Development of a pituitary-specific cre line targeted to the Pit-1 lineage

Tissue-specific expression of the Cre recombinase is a well-established genetic tool to analyze gene function in specific tissues and cell types. In this report, we describe the generation of a new transgenic line that expresses Cre under the control of the rat growth hormone releasing hormone receptor (rGhrhr) promoter. This promoter, chosen to target the anterior pituitary, drives cre-mediated recombination in cells of the Pit1 lineage, including somatotrophs, lactotrophs, and thyro-trophs. Cre activity is first detected at embryonic day 13.5, and gradually increases to reach high level expression by postnatal day 2. In addition to the pituitary, rGhrhr-cre expression was detected in vibrissae and in hair follicles of the proximal limb, but not in other tissues. The rGhrhr-cre line will be a valuable tool for the study of the development of the pituitary Pit1 lineage and for the study of tumorigenesis involving these cells.