Human growth hormone gene expression in rat but not human non-pituitary cells after stable gene transfer.
Tissue-specific expression of the rat growth hormone (rGH) gene requires binding of a pituitary-specific factor. Binding of this factor has been used to explain tissue-specific expression of the human growth hormone (hGH-N) gene in transfected rat pituitary (GC) tumour cells. Neither rat fibroblast (R2) nor human cervical carcinoma (HeLa) cells contain the rat pituitary-specific factor. Thus, no expression of hGH-N or rGH would be expected in these cells. R2 cell lines containing stably integrated hGH-N or rGH genes were generated. Expression of hGH-N but not rGH was detected. By contrast, stably transfected HeLa cells did not express the endogenous or transfected hGH-N genes. However, an hGH-N transcript was detected when hGH-N gene expression was directed by a viral promoter. This suggests that the block in expression occurs at the level of transcription and not mRNA stability. Hybrid genes containing 496 base pairs (bp) of hGH-N or 234 bp of rGH 5'-flanking DNA, including promoter sequences, fused to the bacterial gene coding for chloramphenicol acetyltransferase were used to stably transfect R2 cells. The hybrid hGH-N gene was more active than a promoterless construction in these cells. By contrast, the hybrid rGH gene was not. These data suggest that the hGH-N gene can be activated by rat transcription factors other than those found in pituitary cells.
Nickel
B E
BE
Department of Physiology, University of Manitoba, Winnipeg, Canada.
Nachtigal
M N
MN
Klassen
M E
ME
Cattini
P A
PA
D000818:Animals; D002460:Cell Line; D004247:DNA / Q000235:genetics; D015342:DNA Probes; D004274:DNA, Recombinant; D005347:Fibroblasts / Q000378:metabolism; D015870:Gene Expression; D013006:Growth Hormone / Q000235:genetics*; D006367:HeLa Cells / Q000378:metabolism; D006801:Humans; D009693:Nucleic Acid Hybridization; D010928:Placental Lactogen / Q000235:genetics; D011401:Promoter Regions, Genetic; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D014158:Transcription, Genetic; D014162:Transfection
D015342:DNA Probes; D004274:DNA, Recombinant; D012333:RNA, Messenger; D013006:Growth Hormone; D004247:DNA; D010928:Placental Lactogen