PITUITARY HOMEOBOX-2, A NOVEL MEMBER OF THE BICOID-RELATED FAMILY OF HOMEOBOX GENES, IS A POTENTIAL REGULATOR OF ANTERIOR STRUCTURE FORMATION

Genetic analysis of mouse mutants has demonstrated the importance of t he homeobox genes Rpx, Lhx3 and Pit1 for anterior pituitary gland deve lopment, Pit1 mutations have also been identified in several human fam ilies with multiple pituitary hormone deficiencies, To identify additi onal homeobox regulators of pituitary development, we screened an adul t pituitary gland cDNA library for homeobox sequences, Here, we report the identification of a novel bicoid-related homeodomain gene express ing two alternatively spliced mRNA products, which encode proteins of 271 and 317 amino acids, respectively. The proteins have been named Pt x2a and Ptx2b since they are highly related to Ptx1/P-OTX. Ptx2 is exp ressed in both developing and adult pituitary gland, eye and brain tis sues, suggesting an important role in development and maintenance of a nterior structures, Ptx2 was mapped close to Egf on mouse chromosome 3 , in a region having extensive synteny homology with HSA 4q, These dat a make the human Ptx2 homologue a candidate gene for Rieger syndrome, an autosomal-dominant disorder with variable craniofacial, dental, eye and pituitary anomalies.