Molecular Endocrinology, Vol 8, 109-115, Copyright © 1994 by Endocrine Society

ARTICLES

Pit-1/GH factor-1 involvement in the gene expression of somatolactin

M Ono, T Harigai, T Kaneko, Y Sato, S Ihara and H Kawauchi
Department of Molecular Biology, School of Medicine, Kitasato University, Kanagawa, Japan.

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.

This article has been cited by other articles:

				B.-Y. Yang and T. T. Chen Identification of a New Growth Hormone Family Protein, Somatolactin-Like Protein, in the Rainbow Trout (Oncorhyncus mykiss) Pituitary Gland Endocrinology, March 1, 2003; 144(3): 850 - 857. [Abstract] [Full Text] [PDF]