Pit-1 gene expression in the human pituitary and pituitary adenomas.
The cellular basis for pituitary neoplasia is poorly understood. The POU domain protein Pit-1 is a pituitary-specific transcription factor involved in the generation, differentiation, and proliferation of three pituitary cell types: lactotrophs, somatotrophs, and thyrotrophs. In this study, we analyzed the expression of Pit-1 gene in a series of 15 different human pituitary tumors and compared it with that observed in normal tissue. Pit-1 transcripts, identical in size (2.4 and 4.5 kilobases) and sequence to those observed in normal tissue were evidenced in PRL-, GH-, and TSH-secreting tumors. Pit-1 is overexpressed (2.5- to 5-fold) in the PRL- and GH-secreting tumors, but to an extent consistent with the predominant cellular type of these adenomas. An isoform of Pit-1, with an insertion of 26 amino acids in the trans-activation domain as a result of alternative splicing, is also present in both normal and tumoral tissues. It is concluded that human pituitary tumorigenesis does not seem to be associated with a gross alteration of Pit-1 gene expression.
INSERM U297, Marseille, France.
I
I
Pellegrini
A
A
Barlier
G
G
Gunz
D
D
Figarella-Branger
A
A
Enjalbert
F
F
Grisoli
P
P
Jaquet
D000236:Adenoma / Q000378:metabolism*; D000293:Adolescent; D000328:Adult; D000368:Aged; D017398:Alternative Splicing; D000595:Amino Acid Sequence; D001483:Base Sequence; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000737:chemistry / Q000235:genetics; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000235:genetics*; D005260:Female; D015870:Gene Expression; D013006:Growth Hormone / Q000378:metabolism; D006801:Humans; D008297:Male; D008875:Middle Aged; D008969:Molecular Sequence Data; D010902:Pituitary Gland / Q000378:metabolism*; D010911:Pituitary Neoplasms / Q000378:metabolism*; D016133:Polymerase Chain Reaction; D011388:Prolactin / Q000378:metabolism; D013972:Thyrotropin / Q000378:metabolism; D050817:Transcription Factor Pit-1; D014157:Transcription Factors / Q000737:chemistry / Q000235:genetics*
D018076:DNA, Complementary; D004268:DNA-Binding Proteins; C494187:POU1F1 protein, human; D050817:Transcription Factor Pit-1; D014157:Transcription Factors; D011388:Prolactin; D013972:Thyrotropin; D013006:Growth Hormone