Abstract
Alkaline phosphatase (ALP) in human choriocarcinoma cells (malignant trophoblasts) was characterized by its greater sensitivity to EDTA and L-leucine inhibition as compared with the placental isozyme. In addition, both the fully processed and the nonglycosylated forms of choriocarcinoma ALP migrated faster than the corresponding placental enzyme in sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Choriocarcinoma cells express a 2.6-kilobase (kb) ALP mRNA unlike normal human placenta which expresses a 2.8-kb ALP mRNA. Administration of sodium butyrate to choriocarcinoma cells greatly increased the steady-state levels of the 2.6-kb choriocarcinoma ALP mRNA, which resulted in an increase in enzyme activity and biosynthesis. S1 nuclease analysis using probes derived from a placental ALP cDNA and ribonuclease protection assays employing probes derived from the germ cell ALP gene demonstrated that choriocarcinoma cells express the germ cell ALP gene. The germ cell ALP gene encodes the placental ALP-like isozyme that is primarily expressed in the thymus, testis, and germ cell tumors. The structures of the internal exons (II-X) of the germ cell ALP gene were determined previously based on their similarity to the placental ALP gene. However, the boundaries of exons I and XI (3' exon) of the germ cell ALP gene were not defined due to sequence divergence between the two genes at the 5' and 3' regions. Ribonuclease protection and primer extension assays demonstrated that exon I of this gene is 119 base pairs in length and that germ cell ALP mRNA contains one major transcription initiation site. The isolation and characterization of germ cell ALP cDNA clones from a butyrate-treated choriocarcinoma cDNA library showed that the germ cell ALP mRNA is 2487 bases in length and exon XI of this gene is 1135 base pairs long.
Highlights
Alkaline phosphatase (ALP) in human choriocarci- chemical analyses [1,2,3]
S I Nuclease Analysis-Uniformly labeled single-stranded fragments generated by primer extension of a near full length placental ALP cDNA TPAP51A were used to analyze riocarcinoma is a typeof germ cell tumor which is of extraem- choriocarcinoma ALP mRNA
Induction of Placental Alkaline Phosphatase Synthesis by Sodium Butyrate-Since the placental ALP-like isozyme in choriocarcinoma cells appears tobe preferentially induced by butyrate, we examined the effects of butyrate on placental ALP gene expression in primary placental cultures that express mainly the placental ALP mRNA
Summary
Vol 264, No 21, Issue of July 25, pp. 12611-12619, 1989 Printed in U.S.A. Expression of the Germ Cell Alkaline PhosphataseGene in Human Choriocarcinoma Cells*. The placental ALP-ligkeerm cell isozyme is characterized by its sensitivity to EDTA and L-leucine inhibition [15,16,17], suggesting that choriocarcinoma cell lines may express the germ cell ALP gene. S I Nuclease Analysis-Uniformly labeled single-stranded fragments generated by primer extension of a near full length placental ALP cDNA TPAP51A (in anM13mp vector) were used to analyze riocarcinoma is a typeof germ cell tumor which is of extraem- choriocarcinoma ALP mRNA. Ribonuclease protection assays provided evidence that human choriocarcinomacells express thegerm cell ALP gene This wasconfirmed by theisolationand characterization of cDNA clones encoding thegerm cell ALP from a butyrate-treated choriocarcinomacDNA library. The hybrids were digested with S1 nuclease (900 units, Boehringer Mannheim)
Sign-in/Register to view highlights & summary 
Published Version
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call