Mediation of growth hormone-dependent transcriptional activation by mammary gland factor/Stat 5.
Previous observations have shown that binding of growth hormone to its receptor leads to activation of transcription factors via a mechanism involving phosphorylation on tyrosine residues. In order to establish whether the prolactin-activated transcription factor Stat 5 (mammary gland factor) is also activated by growth hormone, nuclear extracts were prepared from COS-7 cells transiently expressing transfected Stat 5 and growth hormone receptor cDNA. Gel electrophoresis mobility shift analyses revealed the growth hormone-dependent presence of specific DNA-binding proteins in these extracts. The complexes formed could be supershifted by polyclonal anti-Stat 5 antiserum. In other experiments nuclear extracts from growth hormone-treated Chinese hamster ovary cells stably expressing transfected growth hormone receptor cDNA and liver from growth hormone-treated hypophysectomized rats were used for gel electrophoresis mobility shift analyses. These also revealed the presence of specific DNA-binding proteins sharing antigenic determinants with Stat 5. Stat 5 cDNA was shown to be capable of complementing the growth hormone-dependent activation of transcription of a reporter gene in the otherwise unresponsive COS-7 cell line. This complementation was dependent on the presence of Stat 5 tyrosine 694, suggesting a role for phosphorylation of this residue in growth hormone-dependent activation of DNA-binding and transcription.
Wood
T J
TJ
Department of Medical Nutrition, Karolinska Institute, Novum, Huddinge, Sweden.
Sliva
D
D
Lobie
P E
PE
Pircher
T J
TJ
Gouilleux
F
F
Wakao
H
H
Gustafsson
J A
JA
Groner
B
B
Norstedt
G
G
Haldosén
L A
LA
D000818:Animals; D001483:Base Sequence; D016466:CHO Cells; D006224:Cricetinae; D004268:DNA-Binding Proteins / Q000502:physiology*; D013006:Growth Hormone / Q000494:pharmacology*; D008894:Milk Proteins; D008969:Molecular Sequence Data; D011388:Prolactin / Q000494:pharmacology; D050799:STAT5 Transcription Factor; D015534:Trans-Activators / Q000502:physiology*; D015533:Transcriptional Activation / Q000187:drug effects*
D004268:DNA-Binding Proteins; D008894:Milk Proteins; D050799:STAT5 Transcription Factor; D015534:Trans-Activators; D011388:Prolactin; D013006:Growth Hormone