The role of glial cells missing 2 in induced pluripotent stem cell parathyroid differentiation

Glial cells missing 2 (GCM2) has been identified as an essential factor for parathyroid differentiation, and GCM2 silencing in parathyroid cells decreases calcium-sensing receptor (CaSR) expression. However, the role of GCM2 in parathyroid differentiation from induced pluripotent stem cells (iPSCs) is unclear. Here, we investigated the role of GCM2 in parathyroid differentiation from iPSCs using the Tet-On 3 G system. We confirmed that iPS cells transfected with GCM2/TRE3G and pCMV-Tet3G vectors express GCM2 in a doxycycline-dependent manner. Though parathyroid glands derive from the endoderm and differentiate via the third pharyngeal arch (PPE), overexpression of GCM2 in iPSCs significantly abolished the suppression of OCT4 and SOX2, suggesting inhibition of endodermal differentiation. GCM2 overexpression at the stage of differentiation into the third PPE also increased the expression levels of CaSR and parathyroid hormone, and increased the number of CaSR⁺/EpCAM⁺ cells. These results suggest that GCM2 regulates parathyroid differentiation after endoderm differentiation rather than at an earlier stage.