Vasopressin and Oxytocin: Molecular Biology and Evolution of the Peptide Hormones and Their Receptors

Abstract

This chapter describes the vasopressin (VP) and oxytocin (OT) gene expression and regulation. The nonapeptides VP and OT, the major secretory products of magnocellular neurons of the hypothalamo–neurohypophysial system, are synthesized as parts of larger precursor proteins in different subsets of hypothalamic cells. They consist of a hydrophobic signal peptide at their N-terminal ends and the hormone moiety followed by the sequence Gly-Lys-Arg, the signal for hormone modification and precursor processing, respectively. Their major part is contributed by the carrier proteins, the neurophysins. The VP precursor only contains an additional component, the glycopeptide (GP). In a human small-cell lung carcinoma cell line with endogenous VP gene expression, glucocorticoid administration results in elevated rather than diminished VP messenger RNA (mRNA) levels. The effect was seen only upon costimulation with analogs of cAMP, pointing toward an interaction of different transcription factors. The somatic recombination between the VP and OT genes in hypothalamic neuron are also elaborated in the chapter.