Expression ofMeis2, aKnotted-related murine homeobox gene, indicates a role in the differentiation of the forebrain and the somitic mesoderm

Knotted (Kn) genes are expressed within restricted domains of the plant meristems and play a key role in the control of plant morphogenesis. We have isolated the Kn-related gene Meis2 in mouse, which labels the lateral somitic compartment and its derivatives during early mouse embryogenesis and later becomes a marker for the dorso-ectodermal region overlying cells of the paraxial mesoderm. Meis2 is also highly expressed in specific areas of the developing central nervous system from embryonic day 9 (e9) onward. In later developmental stages, a strong expression is detectable in differentiating nuclei and regions of the forebrain, midbrain, hindbrain, and spinal cord. This temporal and spatial expression pattern suggests that Meis2 may play an important role in the cascade of induction leading to somitic differentiation as well as in brain regionalization and histogenesis.