Manipulation of phototransductive membrane turnover by crab photoreceptors in vitro: effects of two protein kinase activators, SC-9 and phorbol ester in the presence of a protein phosphatase inhibitor, okadaic acid.
1. Retinae of crabs, Leptograpsus variegatus, held on a 12:12 h light-dark cycle were prepared for culture in vitro shortly before light-off. After an hour in darkness to permit the assembly of "night" rhabdoms, retinae were exposed to various combinations of drugs: 1 microM okadaic acid (OKA); 60 microM SC-9; 10 microM phorbol, 12,13-diacetate (PDA). 2. The effects of the specific protein phosphatase inhibitor, OKA, are confirmed as light-dependent. Rhabdom sizes were not compromised by OKA, nor by either of the two protein kinase activators, SC-9 or PDA when each was deployed alone in darkness. 3. In combination with OKA, PDA induced demolition of rhabdoms by abnormal macropinocytosis of microvillar membranes. 4. Combined with OKA, SC-9 induced a transient reduction of rhabdoms, followed by overgrowth to abnormal sizes. Overgrowth was blocked by the transcription inhibitor actinomycin D. 5. Disparate consequences of combining OKA with SC-9 or PDA imply that more than one protein kinase C may be involved.
Blest
A D
AD
Centre for Visual Science and Developmental Neurobiology Group, Research School of Biological Sciences, Australian National University, Canberra ACT.
Stowe
S
S
Carter
M
M
Tsukitani
Y
Y
D000818:Animals; D003386:Brachyura / Q000502:physiology*; D004721:Endoplasmic Reticulum / Q000201:enzymology / Q000648:ultrastructure; D004789:Enzyme Activation; D004988:Ethers, Cyclic / Q000494:pharmacology; D008854:Microscopy, Electron; D019319:Okadaic Acid; D010703:Phorbol Esters / Q000494:pharmacology; D010744:Phosphoric Monoester Hydrolases / Q000037:antagonists & inhibitors; D010766:Phosphorylation; D010775:Photic Stimulation; D010786:Photoreceptor Cells / Q000187:drug effects / Q000502:physiology*; D010873:Pinocytosis / Q000187:drug effects; D011494:Protein Kinases / Q000378:metabolism*; D012160:Retina / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology*; D013449:Sulfonamides / Q000494:pharmacology
D004988:Ethers, Cyclic; D010703:Phorbol Esters; D013449:Sulfonamides; C049999:N-(6-phenylhexyl)-5-chloro-1-naphthalenesulfonamide; D019319:Okadaic Acid; D011494:Protein Kinases; D010744:Phosphoric Monoester Hydrolases