Adgrg1 is a New Transcriptional Target of Hand1 During Trophoblast Giant Cell Differentiation

The placenta, forming the maternal–fetal interface, is essential for the survival and development of the fetus. It has been shown that the basic helix-loop-helix (bHLH) transcription factor Hand1 plays an important role in trophoblast giant cells (TGCs) differentiation during placental development in mice. However, the underlying molecular mechanism remains elusive. We hereby report that Adgrg1 (GPR56), a G protein coupled receptor, was a new transcriptional target of Hand1. Hand1 activated the expression of Adgrg1 by binding to its promoter region during TGCs differentiation. Double in situ hybridization revealed co-expression of Hand1 and Adgrg1 in TGCs, and Adgrg1 was located to Prl2c2+ TGCs in the junctional zone of the placenta. Knockdown of Adgrg1 not only led to increased expression of Prl2c2, but also the improvement of cell migration during TGC differentiation. Moreover, the ligands of Adgrg1, Tgm2 and Col3a1, were expressed in Prl2c2+ TGCs located in the placental junctional zone and maternal spiral arteries, respectively, further providing preconditions for the function of Adgrg1 in TGCs. Collectively, these results demonstrate that Adgrg1 is a new transcriptional target of Hand1, affecting Prl2c2 expression and cell migration during TGCs differentiation. Tgm2 and Col3a1 may be involved in TGC differentiation regulated by Adgrg1 in the manners of autocrine or paracrine. As a transmembrane receptor, Adgrg1 perhaps could act as a potential therapeutic target for placental-associated diseases caused by abnormal trophoblast migration, providing new insights for the preventions and therapies of placenta-related diseases. Overall design: RNA from trophoblast cells with or without 0.6 ug/ml dox under the differentiation condition for 2 days were prepared using Illumina RNA-Seq Preparation Kit and subjected sequencing with a BGISEQ-500 sequencer (China, BGI). RNA-seq raw data were initially filtered to obtain clean data after quality control. Clean data were aligned to the mouse genome (mm10) by HISAT2. Raw counts for each gene were calculated by EdgeR.