Abstract

The pituitary gland is a complex endocrine organ secreting hormones that regulate a wide array of vertebrate physiological processes, including growth, lactation, metabolic homeostasis, reproduction, water balance, and the stress response. In the mature organ, specialized cells that have a common origin in the early ectoderm release their characteristic products into the bloodstream. Together, the embryological processes that commit the hormone-secreting cells to their specific fates and the clinical and agricultural relevance of understanding pituitary function have defined pituitary development as an excellent model system for the study of the genetic cascades that guide cell determination and differentiation. Recently, many genes that regulate pituitary development have been identified. These genes encode transcription factors and signaling proteins and often are expressed in temporally controlled, pituitary-specific or pituitary-restricted patterns. Further, dominant and recessive mutations in these genes are associated with compound pituitary diseases in human patients and animal models. The advance of genome projects will facilitate approaches to understand the genetic mechanisms that regulate the activation of pituitary regulatory genes and to discover how the function of the encoded transcription factors is precisely regulated by intrinsic and extrapituitary signals. Gene array and differential screening approaches will enable the identification of direct and downstream target genes of pituitary transcription factors. Protein interaction screens will identify regulatory proteins required for pituitary gene control. Characterization of the pathways that coordinate pituitary development will direct treatment of pediatric and adult pituitary diseases, guide genetic counseling of families with hereditary conditions affecting the pituitary, and may allow embryonic manipulation to improve productivity in the meat industry.