell Fractionation; D004591:Electrophoresis, Polyacrylamide Gel; D019084:Fluorescent Antibody Technique, Indirect; D007527:Isoenzymes / Q000378:metabolism*; D007765:Lacrimal Apparatus / Q000187:drug effects / Q000201:enzymology*; D008297:Male; D018721:Muscarinic Agonists / Q000494:pharmacology*; D015240:Phorbol 12,13-Dibutyrate / Q000494:pharmacology*; D011493:Protein Kinase C / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar
chemical_list: D002273:Carcinogens; D007527:Isoenzymes; D018721:Muscarinic Agonists; D015240:Phorbol 12,13-Dibutyrate; D002217:Carbachol; D011493:Protein Kinase C