Lithium ions induce prestalk-associated gene expression and inhibit prespore gene expression in Dictyostelium discoideum.
We investigated the effect of Li+ on two types of cyclic AMP-regulated gene expression and on basal and cyclic AMP-stimulated inositol 1,4,5-triphosphate (Ins(1,4,5)P3) levels. Li+ effectively inhibits cyclic AMP-induced prespore gene expression, half-maximal inhibition occurring at about 2 mM-LiCl. In contrast, Li+ (1-3 mM) promotes the cyclic AMP-induced increase of cysteine proteinase-2 mRNA levels, and induces the expression of this prestalk-associated gene in the absence of cyclic AMP stimuli. At concentrations exceeding 4-5 mM, LiCl inhibits cysteine proteinase-2 gene expression. LiCl reduces basal Ins(1,4,5)P3 levels and decreases the cyclic AMP-induced accumulation of Ins(1,4,5)P3; both effects occur half-maximally at 2-3 mM-LiCl. These results indicate that the induction of the cysteine proteinase-2 gene by Li+ is not due to elevated levels of Ins(1,4,5)P3. It is, however, possible that inhibition of prespore gene expression by Li+ is caused by Li+-induced reduction of basal and/or stimulated Ins(1,4,5)P3 levels.
Peters
D J
DJ
Cell Biology and Genetics Unit, Leiden University, The Netherlands.
Van Lookeren Campagne
M M
MM
Van Haastert
P J
PJ
Spek
W
W
Schaap
P
P
D015105:3',5'-Cyclic-AMP Phosphodiesterases / Q000494:pharmacology; D002712:Chlorides / Q000494:pharmacology*; D000242:Cyclic AMP / Q000494:pharmacology*; D004023:Dictyostelium / Q000187:drug effects / Q000235:genetics* / Q000378:metabolism; D015870:Gene Expression / Q000187:drug effects*; D005800:Genes, Fungal / Q000187:drug effects*; D015544:Inositol 1,4,5-Trisphosphate / Q000378:metabolism*; D007700:Kinetics; D008094:Lithium / Q000494:pharmacology*; D018021:Lithium Chloride; D012333:RNA, Messenger / Q000235:genetics; D013172:Spores, Fungal / Q000502:physiology; D014158:Transcription, Genetic / Q000187:drug effects*
D002712:Chlorides; D012333:RNA, Messenger; D015544:Inositol 1,4,5-Trisphosphate; D008094:Lithium; D000242:Cyclic AMP; D015105:3',5'-Cyclic-AMP Phosphodiesterases; D018021:Lithium Chloride