SICB Division of Comparative Endocrinology (DCE)

DCE Researchers Database Entry

Stacia Sower

Molecular Evolution of the Neuroendocrine System
The research in my laboratory and with my collaborators and students emphasizes multidisciplinary approaches to studying the molecular and evolution of the neuroendocrine system in basal vertebrates. As an agnathan, the sea lamprey has become a model system for analysis of several systems including the evolution of the neuroendocrine regulation of reproduction. Lampreys were identified in a pivotal position such that the mapping of the lamprey genome started in Jan 2005. For neuroendocrine studies the availability of the genome offers incredible opportunities for identification of ligands, receptors, transcription factors and signaling pathways. Our ongoing studies focus on the molecular, biochemical and functional studies of gonadotropin releasing hormone and glycoproteins such as gonadotroprin and respective receptors in lamprey to test the overall hypothesis that lamprey hormones and their receptor(s) share common functional and developmental features compared to later evolved vertebrates. The hypothalamic-pituitary (HP) system is considered to be a vertebrate innovation and seminal event that emerged prior to or during the differentiation of the ancestral Agnathans. In spite of the very diverse patterns of life cycles and reproductive strategies and behaviors, this endocrine system is remarkably conserved throughout the Gnathostome lineages. We propose a modified paradigm in that the neuroendocrine control of reproduction and thyroid functions in the Agnathan sea lamprey exhibits an overlapping, simplified organization represented by one glycoprotein hormone putatively interacting with two receptors (see diagram above). Our working hypothesis is that the glycoprotein hormone/glycoprotein hormone receptor systems emerged as a link between the neuroendocrine and peripheral control levels during the early stages of Gnathostome divergence.