Evolution of vertebrate neuronal and endocrine gene families

Our studies of several neuronal and endocrine gene families have shown that many of these have quadrupled in the two ancient vertebrate tetraploidizations. These extensive duplications have expanded and elaborated, for instance, the opioid system involved in pain and reward mechanisms. The evolution of the NPY system in vertebrates is even more complicated and our results after several years of studies have demonstrated that most of the complexity of the NPY system arose very early in vertebrate evolution, prior to the origin of jawed vertebrates, with a first local triplication and subsequent chromosome duplications resulting in no less than seven NPY receptors in the vertebrate ancestor. Unexpectedly, mammals turn out to have lost 2-3 of these, whereas other lineages such as cartilagenous fishes (sharks and rays) the coelacanth Latimeria chalumnae, have retained all seven. Teleost fishes have acquired duplicates of both NPY and PYY in the teleost-specific tetraploidization. We are now also characterizing receptor families that are closely related to the NPY receptor family, but bind other neuronal and endocrine peptides.

Other projects include growth hormone and prolactin and their receptors as well as some of the most important regulators of growth hormone release, namely the large family of somatostatin receptors. The oxytocin-vasopressin receptor genes also multiplied in the tetraploidizations and, again, mammals have lost one of the ancestral receptors. Both the voltage-gated sodium channels and the calcium channels were duplicated in the tetraploidizations. These gene families are important for neuronal signalling, such as pain transmission.



Daniel Ocampo Daza
David Lagman
Jenny Widmark
Bo Xu
Jasna Pruner
Christina Bergqvist
Ingrid Lundell
Lars G. Lundin