Differential and coordinate responses of the human genes encoding the heat stable alkaline phosphatases to cAMP and sodium butyrate in the choriocarcinoma line JEG-3.
Human heat stable alkaline phosphatases are encoded by two closely related genes: the PLAP-1, which specifies the term placental enzyme, and the PLAP-2, which is expressed primarily in germ cells. In the choriocarcioma line JEG-3, 8-Br-cAMP induced the accumulation of the mRNA of both genes, while sodium butyrate induced the accumulation of PLAP-2 transcripts only. Each agent increased the transcription rate of one or both of the genes, as assayed by run-on transcription. In transfection of JEG-3 cells with PLAP promoters fused to the firefly luciferase gene, the activity of the PLAP-2 promoter (but not PLAP-1) was induced with sodium butyrate, while both promoters were induced by 8-Br-cAMP. Inducibility of the PLAP-2 promoter by 8-Br-cAMP was still observed when the promoter was shortened to -103, leaving intact a sequence resembling a cAMP response element. The extent of transcriptional activation by either agent was not sufficient to explain the accumulation of PLAP mRNA. These studies suggest that both transcriptional and posttranscriptional processes are involved in the induction of the PLAP-1 and PLAP-2 gene in JEG-3 cells.
Povinelli
C M
CM
Department of Pathology and Laboratory Medicine, Medical School, University of Texas Health Sciences Center, Houston.
Stewart
J M
JM
Knoll
B J
BJ
D015124:8-Bromo Cyclic Adenosine Monophosphate / Q000494:pharmacology*; D000469:Alkaline Phosphatase / Q000235:genetics*; D002087:Butyrates / Q000494:pharmacology*; D020148:Butyric Acid; D002822:Choriocarcinoma / Q000201:enzymology*; D004795:Enzyme Stability; D015870:Gene Expression / Q000187:drug effects*; D006358:Hot Temperature; D006801:Humans; D008156:Luciferases / Q000235:genetics; D009693:Nucleic Acid Hybridization; D011401:Promoter Regions, Genetic; D012333:RNA, Messenger / Q000096:biosynthesis; D014158:Transcription, Genetic / Q000187:drug effects; D014162:Transfection; D014407:Tumor Cells, Cultured
D002087:Butyrates; D012333:RNA, Messenger; D020148:Butyric Acid; D015124:8-Bromo Cyclic Adenosine Monophosphate; D008156:Luciferases; D000469:Alkaline Phosphatase