TY - JOUR
T1 - Activation of cAMP-dependent protein kinase increases the protein level of steroidogenic factor-1
AU - ÆSøY, Reidun
AU - Mellgren, Gunnar
AU - Morohashi, Ken Ichirou
AU - Lund, Johan
PY - 2002/1/22
Y1 - 2002/1/22
N2 - The orphan nuclear receptor steroidogenic factor 1 (SF-1) is an essential regulator of endocrine organogenesis, sexual differentiation, and steroidogenisis. SF-1 is a transcriptional regulator of cAMP responsive genes, but the exact mechanisms by which cAMP-dependent PKA modulates SF-1 dependent transcription leading to increased steroidogenic output have not been determined. In this report the effects of PKA activation on SF-1 in living cells have been examined by the use of full-length SF-1 cDNA fused to the cDNA encoding green fluorescent protein (GFP). The GFP-SF-1 fusion protein localized to the nucleus of both steroidogenic Y1 cells and non-steroidogenic COS-1 cells, and the functional properties of wild-type SF-1 were conserved. When the catalytic subunit of PKA was coexpressed with GFP-SF-1, we observed that the fluorescence emission was markedly elevated. These findings were confirmed by Western blot analysis, showing that stimulation of PKA increased SF-1 protein levels. The PKA-induced expression of SF-1 protein was not accompanied by an increase in SF-1 mRNA levels. However, pulse-chase studies showed a decrease in SF-1 degradation rate in response to activation of PKA, indicating that PKA elevates the level of SF-1 by increasing the stability of SF-1 protein.
AB - The orphan nuclear receptor steroidogenic factor 1 (SF-1) is an essential regulator of endocrine organogenesis, sexual differentiation, and steroidogenisis. SF-1 is a transcriptional regulator of cAMP responsive genes, but the exact mechanisms by which cAMP-dependent PKA modulates SF-1 dependent transcription leading to increased steroidogenic output have not been determined. In this report the effects of PKA activation on SF-1 in living cells have been examined by the use of full-length SF-1 cDNA fused to the cDNA encoding green fluorescent protein (GFP). The GFP-SF-1 fusion protein localized to the nucleus of both steroidogenic Y1 cells and non-steroidogenic COS-1 cells, and the functional properties of wild-type SF-1 were conserved. When the catalytic subunit of PKA was coexpressed with GFP-SF-1, we observed that the fluorescence emission was markedly elevated. These findings were confirmed by Western blot analysis, showing that stimulation of PKA increased SF-1 protein levels. The PKA-induced expression of SF-1 protein was not accompanied by an increase in SF-1 mRNA levels. However, pulse-chase studies showed a decrease in SF-1 degradation rate in response to activation of PKA, indicating that PKA elevates the level of SF-1 by increasing the stability of SF-1 protein.
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U2 - 10.1210/en.143.1.295
DO - 10.1210/en.143.1.295
M3 - Article
C2 - 11751621
AN - SCOPUS:0000638563
VL - 143
SP - 295
EP - 303
JO - Endocrinology
JF - Endocrinology
SN - 0013-7227
IS - 1
ER -