Identification, chromosomal assignment, and expression analysis of the human homeodomain-containing gene Orthopedia (OTP)

Homeodomain (HD) genes are helix-turn-helix transcription factors that play key roles in the specification of cell fates. In the central nervous syste m (CNS), HD genes not only position cells along an axis, but also specify c ell migration patterns and may influence axonal connectivity. In an effort to identify novel IID genes involved in the development of the human CNS, w e have cloned, characterized, and mapped the human homologue of the murine Ho gene Orthopedia (Otp), whose product is found in multiple cell groups wi thin the mouse hypothalamus, amygdala, and brain stem. Human cDNA and genom ic libraries were screened with probes derived from mouse Otp sequences to find the human homologue, OTP. The deduced amino acid sequence of the open reading frame of the human cDNA is 99% homologous to mouse Otp and demonstr ates a high degree of conservation when compared to sea urchin and Drosophi la. OTP was mapped to human chromosome 5q13.3 using radiation hybrid panel mapping and fluorescence in situ hybridization. Flanking markers were ident ified from YAC clones containing OTP. A single putative OTP gene product wa s found in 17-week human fetal brain tissue by Western blot analysis using a novel polyclonal antibody raised against a conserved 13-amino-acid sequen ce at the C-terminus of the OTP protein. Expression in the developing human hypothalamus was confirmed by immunohistochemistry. (C) 1999 Academic Pres s.