Protein kinase C isoforms differentially control lacrimal gland functions.

Abstract

Lacrimal gland protein secretion is primarily under the control of cholinergic muscarinic and αl-adrenergic receptors.1 Cholinergic agonists are coupled to the activation of phospholipase C (PLC),2 which leads to the production of two second messenger molecules: inositol 1,4,5-trisphosphate (IP3) and diacylglycerol (DAG). IP3 increases the cytoplasmic concentration of calcium ([Ca2+]i) and DAG activates protein kinase C (PKC), two events that are thought to trigger protein secretion.1 Lacrimal gland αl-adrenergic receptors are of particular interest. Unlike those in other tissues, they are not coupled to the PLC pathway, although their activation leads to a slight increase in [Ca2+]i.3 We have also shown that these receptors are not linked to the activation of phospholipase D in lacrimal gland acini.4 Thus the transduction pathway(s) used by the α1-adrenergic receptors to trigger lacrimal gland protein secretion remains to be identified.KeywordsAcinar CellApical MembranePhorbol EsterMyoepithelial CellLacrimal GlandThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.