Figure 6. Model of hGH-Induced Phenotypic Changes in Pdx1-CreLate.
β Cells
Pdx1-promoter-driven expression of the hGH minigene causes biosynthesis and secretion of hGH, which exerts autocrine or paracrine effects after binding to PRLR on β cells. This causes STAT5 phosphorylation and pregnancy-like phenotypic changes, such as enhanced β cell mass and serotonin (5-HT) production. In addition, expression of the hGH minigene causes pregnancy-unrelated changes, such as reduction of GLUT2 expression and partial loss of glucose-induced insulin release. Lower GLUT2-mediated uptake and higher β cell mass protect against the diabetogenic effect of the β cell toxin STZ.