Emergence and evolution of the glycoprotein hormone and neurotrophin gene families in vertebrates

Abstract

Background: The three vertebrate pituitary glycoprotein hormones (GPH) are heterodimers of a common α and a specific β subunit. In human, they are located on different chromosomes but in a similar genomic environment. We took advantage of the availability of genomic and EST data from two cartilaginous fish species as well as from two lamprey species to identify their repertoire of neurotrophin, lin7 and KCNA gene family members which are in the close environment of gphb. Gpha and gphb are absent outside vertebrates but are related to two genes present in both protostomes and deuterostomes that were named gpa2 and gpb5. Genomic organization and functional characteristics of their protein products suggested that gpha and gphb might have been generated concomitantly by a duplication of gpa2 and gpb5 just prior to the radiation of vertebrates. To have a better insight into this process we used new genomic resources and tools to characterize the ancestral environment before the duplication occurred.

Evolutionary history and adaptive significance of the polymorphic Pan I in migratory and stationary populations of Atlantic cod (Gadus morhua)

“…Accordingly, the four genes are positioned on separate chromosomes in tetrapods and Comoran coelacanth, but also in the spotted gar of the holostean fish lineage that diverged from the teleost lineage about 340 Myr ago prior to the 3R genome duplication event (Amores et al, 2011). This agrees with the synteny analyses of vertebrate glycoprotein hormone (GPH) and visual opsin genes revealing a tetraparalogon containing the four physin genes that was explained by the two basal genome duplications (Dos Santos et al, 2011;Lagman et al, 2013). We were not able to not identify the syp gene in the small and stable genome of the holocephalan elephant shark (Venkatesh et al, 2014), while the sea lamprey genome seems to harbor only the syp and sypl genes.…”

Vertebrate Cranial Placodes as Evolutionary Innovations—The Ancestor's Tale

“…Expression of these various hormones in tunicates is concentrated in the CNS (Hamada et al, 2011), and GPA2 and GPB5, which are not well characterized in tunicates, are expressed in the CNS of both arthropods and amphioxus (Dos Santos, Mazan, Venkatesh, Cohen-Tannoudji, & Querat, 2011;Sellami, Agricola, & Veenstra, 2011;Tando & Kubokawa, 2009). This suggests a possible origin of the adenohypophyseal neurosecretory cells from the CNS.…”

Multiple Thyrotropin β-Subunit and Thyrotropin Receptor-Related Genes Arose during Vertebrate Evolution

“…A Tshβ sister gene was however identified in some teleost genomes, that was shown to be derived from the 3R [14], [18].…”