Localized expression of drm/gremlin in the central nervous system of the chicken embryo

Drm/Gremlin is a member of the Dan family of bone morphogenetic protein (BMP) antagonists known to function in vertebrate limb outgrowth and lung morphogenesis. Its expression detected in neurons and astrocytes of the adult brain suggested a possible role in brain morphogenesis and/or neuronal versus glial differentiation. To investigate this role, we analysed its expression pattern in the central nervous system of the chicken embryo, by in situ hybridization. In the brain, we found that drm is mainly expressed in the medial pallium in the dorsal telencephalon and in the ventral diencephalon. drm was detected in the meninges of the spinal cord. We also found that drm was expressed in the developing optic nerve and at the optic nerve/pecten junction. In all these territories, distinct bmps are expressed. Taken together, these data suggest that Drm could play a role in the development of the medial pallium and during optic nerve and pecten development by modulating BMP signaling.