P-OTX - A PIT-1-INTERACTING HOMEODOMAIN FACTOR EXPRESSED DURING ANTERIOR-PITUITARY GLAND DEVELOPMENT

A novel OTX-related homeodomain transcription factor has been identifi ed on the basis of its ability to interact with the transactivation do main of the pituitary-specific POU domain protein, Pit-1, This factor, referred to as P-OTX (pituitary OTX-retated factor), is expressed in primordial Rathke's pouch, oral epithelium, first branchial arch, duod enum, and hindlimb. In the developing anterior pituitary, it is expres sed in all regions from which cells with distinct phenotypes will emer ge in the mature gland. P-OTX is able to independently activate and to synergize with Pit-1 on pituitary-specific target gene promoters, The refore, P-OTX may subserve functions in generating both precursor and specific cell phenotypes in the anterior pituitary gland and in severa l other organs.