Ascorbic Acid Uptaken by Sodium-Dependent Vitamin C Transporter 2 Induces beta hCG Expression through Sp1 and TFAP2A Transcription Factors in Human Choriocarcinoma Cells

作者：Chen, Lihua; Zhu, Haibin; Pan, Yibin; Tang, Chao; Watanabe, Mai; Ruan, Hongfeng; Wang, Yongjie; Wang, Jirong; Yao, Hong-Yi; Iguchi, Takuma; Wu, Ximei^*

来源：Journal of Clinical Endocrinology & Metabolism, 2012, 97(9): E1667-E1676.

DOI：10.1210/jc.2012-1753

• HUMAN CHORIONIC-GONADOTROPIN
• BOVINE GRANULOSA-CELLS
• PLACENTAL FUNCTION
• OXIDATIVE STRESS
• TROPHOBLAST
• SUPPLEMENTATION
• PROGESTERONE
• SECRETION
• DIFFERENTIATION
• PREGNANCY

Context: Vitamin C [ascorbic acid (AA)] is transported by sodium-dependent vitamin C transporters (SVCT) 1 and 2, and our previous studies show AA induces a dramatic production of steroid hormones in human choriocarcinoma cells. However, whether AA induces the production of placental polypeptide hormones remains unknown. Here we investigated the mechanisms governing AA induced beta-human chorionic gonadotropin (hCG) expression.
Methods: Frozen sections from human term placentas were used for immunostaining of SVCT, and beta hCG mRNA expression and its production in primary human placental cytotrophoblasts and JEG-3 cells were examined by quantitative RT-PCR and ELISA, respectively. Knockdown of SVCT2, transcription factor activating enhancer-binding protein 2 alpha (TFAP2A), or specificity protein-1 (Sp1) expression was achieved by retrovirus-mediated short hairpin RNA, and the transcriptional factors responsible for AA-induced beta hCG expression was identified by reporter constructs.
Results: Both SVCT1 and SVCT2 are expressed in human term placentas. SVCT2 is predominantly localized in the syncytial layer, whereas SVCT1 is predominantly distributed in the villous core. AA dramatically induces beta hCG mRNA expression and its production in JEG-3 cells and primary human cytotrophoblasts, and knockdown of SVCT2 expression in JEG-3 cells significantly decreases AA-induced beta hCG expression. Data from beta hCG5 construct and its deletion mutants further indicate that AA induces beta hCG5 transactivation through Sp1 and TFAP2A transcriptional factors, and silence of Sp1 and/or TFAP2A expression significantly decreased AA-induced beta hCG5 reporter activity and beta hCG expression as well.
Conclusions: The present study revealed the novel effects of AA on polypeptide hormone, beta hCG, production and the potential mechanisms governing AA-induced beta hCG expression, suggesting the potentially indispensable roles of AA in placental endocrine and pregnant maintenance. (J Clin Endocrinol Metab 97: E1667-E1676, 2012)

• 出版日期2012-9
• 单位浙江大学