Pit-1/GH factor-1 involvement in the gene expression of somatolactin.
A presumed pituitary hormone, somatolactin (SL), belonging to the GH/PRL family, is produced in the intermediate lobe of teleost pituitary. The pituitary-specific transcription factor, Pit-1, is indispensable not only for the expression of mammalian GH and PRL genes, but for the development of GH- and PRL-producing cells present in the anterior lobe of the pituitary as well. Thus, in this study, examination was made of the possible involvement of Pit-1 in the intermediate lobe-specific expression of the SL gene. Using antibodies against chum salmon Pit-1, the presence of the 40-kilodalton Pit-1 protein in anterior and neurointermediate lobes of rainbow trout pituitary was demonstrated. By immunohistochemical examination, Pit-1 protein was shown to be located in the nuclei of SL-producing cells in the intermediate lobe. In experiments of cotransfection into HeLa cells, rat Pit-1 enhanced the promoter activity of SL gene, and a 0.5-kilobase upstream region from the transcriptional start site was sufficient for this enhancement. It follows from these results that Pit-1 protein may possibly be involved in SL gene expression as well as the development of SL-producing cells.
Ono
M
M
Department of Molecular Biology, School of Medicine, Kitasato University, Kanagawa, Japan.
Harigai
T
T
Kaneko
T
T
Sato
Y
Y
Ihara
S
S
Kawauchi
H
H
D000818:Animals; D015153:Blotting, Western; D004268:DNA-Binding Proteins / Q000032:analysis / Q000235:genetics / Q000502:physiology*; D029941:Fish Proteins; D015870:Gene Expression; D006023:Glycoproteins / Q000235:genetics*; D006367:HeLa Cells; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D017685:Oncorhynchus keta; D017686:Oncorhynchus mykiss / Q000378:metabolism*; D010902:Pituitary Gland / Q000378:metabolism*; D010903:Pituitary Gland, Anterior / Q000378:metabolism; D010907:Pituitary Hormones / Q000235:genetics*; D011401:Promoter Regions, Genetic; D051381:Rats; D017208:Rats, Wistar; D011993:Recombinant Fusion Proteins; D050817:Transcription Factor Pit-1; D014157:Transcription Factors / Q000032:analysis / Q000235:genetics / Q000502:physiology*; D014162:Transfection
D004268:DNA-Binding Proteins; D029941:Fish Proteins; D006023:Glycoproteins; C494187:POU1F1 protein, human; D010907:Pituitary Hormones; C494186:Pou1f1 protein, rat; D011993:Recombinant Fusion Proteins; D050817:Transcription Factor Pit-1; D014157:Transcription Factors; C064448:somatolactin protein, fish