Involvement of Sp-1 in the regulation of the Id-1 gene during trophoblast cell differentiation.
Id-1, a member of the helix-loop-helix transcription factor family, inhibits the differentiation of Rcho-1 cells, which were derived from rat choriocarcinoma and consist of trophoblast stem cells. Id-1 is expressed at a high level in undifferentiated trophoblast stem cells and then down-regulated during early differentiation, and is thought to be a key regulator in the trophoblast giant-cell differentiation pathway. In this study, we analyzed the signaling mechanism regulating the high expression levels of Id-1 in undifferentiated Rcho-1 cells. Promoter deletion analysis revealed that a 31-bp sequence (Box-2 region), located between -200 and -169bp in the Id-1 promoter is necessary for the promoter activity. Electrophoretic mobility shift assays and DNA affinity precipitation assays showed that Box-2-binding activity was decreased during differentiation and that Sp-1 protein bound to this sequence. The protein level of Sp-1 was decreased during the differentiation. These results suggest that the Sp-1 protein level may regulate the Box-2-binding activity and the trophoblast giant-cell differentiation.
Takeda
T
T
Department of Obstetrics and Gynecology, Osaka University Graduate School of Medicine, 2-2 Yamadaoka, Suita, Osaka 565-0871, Japan. take@gyne.med.osaka-u.ac.jp
Sakata
M
M
Isobe
A
A
Yamamoto
T
T
Nishimoto
F
F
Minekawa
R
R
Hayashi
M
M
Okamoto
Y
Y
Desprez
P-Y
PY
Tasaka
K
K
Murata
Y
Y
D000818:Animals; D002454:Cell Differentiation / Q000502:physiology*; D002460:Cell Line; D004591:Electrophoresis, Polyacrylamide Gel; D024202:Electrophoretic Mobility Shift Assay; D005786:Gene Expression Regulation; D051798:Inhibitor of Differentiation Protein 1 / Q000235:genetics / Q000502:physiology*; D011401:Promoter Regions, Genetic; D051381:Rats; D015398:Signal Transduction / Q000502:physiology; D016329:Sp1 Transcription Factor / Q000502:physiology*; D014327:Trophoblasts / Q000166:cytology / Q000502:physiology*
C497454:ID1 protein, rat; D051798:Inhibitor of Differentiation Protein 1; D016329:Sp1 Transcription Factor