Differential binding of rat pituitary-specific nuclear factors to the 5'-flanking region of pituitary and placental members of the human growth hormone gene family.
Placental chorionic somatomammotropin (hCS-A or B) and growth hormone variant (hGH-V) are members of the human growth hormone family, and are related by structure and function to pituitary growth hormone (hGH-N). However, while the hGH-N gene is expressed specifically in the anterior pituitary, hGH-V and hCS are produced in the placenta. Hybrid hGH-N, hGH-V and hCS-A genes containing 5'-flanking sequences, including the endogenous promoter, are preferentially expressed in rat pituitary tumor (GC) cells, after gene transfer. Since interaction with a pituitary-specific protein (Pit 1) is required for efficient hGH-N as well as rat growth hormone (rGH) gene expression in GC cells, binding of pituitary proteins to the hGH-V and hCS-A promoter sequences was investigated. Rat Pit 1 binds at two locations on the hGH-N gene, a distal (-140/-107) and proximal site (-97/-66), in a similar manner to that observed with the rGH gene. By contrast, efficient Pit 1 binding was seen only to the distal site of the hGH-V gene and the proximal site of the hCS-A gene. Although binding of a protein to the distal hCS-A sequences was observed, the site of interaction was truncated (-140/-116), not pituitary-specific, and was more consistent with the binding of Sp1. These data indicate that rat Pit 1 binds to the placental hGH-V and hCS-A genes and correlates with their promoter activity in GC cells after gene transfer.(ABSTRACT TRUNCATED AT 250 WORDS)
Department of Physiology, University of Manitoba, Winnipeg, Canada.
B E
BE
Nickel
M W
MW
Nachtigal
M E
ME
Bock
P A
PA
Cattini
D000818:Animals; D001483:Base Sequence; D004268:DNA-Binding Proteins / Q000378:metabolism*; D003850:Deoxyribonuclease I / Q000378:metabolism; D005786:Gene Expression Regulation / Q000235:genetics*; D013006:Growth Hormone / Q000235:genetics* / Q000378:metabolism; D006367:HeLa Cells; D006801:Humans; D008969:Molecular Sequence Data; D009928:Organ Specificity; D010902:Pituitary Gland / Q000737:chemistry*; D010911:Pituitary Neoplasms / Q000235:genetics; D010928:Placental Lactogen / Q000235:genetics; D051381:Rats; D011993:Recombinant Fusion Proteins / Q000235:genetics; D012045:Regulatory Sequences, Nucleic Acid / Q000235:genetics*; D014158:Transcription, Genetic; D014407:Tumor Cells, Cultured
D004268:DNA-Binding Proteins; D011993:Recombinant Fusion Proteins; D013006:Growth Hormone; D010928:Placental Lactogen; D003850:Deoxyribonuclease I