Control of the anterior pituitary cell lineage regulator POU1F1 by the stem cell determinant Musashi

The cytokine leptin regulates energy homeostasis through ubiquitously expressed leptin receptors.  Leptin has a number of major signaling targets in the brain, including cells of the anterior pituitary (AP).  We have previously reported that mice lacking leptin receptors in AP somatotropes display growth hormone (GH) deficiency, metabolic dysfunction and adult onset obesity.  Amongst other targets, leptin signaling promotes increased levels of the pituitary transcription factor POU1F1 (also referred to as Pit1) which, in turn, regulates the specification of somatotrope, lactotrope and thyrotrope cell lineages within the anterior pituitary.  Leptin’s mechanism of action on somatotropes is sex-dependent, with females demonstrating post-transcriptional control of Pou1f1 mRNA translation.  In this study, we have investigated the mechanism that regulates Pou1f1 mRNA translational control and report that the stem cell marker and mRNA translational control protein, Musashi1, exerts repression ...