Qian Xi, Zhao Feng-Qi
Laboratory of Lactation and Metabolic Physiology, Department of Animal Science, University of Vermont, Burlington, VT 05405, USA.
Laboratory of Lactation and Metabolic Physiology, Department of Animal Science, University of Vermont, Burlington, VT 05405, USA.
Gen Comp Endocrinol. 2014 Aug 1;204:185-94. doi: 10.1016/j.ygcen.2014.05.021. Epub 2014 May 23.
Octamer-binding transcription factor-1 (Oct-1) is found to mediate lactogenic hormones (prolactin and glucocorticoids, HP)-induced β-casein gene expression in mammary alveolar secretory epithelial cells (MECs). The mammary gland also expresses Oct-2 isoform. In this study, we show that Oct-2 is also involved in HP-induced β-casein expression. Oct-2 endogenously binds to the β-casein promoter in MECs, and HP induce Oct-2 binding activity via mechanisms other than increasing Oct-2 expression or inducing Oct-2 translocation to the nucleus. Oct-2 transactivates HP-induced β-casein gene expression and this function is exchangeable with Oct-1. In MECs, Oct-2 is found to physically interact with Oct-1 regardless of HP treatment. However, HP induce physical interactions of Oct-2 with both signal transducer and activator of transcription 5 (STAT5) and glucocorticoid receptor (GR). These results provided biochemical evidence that Oct-2 may form a heteromer with Oct-1 in induction of β-casein gene expression by HP in MECs.
八聚体结合转录因子1（Oct-1）被发现可介导泌乳激素（催乳素和糖皮质激素，HP）诱导的乳腺腺泡分泌上皮细胞（MECs）中β-酪蛋白基因的表达。乳腺也表达Oct-2异构体。在本研究中，我们表明Oct-2也参与HP诱导的β-酪蛋白表达。Oct-2在MECs中内源性结合β-酪蛋白启动子，并且HP通过增加Oct-2表达或诱导Oct-2易位至细胞核以外的机制诱导Oct-2结合活性。Oct-2反式激活HP诱导的β-酪蛋白基因表达，并且该功能可与Oct-1互换。在MECs中，无论是否进行HP处理，均发现Oct-2与Oct-1存在物理相互作用。然而，HP诱导Oct-2与信号转导子和转录激活子5（STAT5）以及糖皮质激素受体（GR）发生物理相互作用。这些结果提供了生化证据，表明在MECs中HP诱导β-酪蛋白基因表达的过程中，Oct-2可能与Oct-1形成异源二聚体。
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