Positive contribution of the IRE1α–XBP1 pathway to placental expression of CEA family genes

Inositol requiring enzyme-1α (IRE1α) is an ER-located transmembrane RNase whose activation leads to the production of the transcription factor X-box binding protein 1 (XBP1). Recently, we showed that the IRE1α–XBP1 pathway plays an essential role in the placenta. However, details of its function remain unclear. To address this point, we searched for IRE1α- or XBP1-regulated genes in the placenta, and identified the CEA family as a novel target of the IRE1α–XBP1 pathway. Moreover, PSG genes, which also belong to the CEA family, were up-regulated by XBP1. We have therefore identified a new aspect of the physiological function of the IRE1α–XBP1 pathway in the placenta.