Gg. Gu et S. Singh, MODULATION OF THE DIHYDROPYRIDINE-SENSITIVE CALCIUM CHANNELS IN DROSOPHILA BY A PHOSPHOLIPASE C-MEDIATED PATHWAY, Journal of neurobiology, 33(3), 1997, pp. 265-275
Disruption of phospholipase C-beta (PLC) by the norpA mutations of Dro
sophila renders flies blind by affecting the light-evoked photorecepto
r potential. We report here that the norpA-coded PLC modulates the 1,4
-dihydropyridine (DHP)-sensitive Ca2+ channels in lai val muscles. The
DHP-sensitive current was reduced in the norpA mutants. Application o
f 1 mu M phorbol 12-myristate 13-acetate (TPA) and 1 mu M phorbol 12,1
3-didecanoate (PDD), activators of protein kinase C (PKC), rescued the
current in the mutant fibers without significantly affecting the norm
al current. 4 alpha-phorbol 12,13-didecanoate (4 alpha PDD), an inacti
ve analog of PDD, did not affect either the normal or the mutant curre
nt. One micromolar bisindolylmaleimide (BIM), an inhibitor of PKC, red
uced the current in the normal fibers without affecting the mutant cur
rent. 300 mu M sn-1,2-dioctanoyl-glycerol (DOG), an analog of diacylgl
ycerol (DAG), increased the current in the mutant fibers. These experi
ments suggest that the DHP-sensitive Ca2+ channels in Drosophila may b
e modulated by the PLC-DAG-PKC pathway, and that the same PLC isozyme
which is involved in phototransduction in the adult flies may also mod
ulate muscle Ca2+ channels in the larval stage of development. (C) 199
7 John Wiley & Sons, Inc. J Neurobiol.