How is placental specific transcription factor GCMa/1 involved in development and maintanance of placenta?

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The glial cell-missing (GCM) gene is the primary regulator of glial cell determination in the nervous system of Drosophila melanogaster. Two mammalian homologues have been identified. One of them, GCMa/1 is a transcription factor that solely expresses in the placenta. It is required for the development of syncytiotrophoblast that forms branching morphology of the placenta. Null-mutation of the factor results early embryonic death due to the placental failure.We tried to get mouse monoclonal antibodies against hGCMa/1. We obtained 2 clones that detected hGCMa/1 expressed in E coli and in insect cells. Authentic hGCMa/1 in normal term placenta and mGCMa/1 in mouse placenta were also recognized by the antibodies in Western blotting.We cloned a GCM ortholog from chicken. The new GCM ortholog (chGCM) is expressed only transiently during embryogenesis and is restricted exclusively to extra-embryonic tissue. To further compare the expression of chGCM to other GCM protein, we analyzed a set of organs from adult chicken. We failed to detected chGCM in thymus, which is the tissue known to expressed mouse GCMa postnatally. Intriguingly, chGCM was detected in adult ovaries, confirmed by Northern blotting. Taking the extraembryonic expression of chGCM and mammalian GCMa, it is tempting to speculate that a conserved extra-embryonic function exits for GCM protein in birds and mammals.We tried the expression of GCMa/1 gene in placenta of different gestational age as determined by quantitative real-time RT-PCR. GCMa/1 mRNA was constantly detected throughout the analyzed stages with slight decreases during the late third trimester.