Pit-1/growth hormone factor 1 splice variant expression in the rhesus monkey pituitary gland and the rhesus and human placenta.
We have examined the expression of Pit-1 messenger RNA (mRNA) splice variants in the nonhuman primate pituitary and in rhesus and human placenta. Full-length complementary DNAs (cDNAs) representing Pit-1 and the Pit-1 beta splice variants were cloned from a rhesus monkey pituitary cDNA library and were readily detectable by RT-PCR with rhesus pituitary gland RNA. The Pit-1T variant previously reported in mouse pituitary tumor cell lines was not detectable in normal rhesus pituitary tissue, although two novel splice variants were detected. A cDNA approximating the rat Pit-1 delta 4 variant was cloned but coded for a truncated and presumably nonfunctional protein. Only by using a nested RT-PCR approach were Pit-1 and Pit-1 beta variants consistently detectable in both human and rhesus placental tissue. The Pit-1 beta variant mRNA was not detectable in JEG-3 choriocarcinoma cells unless the cells were stimulated with 8-Br-cAMP. Immunoblot studies with nuclear extracts from primary rhesus syncytiotrophoblast cultures or JEG-3 choriocarcinoma cells indicated that although mRNA levels were very low, Pit-1 protein was detectable in differentiated cytotrophoblasts, and levels increased after treatment with 8-Br-cAMP. Two major species of Pit-1 protein were detected that corresponded to the two major bands in rat pituitary GH3 cell nuclear extracts. Low levels of slightly larger bands also were seen, which may represent Pit-1 beta protein or phosphorylated species. We conclude that Pit-1 splice variants expressed in the primate pituitary gland differ from those in the rodent gland and that the Pit-1 and Pit-1 beta mRNAs expressed in the placenta give rise to a pattern of protein expression similar to that seen in pituitary cells, which is inducible by treatment with 8-Br-cAMP.
Schanke
J T
JT
Department of Obstetrics and Gynecology, University of Wisconsin Medical School, Madison, USA.
Conwell
C M
CM
Durning
M
M
Fisher
J M
JM
Golos
T G
TG
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002417:Cattle; D004268:DNA-Binding Proteins / Q000235:genetics* / Q000378:metabolism*; D005260:Female; D006801:Humans; D008253:Macaca mulatta; D051379:Mice; D008969:Molecular Sequence Data; D010902:Pituitary Gland / Q000378:metabolism*; D010920:Placenta / Q000378:metabolism*; D016133:Polymerase Chain Reaction; D011247:Pregnancy; D012326:RNA Splicing; D012333:RNA, Messenger / Q000378:metabolism*; D051381:Rats; D050817:Transcription Factor Pit-1; D014157:Transcription Factors / Q000235:genetics* / Q000378:metabolism*; D014158:Transcription, Genetic
D004268:DNA-Binding Proteins; D012333:RNA, Messenger; D050817:Transcription Factor Pit-1; D014157:Transcription Factors; C494187:POU1F1 protein, human; C494185:Pou1f1 protein, mouse; C494186:Pou1f1 protein, rat