title: Functional characterization of GH-like homolog in amphioxus reveals an ancient origin of GH/GH receptor system.
abstract: Amphioxus belongs to the subphylum cephalochordata, an extant representative of the most basal chordates. Despite many studies on the endocrine system of amphioxus, no evidence showed the presence of pituitary hormones. In this study, we clearly demonstrated the existence of a functional GH-like hormone in amphioxus, which is able to bind purified GH receptors, stimulate IGF-I expression, promote growth rate of fish, and rescue embryonic defects caused by a shortage of GH. We also showed the presence of a GH/prolactin-like-binding protein containing the entire hormone binding domain of GH/prolactin receptors in amphioxus, which is widely expressed among tissues, and interacts with the GH-like hormone. It is clear from these results that the GH/GH receptor-like system is present in amphioxus and, hence, in all classes of chordates. Notably, the GH-like hormone appears to be the only member of the vertebrate pituitary hormones family in amphioxus, suggesting that the hormone is the ancestral peptide that originated first in the molecular evolution of the pituitary hormones family in chordates. These data collectively suggest that a vertebrate-like neuroendocrine axis setting has already emerged in amphioxus, which lays a foundation for subsequent formation of hypothalamic-pituitary system in vertebrates.
authors.affiliation: Laboratory for Evolution and Development, Institute of Evolution and Marine Biodiversity and Department of Marine Biology, Ocean University of China, Qingdao 266003, China.
authors.forename: Mengyang
authors.initials: M
authors.lastname: Li
authors.forename: Zhan
authors.initials: Z
authors.lastname: Gao
authors.forename: Dongrui
authors.initials: D
authors.lastname: Ji
authors.forename: Shicui
authors.initials: S
authors.lastname: Zhang
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D005075:Biological Evolution; D005260:Female; D013006:Growth Hormone / Q000235:genetics* / Q000378:metabolism; D007334:Insulin-Like Growth Factor I / Q000378:metabolism; D064175:Lancelets / Q000235:genetics* / Q000378:metabolism; D008297:Male; D051379:Mice; D008969:Molecular Sequence Data; D051381:Rats; D011986:Receptors, Somatotropin / Q000378:metabolism*; D017386:Sequence Homology, Amino Acid; D014819:Vitellogenins / Q000378:metabolism; D015027:Zebrafish
chemical_list: D011986:Receptors, Somatotropin; D014819:Vitellogenins; D007334:Insulin-Like Growth Factor I; D013006:Growth Hormone