title: Transcription factors in normal and neoplastic pituitary tissues.
abstract: Transcription factors are proteins that bind to regulatory elements in DNA and have critical roles in gene regulation during development, in cellular growth and differentiation. The four major groups of transcription factors have been classified according to the motif in the DNA-binding domains and include: (1) the helix-turn-helix group, which includes the Pit-1/GHF-1 (Pit-1) transcription factor; (2) the zing finger group, which includes estrogen and other steroid hormone receptors; (3) the leucine zipper group, which includes c-fos protooncogene, and (4) the helix-loop-helix group, which includes the c-myc oncogene. Members of all four groups have been described in normal and neoplastic anterior pituitary gland tissues. Pit-1 has been shown to regulate prolactin (PRL), growth hormone (GH), and thyroid-stimulating hormone (TSH) cells during development and differentiation. Genetic defects in this transcription factor have led to specific diseases in rodents and humans such as dwarfism and cretinism. Estrogen receptor (ER) protein plays a critical role in the regulation of gene expression in some anterior pituitary cells. There is a differential distribution of ER in anterior pituitary cells and tumors; PRL, gonadotroph, and null cell tumors are the principal adenomas expressing ER. The protooncogene c-fos is regulated by estrogen in various tissues, linking the regulation of one transcription factor by another transcription factor with a different motif. The c-myc oncogene has been detected in the pituitary gland and in some pituitary tumors, although the exact role of this oncogene in pituitary tumor development is uncertain. Because of the critical role that transcription factors play in pituitary cell development and differentiation, we can anticipate many more studies to elucidate their many functions in normal and neoplastic pituitary tissues.
authors.affiliation: Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, Minnesota 55905, USA.
authors.forename: R V
authors.initials: RV
authors.lastname: Lloyd
authors.forename: R Y
authors.initials: RY
authors.lastname: Osamura
mesh_terms: D000818:Animals; D000242:Cyclic AMP / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000378:metabolism; D005260:Female; D005786:Gene Expression Regulation; D006801:Humans; D007150:Immunohistochemistry; D017403:In Situ Hybridization; D008297:Male; D051379:Mice; D008822:Mice, Transgenic; D010902:Pituitary Gland / Q000378:metabolism* / Q000648:ultrastructure; D010911:Pituitary Neoplasms / Q000378:metabolism* / Q000648:ultrastructure; D016760:Proto-Oncogene Proteins c-fos / Q000378:metabolism; D016271:Proto-Oncogene Proteins c-myc / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D011960:Receptors, Estrogen / Q000378:metabolism; D050817:Transcription Factor Pit-1; D014157:Transcription Factors / Q000378:metabolism*
chemical_list: D000242:Cyclic AMP; D004268:DNA-Binding Proteins; D016760:Proto-Oncogene Proteins c-fos; D016271:Proto-Oncogene Proteins c-myc; D012333:RNA, Messenger; D011960:Receptors, Estrogen; D050817:Transcription Factor Pit-1; D014157:Transcription Factors; C494187:POU1F1 protein, human; C494185:Pou1f1 protein, mouse