Distinct but overlapping expression patterns of two vertebrate slit homologs implies functional roles in CNS development and organogenesis

The Drosophila slit gene (sli) encodes a secreted leucine-rich repeat-conta ining protein (slit) expressed by the midline glial cells and required for normal neural development. A putative human sii homolog, SLIT1, has previou sly been identified by EST database scanning. We have isolated a second hum an sli homolog, SLIT2, and its murine homolog Slit2. Both SLIT1 and SLIT2 p roteins show approximately 40% amino acid identity to slit and 60% identity to each other. In mice, both genes are expressed during CNS development in the floor plate, roof plate and developing motor neurons. As floor plate r epresents the vertebrate equivalent to the midline glial cells, we predict a conservation of function for these vertebrate homologs. Each gene shows a dditional but distinct sites of expression outside the CNS suggesting a var iety of functions for these proteins. (C) 1998 Elsevier Science Ireland Ltd . All rights reserved.